House heating system based on condensing wall boilers. Heat generating devices
INSTALLATION OF THE BOILER
The installation of the boiler and boiler-auxiliary equipment must be carried out by a specialized organization having permission from the Gosgortekhnadzor authorities in accordance with the "Instruction on the procedure for issuing a permit for the right to install boiler supervision objects" approved by the Gosgortekhnadzor.
The installation of the boiler and equipment can be started under the following conditions:
Availability of complete design and estimate documentation, technical documentation of equipment manufacturers and design and installation documentation;
The readiness of the construction part, confirmed by certificates of delivery for installation to the customer of the installation organization;
Completing the facility with equipment, structures, materials, instruments and automation equipment.
Measures to prepare the facility for the start of construction and installation work should be carried out in accordance with VSN217-87 "Preparation and organization of construction and installation work during the construction of boiler houses."
Specific requirements for the arrangement of assembly sites, access roads, sanitary and amenity and storage facilities, connection of electricity, water supply and sewerage, staffing the facility with labor, installation equipment, mechanisms, as well as the technology of work during the installation of equipment are developed in the project for the production of work (PPR), submitted by the installation organization no later than 3 months before the start of work.
Installation of boilers and equipment can be carried out in the following conditions: during the new construction of the boiler house, when expanding the boiler house and during the reconstruction of the facility.
In the conditions of new construction, boilers and equipment are installed, as a rule, either when assembling and construction works are combined, or when construction readiness is high - in
closed building through the left installation openings.
When combining installation and construction works, the installation of boiler blocks on the foundation is carried out using jib cranes in an open building during the construction of structures. United technological sequence installation of boilers, boiler auxiliary equipment and building elements is determined by the project for the production of works.
The installation of the boiler in a closed building is carried out by the sliding method along special rolling paths through the assembly openings provided in the building from the side of the boiler front (axial sliding) or from the end of the building (lateral sliding).
Sliding is carried out using a traction winch fixed at the ends of the tracks behind the boiler foundation.
When installing equipment in a closed building in a limited space, the installation of economizers and draft machines is carried out, as a rule, before the installation of boilers.
The sliding of economizers is carried out using rolling tracks, traction winches and mounting equipment similar to the sliding of boilers.
When expanding the boiler room, installation is carried out as in the case of new construction, in an open building, combined with work on the construction of a boiler room extension or in a closed extension through the mounting openings using a slide.
Boiler house renovation work is often associated with the installation of boilers in an existing building at various construction elevations.
Preparation for installation at the elevation should be carried out in the same way as the preparation of the facility for new construction or expansion of the boiler room, including the implementation of the foundation for the boiler up to the design elevation and the installation of an installation opening. In addition, it is necessary to carry out the departure platform in front of the mounting opening flush with the building mark, and also, if the building is old, check bearing capacity marks, other building structures and, if necessary, strengthen them.
The take-off platform must be equipped with a continuous boardwalk and a fence, the rolling tracks, the outer ends of which are brought out to the take-off platform, must be aligned, secured and lubricated with grease.
Rigging work during the installation of boilers in the conditions of new construction, expansion and reconstruction of boiler houses should be carried out using mechanisms, carrying capacity and tractive effort.
The installation technology, as well as the characteristics of the installation equipment in each specific case, are determined by the project for the production of works.
The main stages of installation of KE boilers are:
Laying out the lining of the slag and ash compartments and installing the power frame (for the KE-25 boiler);
Grille installation;
Installation and alignment of blocks;
Installation of blowers;
Installation of platforms and stairs;
Installation of fittings and pipelines within the boiler;
Hydraulic test;
Boiler lining and casing;
Testing for vapor density.
1. Laying out the lining of slag and ash compartments
and installation of the power frame (for the KE-25 boiler).
The lining of the slag and ash compartments should be laid out according to the drawings of the design organization, taking into account the requirements and recommendations of the furnace manufacturer.
For the KE 25 boiler, first install a load-bearing frame, the columns of which are fastened to the foundation with foundation bolts. Weld the upper support belt to these columns, which is the support frame for the boilers. Permissible deviations of the upper half-belt from the horizontal position no more than + 2 mm.
The distance between the axes of the main longitudinal and transverse beams can deviate from the drawing dimensions by no more than + 3 mm.
After installing the frame, check:
The length and verticality of columns and racks, as well as the horizontalness of the ties with a permissible deviation for the entire length of not more than 5 mm;
The difference in length between the diagonals of the corner columns of the frame, which should not be more than 10mm.
2.Installation of the grille.
The furnaces are mounted according to the drawings developed by the design organization.
Check the equipment for completeness and revise it.
Check the foundation;
Install the combustion drive;
Install the boiler block;
Install front and spreaders;
Install the rear seal;
Mount the air ducts of the grille and projectors;
Run in the grate and spreaders;
Wall up the pre-furnace, the walls of the ash and slag bunkers.
When installing, pay particular attention to the spreaders and the grate drive. Place the grate block on the foundation and align it along the longitudinal axis and the front line of the boiler. The longitudinal axis of the grate must coincide with the axis of the boiler, the distance from the front line of the boiler to the front shaft is 350mm.
Check the diagonals of the grille frame.
The difference in measurements of the diagonals is not more than 10 mm. Check the horizontal position of the grille block in the longitudinal and transverse directions. Permissible deviations from horizontal position no more than 5 mm. Install the support shoes and grout them with concrete. Place the grille drive on the foundation and center it with the front grille shaft, check the alignment of the motor and drive shafts.
Install cast-iron front plates on the air box of the pre-furnace and the boiler frame, on which to hang the spreaders.
Fasten the brackets on the boiler channel in the tail part of the furnaces, in the slots of which to install the shoes. The grates should swing freely in the grooves without jamming.
3. Installation and alignment of blocks.
Before installing the blocks on a foundation or load-bearing frame (for KE-25), it is necessary to perform:
Lining of ash compartments and slag bunkers;
Installation of a power frame (for boilers KE-25);
Installation of a chain grate.
Blocks of boilers KE-4-10 with their front (screen) part are installed on the frame of the TLZM furnace grate, and the rear (convective) part - on the foundation. In the KE-25 boilers, the combustion blocks are installed on the frame of the TCHZM furnace, and the convective one - on the load-bearing frame.
Calibration of the installation of the boiler blocks on the foundation consists in checking the correspondence of the longitudinal axis of the boiler and the front line of the boiler to the mounting axes of the boiler, broken on the foundation; in checking the horizontal position of the upper drum, which is checked using a hydraulic level, the deviation should not be more than 5 mm.
Loosen the bolt connections of the supports on the base frame, which were tightened before transporting the unit, after placing the boiler on the foundation. Install a benchmark (for boilers KE-10 and Ke-25), ensuring the free expansion of the boiler elements according to the installation drawing of benchmarks.When transporting the bulk blocks of the Ke-25 boiler, for greater rigidity, braces from channels are welded along their end walls, which are cut off after installation of the boiler.
4. Installation of blowers.
Before installing the blower, it is inspected.
The blowpipe must be installed horizontally; when installing it, you should pay attention to the fact that the axes are located symmetrically in the gaps between the transverse and longitudinal rows of the convective beam.
After installing the blower, check that there is no binding. The pipe should turn freely and easily.
5. Installation of platforms and stairs.
Installation of platforms and stairs shall be carried out according to the assembly drawing of the manufacturer.
The platforms are installed on brackets welded to the vertical struts of the frame made of channels or corners.
On the platforms and stairs, install a railing with a height of 900 mm, and at the bottom - a continuous sheathing with a height of 100 mm.
The load on the platforms should not exceed 250 kg / m 2.
In the case of using separate sites for assembly and renovation works with a load of more than 250 kg / m 2, local reinforcement of the sites should be carried out.
6. Installation of fittings and pipelines within the boiler.
Under pipelines and fittings within the boiler are meant: elbows for draining water from the lower drum and blowdowns from the screen collectors, connecting elbows for draining water from the lower drum and blowdowns from the screen collectors, connecting pipes for water indicating devices, auxiliary pipeline and blowers, fittings, downpipe and steam outlet pipes (for KE-25).
Before installation, inspect the details of pipelines and fittings. Surface of pipes, shaped
parts, flanges, gaskets, bodies and valve covers should not have cracks, cavities, burrs and other defects that reduce their strength and performance.
Density test locking device produce by working pressure, while tightness standards are adopted in accordance with GOST 9544-75. An act is drawn up on the testing.
The installation of pipelines and fittings within the boiler should be carried out taking into account the following requirements:
Welding of pipelines within the boiler is carried out with electrodes of the ANO-5- (4-6) -1 GOST 9466-75 type or equivalent in mechanical properties weld seam;
When stopping water indicating devices, distortions of fittings and taps are not allowed;
Water-indicating pipes must be installed symmetrically, parallel to the plane of the horizontal axis of the upper drum. The mark of the lowest level is taken 90 mm lower, and the mark top level 90 mm above the horizontal axis from the drum;
Safety valves, in order to avoid skewing and jamming, must be installed strictly horizontally;
Steam lines are installed with a slope from the boiler.
7.Hydraulic test.
Internal inspection and hydraulic test blocks of boilers and other elements were produced in the process of their manufacture at the plant.
After installation and alignment of the boiler blocks on the foundation, welding of water-indicating pipes and bend pipes for draining water to the drums, welding of the bends for blowing to the collectors of screens and installation of fittings, the final hydraulic test of the boiler is carried out in accordance with the "Rules for Boilers" by a special organization licensed by Gosgortekhnadzor ...
The hydraulic test must be carried out at an ambient temperature below + 5 0 C. The water temperature for filling the boiler must not be lower than +5 and not higher than +40 0 C. The pressure of the hydraulic test and settings safety valves are given in table. 3, as well as in the boiler passport.
Under the operating pressure in the boiler rises overpressure steam and water at the outlet of the boiler drum.
The pressure rise time during hydrotesting must be at least 10 minutes, the holding time under test pressure must also be at least 10 minutes. The rise and fall of pressure is done gradually. control the water pressure during testing with two pressure gauges, one of which must have an accuracy class of at least 1.5. The safety valves are seized and the water indicator valves are seized and the water indicator glasses overlap.
After holding under test pressure, reduce its working pressure and inspect the rolling and welded joints. since boilers have small areas of welded seams and rolling joints that are difficult to inspect during a hydraulic test, it is recommended, after reducing the pressure to working pressure, to maintain it for the time required for inspection.
During the hydraulic test, there should be no leakage, tears and sweating in the base metal in welded joints. The tightness of the rolling joints can be compromised as a result of non-observance of the conditions for loading and unloading blocks, transportation by rail (other modes of transport) and at the assembly site. If any leaks in the rolling joints are found, drain the water from the boiler and eliminate the leaks.
Re-flaring is allowed no more than three times. If it is impossible to eliminate leaks by additional flaring of pipes, flaring joints should be replaced with welded ones in accordance with the guidelines for welding RTM-I S-89.
After elimination of violations, the boiler must be presented to the Gosgortekhnadzor authorities for technical examination.
8. Lining and insulation of boilers.
The lining and insulation of boilers should be carried out according to the drawings of the plant and the documentation of the boiler room project.
Tight shielding of the side walls allows the use of insulation of 100-105 mm, laid on a layer of chamotte concrete applied over a grid. It is attached to the pipes of the side screens and stretched braided mesh, which is upset to the pipes. In places with a sparse pipe pitch, a layer of plywood, roofing roofing or cardboard that is supported before concreting with shomoto concrete is laid. Then apply fire concrete, which is evenly distributed over the mesh and carefully compacted. The thickness of the chamotte concrete should be 25 mm from the outer generatrix of the pipe.
3-4 hours after laying the fire-resistant concrete, it should be moistened by sprinkling with water and rubbing the cracks that appear. Curing of chamotte concrete should take place at an ambient temperature of at least +5 0 С, At an ambient temperature above +10 0 С, chamotte concrete should be covered with plastic wrap or other material to avoid rapid evaporation of water and moisten it with water every 3-4 hours.
After the fire-resistant concrete has hardened (if the concrete is prepared on alumina cement, then in a day) install heat-insulating plates. Before that, check the state of the fire-resistant concrete and eliminate all defects and imperfections, since poor-quality performance of the heat-resistant layer (cracks, leaks) can lead to a local increase in the wall temperature. Thermal insulation boards install close to the layer of fire-resistant concrete.
When laying slabs, it is necessary to strictly monitor the implementation required thickness the seam and its full filling with mortar.
the first layer of lining of the front and rear walls is laid with fireclay bricks, the second layer of the front of the furnace is mullite-silica felt.
The outer lining layer is a gas-tight lining. The coating layer is about 5 mm. The coating should not have cracks and leaks, which, during the start-up and operation of the boiler, would lead to shine through and leakage of flue gases between the insulation and the casing in the direction of places where the vacuum in the gas duct increases. During the installation process, it is necessary to provide natural ventilation sufficient for drying the lining, which will avoid corrosion of pipes from the side of the position of the chamotte concrete.
When performing lining work, the following requirements must be observed:
The seams in the masonry should be spaced apart; the coincidence of the vertical seams of two adjacent rows is not allowed;
Before laying on the mortar, adjust each row of bricks and make up dry;
Chipping the brick by hand with frequent, but not strong blows.
When performing the brickwork, special attention should be paid to its density in the places where the headset is installed.
After the completion of the insulation work, the boiler casing is installed according to the manufacturer's drawings. Welding the casing to the frame provides the necessary density of the boiler walls to exclude excess cold air suction. Remove slag and burr from welded seams. Check the tightness of the casing with a torch, creating a vacuum in the furnace of about 100 mm Hg. Oscillation of the torch will indicate the place of lack of penetration. You can also check the tightness of the casing by creating a pressure in the furnace of about 100 mmHg. and smearing the welds with soapy water. In places of lack of penetration, soap bubbles will be blown out.
