The design of cast iron boilers for coal
Cast-iron sectional boilers with an outer sheathing made of sheet steel work on coal. Thermal insulation made of sheet asbestos is laid between the sections of the boiler.
Flue gases from the boiler have a high temperature (about 250-400 C), which drastically reduces the efficiency of the boiler.
To reduce the temperature of flue gases and increase efficiency, it is recommended to connect a solid fuel boiler to a chimney through a heating shield.
In this case, when the draft deteriorates during the ignition of the boiler, the damper of the direct flue is opened and thereby the gases are directed into the chimney.
When the draft is established, the damper is closed, as a result of which the gases are redirected to the heating shield.
Still common in rural areas cast iron boilers following brands: KChMM, KChMM-2, KChM-1, KChM-2, KChM-3, etc. All boilers are designed for low pressure - 0.2-0.4 MPa.
Rice. 34. Sectional hot water boiler KCHMM-2
A - longitudinal section; B - cross section
Nominal efficiency - about 75% (when burning anthracite grade AO). Due to their heavy weight, cast iron boilers are quite laborious to install.
KCHMM-2 (Fig. 34) has 2-4 sections and a partially cooled grate (from alternately cooled and uncooled elements).
KChM-1 (Fig. 35) differs from KChMM-2 only in the number of cast-iron sections, which it has more.
KChM-2 (Fig. 36) has 2-8 sections (with a furnace opening in the front section) and gas ducts with flue gas flow extensions, which significantly increase the efficiency of the boiler.
Technical specifications solid fuel boiler KCHMM-2
Number of sections, pcs. - 4
Power, W - 9000
Overall dimensions, mm:
Length - 590
- width - 450
- height - 680
Grid area, m2 - 0.048
Boiler capacity, l - 16.7
Rice. 35. Sectional hot water boiler KCHM-1
A - longitudinal section; B - front view with internal ribs and struts with holes for the passage of gases.
KChM-2M Zharok-2 (Fig. 37) has a furnace for long-term combustion of solid fuel, which, if desired, can be converted to natural gas.
The combustion chamber is equipped with bypass kindling channels, which allow loading fuel to the full volume at a time and increasing the duration of the boiler without additional maintenance.
The bypass kindling channels are formed by additional ribs on the vertical pipes of cast iron sections and are not filled with fuel.
Rice. 36. Sectional hot water boiler KChM-2
1 - transformer; 2 - input return water; 3 - burner; 4 - electromagnetic valve; 5 - solenoid valve; 6 - gas supply; 7 - nipple; 8 - gas inlet; 9 - input hot water; 10 - traction chopper
The closed ash space formed by the ribs of the sections contributes to an increase in the gas density in the boiler, which makes it possible to regulate the air supply during kindling by opening the air collector cover at the required angle.
The KChM-2M Zharok-2 boiler is used for heating country houses with a construction volume of 300-900 cubic meters, equipped with a heating system with natural or forced circulation of the coolant.
Rice. 37. Hot water boiler KCHM-2M Zharok-2
1 - package of sections; 2 - lattice; 3 - asbestos cord; 4 - handle; 5 - air collector; b - ash box; 7 - screw M6x12; B - nut Mb; 9 - latch; 10 - washer; 11 - reflector; 12 - bottom door; 13 - bracket; 14 - right wall; 15 - reflector; 16 - bolt M 10x35; 17 - handle; 18- top door; 19 - bolt M 10x20; twenty -
wall left; 21 - turbulator; 22 - cover; 23 - gasket; 24 - fitting; 25 - manometric thermometer; 26 - bracket; 27 - branch; 28 - gasket; 29 - frame for thermometer; 30 - gasket; 31 - glass thermometer; 32 - flue pipe; 33 - washer 10; 34- plank; 35 - plate; 36 - branch; 37 - bolt Ml0x25; 38 - gasket; 39 - right wall; 40 - rivet 8x50
KChM-2U Kaunas runs on solid fuel (anthracite, coke, coal), but can be converted to gaseous or diesel fuel.
The heat capacity of the boiler is less than that of KChM-2M Zharok, while the nominal efficiency is higher. Boiler width - 465 mm; height - 63
Technical characteristics of solid fuel boiler KCHM-2
Number of sections, pcs. - 4
Power, W - 16000
Weight, kg - 181
Length, mm - 340
Furnace volume, m3 - 0.03
Grid area, m2 - 0.06
Boiler capacity, l - 27.2
Working vacuum, Pa - 10
KChM-ZDG is equipped with a long-burning furnace and is able to work efficiently without maintenance up to 12 hours. Useful efficiency - up to 79%. The yield of volatile substances is up to 17%. Boiler width - 470 mm; height - 1070 mm.
If desired, the boiler can be converted to gaseous fuel. KChM-ZDG is used to heat houses equipped with a water heating system with a pressure of not more than 0.6 MPa.
Operating characteristics of the solid fuel boiler KChM-2M Zharok-2
Number of sections, pcs. - 3
Power, kW - 16.5
Specific material consumption, kg / kW - 13.8
Weight, kg - 232
Overall dimensions, mm:
Length - 390
- width - 500
- height - 1065
Parameters of solid fuel boiler KCHM-2U "Kaunas"
Number of sections, pcs. - 7
Power, kW - 40.5
Weight, kg - 417
Length, mm - 675
Technical characteristics of the KChM-ZDG boiler
Number of sections, pcs. - 5
Power, kW - 29
Weight, kg - 319
Length, mm - 660
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OPERATION AND REPAIR OF BOILERSProterm Panthera Proterm Skat Proterm Bear Proterm Cheetah Evan
Heating country house
12) has 2-4 sections and a partially cooled grate (from alternately cooled and uncooled elements).
KChM-1 (rice. 13) differs from KChMM-2 only in the number of cast-iron sections, which it has more.
KChM-2 (rice. 14) has 2-8 sections (with a furnace opening in the front section) and gas ducts with flue gas flow extensions, which significantly increase the efficiency of the boiler. Extensions consist of cast iron inserts
Table 6. Technical characteristics of the solid fuel boiler KCHMM-2
|
Number of sections PC. |
|||
|
Power, W |
4 |
5 |
v |
|
Overall dimensions, mm: |
|||
|
length |
590 |
670 |
750 |
|
width |
450 |
450 |
450 |
|
height |
680 |
bao |
680 |
|
Wheel area |
0.04V |
0.064 |
0,08 |
|
grids, m g |
|||
|
boiler capacity, l |
16,7 |
19,7 |
22,7 |
wok with internal ribs and spacers with holes for the passage of gases.
KChM-2M "Zharok-2" (rice. 15) has a furnace for long-term combustion of solid fuel, which, if desired, can be converted to natural gas. The combustion chamber is equipped with bypass kindling channels, which allow loading fuel to the full volume at a time and increasing the duration of the boiler without additional maintenance. The bypass kindling channels are formed by additional ribs on the vertical pipes of cast iron sections and are not filled with fuel. The closed ash space formed by the ribs of the sections contributes to an increase in the gas density in the boiler, which makes it possible to regulate the air supply during kindling by opening the air collector cover at the required angle.
The KCHM-2M "Zharak-2" boiler is used for heating country houses with a building volume of 300-900 cubic meters, equipped with a heating system with natural or forced circulation of the coolant.
KChM-2U "Kaunas" runs on solid fuel (anthracite, coke, coal), but can be converted to gaseous or diesel fuel. The heat capacity of the boiler is less than that of KChM-2M "Zharok", while the nominal efficiency is higher. Boiler width - 465 mm; height -
Table 7. Technical characteristics of the solid fuel boiler KChM-2
|
Number of sections, pcs. |
|||||||
|
Power, W |
16000 |
21000 |
25000 |
31000 |
37000 |
42000 |
46000 |
|
Weight, kg |
181 |
216 |
248 |
283 |
318 |
353 |
386 |
|
Length, mm |
340 |
425 |
510 |
595 |
680 |
765 |
850 |
|
Furnace volume, m 3 |
0,03 |
0,043 |
0,056 |
0,069 |
0,082 |
0,094 |
0,107 |
|
Grate area |
0,06 |
0,086 |
0,112 |
0,138 |
0,163 |
0,189 |
0,214 |
|
gratings, m 2 |
|||||||
|
Boiler capacity, l |
27,2 |
30,5 |
33,8 |
37,1 |
40,4 |
43,7 |
47,0 |
|
Working vacuum, Pa |
Table C. Duration of operation of the KChM-2M "Zharok-2" boiler
|
Indicator |
Anthracite, hard coal |
Hard coal, brown coal |
|
Duration working cycle, h, at least |
12 |
8 |
|
Yield of volatile substances, %, up to |
17 |
50 |
|
Humidity, %, up to |
13 |
13 |
|
Ash content, %, up to |
20 |
20 |
1062 mm. The boiler is used for heating houses with a building volume of 400-1300 m 3.
