Device for producing low-tar biomass gas by circulating fluidized bed air gasification furnace and use method

Abstract

The invention provides a circulating fluidized bed air gasifier low-tar biomass gas production device and a use method, the circulating fluidized bed air gasifier low-tar biomass gas production device comprises a gasifier lifting pipe, an upper outlet of the gasifier lifting pipe is connected with the top of a cyclone separator, and the bottom of the cyclone separator is connected with a U-shaped return feeder through a vertical pipe; an outlet material returning inclined pipe of the U-shaped material returning device is communicated with the lower portion of the gasification furnace lifting pipe, a catalyst opening is formed in the middle of the outlet material returning inclined pipe of the U-shaped material returning device, an outlet in the upper portion of the cyclone separator is connected with a cyclone dust collector, and an ash discharging pipe is arranged at the bottom of the cyclone dust collector. The catalyst is added to the inclined tube of the U-shaped return feeder, the catalyst, a bed material and a biomass raw material are fully mixed in a dense-phase region, the fluidization state is improved, the biomass and the catalyst are distributed at the top of the bed layer, the retention time of tar in the dense-phase region is prolonged, and thermal cracking of the tar is promoted. The temperature at the joint of the U-shaped return feeder and the riser of the gasification furnace is relatively high and is closer to the thermal cracking temperature, so that the gasification efficiency is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of biomass gasification, and in particular to a device for producing low-tar biomass gas in a circulating fluidized bed air gasifier and a use method thereof. Background Art

[0002] Biomass gasification is an important technical approach to biomass energy utilization. Through drying, pyrolysis, oxidation and reduction processes, biomass is converted into syngas containing combustible gases such as CO, CO2, CH4 and H2. However, the problem of tar generation during the gasification process has seriously hindered the industrial application of the technology. Tar is mainly composed of single-ring to five-ring aromatic compounds and other oxygen-containing hydrocarbons, which are easily condensed at low temperatures, leading to blockage, corrosion and wear of the gasification device, and increasing maintenance costs.

[0003] At present, tar removal methods include physical and chemical methods. The physical method transfers tar by condensation, which cannot fundamentally solve the problem; the chemical method can effectively decompose tar and improve gasification efficiency through catalysts and thermal cracking. However, existing synthetic catalysts are easy to deactivate and have high costs, while natural catalysts such as dolomite and olivine have the advantages of low cost and durability, but their use methods still need to be optimized. Therefore, it is urgent to develop a low-cost, high-efficiency, and easy-to-operate technical device to effectively reduce the tar generation and accumulation problems in the biomass gasification process. Summary of the invention

[0004] The object of the present invention is to provide a circulating fluidized bed air gasification furnace to produce low-tar biomass gas and a method for using the device, by adding a natural catalyst and optimizing the device structure, to reduce the generation and accumulation of tar, improve gasification efficiency, and reduce operating costs.

[0005] According to one object of the present invention, the present invention provides a circulating fluidized bed air gasification furnace low-tar biomass gas production device, including a gasifier riser, a cyclone separator and a U-shaped return feeder, wherein the upper outlet of the gasifier riser is connected to the top of the cyclone separator, the bottom of the cyclone separator is connected to the U-shaped return feeder through a vertical pipe, the outlet return material inclined pipe of the U-shaped return feeder is communicated with the lower part of the gasifier riser, the outlet return material inclined pipe of the U-shaped return feeder is provided with a catalyst port in the middle, the upper outlet of the cyclone separator is connected to a cyclone dust collector, and the bottom of the cyclone dust collector is provided with an ash discharge pipe.

[0006] Furthermore, the side wall of the gasifier riser is arranged with two-stage feed inlets and bed material inlets.

[0007] Furthermore, an air distribution plate and an air hood are provided at the bottom of the gasifier riser, and a slag discharge pipe is provided at the bottom of the gasifier riser.

[0008] Furthermore, a combustion chamber is disposed below the air distribution plate, and a gasification air inlet and an ignition oil gun are disposed on a side wall of the combustion chamber.

[0009] Furthermore, the combustion chamber adopts an under-bed ignition method to maintain a high-temperature environment for the gasification reaction.

[0010] Furthermore, a return air distribution plate and an air hood are provided at the bottom of the U-shaped return material device.

[0011] Furthermore, the catalyst is a natural ore catalyst, including dolomite or olivine.

[0012] Furthermore, the catalyst is added through a catalyst port to participate in the tar thermal cracking reaction.

[0013] Furthermore, the cyclone separator is used to separate the biomass gas from solid particles, and the solid particles flow back to the U-shaped return feeder.

