Fluidized bed gasifier distributor plate, fluidized bed gasifier and method for gasifying biomass

Abstract

The application discloses a fluidized bed gasification furnace distribution plate, a fluidized bed gasification furnace and a biomass gasification method, wherein the fluidized bed gasification furnace distribution plate comprises a distribution plate, a plurality of fluidizing agent ports, first gasification agent ports and a slag discharge port are arranged on the distribution plate, and the pore diameter of the first gasification agent ports is larger than that of the fluidizing agent ports; the fluidizing agent ports are arranged on the side of the distribution plate, and the first gasification agent ports are arranged around the slag discharge port, so that the reaction temperature is improved, a high-temperature central region is formed, tar is eliminated, the range of the high-temperature central region of the gasification furnace is enlarged, and the problem that the high-temperature central region is prone to slagging is reduced while the tar is eliminated.

Description

Technical Field

[0001] This invention relates to a fluidized bed gasifier distribution plate, a fluidized bed gasifier, and a biomass gasification method. Background Technology

[0002] Biomass, as a green feedstock, can be converted into syngas rich in H2, CO, and CH4 at high temperatures using gasification technology, thus transforming biomass into an important green industrial gas. Combined with mature downstream processes such as purification, conversion, Fischer-Tropsch synthesis, methanol synthesis, and ammonia synthesis, numerous application scenarios can be derived. This makes biomass, a green feedstock, a promising candidate for industrial gas synthesis.

[0003] As the primary step in biomass gasification, efficient and stable syngas production is crucial. While coal gasification technology is relatively mature, when fixed-bed and fluidized-flow coal gasification technologies are directly applied to biomass gasification, the high activity and organic fiber content of biomass make it difficult to obtain suitable feedstocks for fixed-bed and fluidized-flow gasification during the feedstock preparation processes (pelletizing, slurrying, and pulverizing). Therefore, fluidized-flow gasification, with its advantages of granular feedstock and moderate gasification temperature, is highly suitable for biomass gasification applications.

[0004] In the experimental and technological applications of fluidized bed gasification of biomass, based on the compositional characteristics (industrial analysis and elemental analysis) of biomass, it has a high oxygen content and a calorific value far lower than coal; high K and Na content and a low ash melting point. Excessive gasification furnace temperature can lead to slagging inside the furnace, affecting solid ash discharge, and also causing increased local wear and blockage of the ash discharge channel. Conversely, excessively low gasification furnace operating temperature can prevent the complete conversion of biomass gasification tar into syngas. Furthermore, because the ash particles produced by biomass gasification are small, they easily clog the internal components of the fluidized bed, and fine ash can backflow into the gas inlet pipes and equipment, affecting the normal operation of the gasifier and increasing the workload for production maintenance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that existing biomass fluidized bed gasifiers have high tar content, low ash melting point, easy slagging, and a lot of fine ash powder that is easy to reverse the flow of the distribution plate. The present invention provides a fluidized bed gasifier distribution plate, a fluidized bed gasifier, and a biomass gasification method. The fluidized bed gasifier of the present invention has low tar content in the syngas, is not easy to slagging, and the distribution plate has a long stable operating time.

[0006] The present invention introduces the gasifying agent from the bottom of the distribution plate and the fluidizing agent from the side of the distribution plate, which can increase the reaction temperature, form a central high-temperature zone, and eliminate tar. However, introducing the gasifying agent from the slag discharge port can lead to slagging in the central high-temperature zone and poor solid slag discharge. Therefore, by setting gasifying agent ports around the slag discharge port, the range of the central high-temperature zone of the gasifier is expanded, reducing the problem of slagging in the central high-temperature zone while eliminating tar. Furthermore, by setting a leak-proof component at the fluidizing agent port on the side of the distribution plate, the operational risk caused by backflow of fine powder from the fluidizing agent port is solved.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] This invention proposes a distribution plate for a fluidized bed gasifier, wherein the distribution plate is provided with a plurality of fluidizing agent ports, a first gasifying agent port and a slag discharge port, wherein the aperture of the first gasifying agent port is larger than the aperture of the fluidizing agent port;

[0009] The distribution plate is cone-shaped, the fluidizing agent inlet is located on the side of the distribution plate, and the slag discharge port is located at the bottom of the distribution plate; the first gasifying agent inlet is located around the slag discharge port and is closer to the slag discharge port than the fluidizing agent inlet; at least a portion of the axis of the fluidizing agent inlet is inclined toward one end of the slag discharge port.

