Biomass gasification system and gasification method

Abstract

The invention relates to a biomass gasification system and a gasification method. The gasification system 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 gasification 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 invention couples the advantages of the fluidized bed and the 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] This invention relates to the field of biomass gasification to syngas technology, and in particular to a biomass gasification system and gasification method. Background Technology

[0002] Biomass, as a renewable resource, is characterized by abundant resources, wide geographical distribution, and stable energy reserves. The production of syngas from biomass gasification for the production of sustainable aviation fuel, green methanol, and other high-end green chemicals plays a vital role in achieving a low-carbon economy and building a green renewable energy system.

[0003] Biomass gasification technology is mainly divided into fixed-bed gasification, fluidized-bed gasification, and entrained gasification. Patent CN202898353U discloses a multi-stage fixed-bed biomass gasifier, which includes a longitudinally arranged furnace body. The furnace body includes a conical tailings section at the bottom and at least two gas-producing sections above the tailings section. Patent CN101560411A discloses an upward-suction household biomass gasification device, which is a vertical cylindrical structure. Its structure consists of an upper section of dry distillation chamber, a middle section of main gasification chamber, and a lower section of ash chamber. Each section is separated by a regenerator grid and a regenerator grate. The main gasification chamber is surrounded by a radiating cylinder. Patent CN108559548A discloses a biomass fluidized-bed gasifier, including a furnace body and pipes. The upper and top parts of the outer wall of the furnace body are covered with an insulation layer. A water jacket is located from the upper part of the outer wall to the bottom, and a steam outlet is provided at the top of the water jacket. During the gasification process, the energy generated by the reaction is exchanged with the cooling water in the water jacket, recovering some of the energy. Patent CN113105917A discloses a biomass fluidized bed multi-stage gasifier device. The internal structure of the gasifier is divided into a lower high-temperature combustion chamber, a middle high-temperature pyrolysis chamber, and an upper steam gasification chamber, which uses biomass as raw material to produce high-calorific-value gasified gas and high-quality biochar / activated carbon.

[0004] The aforementioned patented gas components contain a large amount of tar and methane, which can easily clog downstream equipment and reduce the content of effective gases CO and H2, making them unsuitable for the synthesis of downstream chemical products.

[0005] Biomass itself has low energy density, high volatile matter content, high oxygen content, high alkali metal content, and high chloride ion content. Its ash component is mainly SiO2, and its properties differ greatly from those of coal, specifically in the following ways:

[0006] (1) Fixed-bed gasification technology has high requirements for the strength and thermal stability of raw materials. The biomass gasification process is unstable, oxygen flow in the furnace is biased, the gasifier outlet temperature is too high, and the wastewater contains substances such as tar and phenol, which are difficult to treat. The gas at the gasifier outlet contains a large amount of tar and methane. The tar will block the pipeline when it condenses downstream, and the presence of methane will reduce the effective gas CO and H2, which is not conducive to downstream chemical synthesis.

[0007] (2) Fluidized bed gasification has relatively broad requirements for raw materials, without requirements for strength, thermal stability, pulverization, and viscosity-temperature characteristics. However, currently operating fluidized bed biomass gasification units mainly use atmospheric air gasification, primarily for boiler combustion power generation, which is not suitable for the needs of chemical synthesis. Moreover, simple fluidized bed gasification also has problems such as high tar and methane content and low carbon conversion rate.

[0008] (3) The gasification temperature of the fluidized bed is relatively high, the syngas contains no tar and has a very low methane content, but it requires the raw material particle size to be in the micrometer range, the pretreatment is complicated, the energy consumption is extremely high, and it is difficult to ensure the stable delivery of the raw material line. The ash slag has a high silicon-aluminum ratio, making it difficult to achieve "slag-to-slag" and unable to guarantee the long-term operation of the gasifier.

[0009] Therefore, there is an urgent need to develop an economical and reliable biomass gasification technology for the synthesis of sustainable aviation fuels and green methanol and other chemical products. Summary of the Invention

[0010] The purpose of this invention is to provide a biomass gasification system and gasification method that combines the advantages of fluidized bed and entrained bed.

[0011] The objective of this invention can be achieved through the following technical solution: a biomass gasification system, comprising a pressurized feeding unit, a fluidized bed gasification unit, a slag discharge unit, a high-temperature pyrolysis unit, a syngas washing unit, a slag-water unit, and a gasifying agent conveying unit;

[0012] The fluidized bed gasification unit includes a fluidized bed gasifier and a high-temperature cyclone separator. The fluidized bed gasifier is connected to a pressurized feeding unit, a gasifying agent conveying unit, a high-temperature cyclone separator, and a slag discharge unit.

