Biomass fluidized bed gasification system suitable for downstream conversion device

Abstract

The utility model discloses a biomass fluidized bed gasification system suitable for a downstream conversion device. The biomass fluidized bed gasification system comprises a fluidized bed gasification furnace, a cyclone separator, an oxidation cracking furnace, a venturi scrubber, a cyclone hydraulic separator and a water scrubber, the fluidized bed gasification furnace, the cyclone separator, the oxidation cracking furnace, the venturi scrubber, the hydrocyclone and the water scrubber are sequentially connected along the flow direction of synthesis gas to form a synthesis gas flow route; the system disclosed by the utility model adopts a chilling process, the water-vapor ratio can be about 0.8, a downstream conversion device does not need to be supplemented with water vapor, the consumption and the investment are saved, and the fluidized bed gasification furnace has a high-temperature oxidation area, so that tar can be fully cracked, and the energy consumption is reduced. The tar content at the outlet of the fluidized bed gasifier is effectively reduced or no tar exists at the outlet of the fluidized bed gasifier.

Description

Technical Field

[0001] The utility model relates to a biomass fluidized bed gasification system suitable for a downstream conversion device. Background Art

[0002] The high content of alkali metal K and halogen CL in biomass leads to a low melting point of biomass ash, which easily causes problems such as slagging, blockage, corrosion and scaling.

[0003] The methane present in biomass synthesis gas is useless purge gas for subsequent chemical synthesis. The presence of methane increases raw material consumption and power consumption.

[0004] For biomass gasification units with a conversion device downstream, due to the requirements of the conversion device on the water-steam ratio, if the waste heat boiler process is adopted, the conversion device will need to add a large amount of water vapor, resulting in higher energy consumption and investment. Utility Model Content

[0005] The technical problem to be solved by the present invention is that the biomass gasification system with a downstream conversion device in the prior art uses a waste heat boiler process with high energy consumption. A biomass fluidized bed gasification system suitable for the downstream conversion device is provided. The system of the present invention eliminates the need to supplement water vapor for the downstream conversion device, saving consumption and investment.

[0006] The utility model solves the above technical problems through the following technical solutions:

[0007] The utility model proposes a biomass fluidized bed gasification system suitable for a downstream conversion device, which comprises: a fluidized bed gasifier, a cyclone separator, an oxidative cracking furnace, a venturi scrubber, a hydrocyclone separator and a water scrubber;

[0008] The fluidized bed gasifier, the cyclone separator, the oxidative cracking furnace, the Venturi scrubber, the hydrocyclone separator and the water scrubber are sequentially connected along the flow direction of the syngas to form a syngas flow route; a quenching zone is provided in the oxidative cracking furnace;

[0009] The fluidized bed gasifier comprises 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 ports, a first gasifying agent port, and a slag discharge port; the fluidizing agent port is disposed on a side of the distribution plate, the slag discharge port is disposed at the bottom of the distribution plate, the first gasifying agent port is disposed around the slag discharge port and is closer to the slag discharge port than the fluidizing agent port; the aperture of the first gasifying agent port is larger than the aperture of the fluidizing agent port;

[0010] The gasifier body is provided with a feed port, which is located above the distribution plate and tilted toward one end of the slag discharge port; all the fluidizing agent ports located directly below the feed port are tilted toward one end of the slag discharge port.

[0011] In the present invention, it can be understood that the fluidized bed gasifier is a conventional gasifier in the art for gasifying biomass raw materials to generate synthesis gas, wherein the synthesis gas generally mainly includes H2, CO, CO2, methane and some hydrocarbons.

[0012] It can be understood that when the distribution plate of the present invention is installed in the fluidized bed gasifier, the distribution plate is placed at the bottom of the fluidized bed gasifier in an inverted cone shape, that is, the end of the distribution plate with a larger diameter faces upward, and the end of the distribution plate with a smaller diameter faces downward.

[0013] The fluidized bed gasifier of the present invention arranges a fluidizing agent port on the side of the distribution plate and arranges a first gasifying agent port around the slag discharge port, thereby increasing the reaction temperature, forming a central high-temperature area, eliminating tar, and expanding the range of the central high-temperature area of ​​the gasifier. While eliminating tar, the problem of slagging in the central high-temperature area is reduced. At the same time, by arranging the fluidizing agent port inclined at one end toward the slag discharge port below the feed port, on the one hand, the material can quickly enter the high-temperature area in the center of the gasifier for reaction, and the tar above can be brought into the high-temperature area to quickly gasify the tar. On the other hand, the downwardly arranged fluidizing agent port has a certain flushing effect on the distribution plate, which can effectively prevent the slag blocks from agglomerating to form large slag blocks to block the lower slag port.

[0014] In the present invention, the inclination angle A1 of the feed port relative to the horizontal plane is preferably 30-80°, such as 45° or 60°.

[0015] In the present invention, the feed port's inclination angle A1 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. If the feed port's inclination angle (i.e., A1) is too small, large particles will fall parabolically and hit the distribution plate, preventing most particles from accelerating to the center. If the feed port's inclination angle (i.e., A1) is too large, the particles will cause increased wear on the distribution plate.

