A biomass gasifier

Abstract

The present invention provides a biomass gasifier, comprising: a gasifier furnace body, an outer tube, and an ash receiving trough, wherein the outer tube is sleeved on the lower part of the gasifier furnace body, and a gasification gas channel is formed between the outer tube and the furnace body; a support body is fixedly arranged at the bottom of the ash receiving trough, and a grate is arranged on the support body; water is contained in the ash receiving trough, and a part of the support body and the outer tube are immersed in the water; the raw fuel gas generated by the reaction of the gasifier enters the carbon layer and reacts with the carbon slag to generate gasification gas, which enters the gasification gas channel from the gap between the grate and the furnace body, and then is discharged from the gas outlet arranged on the outer tube. The present invention has many advantages such as simple structure, convenient use, low cost, and high gasification efficiency.

Description

[0001] The invention belongs to the technical field of biomass energy, and in particular relates to a novel downdraft gas biomass furnace. Background Art

[0002] Biomass fuel is a clean and renewable energy source, ranking fourth in the world's total energy consumption after coal, oil and natural gas. The main ways to utilize biomass fuel are combustion, thermochemical conversion and biochemical conversion. Biomass gasification technology has high energy conversion efficiency, simple equipment and low investment, and is one of the ways to thermochemically convert biomass. The gas produced by biomass gasification can be used as synthesis gas for indirect liquefaction to produce liquid fuels such as methanol and dimethyl ether, or directly used as boiler fuel or power generation to generate heat or generate electricity. At present, the main biomass gasification technologies are fluidized bed gasification and fixed bed gasification technology. Commonly used fixed bed gasifiers are mainly of two types: updraft and downdraft. Relatively speaking, the tar content of the synthesis gas produced by the downdraft fixed bed gasifier is lower, but there are still problems such as poor stability of synthesis gas quality and small gasification scale.

[0003] When a downdraft fixed-bed gasifier uses a reciprocating grate, the furnace pressure in the gasifier will fluctuate when the grate is working, affecting the gasification efficiency and stability of the system.

[0004] The gasifier in the CN 104178220B patent uses a tower grate, but there is still a problem of high tar content in the fuel gas. The tower grate extends into the furnace body and there is a gap between the side wall of the furnace body. The tower grate is applied to an updraft gasifier. If the structure is applied to a downdraft gasifier, the airflow in the gasifier can only flow along the gap between the grate and the gasifier, which is not conducive to the airflow passing through the carbon layer uniformly, resulting in insufficient gasification reaction and affecting the overall efficiency of the system. It is necessary to solve the problem of uneven airflow distribution at the grate.

[0005] In the CN 204342744U patent, a combustion tube is added to the furnace body of the gasifier, and the bottom end of the combustion tube is suspended above the grate, and an air distribution duct is arranged in the combustion tube to form a pre-combustion area above the gasifier, and the biomass fuel undergoes a primary gasification reaction in the pre-combustion area. An air vent is arranged at the ash hopper, and the carbon slag remaining from the reaction in the pre-combustion area continues to undergo a secondary gasification reaction in the main combustion area below the gasifier. This type of gasifier has air vents arranged in multiple places, which weakens the formation process of the "reduction layer" in the gasifier, and when the air flow control in the main combustion area and the pre-combustion area is unreasonable, there may be a situation where no "reduction layer" is generated, which ultimately affects the gasification efficiency. In view of this, overcoming the defects of the above-mentioned prior art is a problem to be solved in this field. Summary of the invention

[0006] In order to overcome the technical problems existing in the prior art, the present invention provides a biomass gasifier, comprising: a gasifier body, an outer tube, and an ash receiving trough, wherein the outer tube is sleeved on the lower part of the gasifier body, and a gasification gas channel is formed between the outer tube and the body;

[0007] A support body is fixedly arranged at the bottom of the ash receiving trough, and a grate is arranged on the support body; water is contained in the ash receiving trough, and the lower part of the support body and the outer cylinder is immersed in the water;

[0008] The raw fuel gas generated by the reaction in the gasifier enters the carbon layer and reacts with the carbon slag to generate gasification gas, which enters the gasification gas channel from the gap between the grate and the furnace body and is then discharged from the gas outlet arranged on the outer cylinder.

[0009] Furthermore, it also includes a driving mechanism, which is arranged at the bottom of the ash receiving chute and is used to drive the ash receiving chute to rotate.

[0010] Preferably, a plurality of ash retaining rings are provided on the outer wall of the furnace body of the gasifier and the inner wall of the outer tube located in the gasification gas passage.