[0013] The fluidized bed high-temperature pyrolysis unit includes a fluidized bed high-temperature pyrolysis furnace, which is connected to a high-temperature cyclone separator, a gasifying agent conveying unit, a syngas washing unit, and a slag-water unit.

[0014] This invention combines the advantages of fluidized bed and entrained flow bed – wide adaptability to raw materials, simple feeding, and no tar; while overcoming the shortcomings of both – tar exists in fluidized bed gasification and pulverization is difficult in entrained flow bed; it features wide applicability to raw materials, high effective gas content, no tar, and low energy consumption.

[0015] Preferably, the pressurized feeding unit includes a biomass bin, a biomass lock hopper, and a biomass dispensing hopper connected in sequence;

[0016] The biomass lock hopper is connected to the pressurized gas delivery unit, and the biomass delivery hopper is connected to the fluidized bed gasification unit.

[0017] Preferably, the fluidized bed gasifier is provided with a biomass inlet, a gasifying agent inlet, a syngas outlet, a fly ash return outlet, and a slag discharge outlet;

[0018] The biomass inlet is connected to the pressurized feeding unit, the gasifying agent inlet is connected to the gasifying agent conveying unit, the syngas outlet and fly ash return outlet are both connected to the high-temperature cyclone separator, and the slag discharge outlet is connected to the slag discharge unit.

[0019] Preferably, the slag discharge unit includes a slag discharge buffer tank, a slag lock hopper, and a slag bin connected in sequence;

[0020] The slag discharge buffer tank is connected to the bottom of the fluidized bed gasifier.

[0021] Preferably, the fluidized bed high-temperature pyrolysis furnace includes, from top to bottom, a burner, a radiant waste heat boiler, and a quench module;

[0022] The burner is connected to the high-temperature cyclone separator and the gasifying agent conveying unit, the radiant waste heat boiler is connected to the boiler water conveying unit and the steam output unit, and the quench module is connected to the syngas scrubbing unit and the slag water unit.

[0023] More preferably, the burner includes a premixing chamber, a syngas passage, an oxygen passage, a purge gas passage, and internal / intermediate / external cooling water passages.

[0024] More preferably, the syngas channel is connected to the high-temperature cyclone separator, the oxygen channel is connected to the gasifying agent delivery unit, the purge gas channel is connected to the protective gas source, the syngas channel, the oxygen channel, and the purge gas channel are all connected to the premixing chamber, and the inner / middle / outer cooling water channels are connected to the burner cooling water pipeline.

[0025] More preferably, the radiant waste heat boiler includes water pipes and a membrane wall.

[0026] More preferably, the water pipe is connected to the boiler water delivery unit and the steam output unit, and the membrane wall is installed in the lower part of the fluidized bed high-temperature pyrolysis furnace and is connected to the boiler water pipe.

[0027] More preferably, the quenching module includes a quenching ring, a downcomer, an upcomer, and a slag pool.

[0028] More preferably, the downcomer and the riser are arranged coaxially from the inside to the outside, the quench ring is located above the downcomer and the riser, and the slag pool is located below the downcomer and the riser and is connected to the slag-water unit.

[0029] In this invention, the working principle of the fluidized bed high-temperature pyrolysis furnace is as follows: The crude syngas, after dust removal by a high-temperature cyclone separator, enters the premixing chamber purged with protective gas through the syngas channel. It mixes with the gasifying agent introduced through the oxygen channel and undergoes a pyrolysis reaction. During the reaction, cooling water is introduced into the burners through the inner / middle / outer cooling water channels to cool and protect the burners. The high-temperature pyrolysis gas after the pyrolysis reaction enters the radiant waste heat boiler along the furnace. After being cooled by the membrane wall heat exchange, the boiler water is simultaneously heated, converting it into high-temperature, high-pressure steam. After recovering heat through the radiant waste heat boiler, the pyrolysis gas enters the quench module along the furnace. After cooling and preliminary dust removal in the quench module, the pyrolysis gas enters the syngas washing unit. The quench water enters the downcomer through the quench ring to directly contact and cool the pyrolysis gas before passing through the slag pool and entering the slag-water unit.