KChM-ZDG is equipped with a long-burning furnace and is able to work efficiently without maintenance up to 12 hours.
Modernized boilers KCHM-2U "Kaunas" low-rise buildings and individual apartments with a volume of 400-1300 m 3. It burns coke, sorted anthracite, hard coal and briquetted low-ash solid fuels. After appropriate re-equipment, the boilers can operate on natural gas and liquid light fuel (Table 7).
In terms of specific metal consumption, this boiler is somewhat inferior to the KChM-2M "Zharok-2" boiler, but surpasses it in efficiency.
Boilers KCHM-ZDG(Table 8) refer to boilers of a universal type and can be operated on sorted solid fuel, and with appropriate additional equipment on gaseous. In boiler type KChM-ZDG it is possible to efficiently burn both anthracite and hard coal with the release of volatile substances up to 17% in the unsupervised combustion mode. Working cycle duration - 12 hours, efficiency - 78-79%.
Seven versions of boilers are produced with the number of sections from 3 to 9. They can operate in heating systems with natural and forced circulation of the coolant, water pressure not more than 0.6 MPa (6 kgf / s m 2) and temperature not more than 95 ° C.
|
|
Table 8
Technical characteristics of boilers KChM-ZDG
Heat generator |
Rated power, kW |
Number of sections |
Dimensions, mm |
Weight, kg |
||
All cast iron boilers are designed for water heating up to 90-95 ° C and relatively low pressure (24 kgf / s m 2). The disadvantage of all cast iron boilers is the need to manually maintain a constant thickness of the fuel layer on the grate, which is a certain inconvenience for residents. In addition, cast iron boilers are heavy and laborious to install.
In addition to cast iron, it is also advisable to use steel welded boilers.. Boilers of the KS series are made in the form of a rectangular pedestal with an internal firebox surrounded by a water jacket (Fig. 14). In the lower part of the firebox there are grates unified for the entire type series. The furnace is separated from the convective part by a visor.
convective flue is a structure consisting of three horizontal slots 20 mm high, which are formed by installing two water-carrying channels, made with a slope to remove the resulting steam bubbles. The upper door is used to load fuel and clean the convective flue from soot, and the lower one is for servicing the grate and fuel.
Rice. 14. Hot water boiler KS
1 - ash pan; 2 - grate; 3 - firebox; 4 - water jacket; 5 - visor separating the firebox from the convective part; 6 - convective flue; 7 - water-carrying channels; 8 - manometric thermometer; 9 - boot furnace; 10 - door for maintenance of the grate; 11 - adjusting screw; 12 - butterfly valve
The outer surface of the boilers is covered with thermal insulation - hydrophobized basalt cardboard, lined with steel panels and painted with light-colored enamel.
Table 9
Technical characteristics of boilers KS-T
| Indicator | KS-T-11.2 | KS-T-13.7 | KS-T-16.8 | KS-T-23.7 |
| Heat output, kW | 11,2 | 13,7 | 16,8 | 23,7 |
| Efficiency on solid fuel, % | 75 | 75 | 75 | 75 |
| Heating surface, m 2 | 1,12 | 1,38 | 1,68 | 2,37 |
| Heated water parameters: | ||||
| temperature, ° С | 95 | 95 | 95 | 95 |
| absolute pressure, kgf / m 2 | 3 | 3 | 3 | 3 |
| 30 | 30 | 30 | 100 | |
| Vacuum in the boiler furnace, Pa | 15 | 15 | 15 | 30 |
| External surface temperature, ° С | 70 | 70 | 70 | 70 |
| Weight, kg | 100 | 130 | 175 | 225 |
| Duration of work on solid fuel without maintenance, not less |
6 | 6 | 6 | 6 |
Structures of steel hot water boilers are issued in different executions: for work on solid fuel (KS-T); on gas (KS-G); on liquid fuel (KS-Zh); and combined for operation both on solid fuel and on gas (KS-T-G).
Technical characteristics of boilers of the KS series are given in Table. 9-11 .
Table 10
Technical characteristics of boilers KS-Zh, KS-G
| Indicator | Brand of boilers when working on fuel | |||||
| liquid | gaseous | |||||
| KS-Zh-8.1 | KS-Zh-13.9 | KS-Zh-18.5 | KS-G-11.3 | KS-G-22.7 | KS-G-34.0 | |
| Heat output, kW | 8,1 | 13,9 | 18,5 | 11,3 | 22,7 | 34,0 |
| Efficiency,% | 80 | 80 | 80 | 86 | 86 | 86 |
| Absolute water pressure, kgf / m 2 | 3,0 | 3,0 | 3,0 | 3,0 | 3,0 | 3,0 |
| Water temperature, ° С | 95 | 95 | 95 | 95 | 95 | 95 |
| Vacuum, Pa | 15 | 15 | 15 | 25 | 25 | 25 |
| Hydraulic resistance, Pa | 30 | 30 | 30 | 30 | 30 | 30 |
| Weight, kg | 90 | 130 | 170 | 85 | 100 | 120 |
Table 11
Technical characteristics of boilers KS-T-G
| Indicator | KS-T-G-10 | KS-T-G-12.5 | KS-T-G-16 | KS-T-G-20 |
| Rated thermal power, kW | 10 | 12,5 | 16 | 20 |
| Overall dimensions (on the casing), mm | ||||
| width | 430 | 430 | 430 | 430 |
| height | 875 | 875 | 920 | 920 |
| depth | 315 | 350 | 410 | 510 |
| Thermal stress of the combustion mirror, kW / m 2 | 210 | 225 | 225 | 210 |
| Specific volume of fuel loading, dm 3 / kW | 2,5 | 2,3 | 2,6 | 2,7 |
| Weight, kg | 110 | 117 | 135 | 155 |
| Efficiency, % not less than: | ||||
| solid fuel | 77 | 77 | 75 | 75 |
| on natural gas | 81 | 81 | 80 | 80 |
Rice. 15. Firebox with burner for ignition of solid fuel
1 - gas burner; 2 - pad on the gas burner and grate; 3 - grate; 4 - hole for loading fuel; 5 - walls of the firebox; 6 - crane gas burner; 7 - gas supply; 8 - tap for tube; 9 - flexible hose; 10 - blower hole; 11 - tube for ignition of the burner
When burning solid fuel in boilers, especially hard coals and anthracites, there are difficulties with their ignition, since they have a high ignition temperature. If the house has a bottled (liquefied) gas burner, then ignition can be facilitated using a special kindling device (Fig. 15). In this case, a household gas burner is inserted into the middle of the grate, with the help of which the layer is ignited. After the fuel has warmed up, the burner is turned off.
Wood remains the most common type of fuel in rural areas fast "burning" low-calorie fuel. Therefore, it is expedient to burn them in "mine" furnaces with a high layer, in which the fuel burns for a long time.
|
|
On fig. 16 shows the construction of a welded steel firewood boiler. Single-pass boiler with top flue outlet. Air is supplied through the grate (primary) and above the layer of firewood (secondary). The supply of secondary air is necessary due to the fact that when heated, firewood thermally decomposes with the release of combustible volatile gases. The primary air is used to burn the solid part of the fuel remaining on the grate, and the secondary air is used to burn the volatiles in the above-layer space. A feature of the boiler is the possibility of using it not only for heating, but also for hot water supply. To do this, a cylindrical water-to-water heat exchanger is placed in the upper part of the water tank of the boiler, inside which cold water is supplied to be heated for hot water supply, and with outer side the heat exchanger is washed hot water heating system (Table 12).
