A high-efficiency downdraft biomass gasification device

Abstract

The present invention relates to the technical field of gasifiers, and in particular to a high-efficiency downdraft biomass gasification device, wherein the furnace core includes a gasification reactor and a feed barrel, and a first cavity is provided between the feed barrel and the gasification reactor. After the material enters the feed barrel, it is dried and cracked in the feed barrel, and the material and the gasifying agent in the oxidation zone are fully mixed to generate oxidation combustion and high temperature. The temperature of the first cavity rises accordingly, thereby performing high-temperature drying and cracking on the surrounding of the feed barrel. The discharge opening at the bottom of the feed barrel extends to the oxidation zone, and the combustion high temperature directly enters the feed barrel, directly drying and cracking the biomass, thereby improving the drying and cracking efficiency. The air inlet of the present invention is arranged above the oxidation zone, and there is sufficient gasifying agent in the first cavity. The feed barrel extends to the oxidation zone, and the biomass raw material falls in an arc shape, and the biomass is fully and evenly mixed with the gasifying agent during the falling process. The gas inlet of the present invention is arranged between the reduction zone and the charcoal slag zone, and the gas enters the gas pipeline after being filtered through the charcoal slag layer.

Description

Technical Field

[0001] The invention relates to the technical field of gasifiers, and in particular to a high-efficiency downdraft biomass gasification device. Background Art

[0002] my country is a large agricultural country with sufficient biomass energy such as firewood and straw. In the development and utilization of biomass energy, the commonly used methods are direct combustion or gasification power generation. However, when direct combustion is used, firewood needs to be added to the stove frequently, which is inconvenient to use. Gasification power generation is limited by cost and poor economic benefits, and cannot be promoted and applied on a large scale. Traditional stoves have a long history of using firewood and straw. Traditional stoves are inconvenient to use and have low calorific value utilization, generally only 14% to 20%, which causes great air pollution. They are gradually abandoned in rural areas, resulting in less and less development and utilization of biomass energy, and the inability to effectively utilize a large amount of renewable firewood and straw in rural areas. For this reason, biomass gasifiers that gasify biomass such as firewood and straw into combustible gas came into being.

[0003] Biomass gasification is a process that uses biomass as raw material, oxygen (air, oxygen-rich gas or pure oxygen, etc.), water vapor and other gases as gasifying agents, and converts the combustible substances in biomass into combustible gases through thermochemical reactions under high temperature conditions. The main components of the combustible gases produced by biomass gasification are CO, H2, CH4, etc., and there are also a certain amount of by-products such as tar and coke. The type of biomass gasifier is divided into updraft gasifier and downdraft gasifier according to the flow direction of the combustible gas. The disadvantage of the updraft gasifier is the high tar content, which leads to the blockage of the gasifier gas pipeline and the low calorific value of the gas production. The downdraft gasifier requires the combustible gas to pass through the high-temperature oxidation zone and reduction zone, which is conducive to the further cracking of the tar. The tar content in the gas is significantly reduced when the gas is filtered through a part of the carbon slag layer.

[0004] Studies have shown that the specific amount and biomass moisture content are the main factors affecting the production of combustible gas. The specific amount refers to the ratio of the amount of air actually consumed by a unit mass of biomass during the gasification process to the amount of air required for its complete combustion. The specific amount is controlled in a certain range. Before the specific amount reaches the optimal value, the larger the specific amount, the greater the gas production, the greater the content of CO and H2 in the combustible gas, and the calorific value continues to rise. How to improve the specific amount is the main problem of downdraft gasifiers. The main influence of biomass moisture content is that after the biomass enters the gasifier, the free water and bound water in the biomass will evaporate in the drying zone. This process consumes a lot of heat. If the water content of the biomass is too high, the reaction temperature in the gasifier will inevitably decrease, resulting in insufficient reaction in each reaction zone, reducing the quality and output of the combustible gas.