[0030] More preferably, the syngas scrubbing unit includes a Venturi scrubber, a hydrocyclone separator, and a water scrubbing tower connected in sequence;

[0031] The Venturi scrubber is connected to the quench module, the hydrocyclone separator is connected to the slag-water unit, and the water washing tower is connected to the quench module, the slag-water unit, and the syngas output unit.

[0032] More preferably, the water washing tower is provided with a syngas inlet, a quench water return outlet, a slag water outlet, and an ash water inlet;

[0033] The syngas inlet is connected to the cyclone separator, the quench water return port is connected to the high-temperature pyrolysis furnace, and the slag water outlet and ash water inlet are both connected to the slag water unit.

[0034] Preferably, the slag and water unit is provided with a black water inlet, a washing water inlet, and a grey water outlet;

[0035] The black water inlet is connected to the high-temperature pyrolysis furnace of the fluidized bed, and the washing water inlet and the ash water outlet are both connected to the syngas washing unit.

[0036] More preferably, the slag-water unit includes a flash tank, a settling tank, an ash water tank, a stripping tower, and a filter dewatering device.

[0037] More preferably, the flash tank is provided with a black water inlet and a washing water inlet, and is connected to a settling tank, which is connected to an ash water tank, which is connected to a stripping tower, and the stripping tower is provided with an ash water outlet.

[0038] In this invention, the working principle of the slag and water unit is as follows: the black water and washing water generated by the fluidized bed high-temperature pyrolysis furnace and the syngas washing unit enter the flash tank for flash cooling. After flash cooling, the black water enters the settling tank for settling and clarification, and then enters the ash water tank. The ash water in the ash water tank is stripped and returned to the syngas washing unit for recycling. The filter slurry at the bottom of the settling tank is dewatered by the dewatering device to form a filter cake and sent out of the boundary area.

[0039] Preferably, the vaporizing agent delivery unit includes a storage tank containing pure oxygen / oxygen-enriched / air and vapor / CO2 and a delivery pipeline.

[0040] Preferably, the fluidized bed gasifier, the high-temperature cyclone separator, and the high-temperature pyrolysis furnace are all equipped with refractory linings.

[0041] Preferably, the slag buffer tank and slag lock hopper are water jacket structures.

[0042] Preferably, the fluidized bed gasification unit has a pressure of 50 kPag to 8 MPa (g) and a temperature of 700℃ to 950℃.

[0043] Preferably, the pressure of the high-temperature pyrolysis unit in the fluidized bed is 50 kPag to 8 MPa (g), and the temperature is 1000℃ to 1300℃.

[0044] A biomass gasification method, using the above system, includes the following steps:

[0045] (1) Biomass is pressurized by the pressurized feeding unit and then transported to the fluidized bed gasification unit;

[0046] (2) Biomass reacts with gasifying agent in fluidized bed gasifier to produce syngas. After dust removal by high temperature cyclone separator, crude syngas is formed. Bottom ash is discharged after cooling and depressurization by ash discharge unit.

[0047] (3) After the crude syngas and the gasifying agent are mixed in the high-temperature pyrolysis furnace of the fluidized bed, tar and methane pyrolysis reaction occurs. The tar and methane in the crude syngas are converted into effective gases CO and H2 at high temperature.

[0048] (4) The high-temperature pyrolysis gas after the pyrolysis reaction is washed by the syngas washing unit to form dust removal syngas, and the black water generated by the washing enters the slag water unit.

[0049] Preferably, the biomass gasification method specifically includes the following steps:

[0050] S1: Biomass is pressurized by the pressurized feeding unit and then transported to the fluidized bed gasification unit;

[0051] S2: Biomass reacts with gasifying agent in fluidized bed gasifier to produce syngas. After dust removal by high-temperature cyclone separator, crude syngas is formed. Bottom ash is discharged after cooling and depressurization by ash discharge unit.

[0052] S3: After the crude syngas and gasifying agent are uniformly mixed at the burner in the fluidized bed high-temperature pyrolysis furnace, tar and methane pyrolysis reactions occur, and the temperature is raised to 1000℃~1300℃. The tar and methane in the crude syngas are converted into effective gases CO and H2 at high temperature.

[0053] S4: The high-temperature pyrolysis gas after the pyrolysis reaction passes through the radiant waste heat boiler to convert the boiler water into high-temperature and high-pressure steam. After recovering the heat, it enters the quench module to be cooled to 200℃~250℃ and is washed to remove most of the ash and slag.