Most of the manufactured boilers and devices are designed for one function of heat supply - heating. However, in Lately there has been a trend towards the production of combined, or, as they are also called, two-functional heat generators, the design of which allows covering two types of heat loads: heating and hot water supply.
Rice. 16. Sheet steel boiler with wood fire
a - side view; b - front view; c - cross section; 1 - blower door; 2 - cleaning door; 3 - furnace door; 4 - combustion regulator; 5 - water heater; 6 - smoke pipe; 7 - grate; 8 - cleaning with a sand seal; 9 - throttle (opening during kindling and closing during steady combustion); 10 - tubular electric heater
Table 12
Characteristics of a steel boiler with a wood-burning mine furnace
Table 13
Technical data of the boiler KS-T-SV-16
Rated power of the heating circuit, kW (kcal/h) when burning: |
|
Time of continuous operation (at rated power and single load of fuel), h: |
|
on firewood |
|
Instantaneous water heater power, kW |
18 (400 l/h when heating water from 5 |
Operating pressure in the heating circuit, m water column (kgf / s m 2) |
|
Operating pressure in the instantaneous water heater circuit, m water column (kgf / s m 2) |
|
Service life, years |
at least 25 |
Weight, kg, no more |
Automated hot water boiler KS-T-SV-16 designed for heating a residential building with an area of up to 80100 m 2 and hot water supply. The use of thin sheet stainless steel and the special design of the flow heater reduces the weight and dimensions of the boiler and significantly increases its service life. Automatic regulator, tilting grate, big sizes door and ash drawer facilitate boiler maintenance. The regulator can be used in the manual temperature sensor mode, while the outdoor temperature sensor is installed in the heated room (Table 13).
Developed smoke cavity, preheating and air supply on two levels, airflow limitation by automatic regulator
The industry produces special water heaters, the heat exchange surfaces of which are made of steel pipes and sections. The devices differ from cast iron and steel boilers in a more aesthetic design. Apparatus ATV-17.5 (model 930) (Table 14) is the basic model in this series (Fig. 17).
Rice. 17. Two-function solid fuel hot water apparatus ATV-17.5
1 - ash pan; 2 - grate; 3 - furnace door; 4 - firebox; 5 - hot water heat exchanger; 6 - heating heat exchanger; 7 - body; 8 - safety valve; 9 - tuyeres for supplying secondary air; 10 - ash pan door
The apparatus is two vertical cylindrical tanks placed one inside the other. The inner tank is for heating, the outer tank is for hot water supply.
The choice of the type of heat source depends on the type of fuel, its nominal heat output, which should be more than the calculated heat loss of the house by 15-20% of the functional purpose.
Enclosing structures of the most modern low-rise buildings with high thermal resistance have a very low heat-absorbing capacity, as a result of which they are characterized by low heat resistance, and the thermal regime in them is subject to fluctuations under the influence of variable meteorological factors and unstable heat supply. The noted feature predetermines the feasibility of using apartment heat generators with long-term and protracted burning furnaces or using a heating system with a large thermal accumulation.
For decentralized heat supply, the most promising are dual-functional heat generators that simultaneously provide heating and hot water supply with long-burning furnaces when operating on solid fuel.
When using solid fuel for apartment heat generators, it is advisable to use sorted coal, coal briquettes, given that most boilers and devices are not suitable for burning low-grade fuel.
The upper limit of the size of coal fractions in order to avoid multiple combustion should not exceed 50 mm, and the lower limit, due to limited draft and the absence of forced blast, should not exceed 13 mm.
As a liquid fuel, domestic stove fuel (TPB) or lighting kerosene can be used.
Currently, a wide range of residential heat generators operating on solid, gaseous and liquid fuels is presented on the market. Most of them have a water circuit in their design and are intended for use in a water heating system.
With considering specific gravity solid fuel in the fuel balance of the village (over 80%) the greatest interest for the consumer are solid fuel apartment boilers.
The removal of gases from apartment heat generators is carried out through a chimney 5-7m high. The draft created by such a pipe is small, and so that the smoke from the furnace does not knock out into the room, the gas resistance of heat generators should be minimal.
Apartment heat generators should also have the lowest hydraulic resistance, since the total circulation pressure in the system is very small. To increase this pressure, it is advisable to place the heat generator low, but most often such a solution in a one-story building is often unacceptable. At regular accommodation the heat generator on the floor in order to reduce the heating center and increase the hydraulic pressure, it is desirable that the heat generator be of a minimum height, and the heating surfaces should be as low as possible.
Fuel costs account for the bulk of operating costs, so the efficiency of the boiler must be sufficiently high.
The most common are cast iron or steel hot water boilers used alone or in conjunction with household stoves for cooking food. Cast iron boilers have great advantages - they are durable and cheap in mass production. In addition, they are recruited from separate sections, so by changing the number of sections, you can choose any performance. Repair of boilers usually comes down to replacing a burned-out section with a new one. The service life of cast iron boilers is about 20 years, while the remaining 10 - 15 years. Service life from overhaul before repair at least 2000 hours, other designs - at least 8000 hours.
It should be noted that all small-sized boilers have small convective heat exchange surfaces and, as a result, a high temperature of the exhaust gases (250-400 ° C), which causes a decrease in their efficiency. If the boiler is connected to a chimney through a heating shield, the flue gas temperature can be significantly reduced and efficiency increased. When the boiler is kindled, when the draft deteriorates, the forward stroke damper is opened and the gases are directed into the chimney.
They also do it when the heating season starts. When the draft is established, the forward stroke damper closes and the gases are directed to the heating shield.
For the most common fuel - coal, cast-iron boilers of the KChMM, KChMM-2, KChM-1, KChM-2, KChM-3 brands are most often used. Outside, they are sheathed with a casing made of sheet steel. Asbestos sheet thermal insulation is laid between the casing and the cast iron sections.
The KCHMM boiler (Fig. 9) consists of three sections, and all the necessary fittings are placed on the outer sections. The grate is made partially cooled and has a screw device. The gas path of the boiler is equipped with a direct-flow gas duct, which makes it possible to direct gases, in addition to heat exchange surfaces, directly into the chimney during kindling (Table 2).
Rice. 9. Cast iron sectional hot water boiler KCHMM: a - front view; b - incision; c - view from the rear wall
table 2
The boiler KCHMM-2 (Fig. 10) is assembled from the front, rear and intermediate sections, the number of which is from two to four. The grate is formed by alternating cooled and uncooled elements (Table 3).
Rice. 10. Pig-iron sectional hot water boiler KCHMM-2: a - longitudinal section; b - cross section
Table 3
The KChM-1 boiler (Fig. 11) differs from the KChMM-2 boiler mainly in a large number of sections (Table 4).
Rice. 11 Cast iron sectional hot water boiler KChM-1: a - longitudinal section; b - front view
Table 4
In the KChM-2 boiler (Fig. 12), the number of middle sections varies from 2 to 8. The front section has openings for loading fuel, skimming the burning layer and unloading ash. The side walls and top of the boiler are insulated with sheet asbestos and a casing made of sheet steel (Table 5).
Rice. 12. Cast iron sectional hot water boiler KChM-2: 1 - draft chopper; 2 - burner; 3 - return water inlet; 4, 5 - electromagnetic and solenoid valves; 6 - gas supply; 7 - nipple; 8 - electrical wiring; 9 - gas inlet; 10 - hot water inlet; 11 - transformer
Table 5
To improve the thermal properties of the gas ducts are equipped with flue gas flow extensions, consisting of cast-iron inserts with internal ribs and spacers. When installing the inserts, the ribs fall into the intersection slots of the boiler and are fastened with the help of rods. Spacers with holes for the passage of gases are placed in the furnace space between the inserts. Rising upwards, the gases hit the spacer, partially passing through the holes and entering the gaps formed by the inserts and sections of the boiler, thereby improving the heat transfer from the combustion products to the water.