[0010] In this invention, it is understood that the axis of the remaining portion of the fluidizing agent inlet can be inclined towards one end of the slag discharge port, or towards one end away from the slag discharge port, or along a horizontal direction. Preferably, the axis of the remaining portion of the fluidizing agent inlet is inclined towards one end away from the slag discharge port or along a horizontal direction; furthermore, the chord length L2 of the region formed by all the fluidizing agent inlets inclined towards one end of the slag discharge port is L1~10L1, where L1 is the diameter of the feed inlet of the fluidized bed gasifier. If the width of the feed acceleration zone is too narrow, it cannot be guaranteed that all feed can be accelerated; if it is too wide, it not only accelerates the feed but also accelerates the addition of peripheral ash and slag into the central high-temperature zone, competing for the gasifying agent, resulting in incomplete gasification.

[0011] The distribution plate is divided into a feed acceleration zone and a bed fluidization zone along its circumference. All the fluidizing agent ports that are inclined toward the end of the slag discharge port are located in the feed acceleration zone, and the chord length of the feed acceleration zone is L2. The remaining fluidizing agent ports are located in the bed fluidization zone.

[0012] Furthermore, the remaining portion of the fluidizing agent inlet has an inclination angle A3 of 0~45° relative to the horizontal plane, for example 0°. The inclination angle A3 refers to the angle between the axis of the fluidizing agent inlet and the horizontal plane, and the positive angle refers to the horizontal upward.

[0013] In this invention, the inclination angle A2 of the fluidizing agent port, which is inclined toward one end of the slag discharge port, relative to the horizontal plane is preferably -30~0°, and does not include 0°, for example -15°. The inclination angle A2 refers to the angle between the axis of the fluidizing agent port and the horizontal plane.

[0014] In this invention, a plurality of fluidizing agent outlets are uniformly distributed on the distribution plate.

[0015] The number and distribution of fluidizing agent ports are optimized according to the scale of gasification feed. Generally, 5 to 10 layers of fluidizing agent ports are distributed sequentially from the top to the bottom of the distribution plate. Each layer includes multiple fluidizing agent ports that are evenly distributed along the circumference of the distribution plate. The spacing between two adjacent layers of fluidizing agent ports along the axial direction of the distribution plate is preferably 100 to 300 mm.

[0016] In this invention, preferably, the axis of the first gasifying agent inlet is parallel to the central axis of the distribution plate. The gasifying agent is ejected from the first gasifying agent inlet, driving high-speed turbulence in the bubbling fluidized bed region, thereby enhancing the mass transfer, heat transfer, and high-temperature reaction processes in the central region and the upper bubbling fluidized bed region.

[0017] In this invention, the diameter of the first gasifying agent inlet is preferably 10-200 mm, for example 80 mm.

[0018] In this invention, the orifice diameter of the fluidizing agent port is preferably 2-10 mm, for example 5 mm.

[0019] In this invention, preferably, multiple first gasifying agent ports are evenly distributed along the circumference of the slag discharge port, for example, three ports.

[0020] In this invention, the distance between the axis of the first gasifying agent port and the axis of the slag discharge port is preferably 200-500 mm, for example, 300 mm. If the distance is too small, the gas ejected from the first gasifying agent port will obstruct the descending ash from entering the slag discharge port, resulting in poor slag discharge; if the distance is too large, unreacted carbonaceous ash will enter the slag discharge port, resulting in excessively high carbon content in the discharged slag and wasting raw materials.

[0021] In this invention, the inclination angle A4 of the cone surface of the distribution plate relative to the horizontal plane is preferably 30~80°, for example 45° or 60°, and the inclination angle A4 refers to the angle between the cone surface of the distribution plate and the horizontal plane.

[0022] In this invention, the fluidizing agent inlet is used to introduce the fluidizing agent, and the first gasifying agent inlet is used to introduce the gasifying agent.

[0023] In this invention, the distribution plate is made of metal and / or non-metallic refractory materials.

[0024] In this invention, a leak-proof component is preferably provided on the fluidizing agent inlet to prevent ash and slag from flowing back to the outside of the distribution plate. The leak-proof component preferably includes a connecting portion and a leak-proof portion. One end of the connecting portion is connected to the leak-proof portion, and the outer diameter of the other end of the connecting portion matches the aperture of the fluidizing agent inlet. The leak-proof portion is provided with a porous structure for the fluidizing agent to pass through, and the pore size of the porous structure is 0.1~500μm. The connecting portion is provided with a perforated structure for the fluidizing agent to pass through. The porous structure only allows the gasifying agent to pass through, making it difficult for ash and slag to pass through, thereby preventing ash and slag from flowing back to the outside of the distribution plate. The leak-proof component is connected to the fluidizing agent inlet by inserting the other end of the connecting portion into the fluidizing agent inlet.

