Environment-friendly heating medium heating furnace for biomass gasification

Abstract

The utility model discloses an environment-friendly heating medium heating furnace for biomass gasification. The environment-friendly heating medium heating furnace comprises a furnace body, a plurality of spiral coil pipes and a gas burner, the plurality of spiral coil pipes are installed in an inner cavity of the furnace body, a smoke outlet is formed in the upper portion of the shell wall of the furnace body, a gas hearth is installed at the bottom of the furnace body and communicated with the inner cavity of the furnace body in a fluid mode, and the gas burner is installed on the side wall of the gas hearth. A fuel gas outlet is formed in the furnace top of the fluidized bed biomass gasification furnace and is connected with the fuel gas burner. The biomass heating furnace is high in safety, emission of flue gas pollutants is reduced, the utilization rate of biomass fuel and the heat efficiency of the heating furnace are improved, coking of the hearth and slagging of the heating surface of the coil pipe are avoided, and stable heat supply of the heating furnace is guaranteed.

Description

Technical Field

[0001] This utility model relates to a heat medium heater for heat exchange, and more particularly to an environmentally friendly heat medium heater for biomass gasification, belonging to the field of heater technology. Background Technology

[0002] Biomass fuel (BMF) refers to a new type of clean fuel made from agricultural and forestry waste as raw materials, processed through crushing, drying, and molding to produce pellets or other shaped environmentally friendly fuels with certain specifications and densities, which can be directly burned in heating furnaces.

[0003] Existing biomass-fired heat transfer furnaces, such as the structure disclosed in Chinese Utility Model Patent ZL202021485269.0, include a combustion chamber (furnace) and a shell installed above the combustion chamber. The combustion chamber is equipped with a reciprocating grate for burning biomass, and the walls of the combustion chamber are surrounded by refractory bricks. The shell is cylindrical and fluidly communicates with the combustion chamber. Radiant tube groups and convection tube groups are arranged in parallel within the shell.

[0004] Existing biomass-fired heat transfer boilers have the following drawbacks in practical use:

[0005] (1) Because biomass fuel has a low fixed carbon content, the combustion process lasts for a short time, it is not durable, and the combustion zone in the furnace is short. It usually burns out in the front position, which makes it easy for biomass fuel to overburn to the furnace hopper, causing fires and other safety accidents.

[0006] (2) After a large amount of volatile matter is released from biomass fuel, if the air supply is insufficient or the temperature is low, the volatile matter is easily broken down and released into carbon black, causing the furnace to emit black smoke; moreover, the grate is also very easy to be blocked by ash, resulting in the furnace emitting black smoke.

[0007] (3) Biomass fuel has low ash content, low density and easy to blow up, large fly ash content and contains more alkaline substances. Under high temperature combustion environment, alkaline substances and related inorganic elements are easy to form slag in the furnace or deposit on the heating surface of the coil in the form of fly ash particles, which affects the thermal efficiency of the heating furnace and corrodes the coil. Moreover, the ash melting point is low, which makes it easy to coke in the furnace and easy to slag on the heating surface of the coil.

[0008] (4) The moisture content of biomass fuel has a large deviation. When burning wet biomass pellets, the temperature field inside the furnace is low, making it difficult to ensure stable heating of the furnace. At the same time, the large amount of moisture also increases the volume of flue gas, which increases the heat loss of flue gas. Summary of the Invention

[0009] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide an environmentally friendly heat medium heater that is highly safe, can significantly reduce the emission of flue gas pollutants, can improve the utilization rate of biomass fuel and the thermal efficiency of the heater, can avoid coking in the furnace and slagging on the heating surface of the coil, and can ensure stable heat supply to the heater.

[0010] To solve the above-mentioned technical problems, this utility model adopts an environmentally friendly heat medium heating furnace for biomass gasification, including a furnace body, several spiral coils, and a gas burner; the several spiral coils are installed in the inner cavity of the furnace body, a flue gas outlet is provided on the upper part of the shell wall of the furnace body, a gas furnace is installed at the bottom of the furnace body, the gas furnace is fluidly connected to the inner cavity of the furnace body, the gas burner is installed on the side wall of the gas furnace, and it also includes a fluidized bed biomass gasifier, a gas outlet is provided on the top of the fluidized bed biomass gasifier, and the gas outlet is connected to the gas burner.

[0011] In a preferred embodiment of this utility model, a gas-solid cyclone separator, a gas dust collector, and a gas spray purifier are sequentially connected between the gas outlet of the fluidized bed biomass gasifier and the gas burner. The inlet of the gas-solid cyclone separator is connected to the gas outlet of the fluidized bed biomass gasifier, the outlet of the gas-solid cyclone separator is connected to the inlet of the gas dust collector, the bottom of the gas-solid cyclone separator is connected to the furnace of the fluidized bed biomass gasifier through a slag discharge pipe, the outlet of the gas dust collector is connected to the inlet of the gas spray purifier, and the outlet of the gas spray purifier is connected to the gas burner through a gas pipeline.

