Biomass fluidized bed gasification system and gasification method suitable for downstream conversion devices

Abstract

The application discloses a biomass fluidized bed gasification system and gasification method suitable for downstream shift device, which comprises a fluidized bed gasification furnace, a cyclone separator, an oxidative cracking furnace, a venturi scrubber, a hydrocyclone and a water washing tower; the fluidized bed gasification furnace, the cyclone separator, the oxidative cracking furnace, the venturi scrubber, the hydrocyclone and the water washing tower are sequentially connected along a synthetic gas flow direction to form a synthetic gas flow route; the system of the application adopts a quenching process, and the water-steam ratio can be about 0.8; the downstream shift device does not need to be supplemented with water vapor, and consumption and investment are saved; the fluidized bed gasification furnace of the application has a high-temperature oxidation zone, tar can be fully cracked, the tar content at the outlet of the fluidized bed gasification furnace is effectively reduced, or there is no tar at the outlet of the fluidized bed gasification furnace.

Description

Technical Field

[0001] This invention relates to a biomass fluidized bed gasification system and gasification method suitable for downstream conversion devices. Background Technology

[0003] Biomass resources are one of the world's zero-carbon clean resources. my country's annual output of biomass from agricultural and forestry waste exceeds 1 billion tons, but the current utilization rate is less than 50%. Converting it into high-end fuels and chemicals through biomass gasification technology has significant social and economic benefits.

[0004] Biomass contains a high content of alkali metal K and halogen Cl, which results in a low ash melting point and makes it prone to problems such as slagging, clogging, corrosion and scaling.

[0005] The methane present in biomass syngas is a useless purge gas for subsequent chemical synthesis, and its presence increases raw material and power consumption.

[0006] For biomass gasification units with downstream conversion converters, the use of waste heat boiler processes would require a large amount of steam to be added to the conversion converters due to the steam-water ratio requirements of the conversion converters, resulting in higher energy consumption and investment. Summary of the Invention

[0007] The technical problem to be solved by the present invention is that the biomass gasification system with downstream conversion device in the prior art has high energy consumption due to the use of waste heat boiler process. The present invention provides a biomass fluidized bed gasification system and gasification method suitable for downstream conversion device. The system of the present invention eliminates the need for the downstream conversion device to supplement steam, thus saving consumption and investment.

[0008] The present invention solves the above-mentioned technical problems through the following technical solution:

[0009] This invention proposes a biomass fluidized bed gasification system suitable for downstream conversion devices, comprising: a fluidized bed gasifier, a cyclone separator, an oxidative pyrolysis furnace, a Venturi scrubber, a hydrocyclone separator, and a water washing tower;

[0010] The fluidized bed gasifier, the cyclone separator, the oxidative cracking furnace, the venturi scrubber, the hydrocyclone separator, and the water washing tower are connected sequentially along the syngas flow direction to form a syngas flow path; the oxidative cracking furnace is provided with a quench zone;

[0011] The fluidized bed gasifier includes a gasifier body and a distribution plate disposed at the bottom of the gasifier body; the distribution plate is conical, and is provided with a plurality of fluidizing agent inlets, a first gasifying agent inlet, and a slag discharge outlet; the fluidizing agent inlets are disposed on the side of the distribution plate, the slag discharge outlet is disposed at the bottom of the distribution plate, the first gasifying agent inlets are disposed around the slag discharge outlet and are closer to the slag discharge outlet than the fluidizing agent inlets; the aperture of the first gasifying agent inlet is larger than the aperture of the fluidizing agent inlet.

[0012] The gasifier furnace body is provided with a feed inlet, which is located above the distribution plate and is inclined towards the slag discharge port; all the fluidizing agent ports located directly below the feed inlet are inclined towards the slag discharge port.

[0013] In this invention, it is understood that the fluidized bed gasifier is a conventional gasifier used in the art for gasifying biomass feedstock to generate syngas, wherein the syngas generally mainly includes H2, CO, CO2, methane and some hydrocarbons.

[0014] 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.

[0015] The fluidized bed gasifier of the present invention improves the reaction temperature and forms a central high-temperature zone by setting fluidizing agent inlets on the side of the distribution plate and first gasifying agent inlets around the slag discharge port. This eliminates tar and expands the range of the central high-temperature zone of the gasifier, reducing the problem of slagging in the central high-temperature zone while eliminating tar. At the same time, by setting the fluidizing agent inlets 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, bringing the tar above into the high-temperature zone and quickly gasifying the tar. On the other hand, the downward-facing fluidizing agent inlets have a certain flushing effect on the distribution plate, which can effectively prevent slag from agglomerating and forming large slag blocks that block the slag discharge port.

[0016] 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°.

[0017] 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.

[0018] 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 body.

[0019] 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.

[0020] In this invention, the slag discharge port is preferably further provided with an air inlet pipe, which 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.

[0021] 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 0~30°, but does not include 0°, for example 15°.