[0054] S5: The quenched syngas is washed by a Venturi scrubber, a hydrocyclone separator and a water scrubbing tower to form dust-removed syngas, which is then sent out of the system.

[0055] S6: The black water generated by the quench module, hydrocyclone separator and water washing tower enters the slag water unit for flash evaporation, cooling, settling and clarification. The solid ash slag is discharged outside the boundary after dewatering, and the clarified ash water is returned to the syngas washing unit for recycling.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. This invention provides a stable and cost-effective system for producing high-quality syngas from biomass.

[0058] 2. This invention provides a pressurized biomass gasification system that couples fluidized bed and entrained flow bed, combining the advantages of both while overcoming their respective shortcomings. It features wide applicability of raw materials, high effective gas content, no tar, and low energy consumption.

[0059] 3. The raw materials of this invention are widely adaptable. Straw, fruit shells, rice husks, furfural residue, agricultural product processing residues, timber, organic solid waste, and domestic waste 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 biomass.

[0060] 4. The present invention has a high carbon conversion rate. The carbon-containing fly ash generated by the gasification system is further gasified in the high-temperature pyrolysis furnace, resulting in a carbon conversion rate of >98%.

[0061] 5. This invention produces high-quality syngas. A high-temperature pyrolysis furnace further converts the syngas produced in the gasification furnace, cracking the tar and methane in the syngas at high temperatures. Burners ensure uniform mixing of the syngas and oxygen produced in the gasification furnace, avoiding localized high temperatures and short-circuiting problems of tar and methane caused by point-to-point oxygen supply, resulting in complete tar conversion and a methane conversion rate >98%. Existing syngas tar and methane purification methods generally employ water washing or catalytic methods. Water washing generates large amounts of tar-containing wastewater, and catalytic methods can lead to catalyst blockage and poisoning. The dust content of the syngas outside the boundary area in this invention is <1 mg / Nm³. 3 This solved the blockage problem in downstream devices.

[0062] 6. This invention boasts high energy recovery rate and operational reliability. Utilizing a radiant waste heat boiler and a quench coupling system, a large amount of high-temperature, high-pressure steam is generated simultaneously with syngas cooling, improving energy recovery rate. It eliminates the need for a complex syngas cooler and an expensive dust collector system, while simultaneously solidifying alkali metals to prevent contamination of the syngas cooler by alkali metals and fly ash, thus avoiding shutdowns caused by ash accumulation, wear, and corrosion in the syngas cooler and dust collector. The large water circulation volume in the quench process washing tower ensures a chloride ion concentration of <25ppm in the washing system, preventing corrosion problems caused by excessively high chloride ion concentrations in pipelines and equipment.

[0063] 7. This invention has low overall energy consumption. It adopts pressurized pure oxygenation, resulting in a low content of impurity gases in the syngas, high syngas pressure, low load on the purification system, and low power consumption in the synthesis compression process.

[0064] 8. This invention is environmentally friendly. The syngas contains no tar components, the slag is discharged dry, and the wastewater contains no tar, phenols, or other difficult-to-treat substances.

[0065] 9. This invention can reduce alkali metal radiation, reduce the risk of corrosion, scaling and blockage, and is conducive to the long-term stable operation of the system.

[0066] 10. This invention has low unit effective gas biomass and oxygen consumption, low investment, economical syngas cost, and high product quality. It can be used to produce sustainable aviation fuel, green methanol, and other high-end green chemical products. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the biomass gasification system of the present invention;

[0068] In the diagram: 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-Gas flow bed high-temperature pyrolysis unit, 41-Gas flow bed high-temperature pyrolysis furnace, 411-Burn, 412-Radiant waste heat boiler, 413-Quenching module, 5-Syngas scrubbing unit, 51-Venturi scrubber, 52-Swirl separator, 53-Water scrubbing 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-Syngas. Detailed Implementation

[0069] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0070] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0071] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0072] Example 1

[0073] 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 discharge unit 3, a high-temperature pyrolysis unit 4, a syngas washing unit 5, a slag-water unit 6, and a gasifying agent conveying unit.

[0074] The fluidized bed gasification unit 2 includes a fluidized bed gasifier 21 and a high-temperature cyclone separator 22, and the entrained bed high-temperature pyrolysis unit 4 includes an entrained bed high-temperature pyrolysis furnace 41.

