RU2763984C1 - Long burning heating stove - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: invention relates to heat power engineering, namely to furnace heating systems based on solid fuel stoves, and can be used to create simple heating systems with improved technical and operational characteristics. A long-burning heating furnace contains a housing with a loading and ash doors and a chimney pipe, an inlet air duct, an inlet damper driven by a thermostat, a grate, an ash box, a flue gas temperature control damper and an external casing located on the body with an air gap, a smoke exhaust damper, a heat exchange a cavity that includes an afterburner, which turns into an outlet gas channel, separated by a partition with a damper for controlling the temperature of flue gases, located in the branch pipe and a bypass gas channel connected to the outlet gas channel on both sides of the partition, and by the opposite ends with a transition gas channel with cleaning, while the heat exchange cavity is connected to the body with an air gap and communicates with it in the lower part through the gas window, and in the upper part through a smoke exhaust flap, and the inlet air duct is divided by a partition, most of it is connected to the primary air supply channel, and the smaller part to the secondary air channel, in this case, the secondary air channel communicates with the afterburner through holes in its base, and the primary air channel passes under the ash pan and communicates with the grate cavity through a slot in the side wall of the ash pan.

EFFECT: increasing the efficiency of solid fuel combustion, expanding the range of restructuring of the generated power, increasing the duration of combustion, increasing the durability, reliability and operational safety.

6 cl, 2 dwg

Description

SUBSTANCE: invention relates to thermal power engineering, namely to furnace heating systems based on solid fuel furnaces and can be used to create simple heating systems with improved technical and operational characteristics.

Known heating furnaces with extended burning time (US patent No. 4230090, European patent No. 0231424, German application No. OS 3602285, RF patent No. 2001352, 2001353, 2097660, RF utility model No. 76702). In order to increase the efficiency of fuel combustion, these furnaces use the principle of its gasification followed by afterburning of combustible gases. However, such furnaces have a burning time not exceeding 8-10 hours, and at the minimum generated thermal power. This is due to the fact that in the combustion chamber all the loaded fuel is in the zone of high temperatures, since it is burned from below, while at the same time it is gasified. Moreover, the pyrolysis of the fuel will be the more intense, the greater the thermal power produced and, as a result, the higher the temperature in the combustion chamber. And since a limited volume of air is supplied for afterburning the resulting combustible gases (determined by a given thermal power), a significant part of the combustible gases, particles in the liquid and solid phases do not burn out due to the relatively low temperature in the furnace, especially in peripheral areas and the lack of a sufficient volume of oxygen. and go into the chimney, reducing the efficiency of the stove. This factor, as well as the possibility of switching to an uncontrolled mode of operation with a large amount of fuel, limits the possibility of increasing the burning time of these furnaces by increasing the combustion chamber and the volume of fuel loaded into it. In addition, in furnaces of known designs, the range of changes in the generated power is relatively small. This is due to the fact that the maximum power is limited by the allowable losses carried away by hot flue gases, and the minimum power is limited by the minimum allowable flue gas temperature at which condensate does not form and soot deposits in the chimney do not sharply increase. In addition, these furnaces, due to the lack of adjustment of the flue gas temperature at capacities above the minimum, as a rule, have a relatively high flue gas temperature. This reduces the efficiency of the furnace at capacities greater than the minimum, due to heat losses through the chimney, and at low capacities due to chemical underburning.

Known heating furnace (RF patent No. 2541968 dated 01/19/2015), selected as a prototype, in which the duration of fuel burning is increased by implementing the method of burning fuel from top to bottom. In this furnace, the air in the combustion chamber is supplied to the combustion zone through the inlet air duct and movable windows in two vertical air ducts on top of the fuel under the driver's windows. In this case, the combustion of fuel occurs from top to bottom. The output of flue gases is carried out through the upper and lower chimney pipes. Depending on the required temperature of the flue gases, the ratio of hot and cooled flue gases is changed using a damper in the upper chimney pipe. Power stabilization is carried out with the help of a thermostat, the operation of which is based on the use of a change in the size of the case from temperature.