[0016] In the present invention, the distance Hf between the lower edge of the feed port and the upper edge of the distribution plate is preferably 0-Di, such as 0.48Di or 0.072Di, where Di refers to the inner diameter of the gasifier body.

[0017] In the present invention, preferably, the axis of the feed port intersects with the central axis of the gasifier body, so that the feed direction is directly opposite to the center direction of the gasifier.

[0018] In the present invention, the slag discharge port is preferably further provided with an air inlet pipe, 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.

[0019] In the present invention, the inclination angle A2 of the fluidizing agent port inclined toward one end of the slag discharge port relative to the horizontal plane is preferably 0-30°, excluding 0°, such as 15°.

[0020] In the present invention, it can be understood that, except for all the fluidizer ports located directly below the feed port, the axes of the remaining fluidizer ports may be inclined toward one end of the slag discharge port, or may be inclined toward the end away from the slag discharge port, or may be in the horizontal direction. Preferably, the axes of the remaining fluidizer ports are inclined toward the end away from the slag discharge port or in the horizontal direction; further, the chord length L2 of the area formed by all the fluidizer ports inclined toward one end of the slag discharge port is L1~10L1, where L1 is the diameter of the feed port. 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 peripheral ash to join the central high-temperature zone, competing for the gasifier, resulting in incomplete gasification.

[0021] The distribution plate is divided into a feed acceleration zone and a bed fluidization zone along its circumference. All the fluidizer ports inclined toward one end of the slag discharge port are located in the feed acceleration zone. The chord length of the feed acceleration zone is L2, and the remaining part of the fluidizer ports are located in the bed fluidization zone.

[0022] Furthermore, the inclination angle A3 of the remaining part of the fluidizer port relative to the horizontal plane is 0~45°, for example 0°, and the inclination angle A3 refers to the angle between the axis of the fluidizer port and the horizontal plane, and a positive angle refers to the horizontal upward.

[0023] In the present invention, a plurality of fluidizing agent ports are evenly distributed on the distribution plate.

[0024] Among them, the number and distribution of fluidizing agent ports are optimized according to the scale of gasification feed. Generally, there are 5 to 10 layers of fluidizing agent ports distributed in sequence from the top to the bottom of the distribution plate, and each layer includes multiple fluidizing agent ports distributed at equal intervals 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.

[0025] In the present invention, preferably, the axis of the first gasifying agent port is parallel to the central axis of the distribution plate. The gasifying agent is ejected from the first gasifying agent port to promote high-speed turbulence in the bubbling fluidized bed region, thereby enhancing mass transfer, heat transfer, and high-temperature reaction processes in the central region and upper bubbling fluidized bed region.

[0026] In the present invention, preferably, multiple, for example, three, first gasifier ports are evenly distributed along the circumference of the slag discharge port. The distance between the axis of the first gasifier 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 gasifier port will hinder the descending ash from entering the slag discharge port, resulting in poor slag discharge. If the distance is too large, unreacted carbon-containing ash may enter the slag discharge port, resulting in the discharged slag having an excessively high carbon content and wasting raw materials.

[0027] In the present invention, the slag discharge port is preferably further provided with an air inlet pipe, 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.

[0028] Preferably, the diameter of the second gasifier port is 30-70% of the diameter of the slag discharge port. More preferably, the diameter of the second gasifier port is 100-200 mm, such as 150 mm, and the diameter of the slag discharge port is 200-300 mm, such as 250 mm.

[0029] In the present invention, the diameter of the first gasifying agent port is preferably 10-200 mm, for example 80 mm.

[0030] In the present invention, the aperture of the fluidizing agent port is preferably 2-10 mm, such as 5 mm or 7 mm.

[0031] In the present invention, the inclination angle A4 of the conical surface of the distribution plate relative to the horizontal plane is preferably 30-80°, such as 45° or 60°.

[0032] In the present invention, the fluidizing agent port is used to introduce the fluidizing agent, and the first gasifying agent port is used to introduce the gasifying agent.

[0033] In the present invention, the material of the distribution plate is metal and / or non-metal refractory material.

[0034] In the present invention, the fluidizing agent port is preferably provided with a leak-proof component for preventing the ash in the furnace 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, the outer diameter of the other end of the connecting portion matches the aperture of the fluidizing agent port, the leak-proof portion is provided with a porous structure for the passage of the gasifying agent, the pore size of the porous structure is 0.1~500μm, and the connecting portion is provided with a pore structure for the passage of the fluidizing agent. The porous structure only allows the gasifying agent to pass through, and the ash is difficult to pass through, thereby preventing the ash from flowing back to the outside of the distribution plate. The connection between the leak-proof component and the fluidizing agent port is achieved by plugging the other end of the connecting portion into the fluidizing agent port.

[0035] Wherein, the leak-proof part is preferably a block, the porous structure is provided on the block, and the block is made of one or more of metal mesh, metal fiber, metal powder and ceramic.

[0036] The pore size of the porous structure is preferably 0.1-120 μm, for example 5-25 μm. If the pore size of the porous structure is too large, ash may be blocked in the porous structure. If the pore size is too small, the fluidization effect of the fluidizer may be affected.