[0075] In this embodiment, the pressurized feeding unit 1 is connected to the fluidized bed gasifier 21 and can feed pressurized biomass a into the fluidized bed gasifier 21. The gasifying agent conveying unit is connected to the fluidized bed gasifier 21 and the entrained flow bed high-temperature pyrolysis furnace 41 and can feed gasifying agent b into the fluidized bed gasifier 21 and the entrained flow bed high-temperature pyrolysis furnace 41. The fluidized bed gasifier 21 is connected to the slag discharge unit 3 and is connected to the entrained flow bed high-temperature pyrolysis furnace 41 through the high-temperature cyclone separator 22. The entrained flow bed high-temperature pyrolysis furnace 41 is connected to the syngas washing unit 5 and the slag and water unit 6.

[0076] A biomass gasification method using the system of this embodiment includes the following steps:

[0077] (1) Biomass is pressurized by pressurized feeding unit 1 and then transported to fluidized bed gasification unit 2;

[0078] (2) Biomass reacts with gasifying agent in fluidized bed gasifier 21 to produce syngas. After dust removal by high temperature cyclone separator 22, crude syngas is formed. Bottom ash is discharged after cooling and depressurization by ash discharge unit 3.

[0079] (3) After the crude syngas and the gasifying agent are mixed in the high-temperature pyrolysis furnace 41 of the fluidized bed, tar and methane pyrolysis reaction occurs. The tar and methane in the crude syngas are converted into effective gases CO and H2 at high temperature.

[0080] (4) The high-temperature pyrolysis gas after the pyrolysis reaction is washed by the syngas washing unit 5 to form dust removal syngas h, and the black water generated by the washing enters the slag water unit 6.

[0081] Example 2

[0082] A biomass gasification system includes a pressurized feeding unit 1 comprising a biomass bin 11, a biomass lock hopper 12, and a biomass delivery 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; a fluidized bed high-temperature pyrolysis furnace 41 comprising a burner 411, a radiant waste heat boiler 412, and a quench module 413 arranged in sequence from top to bottom; and a syngas scrubbing unit 5 comprising a Venturi scrubber 51, a hydrocyclone separator 52, and a water scrubbing tower 53 connected in sequence. The fluidized bed gasifier 21 is connected to the biomass feeding hopper 13 and the slag discharge 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 conveying unit and the steam output unit; the quench module 413 is connected to the Venturi scrubber 51, the water washing tower 53, and the slag-water unit 6; the hydrocyclone separator 52 is connected to the slag-water unit 6 and the water washing tower 53; and the water washing tower 53 is connected to the syngas output unit and the slag-water unit 6. The rest is the same as in Example 1.

[0083] In this embodiment, the biomass gasification method specifically includes the following steps:

[0084] S1: Biomass is pressurized by pressurized feeding unit 1 and then transported to fluidized bed gasification unit 2;

[0085] S2: Biomass reacts with gasifying agent in fluidized bed gasifier 21 to produce syngas. After dust removal by high temperature cyclone separator 22, crude syngas is formed. Bottom ash is discharged after cooling and depressurization by ash discharge unit 3.

[0086] S3: After the crude syngas and gasifying agent are uniformly mixed at the burner 411 in the fluidized bed high-temperature pyrolysis furnace 41, tar and methane pyrolysis reactions occur, and the temperature is raised to 1000℃~1300℃. The tar and methane in the crude syngas are converted into effective gases CO and H2 at high temperature.

[0087] S4: The high-temperature pyrolysis gas after the pyrolysis reaction is converted into high-temperature and high-pressure steam d by the radiant waste heat boiler 412. After recovering the heat, it enters the quench module 413 and is cooled to 200℃~250℃, and most of the ash and slag are washed away.

[0088] S5: The quenched syngas is washed by Venturi scrubber 51, hydrocyclone separator 52 and water scrubbing tower 53 to form dust-removed syngas, which is then sent out of the system.

[0089] S6: The black water generated by the quench module 413, hydrocyclone separator 52 and water washing tower 53 enters the slag water unit 6 for flash evaporation, cooling, sedimentation and clarification. The solid ash slag is discharged outside the boundary after dehydration, and the clarified ash water g is returned to the syngas washing unit 5 for recycling.