[0022] In this invention, it is understood that, except for all the fluidizing agent ports located directly below the feed inlet, the axis of the remaining fluidizing agent ports may be inclined towards one end of the slag discharge port, or towards one end away from the slag discharge port, or in a horizontal direction. Preferably, the axis of the remaining fluidizing agent ports is inclined towards one end away from the slag discharge port or in a horizontal direction; furthermore, the chord length L2 of the region formed by all the fluidizing agent ports inclined towards the slag discharge port is L1~10L1, where L1 is the diameter of the feed inlet. If the width of the feed acceleration zone is too narrow, it cannot guarantee that all feed can be accelerated; if it is too wide, it not only accelerates the feed but also accelerates the entry of peripheral ash and slag into the central high-temperature zone, competing for the gasifying agent, resulting in incomplete gasification.

[0023] 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.

[0024] 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.

[0025] In this invention, a plurality of fluidizing agent outlets are uniformly distributed on the distribution plate.

[0026] 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.

[0027] 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.

[0028] In this invention, preferably, multiple first gasifying agent ports are evenly distributed along the circumference of the slag discharge port, for example, three ports. 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 this 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.

[0029] In this invention, the slag discharge port is preferably further provided with an air inlet pipe, which 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.

[0030] 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.

[0031] In this invention, the diameter of the first gasifying agent inlet is preferably 10-200 mm, for example 80 mm.

[0032] In this invention, the orifice diameter of the fluidizing agent port is preferably 2-10 mm, for example 5 mm or 7 mm.

[0033] In this invention, the angle of inclination A4 of the cone surface of the distribution plate relative to the horizontal plane is preferably 30~80°, for example 45° or 60°.

[0034] 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.

[0035] In this invention, the distribution plate is made of metal and / or non-metallic refractory materials.

[0036] 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 gasifying 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.

[0037] 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.

[0038] 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.

[0039] The hole structure on the connecting part can be conventional in the art, such as through holes or mesh holes.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] In this invention, the biomass fluidized bed gasification system suitable for downstream conversion devices preferably further includes a slag-water unit. The oxidative cracking furnace, the hydrocyclone separator, and the water washing tower are all connected to the inlet of the slag-water unit. The slag-water unit is used to collect ash water from the oxidative cracking furnace, the hydrocyclone separator, and the water washing tower.

[0044] More preferably, the slag-water unit, the water washing tower, and the quench zone of the oxidative cracking furnace are connected in series to form an ash-water circulation route, which is used to return the ash-water treated by the slag-water unit to the water washing tower and the oxidative cracking furnace in sequence. In the ash-water circulation route, the ash-water first returns to the water washing tower to separate the ash and slag from the ash-water, and then returns to the quench zone of the oxidative cracking furnace to cool and remove dust from the gas in the oxidative cracking furnace.

[0045] It is understood that the slag-water unit is a conventional device in the art for flocculation, sedimentation, and separation of ash water. The slag-water unit generally includes a flash tank, a settling tank, an ash water tank, and a stripping tower connected in sequence. The flash tank is connected to the ash water outlet of the oxidative cracking furnace, the ash water outlet of the hydrocyclone separator, and the ash water outlet of the washing tower, respectively. The stripping tower is connected to the ash water circulation return port of the washing tower.

[0046] In this invention, preferably, a feed leg device is further provided between the cyclone separator and the fluidized bed gasifier, the feed leg device being used to return fly ash to the fluidized bed gasifier for further secondary reaction. The feed leg device is conventional in the art.

[0047] In this invention, it is understood that the fluidized bed gasifier is generally also provided with a syngas outlet, a fly ash return port and a slag discharge port. The syngas outlet is connected to the syngas inlet of the cyclone separator, and the fly ash return port is connected to the fly ash discharge port of the cyclone separator.

[0048] Preferably, the biomass feedstock inlet and the fly ash return outlet are both located on the lower side of the fluidized bed gasifier, the syngas outlet is preferably located at the top of the fluidized bed gasifier, and the slag discharge outlet is preferably located at the bottom of the fluidized bed gasifier.

[0049] In this invention, it is understood that the cyclone separator is a conventional device in the art for separating the gaseous, solid, and liquid components from the syngas exiting the fluidized bed gasifier. The cyclone separator typically includes a syngas inlet, a syngas outlet, and a fly ash outlet.

[0050] The fly ash outlet is preferably located at the bottom of the cyclone separator, the syngas inlet is preferably located on the upper side of the cyclone separator, and the syngas outlet is preferably located at the top of the cyclone separator.

[0051] In this invention, it is understood that the oxidative cracking furnace is a conventional device used in the art to oxidize and crack methane and some hydrocarbons in syngas into CO and H2. By setting up the oxidative cracking furnace, the content of effective gases (H2, CO) can be increased. The oxidative cracking furnace is generally provided with a reaction zone and a quench zone. The quench zone is preferably provided with a quench ring to evenly distribute quench water.