The disadvantages of the known design are the relatively low efficiency and, as a consequence, the duration of combustion. This is due to the fact that in almost the entire range of generated powers there is a large chemical underburning. At low powers, it is due to the low temperature of the pyrolysis gases (not sufficient for their ignition) and the lack of oxygen for their oxidation, and at high powers, a significant percentage of unburned pyrolysis gases through the lower chimney pipe. In this furnace, there is also a relatively small range of power changes, which is due to the small range of permissible flue gas temperatures. At minimum power, the temperature of the flue gases should not be lower than the allowable temperature for the chimney, and at high powers it is determined by the allowable heat losses with flue gases that cannot be cooled in this design to the required temperatures due to the limited heat exchange surface of the furnace body. In addition, the presence of moving elements in the furnace reduces the reliability and durability of the furnace.

The technical result consists in increasing the efficiency of burning solid fuel, expanding the range of adjustment of the generated power, increasing the duration of combustion, increasing durability, reliability and operational safety.

The technical result is achieved by the fact that the heating furnace comprises a housing with a loading and ash door and a chimney pipe, an inlet air duct, an inlet damper driven by a thermostat, a grate, an ash drawer, a flue gas temperature control damper and an outer casing placed on the housing with an air gap, a smoke exhaust damper, a heat-exchange cavity, including an afterburner, passing into the outlet gas channel, divided by a partition with a flue gas temperature control damper, located in the branch pipe and a bypass gas channel connected to the outlet gas channel on both sides of the partition, and at opposite ends with a transitional gas channel with cleaning, while the heat exchange cavity is connected to the body with an air gap and communicates with it in the lower part through the gas window, and in the upper part through the smoke exhaust damper, and the inlet air duct is divided by a partition, most of it is connected to the primary air supply channel, and smaller to the secondary air channel, while the secondary air channel communicates with the afterburner chamber through holes in its base, and the primary air channel passes under the ash pan and communicates with the grate cavity through a slot in the side wall of the ash pan.

The essence of the invention is illustrated in Fig. 1 and 2, where simplified views of the furnace are shown in transverse and longitudinal sections and indicated: 1 - furnace body, 2 - loading door 3 - ash door, 4 - chimney pipe, 5 - gas window, 6 - afterburner chamber, 7 - outlet gas channel, 8 - partition, 9, 10 - bypass gas channel with descending 9 and ascending 10 sections, 11 - transitional gas channel, 12 - cleaning, 13 - flue gas temperature control damper, 14 - branch pipe, 15 - damper actuator, 16 - reflector, 17, 18, 19 - air gap, 20 - inlet air duct, 21 - inlet air duct baffle, 22 - primary air channel, 23 - slot in the side wall of the ash pan, 24 - secondary air channel, 25 - holes in the afterburner chamber, 26 - brackets over the holes, a two-stage damper, consisting of a large 27 and a small 28 damper, 29 - a hole in a large damper, 30 - a thermostat rocker, 31 - a counterweight, 32 - a rocker axis, 33 - a pusher with an adjusting knob, 34 - an input drive dampers, 35 - smoke damper pressure, 36 - smoke damper drive, 37 - smoke damper control knob, 38 - grate, 39 - ash pan, 40 - ash drawer, 41 - removable cover, 42 - casing.