[0025] Preferably, the leak-proof part is a block, and the block is provided with the porous structure. The block is made of one or more of the following: metal wire mesh, metal fiber, metal powder and ceramic.

[0026] Preferably, the pore size of the porous structure is 0.1~120μm, for example 5~25μm. If the pore size of the porous structure is too large, ash and slag will clog the porous structure; if it is too small, it will affect the fluidization effect of the fluidizing agent.

[0027] The hole structure on the connecting part can be conventional in the art, such as through holes or mesh holes.

[0028] Preferably, the connecting part includes a first support and a sleeve. The first support has a support groove, and the bottom of the support groove has a first through hole. The leak-proof part is disposed in the support groove. One end of the sleeve has a flange, the outer diameter of which is larger than the diameter of the fluidizing agent inlet and smaller than the inner diameter of the support groove. The flange is located within the support groove. The outer diameter of the other end of the sleeve matches the diameter of the fluidizing agent inlet. In this preferred embodiment, the first through hole and the tube hole of the sleeve form a hole structure for the fluidizing agent to pass through. When the leak-proof component is assembled in the fluidizing agent inlet, the other end of the sleeve is inserted into the fluidizing agent inlet, the flange is engaged with the outer periphery of the fluidizing agent inlet, and the gasifying agent enters the furnace body through the second through hole, the porous structure in the leak-proof part, and the first through hole.

[0029] More preferably, the connecting part further includes a second support, which is a sleeve structure. The second support is sleeved on the outside of the flange, and the first support is threaded to the outside of the second support. During installation, the end of the second support can be fixed to the back of the distribution plate by welding, and the first support is threaded to the second support, which facilitates the disassembly and assembly of the leak-proof component.

[0030] More preferably, the leak-proof assembly further includes a first support member and a second support member, wherein the first support member, the leak-proof part, and the second support member are sequentially arranged from top to bottom in the support groove, and both the first support member and the second support member are metal mesh structures. The aperture of the metal mesh structure is preferably 0.1~1mm. The first support member and the second support member prevent the leak-proof part from deforming due to compression.

[0031] The present invention also proposes a fluidized bed gasifier, which includes a gasifier and a distribution plate disposed at the bottom of the gasifier, wherein the distribution plate is the aforementioned fluidized bed gasifier distribution plate.

[0032] It is understood that when the distribution plate of the present invention is installed in the fluidized bed gasifier, the distribution plate is placed in an inverted cone shape at the bottom of the fluidized bed gasifier, that is, the end with the larger diameter of the distribution plate faces upward and the end with the smaller diameter of the distribution plate faces downward.

[0033] It is understood that the gasifier is typically provided with a feed inlet, which is located above the distribution plate, in accordance with the conventions of the art.

[0034] Preferably, the axis of the feed inlet is inclined towards one end of the slag discharge port, and the fluidizing agent inlet is located directly below the feed inlet. The material is initially accelerated through the inclined feed inlet, falls onto the distribution plate, and is further accelerated by the downwardly inclined fluidizing agent below the feed inlet, thereby quickly reaching the central high-temperature zone.

[0035] In this invention, the inclination angle A1 of the feed inlet relative to the horizontal plane is preferably 30~80°, for example 45° or 60°, and the inclination angle A1 is the angle between the axis of the feed inlet and the horizontal plane.

[0036] In this invention, preferably, the inclination angle A1 of the feed inlet relative to the horizontal plane is the same as the inclination angle A4 of the conical surface of the distribution plate relative to the horizontal plane. If the inclination angle of the feed inlet (i.e., A1) is too small, large feed particles will fall parabolically and hit the distribution plate, and most particles will not be able to accelerate to the center. If the inclination angle of the feed inlet (i.e., A1) is too large, the feed particles will aggravate the wear of the distribution plate.

[0037] In this invention, the distance Hf between the lower edge of the feed inlet and the upper edge of the distribution plate is preferably 0~Di, for example 0.48Di or 0.072Di, where Di refers to the inner diameter of the gasifier.

