Biomass gasification system

Abstract

The utility model relates to a biomass gasification system which comprises a pressurized feeding unit, a fluidized bed gasification unit, a deslagging unit, an entrained-flow bed high-temperature cracking unit, a synthesis gas washing unit, a slag water unit and a gasifying agent conveying unit, the fluidized bed gasification unit comprises a fluidized bed gasification furnace and a high-temperature cyclone separator; the fluidized bed gasification furnace is connected with the pressurized feeding unit, the gasifying agent conveying unit, the high-temperature cyclone separator and the deslagging unit; the entrained-flow bed high-temperature cracking unit comprises an entrained-flow bed high-temperature cracking furnace, and the entrained-flow bed high-temperature cracking furnace is connected with a high-temperature cyclone separator, a gasifying agent conveying unit, a synthesis gas washing unit and a slag water unit. Compared with the prior art, the fluidized bed entrained-flow bed has the advantages of a fluidized bed and an entrained-flow bed, and has the characteristics of wide raw material applicability, high effective gas content, no tar, low energy consumption and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of biomass gasification to produce synthesis gas, in particular to a biomass gasification system. Background Art

[0002] Biomass gasification technologies are mainly divided into fixed-bed gasification, fluidized-bed gasification, and entrained-flow gasification. Patent CN202898353U discloses a multi-stage fixed-bed biomass gasifier, which includes a longitudinally arranged furnace body, a conical tail ash section at the bottom, and at least two gas-producing sections above the tail ash section. Patent CN101560411A discloses an updraft household biomass gasifier, which is a vertical cylindrical structure. Its structure consists of an upper retorting chamber, a middle main gasification chamber, and a lower ash chamber, each section separated by a heat storage grid and a heat storage grate. The main gasification chamber is surrounded by radiant cylinders. Patent CN108559548A discloses a biomass fluidized-bed gasifier, which includes a furnace body and pipelines. The upper middle and top parts of the outer wall of the furnace body are wrapped with an insulation layer. The outer wall of the furnace body is covered with a water jacket from the upper middle to the bottom, and the upper part of the water jacket is provided with a steam outlet. The energy generated during the gasification process is partially recovered through heat exchange with the cooling water in the water jacket. Patent CN113105917A discloses a biomass fluidized bed multi-stage gasifier. The internal structure of the gasifier consists of a lower high-temperature combustion chamber, an intermediate high-temperature pyrolysis chamber, and an upper steam gasification chamber. It uses biomass as raw material to produce high-calorific value gasification gas and high-quality biochar / activated carbon.

[0003] The gas components of the above patent contain a large amount of tar and methane, which can easily clog downstream equipment and lead to a reduction in the content of effective gases CO and H2, making it unsuitable for the needs of downstream chemical product synthesis.

[0004] Biomass itself has low energy density, high volatile matter content, high oxygen content, high alkali metal content, high chloride ion content, and its ash composition is mainly SiO2. Its properties are very different from those of coal, specifically:

[0005] (1) Fixed-bed gasification technology has high requirements for the strength and thermal stability of raw materials. The biomass gasification process results in unstable bed layers, oxygen bias in the furnace, overheating at the gasifier outlet, and the presence of tar, phenol and other substances in the wastewater, making it difficult to treat. The gasifier outlet gas contains a large amount of tar and methane. Tar condensation in the downstream will block the pipeline, and the presence of methane will reduce the effective gas CO and H2, which is not conducive to downstream chemical synthesis.

[0006] (2) Fluidized bed gasification has relatively broad requirements for raw materials, with no requirements for strength, thermal stability, pulverization, or viscosity-temperature characteristics. However, currently operating fluidized bed biomass gasification units primarily use atmospheric air gasification, primarily for boiler combustion and power generation, and are not suitable for the needs of chemical product synthesis. Furthermore, simple fluidized bed gasification also has problems such as high tar and methane content and low carbon conversion rate.

[0007] (3) Entrained-flow gasification has a high temperature, and the synthesis gas contains no tar and has a very low methane content. However, it requires a micron-level raw material particle size, which makes pretreatment complex and energy consumption extremely high, making it difficult to ensure stable raw material transportation. The ash-slag has a high silicon-aluminum ratio, making it difficult to achieve "slag-to-slag" and ensuring long-term operation of the gasifier.

[0008] Therefore, for the synthesis of sustainable aviation fuel and green methanol and other chemical products, it is urgent to develop an economical and reliable biomass gasification technology. Utility Model Content

[0009] The purpose of the utility model is to provide a biomass gasification system that couples the advantages of a fluidized bed and an entrained bed.