In case of long-term storage of the boiler after the installation of the lining and casing before the boiler is put into operation, in order to avoid oxygen corrosion of the pipe metal from the lining side, it is recommended to dry the lining for 2-3 days with electric heaters, on wood or using steam from working boilers, which is supplied to the filled with water to the lower level boiler through the heating line of the lower drum. The process of heating the water in the boiler must be carried out gradually and continuously, while monitoring the water level in the water indicating glasses. By the end of drying, the temperature of the water in the boiler is maintained at 80-90 0 C. When the boiler block is supplied in lining and cladding, the installation is made to insulate the upper and lower drums and the rear bottom with 60-80 mm thick covelite plates, asbestos-ovalite mastic, metal mesh and cloth cotton in accordance with GOST 3357-72.
The partition between the firebox and the convective tube bundle is made according to the manufacturer's drawings.
9. Alkalization and boiler vapor density test.
After completion of installation and drying of the lining, alkaline is required to clean the internal surfaces of the boiler from oily deposits.
It is advisable to use chemically purified water to fill the boiler during alkalization and make-up during the alkalization period. It is allowed to fill the boiler with raw clarified water with a temperature not lower than + 5 0 С.
The superheater is not subject to alkalization and is not filled with an alkaline solution. It is cleaned of oily contaminants and rust with a steam flow, for which the purge valve of the superheater is opened before alkalization.
Before alkalizing the boiler, the boiler is being prepared for firing up.
In order to save time and fuel, the introduction of reagents and the beginning of alkalization of the boiler should be carried out one day before the end of the drying of the brickwork.
The introduction of reagents can be carried out by means of a dispenser pump with a capacity or through a tank with a capacity of 0.3-0.5 m 3, installed above the platform of the upper drum.
From the tank, a solution of reagents flexible hose enter through the valve of the branch pipe "for own needs".
For alkalization, reagents are used: caustic (caustic soda) or soda ash and trisodium phosphate, the consumption of which is given in table. 4
Note:
1. Weights are for 100% reagent.
2. The lower value of the reagent is for boilers with a slight rust (in some places), the larger value is for boilers with a large layer of rust (solid).
Reagents dissolve before injection to a concentration of about 20%. solutions of soda and trisodium phosphate must be introduced separately in order to avoid crystallization of trisodium phosphate in the boiler pipes. It is possible to introduce a solution of reagents from the tank into the boiler only in the complete absence of pressure in the latter. The personnel working on the operations for preparing the solution and putting it into the boiler must be provided with special clothing (rubber aprons, boots, rubber gloves and masks with goggles).
Before the boiler is fired up for the first time after installation, the springs of the safety valves are loosened if the valves have not been adjusted on the bench. Each time the pressure rises with alkalisation (0.3; 1.0; 1.3 MPa), by tightening the nuts, the spring pressure on the steam pressure valve is matched.
If alkaline, after adding reagents, fire up the boiler in accordance with the requirements of section 7, raise the pressure in the boiler to 0.3-0.4 MPa _3-4 kgf / cm 2), tighten the bolted connections of hatches and flanges. Alkaline at this pressure for 8 hours with the boiler load no more than 25% of the nominal.
Blow out the boiler at all points for 20-30 seconds. each and feed to the top level.
Reduce pressure to atmospheric.
Raise the pressure to 1.0 MPa (10kgf / cm 2) and alkali at a load of no more than 25% -6 hours.
Blowing and feeding the boiler with a pressure drop to 0.3-0.4 MPa _3-4 kgf / cm 2).
A new rise in pressure up to 1.3 MPa (13 kgf / cm 2), and for boilers for an overpressure of 2.3 MPa
(23 kgf / cm 2) and alkalization at a load of no more than 25% for 6 hours.
Change of boiler water by means of multiple blowdowns and filling of the boiler.
During alkalization process, do not allow water to flow into the superheater. The superheater purge valve is open at all times. The total alkalinity of the boiler water during alkalization must be at least 50 mg.eq / l. With a decrease below this limit, an additional part of the reagent solution is introduced into the boiler, while the pressure in the boiler should not exceed atmospheric.
the end of alkalization is determined by performing analyzes for the stability of the P 2 O 5 content in water.
After alkalization, the pressure is reduced to zero after the water temperature has dropped to 70-80 0 С, water is drained from the boiler.
The hatches of the drums and the hatches of the collector are opened, the drums are thoroughly washed, inside the drum devices, pipes from a hose with a union with a pressure of 0.4-0.5 MPa (4-5 kgf / cm 2), preferably with a temperature of 50-60 0 C.
The state of the heating surfaces is recorded in the HVO log. After alkalization, it is necessary to revise the purge and drain fittings and water-indicating glasses.
If the period between alkalization and boiler start-up exceeds 10 days, then it must be put on storage.
Testing for steam density is carried out at the end of alkalization and revision of the boiler.
After the pressure in the boiler rises to 1 MPa (10kgf / cm 2), a second pressure gauge is connected to the three-way valve of the boiler pressure gauge and the readings of the working pressure gauge are checked against it.
In the event of a discrepancy in the readings by an amount exceeding the error of the working manometer, the latter must be replaced.
10. Adjustment of safety valves.
Adjustment of safety valves can be carried out on the bench, during hydraulic tests or in the alkalization process when steam is discharged through the auxiliary line and mounted steam pipelines.
The safety valves should be revised prior to installation. Lubricate the thread of the pressure sleeve (20% silver graphite, 70% glycerin, 10% copper powder) check the condition of the sealing surfaces, the presence of stem seals.
The pressure rises slowly and the safety valves are adjusted to the pressure of the beginning of opening, indicated in table. 3.
The safety valves are adjusted one by one in the following sequence:
Set the required pressure in the boiler;
Remove the manual trigger and the protective cap;
By unscrewing the pressure nut, achieve the beginning of the valve detonation;
Reduce the pressure in the boiler before the valve is seated, while the difference between the blasting pressure and the seating pressure of the valve must be at least 0.3 MPa. By turning the damper sleeve clockwise, the difference increases, while against it, it decreases. To rotate the damper sleeve, it is necessary to loosen the screw, at the end of the adjustment, stop the specified visit;
Measure the height of the spring tightening, with an accuracy of 1mm and write it down in the removable journal;
At the end of the adjustment, replace the protective cap and the manual trigger;
Seal the protective cap of the valve.
The absence of steam and water passes through the joints of the individual elements of the boiler and fittings, the trouble-free operation of the safety valves are an indicator of sufficient steam density.
A certificate is drawn up for testing the boiler for steam density with the adjustment of the safety valves and an indication of the response pressure.
After testing for steam density, warm up and purge the steam line from the boiler to the points of connection to the working sections of the steam lines or to consumers.
During warming up and purging, the following operations are performed:
The pressure in the boiler rises to the working one;
The level rises above the average by 30mm; - the air vent and drain valves on the steam line open;
Gradually open the steam shut-off valve, reaching the highest steam consumption within 5-10 minutes, while it is necessary to monitor the water level in the boiler.
Note: The procedure for purging the steam line may be different. It is governed by the requirements production instructions depending on the schemes of steam pipelines, blowdown pipelines and automation of valve control.
11. Integrated testing of boiler units and adjustment during integrated testing.
Comprehensive testing is carried out after testing the boilers for steam density and is the final stage of installation work.
The general and subcontractor that installs the boiler, instrumentation, auxiliary equipment, electrical and other work, during the comprehensive testing of the boiler unit, ensure the watch of their personnel to promptly eliminate the identified defects in construction and installation work in accordance with the requirements of SNiP 3.01.04-87.
Before performing complex testing, the customer, together with the commissioning organization, draws up a testing program. Comprehensive testing is carried out by the customer's personnel with the involvement of specialist adjusters.
Loads for complex testing are determined in the program (as a rule: nominal, minimum possible, intermediate).
Testing of the boiler in combination with an economizer, draft mechanisms, a pipeline system, auxiliary equipment of a boiler room, an instrumentation and control system is carried out within 72 hours. During this period, the commissioning organization performs the adjustment of the furnace and water-chemical regime of the system, instrumentation and automation with the issuance of temporary regime cards.
After the end of the comprehensive testing, defects and malfunctions identified in the course of its implementation are eliminated (if necessary, the boiler stops), an act of comprehensive testing and commissioning of the boiler is drawn up.
12. Acceptance after installation.
In the process of preparation, installation and commissioning of the boiler in accordance with the requirements of SNiP 3.01.04-87 and other documents, the following production documentation is subject to registration and transfer of the boiler to the working commission:
Boiler health certificate;
Equipment transfer certificate for installation;
The act of readiness of the foundation for the production of installation work;
The act of checking the installation of equipment on the foundation;
Certificate of completion of installation and inspection of the internal drum device;
Boiler hydraulic test certificate;
Boiler lining acceptance certificate;
Test report for the density of the gas-air path with the boiler furnace;
Boiler installation quality certificate;
Boiler alkalization certificate.
"Housing and communal services: accounting and taxation", 2009, N 4
It is no secret that there are boiler houses on the balance sheets of many housing and communal services enterprises, which, probably, have already faced the issues of accounting and taxation of this property. The difficulty is that the boiler room includes not only the building as a real estate object, but also the equipment placed in it. The reader will learn how to combine these two components in accounting and taxation, in particular, when calculating property tax, from the presented article.
A few words about the state registration of the boiler house and equipment
The building in which the equipment is located is one of those objects, the movement of which is impossible without causing disproportionate damage to its purpose, that is, real estate, the rights to which are subject state registration(Article 1 of Law N 122-FZ<1>). This statement is true in relation to capital buildings and buildings, that is, to stationary boiler houses, which are mainly operated by housing and communal services enterprises. Block-modular and transportable boiler houses, indispensable in case of emergency outages of heat supply, are not real estate from the position of Law N 122-FZ. The same can be said about boiler room equipment, which is mounted indoors and does not include heating network... Installation and dismantling of boiler equipment by specialists is possible without damage to this property, so it does not need a separate state registration. At the same time, there are other equipment for the equipment. mandatory requirements which we will focus on below.
<1>Federal Law of 21.07.1997 N 122-FZ "On state registration of rights to real estate and transactions with it".
Accounting for the boiler house building
Since the procedure for accepting a real estate object for accounting depends on whether it is acquired under a sale and purchase agreement or is being erected by the organization independently (with the involvement of contractors), we will consider these situations sequentially.
Acquisition of the boiler house building
When purchasing a boiler house under a sale and purchase agreement, the buyer reflects in the accounting the costs of its acquisition as part of investments in non-current assets (account 08). The next operation to transfer property to fixed assets (Debit 01 Credit 08) causes taxpayers and inspectors to disagree with the state registration of real estate. The reason is that the financial department in its early clarifications indicated that the fact of state registration of rights to real estate is the basis for its transfer by the buyer to the OS<2>, and some courts adhered to the same position (Resolution of the FAS UO of 21.01.2008 N F09-11263 / 07-C3). At the same time, the officials believed that the taxpayer should not evade state registration. If the new owner is in no hurry to register, which is not at all in his interests, then this circumstance does not give the right not to pay property tax (Definition of the Supreme Arbitration Court of the Russian Federation of February 14, 2008 N 758/08).
<2>Letter of the Ministry of Finance of Russia dated 06.09.2006 N 03-06-01-02 / 35 brought up by Letter of the Federal Tax Service of Russia dated 10.11.2006 N MM-6-21 / [email protected], while the legality of the explanation was confirmed by the Decision of the Supreme Arbitration Court of the Russian Federation of October 17, 2007 N 8464/07.
The organization may not shy away, but at the same time significantly delay the registration of ownership and registration of the real estate object, which, of course, is beneficial from the point of view of calculating property tax. In the latest clarifications, officials expressed a slightly different opinion. So, for example, in the Letter dated 03.03.2009 N 03-05-05-01 / 15, the Ministry of Finance admits the reflection of real estate objects as part of fixed assets, if capital investments are completed on them, a "primary" for acceptance and transfer has been drawn up, the relevant documents have been submitted for state registration , and the object itself is actually being operated. The financial department does not set out a clear position, therefore, let us turn to arbitration practice, in which the starting point is the obligation to calculate property tax, depending on the accounting of objects.
The courts note that neither PBU 6/01 "Accounting for fixed assets", nor the Guidelines for accounting for fixed assets<3>do not contain both requirements for state registration of rights, and the concept of "commissioning" of fixed assets. Moreover, earlier in clause 4 of PBU 6/01, among the conditions for accepting an object for accounting in the fixed assets, the actual use in entrepreneurial activity, and now it is only the intended purpose for such activities. You must agree that the issue of including property in the composition of taxable objects cannot depend on the will of the taxpayer, but should be determined by the economic essence of this property, as indicated by the arbitrators.
<3> Methodical instructions on accounting of fixed assets, approved. By order of the Ministry of Finance of Russia dated October 13, 2003 N 91n.
In the Resolution of the FAS VVO dated 12.05.2008 N А43-21471 / 2007-6-749 it is said that the organization is obliged to include in the calculation of property tax the cost of the boiler houses transferred to it from the moment of signing the acts of acceptance and transfer of this property, and not from the date of state registration transfer of ownership of these objects. Already from the moment of transfer, they possessed all the features of the OS established in clause 4 of PBU 6/01, including those used by the company in its economic activities. Therefore, the organization has no reason to delay the transfer of the accepted and operated property from the investment account in non-current assets to the account of fixed assets taxed with property tax. The Collegium of the Supreme Arbitration Court of the Russian Federation agreed with the position of the arbitration court - by its Resolution No. 11258/08 of 19.09.2008, it refused to transfer the case to the Presidium of the Supreme Arbitration Court for review by way of supervision.
In the Resolution of the FAS SKO dated 08.10.2007 N F08-6588 / 2007-2440A, the issue of accounting and taxation of the boiler house, which the organization, together with other real estate, received on the basis of a compensation agreement, was also considered. The company recorded the specified property on account 08, and on account 01 this property was delivered on the day of state registration of ownership. In the opinion of the arbitrators, the legislation does not establish such a condition for the reflection of property in the accounting as a fixed asset, such as the presence of state registration of ownership of the property put into operation and actually used. The obligation to take into account the value of the property when calculating the tax arises from the moment of signing the acceptance certificate and the actual receipt of the property, and not at the time of submission of documents for state registration. As in the previous case, the taxpayer failed to get the case reconsidered (Definition of the Supreme Arbitration Court of the Russian Federation of 28.04.2008 N 16599/07). And this confirms the postulate that the fact of registration of the right to real estate is not decisive in the accounting of property as part of fixed assets. The obligation to calculate property tax arises from the moment the object is used in entrepreneurial activity. Registration of the act of acceptance and transfer later than the actual transfer of property cannot be the basis for exemption from taxation (Resolution of the FAS VVO dated December 31, 2008 N A82-13787 / 2007-27).