[0005] There are three main types of downdraft gasifiers in the prior art: Figure 1As shown, it is a structural schematic diagram of a downdraft gasifier in the prior art. Figure 1 (a) is an open-type gasifier, which is characterized by the fact that biomass and air enter the gasifier from the top, and air is mainly drawn by the induced draft fan. The gasifier is in a negative pressure state, the gasification intensity is not enough, and the reaction is often not sufficient. Therefore, open-type gasifiers are rarely used on the market. Figure 1 (b) The straight tube gasifier and Figure 1 The throat-type gasifier shown in (c) is one of the two types of gasifiers used on the market. Biomass is fed from the top, and an air inlet is provided on the side of the oxidation zone of the furnace body. Air enters from the side and mixes with the biomass in the oxidation zone to undergo oxidation reaction. The common disadvantage of these two types of furnaces is that since the entire gasifier is filled with biomass raw materials, although multiple air inlets are provided on the side of the oxidation zone of the gasifier, the air entering the air inlet still cannot be fully mixed with the biomass raw materials. When the specific amount is low, the gasification intensity and efficiency are low.

[0006] There is a common problem in the downdraft gasifiers of the prior art: downdraft gasifiers are all provided with grates, which are the main device of the gasifier, and the combustible gas outlet is provided at the bottom of the grate. The tar of the combustible gas is filtered through the carbon layer on the grate and then discharged through the exhaust port. The common disadvantages of the grate structure are: 1. The grate is prone to ash slag coking, and the slag discharge is not smooth, which affects production. 2. The grate is easy to be damaged due to high temperature, and the failure rate is high. A large amount of carbon slag is accumulated on the top of the grate, and the grate is coked, which makes it difficult to discharge carbon slag. Summary of the invention

[0007] The purpose of the present invention is to provide a high-efficiency downdraft biomass gasification device in view of the deficiencies of the prior art, which solves the problems raised by the background technology. The first cavity gasification agent and the dried and cracked biomass raw materials are fully mixed and burned to generate high temperature. The high temperature generated by the combustion passes through the first cavity to quickly heat up the outer wall of the feed barrel, and the biomass raw materials in the feed barrel are dried and the pyrolysis reaction is accelerated, thereby improving the gasification efficiency and gasification intensity.

[0008] The technical solution adopted by the present invention to solve its technical problems is: a high-efficiency downdraft biomass gasification device, comprising a furnace body and a furnace core, the furnace core is arranged inside the furnace body, and the furnace core is provided with a drying zone, a pyrolysis zone, an oxidation zone and a reduction layer from top to bottom, the furnace core comprises a gasification generator and a feed barrel, the feed barrel is connected with the feed device, the feed barrel is arranged inside the gasification generator, the feed barrel is a hollow structure with an opening at the lower end, the upper end of the feed barrel is fixed to the furnace top, the lower end of the feed barrel extends to the oxidation zone, the drying zone and the pyrolysis zone are arranged inside the feed barrel, a first cavity is arranged between the outer wall of the feed barrel and the inner wall of the gasification generator, and the furnace core is provided with an air inlet, and the air inlet is arranged above the oxidation zone.

[0009] Preferably, the gasification generator and the inner wall of the furnace body are provided with a second cavity, the second cavity is provided with a gas pipeline, and the gas inlet is arranged below the reduction zone.

[0010] Preferably, the second cavity is a cooling cavity, the flue gas pipeline runs through the cooling cavity, and the flue gas outlet is arranged at the upper part of the furnace body.

[0011] Preferably, a carbon slag area is provided at the lower part of the furnace body, a carbon outlet is provided at the bottom, the carbon slag area is connected with the reduction area, and the carbon slag area is in an inverted cone shape.

[0012] Preferably, the air inlet is arranged at the top of the furnace core, and the air inlet is connected to a blast device.

[0013] Preferably, the pipeline is arranged on one side of the furnace body, and the gas pipeline is arranged vertically.