[0011] Furthermore, a slag discharge plate is fixedly arranged on the support body, the slag discharge plate is fixedly connected to one end of the support body, and the other end of the slag discharge plate is a free end.

[0012] Preferably, a scraper is provided on the support body near the grate to remove ash and slag that falls onto the grate in the furnace body.

[0013] Furthermore, a number of hoods are fixedly installed on the grate. The hoods are hollow tubes and penetrate the grate. The upper and lower ends of the hoods are respectively located outside the grate. The upper end of the hood has a support rod and a hood head. The support rod and the hood head are fixedly connected in an umbrella shape; the lower end of the hood is in a trumpet shape that is small at the top and large at the bottom.

[0014] Preferably, the grate is in a multi-layer tower shape, and a plurality of hoods are symmetrically arranged on each layer.

[0015] Furthermore, a slag discharge plate is fixedly provided on the outer wall of the outer cylinder, which is used to take out the ash discharged from the slag discharge plate.

[0016] Preferably, the driving mechanism is a pair of meshing bevel gears, driven by a motor.

[0017] Preferably, the ash receiving trough is shaped like a basin with a small bottom and a large mouth.

[0018] Furthermore, it also includes an ash receiving platform, which is fixedly arranged on the inner wall of the gasification furnace body and close to the bottom of the ash scraper.

[0019] Compared with the prior art, the biomass gasifier provided by the present invention has the following advantages:

[0020] (1) A tower-type grate is used, and an outer tube is arranged outside the furnace body. The gasified gas is discharged from the gap between the grate and the gasifier body and then enters the gas outlet on the side wall of the outer tube. This can effectively solve the problem of periodic fluctuation of the system caused by intermittent ash discharge of the grate in the downdraft gasifier, improve the continuity and stability of the system operation, and improve the gasification efficiency.

[0021] (2) Part of the support body is immersed in the water of the ash receiving trough. This is beneficial to reduce the temperature of the support body of the grate system and extend the service life of the grate.

[0022] (3) A slag discharge plate is provided on the outside of the support body, and the ash in the ash receiving trough is pushed to the slag discharge plate through the slag discharge plate to realize the ash discharge operation. The ash discharge device is simple and saves equipment cost.

[0023] (4) The grate is provided with vents for communicating the gas of adjacent grate layers. The protruding top of the vent is provided with a hood, and the bottom of the vent is flared. During the rotation of the support body, the raw gas generated by the reaction of the gasifier flows through the vents, enters the carbon layer, and undergoes a sufficient gasification reaction with the carbon slag, thereby improving the gasification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of devices and methods consistent with the invention and, together with the detailed description, serve to explain advantages and principles consistent with the invention.

[0025] Figure 1 It is a structural schematic diagram of a biomass gasifier according to a preferred embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of the hood;

[0027] Figure 3 This is a top view of the grate;

[0028] Figure 4 is a top view of the support body.

[0029] Description of Reference Numerals

[0030] 1-Gasification furnace body

[0031] 2-Outer cylinder

[0032] 3- Ash trough

[0033] 4-Support

[0034] 5-Grate

[0035] 6- Driving mechanism

[0036] 7-ash retaining ring

[0037] 8-Slag discharge plate

[0038] 9-Hood

[0039] 10- Putty knife

[0040] 11-Slag plate

[0041] 12-Biomass feed port

[0042] 13-Gasifying agent inlet

[0043] 14- Ash support

[0044] 21-Air outlet

[0045] 61, 62-bevel gear DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described below. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other, and the technical concept of the present invention can be implemented in combination with other known technologies or other technologies that are the same as those known technologies.

[0047] Unless otherwise specified, qualifiers such as "first" and "second" appearing in this document do not refer to limitations on time sequence, quantity, or importance, but are merely used to distinguish one technical feature from another in the technical solution. Similarly, modifiers such as "approximately" and "approximately" that appear before a numeral in this document usually include the number itself, and their specific meanings should be understood in conjunction with the context. Similarly, unless it is a noun modified by a specific quantitative quantifier, it should be regarded as including both singular and plural forms in this document, and the technical solution may include both the singular and plural technical features.

[0048] In the description of the above specific embodiments, the use of directional terms such as "up", "down", "left", "right", "top", "bottom", "vertical", "horizontal" and "lateral" are merely for the purpose of convenience of description and should not be regarded as limiting.