So, if we rely on court decisions, then the adopted and actually operated boiler house is registered as an asset until the completion of state registration<4>... Suppose that an organization is denied registration (for reasons that are independent or beyond its control). What, then, are the actions of the organization and the accountant? According to paragraph 5 of Art. 2 of Law N 122-FZ, the refusal of state registration of rights or the evasion of the relevant authority (Rosregistratsiya) from state registration can be appealed by the interested person in court. By the Decree of the President of the Russian Federation of December 25, 2008 N 1847, the Federal Registration Service was renamed into Federal Service state registration, cadastre and cartography with the assignment to it of the functions of organizing a unified system of state cadastral registration of real estate and state registration of rights to real estate and transactions with it.
<4>If, before registration, the buyer does not use the property and it is idle with the seller, then it should be reflected as part of fixed assets from the date of state registration and commissioning with the buyer.
If the organization disputes the decision of this body, the accountant, while the trial is underway, does not need to change the accounting procedure for the boiler house reflected in the OS. Indeed, in the process of registration, refusal and appeal of the decision of the registering authority, the boiler room adopted under the acceptance certificate continues to be at the disposal of the organization and is used in its activities, that is, it brings economic benefits (income). In this regard, while the court is underway, the accountant should not rush to write off the boiler house accepted on the balance sheet, in addition, all operations must be drawn up with primary documents, and in this case, the refusal of the authority to register (if the organization decided to appeal against it) is not a final document, on the basis of which the object changed its owner. Until the end of the proceedings, the buyer actually remains in this role, using the property transferred to him as an asset and lawfully calculating depreciation on it (and paying property tax).
Let's admit the worst case - the concluded purchase and sale agreement was declared invalid by the court. This means that each of the parties to the transaction is obliged to return to the other party everything received under the transaction (clause 2 of article 167 of the Civil Code of the Russian Federation). An organization that failed to register ownership returns the property to the seller, who, in turn, is obliged to return the money received. In accounting, the retired property is written off from the accounting (clause 29 of PBU 6/01), while the amounts of uncalculated depreciation (residual value) are included in other expenses (Debit 91-2 Credit 01). Other income includes the funds returned by the seller (Debit 51 Credit 91-1). In principle, it would be possible, instead of other expenses and income, to use a settlement account (Debit 76 Credit 01, Debit 51 Credit 76). The problem is that part of the cost of fixed assets for the period from the moment of acceptance and transfer to the recognition of the contract as invalid was depreciated, therefore, the account of calculations in the assessment of fixed assets in the accounting and the contract may not converge. The accounting methodology prescribed in the Instructions for the Application of the Chart of Accounts speaks in favor of the first option (the use of an account for accounting for other income and expenses). Note that if, before registration, the boiler house building would have been accounted for as part of investments in non-current assets, then in case of refusal to register and invalidate the contract, the accountant could write off the non-current asset that was not depreciated to the account of settlements, and its accounting estimate could coincide with the estimate , according to which settlements were made with the seller.
And one more thing: in practice, under a sale and purchase agreement, an organization can acquire an unfinished property, which is supposed to be used as a boiler house in the future. Such objects of unfinished capital construction are accounted for as part of capital investments and, prior to their transfer to the fixed assets, cannot be considered as an object of property taxation (Resolution of the Federal Antimonopoly Service of Moscow from 24.12.2008 N КА-А41 / 12033-08). But sooner or later the facility will be completed. At what point after that will it become a primary taxable vehicle?
Construction of the boiler house building
During the construction of the boiler house on its own, the organization will have to go all the way: from design work, equipment and ending with the installation and commissioning of the boiler house. As a result of these works, an investment object is created, and therefore the costs of their implementation cannot be attributed to current costs, but must be taken into account as part of capital investments (Resolution of the FAS SZO dated June 29, 2007 N A56-10135 / 2006). All preparatory and construction work will form the actual value of the object by accumulating as part of investments in non-current assets. In the same order, objects that are in temporary operation are reflected until they are put into permanent operation (clause 41 of the Regulation on accounting, approved by Order of the Ministry of Finance of Russia dated July 29, 1998 N 34n).
To take the constructed object into account as an OS, the organization needs to put it into operation. And this is possible only if there is an appropriate permit for the commissioning of the facility during construction. It is the permission that is the basis for the state registration of the constructed capital construction object (Article 55 of the Civil Code of the Russian Federation). Issuance of permits is within the competence of local self-government bodies of municipal districts and urban districts in the field of urban planning (subparagraph 5 of paragraph 1 of article 8 of the Civil Code of the Russian Federation, paragraph 26 of article 16 of the Law on the principles of organizing local self-government<5>).
<5>Federal Law of 06.10.2003 N 131-FZ.
They were previously vested with the same powers in terms of issuing certificates of acceptance into operation of the completed construction of the facility, which are named in SNiP 3.01.04-87<6>... The acts were signed and approved by the decision of the bodies that appointed the acceptance commission, while the object was considered adopted only after the act was approved by the authorized body (clauses 4.27, 4.28 of SNiP 3.01.04-87). During the period of validity of these provisions (before the introduction of the Town Planning Code), the obligation to register a completed construction object (boiler house) as a fixed asset and, accordingly, to pay property tax arose from the moment the acts were approved by the local government, and not from the moment of signing, as was believed sometimes tax authorities (see Resolution of the FAS VVO dated 12.05.2008 N А43-21471 / 2007-6-749). Today, instead of the act of the state acceptance commission, the organization needs to obtain permission to put the facility into operation, which, according to the author, does not change the main thing - the procedure for registering the facility and calculating tax. This can be done from the moment of obtaining permission for commissioning, without waiting for the ownership of the organization that invested in the construction of the real estate object to be registered.
<6>SNiP 3.01.04-87 "Acceptance for operation of completed construction facilities. Basic provisions", approved. Resolution of the USSR State Construction Committee of 04/21/1987 N 84.
To include the constructed boiler house in the OS, all work at the facility must be completed and all the necessary life support systems must be connected. Until the tax authority submits evidence of the completion of the construction of such an object (the end of capital investments, the execution of documents for the acceptance and transfer of the object, its proper commissioning, etc.), its claims regarding the accounting of the object as part of the OS and the calculation of property tax are unfounded (Resolution FAS UO dated 11.10.2007 N F09-8293 / 07-C3). It must be admitted that the construction of a boiler house is sometimes more expensive than the reconstruction of an existing one, therefore, sometimes organizations acquire a used boiler house and, if necessary, carry out its additional equipment and re-equipment.
Reconstruction of the boiler house building
The need for reconstruction may arise both in relation to an operating boiler house, and in relation to an idle facility acquired under a sale and purchase agreement. In the first case, with a partial reconstruction of an object accounted for as part of a fixed asset (without a complete stop or complete cessation of its use), the depreciation charge on it is not suspended (in the same way, the payment of property tax continues). In addition, PBU 6/01 does not provide for the allocation of a part of the object to be reconstructed into a separate inventory object. The corresponding recommendations are contained in the Letter of the Ministry of Finance of Russia dated January 29, 2009 N 07-02-18 / 01. If the boiler house undergoes significant reconstruction (for example, in the conversion from one energy source to another), then the accountant can also continue to accrue depreciation, provided that the restoration period of the object does not exceed a year (clause 23 PBU 6/01).
This approach greatly simplifies the work of an accountant, since depreciation is charged in the same order until the reconstruction is completed. After that, you will have to increase the cost of the OS and, possibly, the term useful use, if performance characteristics boiler room have improved.
If a boiler house is purchased under a sale and purchase agreement, after which it is immediately reconstructed, then before its completion the organization has no reason to include the boiler room in the fixed assets (even if the sale and purchase agreement has passed state registration). The decisive factor for the accounting of fixed assets is bringing the object into a condition suitable for operation, which occurs after the reconstruction of the boiler house.
Boiler room equipment
The main issue of accounting for boiler room equipment is whether it needs to be reflected in the cost of the entire boiler room complex as an OS object or can it be separated into a separate inventory object. There are two opinions on this score.
On the one hand, the boiler room equipment is an integral part of the real estate object itself, since it cannot separately perform its functions in isolation from the premises. This is supported by the All-Russian Classifier of Fixed Assets OK 013-94<7>, in which, in particular, it is said that buildings include communications inside buildings necessary for their operation, including a heating system, including a boiler installation for heating (if the latter is located in the building itself). Thus, on the balance sheet, the property of the boiler house (real estate object, utilities, technological equipment, inventory and measuring instruments) can be accounted for as part of a single complex.
<7>Approved by the Resolution of the Gosstandart of Russia dated December 26, 1994 N 359.
In favor of the accounting and use of the building and equipment of the boiler house as part of a single object, it is possible to cite the Resolution of the FAS SZO dated January 14, 2008 N A56-22455 / 2006. Heating equipment was located in the building, which was under the operational management of the state institution. It had the necessary license and equipment to provide heat to its buildings. The technological equipment was sold to another organization, but the building itself remained in the operational management of the institution, which had reason to restrict the new owner of the equipment to the disposal of this property.
Note that it is beneficial to take into account the equipment together with the building as part of a single inventory object of the boiler house. In this case, work on the replacement of equipment (unless they are modernization) will be considered a repair and the corresponding expenses can be written off to the financial result of the reporting period. In contrast to this, in the Decree of the FAS SZO dated September 28, 2004 N A56-16861 / 04, the tax authorities qualified the pump, gas contamination unit, pumping unit, electric motor and grounding device purchased for repairing the boiler room as independent objects of the OS. In the case under consideration, the organization did not accept the components for accounting as a fixed asset, but reflected their value on account 26 "General expenses", since they were acquired for the purpose of repairing individual units of the boiler room and could only function as part of the boiler room complex. On this basis, the taxpayer considered that the useful life of each component cannot be different than the useful life of the boiler house as a whole. The court agreed with these arguments, and the tax authorities' claims regarding the capitalization of the costs of repairing the boiler house were found unfounded.
On the other hand, it is possible to account for the building and boiler room equipment separately if they have significantly different useful lives. This procedure is allowed by clause 6 of PBU 6/01. The level of materiality in the named PBU is not fixed, therefore it should be determined independently in the accounting policy. If the useful life of the equipment differs from the period of use of the boiler house above this level, then the organization has the right to record such property as a separate inventory item. The legality of this approach is confirmed by court decisions. As follows from the Resolution of the FAS ZSO of 20.01.2009 N F04-8218 / 2008 (19023-A46-26), the organization was in no hurry to put the equipment into operation, believing that this should be done only after the mounted objects were put into operation. as part of a single functioning complex of structurally articulated objects (processing line). Such actions were recognized by the tax authorities and the court as unlawful due to the fact that the disputed equipment as an independent object possessed all the signs of OS. This does not take into account the fact that the production process was not adjusted by the organization. Recall that for fixed assets, the purpose is necessary, and not use in the production of products (performance of work, provision of services).
The accounting of equipment and the building of the boiler room as separate inventory objects also has its advantages. For example, when replacing equipment with a newer and more perfect one, the accountant should reflect the replacement of the fixed asset (disposal and receipt), and not modernization, as if the equipment would be taken into account as part of the entire boiler house complex. To this we add that the cost of equipment as a separate object of fixed assets can be written off sooner than if it would be depreciated as part of the entire boiler house.
So, we have given two options for reflecting the boiler room equipment in the accounting, the reader, taking into account specific circumstances, needs to choose one of them. In addition, you should know a number of requirements for boiler equipment.
Basic requirements for boiler equipment Boiler room as a hazardous facility
Hazardous production facilities are subject to registration in the state register in accordance with the procedure established by the Government of the Russian Federation (clause 2 of article 2 of the Federal Law of 21.07.1997 N 116-FZ "On industrial safety hazardous production facilities "). At the moment, the Administrative Regulations on the registration of hazardous production facilities are in force.<8>... It applies to facilities that include an enterprise or its workshop, site, site, as well as other facilities where:
- obtained, used, processed, formed, stored, transported, destroyed hazardous (flammable, oxidizing, combustible, explosive, toxic, highly toxic) substances;
- equipment is used that operates under a pressure of more than 0.07 MPa or at a water heating temperature of more than 115 degrees Celsius.
Under the last sign dangerous object a boiler house (a group of boiler houses), working for the heating network of the city and other settlement, falls. The boundaries of a hazardous production facility are the boundaries of the territory served by the heat and power organization of housing and communal services. The presence of gas in internal systems gas supply to the boiler room is identified separately based on the presence of flammable substances in a hazardous production facility, which is a heat supply system serviced by a housing and communal services organization<9>... Thus, technological equipment can define a boiler room as a hazardous production facility based on two criteria at once: hazards for boilers and hazards for gas equipment... With regard to hazardous facilities, the regulation provides for:
- registration of an object with assignment of a number in the register of hazardous production facilities;
- issuance by the registering authority of an approved hazardous facility registration card and a certificate of registration of a hazardous facility to the operating organization.
After the boiler house is registered in the register of hazardous objects, its operation is periodically checked by the supervisory authorities. Inspectors can come with a check to any enterprises that have controlled facilities: electrical installations, heat installations, hazardous production facilities, etc.
License
The operation of explosive and fire hazardous facilities is subject to compulsory licensing by virtue of paragraphs. 28 p. 1 of Art. 17 of the Federal Law of 08.08.2001 N 128-FZ "On Licensing Certain Types of Activities". The corresponding Regulation on licensing, containing the procedure for obtaining a license and licensing requirements, was approved by Decree of the Government of the Russian Federation of August 12, 2008 N 599. The licensing body is Rostekhnadzor.