[0090] Example 3

[0091] A pressurized pure oxygen biomass gasification device coupling fluidized bed and entrained gas flow (AGC) systems includes a pressurized feeding system, a fluidized bed gasification system, a slag discharge system, an AGC high-temperature pyrolysis system, a syngas scrubbing system, and a slag-water system. The pressurized feeding system is used for feeding and pressurizing biomass. The fluidized bed gasification system is used to gasify the biomass and produce syngas. The slag discharge system depressurizes and cools the slag produced by the fluidized bed gasifier before discharging it from the system. The AGC high-temperature pyrolysis system includes a radiant waste heat boiler system and a quench system. The radiant waste heat boiler system is used to recover heat from the syngas. The quench system is used to cool the ash-containing syngas and discharge the fly ash from the syngas to the slag-water unit for treatment. The AGC high-temperature pyrolysis system is used to decompose tar and methane in the syngas. The syngas scrubbing system includes a Venturi scrubber, a cyclone separator, and a water scrubbing tower for purifying and removing dust from the syngas. The slag-water system is used to clarify and separate solids from the slag-water. The solids are discharged from the system after dehydration, and the clarified ash water is returned to the scrubbing system for recycling.

[0092] The gasification system has a feed inlet and a slag discharge outlet. The feed inlet is connected to a pressurized feed system, and the slag discharge outlet is connected to a slag discharge system. The syngas outlet of the gasification system is connected to a high-temperature pyrolysis system, the syngas outlet of the high-temperature pyrolysis system is connected to a syngas scrubbing system, and the slag-water outlet of the high-temperature pyrolysis system is connected to a slag-water unit. The ash water return outlet of the slag-water system is connected to the syngas scrubbing system.

[0093] In this embodiment, the pressure of the gasification system and the high-temperature pyrolysis system is 50 kPag to 8 MPa (g), the temperature of the gasification system is 700℃ to 950℃, and the temperature of the high-temperature pyrolysis system is 1000℃ to 1300℃.

[0094] In this embodiment, the gasification system and the high-temperature pyrolysis system are connected to a gasifying agent.

[0095] In this embodiment, the vaporizing agent is any one or more mixtures of pure oxygen, oxygen-enriched oxygen, air and steam, and CO2.

[0096] In this embodiment, the gasifier, high-temperature cyclone furnace, and high-temperature pyrolysis furnace are all equipped with refractory linings.

[0097] In this embodiment, the slag buffer tank and slag lock hopper are water jacket structures.

[0098] Example 4

[0099] A pressurized biomass gasification device coupling a fluidized bed and a gas flow bed includes a feeding system consisting of a biomass silo 11, a biomass lock hopper 12, and a biomass feeding 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 silo 33; a high-temperature pyrolysis furnace system consisting of a gas flow bed high-temperature pyrolysis furnace 41; a syngas scrubbing system consisting of a Venturi scrubber 51, a hydrocyclone separator 52, and a water scrubbing tower 53; and a slag-water system.

[0100] The fluidized bed gasifier 21 is equipped with a feed / slag discharge port / syngas outlet, which are respectively connected to the gasification agent conveying unit, the feeding system, the slag discharge system and the high-temperature cyclone separator 22. The syngas outlet of the high-temperature cyclone separator 22 is connected to the inlet of the fluidized bed high-temperature pyrolysis 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 pyrolysis furnace 41 is connected to the Venturi scrubber 51, the hydrocyclone separator 52 and the water washing tower 53 in sequence through pipelines.

[0101] The bottom of the fluidized bed high-temperature pyrolysis furnace 41, the hydrocyclone separator 52, and the water washing tower 53 are connected to the slag and water system through pipelines. The outlet of the slag and water system is connected to the bottom of the water washing tower 53. The middle and lower part of the water washing tower 53 are connected to the middle and lower part of the fluidized bed high-temperature pyrolysis furnace 41 through pipelines.

[0102] The gasification furnace system and the high-temperature pyrolysis furnace system are connected to the gasification agent.

[0103] The fluidized bed high-temperature pyrolysis furnace 41 includes a burner 411, a radiant waste heat boiler system (radiant waste heat boiler 412), and a quench system (quench module 413).

[0104] A pressurized biomass gasification method coupling a fluidized bed and an entrained flow bed includes the following steps:

[0105] Step 1: The bed material and biomass are pressurized by the pressurized feeding system and then enter the gasifier;

[0106] Step 2: Biomass reacts with gasifying agent in the gasifier to produce syngas. After passing through a high-temperature cyclone dust collector, crude syngas is formed. The bottom ash is discharged after being cooled and depressurized by the ash discharge system.