[0037] The hole structure on the connecting portion may be conventional in the art, such as a through hole or a mesh hole.

[0038] Wherein, the connecting portion preferably includes a first support and a sleeve, the first support is provided with a support groove, the bottom of the support groove is provided with a first through hole, the leak-proof portion 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 aperture of the fluidizing agent port and smaller than the inner diameter of the support groove, the flange is located in the support groove, and the outer diameter of the other end of the sleeve matches the aperture of the fluidizing agent port. 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 port, the other end of the sleeve is inserted into the fluidizing agent port, the flange is stuck on the outer periphery of the fluidizing agent port, and the gasifying agent enters the furnace body through the second through hole, the porous structure in the leak-proof portion and the first through hole.

[0039] More preferably, the connection portion further includes a second support, which is a sleeve structure and is sleeved onto the exterior of the flange. The first support is threadedly connected to the exterior of the second support. During installation, the end of the second support can be welded to the back of the distribution plate, and the first support is threadedly connected to the second support, facilitating assembly and disassembly of the leak-proof assembly.

[0040] More preferably, the leakage prevention assembly further includes a first support member and a second support member. The first support member, the leakage prevention portion, and the second support member are sequentially arranged in the support groove from top to bottom. The first support member and the second support member are both metal mesh structures. The pore size of the metal mesh structure is preferably 0.1 to 1 mm. The first and second support members prevent the leakage prevention portion from deforming due to extrusion.

[0041] In the present invention, the biomass fluidized bed gasification system suitable for the downstream conversion device preferably also includes a slag water unit, the oxidative cracking furnace, the cyclone separator, and the water washing tower are all connected to the inlet of the slag water unit, and the slag water unit is used to collect the ash water in the oxidative cracking furnace, the cyclone separator and the water washing tower.

[0042] Further preferably, the slag-water unit, the water scrubber, and the quenching zone of the oxidative cracking furnace are sequentially connected in series to form a gray water circulation route, for returning gray water treated by the slag-water unit to the water scrubber and the oxidative cracking furnace in sequence. In this gray water circulation route, the gray water first returns to the water scrubber to separate the ash and slag from the gray water, and then returns to the quenching zone of the oxidative cracking furnace to cool and remove dust from the gas in the oxidative cracking furnace.

[0043] It is understood that the slag-water unit is a conventional device in the art for flocculation and sedimentation separation of gray water. The slag-water unit generally includes a flash tank, a settling tank, a gray water tank, and a stripping tower, which are connected in sequence. The flash tank is connected to the gray water outlet of the oxidative cracking furnace, the gray water outlet of the hydrocyclone separator, and the gray water outlet of the water scrubber, respectively. The stripping tower is connected to the gray water circulation return port of the water scrubber.

[0044] In the present invention, preferably, a dipleg device is further provided between the cyclone separator and the fluidized bed gasifier, the dipleg device being used to return fly ash to the fluidized bed gasifier for further secondary reaction. The dipleg device is conventional in the art.

[0045] In the present invention, it can be understood that the fluidized bed gasifier is generally also provided with a synthesis gas outlet, a fly ash return port and a slag discharge port. The synthesis gas outlet is connected to the synthesis gas inlet of the cyclone separator, and the fly ash return port is connected to the fly ash discharge port of the cyclone separator.

[0046] Among them, the biomass raw material inlet and the fly ash return port are preferably arranged at the lower side of the fluidized bed gasifier, the synthesis gas outlet is preferably arranged at the top of the fluidized bed gasifier, and the slag discharge port is preferably arranged at the bottom of the fluidized bed gasifier.

[0047] In the present invention, it is understood that the cyclone separator is a conventional device in the art for separating the gas, solid and liquid components of the syngas from the fluidized bed gasifier. The cyclone separator is generally provided with a syngas inlet, a syngas outlet and a fly ash outlet.

[0048] The fly ash discharge port is preferably arranged at the bottom of the cyclone separator, the synthesis gas inlet is preferably arranged at the upper side of the cyclone separator, and the synthesis gas outlet is preferably arranged at the top of the cyclone separator.

[0049] In the present invention, it is understood that the oxidative cracking furnace is a conventional device in the art for oxidizing methane and some hydrocarbons in synthesis gas to crack them into CO and H2. The provision of such an oxidative cracking furnace can increase the effective gas (H2, CO) content. The oxidative cracking furnace is generally provided with a reaction zone and a quenching zone. The quenching zone is preferably provided with a quenching ring to evenly distribute quenching water.

[0050] The oxidative cracking furnace is generally provided with a synthesis gas inlet, an ash water outlet and a synthesis gas outlet. The synthesis gas inlet is connected to the synthesis gas outlet of the cyclone separator, and the synthesis gas outlet is connected to the air inlet of the venturi scrubber.

[0051] Wherein, the grey water outlet is preferably connected to the liquid inlet of the slag water unit.

[0052] The oxidation cracking furnace is preferably provided with a grey water circulation return port, which is connected to the grey water outlet of the water scrubber. A pump is preferably provided on the connection line between the grey water circulation return port and the grey water outlet of the water scrubber.