Gas supply permit
It is no secret that many boiler houses use blue fuel as an energy resource. In this case, the norms of the Rules for the supply of gas to the Russian Federation should be taken into account.<10>mandatory for all legal entities involved in the supply of gas through pipeline networks. Gas supply organizations are charged for connecting objects to gas networks. To use gas as a fuel, its buyer must have a gas supply permit (clause 4 of the Rules for Gas Supply to the Russian Federation).
<10>Approved by the Decree of the Government of the Russian Federation of 05.02.1998 N 162.
The obligation to obtain the said permit is due to the legal entity's status as a gas buyer and is not related to the rights to gas-consuming equipment (it is owned or leased). The fact that the enterprise operating the boiler house does not have an appropriate permit to use gas as fuel deprives it of the opportunity to exercise the right to conclude a gas supply agreement with a gas supplying organization. Even if an enterprise has a pre-emptive right to conclude a gas supply agreement in view of the generation of heat for the housing stock, this does not exempt it from obtaining a permit. The lack of permission is regarded as the inability to provide services, which, by virtue of paragraph 3 of Art. 426 of the Civil Code of the Russian Federation exempts the energy supplying organization from the obligation to conclude an agreement with the boiler house (Resolution of the FAS SZO dated 17.10.2005 N A13-737 / 2005-13).
Certification
Boiler plants with stationary installed boilers, stationary hot water boilers, direct-flow boilers, steam and heating boilers are subject to mandatory certification. A more detailed list of devices and equipment of the boiler house subject to certification can be found in the Nomenclature of products for which mandatory certification is provided by the legislative acts of the Russian Federation (enacted by the Resolution of the Gosstandart of Russia dated July 30, 2002 N 64).
S.N.Zinoviev
Journal Expert
"Housing and utilities:
accounting and taxation "
A boiler plant (boiler room) is a structure in which the working fluid (heat carrier) (usually water) is heated for the heating or steam supply system, located in the same technical room. Boiler rooms are connected to consumers using heating mains and / or steam pipelines. The main device of the boiler room is a steam, fire tube and / or hot water boilers. Boiler houses are used for centralized heat and steam supply or for local heat supply of buildings.
A boiler plant is a complex of devices located in special rooms and serving to convert the chemical energy of fuel into thermal energy of steam or hot water... Its main elements are a boiler, a combustion device (firebox), feed and draft devices. In general, a boiler plant is a combination of a boiler (s) and equipment, including the following devices: fuel supply and combustion; cleaning, chemical preparation and deaeration of water; heat exchangers for various purposes; pumps of initial (raw) water, network or circulation - for circulation of water in the heat supply system, make-up - to replace water consumed by the consumer and leaks in networks, feed pumps for supplying water to steam boilers, recirculation (mixing); feed tanks, condensation tanks, hot water storage tanks; blowing fans and air duct; smoke exhausters, gas path and chimney; ventilation devices; systems for automatic regulation and safety of fuel combustion; heat shield or control panel.
A boiler is a heat exchanger in which the heat from the hot combustion products of the fuel is transferred to the water. As a result, in steam boilers, water is converted into steam, and in hot water boilers it is heated to the required temperature.
The combustion device is used to burn fuel and convert its chemical energy into heat of heated gases.
Feeding devices (pumps, injectors) are designed to supply water to the boiler.
The draft device consists of blowing fans, a system of gas ducts, smoke exhausters and a chimney, with the help of which the supply the required amount air into the furnace and the movement of combustion products through the boiler gas ducts, as well as their removal into the atmosphere. Combustion products, moving along the gas ducts and in contact with the heating surface, transfer heat to the water.
To ensure more economical operation, modern boiler plants have auxiliary elements: a water economizer and an air heater, which respectively serve to heat water and air; devices for fuel supply and ash removal, for cleaning flue gases and feed water; thermal control devices and automation equipment that ensure the normal and uninterrupted operation of all parts of the boiler room.
Depending on the use of their heat, boiler houses are divided into power, heating and production and heating.
Power boiler houses supply steam to steam power plants that generate electricity and are usually part of a power plant complex. Heating and industrial boilers are located at industrial enterprises and provide heat to the heating and ventilation systems, hot water supply of buildings and technological production processes. Heating boiler houses solve the same problems, but serve residential and public buildings... They are divided into free-standing, interlocked, i.e. adjacent to other buildings, and embedded in buildings. V recent times more and more freestanding enlarged boiler houses are being built with the expectation of servicing a group of buildings, a residential quarter, a microdistrict.
The installation of boiler houses built into residential and public buildings is currently allowed only with appropriate justification and agreement with the sanitary supervision authorities.
Low-power boiler houses (individual and small group) usually consist of boilers, circulation and feed pumps and draft devices. Depending on this equipment, the dimensions of the boiler room are mainly determined.
2. Classification of boiler plants
Boiler plants, depending on the nature of consumers, are divided into power, production and heating and heating. According to the type of heat carrier obtained, they are divided into steam (for generating steam) and hot water (for generating hot water).
Power boiler plants generate steam for steam turbines in thermal power plants. As a rule, such boiler houses are equipped with boilers of large and medium power, which produce steam with increased parameters.
Industrial heating boiler plants (usually steam) generate steam not only for industrial needs, but also for heating, ventilation and hot water supply.
Heating boiler plants (mainly hot water, but they can also be steam) are designed to service heating systems of industrial and residential premises.
Depending on the scale of heat supply, heating boiler houses are local (individual), group and district.
Local boiler houses are usually equipped with hot water boilers with water heating to a temperature of no more than 115 ° C or steam boilers with an operating pressure of up to 70 kPa. Such boiler rooms are designed to supply heat to one or more buildings.
Group boiler plants provide heat to a group of buildings, residential areas or small neighborhoods. They are equipped with both steam and hot water boilers with a higher heating capacity than boilers for local boiler houses. These boiler rooms are usually located in specially constructed separate buildings.
District heating boilers are used to supply heat to large residential areas: they are equipped with relatively powerful hot water or steam boilers.
Rice. 1.
Rice. 2.
Rice. 3.
Rice. 4.
Individual elements It is customary to conventionally show the schematic diagram of a boiler plant in the form of rectangles, circles, etc. and connect them with each other with lines (solid, dotted), denoting a pipeline, steam pipelines, etc. There are significant differences in the schematic diagrams of steam and hot water boiler plants. A steam boiler plant (Fig. 4, a) of two steam boilers 1, equipped with individual water 4 and 5 air economizers, includes a group ash collector 11, to which the flue gases go through a collecting hog 12. For suction of flue gases in the area between the ash collector 11 and chimney 9 installed smoke exhausters 7 with electric motors 8. For the operation of the boiler room without smoke exhausters installed dampers (dampers) 10.
Steam from the boilers through separate steam pipelines 19 enters the common steam pipe 18 and through it to the consumer 17. Having given off heat, the steam condenses and through the condensate pipe 16 returns to the boiler room to the collecting condensation tank 14. Through pipe 15, additional water from the water pipe or chemical water treatment is supplied to the condensation tank (to compensate for the volume not returned from consumers).
In the case when part of the condensate is lost at the consumer, from the condensation tank a mixture of condensate and make-up water is supplied by pumps 13 through the feed pipeline 2, first to the economizer 4, and then to the boiler 1. The air required for combustion is sucked in by centrifugal blowing fans 6 partially from the room boiler room, partly outside and through the air ducts 3 is supplied first to the air heaters 5, and then to the boiler furnaces.
The hot water boiler plant (Fig. 4, b) consists of two hot water boilers 1, one group water economizer 5 serving both boilers. Flue gases at the outlet of the economizer through the common collecting hog 3 go directly to the chimney 4. The water heated in the boilers enters the common pipeline 8, from where it is fed to the consumer 7. Having given off the heat, the cooled water is first sent through the return pipeline 2 to the economizer 5 , and then back into the boilers. Water in a closed loop (boiler, consumer, economizer, boiler) is moved by circulation pumps 6.
Rice. 5. : 1 - circulation pump; 2 - firebox; 3 - superheater; 4 - upper drum; 5 - water heater; 6 - air heater; 7 - chimney; 8 - centrifugal fan (smoke exhauster); 9 - fan for supplying air to the air heater
In fig. 6 shows a diagram of a boiler unit with a steam boiler having an upper drum 12. In the lower part of the boiler there is a furnace 3. For combustion of liquid or gaseous fuel, nozzles or burners 4 are used, through which the fuel together with air is fed into the furnace. The boiler is bounded by brick walls - lining 7.
When fuel is burned, the released heat heats the water to boiling in the tube screens 2 installed on the inner surface of the furnace 3 and ensures its transformation into water vapor.
Fig 6.
Flue gases from the furnace enter the boiler gas ducts formed by the lining and special partitions installed in the bundles of pipes. When moving, the gases wash around the bundles of pipes of the boiler and superheater 11, pass through the economizer 5 and the air heater 6, where they are also cooled due to the transfer of heat to the water entering the boiler and the air supplied to the furnace. Then, the significantly cooled flue gases are removed through the chimney 19 into the atmosphere by means of a smoke exhauster 17. Flue gases from the boiler can be discharged even without a smoke exhauster due to the natural draft generated by the chimney.
Water from the water supply source through the feed pipeline is pumped by the pump 16 into the water economizer 5, from where, after heating, it enters the upper drum of the boiler 12. The filling of the boiler drum with water is controlled by a water indicator glass installed on the drum. In this case, the water evaporates, and the resulting steam is collected in the upper part of the upper drum 12. Then the steam enters the superheater 11, where it is completely dried due to the heat of the flue gases, and its temperature rises.
From the superheater 11, steam enters the main steam line 13 and from there to the consumer, and after use it condenses and in the form of hot water (condensate) returns back to the boiler room.
Losses of condensate at the consumer are replenished with water from the water supply system or from other sources of water supply. Before being fed into the boiler, the water is subjected to appropriate treatment.
The air required for fuel combustion is taken, as a rule, from the top of the boiler room and supplied by the fan 18 to the air heater 6, where it is heated and then sent to the furnace. In boilers of small capacity, air heaters are usually absent, and cold air is supplied to the furnace either by a fan or by vacuum in the furnace created by the chimney. Boiler plants are equipped with water treatment devices (not shown in the diagram), instrumentation and appropriate automation equipment, which ensures their uninterrupted and reliable operation.
Rice. 7.
For the correct installation of all elements of the boiler room, use wiring diagram, an example of which is shown in Fig. nine.
Rice. nine.
Hot water boilers are designed to produce hot water used for heating, hot water supply and other purposes.
To ensure normal operation, boiler rooms with hot water boilers are equipped with the necessary fittings, instrumentation and automation equipment.
A hot water boiler house has one heat carrier - water, in contrast to a steam boiler house, which has two heat carriers - water and steam. In this regard, in a steam boiler room, it is necessary to have separate pipelines for steam and water, as well as tanks for collecting condensate. However, this does not mean that the schemes of hot water boiler houses are simpler than steam ones. Hot water and steam boilers are different in terms of the complexity of the device, depending on the type of fuel used, the design of boilers, furnaces, etc. ... All of them are connected by common communications - pipelines, gas pipelines, etc.
The device of boilers of lower power is shown below in paragraph 4 of this topic. In order to better understand the structure and principles of operation of boilers of different power, it is advisable to compare the device of these less powerful boilers with the device of the above-described boilers of higher power, and find in them the main elements that perform the same functions, and also understand the main reasons for the differences in designs.
3. Classification of boiler units
Boilers like technical devices for the production of steam or hot water are distinguished by a variety of design forms, principles of operation, used fuels and performance indicators. But according to the method of organizing the movement of water and steam-water mixture, all boilers can be divided into the following two groups:
Natural circulation boilers;
Boilers with forced movement of the heat carrier (water, steam-water mixture).
In modern heating and heating-industrial boiler houses, boilers with natural circulation are mainly used for steam production, and for the production of hot water - boilers with forced movement of the coolant, operating according to the direct-flow principle.
Modern steam boilers with natural circulation are made from vertical pipes located between two collectors (upper and lower drums). Their device is shown in the drawing in Fig. 10, a photograph of the upper and lower drums with pipes connecting them is shown in Fig. 11, and placement in the boiler room is shown in Fig. 12. One part of the pipes, called heated "riser pipes", is heated by the torch and combustion products, while the other, usually unheated part of the pipes, is located outside the boiler unit and is called "downpipes". In the heated riser pipes, the water is heated to a boil, partially evaporates and in the form of a steam-water mixture enters the boiler drum, where it is separated into steam and water. Through the lowering unheated pipes, water from the upper drum enters the lower collector (drum).
The movement of the coolant in boilers with natural circulation is carried out due to the driving pressure created by the difference in the weights of the column of water in the downward and the column of the steam-water mixture in the riser pipes.
Rice. ten.
Rice. eleven.
Rice. 12.
In steam boilers with multiple forced circulation, heating surfaces are made in the form of coils that form circulation circuits. The movement of water and steam-water mixture in such circuits is carried out using a circulation pump.
In once-through steam boilers, the circulation rate is unity, i.e. The feed water, when heated, is successively converted into a steam-water mixture, saturated and superheated steam.
In hot water boilers, when moving along the circulation circuit, water heats up in one revolution from the initial to the final temperature.
According to the type of heat carrier, boilers are divided into hot water and steam boilers. The main indicators of a hot water boiler are thermal power, that is, heating capacity, and water temperature; the main indicators of a steam boiler are steam capacity, pressure and temperature.
Hot water boilers, the purpose of which is to obtain hot water of specified parameters, are used to supply heat to heating and ventilation systems, domestic and technological consumers. Hot water boilers, which usually work according to the direct-flow principle with a constant water flow, are installed not only at CHPPs, but also in district heating, as well as heating and industrial boilers as the main source of heat supply.
Rice. 13.
Rice. fourteen.
According to the relative movement of heat exchanging media (flue gases, water and steam), steam boilers (steam generators) can be divided into two groups: water-tube boilers and fire-tube boilers. In water-tube steam generators, water and a steam-water mixture move inside the pipes, and the flue gases wash the pipes outside. In Russia, in the 20th century, Shukhov's water-tube boilers were mainly used. In fire-tube, on the contrary, flue gases move inside the pipes, and water washes the pipes from the outside.