[0052] The oxidative cracking furnace is generally equipped with a syngas inlet, an ash water outlet, and a syngas outlet. The syngas inlet is connected to the syngas outlet of the cyclone separator, and the syngas outlet is connected to the air inlet of the Venturi scrubber.

[0053] Preferably, the ash water outlet is connected to the liquid inlet of the slag water unit.

[0054] Preferably, the oxidative cracking furnace is also equipped with an ash water circulation return port, which is connected to the ash water outlet of the water washing tower. A pump is preferably installed on the connection line between the ash water circulation return port and the ash water outlet of the water washing tower.

[0055] Preferably, the syngas inlet is located at the top of the oxidative cracking furnace, the ash water outlet is located at the bottom of the oxidative cracking furnace, the syngas outlet is located on the lower side of the oxidative cracking furnace, and the ash water circulation return port is located on the middle side of the oxidative cracking furnace.

[0056] The oxidative cracking furnace is preferably a non-catalytic oxidative cracking furnace, which, compared with a catalytic conversion furnace, can reduce catalyst deactivation or blockage caused by H2S and fly ash in the crude syngas.

[0057] In this invention, it is understood that the Venturi scrubber is a conventional device in the art for removing dust from the gas exiting the oxidative cracking furnace. The Venturi scrubber generally has an air inlet, a scrubbing liquid inlet, and an air outlet. The air inlet is connected to the syngas outlet of the oxidative cracking furnace, and the air outlet is connected to the air inlet of the hydrocyclone separator.

[0058] Preferably, the washing liquid inlet is connected to the slag and water unit, and is used to use the ash water returned by the slag and water unit as the washing liquid for the Venturi scrubber.

[0059] The washing liquid inlet is preferably located on the side of the Venturi scrubber, and the air inlet and air outlet are preferably located at opposite ends of the Venturi scrubber.

[0060] In this invention, it is understood that the hydrocyclone separator is a conventional device in the art for separating suspended materials from the Venturi scrubber. The hydrocyclone separator generally has an air inlet, an air outlet, and a ash water outlet; the air inlet is connected to the air outlet of the Venturi scrubber, and the air outlet is connected to the air inlet of the water washing tower.

[0061] Preferably, the ash water outlet is connected to the liquid inlet of the slag water unit.

[0062] The air inlet is preferably located on the upper side of the hydrocyclone, and the air outlet and the ash water outlet are preferably located at the top and bottom of the hydrocyclone, respectively.

[0063] In this invention, it is understood that the water washing tower is a conventional device in the art for washing syngas. The water washing tower is generally equipped with an air inlet, an air outlet, an ash water outlet, and a water inlet. The air inlet is connected to the outlet gas of the hydrocyclone, and the ash water outlet is connected to the liquid inlet of the slag-water unit.

[0064] Preferably, the water washing tower is also provided with an ash water circulation return port, which is connected to the liquid outlet of the slag water unit.

[0065] Preferably, the ash water outlet is also connected to the ash water circulation return port of the oxidative cracking furnace.

[0066] Preferably, the air outlet and the ash water outlet are respectively located at the top and bottom of the water washing tower, the air inlet and the ash water circulation return outlet are preferably both located on the lower side of the water washing tower, and the water inlet is preferably located on the upper side of the water washing tower.

[0067] This invention also proposes a biomass fluidized bed gasification method suitable for downstream shift converters, which employs the aforementioned biomass fluidized bed gasification system suitable for downstream shift converters, and specifically includes the following steps:

[0068] Biomass feedstock is introduced through the feed inlet, fluidizing agent is introduced through the fluidizing agent inlet, and gasifying agent is introduced through the first gasifying agent inlet to carry out the gasification reaction. The resulting crude syngas is then processed sequentially through the cyclone separator, the oxidative cracking furnace, the Venturi scrubber, the hydrocyclone separator, and the water washing tower.

[0069] In this invention, when the aforementioned second vaporizing agent port is also included, the vaporizing agent is introduced through the second vaporizing agent port.

[0070] In this invention, when the aforementioned feed leg device is used, the gasification method further includes: returning the fly ash separated from the cyclone separator to the fluidized bed gasifier via the feed leg device.

[0071] In this invention, when the aforementioned slag-water unit is used, the gasification method further includes: collecting ash water from the oxidative cracking furnace, the hydrocyclone separator, and the water washing tower through the slag-water unit, and performing sedimentation and separation treatment on the ash water.

[0072] In this invention, when the aforementioned ash water circulation route is adopted, the gasification method further includes: the liquid portion obtained after treatment by the slag water unit is returned to the water washing tower for washing, and then enters the quenching zone of the oxidative cracking furnace as quench water to quench the syngas.

[0073] In this invention, when the washing liquid inlet of the Venturi scrubber is connected to the sludge-water unit, the gasification method further includes: using the liquid portion obtained by the sludge-water unit as the washing liquid of the Venturi scrubber.

[0074] In this invention, it is understood that the fluidizing agent and the gasifying agent are conventional in the art.

[0075] The fluidizing agent may be oxygen, a mixture of oxygen and steam, 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 preferably 10-20%, for example, 10%.