[0053] Among them, the synthesis gas inlet is preferably arranged at the top of the oxidation cracking furnace, the ash water outlet is preferably arranged at the bottom of the oxidation cracking furnace, the synthesis gas outlet is preferably arranged at the lower side of the oxidation cracking furnace, and the ash water circulation return port is preferably arranged at the middle side of the oxidation cracking furnace.

[0054] The oxidative cracking furnace is preferably a non-catalytic oxidative cracking furnace, which can reduce catalyst deactivation or clogging caused by H2S and fly ash in the raw synthesis gas compared to a catalytic converter.

[0055] In the present 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 is generally provided with 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.

[0056] The washing liquid inlet is preferably connected to the slag water unit, so as to use the gray water returned from the slag water unit as washing liquid for the venturi scrubber.

[0057] The washing liquid inlet is preferably arranged on the side of the venturi scrubber, and the air inlet and the air outlet are preferably respectively arranged at both ends of the venturi scrubber.

[0058] In the present invention, it is understood that the hydrocyclone separator is a conventional device in the art for separating suspended material from the venturi scrubber. The hydrocyclone separator is generally provided with an air inlet, an air outlet, and a gray 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 scrubber.

[0059] Wherein, the grey water outlet is preferably connected to the liquid inlet of the slag water unit.

[0060] The air inlet is preferably arranged at the upper side of the hydrocyclone, and the air outlet and the grey water outlet are preferably arranged at the top and bottom of the hydrocyclone, respectively.

[0061] In the present invention, it is understood that the water scrubber is a conventional device in the art for scrubbing syngas. The water scrubber is generally provided with an air inlet, an air outlet, a gray water outlet, and a water inlet. The air inlet is connected to the outlet gas of the cyclone separator, and the gray water outlet is connected to the liquid inlet of the slag water unit.

[0062] Wherein, the water washing tower is preferably further provided with a grey water circulation return port, and the grey water circulation return port is connected to the liquid outlet of the slag water unit.

[0063] Wherein, the ash water outlet is preferably also connected to the ash water circulation return port of the oxidative cracking furnace.

[0064] Among them, the air outlet and the gray water outlet are preferably arranged at the top and bottom of the water washing tower respectively, the air inlet and the gray water circulation return port are preferably both arranged at the lower side of the water washing tower, and the water inlet is preferably arranged at the upper side of the water washing tower.

[0065] The biomass fluidized bed gasification system suitable for the downstream conversion device of the present invention can be used to gasify biomass. The gasification method specifically includes the following steps:

[0066] Biomass raw materials are introduced through the feed port, fluidizing agent is introduced through the fluidizing agent port, and gasifying agent is introduced through the first gasifying agent port to carry out gasification reaction. The obtained crude synthesis gas is processed in sequence through the cyclone separator, the oxidative cracking furnace, the Venturi scrubber, the hydrocyclone separator and the water scrubber.

[0067] In the present invention, when the second gasifying agent port is further included, the gasifying agent is introduced through the second gasifying agent port.

[0068] In the present invention, when the aforementioned dipleg device is adopted, the gasification method further comprises: returning the fly ash separated from the cyclone separator to the fluidized bed gasifier through the dipleg device.

[0069] In the present invention, when the aforementioned slag-water unit is used, the gasification method further comprises: 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.

[0070] In the present invention, when the aforementioned ash water circulation route is adopted, the gasification method further comprises: the liquid portion obtained by the slag water unit treatment is returned to the water washing tower for washing, and then enters the quenching zone of the oxidative cracking furnace to serve as quenching water to quench the synthesis gas.

[0071] In the present invention, when the washing liquid inlet of the venturi scrubber is connected to the slag water unit, the gasification method further comprises: using the liquid portion obtained by treatment of the slag water unit as the washing liquid of the venturi scrubber.

[0072] In the present invention, it can be understood that the fluidizing agent and the gasifying agent are conventional in the art.

[0073] 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%.

[0074] The gasifying agent may be 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 preferably 30-60%, for example 40%.

[0075] In the present 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 0.2-2 m / s, for example, 0.3 m / s; the feed rate of the gasifying agent can be 20-80 m / s, for example, 60 m / s.

[0076] In the present invention, the temperature of the gasification reaction is conventional in the art, such as 700-1300°C, for example 820°C.

[0077] In the present invention, the pressure in the fluidized bed gasifier is conventional in the art, such as 0.5 to 80 barg, for example 40 barg.

[0078] In the present invention, it can be understood that the biomass raw materials are conventional in the art, such as one or more combinations of wood, wheat, corn stalks, rice husks, and reed bamboo.

[0079] In the present invention, the maximum particle size of the biomass raw material particles is preferably <10 mm.

[0080] The positive progress effect of this utility model is:

[0081] (1) In the traditional waste heat boiler process, the water vapor content in the synthesis gas at the outlet of the water scrubber is extremely low, at about 0.02%. However, the system of the utility model adopts a quenching 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.