[0014] According to another object of the present invention, the present invention provides a method for using the above-mentioned circulating fluidized bed air gasification furnace to produce low-tar biomass gas, comprising the following steps:

[0015] The biomass raw material is fed into the gasifier riser through the feed port and enters the fluidized state together with the bed material through the bed material port;

[0016] The gasified biomass gas and solid particles enter the cyclone separator. After separation, the particles flow back to the U-shaped return feeder through the vertical pipe. The gas enters the cyclone dust collector for further purification. The purified gas is transported to subsequent application equipment through the exhaust pipe.

[0017] A catalyst port is provided in the middle of the inclined tube of the U-shaped returner, and the catalyst and the reflux particles are fully mixed in the high temperature area to decompose the tar through thermal cracking.

[0018] The ash discharge pipe at the bottom of the cyclone dust collector removes the solid particle ash produced during the gasification process and further purifies the biomass gas.

[0019] The technical solution of the present invention adds a catalyst to the inclined tube of the U-shaped returner, so that the catalyst, bed material and biomass raw materials are fully mixed in the dense phase area, improving the fluidized state, and the biomass and catalyst are distributed on the top of the bed layer, which is beneficial to prolong the residence time of tar in the dense phase area, thereby promoting the thermal cracking of tar. The temperature at the connection between the U-shaped returner and the gasifier riser is relatively high. Adding a catalyst in the inclined tube of the U-shaped returner is also closer to the thermal cracking temperature, at 750 to 850 degrees. The calorific value of the combustible gas is high, which effectively improves the gasification efficiency. The biomass gas collected by the cyclone dust collector of the present invention is cooled by the thermal oil heat exchanger and then sent to the boiler for mixed combustion. During operation, there is no problem of tar blockage in the gas pipeline, and there is no tar condensation on the pipe wall of the thermal oil heat exchanger and the booster fan blades, thereby reducing maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0022] In the figure: 1. Gasification furnace lifting pipe; 2. Feed inlet; 3. Bed material inlet; 4. Air hood; 5. Slag discharge pipe; 6. Combustion chamber; 7. Ignition oil gun; 8. Cyclone separator; 9. U-shaped return feeder; 10. Return air distribution plate; 11. Catalyst inlet; 12. Cyclone dust collector; 13. Ash discharge pipe. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Example 1

[0027] like Figure 1 As shown,

[0028] A circulating fluidized bed air gasifier producing low-tar biomass gas device comprises a gasifier riser 1,

[0029] The upper outlet of the gasifier riser 1 is connected to the top of the cyclone separator 8, the bottom of the cyclone separator 8 is connected to the U-shaped return material device 9 through a vertical pipe, and the outlet return material inclined pipe of the U-shaped return material device 9 is connected to the lower part of the gasifier riser 1;

[0030] A catalyst port is provided in the middle of the inclined tube of the U-shaped return feeder 9 for adding natural catalyst;

[0031] The upper outlet of the cyclone separator 8 is connected to the cyclone dust collector 12, and the bottom of the cyclone dust collector 12 is provided with an ash discharge pipe 13;

[0032] The side wall of the gasifier riser 1 is arranged with a two-stage feed port 2 and a bed material port 3, the bottom of the gasifier riser 1 is provided with an air distribution plate, an air hood 4 and a slag discharge pipe 5, below the air distribution plate is a combustion chamber 6, and the side wall of the combustion chamber 6 is provided with a gasification air inlet and an ignition oil gun 7.

[0033] Through the above structure, the catalyst, biomass and bed material are fully mixed in the present invention, which effectively prolongs the residence time of tar in the dense phase zone, promotes thermal cracking of tar, and significantly improves gasification efficiency.

[0034] When the present invention is used:

[0035] The biomass raw material is fed into the gasifier riser 1 through the feed port 2 and enters the fluidized state together with the bed material through the bed material port 3. The air distribution plate and the air hood 4 arranged at the bottom of the gasifier riser 1 are used to evenly distribute the gasification agent air to ensure sufficient reaction.

[0036] The combustion chamber 6 below the air distribution plate adopts an under-bed ignition method. After the combustion chamber 6 is ignited by an ignition oil gun 7, the heat is transferred to the gasifier riser 1 to maintain the temperature required for the gasification reaction.

[0037] The gasified biomass fuel gas and solid particles enter the cyclone separator 8. The separated particles flow back to the U-shaped return feeder 9 through the vertical pipe. The fuel gas enters the cyclone dust collector 12 for further purification. The purified fuel gas is transported to subsequent application equipment through the exhaust pipe.