[0010] The purpose of the utility model can be achieved by the following technical solutions: A biomass gasification system includes a pressurized feeding unit, a fluidized bed gasification unit, a slag removal unit, an entrained bed high-temperature cracking unit, a synthesis gas washing unit, a slag-water unit and a gasifying agent conveying unit;

[0011] The fluidized bed gasification unit includes a fluidized bed gasification furnace and a high-temperature cyclone separator, and the fluidized bed gasification furnace is connected to a pressurized feeding unit, a gasifying agent conveying unit, a high-temperature cyclone separator and a slag discharge unit;

[0012] The entrained flow high temperature cracking unit comprises an entrained flow high temperature cracking furnace, which is connected to a high temperature cyclone separator, a gasifying agent conveying unit, a synthesis gas washing unit and a slag water unit.

[0013] The utility model combines the advantages of fluidized bed and entrained bed - wide adaptability of raw materials, simple feeding and no tar; and overcomes the defects of both - the presence of tar in fluidized bed gasification and the difficulty of entrained bed pulverization; it has the characteristics of wide raw material applicability, high effective gas content, no tar and low energy consumption.

[0014] Preferably, the pressurized feeding unit comprises a biomass bin, a biomass locking hopper and a biomass sending hopper connected in sequence;

[0015] The biomass locking hopper is connected to the pressurized gas delivery unit, and the biomass sending hopper is connected to the fluidized bed gasification unit.

[0016] Preferably, the fluidized bed gasifier is provided with a biomass feed inlet, a gasifying agent feed inlet, a synthesis gas outlet, a fly ash return port and a slag discharge port;

[0017] The biomass feed port is connected to the pressurized feed unit, the gasifying agent feed port is connected to the gasifying agent conveying unit, the synthesis gas outlet and the fly ash return port are both connected to the high-temperature cyclone separator, and the slag discharge port is connected to the slag discharge unit.

[0018] Preferably, the slag discharge unit comprises a slag discharge buffer tank, a slag lock bucket and a slag bin connected in sequence;

[0019] The slag discharge buffer tank is connected to the bottom of the fluidized bed gasification furnace.

[0020] Preferably, the entrained flow high temperature cracking furnace comprises a burner, a radiation waste heat boiler and a quenching module arranged in sequence from top to bottom;

[0021] The burner is connected to the high-temperature cyclone separator and the gasification agent delivery unit, the radiation waste heat boiler is connected to the boiler water delivery unit and the steam output unit, and the quenching module is connected to the synthesis gas washing unit and the slag water unit.

[0022] Further preferably, the burner includes a premixing chamber, a synthesis gas channel, an oxygen channel, a purge gas channel, and inner / middle / outer cooling water channels.

[0023] Further preferably, the synthesis gas channel is connected to the high-temperature cyclone separator, the oxygen channel is connected to the gasification agent delivery unit, the purge gas channel is connected to the protective gas source, the synthesis gas channel, the oxygen channel, and the purge gas channel are all connected to the premixing chamber, and the internal / middle / external cooling water channels are connected to the burner cooling water pipeline.

[0024] Further preferably, the radiation waste heat boiler includes a water tube and a membrane wall.

[0025] More preferably, the water pipe is connected to the boiler water delivery unit and the steam output unit, and the membrane wall is arranged in the lower part of the fluidized flow high-temperature cracking furnace and is connected to the boiler water pipe.

[0026] Further preferably, the quenching module includes a quenching ring, a downcomer, an upcomer and a slag pool.

[0027] More preferably, the downcomer and the riser are coaxially arranged from inside to outside, the quenching ring is arranged above the downcomer and the riser, the slag pool is arranged below the downcomer and the riser, and is connected to the slag water unit.

[0028] In the present invention, the working principle of the fluidized-flow high-temperature cracking furnace is as follows: the crude synthesis gas after dust removal by the high-temperature cyclone separator enters the premixing chamber purged with protective gas through the synthesis gas channel, and is mixed with the gasifying agent introduced through the oxygen channel to undergo cracking reaction. During the reaction, burner cooling water is introduced through the internal / middle / external cooling water channels to cool the burner. The high-temperature cracking gas after the cracking reaction enters the radiation waste heat boiler along the furnace, is cooled after membrane wall heat exchange, and at the same time, the water in the water pipe is heated to convert the boiler water into high-temperature and high-pressure steam. The cracking gas after heat recovery by the radiation waste heat boiler enters the quenching module along the furnace, is cooled and preliminarily dusted in the quenching module, and then enters the synthesis gas washing unit. The quenching water enters the downcomer through the quenching ring to directly contact and cool the cracking gas, and then enters the slag water unit through the slag pool.