Pig-iron sectional boilers KChM-2M "Zharok-1" and "Zharok-2" (Fig. 13.) Are designed for heating water in heating systems of low-rise buildings and individual residential buildings with a building volume of 300-900m3 ("Zharok-1"), 200 -600m3 ("Zharok-2") (Table 6). They are universal and can operate on sorted solid fuels (anthracite, coke, hard and brown coal and low-ash briquetted fuel), and with appropriate re-equipment, also on gaseous. Boilers of the "Zharok" type can operate in water heating systems with natural and forced circulation at a hydrostatic pressure of up to 0.3 MPa (3 kgf / cm2) and a coolant temperature of up to 95 ° C.
Rice. 13. Hot water boiler type KCHM-2M "Zharok-2": 1 - package of sections; 2 - lattice; 3 - right wall; 4 - handle; 5 - air intake; 6 - ash box; 7 - bottom door; 8 - left wall; 9 - top door; 10 - cover; 11 - branch; 12 - flue pipe
Technical characteristics of the boiler "Zharok-2"
Table 6
The furnaces of the "Zharok" boilers are adapted for long-term and efficient combustion fuel. In the boiler furnace, due to additional ribs on the vertical pipes of the sections, bypass kindling channels not filled with fuel are formed, which make it possible to reduce aerodynamic resistance, make a one-time load of fuel in full, and increase the time of operation of the boiler without maintenance.
The closed ash space formed by the ribs of the sections ensures the gas tightness of the boiler, which is necessary for regulating the supply of primary air.
The supply of primary air to the combustion zone is regulated by opening the air intake cover to the required angle. The duration of the working cycle in the mode of long burning of the boiler:
On anthracite and hard coal with volatile matter up to 17%, ash content up to 20%, humidity up to 13% is at least 12 hours;
On hard and brown coal with volatile matter up to 50%, ash content up to 20%, humidity up to 13% is at least 8 hours.
Boilers of "Zharok" type can be converted to burn natural gas. The transfer of the boiler to work on gas, the installation of safety automation and commissioning is carried out by local production and maintenance offices of the gas economy.
Modernized boilers KChM-2U "Kaunas" are used in water heating systems of low-rise buildings and individual apartments with a volume of 400-1300 m3. It burns coke, sorted anthracite, hard coal and briquetted low-ash solid fuels. After appropriate re-equipment, the boilers can operate on natural gas and liquid light fuel (Table 7).
Technical characteristics of the boiler KCHM-2U "Kaunas"
Table 7
In terms of specific metal consumption, this boiler is somewhat inferior to the KChM-2M "Zharok-2" boiler, but surpasses it in efficiency.
Boilers KChM-3DG (Table 8) belong to boilers of a universal type and can be operated on sorted solid fuel, and with appropriate additional equipment on gaseous fuel. In a KChM-3DG type boiler, both anthracite and hard coal can be efficiently burned with an output of volatile substances up to 17% in the unsupervised combustion mode. Duration of the working cycle - 12 hours, efficiency - 78-79%.
Technical characteristics of boilers KChM-3DG
Table 8
Seven variants of boilers are produced with the number of sections from 3 to 9. They can operate in heating systems with natural and forced circulation of the coolant, water pressure not more than 0.6 MPa (6 kgf / cm2) and temperature not more than 96 C.
All cast iron boilers are designed for water heating up to 90-95 ° C and relatively low pressure (2-4 kgf / cm2). The disadvantage of all cast iron boilers is the need to manually maintain a constant thickness of the fuel layer on the grate, which is a certain inconvenience for residents. In addition, cast-iron boilers are heavy and time-consuming to install.
In addition to cast iron, it is also advisable to use steel welded boilers. Boilers of the KS series are made in the form of a rectangular pedestal with an internal firebox surrounded by a water jacket (Fig. 14).
Rice. 14. Hot water boiler KS: 1 - ash pan; 2 - grate; 3 - firebox; 4 - water jacket; 5 - visor separating the firebox from the convective part; 6 - convective flue; 7 - water-carrying channels; 8 - manometric thermometer; 9 - boot furnace; 10 - door for maintenance of the grate; 11 - adjusting screw; 12 - butterfly valve
In the lower part of the firebox there are grates unified for the entire type series. The furnace is separated from the convective part by a visor.
The convective flue is a structure consisting of three horizontal slots 20 mm high, which are formed by installing two water-carrying channels, made with a slope to remove the resulting steam bubbles. The upper door is used to load fuel and clean the convective flue from soot, and the lower one is for servicing the grate and fuel. The outer surface of the boilers is covered with thermal insulation - hydrophobized basalt cardboard, lined with steel panels and painted with light-colored enamel.
Designs of steel hot water boilers are available in different versions: for solid fuel operation (KS-T); on gas (KS-G); on liquid fuel (KS-Zh); and combined for operation both on solid fuel and on gas (KS-TG).
Technical characteristics of boilers of the KS series are given in Table. 9-11.
Technical characteristics of boilers KS-T
Table 9
Technical characteristics of boilers KS-Zh, KS-G
Table 10
Technical characteristics of boilers KS-TG
Table 11
When burning solid fuels in boilers, especially hard coals and anthracites, it is difficult to ignite them, since they have a high ignition temperature. If the house has a bottled (liquefied) gas burner, then ignition can be facilitated using a special kindling device (Fig. 15).
Rice. 15. Furnace with burner for ignition of solid fuel: 1 - gas burner; 2 - pad on the gas burner and grate; 3 - grate; 4 - hole for loading fuel; 5 - walls of the firebox; 6 - gas burner tap; 7 - gas supply; 8 - tap for tube; 9 - flexible hose; 10 - blower hole; 11 - tube for ignition of the burner
In this case, a household gas burner is inserted into the middle of the grate, with the help of which the layer is ignited. After the fuel has warmed up, the burner is turned off.
Wood remains the most common type of fuel in rural areas- Fast-burning low-calorie fuel. Therefore, it is expedient to burn them in "mine" furnaces with a high layer, in which the fuel burns for a long time.
On fig. 16 a, b shows the design of a steel welded boiler for burning wood. Single-pass boiler with top discharge of combustion products.
Fig. 16 A boiler made of sheet steel with a wood-burning firebox: a - side view; b - front view; c - cross section; 1 - blower door; 2 - cleaning the door; 3 - furnace door; 4 - combustion regulator; 5 - water heater; 6 - smoke pipe; 7 - grate; 8 - cleaning with a sand seal; 9 - throttle (opening during kindling and closing during steady combustion); 10 - tubular electric heater
Air is supplied through the grate (primary) and above the layer of firewood (secondary). The supply of secondary air is necessary due to the fact that when heated, firewood thermally decomposes with the release of combustible volatile gases. The primary air is used to burn the solid part of the fuel remaining on the grate, and the secondary air is used to burn the volatiles in the above-layer space. A feature of the boiler is the possibility of using it not only for heating, but also for hot water supply. To do this, a cylindrical water-to-water heat exchanger is placed in the upper part of the water tank of the boiler, inside which cold water is supplied to be heated for hot water supply, and from the outside the heat exchanger is washed with hot water from the heating system (Table 12).
Table 12
Most of the manufactured boilers and devices are designed for one function of heat supply - heating. However, recently there has been a trend towards the production of combined, or, as they are also called, dual-functional heat generators, the design of which allows covering two types of heat loads: heating and hot water supply.
The automated hot water boiler KS-TSV-16 is designed for heating a residential building with an area of up to 80-100 m2 and hot water supply. The use of thin sheet stainless steel and the special design of the flow heater reduces the weight and dimensions of the boiler and significantly increases its service life. An automatic regulator, a tilting grate, large doors and an ash drawer facilitate boiler maintenance. The controller can be used in the manual temperature setting mode, while the outdoor temperature sensor is installed in the heated room (Table 13).
Table 13
Developed smoke cavity, pre-heating and air supply in two levels, limitation of air inflow by an automatic regulator and high-quality thermal insulation of the furnace and water-heating assembly reduces heat losses and increases the time of continuous (without maintenance) operation of the boiler up to 12 hours.