Furnace body 1 (and other elements of the furnace) is made of steel with the necessary wall thickness and heat resistance to ensure the required service life of the furnace. In the upper part of the case there is a loading 2 door, and in the lower part there is an ash door 3. The doors must be made gas-tight in the closed position by installing appropriate seals. The ash door 3 is intended for servicing the ash drawer and for igniting the fuel located on the grate 38. The chimney pipe 4 is used for its intended purpose for removing flue gases from the furnace and has no special features. In the lower part of the housing 1 in the side or rear wall (depending on the location of the housing relative to the heat exchange cavity) there is a gas window 5 through which flue gases are discharged into the heat exchange cavity, which, in turn, contains an afterburner chamber 6, an outlet gas channel 7, with a partition 8, a bypass channel, consisting of their descending 9 and ascending 10 parts, connected to the transition channel 11 with cleaning 12. Afterburner 6 is used to burn pyrolysis gases coming from the burning volume of fuel in housing 1, products of fuel decomposition and exothermic reaction in liquid and solid phases. The chamber 6 is installed with an air gap 17 relative to the housing 1 and can be additionally thermally insulated. To improve the combustion of these components, a turbulator can be installed to the afterburner 6, which improves their mixing with the secondary air entering through the holes 25. A blind partition is installed in the outlet gas channel 7, in the center of which there is a branch pipe 14 with a flue gas temperature control damper 13, controlled by the drive 15. The area of the flow section of the branch pipe 14 is selected not less than the cross-sectional area of the chimney. A reflector 16 is installed in the outlet gas channel 7 above the afterburner 6, which reduces the resistance to gas flow and prevents overheating of the removable roof 41. air gaps between adjacent pipes and housing 1. Sections 9 and 10 communicate with each other through a through gas channel 11, which is installed with an air gap 19. On one of the side walls in the channel 11, a cleaning 12 is made, in the form of a hole closed by a lid. To increase the efficiency of heat removal, turbulators can be installed in channels 9 and 10. The inlet air duct 20 is made of a rectangular or square pipe, the area of which must ensure the passage of the required air volume for the operation of the furnace at all capacities. A two-stage damper (RF patent No. 2651393) is installed on the inlet air duct, consisting of a large 27 and a small 28 damper. A hole 29 is made in the large damper through which air is supplied when the large damper 27 is closed and the air flow is controlled using a small damper 28. ) primary air 22 and secondary air channel 24. Primary air under the grate 38 is supplied through slot 23, passing through channel 22 under the ash pan 39, which houses the ash box 40. Secondary air is supplied to the afterburner 6 through holes 25, which are closed with brackets 26 preventing ash from entering the secondary air channel 24. The ratio of primary and secondary air supplied through the small damper 28 and hole 29 to the air ducts 22 and 24 is several times greater than the same ratio through the large damper. This allows you to maintain a more optimal excess air ratio at various capacities. The thermostat contains a rocker arm 30 with an axis of rotation 32 placed on the casing 42, a counterweight 31 and a pusher with an adjusting knob 33 located on the body 1 of the furnace, in its upper part. The rocker arm 30 is connected to the inlet gate through the drive 34. The drive 34 can be made, for example, from a cable or a chain. The smoke damper 35 is used to remove flue gases during reloading of fuel, controlled by the actuator 36 and the control knob 37, for example, in the form of a plate (flag). Removable cover 41 serves to gain access to the smoke exhaust damper and the internal cavities of the heat exchange cavity in order to install and replace the turbulator and reflector 16, to clean the internal surfaces and the smoke exhaust damper. The casing 42 is designed to significantly reduce the thermal radiation of the furnace and improve its hygienic and fire safety. The casing is placed with an air gap relative to the casing and the heat exchange cavity, so as to ensure free circulation of the air heated by the furnace. The casing 42 can be made, for example, from a metal frame with a heat-insulating coating and contain decorative elements on the outer surface. For example, a glass fiber foil felt may be used as a coating, facing the reflective coating towards the body. Openings can be made in the cover of the casing, closed with removable covers, for installation directly on the oven of containers for cooking or heating food. To improve the heat transfer of the furnace, as well as its aesthetic perception, a part of the side wall of the casing under the cover and near the bypass gas channel is perforated, in the form of a decorative pattern.