[0029] Further preferably, the synthesis gas scrubbing unit comprises a venturi scrubber, a hydrocyclone separator and a water scrubber connected in sequence;

[0030] The venturi scrubber is connected to the quenching module, the hydrocyclone is connected to the slag-water unit, and the water scrubber is connected to the quenching module, the slag-water unit and the synthesis gas output unit.

[0031] More preferably, the water scrubber is provided with a synthesis gas inlet, a quenching water return port, a slag water outlet and an ash water inlet;

[0032] The synthesis gas inlet is connected to the hydrocyclone separator, the quenching water return port is connected to the entrained flow high temperature cracking furnace, and the slag water outlet and the ash water inlet are both connected to the slag water unit.

[0033] Preferably, the slag water unit is provided with a black water inlet, a wash water inlet and a grey water outlet;

[0034] The black water inlet is connected to the entrained flow high temperature cracking furnace, and the washing water inlet and the gray water outlet are both connected to the synthesis gas washing unit.

[0035] Further preferably, the slag water unit includes a flash tank, a settling tank, an ash water tank, a stripping tower and a slurry dehydrator.

[0036] More preferably, the flash tank is provided with a black water inlet and a wash water inlet, and is connected to the sedimentation tank, the sedimentation tank is connected to the gray water tank, the gray water tank is connected to the stripping tower, and the stripping tower is provided with a gray water outlet.

[0037] In the utility model, the working principle of the slag water unit is as follows: the black water and washing water produced by the entrained flow high temperature cracking furnace and the synthesis gas washing unit enter the flash tank for flash cooling, the black water after flash cooling enters the sedimentation tank for sedimentation and clarification, and then enters the gray water tank, the gray water in the gray water tank is returned to the synthesis gas washing unit for recycling after steam stripping, and the filter slurry at the bottom of the sedimentation tank is dehydrated by the dehydrator to form a filter cake and sent out of the boundary area.

[0038] Preferably, the gasifying agent delivery unit comprises a storage tank storing pure oxygen / oxygen-enriched oxygen / air and steam / CO2 and a delivery pipeline.

[0039] Preferably, the fluidized bed gasification furnace, the high-temperature cyclone separator, and the entrained flow high-temperature cracking furnace are all provided with refractory linings.

[0040] Preferably, the slag buffer tank and slag lock hopper are water-jacketed structures.

[0041] Preferably, the pressure of the fluidized bed gasification unit is 50 kpag to 8 MPa(g), and the temperature is 700°C to 950°C.

[0042] Preferably, the pressure of the entrained flow high temperature cracking unit is 50 kpag to 8 MPa(g), and the temperature is 1000°C to 1300°C.

[0043] A biomass gasification method, performed using the above system, comprises the following steps:

[0044] (1) The biomass is pressurized by the pressurized feeding unit and then transported to the fluidized bed gasification unit;

[0045] (2) In the fluidized bed gasifier, biomass reacts with gasifying agent to produce synthesis gas, which is then removed by high-temperature cyclone separator to form crude synthesis gas. The bottom slag is cooled and decompressed by the slag discharge unit and then discharged.

[0046] (3) The crude synthesis gas is mixed with the gasifying agent in the entrained flow high-temperature cracking furnace, and the tar and methane cracking reaction occurs. The tar and methane in the crude synthesis gas are converted into effective gases CO and H2 at high temperature;

[0047] (4) The high-temperature cracking gas after the cracking reaction is washed by the synthesis gas washing unit to form dust-removed synthesis gas, and the black water produced by washing enters the slag water unit.

[0048] Preferably, the biomass gasification method specifically comprises the following steps:

[0049] S1: The biomass is pressurized by the pressurized feeding unit and then transported to the fluidized bed gasification unit;

[0050] S2: In the fluidized bed gasifier, biomass reacts with gasifying agent to produce synthesis gas, which is then removed by high-temperature cyclone separator to form crude synthesis gas. The bottom slag is cooled and decompressed by the slag discharge unit before being discharged.

[0051] S3: The crude synthesis gas and the gasifying agent are evenly mixed at the burner of the entrained flow high-temperature cracking furnace, and the tar and methane cracking reaction occurs. The temperature is raised to 1000℃~1300℃, and the tar and methane in the crude synthesis gas are converted into effective gases CO and H2 at high temperature;

[0052] S4: The high-temperature cracked gas after the cracking reaction passes through the radiation waste heat boiler to convert the boiler water into high-temperature and high-pressure steam. After recovering the heat, it enters the quenching module to be cooled to 200℃~250℃ and washed to remove most of the ash;

[0053] S5: The quenched synthesis gas is washed by the venturi scrubber, hydrocyclone separator and water scrubber to form dust-free synthesis gas, which is then sent out of the system;

[0054] S6: The black water produced by the quenching module, hydrocyclone separator and water scrubber enters the slag water unit for flash evaporation, cooling, sedimentation and clarification. The solid ash is dehydrated and discharged outside the boundary. The clarified ash water returns to the synthesis gas scrubbing unit for recycling.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] 1. The present invention provides a system for producing high-quality syngas from biomass with stable operation and economical cost.