[0014] Preferably, the feed barrel is arranged at the center of the gasification generator, and the feed device is arranged at the side of the feed barrel.

[0015] Compared with the prior art, the high-efficiency downdraft biomass gasification device of the present invention has the following beneficial effects:

[0016] 1. The furnace core of the present invention includes a gasification generator and a feed barrel. A first cavity is arranged between the feed barrel and the gasification generator. After the material enters the feed barrel, it is dried and cracked in the feed barrel. An oxidation combustion reaction occurs in the oxidation zone. The temperature of the first cavity rises accordingly, thereby preheating the feed barrel. The lower part of the feed barrel is open and extends to the oxidation zone. The combustion high temperature directly enters the feed barrel, directly dries and cracks the biomass, and improves the drying and cracking efficiency. 2. The air inlet of the present invention is arranged above the oxidation zone. There is sufficient gasification agent in the first cavity. The feed barrel extends to the oxidation zone. The biomass falls in an arc shape. The biomass is fully mixed with the gasification agent during the falling process, and the mixing is more uniform. 3. The gas inlet of the present invention is arranged between the reduction zone and the carbon slag zone. The gas enters the gas pipeline after being filtered through part of the carbon slag layer, and the tar is less. 4. The second cavity of the present invention is a cooling cavity. The gas passes through the second cavity through a pipeline and is discharged from the upper part of the furnace body to cool the gas. The gas is separated from the tar. The tar falls along the gas pipeline to the carbon slag zone for further pyrolysis. 5. The second cavity of the present invention is a cooling cavity, and the furnace body is cooled by the cooling cavity, thereby reducing the temperature of the furnace body and improving the safety of the gasification furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a downdraft gasifier in the prior art.

[0018] Figure 2 It is a structural schematic diagram of the present invention.

[0019] Figure 3 It is a structural schematic diagram of the present invention.

[0020] Description of reference numerals:

[0021] 1 - furnace body, 2 - furnace core, 3 - gasification generator, 4 - feed barrel, 5 - feed device, 6 - air inlet, 7 - gas pipeline, 8 - gas inlet, 9 - gas outlet, 10 - drying zone, 11 - pyrolysis zone, 12 - oxidation zone, 13 - reduction zone, 14 - charcoal slag zone, 15 - charcoal outlet, 16 - first cavity, 17 - second cavity. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the implementation scope of the present invention is not limited thereto.

[0023] like Figure 2 and Figure 3 As shown, a high-efficiency downdraft biomass gasification device of this embodiment includes a furnace body 1 and a furnace core 2, the furnace core 2 is arranged inside the furnace body 1, and the furnace core 2 is provided with a drying zone 10, a pyrolysis zone 11, an oxidation zone 12 and a reduction layer 13 from top to bottom, and a carbon slag zone 14 is arranged below the reduction zone 13, and the carbon slag zone 14 is connected to the reduction zone 13, and a carbon outlet 15 is arranged at the bottom of the carbon slag zone 14;

[0024] The furnace core 2 includes a gasifier 3 and a feed barrel 4. The feed barrel 4 is arranged at the center of the gasifier 3. The feed barrel 3 is a hollow structure with an opening at the lower end. The upper end of the feed barrel 4 is fixed to the furnace top. The lower end of the feed barrel 4 extends to the oxidation zone 12. The feed barrel 4 is connected to a feed device 5. The feed device 5 is arranged on the side of the feed barrel 4. The drying zone 10 and the pyrolysis zone 11 are arranged inside the feed barrel 4. A first cavity 16 is arranged between the outer wall of the feed barrel 4 and the inner wall of the gasifier 3. The furnace core 2 is provided with an air inlet 6. The air inlet 6 is arranged above the oxidation zone 12. The air inlet 6 is connected to the blower and the air supply pipeline.