The proposed furnace works as follows. After loading through the loading door 2 of the fuel into the furnace, it closes. The smoke damper 35 is also closed by pulling out and turning the control knob 37. In this position, the plate of the control knob 37 blocks the door 2, preventing it from being accidentally opened without ventilating the furnace body. Fuel is ignited through door 3 and it closes. The damper 27 opens approximately at an angle of 10-20 ° using the adjusting knob of the pusher 33. Combustion air is supplied to the fuel through the open inlet damper, the inlet air duct 20, the primary air channel 22, the slot 23 under the grate 38. When the inlet air passes through relatively long air channels (during the operation of the furnace), it is heated and enters under the heated grate, which improves the conditions for the exothermic reaction. Due to the fact that the grate 38 occupies a large part of the bottom, the air is distributed over it relatively evenly, which ensures its better mixing with the decomposition products of the fuel and the exothermic reaction. However, due to the presence of peripheral low-temperature zones, non-uniform combustion of various sections of the volume of simultaneously burning fuel, the flue gases contain a significant percentage of unburned pyrolysis gases and particles of decomposition products in the liquid and solid phases, the ignition temperature of which is lower than required (more than 600 ° C) . Therefore, heated secondary air is supplied to the afterburner 6 together with the flue gases through the holes 25. Due to the limited cross section of the chamber 6 and its relatively large length, quite efficient combustion of unburned particles occurs in it. This is also facilitated by the placement of a turbulator in the afterburner chamber, which ensures the mixing of air oxygen and previously unburned fuel particles. At the same time, temperatures above 1000°C can develop at the outlet of chamber 6, which ensures sufficiently efficient combustion of unburned pyrolysis gases and fuel particles entering chamber 6. The gas flow from the chamber 6 reflected from the reflector 16 is directed to the outlet gas channel 7. Depending on the operating mode of the furnace, the gas flow is directed through various channels. So, when operating at low power, the gas flow is directed through the pipe 14 and the open damper 13 directly into the chimney through the pipe 4. As a result, the heated heat exchange surface of the furnace is minimal and, accordingly, the heat output of the furnace will also be minimal. At the same time, the intensity of fuel combustion is kept to a minimum. At high combustion intensity, the flue gas temperature control damper 13 is set to the closed position using the handle 15, and the flue gases are directed into the chimney through the bypass and transition gas channels 9, L, 10. Since the surface area of these channels is many times greater than the surface area of the short outlet gas channel 7 , then the radiated thermal power is many times greater than the minimum (in practice, this ratio can reach more than 10 times). Due to the fact that the flue gases pass along a long path, giving up their thermal energy to the heat exchange surface, they cool down to low temperatures. This ensures a high efficiency of the furnace, which is important from an operational point of view for a durable heater. When generating intermediate capacities, when the temperature of the flue gases is below the maximum allowable (at which condensate and soot deposits do not form in the chimney), damper 13 adjusts the ratio of hot and cooled flue gases passing along the short and long paths and thereby maintaining the temperature of the flue gases close to the minimum allowed. This ensures that the heat losses carried away by flue gases are minimized, which further increases the efficiency of the furnace. In addition, the range of restructuring of the generated power is expanding, which, in turn, increases the convenience of operating the furnace during various periods of the heating season. After ignition of the furnace and its heating, due to thermal expansion, the dimensions of the housing increase, relative to the casing and the pusher 33 rotates the rocker arm 30 on the axis 32, while the inlet damper 27 is covered through the drive 34. And when the housing cools down, the pusher 33 moves down, the rocker arm 30 is under the counterweight 31 rotates and opens the inlet damper 27 through the drive. If it is necessary to change the generated power, the adjusting knob of the pusher 33 changes the opening angle of the damper 27. At low power, the large damper 27, as a rule, closes completely, and the small 28 remains ajar by a few millimeters. At high power, the large damper 27 can be opened at a small angle, and the small damper 28 is fully open. In the future, the dampers are controlled automatically by the thermostat. The fuel in the furnace burns mainly only in the layer below the level of the outlet gas window 5, therefore, as it burns out, the overlying layers fall to the place of the burnt one, and so the combustion of all the fuel loaded into the furnace sequentially occurs. With this mode of burning not only, but a limited amount of fuel, it is mainly ensured that the optimal excess air ratio and, therefore, the most efficient combustion, and the afterburning of pyrolysis gases and other volatile fuel components in the high-temperature zone of the afterburner chamber 6 minimizes the percentage of chemical underburning. To optimize the value of the excess air coefficient in various operating modes of the furnace, it provides a change in the ratio of primary and secondary air depending on the generated power, which further reduces heat losses during its operation. In general, due to the consistent more efficient combustion of a relatively large volume of fuel, a significant increase in the duration of combustion is achieved (in prototypes, it reaches several tens of hours).