[0057] 2. The utility model provides a pressurized biomass gasification system that couples a fluidized bed with an entrained flow bed. It combines the advantages of a fluidized bed and an entrained flow bed while overcoming the disadvantages of both. It has the characteristics of wide raw material applicability, high effective gas content, no tar, and low energy consumption.

[0058] 3. The raw materials of this utility model are widely adaptable. Straw, fruit shells, rice husks, furfural residue, agricultural product processing residues, forests, organic solid waste, and domestic garbage can all be used as raw materials. There are no special requirements for the ash content, ash melting point, volatile matter content, fixed carbon content, drop strength, thermal stability, raw material particle size distribution, viscosity-temperature characteristics, etc. of the biomass.

[0059] 4. The utility model has a high carbon conversion rate. The carbon-containing fly ash produced by the gasification system is further gasified in the high-temperature cracking furnace, making the carbon conversion rate >98%.

[0060] 5. The quality of the synthesis gas produced by the utility model is high. A high-temperature cracking furnace is used to further convert the synthesis gas produced by the gasification furnace, and the tar and methane in the synthesis gas are cracked at high temperature; the burner ensures that the synthesis gas produced by the gasification furnace is evenly mixed with oxygen, avoiding the local high temperature and short-circuiting problems of tar and methane caused by point-like oxygen supply, so that all tar is converted, and the conversion rate of methane is >98%. The existing synthesis gas tar and methane purification generally adopts water washing or catalytic methods. Water washing will produce a large amount of tar-containing wastewater, and the catalytic method will cause the catalyst to be blocked and poisoned. The dust content of the synthesis gas in the out-of-bounds area of ​​the utility model is <1 mg / Nm 3 , which solved the blockage problem of downstream devices.

[0061] 6. This utility model boasts high energy recovery and operational reliability. The use of a radiant waste heat boiler coupled with a quenching system simultaneously generates large amounts of high-temperature, high-pressure steam while cooling the syngas, improving energy recovery. The complex syngas cooler and expensive dust collector system are eliminated, while the alkali metal is simultaneously solidified, preventing alkali metal and fly ash contamination of the syngas cooler and downtime caused by dust accumulation, wear, and corrosion in the syngas cooler and dust collector. The high water circulation rate in the quenching process's water scrubber keeps the chloride ion concentration in the scrubbing system below 25 ppm, preventing corrosion of piping and equipment caused by excessive chloride ion concentrations.

[0062] 7. This utility model has low comprehensive energy consumption. It adopts pressurized pure oxygen gasification, which reduces the content of impurity gases in the synthesis gas, increases the synthesis gas pressure, reduces the load on the purification system, and reduces the power consumption of synthesis compression.

[0063] 8. This utility model is environmentally friendly. The synthesis gas contains no tar components, the slag is discharged by dry method, and the wastewater contains no tar, phenol and other difficult-to-treat substances.

[0064] 9. This utility model can reduce alkali metal radiation, reduce the risk of corrosion, scaling and clogging, and is conducive to the long-term stable operation of the system.

[0065] 10. The utility model has low biomass and oxygen consumption per unit effective gas, low investment, economical synthesis gas cost, and high product quality. It can be used to produce sustainable aviation fuel, green methanol and other high-end green chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 This is a schematic structural diagram of the biomass gasification system of the utility model;

[0067] In the figure: 1-pressurized feeding unit, 11-biomass bin, 12-biomass lock hopper, 13-biomass sending hopper, 2-fluidized bed gasification unit, 21-fluidized bed gasifier, 22-high-temperature cyclone separator, 3-slag discharge unit, 31-slag discharge buffer tank, 32-slag lock hopper, 33-slag bin, 4-entrained flow high-temperature cracking unit, 41-entrained flow high-temperature cracking furnace, 411-burner, 412-radiation waste heat boiler, 413-quenching module, 5-synthesis gas washing unit, 51-Venturi scrubber, 52-cyclone separator, 53-water washing tower, 6-slag water unit, a-biomass, b-gasifying agent, c-boiler water, d-steam, e-pyrolysis gas, f-quenching water, g-ash water, h-synthesis gas. DETAILED DESCRIPTION

[0068] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0069] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0070] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0071] Example 1

[0072] A biomass gasification system, such as Figure 1 As shown, it includes a pressurized feeding unit 1, a fluidized bed gasification unit 2, a slag removal unit 3, an entrained bed high-temperature cracking unit 4, a synthesis gas washing unit 5, a slag-water unit 6 and a gasification agent conveying unit.