[0012] In a preferred embodiment of this utility model, a gas blower and several gas control valves are also installed on the gas pipeline.

[0013] In a preferred embodiment of this utility model, it further includes an air preheater, a blower, a flue gas mixing box, and a chimney. The flue gas outlet of the furnace body is connected to the chimney through a flue gas exhaust pipe. The air preheater is installed between the flue gas exhaust pipes. The air inlet of the air preheater is connected to the blower. The air outlet of the air preheater is connected to the gas burner through a combustion air pipe. One end of the flue gas mixing box is connected to the blower through a connecting pipe, and the other end of the flue gas mixing box is connected to the flue gas exhaust pipe through a flue gas return pipe.

[0014] In a preferred embodiment of this utility model, a spiral feeding mechanism is also included, through which biomass is fed into the furnace of the fluidized bed biomass gasifier. An ash collection tank is provided below the furnace of the fluidized bed biomass gasifier, and a gasifying agent inlet is provided on the side wall of the furnace.

[0015] By adopting the above structure, this utility model has the following beneficial effects:

[0016] When this utility model is in operation, biomass fuel is fed into the furnace of a fluidized bed biomass gasifier. The biomass fuel undergoes drying, dry distillation, oxidation, and reduction reactions in sequence within the furnace to generate combustible gas, mainly composed of carbon monoxide, hydrogen, and a small amount of methane, which is then discharged from the top of the furnace. In other words, this invention fully considers the characteristics of biomass fuel and changes its combustion method. The gas-fired furnace of the heating furnace does not directly burn biomass fuel, thus significantly reducing the drawbacks of flue gas pollutant emissions caused by traditional combustion methods. This invention first uses a fluidized bed biomass gasifier to generate combustible gas from biomass fuel, primarily composed of carbon monoxide, hydrogen, and a small amount of methane. This combustible gas then enters the gas-fired furnace of the heating furnace for combustion, effectively improving the utilization rate of biomass fuel and the thermal efficiency of the heating furnace. Furthermore, it avoids coking in the gas-fired furnace and slagging on the coil heating surfaces. Since the gas-fired furnace of this invention does not directly burn biomass fuel, it effectively avoids over-burning of biomass fuel in the furnace hopper, preventing fires and other safety accidents. This invention improves the safety performance of the heating furnace and extends its service life. By sending the combustible gas generated from biomass fuel into the gas-fired furnace for combustion, this gas-fired combustion method allows for precise control of the heating furnace's heat supply, ensuring stable and safe operation and external heat supply.

[0017] This invention provides a gas-solid cyclone separator, a gas dust collector, and a gas spray purifier between the gas outlet and the gas burner of a fluidized bed biomass gasifier. The inlet of the gas-solid cyclone separator is connected to the gas outlet of the fluidized bed biomass gasifier, the outlet of the gas-solid cyclone separator is connected to the inlet of the gas dust collector, the bottom of the gas-solid cyclone separator is connected to the furnace of the fluidized bed biomass gasifier through a slag discharge pipe, the outlet of the gas dust collector is connected to the inlet of the gas spray purifier, and the outlet of the gas spray purifier is connected to the gas burner through a gas pipeline. During operation, as the combustible gas generated from biomass fuel is discharged from the gas outlet at the top of the fluidized bed biomass gasifier, some incompletely burned biomass ash is also discharged. This ash, along with unburned carbon residue from the gas, is collected by a gas-solid cyclone separator and returned to the fluidized bed biomass gasifier for reuse. The combustible gas, after being processed by the gas-solid cyclone separator, enters a gas dust collector to remove any remaining lighter ash. It then enters a gas spray purifier, where fine dust and tar impurities are removed. Finally, the clean combustible gas is sent to the gas burner and into the gas furnace of the heating furnace for combustion. This structure not only ensures that the burner will not clog, but also ensures that the emissions of particulate matter, sulfur dioxide, and other pollutants in the flue gas after combustion are below national standard limits, better meeting the environmental impact assessment emission requirements of the thermal medium furnace system.

