Biomass fixed bed poly-generation system and working method

Abstract

The present invention discloses a biomass fixed bed poly-generation system, which comprises: a biomass gasification device in which carbon-containing biomass is gasified to form a synthesis gas containing CH4, CO, CO2 and H2; a gas phase outlet of the biomass gasification device is connected with a gas inlet pipeline of the methanol production device, and the synthesis gas is subjected to a synthesis reaction in the methanol production device to produce refined methanol and methanol residual liquid; the invention further discloses a working method of the biomass fixed bed poly-generation system, purge gas generated by the methanol synthesis device is used as fuel for power generation, the purge gas is used as fuel gas of the fuel gas power generation device, hot steam generated by the fuel gas power generation device is used for heating methanol residual liquid, and the fuel gas power generation device is used for generating fuel gas generated by the fuel gas power generation device. The residual methanol liquid is used as a gasifying agent to participate in biomass gasification reaction, so that system energy consumption and resource waste during preparation of methanol from biomass are reduced.

Description

Technical Field

[0001] The present invention relates to the field of fixed bed gasification technology, and more specifically, to a biomass fixed bed polygeneration system and a working method. Background Art

[0002] As global energy demand continues to grow, traditional fossil energy is increasingly depleted. Biomass energy, as a renewable energy source, has huge development potential. Biomass energy is a renewable energy source produced from plants, which is renewable and sustainable. Biomass resources are widely present in nature, including agricultural waste, forestry residues, urban domestic waste, etc. These resources can be transformed and utilized through biomass energy technology. Biomass energy will effectively alleviate the contradiction between the growing energy demand and limited fossil energy reserves.

[0003] The biomass gasification furnace for pyrolysis of biomass resources has the advantages of simple operation and easy feeding. Fixed-bed gasification furnaces are widely used in the coal chemical industry. Since the mixed gas after biomass gasification has a high content of carbon monoxide and methane, biomass gasification to methanol is regarded as a more economical route for producing methanol. However, the process system for biomass to methanol generally faces several problems. First of all, in addition to producing refined methanol, the process system for preparing methanol from biomass also produces waste liquids such as methanol residue and detergent. At present, the process links often only process the waste liquid produced by the process system, and do not give in-depth consideration to how to utilize it to avoid waste of resources. Secondly, the power generation of each equipment in the process link of biomass gasification to methanol depends entirely on the external power grid system. In addition to the high electricity cost, it does not meet the current intention for environmental protection and carbon reduction in industrial production.

[0004] The Chinese patent with authorization announcement number CN103899371B discloses a multi-generation system for producing methanol and generating electricity using biomass and solar energy. The system improves the effective utilization rate of biomass through a solar thermal collection reaction subsystem, a biomass gasification subsystem, a methanol synthesis subsystem and a power generation subsystem. However, the method does not take into account the processing of methanol residues, detergents, etc. in the biomass methanol production process, and additional processing equipment is still needed in the future.

[0005] Therefore, there is an urgent need for a process system that can produce methanol from biomass and has the ability to generate electricity, which can make full use of various products in the biomass pyrolysis and methanol production process to achieve the effect of energy conservation and emission reduction. Summary of the invention

[0006] An object of the present invention is to provide a biomass fixed-bed multi-generation system and a working method, which prepares methanol from biomass and has the ability to generate electricity. Various products in the biomass pyrolysis and methanol production process can be fully utilized, which has the beneficial effect of energy saving and efficiency improvement.

[0007] In order to achieve these purposes and other advantages according to the present invention, in a first aspect, the present invention provides a biomass fixed bed polygeneration system, comprising: a biomass gasification device, in which carbonaceous biomass is gasified to form CH 4 ,CO,CO 2 , H 2 The synthesis gas of the biomass gasification device is connected to the gas inlet pipeline of the methanol production device, and the synthesis gas is synthesized in the methanol production device to produce refined methanol and generate methanol residual liquid; a gas-fired power generation device, which uses the relaxation gas produced by the methanol synthesis device as fuel gas for power generation.