[0076] The vaporizing agent may be oxygen or a mixture of oxygen and steam. When the vaporizing agent is a mixture of oxygen and steam, the oxygen content in the mixture is preferably 30-60%, for example, 40%.

[0077] 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.

[0078] In this invention, the temperature of the gasification reaction is conventional in the art, for example, 700~1300℃, for example, 820℃.

[0079] In this invention, the pressure inside the fluidized bed gasifier is conventional in the art, for example, 0.5~80 barg, such as 40 barg.

[0080] In this invention, it is understood that the biomass raw materials are conventional, such as one or more combinations of wood, wheat, corn stalks, rice husks, and reeds.

[0081] In this invention, the maximum particle size of the biomass raw material particles is preferably <10mm.

[0082] The positive and progressive effects of this invention are as follows:

[0083] (1) In the traditional waste heat boiler process, the water vapor content in the syngas at the outlet of the water washing tower is extremely low, around 0.02%. However, the system of the present invention adopts a quench process, and the water vapor ratio can be around 0.8. The downstream conversion device does not need to supplement water vapor, saving consumption and investment.

[0084] (2) Since biomass contains a large amount of alkali metals, if the waste heat boiler process is used, it is easy to cause scale and corrosion of the waste heat boiler. However, the system of the present invention adopts the quench process, and the alkali metals are carried into the water system by the quench water. The concentration is very low and there will be no scale and corrosion.

[0085] (3) Since biomass contains a large amount of chloride ions, if the waste heat boiler process is used, the chloride ion content at the water washing tower is as high as 5000~10000ppm, which causes serious corrosion of the water washing system pipeline. However, the system of the present invention adopts a quench process, and the water circulation can dilute the chloride ion concentration, which can reduce the chloride ion content at the water washing tower to below 50~500ppm, which can effectively solve the chloride ion corrosion problem.

[0086] (4) The temperature at the flame of a general oxidative cracking furnace is very high, which will cause some fly ash to melt. If a waste heat boiler process is used, it will cause problems such as blockage and scaling of the waste heat boiler. However, the system of the present invention adopts a quench process, and the molten slag and fly ash are carried to the slag water system for treatment by the quench water, so there is no blockage problem.

[0087] (5) The fluidized bed gasifier in the system of the present invention has a high-temperature oxidation zone, which can fully crack the tar, effectively reduce the tar content at the outlet of the fluidized bed gasifier or make the outlet of the fluidized bed gasifier free of tar, and the effective gas in the syngas can reach more than 65%, which greatly improves the yield of effective gas from biomass gasification; while for traditional biomass gasification technology, due to the influence of slagging in the gasifier, the gasification temperature cannot be increased, and the tar content is 50~100g / Nm 3The presence of methane (above 10%) results in a low effective gas content in the syngas, below 50%. Attached Figure Description

[0088] Figure 1 This is a schematic diagram of the structure of the biomass gasification system described in an embodiment of the present invention.

[0089] Figure 2 This is a schematic diagram of the distribution plate structure described in Embodiment 1 of the present invention.

[0090] Figure 3 This is a partial structural schematic diagram of the fluidized bed gasifier described in Embodiment 1 of the present invention.

[0091] Figure 4 This is a diagram showing the positional relationship between the first gasifying agent inlet and the slag discharge inlet in the fluidized bed gasifier as described in Embodiment 1 of the present invention.

[0092] Figure 5 This is a schematic diagram of the leak-proof component described in Embodiment 1 of the present invention.

[0093] Explanation of reference numerals in the attached figures:

[0094] Fluidized bed gasifier 1

[0095] Gasifier 101

[0096] Feed inlet 1011

[0097] Distribution plate 102

[0098] Fluidizing agent 1021

[0099] First gasifying agent port 1022

[0100] Slag discharge port 1023

[0101] Second gasifying agent 1024

[0102] Feeding acceleration zone S1

[0103] Bed fluidized zone S2

[0104] Leak-proof component 103

[0105] First support 1031

[0106] First through hole 10311

[0107] Limiting step surface 10312

[0108] Second support 1032

[0109] Casing 1033

[0110] First support component 1034

[0111] Second support component 1035

[0112] Leak-proof section 1036

[0113] Cyclone Separator 2

[0114] Oxidation cracking furnace 3

[0115] Venturi scrubber 4

[0116] Hydrocyclone separator 5

[0117] Water washing tower 6

[0118] Slag and water unit 7

[0119] Material leg device 8

[0120] Pump 9 Detailed Implementation

[0121] 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.

[0122] Example 1

[0123] This embodiment discloses a fluidized bed gasifier, such as Figures 2-5 As shown, it includes a gasifier body 101 and a distribution plate 102 inside the gasifier body 101.

[0124] The gasifier body 101 is provided with two feed inlets 1011. The axis of the feed inlet 1011 intersects the central axis of the gasifier body 101, so that the feeding direction is directly in the center direction of the gasifier body 101.