High-quality thermal insulation and a large volume of the water-heating tank allow the boiler to be used in the heat accumulator mode during the non-heating season, providing the current needs for hot water with a short firebox once a day.
The industry produces special water heaters, the heat exchange surfaces of which are made of steel pipes and sections. The devices differ from cast iron and steel boilers in a more aesthetic design. The ATV-17.5 device (model 930) is the basic model in this series (Fig. 17).
Rice. 17. Two-function solid fuel hot water apparatus ATV-17.5: 1-ash pan; 2 - grate; 3 - furnace door; 4 - firebox; 5-heat exchanger for hot water supply; 6 - heating heat exchanger; 7 - body; 8 - safety valve; 9 - tuyeres for supplying secondary air; 10 - ash pan door
Table 14
The apparatus consists of two vertical cylindrical tanks placed one inside the other. The inner tank is for heating, the outer tank is for hot water supply.
Distinctive feature device is the redistribution of heat between heating and hot water systems. Depending on the increase in one of the functional loads, the coolant can be heated to higher temperatures due to the heat transfer by the coolant of another system. The redistribution of heat is carried out through four bracket-shaped pipes and an adjacent cylindrical surface, washed by the heat carriers of both systems.
The water of the heating system is heated to the design parameters due to the transfer of heat through the surfaces and from the fire tube located inside the heating heat exchanger, through which the flue gases from the furnace pass.
The design of the combustion device allows you to burn solid fuel in a thick layer, providing a one-time load of about 30 kg of fuel for 6-8 hours of continuous operation.
The primary combustion air enters under the grate, through the louvered openings of the ash pan door. Secondary air for post-combustion of volatile substances is supplied to the above-bed space through tuyeres with an adjustable cross section.
On the basis of the ATV-17.5 apparatus, a two-functional heat generator ATV-23.2 (model 3107) (Fig. 18) was created, operating in the long-burning mode. The device has a loading hopper and an inclined grate. The fuel is fed through the hopper, from which, under the action of its own weight, the fuel enters the inclined part of the grate. The thickness of the fuel layer is regulated by a damper.
The volume of the bunker is designed for a reserve of up to 45 kg of coal, which allows the device to be operated without additional loading during the day (Table 15).
Rice. 18. Two-function solid fuel hot water apparatus ATV-23.2 (model 3107): 1-decorative casing; 2 - flue; 3, 4 - manometric thermometers: 5 - heating heat exchanger; 6- thermal insulation material 7-cast iron reflector; 8 - loading door; 9 - tuyeres for supplying secondary air; 10 - kindling door; 11 - ash pan door; 12 - ash pan; 13 - grate; 14 - firebox; 15-flap regulating fuel supply; 16 - loading hopper, 17 - stopper; 18 - shutter; 19 - hot water heat exchanger 20 - flue pipe
Table 15
The two-functional heating apparatus with hot water supply on wood and peat briquettes ATV-23.2 (model 3131) is designed for centralized heating and hot water supply of individual residential buildings with an area of 100-150m2.
The design of the apparatus is made in the form of a rectangular pedestal. The devices have a firewood bunker, a firebox with vertical and horizontal grates, cast-iron screens, a water heating circuit, a hot water tank, gas ducts (Fig. 19).
Rice. 19. Two-functional solid fuel hot water apparatus ATV-23.2 (model 3131): 1 - flue; 2 - heating heat exchanger; 3 - fuel bunker; 4 - hanging vertical screens; 5 - suspended vertical grate; 6 - loading door; 7 - grate; 8 - ash pan; 9 - device for supplying secondary air; 10 - hot water heat exchanger
Technical characteristics of the apparatus ATV-23.2 (model 3131)
Table 16
A distinctive feature of the device is the presence of a furnace that ensures the operation of the device for at least 8 hours from one load, and the use cast iron screens for better afterburning of volatile substances.
The fuel on the grate burns with the orientation of the torch towards the suspended vertical grate. For more complete combustion, secondary air is supplied to the combustion zone through the device. Flue gases rise up through the gas ducts, descend through the gap in the upper part of the furnace into the lower part of the flue and enter the fire tube, heating the hanging vertical screens and the coolant in the heat exchange tank along the way. Heated suspended vertical screens accumulate heat and contribute to further afterburning of volatile substances.
Due to the presence of adjacent walls of heat exchangers for heating and hot water supply, heat is redistributed depending on heat consumption.
The industry produces a wide range of gas heating household appliances with a water circuit in sizes from 11.6 to 29 kW of the AOGV type (Table 17), AGV.
Table 17
Devices of this type consist of the following parts: a vertical cylindrical tank, a casing, a gas burner with an igniter, and a gas exhaust device (Fig. 20).
A heat exchange pipe with an extension is located in the center of the tank. The space between the tank and the shell is filled with slag or glass wool insulation. A draft breaker is located above the outlet of the flame tube. An injection burner is located at the bottom of the apparatus. low pressure, in which the igniter is attached to the bracket. The igniter has two flames: the main burner is ignited from one, the thermocouple junction is heated from the second.
The burner mixer is a profiled pipe bent at an angle of 90°. The mixer diffuser has a cast-iron nozzle. Fire holes in the nozzle are drilled in special tides located in one row, which improves the conditions for supplying secondary air to the torches. Since the burner operates with an excess air ratio a
Water heaters are equipped automatic systems security and regulation. The water heater safety automatics consists of a solenoid valve and a thermocouple connected to it by wires. During normal operation of the device, the igniter heats the thermocouple junction, an EMF develops in the circuit and an electric current flows through the solenoid valve winding, which keeps the valve open. In this case, the gas enters the main burner. If the igniter goes out, the thermocouple junction will cool down and the solenoid valve will close the gas access to the main burner and igniter. Re-ignition of the igniter should be carried out manually, but not earlier than after 2 minutes. The water heater is put into operation only after filling it with water. To do this, just open any of the hot water taps and make sure that water flows out of it under pressure. Then open the tap on the gas duct in front of the apparatus, bring a lit match to the igniter and open its tap. 1-2 minutes after ignition of the igniter, it is necessary to pull down the button of the electromagnet to the full, while the button should remain in the lower position. After making sure that the igniter is lit, open the tap of the main burner and light it. If the burner does not light up, and the igniter goes out, then re-ignition can only be done after the furnace has been ventilated for 2-3 minutes. Having started the water heater, it is necessary to close the door and check the presence of vacuum in the chimney using a lit match. In the absence of vacuum in the chimney, it is strictly forbidden to use the water heater. After heating the water to the required temperature, the thermostat stops the gas supply to the main burner. When the water temperature in the heater drops by 5-10° (as a result of hot water withdrawal or heat loss during heating), the thermostat resumes gas supply to the main burner. Adjustment of the maximum water temperature is made by rotating the lower right nut of the unit automatically. When the temperature drops, the nut must be turned down, when the temperature rises, it must be turned up.
To turn off the water heater, it is necessary to close the igniter valve and the main burner valve, as well as the valve on the gas pipeline in front of the appliance.
Water heaters are serviced by persons who have read the instructions and the basic safety rules for operating gas appliances.
Capacitive water heaters of the AGV, AOGV type with the removal of combustion products into the chimney can be installed in bathrooms and kitchens. The main characteristics of AGV water heaters are given below.
Table 18
The volume of the bathroom when using water heaters of the AGV type must be at least 6 m3. An increase in the volume of the kitchen beyond that provided is not required.
On fig. 21 shows the installation of the AVG-120 equipment. Water heaters are connected to the chimney with roofing steel pipes 0.8-1 mm thick, and the diameter of the connecting pipes must be at least 80 mm for AGV-50mm and AGV-80mm and at least 100mm for AGV-120. The total length of the horizontal sections of the connecting pipes should be no more than 6 m (Table 18).
Cast iron sectional boilers of the KChM series can also be used for burning gaseous fuels. For this, the boilers are equipped with specially equipped low-pressure injection burners. Burner nozzles have a rectangular shape in the form of a frame (with a jumper in the middle). The gas-air mixture from the burner mixer is fed to the center of the jumper, and then from both sides to the outlets located along the perimeter of the frame. The two-row arrangement of the firing holes allows to reduce its size, but worsens the conditions for supplying secondary air. This slightly increases the length of the torch compared to burners with a single row of holes.