[0008] Preferably, the methanol production device includes a crude methanol synthesis device and a methanol distillation device, the gas inlet of the gas-fired power generation device is connected to the gas phase outlet pipeline of the crude methanol synthesis device, the purge gas separated from the crude methanol prepared by the crude methanol synthesis device enters the gas-fired power generation device, the crude methanol after exhaust enters the methanol distillation device for distillation to obtain refined methanol and generate methanol residue, the power output end of the gas-fired power generation device is electrically connected to the factory power grid, the methanol residue is heated by the steam of the gas-fired power generation device to form steam and is passed into the biomass gasification device to participate in the biomass gasification reaction.

[0009] Preferably, the gas phase outlet pipeline of the crude methanol synthesis unit is connected to a hydrogen extraction device, which separates the hydrogen in the relaxation gas, and the hydrogen extraction device is provided with a hydrogen outlet connected to the air inlet pipeline of the crude methanol production unit and a gas outlet connected to the gas inlet pipeline of the gas power generation unit.

[0010] Preferably, the biomass gasification device includes an air separation device and a biomass gasification furnace, the biomass gasification furnace includes a biomass feed inlet at the top, an ash outlet at the bottom, a gasification agent inlet at the lower part, and a synthesis gas outlet at the upper part, and the front-end pipeline of the gasification agent inlet is connected to the steam exhaust outlet of the gas-fired power generation device and the gas phase outlet of the air separation device.

[0011] Preferably, it also includes a synthesis gas washing device, which includes a scrubber, an oil washing tower and a separation tank connected by pipelines, the scrubber is provided with a first detergent inlet, a synthesis gas inlet and a first gas-liquid mixture outlet, and the synthesis gas inlet is connected to the synthesis gas outlet pipeline; the oil washing tower is provided with a gas-liquid mixture inlet, a detergent outlet, a second detergent inlet located at the top and a second gas-liquid mixture outlet located at the top, the gas-liquid mixture inlet is connected to the first gas-liquid mixture outlet pipeline, and the second gas-liquid mixture outlet pipeline is connected to the separation tank, and the separation tank separates the gas-liquid mixture entering therein into three phases according to gas phase, liquid phase and oil phase.

[0012] Preferably, the detergent outlet pipe is connected to the second detergent inlet and the first detergent inlet, the oil phase outlet pipe of the separation tank is connected to the second detergent inlet and the first detergent inlet, a detergent discharge port is provided at the bottom of the oil washing tower, and its pipe is connected to the feed port of the flash evaporator, and a liquid discharge port is provided at the lower part of the flash evaporator, which is connected to the sedimentation separator pipe.

[0013] Preferably, a gas stripping tower is further included, wherein the gas stripping tower is provided with a first material inlet and a second material inlet, an oxygen inlet and a water vapor inlet, a mixed gas outlet at the top and a sewage outlet at the bottom, the liquid phase outlet of the separation tank is connected to a filter, the drain outlet of the filter is connected to the second material inlet of the gas stripping tower, the top of the flash evaporator is provided with a gas phase outlet connected to the first material inlet pipeline, and the mixed gas outlet is connected to the front end of the gasifying agent inlet.

[0014] Preferably, it also includes a clean energy power generation device and an energy storage device, and the energy storage device, the clean energy power generation device, the gas power generation device and the in-plant power grid are electrically connected to each other.

[0015] Preferably, the biomass gasification furnace is provided with a membrane water-cooled wall insulation layer.