[0125] The feed inlet 1011 is located above the distribution plate 102. The distance Hf between the lower edge of the feed inlet 1011 and the upper edge of the distribution plate 102 is 0.18m. The inner diameter Di of the gasifier body 101 is 3.3m, and the total height is 25m. The axis of the feed inlet 1011 is inclined towards one end of the slag discharge port 1023, and the inclination angle A1 of the feed inlet 1011 relative to the horizontal plane is 45°.

[0126] The angle of inclination A4 of the conical surface of the distribution plate 102 relative to the horizontal plane is 45°, and the material of the distribution plate 102 is metal or non-metal refractory material.

[0127] The distribution plate 102 is provided with several fluidizing agent ports 1021, a first gasifying agent port 1022 and a slag discharge port 1023. A pipe is provided in the first gasifying agent port 1022 with an inner diameter of 80 mm. The diameter of the fluidizing agent port 1021 is 5 mm.

[0128] The distribution plate 102 is cone-shaped, with 5 layers of fluidizing agent ports 1021 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 102.

[0129] The distribution plate 102 is divided into a feed acceleration zone S1 and a bed fluidization zone S2 along its circumference. Each feed inlet 1011 corresponds to a feed acceleration zone S1. The diameter of the feed inlet 1011 is L1 = 100 mm, and the chord length of the feed acceleration zone S1 is L2 = 300 mm. The axis of the fluidizing agent inlet 1021 located in the feed acceleration zone S1 is inclined towards the end of the slag discharge port 1023 at an inclination angle A2 of -15°. The axis of all fluidizing agent inlets 1021 located in the bed fluidization zone S2 is inclined at an angle A3 of 0° relative to the horizontal plane, i.e., along the horizontal direction.

[0130] The slag discharge port 1023 is located at the bottom of the distribution plate 102. There are three first gasifying agent ports 1022, which are equally spaced around the slag discharge port 1023. 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 1022 is parallel to the axis of the distribution plate 102 and is vertical. Each first gasifying agent port 1022 is provided with a gasifying agent feed pipe. The slag discharge port 1023 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 1024. 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.

[0131] A leak-proof component 103 is provided at the fluidizing agent inlet 1021, and the leak-proof component 103 is located on the back side of the distribution plate 102. The leak-proof component 103 includes a leak-proof part 1036 and a connecting part. The leak-proof part 1036 is a plate structure made of metal fiber, and the plate has a porous structure for the gasifying 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.

[0132] The connecting part includes a first support 1031, a second support 1032, a sleeve 1033, a first support member 1034, and a second support member 1035. The first support 1031 has a support groove, and the bottom of the groove has a first through hole 10311. The first support member 1034, the leak-proof part 1036, and the second support member 1035 are arranged sequentially from top to bottom in the support groove. One end of the sleeve 1033 has a flange, the outer diameter of which is larger than the diameter of the fluidizing agent inlet 1021 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 1033 matches the diameter of the fluidizing agent inlet 1021. The second support 1032 is a sleeve structure made of metal. The second support 1032 is fitted over the flange, and the first support 1031 is threaded to the outside of the second support 1032.

[0133] A limiting step surface 10312 is provided on the inner side wall of the support groove to limit the screwing depth of the second support 1032 in the first support 1031, so as to avoid excessive screwing and squeezing the leak-proof part 1036.

[0134] The depth of the support groove of the first support 1031 is equal to the sum of the thickness of the first support member 1034, the thickness of the leak-proof part 1036, the thickness of the second support member 1035, and the thickness of the flange of the sleeve 1033.

[0135] The sleeve 1033 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 1033 without a flange is 1.5mm.

[0136] Both the first support member 1034 and the second support member 1035 are steel wire mesh structures with a mesh size of approximately 0.5 mm and a skeleton wire diameter of 0.2 mm.

[0137] During installation, the first support 1034, the leak-proof part 1036, and the second support 1035 are inserted into the support groove of the first support 1031. The end of the second support 1032 is fixed to the back of the distribution plate 102 by welding. The smaller outer diameter end of the sleeve 1033 is inserted into the fluidizing agent port 1021 and is secured to the distribution plate 102 on the outer periphery of the fluidizing agent port 1021 by the flange of the sleeve 1033. The first support 1031 is connected to the second support 1032 by threads. The gasifying agent enters the furnace body through the second through hole 10311, the porous structure in the leak-proof part, and the pipe hole of the sleeve 1033.

[0138] Example 2

[0139] This embodiment discloses a biomass fluidized bed gasification system suitable for downstream conversion devices, such as... Figure 1 As shown, it includes: a fluidized bed gasifier 1, a cyclone separator 2, an oxidative cracking furnace 3, a venturi scrubber 4, a hydrocyclone separator 5, a water washing tower 6, and a slag-water unit 7.

[0140] Among them, fluidized bed gasifier 1 is the fluidized bed gasifier described in Example 1.