[0038] In this invention, the slag discharge port is preferably further provided with an air inlet pipe, the air inlet pipe forming a second gasifying agent port, and an annular area for slag discharge is provided between the air inlet pipe and the slag discharge port.

[0039] Preferably, the diameter of the second gasifying agent port is 30-70% of the diameter of the slag discharge port. More preferably, the diameter of the second gasifying agent port is 100-200 mm, for example, 150 mm, and the diameter of the slag discharge port is 200-300 mm, for example, 250 mm.

[0040] In this invention, preferably, the axis of the feed inlet intersects the central axis of the gasifier body, such that the feed direction is directly opposite the center direction of the gasifier.

[0041] In this invention, solid biomass enters the gasifier through the feed inlet, and the gasifying agent is divided into two streams (i.e., fluidizing agent and gasifying agent) from the bottom and enters the gasifier. Both undergo combustion and gasification reactions within the gasifier. Simultaneously, due to the fluidization effect of the gas on the solids, a bubbling fluidized state is formed within the furnace body, creating a high-temperature reaction space at the bottom of the furnace body for a certain amount of gas-solid material. Supplementary gasifying agent is injected at high speed from the central region, driving high-speed turbulence in the bubbling fluidized bed region, enhancing mass transfer, heat transfer, and high-temperature reactions in the central region and the upper bubbling fluidized bed region. This results in a central region temperature significantly higher than the fluidized bed gas region temperature, thus forming a central high-temperature zone. The solid biomass is initially accelerated through the downward-sloping feed pipe, falls onto the distribution plate, and is further accelerated by the fluidizing agent, thus quickly reaching the central high-temperature zone. Furthermore, the placement of the first gasifying agent inlet also expands the range of the central high-temperature zone, shortening the distance the biomass particles need to travel to reach it, allowing the biomass to be rapidly gasified in the high-temperature zone while simultaneously eliminating tar.

[0042] The present invention also proposes a biomass gasification method, which uses the aforementioned fluidized bed gasifier. The biomass gasification method includes the following steps: introducing biomass raw materials through the feed inlet, introducing fluidizing agent through the fluidizing agent inlet, and introducing gasifying agent through the first gasifying agent inlet to carry out a gasification reaction.

[0043] In this invention, the fluidizing agent and the gasifying agent are conventional in the art. For example, the fluidizing agent may be oxygen or a mixture of oxygen and steam or a mixture of oxygen, steam and nitrogen or a mixture of oxygen, steam and carbon dioxide, and the gasifying agent may be oxygen or a mixture of oxygen and steam.

[0044] In this invention, the temperature of the gasification reaction is conventional in the art, for example, 890~950℃.

[0045] In this invention, the pressure inside the gasifier is conventional in the art, for example, 2.5 barg.

[0046] In this invention, the D50 particle size of the biomass raw material particles is 1~15mm, for example 6mm.

[0047] In this invention, the biomass raw materials are conventional, such as wood, straw, rice husks, and reeds.

[0048] In this invention, the feed rates of the fluidizing agent and the gasifying agent can be adjusted according to actual working conditions. In some embodiments, the feed rate of the fluidizing agent can be 0.2~2m / s, for example 0.3m / s; the feed rate of the gasifying agent can be 20~80m / s, for example 60m / s.

[0049] The positive and progressive effects of this invention are as follows:

[0050] (1) By setting fluidizing agent ports on the side of the distribution plate and setting first gasifying agent ports around the slag discharge port, the present invention increases the reaction temperature, forms a central high-temperature zone, eliminates tar, and expands the range of the central high-temperature zone of the gasifier. While eliminating tar, it also reduces the problem of slag formation in the central high-temperature zone. At the same time, by setting the fluidizing agent ports inclined towards the slag discharge port below the feed port, on the one hand, the material can quickly enter the central high-temperature zone of the gasifier for reaction, and the tar above can be carried into the high-temperature zone to quickly gasify the tar. On the other hand, the downward-facing fluidizing agent ports play a certain flushing role on the distribution plate, which can effectively prevent slag from agglomerating and forming large slag blocks that block the slag discharge port.

[0051] (2) In the fluidized bed gasifier of the present invention, the biomass solid feed enters the gasifier from the feed inlet, is initially accelerated by the inclined feed inlet, and then falls to the distribution plate, where it is accelerated again by the fluidizing agent, thereby quickly reaching the central high temperature zone. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the distribution plate structure described in an embodiment of the present invention.

[0053] Figure 2 This is a partial structural schematic diagram of the fluidized bed gasifier described in an embodiment of the present invention.