[0073] The fluidized bed gasification unit 2 includes a fluidized bed gasification furnace 21 and a high-temperature cyclone separator 22 , and the entrained flow high-temperature cracking unit 4 includes an entrained flow high-temperature cracking furnace 41 .

[0074] In this embodiment, the pressurized feeding unit 1 is connected to the fluidized bed gasifier 21, and can transport pressurized biomass a into the fluidized bed gasifier 21. The gasifying agent transporting unit is connected to the fluidized bed gasifier 21 and the entrained flow high-temperature cracking furnace 41, and can transport gasifying agent b into the fluidized bed gasifier 21 and the entrained flow high-temperature cracking furnace 41. The fluidized bed gasifier 21 is connected to the slag discharge unit 3 and is connected to the entrained flow high-temperature cracking furnace 41 through the high-temperature cyclone separator 22. The entrained flow high-temperature cracking furnace 41 is connected to the synthesis gas washing unit 5 and the slag water unit 6.

[0075] A biomass gasification method using the system of this embodiment includes the following steps:

[0076] (1) The biomass is pressurized by the pressurized feeding unit 1 and then transported to the fluidized bed gasification unit 2;

[0077] (2) In the fluidized bed gasifier 21, the biomass reacts with the gasifying agent to produce synthesis gas, which is then removed from the high-temperature cyclone separator 22 to form crude synthesis gas. The bottom slag is cooled and decompressed by the slag discharge unit 3 and then discharged.

[0078] (3) The crude synthesis gas is mixed with the gasifying agent in the entrained flow high-temperature cracking furnace 41, where tar and methane cracking reactions occur. The tar and methane in the crude synthesis gas are converted into effective gases CO and H2 at high temperatures.

[0079] (4) The high-temperature cracking gas after the cracking reaction is washed by the synthesis gas washing unit 5 to form the dust-removed synthesis gas h, and the black water produced by washing enters the slag water unit 6.

[0080] Example 2

[0081] A biomass gasification system includes a pressurized feeding unit 1 comprising a biomass bin 11, a biomass lock hopper 12, and a biomass sending hopper 13 connected in sequence; a slag discharge unit 3 comprising a slag discharge buffer tank 31, a slag lock hopper 32, and a slag bin 33 connected in sequence; an entrained flow high-temperature cracking furnace 41 comprising a burner 411, a radiation waste heat boiler 412, and a quenching module 413 arranged in sequence from top to bottom; and a synthesis gas washing unit 5 comprising a venturi scrubber 51, a cyclone separator 52, and a water washing tower 53 connected in sequence. The fluidized bed gasifier 21 is connected to the biomass delivery hopper 13 and the slag buffer tank 31 , the burner 411 is connected to the high-temperature cyclone separator 22 , the radiant waste heat boiler 412 is connected to the boiler water delivery unit and the steam output unit, the quenching module 413 is connected to the venturi scrubber 51 , the water scrubber 53 , and the slag-water unit 6 , the hydrocyclone 52 is connected to the slag-water unit 6 and the water scrubber 53 , and the water scrubber 53 is connected to the synthesis gas output unit and the slag-water unit 6 . The rest of the process is the same as in Example 1.

[0082] In this embodiment, the biomass gasification method specifically includes the following steps:

[0083] S1: The biomass is pressurized by the pressurized feeding unit 1 and then transported to the fluidized bed gasification unit 2;

[0084] S2: In the fluidized bed gasifier 21, the biomass reacts with the gasifying agent to produce synthesis gas, which is then removed from the high-temperature cyclone separator 22 to form crude synthesis gas. The bottom slag is cooled and decompressed by the slag discharge unit 3 before being discharged.

[0085] S3: The crude synthesis gas and the gasifying agent are uniformly mixed at the burner 411 in the entrained flow high-temperature cracking furnace 41, and the tar and methane cracking reaction occurs. The temperature is raised to 1000℃~1300℃, and the tar and methane in the crude synthesis gas are converted into effective gases CO and H2 at high temperature.

[0086] S4: The high-temperature cracked gas after the cracking reaction passes through the radiation waste heat boiler 412 to convert boiler water c into high-temperature and high-pressure steam d. After heat recovery, it enters the quenching module 413 to be cooled to 200°C to 250°C and washed to remove most of the ash;

[0087] S5: The quenched synthesis gas is washed by the venturi scrubber 51, the hydrocyclone 52 and the water scrubber 53 to form dust-free synthesis gas, which is then sent out of the system.