The nominal pressure in front of burners operating on natural gas is 1300 Pa, on liquefied gas - 3000 Pa.
The burners are installed at the level of the grate, which is removed when working on gas. Instead of a furnace door, a front plate is installed. A supply gas pipeline, a burner and automation devices are attached to the front plate. In boilers with a different number of sections, burners of a certain heat output are installed.
The boilers are equipped with two-position automatic water temperature control. The temperature regulator installed at the outlet of hot water from the boiler acts on the solenoid valve through which gas is supplied to the main burner. The operation of the thermostat is based on the use of metals with different coefficients of linear expansion. The outer brass tube has a linear expansion coefficient greater than the inner invar rod. When the water is heated above the set temperature, the thermostat operates and opens the solenoid valve circuit. The solenoid valve closes and stops gas from reaching the burners. Gas continues to flow to the igniter through the solenoid valve. When the water temperature drops, the length of the brass tube decreases, the spring returns the levers to their original position and closes the electrical contact in the solenoid valve circuit. The solenoid valve opens and supplies gas to the burners. The gas in the burner is ignited by the igniter. Temperature controller setting limits from 45 to 85 ° С.
The solenoid valve is the actuating device of automatic control. The solenoid coil is connected to the source alternating current voltage 12V. The electromagnet pulls the core in, while lifting the valve and allowing gas to pass to the burner. Gas must be supplied to the solenoid valve from the side of the valve, thereby ensuring a high density of valve closure.
Safety automation consists of a thermocouple, pilot burner and solenoid valve. Chromel-Copel thermocouple is a source of electromotive force (EMF) in the power supply system of the solenoid valve. The thermocouple junction is heated by an igniter torch and an electric current flows in the circuit and winding of the solenoid valve connected to the thermocouple under the influence of the thermocouple junction EMF. The disc anchor of the valve is connected to a stem, to the lower end of which a poppet valve is attached. In the non-working position, the poppet valve is pressed by a spring against the upper seat and shuts off gas access to the main and pilot burners. When starting the solenoid valve into operation (during the ignition of the boiler), it is necessary to press the button, which is connected to the poppet valve through the stem. This opens the access of gas to the pilot burner through the hole in the valve body. When the thermocouple is heated, under the action of the EMF, the armature is pressed against the electromagnet, and the valve opens the gas to the main burners. When the thermocouple cools, the valve closes under the action of a spring and stops the gas supply. Automatic shutdown of the gas when the pilot burner goes out occurs after no more than 25 seconds.
Installation of boilers of the KCHM type is allowed only in non-residential premises with a volume of at least 7.5 m3 with a ventilation duct. When installing the boiler in the kitchen, its volume must be 6 m3 more than required for installation gas stoves. The distance between the protruding parts of the boiler burner and the opposite wall is at least 1 m, and the distance between the side and rear walls of the boiler and the room wall is at least 0.4 m.
The boiler is connected to the chimney using pipes made of roofing sheet (thickness 0.8-1 mm), the diameter of the connecting pipes is not less than the diameter of the branch pipe.
The installation diagram of the KMCH type boiler in the room and its connection to the chimney is shown in fig. 22.
The total length of the horizontal sections of the connecting pipes for the removal of combustion products must be no more than 6 m. The length of the vertical section of the connecting pipe (from the boiler nozzle to the axis of the horizontal section) must be at least 0.5 m. The slope of the connecting pipes towards the boiler is at least 0, 01. The links of the connecting pipes must be tightly pushed one into the other (in the direction of movement of the combustion products) at a distance of at least 0.5 pipe diameters. Laying of connecting pipes through residential premises is not allowed. Connecting pipes laid in unheated premises are thermally insulated. chimney must be at least 3 Pa.
Before starting (igniting) the boiler, make sure that the system is filled with water (check by the appearance of it from the signal pipe at the sink). Then you need to turn on the transformer in the mains and open the tap on the gas pipeline at the entrance to the boiler. Through the peephole of the boiler, it is necessary to bring a burning match to the igniter and at the same time press the button of the solenoid valve to the full. After 1-2 minutes, release the valve button and make sure that the igniter is on. If the igniter goes out, it is necessary to re-ignite. Then smoothly open the gas valve in front of the burner and, making sure that the gas burns at all burner openings, regulate its flame; when signs of flame separation appear with the air regulator, the primary air supply is reduced, and in the presence of a sooty flame, its supply is increased by rotating the regulator.
After starting the boiler, check the presence of vacuum in the chimney using a burning match. In the absence of vacuum, as well as when the flame is knocked out of the furnace, it is strictly forbidden to use the boiler.
When the water in the boiler reaches the set temperature, the burner automatically turns off, but the igniter continues to burn. When the water cools down to 5-6°C, the burner turns on automatically. If it is necessary to increase the water temperature, the arrow of the thermostat is moved towards the position 1Hot1, if lowered - towards 1Hol1. The temperature of the water heated in the boiler is controlled by a thermometer.
To stop the boiler, close the gas valves in front of the burner and at the inlet to the boiler, as well as de-energize the transformer. Maintenance of the boiler must be carried out by trained and certified personnel in full accordance with the instructions. In areas where liquid household heating fuel (TPB) or kerosene is widely used, autonomous heating systems using factory-made apparatus and boilers operating on this type of fuel have become widespread. The industry produces heating devices of the AOZHV type (Fig. 23).
Rice. 23. heating apparatus type AOGV: 1 - gate; 2 - hinged cover; 3 - heat exchanger cover; 4 - fuel tank; 5 - heat exchanger; 6 - screen; 7 - flame tube; 8 - hatch; 9 - front wall; 10 - dispenser; 11 - burner casing; 12 - pallet; 13 - burner; 14 - air regulator; 15 - smoke box
AOZhV devices are made in the form of a floor-mounted metal cabinet with hinged lids and a front wall, which provides free access to the controls. It consists of a burner 13, a flame tube 7, a heat exchanger 5, a fuel tank 4, a cover 2 and a dispenser 10. A cylindrical flame tube is installed above the burner located in the lower part of the apparatus, which serves as a combustion chamber. From above it is closed with a heat-insulating cover with a screen. The chamber is attached to the heat exchanger of the apparatus using four easily removable locks. The heat exchanger is made of two concentrically arranged cylinders, the annular space between which is filled with water. There are two fittings in the lower and upper parts of the heat exchanger (respectively, for supplying cold and discharging hot water). Outside, the body of the burner is closed with a heat-insulating casing, the installation of which reduces heat loss to the surrounding space and at the same time creates a directed movement of air into the combustion zone. On the side surface of the casing there is a slide-type air regulator. As the vacuum in the apparatus increases, the gate section is blocked by a damper, due to which the excess air coefficient changes by a small amount. The amount of fuel supplied to the burner, and, consequently, its thermal load is changed with the help of a dispenser, which ensures that a given amount of fuel is supplied to the burner or stops it if the fuel level in the dispenser housing rises above the control one. The dispenser is designed in such a way that with an increase in the fuel level, the float in its body emerges and through the lever system presses on the shut-off needle of the inlet valve, which shuts off the fuel supply to the dispenser. A fuel tank with a capacity of 16 liters is mounted in the front of the apparatus, equipped with a float-type level indicator. The reserve of fuel in the tank is sufficient for continuous operation of the device for 15 hours at normal load. The temperature in the tank must not exceed the flash point, so the tank is separated from the heat exchanger by a screen to avoid overheating. On the rear wall of the water jacket of the heat exchanger there is a smoke box, in the upper part of which a gate is installed, which serves to change the direction of movement of the fuel combustion products. At the bottom of the machine is a drip tray to collect spilled fuel. The device is equipped with an evaporative burner with natural air suction. Combustion products, leaving the flame tube, transfer heat to the water in the heat exchanger, after which they are thrown into the chimney, and the heated water enters the building's water heating system. During the ignition period of the apparatus, when the vacuum in it is insignificant, the smoke box damper (to reduce the hydraulic resistance of the smoke path) is set to the “Open” position, and the combustion products enter the chimney directly through the smoke box. After the device enters the mode (heating water to a temperature of 85-90 ° C), the gate is set to the “Closed” position. In this case, the combustion products pass through the annular gap between the flame tube and the water jacket of the heat exchanger.