[0082] (2) Since biomass contains a large amount of alkali metals, if the waste heat boiler process is adopted, it is easy to cause scaling and corrosion of the waste heat boiler. However, the system of the utility model adopts a quenching process, and the alkali metals are brought into the water system by the quenching water. The concentration is very low and there will be no scaling and corrosion.

[0083] (3) Since biomass contains a large amount of chloride ions, if the waste heat boiler process is adopted, the chloride ion content at the water washing tower will be as high as 5000~10000ppm, causing serious corrosion of the water washing system pipeline. The system of the utility model adopts a quenching 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.

[0084] (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 quenching process, and the slag and fly ash are brought to the slag water system for treatment by the quenching water, so there is no blockage problem.

[0085] (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. The effective gas in the synthesis gas can reach more than 65%, which greatly improves the yield of effective gas from biomass gasification. 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 between 50 and 100 g / Nm 3 , methane is above 10%, resulting in a low effective gas content in the synthesis gas, below 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 This is a structural diagram of a biomass gasification system according to an embodiment of the present utility model.

[0087] Figure 2 This is a schematic diagram of the distribution plate structure described in Example 1 of the present utility model.

[0088] Figure 3 This is a partial structural diagram of the fluidized bed gasifier described in Example 1 of the present utility model.

[0089] Figure 4 This is a positional relationship diagram of the first gasifying agent port and the slag discharge port in the fluidized bed gasifier described in Example 1 of the present utility model.

[0090] Figure 5 It is a structural schematic diagram of the leakage-proof component recorded in Example 1 of the present utility model.

[0091] Description of reference numerals:

[0092] Fluidized bed gasifier 1

[0093] Gasifier 101

[0094] Feed port 1011

[0095] Distribution plate 102

[0096] Fluidizer port 1021

[0097] First gasifying agent port 1022

[0098] Slag discharge port 1023

[0099] Second gasifying agent port 1024

[0100] Feed acceleration zone S1

[0101] Bed fluidization zone S2

[0102] Leakage prevention component 103

[0103] The first support 1031

[0104] First through hole 10311

[0105] Limiting step surface 10312

[0106] Second support 1032

[0107] Casing 1033

[0108] First support member 1034

[0109] Second support member 1035

[0110] Leak-proof part 1036

[0111] Cyclone separator 2

[0112] Oxidation cracking furnace 3

[0113] Venturi scrubber 4

[0114] Hydrocyclone 5

[0115] Water washing tower 6

[0116] Slag water unit 7

[0117] leg device 8

[0118] pump 9 DETAILED DESCRIPTION

[0119] The utility model will be further illustrated by way of examples below, but the utility model is not limited to the scope of the examples described.

[0120] Example 1

[0121] The embodiment discloses a fluidized bed gasification furnace, as shown in the figure, which comprises a gasification furnace body 101 and a distribution plate 102 in the gasification furnace body 101. Figures 2-5

[0122] The gasification furnace body 101 is provided with two feed inlets 1011, the axis of the feed inlet 1011 intersects with the central axis of the gasification furnace body 101, so that the feeding direction is directly opposite the center direction of the gasification furnace body 101.

[0123] 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 0.18 m, the inner diameter Di of the gasification furnace body 101 is 3.3 m, and the total height is 25 m. 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°.

[0124] The inclination angle 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.

[0125] The distribution plate 102 is provided with a plurality of fluidizing agent ports 1021, first gasification agent ports 1022 and slag discharge ports 1023, the first gasification agent port 1022 is provided with a pipeline, the inner diameter of the pipeline is 80 mm, and the pore size of the fluidizing agent port 1021 is 5 mm.

[0126] The distribution plate 102 is in the shape of a conical bucket, and the distribution plate is provided with 5 layers of fluidizing agent ports 1021, the spacing between two adjacent layers along the axial direction of the distribution plate is 300 mm, and the number of fluidizing agent ports of each layer from top to bottom is 82, 71, 52, 44 and 22 respectively, and the fluidizing agent ports of each layer are distributed equidistantly along the circumferential direction of the distribution plate 102.

[0127] ​The distribution plate 102 is divided circumferentially into a feed acceleration zone S1 and a bed fluidization zone S2. Each feed inlet 1011 corresponds to a feed acceleration zone S1. The diameter L1 of the feed inlet 1011 is 100 mm, and the chord length L2 of the feed acceleration zone S1 is 300 mm. The axis of the fluidizer inlet 1021 in the feed acceleration zone S1 is tilted toward one end of the slag discharge port 1023, with an inclination angle A2 of -15°. The axis of all fluidizer inlets 1021 in the bed fluidization zone S2 is tilted at an angle A3 of 0° relative to the horizontal plane, indicating a horizontal orientation.

[0128] The slag discharge port 1023 is set at the bottom of the distribution plate 102. There are three first gasifier ports 1022. The three first gasifier ports 1022 are arranged at equal intervals around the slag discharge port 1023. The distance between the axis of the first gasifier port and the axis of the slag discharge port is 300 mm. The axis of the first gasifier port 1022 is parallel to the axis of the distribution plate 102 and is in the vertical direction. A gasifier feed pipe is provided in each first gasifier port 1022. A lower slag pipe is provided in the slag discharge port 1023. A gasifier feed pipe is sleeved in the lower slag pipe as the second gasifier port 1024. The pipe diameter is 150 mm. The annular gap formed between the lower slag pipe and the gasifier feed pipe is the slag discharge area.