[0054] Figure 3 This is a diagram showing the positional relationship between the first gasifying agent inlet and the slag discharge inlet in a fluidized bed gasifier as described in an embodiment of the present invention.

[0055] Figure 4 This is a schematic diagram of the structure of the leak-proof component described in the embodiments of the present invention.

[0056] Explanation of reference numerals in the attached figures:

[0057] Gasifier body 1

[0058] Feed inlet 101

[0059] Distribution plate 2

[0060] Fluidizing agent 201

[0061] First gasifying agent port 202

[0062] Slag discharge port 203

[0063] Second gasifying agent port 204

[0064] Feeding acceleration zone S1

[0065] Bed fluidized zone S2

[0066] Leak-proof component 3

[0067] First support 301

[0068] First through hole 3011

[0069] Limiting step surface 3012

[0070] Second support 302

[0071] 303 sleeve

[0072] First support component 304

[0073] Second support component 305

[0074] Leak-proof part 306 Detailed Implementation

[0075] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0076] Example 1

[0077] This embodiment discloses a fluidized bed gasifier, such as Figures 1-4 As shown, it includes a gasifier body 1 and a distribution plate 2 inside the gasifier body 1.

[0078] The gasifier furnace body 1 is provided with two feed inlets 101. The axis of the feed inlet 101 intersects with the central axis of the gasifier furnace body 1, so that the feeding direction is directly in the center direction of the gasifier furnace body 1.

[0079] The feed inlet 101 is located above the distribution plate 2. The distance Hf between the lower edge of the feed inlet 101 and the upper edge of the distribution plate 2 is 0.18m. The inner diameter Di of the gasifier body 1 is 3.3m, and the total height is 25m. The axis of the feed inlet 101 is inclined towards one end of the slag discharge port 203, and the inclination angle A1 of the feed inlet 101 relative to the horizontal plane is 45°.

[0080] The angle of inclination A4 of the conical surface of the distribution plate 2 relative to the horizontal plane is 45°, and the material of the distribution plate 2 is metal or non-metal refractory material.

[0081] The distribution plate 2 is provided with several fluidizing agent ports 201, a first gasifying agent port 202 and a slag discharge port 203. A pipe is provided in the first gasifying agent port 202 with an inner diameter of 80 mm and the orifice diameter of the fluidizing agent port 201 is 5 mm.

[0082] The distribution plate 2 is cone-shaped, with 5 layers of fluidizing agent ports 201 distributed on the distribution plate. The distance between two adjacent layers along the axial direction of the distribution plate is 300 mm. The number of fluidizing agent ports in each layer from top to bottom is 82, 71, 52, 44 and 22 respectively. The fluidizing agent ports in each layer are equidistantly distributed along the circumference of the distribution plate 2.

[0083] The distribution plate 2 is divided into a feed acceleration zone S1 and a bed fluidization zone S2 along its circumference. Each feed inlet 101 corresponds to a feed acceleration zone S1. The diameter of the feed inlet 101 is L1 = 100 mm, and the chord length of the feed acceleration zone S1 is L2 = 300 mm. The axes of all fluidizing agent inlets 201 located in the feed acceleration zone S1 are inclined towards one end of the slag discharge port 203 at an inclination angle A2 of 15°. The axes of all fluidizing agent inlets 201 located in the bed fluidization zone S2 are inclined at an angle A3 of 0° relative to the horizontal plane, i.e., along the horizontal direction.

[0084] The slag discharge port 203 is located at the bottom of the distribution plate 2, and the diameter of the slag discharge port is 250mm. There are three first gasifying agent ports 202, which are equally spaced around the slag discharge port 203. The three first gasifying agent ports 202 are closer to the slag discharge port 203 than the fluidizing agent port 201. The distance between the axis of the first gasifying agent port and the axis of the slag discharge port is 300mm. The axis of the first gasifying agent port 202 is parallel to the axis of the distribution plate 2 and is vertical. Each first gasifying agent port 202 is provided with a gasifying agent feed pipe. The slag discharge port 203 is provided with a slag discharge pipe. A gasifying agent feed pipe is sleeved inside the slag discharge pipe as a second gasifying agent port 204. The pipe diameter is 150mm. The annular gap formed between the slag discharge pipe and the gasifying agent feed pipe is the slag discharge area.