According to the principle of movement of water and steam-water mixture, steam generators are subdivided into units with natural circulation and with forced circulation. The latter are subdivided into direct-flow and multiple-forced circulation.
Examples of placement in boiler rooms of boilers of different power and purpose, as well as other equipment, are shown in Fig. 14-16.
Rice. 15.
Rice. 16. Examples of placement of household boilers and other equipment
3.1. General -1
3.2. Purpose and classification of boiler units -2
3.3. The main types of boiler units -5
3.4. Hot water boilers -16
3.5. Block-modular boiler rooms -21
3.6. Energy saving in boiler rooms -26
3.7. Chemical water treatment -28
3.8. Review of some boiler plants in the Perm region -43
3.1. General information
The boiler plant consists of a boiler and auxiliary equipment. Devices designed to produce steam or hot water high blood pressure due to the heat released during the combustion of fuel, or heat supplied from extraneous sources (usually with hot gases), are called boiler units. They are divided respectively into steam boilershigh and hot water boilers. Boiler units that use (i.e. utilize) the heat of exhaust gases from furnaces or other main and by-products of various technological processes are called waste heat boilers.
The boiler includes: firebox, superheater, economizer, air heater, frame, lining; thermal insulation, sheathing.
TO auxiliary equipment include: draft machines, heating surface cleaning devices, fuel preparation and fuel supply devices, slag and ash removal equipment, ash collection and other gas cleaning devices, gas-air pipelines, water, steam and fuel pipelines, fittings, fittings, automation, instruments and control devices l protection, water treatment equipment and chimney.
Fittings include: control and shut-off devices, safety and water sample valves, pressure gauges and water indicating devices.
The headset includes: manholes, peepers, hatches, gates and dampers.
The building in which the boilers are located is called boiler room.
The complex of devices, which includes a boiler unit and auxiliary equipment, is called boiler plantcoy. Depending on the type of fuel burned and other conditions, some of these accessories may not be available.
Boiler plants supplying steam to turbines of thermal power plants are called energy. To supply steam to industrial consumers and to heat buildings, in a number of cases, special production and heating boiler installations are created.
Natural and artificial fuels (coal, liquid and gaseous products of petrochemical processing, natural and blast furnace gases, etc.), waste gases of industrial furnaces and other devices, solar energy, nuclear fission energy of heavy elements (uranium , plutonium), etc. Boiler plants with a capacity of more than 10 Gcal must necessarily have main and reserve fuel
The technological diagram of a boiler plant with a drum steam boiler operating on pulverized coal is shown in Fig. 3.1. Fuel from the coal warehouse after crushing is conveyed to the raw coal bunker by a conveyor 1, from which it is sent to the pulverization system with a coal grinding mill 2. Pulverized fuel with a special fan 3 transported through pipes in the air flow to the burners 4 furnace. boiler 5 located in the boiler room 14. Secondary air is also supplied to the burners by a blower fan 13 (usually through the boiler air heater 10). Water for feeding the boiler is supplied to its drum 7 by a feed pump 12 from the feed water tank; / having a deaeration device. Before water is supplied to the drum, it is heated in a water economizer 9 boiler. Evaporation of water takes place in a pipe system. Dry saturated steam from the drum enters the superheater 8, and then sent to the consumer.
The fuel-air mixture supplied by the burners to the combustion chamber (furnace) of a steam boiler burns out, forming a high-temperature (1500 ° C) torch that radiates heat to the pipes 6 located on the inner surface of the walls of the firebox. These are evaporative heating surfaces called shields. Having given part of the heat to the screens, flue gases with a temperature of about 1000 ° C pass through the upper part of the rear screen, the pipes of which are located here at large intervals (this part is called festoon), and wash over the superheater. Then the combustion products move through the water economizer, air heater and leave the boiler with a temperature slightly exceeding 100 ° C. The gases leaving the boiler are cleaned from ash in an ash collecting device 15 and a smoke exhauster 16 emitted into the atmosphere through the chimney 17. The pulverized ash caught from the flue gases and the slag that has fallen into the lower part of the furnace are removed, as a rule, in a stream of water through the channels, and then the resulting pulp is pumped out by special dredge pumps from the pumping room. 18 and is removed through pipelines.
The drum boiler unit consists of: a combustion chamber and gas ducts, a drum, heating surfaces under pressure of the working medium (water, steam-water mixture, steam), an air heater, connecting pipelines and air ducts. Pressurized heating surfaces include: water economizer, evaporative
elements formed mainly by firebox screens and festoons, and a superheater. All boiler heating surfaces, including the air heater, are usually tubular. Only a few powerful steam boilers have air heaters of a different design. The evaporating surfaces are connected to the drum and, together with the downpipes connecting the drum with the lower collectors of the screens, form a circulation circuit. Separation of steam and water takes place in the drum, in addition, a large supply of water in it increases the reliability of the boiler.
The lower trapezoidal part of the boiler unit furnace (see Fig. 3.1) is called a cold funnel - in it the partially sintered ash residue falling out of the torch is cooled, which in the form of slag falls into a special receiving device.
Oil-fired boilers do not have a cold funnel. The flue in which the water economizer and air heater are located is called convective(convection shaft), in it heat is transferred to water and air mainly by convection. Heating surfaces built into this flue and called tailings allow to reduce the temperature of combustion products from 500. – 7ОО ° С after the superheater to almost 100 ° С, ie. to make fuller use of the heat of the combusted fuel.
The entire pipe system and boiler drum are supported by a frame consisting of columns and crossbeams. The furnace and gas ducts are protected from external heat loss by lining - a layer of refractory and insulating materials. On the outside of the lining, the boiler walls have a gas-tight sheathing with a steel sheet in order to prevent excess air from sucking into the furnace and knocking out dusty hot combustion products containing toxic components.
3.2. Purpose and classification of boilers
The boiler unit is called an energy device with a capacity of D (t / h) to obtain steam with a given pressure (R, MPa) and temperature (t, ° С). This device is often called a steam generator, as it generates steam, or simply a steam boiler. If the end product is hot water of specified parameters (pressure and temperature), used in industrial technological processes and for heating industrial, public and frail buildings, then the device is called a hot water boiler. Thus, all boilers can be divided into two main classes: steam and hot water.
By the nature of the movement of water, steam-water mixture and steam, steam boilers are subdivided (Fig. 3.2):
on drum with natural circulation;
drum with multiple forced circulation;
straight-through.
V drum boilers with natural circulation(Fig. 3.3) due to the density difference of the steam-water mixture in the left pipes 2 and liquids in the right pipes 4 the steam-water mixture in the left row will move up, and the water in the right row will move down. The pipes of the right row are called drop pipes, and the pipes of the left row are called lifting (screen) pipes.
The ratio of the amount of water passing through the circuit to the steam capacity of the circuit D over the same period of time, the circulation rate TO NS . For boilers with natural circulation TO c ranges from 10 to 60.
The difference in the weights of the two columns of liquids (water in the lowering and steam-water mixture in the lifting pipes) creates a driving head of water circulation in the boiler pipes:
Δp= gh (Rw - r cm), N / m 2,
where h - contour height, m; p in, p cm - density (bulk density) of water and steam-water mixture, kg / m 3.
The driving head of the circulation is used to overcome the resistance to movement of water and steam-water mixture through the pipes, as well as to communicate the acceleration of the steam-water mixture due to the increase in the volume of liquid that occurs during vaporization in the riser pipes.
V boilers with forced circuitlesion movement of water and steam-water mixture (see Fig. 3.2, b) is carried out forcibly with the help of a circulating pump TsN, the driving head of which is designed to overcome the resistance of the entire system.
V once-through boilers(see fig. 3.2, v) no circulation circuit, and multiple circulation of water, no drum, water is pumped by a feed pump through an economizer, evaporating surfaces and a superheater included
Steam boiler unit (steam generator) is characterized by steam capacity (t / h or kg / sec), pressure (kN / sh2< МН/м 2), температурой производимого пара и температурой питательной воды. Эти параметры в России регламентируются стандартами (табл. 3.1).
Since the steam generator is designed to convert the heat contained in the fuel into potential energy and it is a kind of energy converter, therefore it can also be characterized by power (kW or MW). In terms of steam capacity, boilers of low steam capacity (up to 20 ... 25 t / h), medium steam capacity (from 35 ... 50 to 160 ... 220 t / h) and high steam capacity (from 220 ... 250 t / h and more) are distinguished.
Table 3.1
By the pressure of the steam produced, boilers are distinguished: low pressure(up to 1.37 MN / m 2), medium pressure (2.35 and 3.92 MN / m 2) high pressure (9.81 and 13.7 MN / m 2) and supercritical pressure (25.1 MN / m 2). The border separating low pressure boilers from medium pressure boilers is arbitrary.
Boiler units produce either saturated steam or steam superheated to different temperatures, the value of which depends on its pressure. At present, the steam temperature in high-pressure boilers does not exceed 540 ... 570 "C. The feed water temperature, depending on the steam pressure in the boiler, ranges from 50 to 260 "C.
Hot water boilers are characterized by their heating capacity (kW or MW, in the MKGSS system - Gcal / h), temperature and pressure of heated water, as well as by the kind of metal from which the boiler is made.
By the type of metal, cast iron and steel hot water boilers are distinguished. Cast iron boilers are designed for heating individual buildings and are designed for small heating capacities, not exceeding 1.2 ... 1.6 MW, for heating water with a pressure not higher than 300 ... 400 kN / m 2 to a temperature of 115 "C. Steel boilers are designed for large heating capacities from 4.75 to 210 MW and are installed in large district and district boiler houses to supply heat to large residential areas. In addition, hot water boilers with a heating capacity of 35 MW and above are also installed at CHPPs instead of peak heating water heaters.
3.3. The main types of boiler units
Power boiler units. Boiler units with a capacity from 50 to 220 t / h at a pressure of 3.92 ... 13.7 MN / m 2 are performed only in the form of drum units operating with natural water circulation. Steam units with a capacity from 250 to 640 t / h at a pressure of 13.7 MN / m 2 are performed both in the form of drum and direct-flow, and boiler units with a steam capacity of 950 t / h and higher at a pressure of 25 MN / m 2 -. Only in the form of direct-flow ones, since natural circulation cannot be carried out at supercritical pressure.
A typical profile of a boiler unit with a steam capacity of 50 ... 220 t / h for a steam pressure of 3.97 ... 13.7 MN / m 2 at an overheating temperature of 44O ... 57O ° C (Fig. 6.4) is characterized by the arrangement of its elements in the form of the letter "P", in as a result, two passages of flue gases are formed. The first move is a shielded firebox, which determined the name of the type of boiler unit. The shielding of the furnace is so significant that in it all the heat required to convert the water entering the boiler drum into steam is transferred to the screen surfaces. As a result, the need for boiling convective heating surfaces disappears; only the superheater, water economizer and air heater remain convective heating surfaces in boiler units of this type.
Coming out of the combustion chamber , flue gases enter a short horizontal connecting flue where the superheater is located , separated from the combustion chamber only by a small scallop . After that, the flue gases are directed to the second - descending - gas duct, in which water economizers and air heaters are located in the cut. . The burners can be either swirling with an arrangement on the front wall or on the side walls opposite, or corner (as shown in the figure).
For boiler units with a steam capacity of 320 ... 640 t / h and a steam pressure of 13.7 MN / m 2, as a rule, they retain a U-shaped arrangement, although in some cases a T-shaped arrangement appears. The implementation of the superheater is becoming more and more complex. Semi-open top 6 and regenerative air heaters are becoming more widely used.
Boiler units with a steam capacity of 950, 1600 and 2500 t / h and a steam pressure of 25 MN / m 2 are intended for operation in a block with turbines with a capacity of 300, 500 and 800 MW. The layout of the boiler units of the indicated steam capacity is U-shaped with an air heater placed outside the main part of the unit. Steam superheating is double: its pressure after the primary superheater is 25 MN / m 2 and the temperature is 565C, after the secondary - 4 MN / m.
Waste heat boilers, О They represent a special group of boilers designed to use the heat of flue gases from various industrial furnaces. Waste heat boilers generally generate steam. At high temperatures of gases (more than 900 ° C), these boilers are equipped with radiation (screen) heating surfaces and have the same layout as a conventional steam boiler (Fig. 3.7), but without a cold funnel (instead of it, there is a gas inlet). An air heater may also be absent if there is no need for hot air. Such a radiation chamber of the utilizer acts as the first radiation gas cooler.
If the gas discharged from technological installations does not contain combustible components, then such a boiler does not have burners. These boilers operate with natural or forced circulation and have practically all the details of the previously described boiler units. They are equipped with screens, drums, superheaters, water economizers and air heaters. If there are combustible components in the process gases supplied to the boiler, their preliminary afterburning is organized.
At gas temperatures below 900 ° C, only convective heating surfaces are usually used in waste heat boilers. These units do not have a radiation chamber, but are entirely made of coils (see Fig. 3.4).
Steam with a pressure of 3.92 MN / m 2, superheated to 450 ... 470 "C, can be used for energy purposes.
Waste heat boilers are produced with natural and forced water circulation. Natural circulation boilers are mainly used in furnaces with a flue gas temperature of 800 ... 1000 ° C and above, which is associated with the conditions for ensuring reliable circulation.
Currently, a series of standardized boilers of the KU type is being produced, installed behind the furnaces of ferrous metallurgy plants. All boilers of this series, like most other coil heat exchangers, operate with multiple circulation of water through the evaporating surfaces (see Fig. 6.7).
The water heated in the water economizer 5 is fed into the drum 3, where does it come from circulation pump 2 and is pumped through the evaporative coils 4. The steam / water mixture is then returned to the drum where the steam is separated from the water. The water is again directed to the circulation pump, and the separated steam - to the superheater 1, which is installed in an area of increased gas temperature.
Usually, the evaporating surface is divided into two or three parallel-connected sections to reduce their hydraulic resistance (and the pressure of the circulation pump), and one of the sections is often placed first along the gas path, before the superheater, to protect it from too hot incoming gases.