[0129] The fluidizing agent inlet 1021 is equipped with a leak-proof assembly 103, located on the back of the distribution plate 102. This assembly 103 includes a leak-proof portion 1036 and a connecting portion. The leak-proof portion 1036 is a plate structure made of metal fiber. The plate is provided with a porous structure for the gasifying agent to pass through. The pore size of the porous structure is 5 to 25 μm. The connecting portion is provided with a hole structure for the gasifying agent to pass through.

[0130] The connection portion 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 is provided with a support groove, the bottom of which is provided with a first through-hole 10311. The first support member 1034, the leak-proof portion 1036, and the second support member 1035 are sequentially arranged in the support groove from top to bottom. A flange is provided at one end of the sleeve 1033. The outer diameter of the flange is larger than the aperture of the fluidizer port 1021 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 1033 matches the aperture of the fluidizer port 1021. The second support 1032 is a sleeve structure made of metal. The second support 1032 is sleeved onto the outside of the flange, and the first support 1031 is connected to the outside of the second support 1032 via threads.

[0131] 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 to avoid excessive screwing and squeezing of the leak-proof portion 1036.

[0132] 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 portion 1036 , the thickness of the second support member 1035 and the thickness of the flange of the sleeve 1033 .

[0133] The sleeve 1033 is a ceramic sleeve with a length of 100 mm and an inner diameter of 5.0 mm. The wall thickness of the end of the sleeve 1033 where no flange is provided is 1.5 mm.

[0134] The first support member 1034 and the second support member 1035 are both made of a wire mesh structure. The aperture of the wire mesh is about 0.5 mm, and the diameter of the skeleton wire of the wire mesh is 0.2 mm.

[0135] During installation, the first support member 1034, the leak-proof portion 1036, and the second support member 1035 are installed in 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 end of the sleeve 1033 is inserted into the fluidizing agent port 1021 and, through the flange of the sleeve 1033, is clamped to the distribution plate 102 on the outer periphery of the fluidizing agent port 1021. The first support 1031 is connected to the second support 1032 via threads. The gasifying agent enters the furnace body through the second through-hole 10311, the porous structure of the leak-proof portion, and the tube hole of the sleeve 1033.

[0136] Example 2

[0137] 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.

[0138] The fluidized bed gasification furnace 1 is the fluidized bed gasification furnace described in Example 1.

[0139] The gasifier body 101 is also provided with a synthesis gas outlet, a fly ash return port and a slag discharge port. The synthesis gas outlet is arranged at the top of the gasifier body 101, the slag discharge port is arranged at the bottom of the gasifier body 101, and the fly ash return port is arranged at the lower side of the gasifier body 101.

[0140] The cyclone separator 2 is used to separate the solid and liquid parts in the synthesis gas coming out of the fluidized bed gasifier; wherein, the cyclone separator 2 is provided with a synthesis gas inlet, a synthesis gas outlet and a fly ash discharge outlet, the fly ash discharge outlet is arranged at the bottom of the cyclone separator 2, the synthesis gas inlet is arranged at the upper side of the cyclone separator 2, and the synthesis gas outlet is arranged at the top of the cyclone separator 2.

[0141] A feed leg device 8 is provided at the bottom of the cyclone separator, which is connected between the fly ash discharge port of the cyclone separator 2 and the fly ash return port of the gasifier furnace body 101, and is used to return the fly ash to the fluidized bed gasifier 1 for further secondary reaction.

[0142] The oxidative cracking furnace 3 includes a reaction zone and a quenching zone. The quenching zone is provided with a quenching ring for evenly distributing quenching water. The oxidative cracking furnace 3 is provided with a synthesis gas inlet, an ash water outlet, a synthesis gas outlet and an ash water circulation return port. The synthesis gas inlet is arranged at the top of the oxidative cracking furnace 3, the ash water outlet is arranged at the bottom of the oxidative cracking furnace 3, the synthesis gas outlet is arranged at the lower side of the oxidative cracking furnace 3, and the ash water circulation return port is arranged at the middle side of the oxidative cracking furnace 3.

[0143] The venturi scrubber 4 is used to remove dust from the gas coming out of the oxidative cracking furnace. The venturi scrubber 4 is provided with an air inlet, a washing liquid inlet and an air outlet. The washing liquid inlet is arranged on the side of the venturi scrubber 4, and the air inlet and the air outlet are respectively arranged at both ends of the venturi scrubber 4.

[0144] The hydrocyclone separator 5 is used to separate the suspended materials coming out of the venturi scrubber 4. The hydrocyclone separator is provided with an air inlet, an air outlet and a gray water outlet. The air inlet is provided on the upper side of the hydrocyclone separator, and the air outlet and the gray water outlet are provided at the top and bottom of the hydrocyclone separator 5 respectively.