[0088] S6: The black water produced by the quenching module 413, the hydrocyclone separator 52 and the water scrubber 53 enters the slag water unit 6 for flash evaporation, cooling, sedimentation and clarification. The solid ash is dehydrated and discharged outside the boundary. The clarified ash water g is returned to the synthesis gas scrubbing unit 5 for recycling.

[0089] Example 3

[0090] A pressurized pure oxygen biomass gasification device coupled with a fluidized bed and an entrained flow system comprises a pressurized feeding system, a fluidized bed gasification system, a slag discharge system, an entrained bed pyrolysis system, a syngas scrubbing system, and a slag-water system. The biomass pressurized feeding system is used to feed and pressurize biomass. The fluidized bed gasification system gasifies biomass and produces syngas. The slag discharge system depressurizes and cools the slag produced by the fluidized bed gasifier before discharging it out of the system. The entrained bed pyrolysis system includes a radiant waste heat boiler system and a quenching system. The radiant waste heat boiler system recovers heat from the syngas. The quenching system cools the ash-containing syngas and discharges the fly ash in the syngas to a slag-water unit for treatment. The entrained bed pyrolysis system decomposes tar and methane in the syngas. The syngas scrubbing system includes a Venturi scrubber, a cyclone separator, and a water scrubber to purify and remove dust from the syngas. The slag-water system clarifies and separates solids from the slag-water. The solids are dehydrated and discharged from the system, and the clarified ash-water is returned to the scrubbing system for recycling.

[0091] The gasification system is equipped with a feed inlet and a slag discharge inlet. The feed inlet is connected to the pressurized feed system, and the slag discharge inlet is connected to the slag discharge system. The syngas outlet of the gasification system is connected to the pyrolysis system, which is connected to the syngas scrubbing system. The slag water outlet of the pyrolysis system is connected to the slag water unit. The ash water return port of the slag water system is connected to the syngas scrubbing system.

[0092] In this embodiment, the pressure of the gasification system and the high-temperature cracking system is 50 kPag to 8 MPa(g), the temperature of the gasification system is 700°C to 950°C, and the temperature of the high-temperature cracking system is 1000°C to 1300°C.

[0093] In this embodiment, the gasification system and the high-temperature cracking system are connected with a gasification agent.

[0094] In this embodiment, the gasifying agent is any one or more mixtures of pure oxygen / enriched oxygen / air and steam / CO2.

[0095] In this embodiment, the gasification furnace, high-temperature cyclone, and high-temperature cracking furnace are all provided with refractory linings.

[0096] In this embodiment, the slag buffer tank and the slag lock bucket are water-jacketed structures.

[0097] Example 4

[0098] A pressurized biomass gasification device coupling a fluidized bed and an entrained flow bed comprises a feeding system consisting of a biomass bin 11, a biomass lock hopper 12 and a biomass sending hopper 13; a gasification furnace system consisting of a fluidized bed gasifier 21 and a high-temperature cyclone separator 22; a slag discharge system consisting of a slag discharge buffer tank 31, a slag lock hopper 32 and a slag bin 33; a high-temperature cracking furnace system consisting of an entrained flow high-temperature cracking furnace 41; a synthesis gas washing system consisting of a venturi scrubber 51, a cyclone separator 52 and a water washing tower 53; and a slag-water system.

[0099] The fluidized bed gasifier 21 is provided with a feed / slag discharge port / synthesis gas outlet, which are respectively connected to the gasification agent conveying unit, the feed system, the slag discharge system and the high-temperature cyclone separator 22. The synthesis gas outlet of the high-temperature cyclone separator 22 is connected to the inlet of the fluidized bed high-temperature cracking furnace 41, and the solid phase outlet of the high-temperature cyclone separator 22 is connected to the inlet of the fluidized bed gasifier 21. The fluidized bed high-temperature cracking furnace 41 is connected to the Venturi scrubber 51, the cyclone separator 52 and the water washing tower 53 in sequence through pipelines.

[0100] The bottoms of the fluidized bed pyrolysis furnace 41, the cyclone separator 52, and the water scrubber 53 are connected to the slag water system through pipes. The outlet of the slag water system is connected to the bottom of the water scrubber 53. The middle and lower parts of the water scrubber 53 are connected to the middle and lower parts of the fluidized bed pyrolysis furnace 41 through pipes.

[0101] The gasifier system and the high-temperature cracking furnace system are connected to the gasifying agent.

[0102] The entrained-flow high-temperature cracking furnace 41 includes a burner 411 , a radiation waste heat boiler system (radiation waste heat boiler 412 ), and a quenching system (quenching module 413 ).