The device has a satisfactory quality of fuel combustion. The content of carbon monoxide in the products of fuel combustion is 0.005-0.02%, which does not exceed the maximum allowable standards for devices of this type. The main technical characteristics of AOZHV type devices are given in Table. nineteen.
Table 19
Installation of heat generators
The placement of heating boilers (appliances), as a rule, should be provided in special rooms (furnace rooms) with a chimney and a ventilation duct.natural ventilation must provide three air exchanges for one hour, not counting the air necessary for combustion. The room must have electric lighting.
Placing a heating boiler (apparatus) on solid fuel in the kitchen is not recommended for sanitary and hygienic indicators. Installing a solid fuel boiler (apparatus) in the basement of a house allows you to increase the circulation pressure, thereby reducing pipe diameters, and improving the sanitary and hygienic condition inside the house. When installing a heat source in a room built of combustible materials, the distance from the boiler to walls, ceilings and partitions must be at least 0.5 m. The distance can be reduced to 0.25 m, provided that combustible structures are sheathed with roofing steel on asbestos cardboard with a thickness of 8 mm.
When placing a heat generator near a fireproof or slow-burning wall, the distance between it and the wall must be at least 5 cm, the same distance can be provided if the combustible structures of the house are lined with brick on edge to a height of 1.5 m.
To protect the floor and walls from fire when installing heat generators for solid and liquid fuels, a metal sheet 0.7x0.5 m in size from roofing steel on asbestos-cement cardboard 8 mm thick should be provided on a combustible or hardly combustible floor under the furnace door. Before the boiler (apparatus, furnace) there must be a passage of at least 1.25 m - when working on solid and liquid fuels, and at least 1m - when working on gas.
For heating individual apartments and individual houses, boilers KChM-2M, Zharok-2 (Fig. 1-9-28) KChM-2UE (Table 1.9.3) and others have proven themselves well.
Boilers of the KChM-2M "Zharok-2" type are designed for space heating with a volume of 300-950 m3. For heating the maximum volume, nine-section boilers are used. Boilers of the KChM-2U and KChM-2UE types can be used in water heating systems for rooms with a volume of 400-1300 m3.
The Kirov iron foundry produces boilers of the KChM-ZM, KChM-ZA, KChM-5 types. Their technical specifications given in tables 1.9.4 and 1.9.5.
The design of the boilers should provide the possibility of burning both household stove fuel (boughs, firewood) and industrial fuel (coal, coke, briquettes) and, after re-equipment, gas and liquid combustible materials. The temperature in the room should not drop sharply for the period when the fuel addition is stopped (at night), i.e., the duration of the working cycle in the long-term burning mode should be within 8-12 hours. For KChM-2M boilers, the burning time on anthracite and coal with ash content up to 20% and moisture content 13% is at least 12 hours with the release of volatile components up to 17%. If the yield of volatile components in hard and brown coal increases to 50%, then the duration of the working cycle in the long-term burning mode is reduced to 8 hours, which barely covers the night break in work.
There must be a draft in the exhaust pipe that does not allow smoke to enter the room. For boilers with a heat output of up to 25 kW, a thrust of 1.7 Pa and above is required. In practice, this means that the cross section of the chimney must be 130x250 mm, it must be vertical, smooth, free of cracks and narrowing, and lie in the internal main wall. A separate brick pipe, installed in compliance with the rules, is also acceptable. fire safety. The height of the pipe from the boiler grates must be at least 5 and protrude above the roof ridge by at least 0.5 m, if there are no tall trees or houses nearby that create wind backwater zones. For boilers with a power of 25 to 50 kW, the chimney section increases to 250x250 mm.
The channels in the boiler for the heat carrier must have a minimum hydraulic resistance, which guarantees the use of the boiler in heating systems with natural circulation. It is forbidden to install shut-off and control valves on the return and supply lines. This does not apply to auxiliary lines, in particular, for replenishing and draining the coolant from the heating system.
As the operation progresses, the boiler channels, system pipelines, heaters, and expansion tank are periodically cleaned and washed. For the summer, the system is left with water, which dramatically reduces the corrosion of internal surfaces.
Standard size of the KCHM-2M boiler to ensure minimum flow fuel at high efficiency is determined according to the aggregated data in Table. 1.9.6, which also shows the annual consumption of sorted anthracite, depending on the volume of the heated room for middle lane Russia.
With the lowest location of the heating center, the dimensions of the boiler should be minimal.
Boilers are assembled from separate sections (Fig. 1-9-28, 1-9-29) in the same way as cast-iron radiators. However, the boiler sections are heated so that there is a cavity for the firebox on the side facing the floor. Connect the sections with nipples screwed into special threaded holes. Each of the nipples has an internal hole through which water circulates between the sections. The outer surfaces of the sections have ribs. After joining the sections, the ribs form channels through which the combustion products pass: gases, flames.
Sections are divided into frontal, middle and rear. Doors, ash drawers, an air collector are placed in the frontal one, outlets to the main riser and return line of the heating system, a gas duct, and an air duct are connected to the back. The value of the thermal power of the boiler depends on the total number of sections, on their size and is expressed in kW. Ash drawers are inserted into special closed spaces under the firebox, formed by section ribs, which provide the gas tightness necessary to adjust the primary air supply. The latter is carried out by turning the air collector cover at a certain angle.
Pipelines connected to the boiler are laid with a slope of 1:100, which contributes to the release of air and draining of water when the system is emptied.
Boilers are mounted in non-residential premises with a height of at least 2 m and a volume of at least 8.5 m3. Ventilation of the room should provide at least three air exchanges in 1 hour. Natural ventilation functions only at temperatures above +5 ° C outside. Therefore, to excite it in the frosty season, a deflector is fixed on the head of the exhaust pipe.
It is best to lay ventilation ducts in the immediate vicinity of the chimneys. The heating of the ventilation ducts intensifies the exhaust. Channels should not have sharp turns, their radius is not less than 100 mm. At an accessible distance from the floor, the channel must have a gate in order to change the cross section depending on the ambient temperature ventilation duct. In some cases, a ventilator is enough to ventilate the room. They put the boiler on a special foundation or directly on the floor, depending on the quality of the floor. If the floor is wooden, the installation site is lined with bricks laid on edge over the entire area of the boiler base. Bricks can be replaced by a steel sheet laid on felt soaked in clay. The floor in front of the doors is lined with steel sheet on asbestos cardboard. The sheet must extend beyond the dimensions of the boiler by at least 0.5 m, and on its sides by 0.3 m. Instead of a steel sheet, bricks or a layer of crushed stone, enclosed by a frame, are acceptable. The side walls of the boiler are located at a distance of 0.4-0.5 m from brick walls, back wall - 0.17-0.5 m. Flammable walls are lined with asbestos at least 3 mm thick and steel sheet or brickwork. Horizontally, the lining should extend beyond the walls of the boiler by 0.2-0.3 m, vertically - by 0.5 m above the level of the cover.
Fuel is stored no closer than 0.5 m from the boiler. The passage between the front of the boiler and the wall must be at least 1 m, and from the sides - at least 0.4 m. The permissible temperature of the front and rear walls of the boiler is up to 110 ° C, the side walls - up to 90, the floor under the boiler - 40-50 ° WITH. Heating appliances are not installed near the boiler, the heat dissipation of the boiler is sufficient. Boilers come from the manufacturer to the store, usually disassembled. When buying a boiler, you should check its completeness.
At the installation site of the boiler, they are convinced of the integrity of the sealing coating of the joints of the sections along their entire perimeter. Depressurized edges are smeared with any heat-resistant material, such as clay or crushed and soaked asbestos. Assemble the boiler in accordance with the instructions in the passport. An expansion tank of any design is mounted at the highest point of the heating system.