[0145] The water scrubber 6 is used to further wash the synthesis gas. The water scrubber 6 is provided with an air inlet, an air outlet, a gray water outlet, a gray water circulation return port and a water inlet. The air outlet and the gray water outlet are respectively arranged at the top and bottom of the water scrubber 6, the air inlet and the gray water circulation return port are both arranged at the lower side of the water scrubber 6, and the water inlet is arranged at the upper side of the water scrubber 6.

[0146] The slag water unit 7 is used to perform flocculation and sedimentation separation on the grey water. The slag water unit 7 includes a flash tank, a sedimentation tank, a grey water tank and a stripping tower which are connected in sequence.

[0147] The synthesis gas outlet of the gasifier body 101 is connected to the synthesis gas inlet of the cyclone separator 2, the synthesis gas outlet of the cyclone separator 2 is connected to the synthesis gas inlet of the oxidative cracking furnace 3, the synthesis gas outlet of the oxidative cracking furnace 3 is connected to the air inlet of the venturi scrubber, the air outlet of the venturi scrubber is connected to the air inlet of the cyclone separator 5, the washing liquid inlet of the venturi scrubber 4 is connected to the stripping tower outlet of the slag water unit 7, the returned ash water is used as the washing liquid of the venturi scrubber 4, the air outlet of the cyclone separator 5 is connected to the air inlet of the water washing tower 6, forming a synthesis gas flow route.

[0148] The fly ash return port of the gasifier shaft 101 is connected to one end of the dipleg device 8 , and the other end of the dipleg device 8 is connected to the fly ash discharge port of the cyclone separator 2 .

[0149] The flash tank in the slag-water unit 7 is connected to the ash water outlet of the oxidative cracking furnace 3, the ash water outlet of the hydrocyclone 5, and the ash water outlet of the water scrubber 6, respectively. The stripping tower in the slag-water unit 7 is connected to the ash water return port of the water scrubber 6, and the ash water outlet of the water scrubber 6 is connected to the ash water return port of the oxidative cracking furnace 3, forming a ash water circulation route. A pump 9 is installed on the connecting line between the ash water return port of the oxidative cracking furnace 3 and the ash water outlet of the water scrubber 6. The ash water first returns to the water scrubber 6 to separate the ash from the ash water, and then returns to the quenching zone of the oxidative cracking furnace 3 to cool and remove dust from the gas in the oxidative cracking furnace 3.

[0150] Example 3

[0151] 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.

[0152] The gasification method specifically includes the following steps:

[0153] Biomass raw materials are introduced through the feed port 1011, a fluidizing agent is introduced through the fluidizing agent port 1021, and a gasifying agent is introduced through the first gasifying agent port 1022 and the second gasifying agent port 1024 to carry out a gasification reaction. The resulting crude synthesis gas is sequentially processed through the cyclone separator 2, the oxidative cracking furnace 3, the venturi scrubber 4, the hydrocyclone separator 5 and the water scrubber 6;

[0154] During the treatment process, the fly ash separated from the cyclone separator 2 is returned to the fluidized bed gasifier 1, and the ash water coming out of 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 obtained after being treated 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 to serve as quenching water to quench the synthesis gas.

[0155] The raw material is biomass pellets after granulation. The biomass is one or more combinations of wheat, corn straw, rice husk and reed. The maximum particle size of the pellets is <10mm and the external water content is <4%. The feed rate is 50t / h, the feed is at room temperature, the gasification pressure is 40barg, and the gasification temperature is 820℃. The fluidizing agent and gasifying agent are both a mixture of oxygen and water vapor, wherein the oxygen content in the gasifying agent is 40%, and the gasifying agent feed speed is 60m / s; the oxygen content in the fluidizing agent is 10%, and the fluidizing agent feed speed is 0.3m / s. The total flow rate of the gasifying agent and the total flow rate of the fluidizing agent is 15t / h, wherein the total flow rate of the gasifying agent is 8.6t / h, the total flow rate of the fluidizing agent is 6.4t / h, and the volume of the fluidized bed gasifier is 220m 3 .

[0156] The system operation time of this embodiment is 200 days.

[0157] Implementation effect:

[0158] The residence time of the biomass particles in the gasifier body 101 is greater than 20 seconds, and the outlet of the fluidized bed gasifier 1 does not contain tar.

[0159] After quenching, the water-vapor ratio of the synthesis gas reaches about 0.8, saving energy consumption of the downstream conversion unit.

[0160] After quenching, the chloride ion concentration in the gray water is reduced to below 50~500ppm, and the alkali metal concentration is trace.

[0161] The components of the synthesis gas coming out of the water scrubber 6 were monitored, and the effective gas content in the synthesis gas was >65%.

