Heating Device Using Wood Fuel

Abstract

The utility model relates to thermal power engineering, particularly to heating devices in which wood fuel undergoes high-temperature gasification (pyrolysis). The problem which the claimed utility model addresses is that of the consistent and environmentally clean combustion of wood fuel possessing a natural (that is, high) moisture content. The technical result is achieved in that the device includes a vertically-oriented additional gas duct through which the moisture contained in the fuel is removed in the form of of steam from the upper part of a fuel hopper to a flame in an afterburn chamber, wherein carbon monoxide mixed with steam is burned off and does not enter the atmosphere.

Claims

1. A heating device using wood fuel, comprising placed in a single vertically oriented housing: a fuel hopper and a gasification chamber underneath the fuel hopper, an afterburner, a primary and a secondary air supply duct, a water tank, inside which there is a fire-tube heat exchanger connected to an outlet chimney, wherein the heating device contains at least one vertically oriented additional gas duct having an upper and a lower opening, the upper opening is located at upper part of internal volume of the fuel hopper, and the lower opening is located at the afterburner, where the combustion of the flame ends.

2. The heating device using wood fuel according to claim 1, wherein at least one gas collection funnel is installed in upper part of the fuel hopper, and wherein the upper opening of the at least one vertically oriented additional gas duct is connected to upper part of the at least one gas collection funnel.

3. The heating device using wood fuel according to claim 1, wherein a shut-off and control valve is embedded in the additional gas duct.

4. The heating device using wood fuel according to claim 1, wherein the at least one vertically oriented additional gas duct is at least partially located inside the water tank, while a container for collecting condensate with a device for draining condensate out of the heating device is located at bottom of the part of the additional gas duct that is placed in water.

Description

[0016] The design of the claimed heating device is illustrated by the sketch on FIG. 1, which shows a vertical section of the version having a gas collection funnel but no condensate collecting tank.

[0017] The heating device comprises a solid fuel hopper 1 with a loading hatch 12, gasification zone (chamber) 2 located in the lower part of the hopper, afterburner 3, primary air supply ducts 4, secondary air supply ducts 5, water tank 6 housing a fire-tube heat exchanger 7 connected to the smoke exhauster 8 via the outlet chimney. The additional gas duct 9, connected in its upper part to the gas collection funnel 10, passes downwards to the afterburner, and its lower opening is located at the end of the flame (along the direction of movement of combustible gases).

[0018] The heating device operates as follows. Wood fuel 11 (for example, firewood or wood chips with a natural moisture content) is loaded into the hopper 1 through the loading hatch 12 on the side wall of the hopper. Due to gravity, the wood fuel falls down, successively passing through the drying zone (upper part of the hopper), the dry distillation zone (lower part of the hopper) and enters the gasification zone (chamber) 2. In this zone, the fuel is ignited from an external source (not shown) and burns in the atmosphere of primary air supplied to the gasification and primary combustion zones through duct 4.

[0019] Combustible gases (hydrogen, methane, carbon monoxide), formed as a result of primary pyrolysis of wood and chemical reduction after contact with hot coal, enter the afterburner 3, where they are mixed with secondary air entering through duct 5 and burned in the flame 13. The hot combustion products from the afterburner enter the fire tube 7, where they transfer their heat to the water in tank 6 and are then discharged into the exhaust pipe with a smoke exhauster 8, from there into the chimney (not shown) and then to the atmosphere.

[0020] Moisture evaporating from raw wood in the form of water vapor with a temperature of 100-120 C. rises (floats) to the upper part of the fuel hopper 1 and enters the additional gas duct 9 through a gas collection funnel 10. The movement of water vapor from the top of the additional gas duct 9 to the bottom occurs under the influence of rarefaction (differential pressure) created by the smoke exhauster 8 in the afterburner 3; furthermore, the difference in the specific gravity of the steam having a temperature of 100-120 C. and the combustion products in the afterburner having a temperature of more than 800-900 C. contributes to the movement of steam from the top of the additional gas duct 9 to the bottom. The removal of or at least a significant reduction in the amount of water vapor in the primary combustion zone, contributes to the sustainable burning of wood fuel.

[0021] Water vapor through the additional gas duct 9 is supplied to the end point of the torch 13 (in the direction of movement of the combustible gases). In this zone, the mixing of combustible gases and the secondary air has already been completed, and therefore the appearance of water vapor will not interfere with the combustion process. Carbon monoxide, a certain amount of which will inevitably be present in the stream of water vapor, caught in the zone of high temperatures (more than 900 C.) in the most heated part of the torch 13 burns in the secondary air.

[0022] The complete afterburning of carbon monoxide is also promoted by water vapor, which reacts with carbon monoxide at high temperatures according to the formula: H2O+CO=H2+CO2. As a result of the reaction, two gases harmless to human health are formed (hydrogen and carbon dioxide). This reaction is accompanied by heat, and thus does not interfere with the main combustion process in the afterburner. In addition, at high temperatures, water vapor reacts with the smallest particles of unburned coal (soot) and burns them according to the formula: H2O+C=H2+CO, and an insignificant amount of carbon monoxide resulting from the reaction is burned according to the reactions described above. The possibility for destroying (afterburning) the smallest particles of coal (soot) is very important, because according to modern data, these particles are a strong carcinogen, and their content in flue gases should be strictly limited.