[0018] This invention comprises an air preheater, a blower, a flue gas mixing chamber, and a chimney. The flue gas outlet of the furnace body is connected to the chimney via an exhaust pipe. The air preheater is installed between the exhaust pipes, with its inlet connected to the blower and its outlet connected to the gas burner via a combustion air pipe. One end of the flue gas mixing chamber is connected to the blower via a connecting pipe, and the other end is connected to the exhaust pipe via a flue gas return pipe. With this structure, the invention introduces controlled-volume drawn-back flue gas into the flue gas mixing chamber at the blower inlet. After mixing with ambient temperature air, the mixture serves as combustion air in the gas burner, where it mixes with combustible gas to control the combustion state, achieving low-NOx combustion. This invention further ensures that the nitrogen oxides in the flue gas after combustion meet emission standards. Attached Figure Description

[0019] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the structure of an environmentally friendly heat medium heating furnace for biomass gasification according to this utility model. Detailed Implementation

[0021] See Figure 1 The diagram shows an environmentally friendly heat medium heater for biomass gasification, comprising a furnace body 1, several spiral coils 2, and a gas burner 3. The spiral coils 2 are installed inside the furnace body 1. Only one vertical spiral coil 2 is shown in the diagram. The two ends of the coil 2 are connected to the inlet heat medium manifold 1-3 and the outlet heat medium manifold 1-4 of the heater, respectively. A flue gas outlet 1-1 is provided on the upper part of the shell wall of the furnace body 1. A gas furnace chamber 1-2 is installed at the bottom of the furnace body 1. The furnace body 1 and the gas furnace chamber 1-2 are preferably circular. The gas furnace chamber 1-2 is fluidly connected to the inner cavity of the furnace body 1. The gas burner 3 is installed on the side wall of the gas furnace chamber 1-2. The diagram also includes a fluidized bed biomass gasifier 4. A gas outlet 4-1 is provided on the top of the fluidized bed biomass gasifier 4, and the gas outlet 4-1 is connected to the gas burner 3.

[0022] As a preferred embodiment of this utility model, such as Figure 1As shown, a gas-solid cyclone separator 5, a gas dust collector 6, and a gas spray purifier 7 are sequentially connected between the gas outlet 4-1 of the fluidized bed biomass gasifier 4 and the gas burner 3. The gas-solid cyclone separator 5, the gas dust collector 6, and the gas spray purifier 7 are all commercially available conventional equipment. The inlet 5-1 of the gas-solid cyclone separator 5 is connected to the gas outlet 4-1 of the fluidized bed biomass gasifier 4 through a pipe. The outlet 5-2 of the gas-solid cyclone separator 5 is connected to the inlet 6-1 of the gas dust collector 6 through a pipe. The bottom of the gas-solid cyclone separator 5 is connected to the furnace 4-2 of the fluidized bed biomass gasifier 4 through a slag discharge pipe 8. The outlet 6-2 of the gas dust collector 6 is connected to the inlet 7-1 of the gas spray purifier 7 through a pipe. The outlet 7-2 of the gas spray purifier 7 is connected to the gas burner 3 through a gas pipe 9. This structure not only ensures that the gas burner, valves, and other equipment will not become clogged, but also ensures that the emissions of pollutants such as particulate matter and sulfur dioxide in the flue gas after combustion are lower than the national standard limits, thus better meeting the environmental impact assessment emission requirements of the thermal medium furnace system. In this utility model, the bottom of the gas dust collector 6 is preferably connected to the furnace chamber 4-2 of the fluidized bed biomass gasifier 4 via pipe 25 and a screw feeding mechanism, and the bottom of the gas spray purifier 7 is preferably connected to the furnace chamber 4-2 of the fluidized bed biomass gasifier 4 via pipe 26 and a wastewater transfer pump.

[0023] As a preferred embodiment of this utility model, such as Figure 1 As shown, a gas blower 10 and several gas control valves 11 are also installed on the gas pipeline 9. The gas blower 10 is preferably a Roots blower, and the gas control valves 11 can be flow regulating valves, automatic shut-off valves, etc.

[0024] As a preferred embodiment of this utility model, such as Figure 1 As shown, the furnace also includes an air preheater 12, a blower 13, a flue gas mixing box 14, and a chimney 15. The flue gas outlet 1-1 of the furnace body 1 is connected to the chimney 15 via an exhaust pipe 16. The air preheater 12 is installed between the exhaust pipes 16. The air inlet 12-1 of the air preheater 12 is connected to the blower 13, and the air outlet 12-2 of the air preheater 12 is connected to the gas burner 3 via a combustion air pipe 17. One end of the flue gas mixing box 14 is connected to the blower 13 via a connecting pipe 18, and the other end of the flue gas mixing box 14 is connected to the exhaust pipe 16 via a flue gas return pipe 19. During operation, the blower 13 pumps ambient temperature air into the air preheater 12 for heat exchange, and then the hot air enters the gas burner 3, further improving the combustion efficiency of the furnace.