[0103] A pressurized biomass gasification method coupling a fluidized bed and an entrained flow bed comprises the following steps:

[0104] Step 1: The bed material and biomass are pressurized by the pressurized feeding system and then enter the gasifier;

[0105] Step 2: In the gasifier, the biomass reacts with the gasifying agent to generate syngas, which is then removed by a high-temperature cyclone to form crude syngas. The bottom slag is cooled and decompressed by a slag discharge system before being discharged.

[0106] Step 3: The crude synthesis gas and the gasifying agent are evenly mixed at the burner in the high-temperature cracking furnace, and the tar and methane cracking reaction occurs. The temperature is raised to 1000℃~1300℃, and the tar and methane in the crude synthesis gas are converted into effective gases CO and H2 at high temperature;

[0107] Step 4: The high-temperature cracking gas passes through the radiation waste heat boiler to convert boiler water into high-temperature and high-pressure steam. After recovering the heat, it enters the quenching system to be cooled to 200℃~250℃ and washed to remove most of the ash;

[0108] Step 5: The quenched syngas is washed by a venturi, a cyclone and a scrubber to form a dust-removed syngas, which is then sent out of the system;

[0109] Step 6: The black water produced by the pyrolysis furnace quenching system, hydrocyclone separator and water washing tower enters the slag water system for flash evaporation, cooling, sedimentation and clarification. The solid ash is discharged outside the boundary after dehydration, and the clarified ash water returns to the washing system for recycling.

[0110] Example 5

[0111] A pressurized biomass gasification device coupled with a fluidized bed and an entrained flow bed. Biomass a is formed into granules after screening, crushing, drying and granulation, and enters a biomass bin 11 for storage. After being pressurized by a biomass lock hopper 12, it enters a biomass sending hopper 13. The pressurized gas can be one or a mixture of N2, CO2 or synthesis gas. The biomass in the biomass sending hopper 13 enters the gasifier system (fluidized bed gasification unit 2) by pneumatic conveying.

[0112] Gasifying agent B is connected to the gasifier system, where the biomass and the gasifying agent undergo a gasification reaction to produce syngas. The gasification pressure is 50 kPag to 8 MPa(g) and the gasification temperature is 700°C to 950°C. The ash-containing syngas at the outlet of the gasifier (fluidized bed gasifier 21) is dedused by a high-temperature cyclone separator 22 before entering a high-temperature cracking furnace (entrained-bed high-temperature cracking furnace 41). Fly ash captured by the high-temperature cyclone separator 22 is returned to the gasifier via the feed leg for further gasification.

[0113] The slag discharge port at the bottom of the gasifier is connected to the slag discharge buffer tank 31. After the high-temperature slag is discharged into the slag buffer tank 31 to cool down, it is depressurized and further cooled in the slag lock hopper 32 before being discharged into the slag bin 33.

[0114] The pyrolysis furnace system (entrained-flow pyrolysis unit 4) comprises a burner 411, a furnace, a radiant waste heat boiler 412, and a quenching system (quenching module 413). Gasifying agent b is connected to burner 411 via a pipeline. Inside burner 411, it mixes with the raw syngas, which has been dust-removed by the high-temperature cyclone separator 22, and undergoes a pyrolysis reaction, converting tar and methane into the effective gases CO and H₂. The pyrolysis furnace pressure ranges from 50 kPa to 8 MPa(g), and the pyrolysis temperature ranges from 1000°C to 1300°C. The pyrolysis gas passes through the radiant waste heat boiler 412 for cooling, generating high-temperature, high-pressure steam to recover the syngas heat. The cooled pyrolysis gas passes through the quenching system to cool to 200°C to 250°C, where it is scrubbed to remove most of the ash. The scrubbed pyrolysis gas e enters the Venturi scrubber 51, and the ash is discharged through the slag pool into the slag water system (slag water unit 6).

[0115] The fly ash and water in the syngas are fully mixed in the Venturi scrubber 51 and then enter the hydrocyclone 52 to further separate the syngas and the solid-containing black water. After separation, the syngas enters the water scrubber 53 for further washing, so that the ash content in the syngas h is less than 1mg / Nm 3 The solid-containing black water produced in the hydrocyclone 52 and a portion of the bottom of the water scrubber 53 is discharged into the slag water system for flash evaporation, cooling, sedimentation, and clarification. The solid ash is dehydrated and discharged, and the clarified ash water g is returned to the scrubbing system for recycling. Another portion of the black water from the bottom of the water scrubber 53 is used as quench water f for the high-temperature cracking furnace and enters the quenching system to cool the cracked gas.