[0085] The fluidizing agent inlet 201 is equipped with a leak-proof component 3, which is located on the back of the distribution plate 2. The leak-proof component 3 includes a leak-proof part 306 and a connecting part. The leak-proof part 306 is a plate structure made of metal fiber, and the plate has a porous structure for the fluidizing agent to pass through. The pore size of the porous structure is 5~25μm. The connecting part has a perforated structure for the gasifying agent to pass through.

[0086] The connecting part includes a first support 301, a second support 302, a sleeve 303, a first support member 304, and a second support member 305. The first support 301 has a support groove, and the bottom of the groove has a first through hole 3011. The first support member 304, the leak-proof part 306, and the second support member 305 are sequentially arranged in the support groove from top to bottom. One end of the sleeve 303 has a flange, the outer diameter of which is larger than the diameter of the fluidizing agent inlet 201 and smaller than the inner diameter of the support groove. The flange is located inside the support groove. The outer diameter of the other end of the sleeve 303 matches the diameter of the fluidizing agent inlet 201. The second support 302 is a sleeve structure made of metal. The second support 302 is fitted over the flange, and the first support 301 is threaded to the outside of the second support 302.

[0087] A limiting step surface 3012 is provided on the inner side wall of the support groove to limit the screwing depth of the second support 302 in the first support 301, so as to avoid excessive screwing and squeezing the leak-proof part 306.

[0088] The depth of the support groove of the first support 301 is equal to the sum of the thickness of the first support 304, the thickness of the leak-proof part 306, the thickness of the second support 305, and the thickness of the flange of the sleeve 303.

[0089] The sleeve 303 is a ceramic sleeve with a length of 100mm and an inner diameter of 5.0mm. The wall thickness of the end of the sleeve 303 without a flange is 1.5mm.

[0090] Both the first support member 304 and the second support member 305 are steel wire mesh structures with a mesh size of approximately 0.5 mm and a skeleton wire diameter of 0.2 mm.

[0091] During installation, the first support 304, the leak-proof part 306, and the second support 305 are inserted into the support groove of the first support 301. The end of the second support 302 is fixed to the back of the distribution plate 2 by welding. The smaller outer diameter end of the sleeve 303 is inserted into the fluidizing agent port 201 and is secured to the distribution plate 2 on the outer periphery of the fluidizing agent port 201 by the flange of the sleeve 303. The first support 301 is connected to the second support 302 by threads. The gasifying agent enters the furnace body through the second through hole 3011, the porous structure in the leak-proof part, and the pipe hole of the sleeve 303.

[0092] The biomass gasification method in this embodiment includes the following steps:

[0093] Biomass raw materials are introduced through feed inlet 101, fluidizing agent is introduced through fluidizing agent inlet 201, and gasifying agent is introduced through first gasifying agent inlet 202 and second gasifying agent inlet 204 to carry out gasification reaction.

[0094] The biomass pellets are made of Reed spp., and their composition is shown in Table 1. The particle size of the biomass pellets is D50, with a particle size of 6 mm. The feed rate is 12 t / h, the gasification pressure is 2.5 barg, and the gasification temperature is 890~950℃. Both the gasifying agent and the fluidizing agent are a mixture of steam and oxygen. The total flow rate of the gasifying agent is 8.6 t / h, with an oxygen content of 40% and a gasifying agent feed rate of 60 m / s. The total flow rate of the fluidizing agent is 6.4 t / h, with an oxygen content of 10% and a total fluidizing agent flow rate of 6.4 t / h.

[0095] Table 1

[0096]

[0097] The fluidized bed gasifier operates for 24 days.

[0098] The gas exiting the fluidized bed gasifier was cooled and dusted downstream, and its composition was analyzed. The results are as follows:

[0099] H2 32.867

[0100] CO 36.167

[0101] CO2 20.667

[0102] CH4 8.250

[0103] N2 1.523

[0104] Ar 0.069

[0105] H2O 0.457

[0106] Other: 0.001

[0107] Tar component content: Not detected (g / Nm) 3 .

[0108] During operation, no tar components were detected, and no tar accumulation was observed in the furnace. Under normal operation, the discharged slag had a particle size of 3mm, and the particles were relatively uniform, with no solid valve jamming observed. Because the slag discharge pipe and the gasifying agent feed pipe are independently installed, wear on the central air inlet pipe from the slag discharge is avoided.

[0109] During the shutdown and maintenance, no fly ash was found to flow back from the fluidization holes to the outside of the distribution plate, and no fly ash accumulation occurred, which reduced the workload of maintenance and cleaning.