[0025] As a preferred embodiment of this utility model, such as Figure 1As shown, it also includes a screw feeding mechanism 20, which includes a motor 20-1 and a screw shaft 20-2. The motor 20-1 drives the screw shaft 20-2 to rotate and feed the biomass 21 into the furnace 4-2 of the fluidized bed biomass gasifier 4 by the screw feeding mechanism 20. An ash collection tank 22 is provided below the furnace 4-2 of the fluidized bed biomass gasifier 4, and a gasifying agent inlet 23 is provided on the side wall of the furnace 4-2 of the fluidized bed biomass gasifier 4. During operation, the biomass 21 in the silo 24 is fed into the furnace 4-2 of the fluidized bed biomass gasifier 4 by the screw feeding mechanism 20. The gasifying agent is preferably air, which enters the furnace 4-2 of the fluidized bed biomass gasifier 4 through the gasifying agent inlet 23, so that the biomass 21 is in a fluidized state. Under high temperature, the biomass 21 begins to be heated and completes the drying, dry distillation, oxidation, and reduction reactions in sequence to generate combustible gas mainly composed of carbon monoxide, hydrogen and a small amount of methane. The combustible gas is discharged from the gas outlet 4-1 at the top of the furnace. After being purified by the gas-solid cyclone separator 5, the gas dust collector 6 and the gas spray purifier 7, the combustible gas is drawn out by the gas blower 10 and then enters the gas burner 3 spray gun through the gas control valve 11, where it is burned in the gas furnace 1-2 to form high-temperature flue gas.

[0026] After trial use, this utility model has proven to be highly safe, reduce emissions of flue gas pollutants, improve the utilization rate of biomass fuel and the thermal efficiency of the heating furnace, prevent coking in the furnace and slagging on the heating surface of the coils, and ensure stable heating of the heating furnace, achieving good practical results.

Claims

1. An environmentally friendly heat medium heating furnace for biomass gasification, comprising a furnace body (1), a plurality of spiral coils (2), and a gas burner (3); the plurality of spiral coils (2) are installed in the inner cavity of the furnace body (1), a flue gas outlet (1-1) is provided on the upper part of the shell wall of the furnace body (1), a gas furnace chamber (1-2) is installed at the bottom of the furnace body (1), the gas furnace chamber (1-2) is fluidly connected to the inner cavity of the furnace body (1), and the gas burner (3) is installed on the side wall of the gas furnace chamber (1-2), characterized in that: It also includes a fluidized bed biomass gasifier (4), on the top of the fluidized bed biomass gasifier (4) is a gas outlet (4-1), and the gas outlet (4-1) is connected to the gas burner (3).

2. The environmentally friendly heat transfer medium heater for biomass gasification according to claim 1, characterized in that: Between the gas outlet (4-1) of the fluidized bed biomass gasifier (4) and the gas burner (3), there is a gas-solid cyclone separator (5), a gas dust collector (6), and a gas spray purifier (7) connected in sequence. The inlet (5-1) of the gas-solid cyclone separator (5) is connected to the gas outlet (4-1) of the fluidized bed biomass gasifier (4), and the outlet (5-2) of the gas-solid cyclone separator (5) is connected to the inlet (6-1) of the gas dust collector (6). The bottom of the gas-solid cyclone separator (5) is connected to the furnace (4-2) of the fluidized bed biomass gasifier (4) through the slag discharge pipe (8). The outlet (6-2) of the gas dust collector (6) is connected to the inlet (7-1) of the gas spray purifier (7), and the outlet (7-2) of the gas spray purifier (7) is connected to the gas burner (3) through the gas pipe (9).

3. The environmentally friendly heat transfer medium heater for biomass gasification according to claim 2, characterized in that: A gas blower (10) and several gas control valves (11) are also installed on the gas pipeline (9).

4. The environmentally friendly heat medium heater for biomass gasification according to claim 1, characterized in that: It also includes an air preheater (12), a blower (13), a flue gas mixing box (14), and a chimney (15). The flue gas outlet (1-1) of the furnace body (1) is connected to the chimney (15) through a flue gas duct (16). The air preheater (12) is installed between the flue gas ducts (16). The air inlet (12-1) of the air preheater (12) is connected to the blower (13). The air outlet (12-2) of the air preheater (12) is connected to the gas burner (3) through a combustion air duct (17). One end of the flue gas mixing box (14) is connected to the blower (13) through a connecting pipe (18). The other end of the flue gas mixing box (14) is connected to the flue gas duct (16) through a flue gas return pipe (19).

5. The environmentally friendly heat transfer medium heater for biomass gasification according to any one of claims 1 to 4, characterized in that: It also includes a screw feeding mechanism (20), and biomass (21) is fed into the furnace (4-2) of the fluidized bed biomass gasifier (4) by the screw feeding mechanism (20). An ash collection tank (22) is provided below the furnace (4-2) of the fluidized bed biomass gasifier (4), and a gasifying agent inlet (23) is provided on the side wall of the furnace (4-2) of the fluidized bed biomass gasifier (4).

Images