[0116] In this example, corn straw pellets were used as biomass. The gasifying agent was 99.6% oxygen, the transport gas was CO2, and the fluidized bed gasifier was operated at a pressure of 4.0 MPa and a temperature of 800°C. The entrained flow pyrolysis furnace was operated at a pressure of 4.0 MPa and a temperature of 1200°C. The carbon conversion rate was >98%, and the resulting syngas had the following gas compositions: H2 30-35%, CO 35-40%, CO2 25-30%, CH4 <0.4%, and no tar.

[0117] The above description of the embodiments is intended to facilitate understanding and use of the utility model by those skilled in the art. Those skilled in the art will readily be able to make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the utility model is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of this utility model without departing from the scope of this utility model should be within the scope of protection of this utility model.

Claims

1. A biomass gasification system, characterized in that: It comprises a pressurized feeding unit (1), a fluidized bed gasification unit (2), a slag removal unit (3), an entrained bed high-temperature cracking unit (4), a synthesis gas washing unit (5), a slag-water unit (6) and a gasification agent conveying unit; The fluidized bed gasification unit (2) comprises a fluidized bed gasification furnace (21) and a high-temperature cyclone separator (22), and the fluidized bed gasification furnace (21) is connected to the pressurized feeding unit (1), the gasifying agent conveying unit, the high-temperature cyclone separator (22) and the slag discharge unit (3); The entrained flow high temperature cracking unit (4) comprises an entrained flow high temperature cracking furnace (41), and the entrained flow high temperature cracking furnace (41) is connected to a high temperature cyclone separator (22), a gasifying agent conveying unit, a synthesis gas washing unit (5), and a slag water unit (6).

2. The biomass gasification system according to claim 1, characterized in that: The pressurized feeding unit (1) comprises a biomass bin (11), a biomass locking hopper (12) and a biomass sending hopper (13) which are connected in sequence; The biomass locking hopper (12) is connected to the pressurized gas delivery unit, and the biomass sending hopper (13) is connected to the fluidized bed gasification unit (2).

3. The biomass gasification system according to claim 1, characterized in that: The fluidized bed gasifier (21) is provided with a biomass feed port, a gasifying agent feed port, a synthesis gas outlet, a fly ash return port, and a slag discharge port; The biomass feed port is connected to the pressurized feed unit (1), the gasifying agent feed port is connected to the gasifying agent conveying unit, the synthesis gas outlet and the fly ash return port are both connected to the high-temperature cyclone separator (22), and the slag discharge port is connected to the slag discharge unit (3).

4. The biomass gasification system according to claim 1, characterized in that: The slag discharge unit (3) comprises a slag discharge buffer tank (31), a slag lock bucket (32) and a slag bin (33) which are connected in sequence; The slag discharge buffer tank (31) is connected to the bottom of the fluidized bed gasification furnace (21).

5. The biomass gasification system according to claim 1, characterized in that: The entrained flow high-temperature cracking furnace (41) comprises a burner (411), a radiation waste heat boiler (412), and a quenching module (413) arranged in sequence from top to bottom; The burner (411) is connected to the high-temperature cyclone separator (22) and the gasification agent delivery unit, the radiation waste heat boiler (412) is connected to the boiler water delivery unit and the steam output unit, and the quenching module (413) is connected to the synthesis gas washing unit (5) and the slag water unit (6).

6. The biomass gasification system according to claim 5, characterized in that: The synthesis gas washing unit (5) includes a venturi scrubber (51), a hydrocyclone (52) and a water scrubber (53) connected in sequence; The venturi scrubber (51) is connected to the quenching module (413), the hydrocyclone (52) is connected to the slag-water unit (6), and the water scrubber (53) is connected to the quenching module (413), the slag-water unit (6), and the synthesis gas output unit.

7. The biomass gasification system according to claim 6, characterized in that: The water washing tower (53) is provided with a synthesis gas inlet, a quenching water return port, a slag water outlet and an ash water inlet; The synthesis gas inlet is connected to the hydrocyclone separator (52), the quenching water return port is connected to the fluidized flow high temperature cracking furnace (41), and the slag water outlet and the ash water inlet are both connected to the slag water unit (6).

8. The biomass gasification system according to claim 1, characterized in that: The slag water unit (6) is provided with a black water inlet, a washing water inlet and a gray water outlet; The black water inlet is connected to the fluidized-flow high-temperature cracking furnace (41), and the wash water inlet and the gray water outlet are both connected to the synthesis gas washing unit (5).

9. The biomass gasification system according to claim 1, characterized in that: The gasification agent delivery unit includes a storage tank storing pure oxygen / oxygen-enriched air and steam / CO2 and a delivery pipeline.

10. The biomass gasification system according to claim 1, characterized in that: The fluidized bed gasification furnace (21), the high-temperature cyclone separator (22), and the fluidized bed high-temperature cracking furnace (41) are all provided with refractory linings.

Images