Steam boilers for industrial boiler houses. Industrial boilers supplying industrial enterprises with low-pressure steam (up to 1.4 MPa) are formed by steam boilers manufactured by the domestic industry with a capacity of up to 50 t / h. Boilers are manufactured for burning solid, liquid and gaseous fuels.
On a number of industrial enterprises in case of technological necessity, medium pressure boilers are used. In fig. 6.10 presented general form single-drum vertical single-tube boiler BG-35 with a capacity of 35 t / h, with an excess pressure in the drum of 4.3 MPa (steam pressure at the outlet of the superheater is 39 atm) and an overheating temperature of 440 ° C. The boiler consists of two vertical gas ducts - lifting and lowering, connected in the upper part by a small horizontal gas duct. This boiler layout is called U-shaped.
The boiler has a highly developed screen surface and a relatively small convective beam. Screen tubes D 60 x 3 mm are made of steel grade 20. Rear screen tubes in the upper part are bent, forming a scallop. The lower ends of the wall tubes are expanded into collectors, and the upper ends into a drum.
The screen collectors are spring supported so that the entire piping system can expand freely when heated.
Superheater 14 vertical type, made of pipes D 38x3 mm, located in a horizontal gas duct and consists of two parts. A surface desuperheater is included in the cut between the first and second parts of the superheater 13 (steam superheat temperature controller).
Tail heating surfaces - coil water economizer 15 and tubular air heater are located in the lower gas duct of the boiler. 17.
The layout of the tail heating surfaces depends on the type of fuel and the way it is burned. In fig. 3.5, a water economizer is placed first in the course of gases, followed by an air heater. This arrangement of the tail surfaces is called single-tier. It is used for high-grade fuels. The coil economizer is made of steel pipes Ø 32x3 mm. The arrangement of the pipes of the economizer coils is staggered.
The main type of low-capacity steam boilers, now widespread in various industries industry, transport, utilities and agriculture (steam is used for technological and heating and ventilation needs), as well as at low-power power plants, are vertical water-tube boilers DKVR (two-drum verbal boiler, reconstructed). The characteristics of the DKVR boilers are given in table. 6.2 Boilers DKVR (Biysk boiler plant) were originally intended for burning solid fuel, but then adapted for burning liquid and gaseous fuel ("Uralkotlomash").
Here are the characteristics of the DKVR-20-13 boiler used at the Permsky pig farm.
|
Name |
Dimension |
Quantity or characteristic |
|
|
Saturated steam temperature | |||
|
Feed water temperature | |||
|
Burning method |
Chamber using combined gas-oil burners |
||
|
Gas consumption for the boiler | |||
|
Fuel oil consumption for the boiler |
In the DKVR-20 boiler, the walls of the furnace are closed shield tubes(Figure 6.11). A mine partition is installed on the inclined part of the rear screen , dividing the combustion chamber into the actual combustion chamber and the afterburner chamber . From the afterburning chamber, the flue gases are fed into the located between the upper and lower drums convective bundle, divided by partitions into three horizontal gas ducts, in which the pipes are washed by a transverse flow of gases. There are three gas-oil burners on the front wall of the combustion chamber. The drums of boilers for a pressure of 13 kgf / cm 2 have the same inner diameter (1000 mm) with a wall thickness of 13 mm.
For inspection of drums and devices located in them, as well as for cleaning pipes with cutters, there are manholes on the rear and front bottoms. To monitor the water level in the upper drum, two water-indicating glasses and a level switch are installed. In boilers with a long drum, the water indicating glasses are attached to the cylindrical part of the drum, and in boilers with a short drum, to the front bottom. From the front bottom of the upper drum, impulse tubes are diverted to the power regulator. In the water space of the upper drum, there is a feed pipe and a pipe for continuous blowdown; in the steam volume - separation devices. The lower drum contains a perforated pipe for periodic blowdown, a device for warming up the drum during firing up and a nozzle for draining water.
Side screen collectors are located under the protruding part of the upper drum, near the side walls of the lining. To create a circulation loop in the screens, the front end of each screen collector is connected by an unheated drop pipe to the upper drum, and the rear end is connected by a bypass pipe to the lower drum.
Water enters the side screens simultaneously from the upper drum through the front downcomers, and from the lower drum through the bypass. Such a power supply scheme for the side screens increases the reliability of operation at a low water level in the upper drum, and increases the circulation rate.
Screen pipes of DKVR steam boilers are made of 512.5 mm steel.
In boilers with a long upper drum, the wall tubes are welded to the screen collectors, and they are expanded into the upper drum.
The pitch of the side screens for all DKVR boilers is 80 mm, the pitch of the rear and front screens is 80 130 mm.
Boiler tube bundles are made of bent seamless steel tubes with a diameter of 512.5 mm.
The ends of the boiling pipes of DKVR-type steam boilers are attached to the lower and upper drums by means of rolling.
The circulation in the boiler pipes occurs due to the violent evaporation of water in the front rows of the pipes, because they are located closer to the firebox and are washed by hotter gases than the rear ones, as a result of which the water in the rear pipes located at the outlet of the gases from the boiler does not go up, but down.
The combustion chamber, in order to prevent the flame from being drawn into the convective bundle and to reduce the loss with entrainment from mechanical incompleteness of fuel combustion, is divided by a partition into two parts: a furnace and a combustion chamber. The partitions of the boiler are made in such a way that the flue gases wash the pipes with a transverse current, which promotes heat transfer in the convective bundle.
Superheater tubes are located at the beginning of the convective bundle. (a superheater in DKVR boilers may be absent), and then - pipes of the boiler bundle. A steam-water mixture enters the collectors, water separated from the mixture through the circulation pipe 9 a 9 descends into the lower collectors, and steam with an abundant amount of water droplets enters two external vertical cyclones through steam exhaust pipes . Water separated in cyclones through drain pipes enters the lower collectors of the screens. Steam from external cyclones through pipes goes to the separation device inside the drum, and from there to the boiler superheater or directly to the heat consumer (if there is no superheater in the boiler). Feed water enters the boiler through the valve . The boiler is mounted on a support frame.
The efficiency can vary from 75 to 91% depending on the flue gas temperature, since DKVR boilers can be installed either with or without economizers. Economizers heat the feed water to 138-165 ° C by cooling the exhaust gases to 140-180 ° C.
A modern boiler unit is served by a number of auxiliary mechanisms and devices. These include: gas and fuel oil supply systems, a gas control station, smoke exhausters and blowing fans, chemical water treatment, feed and water heating plants.
Water from the deaerator tank enters the feed pumps of the CNSG - 105/195 brand and then is fed to the steam boilers.
The feed water, after being heated in an economizer located at the outlet of flue gases from the convective part of the boiler, enters the feed pipe located in the water space of the clean section of the upper drum.
The water economizer (steel, monoblock, not switched off by flue gases and by feed water) is intended for heating feed water with flue gases.
To burn gas, the boilers are equipped with GMGB gas-oil burners. The main components of the burners are gas part consisting of an annular gas manifold (7) with holes and a supply pipe. The design of the gas section and the cross-section of the collector significantly affect the formation of the gas-air mixture. It is designed so that the collector is at the same time a cylindrical section of the lance (loophole). The gas outlet openings in the manifold are located in one row. The cross-section and spacing of the gas holes are calculated taking into account the optimal introduction of gas jets into the air flow.
The vane swirler is one of the main units in the flow path of the air guide device (abbreviated VNU), formed by rotary profiled blades, a flame stabilizer (diffuser) and a lance (embrasure).
The profile swivel blades make it possible to bring the sawing bodies as close as possible to the air-guide blades and, therefore, to extend the residence time of the fuel particles in the swirling air flow, to reduce the speed of the air supplied for combustion (the resistance of the VNU), while maintaining the economic indicators of the combustion process.
Using the swing lever (Fig. 2, item 5), the blades of the vane swirler are opened and closed.
The flame stabilizer is an air guide assembly and is a conical shield located at the torch root. On the side of the screen facing the combustion space, during the passage of air, a low pressure area is created, thereby preventing pulsation and detachment of the flame at high air velocities and ensuring the stabilization of the combustion process. The stabilizer has several tangential slots through which the required amount of air enters the initial zone of mixture formation (flame root).
The lance is part of the air guide device and is a continuation of the flow path of the burner. It must be made of refractory material. The lance is not included with the burner.
Rice. 2 Gas-oil burner GMGB with ignition-protective device
1-oil nozzle, 2-gas part, 3-blade swirler,
4- flame stabilizer, 5- blade rotation lever, 6- plug,
7- ignition protection device, 8- gas manifold, 9- frame, 10- flange.
DKVR boilers can be used as hot water boilers. For this, a steam-water heater is installed above the boiler, which is included in the boiler circulation circuit. In this case, the steam, heating the mains water, condenses, and the condensate flows by gravity from the heater into the lower drum of the boiler.
Disadvantages of DKVR boilers:
1) significant suction of air into the gas duct, therefore, the excessive consumption of fuel is from 2% to 7%, and below the efficiency.
2) insufficient degree of factory readiness, therefore, long terms of installation.
Biysk boiler plant and other plants are currently producing boilers of the DE and KE type (DE with a capacity from 1 to 25 t / h; KE with a capacity from 2.5 to 25 t / h, a pressure of 1.4 MPa (14 kgf / cm 2)), as well as other boilers (Table 3.3).
Table 3.3
Parameters and nominal performance of low and medium pressure steam boilers
according to GOST 3619-89
|
Ratings | |||||
|
temperature |
Rated gfhjghjbpdjlbntkmyjcnm |
||||
|
Standard size |
enthalpy of vapor. |
steam capacity l.4- " |
|||
|
lingering steam. |
Char temperature, ° С |
D nom, kg / s |
|||
|
Pr 0.16-9 + Pr 1-9 * |
174.5 (saturated) |
0.044; 0.069, C |
|||
|
E 0.25-9 + E 10-9 " |
174.5 (saturated) |
0,069; 0,111;0,193 |
|||
|
0,278; 0,444;0,694 |
|||||
|
1,11. 1,81.2.71 |
|||||
|
E 4-14 + E 35-14 |
194 (saturated) or |
1,14; 1,81; 2.78.4.44 |
|||
|
225 (superheated) | |||||
|
E 50-14 + E 100-14 |
13,9; 20,8;27,8 |
||||
|
E 10-24 + E 35-24 |
221 (saturated) or |
2800 or 2887 |
2,78; 6,94; 9,72 |
||
|
250 (superheated) | |||||
|
E 50-24 + E 160-24 |
13,9; 27,8; 44,4 |
||||
|
E 10-40 + E 75-40 |
2,78; 4,44; 6,94; 9,72 |
||||
* Pr - straight-through.
** E - natural circulation
Here is information on the DE-25-24-250 GM boiler, five of which are installed in the boiler room of Sibur-Khimprom OJSC
Steam boilers E (DE) are designed to generate saturated or superheated steam used for the technological needs of industrial enterprises, as well as heating, ventilation and hot water supply systems.
Double-drum vertical water-tube boilers are made according to the "D" design, a characteristic feature of which is the lateral arrangement of the combustion chamber relative to the convective part of the boiler.
The main components of the boilers are the upper and lower drums, the convective bundle and the left furnace wall (gas-tight partition) forming the combustion chamber, the right and rear furnace walls, as well as shielding pipes of the front wall of the furnace.
In all standard sizes of boilers, the inner diameter of the upper and lower drums is 1000 mm. The length of the cylindrical part of the drums increases with an increase in the steam output of the boilers from 2250 mm for boilers of 4 t / h to 7500 mm for boilers of 25 t / h. The distance between the axles of the drums is 2750 mm.
The drums are made of steel sheet in accordance with GOST 19281-89 and GOST 5520-79 from steel grades 16GS and 09G2S GOST 19281-89 or with a combination of these steel grades and have a wall thickness of 13 and 22 mm for boilers with a working absolute pressure of 1.4 and 2.4 MPa (14 and 24 kgf / cm 2).
For access to the inside of the drums, there are manholes in the front and rear bottoms.
The convective bundle is formed by vertical pipes 51x2.5 mm located along the entire length of the cylindrical part of the drums, connected to the upper and lower drums.
The convective beam width is 1000 mm for boilers with a steam capacity of 10; 25 t / h and 890 mm for other boilers.
The longitudinal pitch of the tubes of the convective bundle is 90 mm, the transverse one is 110 mm (except for the average pitch located along the axis of the drums, equal to 120 mm). The pipes of the outer row of the convective bundle are installed with a longitudinal pitch of 55 mm; at the inlet to the drums, the pipes are bred into two rows of holes.
In convective bundles of boilers 4; 6.5 and 10 t / h, longitudinal cast iron or stepped steel partitions are installed. Boilers 16 and 25 t / h have no baffles in the bundle.
The convective bundle is separated from the combustion chamber by a gas-tight partition (left combustion wall), in the rear part of which there is a window for gases to enter the bundle.
The pipes of the gas-tight partition, the right side screen, which also forms the floor and ceiling of the combustion chamber, and the pipes for the shielding of the front wall, are introduced directly into the upper and lower drums. Transverse section the combustion chamber is the same for all boilers. Its average height is 2400mm , width -1790 mm. The depth of the combustion chamber increases with an increase in the boiler steam output from 1930 mm for DE-4 t / h to 6960 mm for DE-25 t / h.
Pipes of the right combustion wall 51x2.5 mm are installed with a longitudinal pitch of 55 mm; at the inlet to the drums, the pipes are bred into two rows of holes.
Shielding of the front wall is made of pipes Ø51x2.5 mm.
The gas-tight partition is made of pipes Ø51x2.5 mm or Ø51x4 mm, installed with a pitch of 55 mm. At the inlet to the drums, the pipes are also bred into two rows of holes. The vertical part of the partition is sealed with metal spacers welded between the pipes. Sections of piping at the inlet to the drums are sealed with metal plates and chamotte concrete welded to the pipes.
The main part of the pipes of the convective bundle and the right furnace wall, as well as the pipes for shielding the front wall of the furnace, are connected to the drums by rolling. To increase the strength of the rolling joints, one annular groove is rolled in the walls of the drum holes drilled for the tubes to be rolled. When rolling, the metal of the pipe fills the recess, creating a labyrinth seal.