[0049] A preferred embodiment of the present invention provides a biomass gasifier, such as Figure 1 As shown, it comprises: a gasifier furnace body 1, an outer tube 2, and an ash receiving trough 3. The outer tube 2 is sleeved on the lower part of the gasifier furnace body 1, and a gasification gas channel is formed between the outer tube 2 and the furnace body 1. A support body 4 is fixedly arranged at the bottom of the ash receiving trough 3, and a grate 5 is arranged on the support body 4; the ash receiving trough 3 contains water, and a part of the support body 4 and the outer tube 2 are immersed in the water; the raw fuel gas generated by the reaction of the gasifier enters the carbon layer and reacts with the carbon slag to generate gasification gas, which enters the gasification gas channel from the gap between the grate and the furnace body, and then is discharged from the gas outlet 21 arranged on the outer tube 2.

[0050] In this embodiment, a driving mechanism 6 is further included, which is arranged at the bottom of the ash receiving trough 3 and is used to drive the ash receiving trough 3 to rotate. Specifically, the driving mechanism 6 is a pair of meshing bevel gears 61 and 62, which are driven by a motor. The bevel gear 61 is arranged horizontally, and the bevel gear 62 is arranged vertically. In this embodiment, the ash receiving trough 3 is shaped like a basin with a small bottom and a large mouth. The ash receiving trough 3 rotates as the bevel gear 61 rotates.

[0051] In this embodiment, a plurality of ash retaining rings 7 are arranged on the outer wall of the gasifier body and the inner wall of the outer tube in the gasification gas passage. The ash retaining rings on the outer wall and the inner wall are arranged alternately. Such an arrangement makes the ash retaining effect more ideal.

[0052] Preferably, a scraper 10 is provided on the support body 4 near the grate 5 to remove ash and slag that falls onto the grate in the furnace body.

[0053] like Figure 2 , Figure 3 As shown, eight hoods 9 are fixedly arranged on the grate 5. The hoods 9 are in the shape of hollow tubes. The hoods 9 penetrate the grate 5, and their upper and lower ends are respectively located outside the grate 5. The upper ends of the hoods 9 have support rods 91 and hood heads 92, and the support rods 91 and hood heads 92 are fixedly connected to form an umbrella shape; the lower ends of the hoods 9 are in the shape of a trumpet that is small at the top and large at the bottom.

[0054] In this embodiment, the grate 5 is in a multi-layer tower shape, composed of a plurality of single conical grates, and a plurality of conical hoods 9 are symmetrically arranged on each layer.

[0055] like Figure 4 As shown, a slag plate 11 is fixedly provided on the outer wall of the outer tube 2 for removing the ash discharged from the slag plate 8. Specifically, a slag plate 8 is fixedly provided on the support body 4, and the slag plate 8 is fixedly connected to one end of the support body 4, and the other end of the slag plate 8 is a free end.

[0056] The biomass gasifier of the present invention further comprises an ash receiving platform 14 , which is fixedly arranged on the inner wall of the gasifier body 1 and close to the bottom of the ash scraper 10 .

[0057] The present invention is implemented through the following technical solution: the raw biomass and the gasifying agent are introduced from the biomass feed port 12 and the gasifying agent inlet 13 respectively.

[0058] The working principle of the downdraft gasifier is that the biomass raw material is added from the top of the gasifier, gradually moves to the bottom by gravity, and the ash is finally discharged from the bottom. The gasifier is added at the top of the gasifier, and the generated gasification gas is precipitated from the bottom. The raw material undergoes volatile pyrolysis from top to bottom, incomplete combustion of volatile substances and carbon, and secondary cracking of some large molecular volatile substances. Carbon dioxide and water vapor undergo reduction reaction with carbon in the remaining carbon layer, and finally a mixed gas containing carbon monoxide, hydrogen, methane, carbon dioxide and nitrogen is obtained, namely gasification gas.

[0059] The carbon slag produced by the reaction falls and deposits on the grate 5 to form a carbon layer of a certain height. The raw fuel gas produced by the reaction in the gasifier flows through the vent into the carbon layer to react with the carbon slag to produce gasification gas and ash slag. The gasification gas is discharged from the gap between the grate 11 and the gasifier body 2 and enters the outer cylinder 10, and then passes through the ash retaining ring 4 and is discharged from the gas outlet 9. The ash slag that falls to the grate and the ash support platform due to gravity enters the ash receiving trough 6 from the gasifier through the ash scraper and is sent out through the slag discharge plate 12.

[0060] The conical hood head 92 can prevent carbon residue from falling directly into the vent hole inside the tubular body, thereby preventing the vent hole from being blocked. The number of hood support rods 91 is 2 or 4. The number is not limited, and in principle, it is not less than 2.