[0141] The gasifier body 101 is also equipped with a syngas outlet, a fly ash return port and a slag discharge port. The syngas outlet is located at the top of the gasifier body 101, the slag discharge port is located at the bottom of the gasifier body 101, and the fly ash return port is located on the lower side of the gasifier body 101.

[0142] Cyclone separator 2 is used to separate the solid and liquid components in the syngas coming out of the fluidized bed gasifier; wherein, cyclone separator 2 is provided with a syngas inlet, a syngas outlet and a fly ash outlet, the fly ash outlet is located at the bottom of cyclone separator 2, the syngas inlet is located on the upper side of cyclone separator 2 and the syngas outlet is located at the top of cyclone separator 2.

[0143] The bottom of the cyclone separator is equipped with a material leg device 8, which is connected between the fly ash discharge port of the cyclone separator 2 and the fly ash return port of the gasifier body 101, and is used to return the fly ash to the fluidized bed gasifier 1 for secondary reaction.

[0144] The oxidative cracking furnace 3 includes a reaction zone and a quench zone. The quench zone is equipped with a quench ring for uniformly distributing quench water. The oxidative cracking furnace 3 is equipped with a syngas inlet, an ash water outlet, a syngas outlet, and an ash water circulation return port. The syngas inlet is located at the top of the oxidative cracking furnace 3, the ash water outlet is located at the bottom of the oxidative cracking furnace 3, the syngas outlet is located on the lower side of the oxidative cracking furnace 3, and the ash water circulation return port is located on the middle side of the oxidative cracking furnace 3.

[0145] The Venturi scrubber 4 is used to remove dust from the gas coming out of the oxidative cracking furnace. The Venturi scrubber 4 is equipped with an air inlet, a scrubbing liquid inlet, and an air outlet. The scrubbing liquid inlet is located on the side of the Venturi scrubber 4, and the air inlet and air outlet are located at both ends of the Venturi scrubber 4, respectively.

[0146] The hydrocyclone separator 5 is used to separate suspended materials from the Venturi scrubber 4. The hydrocyclone separator is equipped with an air inlet, an air outlet, and an ash water outlet. The air inlet is located on the upper side of the hydrocyclone separator, and the air outlet and ash water outlet are located at the top and bottom of the hydrocyclone separator 5, respectively.

[0147] The water washing tower 6 is used to further wash the syngas. The water washing tower 6 is equipped with an air inlet, an air outlet, an ash water outlet, an ash water circulation return inlet, and a water inlet. The air outlet and the ash water outlet are respectively located at the top and bottom of the water washing tower 6. The air inlet and the ash water circulation return inlet are both located on the lower side of the water washing tower 6, and the water inlet is located on the upper side of the water washing tower 6.

[0148] The slag and water unit 7 is used for flocculation, sedimentation and separation of ash water. The slag and water unit 7 includes a flash tank, a settling tank, an ash water tank and a stripping tower connected in sequence.

[0149] The syngas outlet of the gasifier body 101 is connected to the syngas inlet of the cyclone separator 2. The syngas outlet of the cyclone separator 2 is connected to the syngas inlet of the oxidative cracking furnace 3. The syngas outlet of the oxidative cracking furnace 3 is connected to the inlet of the Venturi scrubber. The outlet of the Venturi scrubber is connected to the inlet of the hydrocyclone separator 5. The washing liquid inlet of the Venturi scrubber 4 is connected to the stripping tower outlet of the slag and water unit 7. The returned ash water is used as the washing liquid of the Venturi scrubber 4. The outlet of the hydrocyclone separator 5 is connected to the inlet of the water washing tower 6, forming a syngas flow path.

[0150] The fly ash return port of the gasifier body 101 is connected to one end of the material leg device 8, and the other end of the material leg device 8 is connected to the fly ash discharge port of the cyclone separator 2.

[0151] The flash tank in slag-water unit 7 is connected to the ash-water outlets of the oxidative cracking furnace 3, the hydrocyclone 5, and the washing tower 6, respectively. The stripping tower in slag-water unit 7 is connected to the ash-water circulation return port of the washing tower 6, and the ash-water outlet of the washing tower 6 is connected to the ash-water circulation return port of the oxidative cracking furnace 3, forming an ash-water circulation route. A pump 9 is installed on the connection line between the ash-water circulation return port of the oxidative cracking furnace 3 and the ash-water outlet of the washing tower 6. The ash-water first returns to the washing tower 6 to separate the ash and slag from the ash-water, and then returns to the quench zone of the oxidative cracking furnace 3 to cool and remove dust from the gas in the oxidative cracking furnace 3.

[0152] Example 3

[0153] This embodiment discloses a biomass fluidized bed gasification method suitable for a downstream conversion device, which is carried out using the biomass fluidized bed gasification system suitable for a downstream conversion device described in Example 2.