[0025] There is a gap between the furnace body 1 and the furnace core 2, forming a second cavity 17, the second cavity 17 is a cooling cavity, the cooling medium of the second cavity 17 is cooling water, a gas pipeline 7 is arranged in the second cavity 17, the gas pipeline 7 is arranged vertically, and passes through the second cavity 17, the gas outlet 9 of the gas pipeline 7 is arranged at the upper part of the furnace body 1, and the gas inlet 8 is arranged below the reduction zone 13;

[0026] Furthermore, the furnace body 1 includes an upper cylindrical section and a lower inverted cone section, the charcoal slag area 14 is arranged in the inverted cone section, and the charcoal outlet 15 is arranged at the bottom, and the inverted cone section is convenient for slag discharge.

[0027] Furthermore, the air inlet 6 is arranged at the top of the furnace core 2, and the air is blown downward from the top through the blowing device. Under the action of the air pressure of the blowing device, the air flow moves downward, and the air flow with a certain air pressure is mixed with the biomass more evenly.

[0028] Furthermore, the outer wall of the furnace core 2 is provided with a refractory layer.

[0029] The furnace core 2 of the present invention includes a gasification generator 3 and a feed barrel 4. A first cavity 16 is provided between the feed barrel 4 and the gasification generator 3. After the biomass enters the feed barrel 4, it is dried and cracked in the feed barrel 4. An oxidation reaction occurs in the oxidation zone 12. The temperature of the first cavity 16 rises accordingly, thereby preheating the surroundings of the feed barrel 4. The lower part of the feed barrel 4 is open and extends to the oxidation zone. The combustion high temperature directly enters the feed barrel 4, directly dries and cracks the biomass, and improves the drying and cracking efficiency compared with the prior art. Figure 1 (b) The straight tube gasifier and Figure 1 The average temperature of the drying zone E of the throat gasifier shown in (c) is 30-80°, the temperature of the cracking zone F is 100-200°, the temperature of the drying zone of the present invention is (80-200), and the temperature of the cracking zone 11 of the present invention is (200-300).

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A high-efficiency downdraft biomass gasification device, characterized in that: The invention comprises a furnace body and a furnace core, wherein the furnace core is arranged inside the furnace body, and a drying zone, a pyrolysis zone, an oxidation zone and a reduction zone are arranged on the furnace core from top to bottom, the furnace core comprises a gasifier and a feed barrel, the feed barrel is connected with a feed device, the feed barrel is arranged inside the gasifier, the feed barrel is a hollow structure with an opening at the lower end, the upper end of the feed barrel is fixed to the furnace top, the lower end of the feed barrel extends to the oxidation zone, the drying zone and the pyrolysis zone are arranged inside the feed barrel, a first cavity is arranged between the outer wall of the feed barrel and the inner wall of the gasifier, the furnace core is provided with an air inlet, and the air inlet is arranged above the oxidation zone; a second cavity is arranged between the gasifier and the inner wall of the furnace body, a gas pipeline is arranged in the second cavity, and the gas inlet is arranged below the reduction zone; the second cavity is a cooling cavity, the gas pipeline runs through the cooling cavity, and the gas outlet is arranged at the upper part of the furnace body.

2. The high-efficiency downdraft biomass gasification device according to claim 1, characterized in that: The gas pipeline is arranged on one side of the furnace body, and the gas pipeline is arranged vertically.

3. The high-efficiency downdraft biomass gasification device according to claim 1, characterized in that: A carbon slag area is arranged at the lower part of the furnace body, and a carbon outlet is arranged at the bottom. The carbon slag area is connected with the reduction area, and the carbon slag area is in an inverted cone shape.

4. The high-efficiency downdraft biomass gasification device according to claim 1, characterized in that: The air inlet is connected to the air blowing device.

5. The high-efficiency downdraft biomass gasification device according to claim 1, characterized in that: The feed barrel is arranged at the upper center position of the gasification generator, and the feed device is arranged at the side of the feed barrel.

Images