[0110] Comparative Example 1

[0111] The structure of the fluidized bed gasifier in this comparative example is roughly the same as that in Example 1, except that: the lower edge of the feed inlet in this comparative example is 1.2m away from the upper edge of the distribution plate, Hf = 1.2m, the inclination angles A2 and A3 of the fluidizing agent inlet 201 relative to the horizontal plane are both 0°; and no leak-proof component 3 is provided on the back of the distribution plate 2.

[0112] The remaining structure, raw material parameters, and process parameters are the same as in Example 1.

[0113] The fluidized bed gasifier in this comparative example operates for 30 days.

[0114] The gas exiting the fluidized bed gasifier was cooled and dusted downstream, and its composition was analyzed. The results are as follows:

[0115] H2 30.710

[0116] CO 35.413

[0117] CO2 29.927

[0118] CH4 2.874

[0119] N2 0.179

[0120] Ar 0.071

[0121] H2O 0.825

[0122] Other: 0.001

[0123] Tar component content: 1~20g / Nm 3 .

[0124] To reduce tar content, the operating temperature was appropriately increased during operation. However, due to the very low ash melting point of biomass ash, sporadic slag formation occurred during slag discharge, and the slag particle size increased (slag lumps larger than 10mm appeared), far exceeding the 3mm particle size of slag discharge during normal operation. The increased slag particle size also exacerbated the wear between the central tube and the slag discharge tube, causing some solid slag discharge valves to become stuck.

[0125] During shutdown maintenance, it was discovered that fly ash inside the furnace flowed backward from the fluidization orifices to the outside of the distribution plate, accumulating at the bottom of the outer side of the distribution plate. This caused some interference with the air intake, resulting in fluctuations in the operating gasifier pressure and bed height. Furthermore, this accumulated fly ash requires manual cleaning during each maintenance operation, making the workload quite heavy.

Claims

1. A distribution plate for a fluidized bed gasifier, characterized in that, The distribution plate is provided with a plurality of fluidizing agent ports, a first gasifying agent port and a slag discharge port, wherein the aperture of the first gasifying agent port is larger than the aperture of the fluidizing agent port. The distribution plate is cone-shaped, the fluidizing agent inlet is located on the side of the distribution plate, and the slag discharge port is located at the bottom of the distribution plate; the first gasifying agent inlet is located around the slag discharge port and is closer to the slag discharge port than the fluidizing agent inlet; at least a portion of the axis of the fluidizing agent inlet is inclined toward one end of the slag discharge port.

2. The distribution plate of the fluidized bed gasifier as described in claim 1, characterized in that, The fluidized bed gasifier distribution plate meets one or more of the following conditions: ① The axis of the remaining fluidizing agent inlet is inclined toward the end away from the slag discharge port or along the horizontal direction; Furthermore, the chord length L2 of the region formed by all the fluidizing agent ports that are inclined toward one end of the slag discharge port is L1~10L1, where L1 is the diameter of the feed port of the fluidized bed gasifier. Furthermore, the remaining portion of the fluidizing agent inlet has an inclination angle A3 of 0 to 45° relative to the horizontal plane, for example, 0°; ② The angle of inclination A2 of the fluidizing agent inlet, which is inclined toward one end of the slag discharge port, relative to the horizontal plane is 0~30°, but does not include 0°, for example 15°; ③ The orifice diameter of the fluidizing agent inlet is 2~10mm; ④ A plurality of fluidizing agent ports are uniformly distributed on the distribution plate; preferably, 5 to 10 layers of fluidizing agent ports are distributed sequentially from the top to the bottom of the distribution plate, each layer of fluidizing agent ports including a plurality of fluidizing agent ports evenly distributed along the circumference of the distribution plate; the spacing between two adjacent layers of fluidizing agent ports along the axial direction of the distribution plate is preferably 100 to 300 mm.

3. The distribution plate of the fluidized bed gasifier as described in claim 1, characterized in that, The fluidized bed gasifier distribution plate meets one or more of the following conditions: ① The axis of the first gasifying agent inlet is parallel to the central axis of the distribution plate; ② The diameter of the first gasifying agent inlet is 10~200mm; ③ Multiple first gasifying agent ports are evenly distributed along the circumference of the slag discharge port, for example, three ports; ④ The distance between the axis of the first gasifying agent port and the axis of the slag discharge port is 200~500mm, for example 300mm; ⑤ The angle of inclination A4 of the cone surface of the distribution plate relative to the horizontal plane is 30~80°, for example 45° or 60°.