[0016] In a second aspect, the present invention provides a working method of a biomass fixed-bed polygeneration system, comprising the following steps:

[0017] S1. placing the treated biomass raw material in a biomass gasification device, introducing a gasifying agent composed of steam and oxygen to produce a chemical reaction, and the produced ash and synthesis gas are discharged from the biomass gasification device;

[0018] S2, using a mixture of wood vinegar and wood tar as a washing agent, quenching and washing the synthesis gas to remove dust and oil contained therein, and the washing agent with high dust content is flashed and settled in sequence to obtain clean and separated wood vinegar and wood tar;

[0019] S3, adjusting the ratio of carbon monoxide and hydrogen in the synthesis gas after removing dust and oil to meet the molar ratio requirement for methanol synthesis;

[0020] S4, compressing the synthesis gas to the pressure required for methanol synthesis to synthesize crude methanol, separating the purge gas in the crude methanol, extracting hydrogen from the purge gas to produce methane-rich gas and hydrogen, mixing the hydrogen into the synthesis gas in step S3, and the methane-rich gas entering the gas-fired power generation device;

[0021] S5, distilling the crude methanol after exhaust to obtain refined methanol and methanol residue;

[0022] S6. The methanol residue is introduced into a gas-fired power generation device and heated and evaporated using waste heat of power generation steam, and then enters a biomass gasification device as a part of the gasification agent.

[0023] The present invention has at least the following beneficial effects:

[0024] First, the biomass fixed bed polygeneration system of the present invention uses the relaxation gas mainly composed of methane in the methanol synthesis process as the fuel gas source for the gas-fired power generation device. The system itself can produce considerable electricity to power other devices in the system, thereby reducing the electricity cost of the system and appropriately reducing the cost of adding clean energy power generation equipment;

[0025] Second, the biomass fixed bed polygeneration system of the present invention utilizes the methanol residue produced in the methanol distillation step and the water discharged in the crude methanol synthesis step as one of the sources of steam gasification agent, which greatly reduces the demand for water vapor in the biomass gasification step;

[0026] Third, the detergent used in the present invention uses a mixture of wood tar and wood vinegar produced by self-gasification, and washes the synthesis gas multiple times through circulation, which can not only effectively wash away the ash in the synthesis gas, but also use oil washing for dust removal and purification of product gas to avoid the introduction of water washing water, and the sewage separated by condensation only comes from the water vapor in the synthesis gas, which greatly reduces the discharge of sewage and simplifies the difficulty of sewage treatment;

[0027] Fourth, the wood tar and wood vinegar mixture used as detergents in the present invention is discharged from the oil washing tower after the dust content reaches a certain level, and clean and separated wood vinegar and wood tar are obtained through flash evaporation and sedimentation. Wood tar can be used for biodiesel production, and wood vinegar can be used as a pesticide additive, soil conditioner, etc.

[0028] Fifth, in the biomass fixed bed polygeneration system of the present invention, the biomass gasification furnace is provided with a membrane water-cooled wall insulation layer, the water-cooled wall diaphragm is not under pressure during the modeling process, and temperature measuring points can be added to the membrane water-cooled wall diaphragm, thereby realizing precise control of the furnace temperature.

[0029] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a technical solution of the biomass fixed-bed polygeneration system of the present invention;

[0031] Figure 2 It is a schematic diagram of the synthesis gas washing device and upper and lower end equipment in a technical solution of the biomass fixed bed polygeneration system of the present invention.

[0032] Legend: 1-In-plant power grid, 2-Biomass gasification device, 20-Material lock hopper, 21-Biomass gasification furnace, 22-Air separation device, 211-Biomass feed inlet, 212-Gasifying agent inlet, 213-Synthesis gas outlet, 214-Ash outlet, 3-Synthesis gas washing device, 30-Scrubber, 301-First detergent inlet, 302-Synthesis gas inlet, 303-First gas-liquid mixture outlet, 31-Oil washing tower, 311-Gas-liquid mixture inlet, 312-Detergent discharge port, 313-Detergent outlet, 314-Second detergent inlet, 315-Second gas-liquid mixture outlet, 32-Separation tank, 33-Filter, 34-Gas stripping tower, 341-First material inlet, 342-second material inlet, 343-wastewater outlet, 344-mixed gas outlet, 35-flash evaporator, 36-sedimentation separator, 4-methanol production unit, 41-crude methanol synthesis unit, 411-first conversion furnace, 412-second conversion furnace, 413-gas-liquid separator, 414-gas purification sub-unit, 415-compressor unit, 416-methanol synthesis tower, 417-relaxation gas separator, 42-methanol distillation unit, 421-crude methanol storage tank, 422-pre-distillation tower, 423-pressurized distillation tower, 424-atmospheric distillation tower, 5-hydrogen extraction device, 51-hydrogen outlet, 52-gas outlet, 6-gas power generation unit, 7-clean energy power generation device, 8-energy storage device. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can implement the invention with reference to the description.