[0154] The gasification method specifically includes the following steps:

[0155] Biomass feedstock is introduced through feed inlet 1011, fluidizing agent is introduced through fluidizing agent inlet 1021, and gasifying agent is introduced through first gasifying agent inlet 1022 and second gasifying agent inlet 1024 to carry out gasification reaction. The resulting crude syngas is processed sequentially through cyclone separator 2, oxidative cracking furnace 3, venturi scrubber 4, hydrocyclone separator 5 and water washing tower 6.

[0156] During the process, the fly ash separated from the cyclone separator 2 is returned to the fluidized bed gasifier 1. The ash water from the oxidative cracking furnace 3, the cyclone separator 5 and the water washing tower 6 enters the slag water unit 7. The liquid part of the ash water after being processed by the slag water unit 7 is returned to the water washing tower 6 for washing, and then enters the quenching zone of the oxidative cracking furnace 3 as quench water to quench the syngas.

[0157] The raw material is biomass pellets, which are one or more combinations of wheat, corn stalks, rice husks, and reeds. The maximum particle size of the pellets is <10mm, and the external moisture content is <4%. The feed rate is 50t / h, fed at ambient temperature, with a gasification pressure of 40 barg and a gasification temperature of 820℃. Both the fluidizing agent and the gasifying agent are a mixture of oxygen and water vapor. The gasifying agent has an oxygen content of 40% and a feed velocity of 60m / s. The fluidizing agent has an oxygen content of 10% and a feed velocity of 0.3m / s. The total flow rate of the gasifying agent and the fluidizing agent combined is 15t / h, with the total flow rate of the gasifying agent being 8.6t / h and the total flow rate of the fluidizing agent being 6.4t / h. The volume of the fluidized bed gasifier is 220 m³. 3 .

[0158] The system runtime of this embodiment is 200 days.

[0159] Implementation results:

[0160] The residence time of biomass pellets in the gasifier body 101 is >20s, and the outlet of the fluidized bed gasifier 1 is free of tar.

[0161] After quenching, the syngas water-to-vapor ratio reaches about 0.8, saving energy consumption in the downstream conversion unit.

[0162] After quenching, the chloride ion concentration in the greywater is reduced to below 50-500 ppm, and the alkali metal concentration is trace.

[0163] The composition of the syngas exiting from water washing tower 6 was monitored, and the effective gas content in the syngas was >65%.

Claims

1. A biomass fluidized bed gasification system suitable for downstream shift converters, characterized in that, It includes: fluidized bed gasifier, cyclone separator, oxidative cracking furnace, venturi scrubber, hydrocyclone separator and water washing tower; The fluidized bed gasifier, the cyclone separator, the oxidative cracking furnace, the venturi scrubber, the hydrocyclone separator, and the water washing tower are connected sequentially along the syngas flow direction to form a syngas flow path; the oxidative cracking furnace is provided with a quench zone; The fluidized bed gasifier includes a gasifier body and a distribution plate disposed at the bottom of the gasifier body; the distribution plate is conical, and is provided with a plurality of fluidizing agent inlets, a first gasifying agent inlet, and a slag discharge outlet; the fluidizing agent inlets are disposed on the side of the distribution plate, the slag discharge outlet is disposed at the bottom of the distribution plate, the first gasifying agent inlets are disposed around the slag discharge outlet and are closer to the slag discharge outlet than the fluidizing agent inlets; the aperture of the first gasifying agent inlet is larger than the aperture of the fluidizing agent inlet. The gasifier furnace body is provided with a feed inlet, which is located above the distribution plate and is inclined towards the slag discharge port; all the fluidizing agent ports located directly below the feed inlet are inclined towards the slag discharge port.

2. The biomass fluidized bed gasification system suitable for downstream conversion devices as described in claim 1, characterized in that, The fluidized bed gasifier meets one or more of the following conditions: ① The inclination angle A1 of the feed inlet relative to the horizontal plane is 30~80°, for example 45° or 60°; ② The inclination angle A1 of the feed inlet relative to the horizontal plane is the same as the inclination angle A4 of the cone surface of the distribution plate relative to the horizontal plane; ③ The distance Hf between the lower edge of the feed inlet and the upper edge of the distribution plate is 0~Di, for example 0.48Di or 0.072Di, where Di refers to the inner diameter of the gasifier body; ④ The axis of the feed inlet intersects with the central axis of the gasifier body; ⑤ 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°; ⑥ An air inlet pipe is also provided in the slag discharge port, 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; 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, and the diameter of the slag discharge port is 200-300 mm; ⑦ 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; ⑧ Except for all the fluidizing agent ports located directly below the feed inlet, the axes of the remaining fluidizing agent ports are inclined toward the end away from the slag discharge port or along the horizontal direction; furthermore, the inclination angle A3 of the remaining fluidizing agent ports relative to the horizontal plane is 0~45°, for example 0°.