When reloading the operating furnace with fuel, the inlet dampers 27, 28 are first closed, the flue gas temperature control damper 13 opens, the furnace body is ventilated by opening the smoke exhaust damper 35 by turning the flag 37 of the drive 36. After that, the loading door 2 opens and the fuel is loaded into the furnace. Then the loading door 2 is closed, the smoke exhaust damper 35 is closed and the flag 37 mutually locks the closed smoke exhaust damper 35 and the loading door 2, and the damper 13 and the inlet two-stage damper are set to their previous position. This prevents flue gases from entering the room and ensures the operational safety of the furnace. Fire safety is ensured by the use of a casing that excludes the effect of thermal radiation on surrounding objects (the air in the room is heated by convective heating from the heat exchange surfaces of the furnace).

Thus, in the proposed design of the furnace, in comparison with the prototype and other analogues, an increase in the efficiency of solid fuel combustion is ensured due to the gradual combustion of a large volume of fuel with a close to optimal excess air ratio, afterburning of pyrolysis gases and the possibility of maintaining flue gas temperatures at extremely low values. . A consequence of the high efficiency of combustion of solid fuels is a long burning time, which is several times higher than that of analogues. The possibility of changing the effective heat exchange surface over a wide range provides a significant expansion of the range of changes in the generated power, while maintaining a sufficiently high efficiency of fuel combustion. The relatively large heat-exchange surface of the furnace makes it possible to reduce the average heating temperature of the casing and the heat-exchange cavity and thereby ensure a longer service life of the furnace and, in general, increase its reliability, including due to the absence of moving elements in the high-temperature zone.

The level of development is at the stage of organizing mass production of a model range of long-burning furnaces with different thermal power.

Claims (6)

1. A long-burning heating furnace, containing a body with a loading and ash door and a chimney pipe, an inlet air duct, an inlet damper driven by a thermostat, a grate, an ash drawer, a flue gas temperature control damper and an outer casing placed on the body with an air gap, different the fact that it contains a smoke exhaust damper, a heat exchange cavity, including an afterburner, passing into the outlet gas channel, separated by a partition with a flue gas temperature control damper, located in the branch pipe, and a bypass gas channel connected to the outlet gas channel on both sides of the partition, and opposite ends with a transitional gas channel with cleaning, while the heat exchange cavity is connected to the body with an air gap and communicates with it in the lower part through the gas window, and in the upper part - through the smoke exhaust damper, and the inlet air duct is divided by a partition, most of it is connected to the channel filing first fresh air, and the smaller one - to the secondary air channel, while the secondary air channel communicates with the afterburner chamber through holes in its base, and the primary air channel passes under the ash pan and communicates with the grate cavity through a slot in the side wall of the ash pan. 2. A long-burning heating furnace according to claim 1, characterized in that a turbulator is installed in the afterburner. 3. A long-burning heating furnace according to claim 1, characterized in that a reflector is placed above the afterburner chamber. 4. The long-burning heating furnace according to claim 1, characterized in that part of the top cover above the gas outlet and the smoke exhaust damper is removable. 5. A long-burning heating furnace according to claim 1, characterized in that turbulators are installed in the bypass gas channel. 6. A long-burning heating furnace according to claim 1, characterized in that part of the side wall of the casing under the cover and near the bypass gas channel is perforated in the form of a decorative pattern.

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