[0107] Step 3: After the crude syngas and gasifying agent are uniformly mixed at the burner in the high-temperature pyrolysis furnace, tar and methane pyrolysis reactions occur, and the temperature is raised to 1000℃~1300℃. The tar and methane in the crude syngas are converted into effective gases CO and H2 at high temperature.

[0108] Step 4: The high-temperature pyrolysis gas passes through the radiant waste heat boiler, where it converts the boiler water into high-temperature and high-pressure steam. After recovering the heat, it enters the quench system and is cooled to 200℃~250℃. Most of the ash and slag are also washed away.

[0109] Step 5: The quenched synthesis gas is washed by a venturi, cyclone and scrubbing tower to form dust-removed synthesis gas, which is then sent out of the system;

[0110] Step Six: The black water generated by the high-temperature pyrolysis furnace quench system, hydrocyclone separator and water washing tower enters the slag water system for flash evaporation, cooling, settling and clarification. The solid ash slag is discharged outside the boundary after dewatering, and the clarified ash water is returned to the washing system for recycling.

[0111] Example 5

[0112] A pressurized biomass gasification device coupling fluidized bed and entrained flow bed is disclosed. Biomass a is sieved, crushed, dried and granulated to form granules, which are then stored in biomass bin 11. After being pressurized by biomass lock hopper 12, it enters biomass sending hopper 13. The pressurizing gas can be one or a mixture of N2, CO2 or syngas. The biomass in biomass sending hopper 13 enters the gasification furnace system (fluidized bed gasification unit 2) by pneumatic conveying.

[0113] Gasifying agent b is connected to the gasifier system. Within the gasifier system, biomass reacts with the gasifying agent to produce syngas. The gasification pressure is 50 kPag to 8 MPa (g), and the gasification temperature is 700℃ to 950℃. The ash-containing syngas from the gasifier (fluidized bed gasifier 21) outlet passes through a high-temperature cyclone separator 22 for dust removal and then enters a high-temperature pyrolysis furnace (flow bed high-temperature pyrolysis furnace 41). The fly ash collected by the high-temperature cyclone separator 22 is returned to the gasifier via the feed leg for further gasification.

[0114] The bottom slag discharge port 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 passes through the slag lock hopper 32 for depressurization and further cooling, and then is discharged into the slag bin 33.

[0115] The high-temperature pyrolysis furnace system (fluidized bed high-temperature pyrolysis unit 4) includes burners 411, a furnace chamber, a radiant waste heat boiler 412, and a quench system (quench module 413). Gasifying agent b is connected to burner 411 via a pipeline. Inside burner 411, it mixes with the crude syngas after dust removal by the high-temperature cyclone separator 22, undergoing a high-temperature pyrolysis reaction. This converts tar and methane into effective gases CO and H2. The pyrolysis furnace pressure is 50 kPag–8 MPa(g), and the pyrolysis temperature is 1000℃–1300℃. The high-temperature pyrolysis gas is cooled by the radiant waste heat boiler 412, generating high-temperature, high-pressure steam to recover the heat from the syngas. The cooled pyrolysis gas is then cooled to 200℃–250℃ by the quench system, and most of the ash is removed. The washed pyrolysis gas e enters the Venturi scrubber 51, and the ash is discharged into the slag water system (slag water unit 6) through the slag pool.

[0116] After the fly ash and water in the syngas are thoroughly mixed in the Venturi scrubber 51, they enter the hydrocyclone separator 52 for further separation of the syngas and solid-containing black water. The separated syngas then enters the water washing tower 53 for further washing, ensuring that the ash content in the syngas h is <1 mg / Nm³. 3 The black water containing solids generated from the hydrocyclone separator 52 and a portion of the bottom water from the washing tower 53 is discharged into the slag-water system for flash evaporation, cooling, settling, and clarification. The solid ash residue is discharged outside the boundary after dewatering, and the clarified ash water g is returned to the washing system for recycling. Another portion of the black water from the bottom water from the washing tower 53 is used as quench water f in the high-temperature pyrolysis furnace to enter the quench system to cool the pyrolysis gas.

[0117] In this embodiment, the biomass used is corn granular straw. The gasifying agent is 99.6% oxygen by volume, and the transport gas is CO2. The fluidized bed gasifier operates at a pressure of 4.0 MPa and a temperature of 800°C, while the entrained flow bed high-temperature pyrolysis furnace operates at a pressure of 4.0 MPa and a temperature of 1200°C. The carbon conversion rate is >98%, and the composition of the produced syngas is: H2 30-35%, CO 35-40%, CO2 25-30%, CH4 <0.4%, and it is tar-free.