To use natural gas (Fig. 1-9-29), the boiler is additionally equipped with safety automatics with burners purchased in the store. Start-up and connection of this equipment is carried out by the local office of the gas industry. The domestic industry produces boilers of the AGV type, operating only on gas fuel, and recently imported boilers have appeared on the Russian market. gas boilers in particular boilers German company Vaillant.
Having connected the boiler through outlets with gaskets to the main riser and return line, fill the heating system with water. When water flows from the overflow pipe of the expansion tank, filling is stopped. If the heating system is just installed, check the connections. The detected leak is eliminated by draining the water if necessary.
As well as when kindling the stove, paper, wood chips, firewood are placed on the grate of the boiler. Open the lower door or the blower door and the gate. If the boiler has an air duct, then it is raised and fixed in the upper position. Close the damper with a bracket. A thin layer of fine charcoal is poured onto the burning firewood. When it is hot, a larger layer of fine coal or pieces of coarse coal (no more than a fist) are laid on top. Due to the gaps between the pieces, large charcoal burns better than small charcoal. Very fine coal should be moistened with water. Practice proves that the larger the layer of fuel, the higher the efficiency of the boiler. The recommended thickness of the fuel layer is given below: coke, anthracite, coal grade T - 100-200 mm; coal grade G, D and brown peat briquettes - 200-300 mm; firewood - 300-400 mm.
In the last two cases, it is allowed to first put a layer of fuel on the grate and kindle kindling on it. When burning coke, anthracite, T-grade coal (high-calorific fuel with a yield of volatile components up to 17%), the damper of the gas duct branch pipe and the air intake cover are fully opened (see Fig. 1-9-28). When burning another fuel, which has a yield of volatile components up to 50% and a calorie content is reduced, the air collector cover is extended at an angle of up to 15 °, and the damper is covered.
The intensity of fuel combustion is largely affected by thrust. The amount of air supplied can be adjusted by closing the blower door and poking through the fuel. Blue tongues of flame above the coal indicate that the fuel is not combustible, a reddish glow indicates a normal combustion process. All maintenance operations of the boiler should be carried out quickly in order to prevent a mass of air from breaking through the doors. The firing process must not be stopped while the grates are being cleaned. Unlike a furnace, chilled water from the return line circulates in the boiler walls. Therefore, the furnace is loaded onto burnt or burning fuel. After that, the slag is cut through the grooves and corner gaps of the grating with a cutter. At the same time, part of the fresh fuel falls into the ash boxes. He is returned to the furnace. Slag should be removed at least twice a day, until it sets with the grate. If this happens, then the burning fuel is raked to the walls. Acting along the grate with a poker and a cutter, they knock down the slag.
The most dangerous period in operation is the moment of closing the gate, damper or other lock of the hood. It is preferable to close them when the fuel has completely burned out, which guarantees against fumes. You can try to close the gate at the moment when a relatively thin layer of dark red coals remains on the grate, above which there are no bluish flashes.
It is very important that water circulates in the water circuit of the boiler, including the expansion tank. If in expansion tank flow type water will only be at the bottom, the water circulation will be interrupted (see Fig. 1-9-27). An indicator of the cessation of water movement is the cooling of pipes and the appearance of knocks. This can lead to overheating of the boiler sections, causing uneven stresses and cracking. In this case, you will have to purchase a new boiler.
If the thermometer in the main riser shows a water temperature of up to +95 ° C, and no knocks are heard in the system, then the system is supplemented in the usual way. At temperatures above +95 ° C, when knocks are heard - hydraulic shocks from vaporization in the system - open the doors and try to remove some or all of the burning fuel. In another way, the gate, air collector, and air duct damper are closed in order to somewhat reduce combustion. But at the same time, the appearance of waste is possible, so they ventilate the boiler room with all available methods. Adding too much fresh fuel to the furnace will also help lower the temperature. When it drops to +75 °C, you can add water to the system and start heating the boiler again. The temperature of the water will decrease even faster if it is very carefully poured into the return line. cold water, starting with the minimum portions, so as not to create temperature surges in the sections.
The water temperature in the boiler is maintained depending on the ambient temperature (Table 1.9.7).
Unsatisfactory operation of the boiler is possible for many reasons. These include a small section of the chimney. It is believed that for a boiler with a water circuit, it should be in the range of 100-230 cm2. The exact cross section is calculated by the formula:
Two boilers must not be connected to one chimney with a cross section of 130x250 mm.
Weak draft in a chimney of normal section is possible due to a crack in the chimney; due to the fact that a brick fell into the chimney; if the distance from the boiler grates to the mouth of the pipe is less than 5 m; pipe head below the roof ridge; the head of the pipe is higher than the ridge of the roof, but there is a tall house or tree nearby; the connection of the flue pipe to the chimney is leaky; the protective cap or deflector on the chimney head is incorrectly installed; stub open. The operation of the boiler may be unsatisfactory if the pipelines have a slope in the opposite direction to the desired one, if the radiators are air-filled, etc.
During the operation of the boiler, various salts contained in fresh water, when boiled, precipitate in the form of calcium and magnesium carbonates. A scale film appears, which has a low thermal conductivity. Scale conducts heat 20 times worse than cast iron. Each millimeter of scale layer requires 2-3% more fuel to be burned. Signs of scale are more heat exhaust gases and reduced temperature of heated water at the same fuel consumption. In addition, uneven temperature regime section walls. Cracks form, water flows into the furnace.
The first way to deal with scale is acidic. Mineral acids dissolve scale well, but destroy the metal. Therefore, first check the amount of scale in the boiler. To do this, in the warm season, water is drained from the system, the bolts are unscrewed and the covers on the frontal and rear sections are removed (see Fig. 1-9-28). Scrap off scale from any place on the inner surface to the metal. This will expose the relative thickness of the scale layer. Close the lids. If the layer thickness is more than 1-2 mm, the boiler is cleaned. For cleaning, a solution of inhibited hydrochloric acid is used. Special substances are added to it to slow down the reaction with cast iron. You can also use a 4% solution of pure hydrochloric acid. The solution is poured into a cold boiler, heated to + 60-80 ° C and kept for 20-30 minutes until the scale is loosened. Then half of the solution is drained through the return line pipe and compressed air is supplied from the compressor through the same pipe. Boiling should remove scale. This method of separating scale is called hydropneumatic and it is difficult to implement it at home, even if the acid solution is replaced with antiscale, since before pouring the solution into the boiler, the main riser and the return line should be disconnected from it. A pipe or a rubber hose is brought to the return line outlet, which must rise above the boiler so that the compressor can start working after the action of the solution on the inner walls of the sections and nipples. To release part of the solution before letting in compressed air, it is enough to tilt the rubber hose, but a tee and a valve are needed on the pipe at the outlet. In the outlet to the main riser, you need to put some kind of reflector so that the compressed air does not drive the solution out of the boiler, etc.
A safer and less complicated method of leaching scale, which is desirable to carry out for the entire heating system.
At the same time, a solution of soda ash is poured into the boiler. It is prepared at the rate of 20 g of soda per 1 liter of water. The solution is boiled for 10-20 hours. After cooling, it is released through the emptying pipe. In addition, you can remove the covers and clean the accessible surfaces with a wire brush or ruff.
Descaling is completed by washing in a countercurrent manner. To do this, let water through the hot distributing line in the direction of the main riser of the boiler.
When the boiler is cooled, the furnace is cleaned of slag and ash with the help of scrapers and metal brushes. They take out the plug and clean everything that has accumulated behind it. To do this, lower a weight on a rope into the chimney. For greater efficiency, work can be done together. When the weight is at the bottom of the chimney, open the plug, remove everything from it and tie a rag around the weight. The more fluffy the rag is, the better the chimney will be cleaned. In addition, you can make a hedgehog out of wire, tie a rope to it and together, moving the hedgehog up and down, quickly clean the chimney. The second person at the same time periodically pulls the rope through the pocket (Fig. 1-9-28.1-9-29) of the chimney. This method is applicable with a relatively straight chimney.