The pipes of the gas-tight partition are connected to the drums by electric welding or rolling, part of the pipes of the gas-tight partition, the right furnace wall and the outer row of the convective bundle, which are installed in the holes located in the welded seams or near the seam zone, are attached to the drum by electric welding or are rolled.
The rear screen of the firebox can be made in two versions:
1. Pipes of the rear screen of the furnace Ø51x2.5 mm, installed with a pitch of 75 mm, are welded to the upper and lower collectors of the screen Ø159x6 mm, which in turn are welded to the upper and lower drums. The ends of the rear screen collectors on the side opposite to the drums are connected by an unheated recirculation pipe Ø76x3.5 mm; to protect the recirculation pipes and collectors from thermal radiation, two Ø51x2.5 mm pipes are installed at the end of the combustion chamber, connected to the drums by rolling;
2. C-shaped pipes Ø51x2.5 mm, forming the rear screen of the furnace, are installed with a pitch of 55 mm and connected to the drums by rolling.
On boilers 16 and 25 t / h at pressures of 1.4 and 2.4 MPa with superheating of steam at 225 ° C and 250 ° C, vertical superheaters, drained, from two rows of pipes Ø51x2.5 mm. Pipes of the outer row, when entering the collectors Ø159x6 mm, are cased up to 38 mm. A two-stage superheater is located at the beginning of the convective bundle (opposite the exit window from the furnace). The outer row of the superheater, made of cased pipes, simultaneously serves as a part of the enclosing wall of the boiler block. Saturated steam from the upper drum is directed by bypass pipes 108x4.5 mm to the upper collector of the first superheat stage, located second along the gas flow. Having passed the pipes of the first stage of overheating, the lower collector Ø159x6 mm and pipes of the second stage of superheating, steam is supplied to the outlet through the upper collector Ø159x6 mm.
Boilers with steam generating capacity 4; 6.5 and 10 t / h are made with a one-stage evaporation scheme. In boilers 16; 25 t / h - two-stage evaporation scheme. The second stage of evaporation, with the help of transverse partitions in the drums, includes the rear part of the left and right screens of the furnace, the rear screen and a part of the convective bundle located in the zone with a higher temperature of gases. passing through the transverse partition of the upper drum. The circuit of the second stage of evaporation has unheated downpipes Ø159x4.5 mm. The downstream link of the circulation circuits of the boilers is 4; 6.5 and 10 t / h, and the first stage of evaporation of boilers 16 and 25 t / h are the least heated rows of tubes of the convective bundle in the course of gases.
In the water space of the upper drum there are a feed pipe and baffle plates, in the steam volume there are separation devices. The lower drum contains a device for steam heating of water during firing up, a perforated blowdown pipeline and pipes for water drainage.
As primary separation devices, baffle shields and guide caps installed in the upper drum are used, which ensure the supply of the steam-water mixture to the water level. A perforated sheet and louvered separator are used as secondary separation devices.
When assembling steam separation devices, special attention should be paid to creating density at the junction of the baffle plates with each other and at the points of their attachment to the half-couplers, as well as at the points of attachment of the guide visors - a strip with pins and install new paronite gaskets lubricated with graphite.
If it is necessary to adjust the water-chemical regime of the boilers, the introduction of phosphates should be provided in the feed line between the economizer and the boiler. On boilers with a steam capacity of 4; 6.5 and 10 t / h, continuous blowing is provided from the lower drum and intermittently from the lower collector of the rear screen (in the case when the rear screen has a collector). On boilers with a steam capacity of 4; 6.5 and 10 t / h, in which the rear screen of the furnace is made of C-shaped pipes Ø51mm, the periodic blowdown of the boilers is combined with the continuous blowdown carried out from the front bottom of the lower drum, it is recommended to cut the pipeline in between the shut-off and regulating body on the continuous blowdown line.
Boilers with a steam capacity of 16 and 25 t / h have continuous blowing from the second evaporation stage (salt compartment) of the upper drum and periodic blowing from the clean and salted compartments of the lower drum, as well as the lower header of the rear screen (in the case when the rear screen has a collector).
Flue gas outlet from boilers with steam capacity 4; 6.5 and 10 t / h is carried out through a window located on the rear wall of the boiler. On boilers with a steam capacity of 16 and 25 tons, the flue gas outlet is through a window in the left side wall of the boiler at the end (in the direction of the gases) of the convective bundle.
To clean the outer surface of the convective bundle pipes from deposits, steam-mechanical blowers or gas pulse cleaning devices (GIO) can be used. The blower has a pipe with nozzles, which must be rotated during blowing. The outer part of the appliance is attached to the casing of the left convective wall of the boiler. The rotation of the blower tube is done manually using a handwheel and a chain.
For blowing, saturated or superheated steam of operating boilers at a pressure of at least 0.7 MPa is used. The GIO device consists of a gas and air mixer, a pulse chamber, an ignition and control unit (BZU).
The work of the GMO is carried out as follows: gas (natural, propane, hydrogen, acetylene) is supplied to the mixer of the installation from the shop gas pipeline or from cylinders, and air (compressor, from a blower or fan) is introduced there in a ratio close to stoichiometric.
The mixture is fed through the mixing line to impulse chamber... After filling the chamber with a mixture, a pulse is supplied from the BZU high voltage(5-10 kilovolts) to the ignition source (car candle). The flame, passing through the mixture line, which also performs the function of the flame line, self-accelerates to the transition to the detonation combustion region and causes an explosion of the gas-air mixture in the pulse chamber (about 1 ms); at the exit from the chamber, a high-power shock wave is generated with a significant pressure drop at the front. Entering the boiler flue through the exhaust nozzle, the shock wave destroys and knocks deposits off the heating surfaces.
The number of explosive impulses and their frequency are set by the BZU. To remove soot deposits from the convective beam, hatches are installed on the left side of the boiler.
All boilers have three "peephole" hatches - two on the right side and one on the rear walls of the combustion chamber.
The hole in the explosive valve or the lance of the burner can serve as a manhole into the furnace. Dense shielding of the side walls (relative pipe spacing S = 1.08), the ceiling and floor of the combustion chamber makes it possible to use lightweight insulation with a thickness of 100 mm on boilers, laid on a layer of chamotte concrete with a thickness of 15-20 mm, applied along the grid. Asbestos-vermiculite slabs or equivalent in terms of thermophysical properties are used as insulation.
The lining of the front wall is made of class A or B refractory fireclay bricks, diatom bricks, insulation boards; the lining of the back wall is made of refractory fireclay bricks and insulation boards.
To reduce air suction, the insulation outside is covered with a metal sheet sheathing 2 mm thick, which is welded to the frame. As insulation on these boilers, mullite-silica felt MKRV-200 GOST 23619-79 and mineral wool of increased temperature resistance TU36.16.22-31-89 are used, laid between dense heating enclosing surfaces and boiler casing.
To seal the annular gaps at the entrance to drums, in explosive valves, burner flanges, manhole covers and other units, asbestos cardboard KAON-1-5 GOST 2850-80 and asbestos cord SHAON 22 GOST 1779-83 are used.
Sheathing sheets of boiler blocks supplied in insulation have a thickness of 3 mm, 2 mm - for boilers supplied without insulation, and are welded along the entire contour of abutment to the frame elements.
The support frame takes up the load from the boiler pressure elements, boiler water, as well as the strapping frame, insulation and sheathing.
The load from the boiler pressure elements and the boiler water is transferred to the support frame through the lower drum.
To install the lower drum, the front and rear cross beams with support cushions are provided in the support frame design, as well as supports - two to the right of the drum (from the furnace side) on the cross beams and two to the left of the drum on the longitudinal beam.
The lower drum at the front of the boiler is fixed motionless by welding the drum to the transverse beam of the support frame through the ring and fixed supports. The frame and casing on the side of the boiler front are also fixed to the lower drum. Thermal expansion of the lower drum is provided towards the rear bottom, for which the rear supports are movable. On the rear bottom of the lower drum, a benchmark is installed to control the thermal expansion of the drum (boiler). Installation of benchmarks to control the thermal expansion of boilers in the vertical and transverse directions is not required, since the design of the boilers provides thermal movement in these directions.
For the combustion of heating oil and natural gas, gas-oil burners GMP and GM are installed on the boilers.
The main units of the burners are the gas part, the vane for air swirling, the nozzle unit with the main and reserve steam-mechanical nozzles and flaps, which serve to close the openings of the removed nozzle. At the front of the burner, a “peephole” and an ignition-protective device are provided.
The combustion chamber of two-stage fuel combustion, installed on boilers of 25 t / h, includes an outer casing, inner and outer shells, and a tangential air swirler.
Fuel in full is supplied to the GMP-16 burner installed from the front of the combustion chamber of two-stage fuel combustion. There, through the annular slot formed by the outer casing and the inner shell of the combustion chamber, primary air is supplied (70% of the total amount of air required for complete combustion of the fuel); secondary air (30% of the total) enters through the annular slot and the tangential swirler of the chamber. The directions of rotation of the primary and secondary air are the same.
The combustion chamber of two-stage fuel combustion is protected from flame radiation by refractory masonry made of class "A" chamotte.
The embrasure of the GMN-16 burner is conical type with an opening angle of 35 ° per side, for GM-10, GM-7, GM-4.5 and GM-2.5 burners - conical type with an opening angle of 25 ° per side. 7, GM-4.5 and GM-2.5 by air - vortex, the GM-10 burner - direct-vortex.
The steam boiler DE-25-24-250GM is divided into eight blocks according to the structural and technological characteristics. Physical and chemical processes inherent in it take place in each block.
In the furnace, fuel (gas) is burned and heat is transferred, both by radiation and convection. In this case, the process of fuel combustion is an order of magnitude faster than the process of transferring heat from flue gases to the coolant (water). In a radiation heat exchanger, the heat carrier is heated, partial vaporization and the rise of the vapor-liquid mixture into the evaporator drum due to the heat transmitted by the radiation.
In a convective lifting heat exchanger located along the course of flue gases, due to their heat, heating, partial vaporization and the rise of the mixture into the drum-evaporator take place.
In a two-stage superheater, saturated steam overheats and the steam pressure increases due to the heat of the flue gases. In the convective lowering heat exchanger, which is located behind the superheater, water is heated to the evaporation temperature and moved by natural convection from the upper drum to the lower one.
In a cast-iron-block economizer, water is preheated by flue gases to a temperature close to the boiling point.
Similarly to flue gases, you can consider the structural diagram of the boiler along the water flow.
The water enters the economizer, where it is preheated. In the evaporator drum, the formed steam and water are separated. The steam passes into the superheater and, when the operating pressure is reached, enters the main line, otherwise it is discharged to the purge plug.
The water remaining in the drum, subcooled to the boiling point, enters through the convective lowering heat exchanger into the lower drum-tank, where it is mixed. Further, the water, divided into two streams, enters the drum-evaporator through the radiation and convective lifting heat exchangers.
For steam boiler operation the most important parameter is the water level in the boiler drum. With a significant decrease in the level due to the capture of steam in the lowering system, the operation of the circulation circuit is disrupted. With an unacceptable increase in the level, water is thrown into the superheater, as a result of which the temperature of the steam drops sharply and the content of impurities in it increases. The position of the water level is regulated by changing the flow rate of the feed water. Modern means of automatic regulation make it possible, with the required accuracy and speed, to maintain the water level in the boiler drum constant.
A set of devices called Boiler plant.
When burning fuel, which is a carbonaceous and hydrocarbonaceous compounds of predominantly vegetable origin, the elements that make up the fuel combine with atmospheric oxygen, release heat and heat the combustion products. From the combustion products, thermal energy is transferred to the working fluid, which is usually water compressed to a pressure above atmospheric.
Thus, a certain amount of fuel and oxidizer (air) must be supplied to the boiler plant; ensure fuel combustion and transfer of heat from fuel combustion products to the working fluid and removal of fuel combustion products; supply a working fluid - water compressed to the required pressure, heat this water to the required temperature or turn it into steam, separate moisture from the steam, and sometimes overheat the steam, ensuring the reliable operation of all elements of the installation.
A device with a furnace for burning fuel, heated by the products of fuel combustion, designed to produce steam with a pressure above atmospheric and used. outside the device itself is called a Steam Boiler.
The same device, which serves for (obtaining hot water at a pressure greater than atmospheric pressure, is called Hot water boiler. Heat exchangers used for:
Heating water with fuel combustion products or other gases before water enters the boiler is called Water economizer;
Heating the steam leaving the boiler to a temperature exceeding the saturation temperature at the pressure in the boiler is called a Superheater;
Heating "the air supplied to the boiler furnace by the combustion products leaving the boiler (or from the water economizer) is called the Air heater.
The complex of all these heat exchange devices is called Boiler unit (steam generator).
To carry out the listed processes, the boiler plant includes:
Actually Kote l or boiler unit; Devices for supplying and preparing fuel for combustion - Fuel - supply and fuel preparation;
Installation for injecting the air necessary for combustion - Blower fan;
Equipment for the removal of focal fuel residues - sl and o - and Ash removal; *
Installation for suction of fuel combustion products from the installation - Smoke exhauster, in front of which devices are sometimes installed that separate ash from flue gases;
Flue gas evacuation facilities- chimney; Devices for the preparation of water by freeing it from harmful impurities - Equipment for chemical cleaning and deaeration;
Pumps for increasing the water pressure to more than the pressure in the boiler, and supplying it to the boiler unit - Feed pumps.
All these devices are housed in a special building called Boiler room, which includes premises for various auxiliary production services, workshops and utility rooms.
The boiler room is usually an industrial building that contains - *
Devices for storing a certain amount of fuel, mechanisms for preparing it for combustion and feeding it into the furnace;
Equipment for cleaning, storing, heating and pumping water for powering a boiler unit - heat exchangers, water treatment, deaerators, tanks, feed, network and other pumps - when installing steam and hot water boilers;
Various auxiliary machines and devices designed to ensure long-term and reliable operation of boiler units, including devices that allow you to control the progress of processes in the boiler unit and auxiliary equipment.