[0118] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A biomass gasification system, characterized in that, It includes a pressurized feeding unit (1), a fluidized bed gasification unit (2), a slag discharge unit (3), a high-temperature pyrolysis unit (4), a syngas washing unit (5), a slag-water unit (6), and a gasifying agent conveying unit; The fluidized bed gasification unit (2) includes a fluidized bed gasifier (21) and a high-temperature cyclone separator (22). The fluidized bed gasifier (21) is connected to a pressurized feeding unit (1), a gasifying agent conveying unit, a high-temperature cyclone separator (22), and a slag discharge unit (3). The high-temperature pyrolysis unit (4) of the fluidized bed includes a high-temperature pyrolysis furnace (41), which is connected to a high-temperature cyclone separator (22), a gasifying agent conveying unit, a syngas 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) includes a biomass bin (11), a biomass lock hopper (12), and a biomass delivery hopper (13) connected in sequence; The biomass lock hopper (12) is connected to the pressurized gas conveying 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 equipped with a biomass inlet, a gasifying agent inlet, a syngas outlet, a fly ash return outlet, and a slag discharge outlet; The biomass inlet is connected to the pressurized feeding unit (1), the gasifying agent inlet is connected to the gasifying agent conveying unit, the syngas outlet and fly ash return outlet are both connected to the high-temperature cyclone separator (22), and the slag discharge outlet 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) includes a slag discharge buffer tank (31), a slag lock hopper (32), and a slag bin (33) connected in sequence; The slag discharge buffer tank (31) is connected to the bottom of the fluidized bed gasifier (21).

5. The biomass gasification system according to claim 1, characterized in that, The fluidized bed high-temperature pyrolysis furnace (41) includes a burner (411), a radiant waste heat boiler (412), and a quench module (413) arranged from top to bottom; The burner (411) is connected to the high-temperature cyclone separator (22) and the gasifying agent conveying unit, the radiant waste heat boiler (412) is connected to the boiler water conveying unit and the steam output unit, and the quench module (413) is connected to the syngas scrubbing unit (5) and the slag water unit (6).

6. The biomass gasification system according to claim 5, characterized in that, The syngas scrubbing unit (5) includes a Venturi scrubber (51), a hydrocyclone separator (52), and a water scrubbing tower (53) connected in sequence; The Venturi scrubber (51) is connected to the quench module (413), the cyclone separator (52) is connected to the slag and water unit (6), and the water washing tower (53) is connected to the quench module (413), the slag and water unit (6), and the syngas output unit.

7. The biomass gasification system according to claim 6, characterized in that, The water washing tower (53) is equipped with a syngas inlet, a quench water return outlet, a slag water outlet, and an ash water inlet; The syngas inlet is connected to the cyclone separator (52), the quench water return port is connected to the high-temperature pyrolysis furnace (41), and the slag water outlet and 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 and water unit (6) is equipped with a black water inlet, a washing water inlet, and a grey water outlet; The black water inlet is connected to the high-temperature pyrolysis furnace (41) of the fluidized bed, and the washing water inlet and the ash water outlet are both connected to the syngas washing unit (5).

9. The biomass gasification system according to claim 1, characterized in that, The vaporizing agent delivery unit includes a storage tank containing pure oxygen / oxygen-enriched / air and vapor / CO2 and a delivery pipeline. The fluidized bed gasifier (21), the high-temperature cyclone separator (22), and the high-temperature pyrolysis furnace (41) are all equipped with refractory linings.

10. A biomass gasification method, characterized in that, Using the biomass gasification system according to any one of claims 1 to 9, the process includes the following steps: S1: Biomass is pressurized by the pressurized feeding unit (1) and then transported to the fluidized bed gasification unit (2); S2: Biomass reacts with gasifying agent in fluidized bed gasifier (21) to produce syngas. After dust removal by high temperature cyclone separator (22), crude syngas is formed. Bottom ash is discharged after cooling and depressurization by ash discharge unit (3). S3: After the crude syngas and gasifying agent are mixed in the high-temperature pyrolysis furnace (41) of the fluidized bed, tar and methane pyrolysis reaction occurs. The tar and methane in the crude syngas are converted into effective gases CO and H2 at high temperature. S4: The high-temperature pyrolysis gas after the pyrolysis reaction is washed by the syngas washing unit (5) to form dust removal syngas, and the black water generated by the washing enters the slag water unit (6).

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