Claims

1. A biomass fluidized bed gasification system suitable for a downstream conversion device, characterized in that: It includes: fluidized bed gasifier, cyclone separator, oxidative cracking furnace, venturi scrubber, hydrocyclone separator and water scrubber; The fluidized bed gasifier, the cyclone separator, the oxidative cracking furnace, the Venturi scrubber, the hydrocyclone separator and the water scrubber are sequentially connected along the flow direction of the syngas to form a syngas flow route; a quenching zone is provided in the oxidative cracking furnace; The fluidized bed gasifier comprises 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 ports, a first gasifying agent port, and a slag discharge port; the fluidizing agent port is disposed on a side of the distribution plate, the slag discharge port is disposed at the bottom of the distribution plate, the first gasifying agent port is disposed around the slag discharge port and is closer to the slag discharge port than the fluidizing agent port; the aperture of the first gasifying agent port is larger than the aperture of the fluidizing agent port; The gasifier body is provided with a feed port, which is located above the distribution plate and tilted toward one end of the slag discharge port; all the fluidizing agent ports located directly below the feed port are tilted toward one end of the slag discharge port.

2. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 1, characterized in that: The fluidized bed gasifier satisfies one or more of the following conditions: ① The inclination angle A1 of the feed port relative to the horizontal plane is 30-80°; ② The inclination angle A1 of the feed port 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; ③ The distance Hf between the lower edge of the feed port and the upper edge of the distribution plate is 0~Di, where Di refers to the inner diameter of the gasifier body; ④ The axis of the feed port intersects with the central axis of the gasifier body; ⑤ The inclination angle A2 of the fluidizing agent port inclined toward one end of the slag discharge port relative to the horizontal plane is 0° to 30°, excluding 0°; ⑥ The slag discharge port is 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; the diameter of the second gasifying agent port accounts for 30-70% of the diameter of the slag discharge port, and the diameter of the second gasifying agent port is 100-200 mm; ⑦ The chord length of the area formed by all the fluidizing agent ports inclined toward one end of the slag discharge port is L2 = L1 ~ 10L1, where L1 is the diameter of the feed port; ⑧ Except for all the fluidizing agent ports located directly below the feed port, the axes of the remaining fluidizing agent ports are inclined toward the end away from the slag discharge port or along the horizontal direction; the inclination angle A3 of the remaining fluidizing agent ports relative to the horizontal plane is 0~45°.

3. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 1, characterized in that: The fluidized bed gasifier satisfies one or more of the following conditions: ① The aperture of the fluidizing agent port is 2~10mm; ② The fluidizing agent ports are evenly distributed on the distribution plate; 5 to 10 layers of fluidizing agent ports are sequentially distributed from the top to the bottom of the distribution plate, and each layer of fluidizing agent ports includes multiple fluidizing agent ports distributed at equal intervals 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 100 to 300 mm; ③ The axis of the first gasifying agent port is parallel to the central axis of the distribution plate; ④ The diameter of the first gasifying agent port is 10-200 mm; ⑤ There are multiple first gasifying agent ports 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 200-500 mm; ⑥ The inclination angle A4 of the conical surface of the distribution plate relative to the horizontal plane is 30~80°.

4. The biomass fluidized bed gasification system suitable for a downstream conversion device according to any one of claims 1 to 3, characterized in that: The fluidizing agent port is provided with a leak-proof component, which 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 port. 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 pore structure for the fluidizing agent to pass through.

5. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 4, characterized in that: The anti-leakage component meets one or more of the following conditions: ① The leak-proof part is a block, and the porous structure is provided on the block; ② The pore size of the porous structure is 0.1~120μm.

6. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 4, characterized in that: The connecting portion includes a first support and a sleeve, a support groove is provided on the first support, a first through hole is provided at the bottom of the support groove, the leak-proof portion is provided in the support groove, a flange is provided at one end of the sleeve, the outer diameter of the flange is larger than the aperture 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 aperture of the fluidizing agent port, and the first through hole and the tube hole of the sleeve form the hole structure.

7. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 6, characterized in that: The connecting portion 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 connected to the outside of the second support by a thread. The leakage-proof component also includes a first support member and a second support member. The first support member, the leakage-proof part and the second support member are arranged in the support groove from top to bottom in sequence. The first support member and the second support member are both metal mesh structures; the pore size of the metal mesh structure is preferably 0.1~1mm.

8. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 1, characterized in that: The biomass fluidized bed gasification system suitable for the downstream conversion device also includes a slag water unit. The oxidative cracking furnace, the cyclone 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 in the oxidative cracking furnace, the cyclone separator, and the water washing tower.

9. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 8, characterized in that: The biomass fluidized bed gasification system suitable for the downstream conversion device meets one or more of the following conditions: ① The slag water unit, the water scrubber, and the quenching zone of the oxidative cracking furnace are connected in series to form a gray water circulation route, which is used to return the gray water treated by the slag water unit to the water scrubber and the oxidative cracking furnace in sequence; ② The slag 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 cyclone separator, and the ash water outlet of the water scrubber respectively. The stripping tower is connected to the ash water circulation return port of the water scrubber; ③ The washing liquid inlet of the venturi scrubber is connected to the slag water unit, so as to use the gray water returned from the slag water unit as the washing liquid of the venturi scrubber.

10. The biomass fluidized bed gasification system suitable for a downstream conversion device according to claim 1, characterized in that: A dipleg device is further provided between the cyclone separator and the fluidized bed gasifier, and the dipleg device is used to return fly ash to the fluidized bed gasifier.

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