[0038] A catalyst port 11 is provided in the middle of the inclined tube of the U-shaped returner 9, and the catalyst and the reflux particles are fully mixed in the high temperature area to decompose the tar through thermal cracking. A return air distribution plate 10 and a wind cap are arranged at the bottom of the U-shaped returner 9 to ensure fluidization and uniform mixing of the return particles.

[0039] An ash discharge pipe 13 is provided at the bottom of the cyclone dust collector to remove solid particle ash produced during the gasification process and further purify the biomass fuel gas.

[0040] The present invention adds a catalyst to the inclined tube of the U-shaped return feeder, and the catalyst, bed material and biomass raw material are fully mixed in the dense phase area, thereby improving the fluidization state. The biomass and the catalyst are distributed on the top of the bed layer, which is beneficial to prolonging the residence time of tar in the dense phase area, thereby promoting the thermal cracking of the tar.

[0041] The temperature at the connection between the U-shaped returner and the vaporization furnace riser is relatively high. Adding catalyst in the inclined tube of the U-shaped returner is also closer to the thermal cracking temperature, at 750 to 850 degrees. The calorific value of combustible gas is relatively high, which effectively improves the gasification efficiency.

[0042] The biomass gas collected by the cyclone dust collector of the present invention is sent to the boiler for mixed combustion after being cooled by the thermal oil heat exchanger. During operation, there is no tar blockage problem in the gas pipeline, and there is no tar condensation on the pipe wall of the thermal oil heat exchanger and the booster fan blades, thereby reducing maintenance costs.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circulating fluidized bed air gasifier for producing low-tar biomass gas, characterized in that: It includes a gasifier riser, a cyclone separator and a U-shaped return material feeder. The upper outlet of the gasifier riser is connected to the top of the cyclone separator, the bottom of the cyclone separator is connected to the U-shaped return material feeder through a vertical pipe, the outlet return material inclined pipe of the U-shaped return material feeder is communicated with the lower part of the gasifier riser, a catalyst port is provided in the middle of the outlet return material inclined pipe of the U-shaped return material feeder, the upper outlet of the cyclone separator is connected to a cyclone dust collector, and an ash discharge pipe is provided at the bottom of the cyclone dust collector.

2. The low-tar biomass gas production device of a circulating fluidized bed air gasifier according to claim 1, characterized in that: The side wall of the gasifier riser is provided with two-stage feed inlets and bed material inlets.

3. The low-tar biomass gas production device using a circulating fluidized bed air gasifier according to claim 1, characterized in that: An air distribution plate and an air hood are provided at the bottom of the gasifier riser, and a slag discharge pipe is provided at the bottom of the gasifier riser.

4. The device for producing low-tar biomass gas using a circulating fluidized bed air gasifier according to claim 3, characterized in that: The combustion chamber is disposed below the air distribution plate, and a gasification air inlet and an ignition oil gun are disposed on the side wall of the combustion chamber.

5. The device for producing low-tar biomass gas using a circulating fluidized bed air gasifier according to claim 4, characterized in that: The combustion chamber adopts an under-bed ignition method to maintain a high-temperature environment for the gasification reaction.

6. The device for producing low-tar biomass gas using a circulating fluidized bed air gasifier according to claim 1, characterized in that: A return material air distribution plate and an air hood are provided at the bottom of the U-shaped return material device.

7. The device for producing low-tar biomass gas using a circulating fluidized bed air gasifier according to claim 1, characterized in that: The catalyst is a natural ore catalyst, including dolomite or olivine.

8. The device for producing low-tar biomass gas using a circulating fluidized bed air gasifier according to claim 1, characterized in that: The catalyst is added through the catalyst port to participate in the tar thermal cracking reaction.

9. The device for producing low-tar biomass gas using a circulating fluidized bed air gasifier according to claim 1, characterized in that: The cyclone separator is used to separate the biomass gas from solid particles, and the solid particles flow back to the U-shaped return feeder.

10. The method for using the circulating fluidized bed air gasification furnace low-tar biomass gas production device according to claim 1, characterized in that: The steps include: The biomass raw material is fed into the gasifier riser and enters the fluidized state together with the bed material; The gasified biomass gas and solid particles enter the cyclone separator. After separation, the particles flow back to the U-shaped return feeder through the vertical pipe. The gas enters the cyclone dust collector for further purification. The purified gas is transported to subsequent application equipment through the exhaust pipe. A catalyst port is provided in the middle of the inclined tube of the U-shaped returner, and the catalyst and the reflux particles are fully mixed in the high temperature area to decompose the tar through thermal cracking. The ash discharge pipe at the bottom of the cyclone dust collector removes the solid particle ash produced during the gasification process and further purifies the biomass gas.

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