4. The distribution plate of the fluidized bed gasifier as described in claim 1, characterized in that, The fluidizing agent inlet is provided with a leak-proof component, which includes a connecting part and a leak-proof part. One end of the connecting part is connected to the leak-proof part, and the outer diameter of the other end of the connecting part matches the aperture of the fluidizing agent inlet. The leak-proof part is provided with a porous structure for the fluidizing agent to pass through, and the pore size of the porous structure is 0.1~500μm. The connecting part is provided with a perforated structure for the fluidizing agent to pass through.

5. The distribution plate of the fluidized bed gasifier as described in claim 4, characterized in that, The leak-proof part is a block-shaped body, and the block-shaped body is provided with the porous structure. The block-shaped body is made of one or more of the following: metal wire mesh, metal fiber, metal powder and ceramic. And / or, the pore size of the porous structure is 0.1~120μm, for example 5~25μm.

6. The distribution plate of the fluidized bed gasifier as described in claim 4, characterized in that, The connecting part includes a first support and a sleeve. The first support is provided with a support groove, and the bottom of the support groove is provided with a first through hole. The leak-proof part is provided in the support groove. One end of the sleeve is provided with a flange. The outer diameter of the flange is larger than the orifice diameter of the fluidizing agent port and smaller than the inner diameter of the support groove. The flange is located in the support groove. The outer diameter of the other end of the sleeve matches the orifice diameter of the fluidizing agent port. The first through hole and the tube hole of the sleeve form the hole structure. The connecting part preferably further includes a second support, which is a sleeve structure. The second support is sleeved on the outside of the flange, and the first support is threaded to the outside of the second support. The leak-proof component preferably further includes a first support member and a second support member, wherein the first support member, the leak-proof part, and the second support member are arranged sequentially from top to bottom in the support groove, and both the first support member and the second support member are metal mesh structures; the aperture of the metal mesh structure is preferably 0.1~1mm.

7. A fluidized bed gasifier, characterized in that, It includes a gasifier furnace body and a distribution plate disposed at the bottom of the gasifier furnace body, wherein the distribution plate is the fluidized bed gasifier distribution plate according to any one of claims 1 to 6.

8. The fluidized bed gasifier as described in claim 7, characterized in that, The gasifier is provided with a feed inlet, which is located above the distribution plate. The axis of the feed inlet is inclined toward one end of the slag discharge port, and the fluidizing agent port is located directly below the feed inlet. Preferably, the inclination angle A1 of the feed inlet relative to the horizontal plane is 30~80°, for example 45° or 60°; the inclination angle A1 of the feed inlet relative to the horizontal plane is preferably the same as the inclination angle A4 of the conical surface of the distribution plate relative to the horizontal plane; the distance Hf between the lower edge of the feed inlet and the upper edge of the distribution plate is preferably 0~Di, for example 0.48Di or 0.072Di, where Di refers to the inner diameter of the gasifier; the axis of the feed inlet preferably intersects the central axis of the gasifier body. And / or, an air inlet pipe is provided in the slag discharge port, the air inlet pipe forms a second gasifying agent port, and an annular area for slag discharge is provided between the air inlet pipe and the slag discharge port. Preferably, the diameter of the second gasifying agent port accounts for 30-70% of the diameter of the slag discharge port. More preferably, the diameter of the second gasifying agent port is 100-200 mm.

9. A biomass gasification method, characterized in that, It is carried out using the fluidized bed gasifier as described in claim 7 or 8. The biomass gasification method includes the following steps: introducing biomass raw materials through the feed inlet, introducing fluidizing agent through the fluidizing agent inlet, and introducing gasifying agent through the first gasifying agent inlet to carry out the gasification reaction.

10. The biomass gasification method as described in claim 9, characterized in that, The biomass gasification method satisfies one or more of the following ① to ④: ①The fluidizing agent is oxygen or a mixture of oxygen and steam, or a mixture of oxygen, steam and nitrogen, or a mixture of oxygen, steam and carbon dioxide. When the fluidizing agent is a mixture of oxygen and steam, the oxygen content in the mixture is 10-20%. ②The gasifying agent is oxygen or a mixture of oxygen and steam. When the gasifying agent is a mixture of oxygen and steam, the oxygen content in the mixture is 30-60%. ③ The temperature of the gasification reaction is 890~950℃; ④One or more combinations of the biomass raw materials: wood, wheat, corn stalks, rice husks, and reeds; ⑤ The D50 particle size of the biomass raw material pellets is 1~15mm.

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