In addition to the above, the following are usually located outside the boiler house: devices for unloading and moving solid fuel around the warehouse, as well as sorting, crushing and feeding it into the boiler room;
Devices for receiving, unloading and supplying liquid fuel through tanks, devices for heating, filtration and transport to the boiler room;
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Rice. IN 1. Diagram of the device of an industrial boiler house operating on solid fuel,
/ - raw water heater; 2 and 3-d filters for chemical water purification; 4 - deaerator; 5 - condensate tank; 6 - pump for pumping condensate; 7 - conveyor for fuel supply; in the fuel bunker; 9 - feed water pump; / 0 - fuel feeder; // - mechanical chain grate; 12 - screens in the combustion chamber; 13 ~ lining; 14 - boiler drum; 15 - superheated steam collector; 16 - main shut-off valve; 17 - * ■ superheated steam temperature controller; 18 - superheater; 19 - water economizer; 20 - air heater; 21<- бункер для шлака; 22 - дутьевой вентилятор; 23 ~ батарейный золоуловитель; 24 - дымосос; 25 - дымовая труба; 26 - затворы на течках провала и золы; 27 - каналы для удаления шлака и золы водой; 28 щ главный паропровод и коллектор; 29 - редукционно-охладительная установка; 30 - арматура; Л г-? газоходы от котлоагрегате к дымовой
Pipelines supplying gas to the boiler room, and gas control points (GRP) for receiving, cleaning and reducing gas pressure in front of boilers;
Facilities for slag and ash removal from the boiler house and from its territory;
Warehouses for storage of materials (including fuel and lubricants) and spare parts required for the operation and repair of boiler plant equipment;
Devices for receiving and converting electrical energy consumed by a boiler plant. Sometimes hot water storage tanks are installed on the territory.
On the territory of the boiler house, the device of driveways and sites for various purposes, a green zone to protect the surrounding space from noise and pollution is regulated.
In fig. B-1 shows a diagram of the device of a production boiler house operating on solid fuel and supplying steam to a production enterprise , it will be heated in a heat exchanger, freed from some of its impurities and salts in chemical cleaning devices, and dissolved gases will be removed from it in a deaerator. After such preparation, the water is sent to the boiler unit by the feed pump.
The boiler unit consists of heating surfaces that evaporate water 12and superheating steam - superheater 18,heating water - water economizer 19,heating air - air heater 20.The boiler unit is lined 13,combustion device 11, Gas ducts 31,shut-off and control valves 30and etc.
The boiler unit consists of elements that are cylinders (pipes and vessels) of different diameters, connected to each other by welding or rolling ..
The main parts of the boiler are the drum 14,collectors 15and pipes.
To allow inspection and cleaning of drums and collectors, holes are made, called Manholes or hatches.
The internal volume of a steam boiler occupied by water is called in Nice space busy ferry - Steam space; the surface separating the steam space from the water space - Mirror of evaporation. In the steam space, devices are installed for separating moisture and steam, and sometimes an additional drum, called a Dryer, is installed.
When the steam boiler is operating, the water level in the drum fluctuates between the lowest and highest position.
The lowest permissible water level in the drums of steam boilers is established (determined) to exclude the possibility of overheating of the metal of the walls of the boiler unit elements and to ensure reliable water flow into the down pipes of the circulation circuits. Usually the lowest level is located 100 mm above the upper point of contact of the hot flue gases with the uninsulated wall of the boiler element.
Position of the highest The permissible water level in the drums of steam boilers is determined from the conditions for preventing the ingress of water into the steam line or superheater.
The volume of water contained in the drum between the highest and the lowest level determines the “supply reserve”, that is, the time that allows the boiler to work without water entering it.
The performance of the boiler unit is determined by the amount of heat or the mass quantity of steam received from the unit. Sometimes the size or performance of the boiler unit is characterized by the size of the heating surfaces. If heat is transferred to the working body from the products of fuel combustion by radiation, heating surfaces are called radiation - when heat is transferred by radiation (18) and convective Mi-pri heat transfer by contact(19, 20).Radiation surfaces when placed in a combustion chamber are called screens 12and they protect the walls from direct exposure to the radiating environment.
Combustion device 11serves for fuel combustion. In the combustion device can be carried out Layer combustion of fuel, when solid fuel is supplied for combustion to a grate of one type or another, or Kamernoe combustion, when fuel is burned in a flare when it is fed through burners or nozzles.
For. The fuel feeder 10 serves to supply solid fuel to the chain grate mechanically moving along the combustion chamber. The fuel is supplied to the feeder from the bunker 5. To load the bunker, it is used Conveyor 7, which is most often a belt conveyor.
On the way From the warehouse to the bunkers of the boiler house, metal objects, pieces of wood are removed from the fuel, and the fuel itself is crushed.
The air required for fuel combustion during layer combustion is supplied Fan22 under the grate. In some cases, it is preheated in an air heater 20.Sometimes part of the air is fed directly into the combustion chamber in the form of a "sharp" blast.
To remove slag and solid fuel particles that have fallen through the gratings, special containers are made in the lower part of the layered furnaces - Bunkers, gates and chutes26 located under and at the end of the grate.
In chamber furnaces for solid pulverized fuel in their lower part to collect slag from the walls covered with screens, so-called "cold" (slag) Funnels, under which slag bins are located.
The steam obtained in the evaporating heating surfaces, after drying and freeing of some of the salts, is sent to the Superheater18. In it, the water removed from the drum is evaporated and the steam is heated to a predetermined temperature.
The superheater consists of steel pipes made in the form of coils and connected by collectors 15, which are usually located outside the gas ducts. 'Sometimes some of the coils are placed in the combustion chamber. In the first case, the superheater is called convective 18, in the second - radiation. Since the superheater tends to be located in the region of relatively high temperatures, it is necessary to ensure its reliable operation under all operating modes by the correct choice of the speed of steam movement, its distribution over the coils, the selection and manufacture of pipes from metal with the proper properties. For reasons of reliability, superheater tubes are often made of special alloy steels. In order to exclude the possibility of increasing the temperature of the superheated steam, special regulators 17 are installed.
The introduced economizer 19 heats the feed water, and sometimes the water of heating networks. Water economizers of medium and high pressure boilers are made of steel pipes, for low pressure - from cast iron or steel pipes.
With partial evaporation of water in the pipes, the economizer is called ki Drinking. Cast iron water economizers are performed only non-boiling. Water is heated only to a temperature 20-40 ° C lower than the temperature of saturated steam in the drum 14 boiler.
The water economizer is supplied with water by a feed pump 9,due to the pressure of which, its forced movement in the economizer pipes is carried out.
An air preheater20 in small boilers is usually located after a water economizer. The air heater heats up the air that goes into the combustion chamber, under the grate and into the system for drying and grinding the fuel. In the case of burning fuels with a high moisture content or solid fuels in a chamber furnace, preheating the air is mandatory. When burning solid fuel in a bed or liquid and gaseous fuels in a chamber, in most cases for boiler units of low productivity, you can limit yourself to installing only a water economizer.
Air is supplied to the air heater by a blower fan 22 through the a-duct inlet ducts and is discharged to the combustion chamber (or to the fuel preparation system) by hot air ducts.
When burning gaseous fuel in the chamber, all the air is introduced through the burner, in which gas and air are mixed: when burning liquid fuel, all the air is also introduced through the burner, but the fuel is first converted into small droplets with the help of nozzles, which are then mixed with air.
If solid fuel is burned in a chamber furnace, the latter is preliminarily crushed in dust preparation plants to a particle size of several micrometers. In this case, one part of the air is introduced through the burner mixed with fuel (primary air) and the other through special devices in the same burner or next to it (secondary air). Sometimes part of the secondary air is separated and introduced through special devices at the bottom or on the back wall of the combustion chamber.
When burning solid fuels, in addition to flue gases, slag and ash are formed, which must be removed from the boiler unit and from the territory of the boiler house. Slag from the bunkers through the chute enters the removal device 27, passing in some cases a special crusher.
Slag removal systems can be mechanical, pneumatic and hydraulic; with small amounts of slag up to 0.06 kg / s (up to 200 kg / h), slag removal is used using trolleys with simple mechanization.
Together with the slag, ash is removed from the flue gases using Ash collecting plants23, placed in front of Smoke exhausters 24. Ash collecting installations and slag bunkers are separated from devices for ash removal by special gates 26.
The cooled and ash-free flue gases are removed through Chimneys25, the height of which is determined in such a way as to prevent unacceptable pollution of the air basin in the boiler room area.
Chimneys are made of steel, brick or reinforced concrete (with protective lining inside).
When boilers operate with a pressure in the combustion chamber higher than the pressure of atmospheric air or at low boiler room productivity, when the draft developed by the chimney is sufficient, the smoke exhausters are not installed. In very small boiler plants, it is sometimes possible to do without blowing fans.
Flue gases, passing through the flue gas ducts of the boiler unit, are sent to the ash collectors 23,then into hog 31,smoke exhausters 24and chimney 25.
Flue gases with a high temperature, obtained during the combustion of fuel in the combustion chamber, have a pressure that differs from atmospheric pressure.
To isolate flue gases from the external environment, use Lining13, which is made of bricks or refractory material, of metal shields with insulating plates. The lining can be based directly on the foundation, on metal structures - the frame, or mounted on the pipes of the screens of the combustion chamber and gas ducts.
The lining in different parts of the boiler unit is performed differently, since, for example, in the combustion chamber, the lining must be especially high-resistance, resistant to the chemical effects of slags, low-heat-conducting, cheap, simple in design, and sufficiently dense. Usually the lining is made of non-scarce materials.
The frame serves for fastening and supporting all elements of the boiler unit - drums, heating surfaces, pipelines, lining, stairs and platforms and is a metal structure, usually of frame type, connected by welding or bolts. The frame is fixed on the foundation, and sometimes it is performed combined with the frame of the building in which the boiler unit is installed.
G ar ni Tura are the devices that allow servicing the combustion chamber, grate grates and flue gas ducts of the "hotel unit - manholes, peepers and hatches with covers and doors for inspection and other devices for cleaning parts of the furnace and heating surfaces in the flue", dampers and dampers for regulating draft and blast and hatches for blowing.
The valve assembly30 of the boiler unit consists of devices that ensure its safe maintenance - safety valves, pressure gauges, lead-indicating devices, water sampling valves, regulating and shut-off devices for supplying, blowing and draining water, to disconnect the unit from the fuel, water and steam pipelines. The number of fittings and its mandatory types are regulated by the Rules of the USSR Gosgortekhnadzor [L. 1].
... TO It is customary to refer to auxiliary devices of a boiler plant as equipment on its territory for unloading, storing and supplying fuel. The boiler house can be supplied with fuel in various ways - by rail, by road and by pipelines. When burning solid and liquid fuels, the fuel economy "consists of devices and structures for unloading, receiving, leveling and supplying fuel to the bunkers of the boiler room or pipelines of the boiler room. *
When using liquid fuel supplied in railway or road tank cars, devices for unloading fuel - its discharge and storage are performed on the territory of the boiler house. Liquid fuel from storage is pumped over by pumps, heated to reduce (viscosity and filtered to release 01 Particles that can interfere with the operation of the injectors that prepare the fuel for combustion.
Gaseous fuel, supplied to the boiler house through the gas pipeline, enters the gas control point - hydraulic fracturing or gas control device - GRU, where its pressure is reduced to the required value. Further, the fuel enters - into the gas pipeline 35 boiler room to units with a chamber slipper (Fig. B-2) and to burners 36.
Devices for reducing the gas pressure in front of the boiler room, the mains for its removal and the distribution of pipelines in the "hotel" must be completed. in accordance with the instructions of the "Safety Rules in the Gas Industry" of the USSR Gosgortekhnadzor [L. 1].
Water intended for supply to steam boilers or heating networks and hot water. boilers must meet a number of technical, sanitary and economic requirements. In the case of water entering the hotel from the city (water supply system, treatment is reduced to softening it and reducing alkalinity in special filters 2 and 3 (see figure B-1); when using water from open reservoirs, the water must be purified from suspended solids.
Before entering devices for chemical treatment, water must be heated in heat exchangers 1.Contaminated condensate returned from process consumers is also treated.
Water and condensate prepared in one way or another are sent to devices for removing dissolved gases from them - deaerators 4. After deaerators with feed pumps 9water
It is sent to the “hotel unit” or to the heating networks by the top-up pumps.
| In small boiler rooms Sometimes for the supply of "feed water V Steam boiler Are used Reciprocating steam pumps or injectors. V Boiler rooms WITH Large steam boilers are usually used Centrifugal Electrically driven and steam driven pumps Turbines. For replenishment of heating networks with water, when steel hot water boilers are installed as a source of heat supply, / are used Centrifugal pumps are usually electrically driven. Cast iron Hot water boilers are allowed under certain conditions to be fed with water directly from the water supply.
Equipment placement Boiler plant in an open area Or V Building taken Call Layout. If all equipment Located inside Buildings as shown in fig. IN 2, Layout They are called closed; When placing a piece of equipment outside Buildings layout will be open.
Of the total, Descriptions “The hotel installation and its accessories should be What it is It is an industrial enterprise with cost accounting, for which it is customary to keep separate records and determine the cost of the generated heat energy.
All boiler plants with a pressure above 0.07 MPa (0.7 kgf / cm2) and a temperature above 11b ° C are subject to registration with a state organization that controls the correct design of the boiler unit, compliance with the established rules and laws of the equipment and the building of the boiler room, and Observance by service personnel Rules for the construction and safe operation of steam and hot water boilers of the USSR Gosgortekhnadzor, mandatory for all ministries and departments [L. 1]. Dimensions, materials from which the boiler houses are made, the size of the passages between the walls and equipment, as well as the distance to the farms AND Overlappings are determined by the Rules and Norms of Gosgortekhnadzor AND Gosstroy of the USSR [L. 2], which are mandatory for all ministries AND Departments.
Pipelines, s Help Which transport the coolant to consumers, Return Condensation or water at a lower temperature They are called heating networks. Their device, design, choice, ways of regulating work and other issues are studied in a special discipline - "Heat networks".
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