[0061] During the rotation of the support body 4, the raw fuel gas produced by the reaction of the gasifier flows through the grate vents 17, and undergoes a sufficient gasification reaction with the carbon slag in the carbon layer. When the grate 5 and the scraper 10 rotate together, the ash and slag accumulated on the grate 5 and the ash support platform 13 are continuously discharged to the ash receiving trough 3. During operation, the driving mechanism 6 drives the ash receiving trough 3, the grate 5, the support body 4 and the slag discharge plate 8 to rotate around the gasifier furnace body 1 through the gear 61. The ash and slag in the ash receiving trough 3 is pushed to the slag discharge plate 11 through the slag discharge plate 8 to realize the ash discharge operation. The bottom end of the outer tube 2 is suspended and is located below the bottom of the gasifier furnace body 1. A water seal is formed between the bottom of the outer tube 2 and the ash receiving trough 3 to achieve a system sealing effect.

[0062] Compared with the prior art, the biomass gasifier provided by the present invention has the following advantages: Compared with the prior art, the biomass gasifier provided by the present invention has the following advantages:

[0063] (1) A tower-type grate is used, and an outer tube is arranged outside the furnace body. The gasified gas is discharged from the gap between the grate and the gasifier body and then enters the gas outlet on the side wall of the outer tube. This can effectively solve the problem of periodic fluctuation of the system caused by intermittent ash discharge of the grate in the downdraft gasifier, improve the continuity and stability of the system operation, and improve the gasification efficiency.

[0064] (2) Part of the support body is immersed in the water of the ash receiving trough. This is beneficial to reduce the temperature of the support body of the grate system and extend the service life of the grate.

[0065] (3) A slag discharge plate is provided on the outside of the support body, and the ash in the ash receiving trough is pushed to the slag discharge plate through the slag discharge plate to realize the ash discharge operation. The ash discharge device is simple and saves equipment cost.

[0066] (4) The grate is provided with vents for communicating the gas of adjacent grate layers. The protruding top of the vent is provided with a hood, and the bottom of the vent is flared. During the rotation of the support body, the raw gas generated by the reaction of the gasifier flows through the vents, enters the carbon layer, and undergoes a sufficient gasification reaction with the carbon slag, thereby improving the gasification efficiency.

[0067] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A biomass gasifier, characterized in that: include: A gasifier body, an outer tube, and an ash receiving trough, wherein the outer tube is sleeved on the lower part of the gasifier body, and a gasification gas channel is formed between the outer tube and the body; A support body is fixedly arranged at the bottom of the ash receiving trough, and a grate is arranged on the support body; the ash receiving trough is filled with water, and the support body and the lower part of the outer cylinder are immersed in the water; The raw fuel gas generated by the reaction in the gasifier enters the carbon layer and reacts with the carbon slag to generate gasification gas, which enters the gasification gas channel from the gap between the grate and the furnace body and is then discharged from the gas outlet provided on the outer cylinder; A plurality of hoods are fixedly arranged on the grate. The hoods are hollow tubes. The hoods penetrate the grate. The upper and lower ends of the hoods are respectively located outside the grate. The upper end of the hood has a support rod and a hood head. The support rod and the hood head are fixedly connected in an umbrella shape. The lower end of the hood is in a trumpet shape with a small top and a large bottom. The grate is in the shape of a multi-layer tower, and a number of wind caps are symmetrically arranged on each layer; It also includes a driving mechanism, which is arranged at the bottom of the ash receiving trough and is used to drive the ash receiving trough to rotate.

2. The biomass gasifier according to claim 1, characterized in that: A plurality of ash retaining rings are arranged on the outer wall of the gasifier furnace body and the inner wall of the outer tube located in the gasification gas passage.

3. The biomass gasifier according to claim 1, characterized in that: A slag discharge plate is fixedly arranged on the support body, the slag discharge plate is fixedly connected to one end of the support body, and the other end of the slag discharge plate is a free end.

4. The biomass gasifier according to claim 1, characterized in that: A scraper is also provided on the support body near the grate to remove the ash and slag that falls onto the grate in the furnace body.

5. The biomass gasifier according to claim 1, characterized in that: The driving mechanism is a pair of meshing bevel gears and is driven by a motor.

6. The biomass gasifier according to claim 1, characterized in that: The ash receiving trough is in the shape of a basin with a small bottom and a large mouth.

7. The biomass gasifier according to claim 4, characterized in that: It also includes an ash receiving platform, which is fixedly arranged on the inner wall of the gasification furnace body and close to the bottom of the scraper.

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