3. The biomass fluidized bed gasification system suitable for downstream conversion devices as described in claim 1, characterized in that, The fluidized bed gasifier meets one or more of the following conditions: ① The orifice diameter of the fluidizing agent inlet is 2~10mm; ② 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 axis of the first gasifying agent inlet is parallel to the central axis of the distribution plate; ④ The diameter of the first gasifying agent inlet is 10~200mm; ⑤ Multiple first gasifying agent ports are evenly distributed along the circumference of the slag discharge port; the distance between the axis of the first gasifying agent port and the axis of the slag discharge port is preferably 200~500mm, for example 300mm. ⑥ 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 biomass fluidized bed gasification system suitable for downstream conversion devices as described in any one of claims 1 to 3, 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 gasifying agent to pass through. 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 biomass fluidized bed gasification system suitable for downstream conversion devices as described in claim 4, characterized in that, The leak-proof component meets one or more of the following conditions: ① The leak-proof part is a block-shaped body, and the block-shaped body is provided with the porous structure; ② The pore size of the porous structure is 0.1~120μm, for example 5~25μm; ③ 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.

6. The biomass fluidized bed gasification system suitable for downstream conversion devices as described in claim 5, characterized in that, 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. The leak-proof component further includes a first support member and a second support member. The first support member, the leak-proof part, and the second support member are arranged sequentially from top to bottom in the support groove. 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. The biomass fluidized bed gasification system suitable for downstream conversion devices as described in claim 1, characterized in that, The biomass fluidized bed gasification system suitable for downstream conversion devices meets one or more of the following conditions: ①The biomass fluidized bed gasification system suitable for downstream conversion devices also includes a slag-water unit. The oxidative cracking furnace, the hydrocyclone separator, and the water washing tower are all connected to the inlet of the slag-water unit. The slag-water unit is used to collect ash water from the oxidative cracking furnace, the hydrocyclone separator, and the water washing tower. ②A material leg device is also provided between the cyclone separator and the fluidized bed gasifier, the material leg device being used to return fly ash to the fluidized bed gasifier.

8. The biomass fluidized bed gasification system suitable for downstream conversion devices as described in claim 7, characterized in that, When the slag-water unit is provided, the biomass fluidized bed gasification system suitable for downstream conversion devices meets one or more of the following conditions: ①The slag water unit, the water washing tower, and the quenching zone of the oxidative cracking furnace are connected in series to form an ash water circulation route, which is used to return the ash water treated by the slag water unit to the water washing tower and the oxidative cracking furnace in sequence. ②The slag and water unit includes a flash tank, a settling tank, an ash water tank and a stripping tower connected in sequence. The flash tank is connected to the ash water outlet of the oxidative cracking furnace, the ash water outlet of the hydrocyclone separator and the ash water outlet of the water washing tower respectively. The stripping tower is connected to the ash water circulation return port of the water washing tower. ③ The washing liquid inlet of the Venturi scrubber is connected to the slag and water unit, and is used to use the ash water returned by the slag and water unit as the washing liquid of the Venturi scrubber.

9. A biomass fluidized bed gasification method suitable for downstream shift converters, characterized in that, It employs the biomass fluidized bed gasification system suitable for downstream conversion devices as described in any one of claims 1 to 8, and specifically includes the following steps: Biomass feedstock is introduced through the feed inlet, fluidizing agent is introduced through the fluidizing agent inlet, and gasifying agent is introduced through the first gasifying agent inlet to carry out the gasification reaction. The resulting crude syngas is then processed sequentially through the cyclone separator, the oxidative cracking furnace, the Venturi scrubber, the hydrocyclone separator, and the water washing tower.

10. The biomass fluidized bed gasification method suitable for downstream conversion devices as described in claim 9, characterized in that, The biomass fluidized bed gasification method suitable for downstream conversion devices satisfies one or more of the following conditions: (1) When the material leg device as described in claim 7 is used, the gasification method further includes: returning the fly ash separated from the cyclone separator to the fluidized bed gasifier through the material leg device; (2) When the slag-water unit as described in claim 7 is used, the gasification method further includes: collecting ash water from the oxidative cracking furnace, the hydrocyclone separator and the water washing tower through the slag-water unit, and performing sedimentation and separation treatment on the ash water; (3) When the ash water circulation route as described in claim 8 is adopted, the gasification method further includes: the liquid portion obtained by the slag water unit is returned to the water washing tower for washing, and then enters the quenching zone of the oxidative cracking furnace as quenching water to quench the syngas. (4) When the washing liquid inlet of the Venturi scrubber is connected to the sludge-water unit, the gasification method further includes: using the liquid portion obtained by the sludge-water unit as the washing liquid of the Venturi scrubber. (5) When the biomass fluidized bed gasification system suitable for downstream conversion device further includes the second gasifying agent port of claim 2, the gasifying agent is introduced through the second gasifying agent port; (6) The biomass raw materials are one or more of the following: wood, wheat, corn stalks, rice husks, and reeds; (7) The biomass raw material is in granular form, and the maximum particle size is <10mm; (8) The 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%; (9) The 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%; (10) The feed rate of the fluidizing agent is 0.2~2m / s; (11) The feeding rate of the gasifying agent is 20~80m / s; (12) The temperature of the gasification reaction is 700~1300℃, for example 820℃.

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