[0034] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0035] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the structures and components can be obtained from commercial sources unless otherwise specified; in the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected, set, or detachably connected, set, or connected and set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in specific circumstances. The orientation or position relationship indicated by the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0036] like Figures 1-2 As shown, the biomass fixed bed polygeneration system includes: a biomass gasification device 2, in which the carbon-containing biomass is gasified to form CH 4 ,CO,CO 2 , H 2 The synthesis gas of the methanol production device 4, wherein the gas phase outlet of the biomass gasification device 2 is connected to the gas inlet pipeline of the methanol production device 4, and the synthesis gas undergoes a synthesis reaction in the methanol production device 4 to produce refined methanol and generate methanol residual liquid; a gas-fired power generation device, which uses the relaxation gas produced by the methanol synthesis device 4 as fuel gas for power generation. In the present technical scheme, the biomass gasification device 2 includes a feed lock hopper 20 and a biomass gasifier 21. The biomass enters the biomass gasifier 21 through the feed lock hopper 20, and oxygen, steam and other substances are mixed and introduced into the biomass gasifier 21 as a gasifying agent. The gasifying agent reacts chemically with the biomass raw material at high temperature to generate ash and synthesis gas. Since the reaction temperature in the biomass gasifier 21 is lower than the decomposition temperature of substances such as tar, phenol, and ammonia, the synthesis gas contains CH 4 ,CO,CO 2 , H 2 , water vapor and tar and dust, the synthesis gas is cooled and washed before entering the methanol production unit 4.

[0037] In the present technical scheme, the gas-fired power generation device 6 includes a connected gas boiler and a steam turbine that are easily available or processed on the market. The methanol production device 4 uses carbon monoxide and hydrogen to react to produce methanol. The synthesis gas produced by the biomass gasification device 2 is successively transformed, purified, compressed, synthesized, and distilled in the methanol production device 4 to become refined methanol. During this process, the methane-rich relaxation gas produced in the crude methanol distillation link is collected and then enters the gas-fired power generation device 6 as fuel. The present technical scheme uses the relaxation gas mainly composed of methane in the methanol synthesis process as the fuel source for the gas-fired power generation device 6. The system itself can produce considerable electricity to power other devices in the system, thereby reducing the system's electricity cost.

[0038] In another technical solution, the methanol production device 4 includes a crude methanol synthesis device 41 and a methanol distillation device 42, the gas inlet of the gas-fired power generation device 6 is connected to the gas phase outlet pipeline of the crude methanol synthesis device 41, the purge gas separated from the crude methanol prepared by the crude methanol synthesis device 41 enters the gas-fired power generation device 6, the crude methanol after exhaust enters the methanol distillation device 42 for distillation to obtain refined methanol and generate methanol residual liquid, the power output end of the gas-fired power generation device 6 is electrically connected to the in-plant power grid 1, the methanol residual liquid is heated by the steam of the gas-fired power generation device 6 to form steam and is passed into the biomass gasification device 2 to participate in the biomass gasification reaction. The crude methanol synthesis device 41 comprises a first conversion furnace 411, a second conversion furnace 412, a gas-liquid separator 413, a gas purification sub-device 414, a compressor unit 415, a methanol synthesis tower 416, and a relaxation gas separator 417, which are sequentially connected by pipelines. In this process, carbon monoxide and hydrogen are reacted to produce methanol, so it is necessary to adjust the ratio of carbon monoxide and hydrogen before methanol synthesis to meet the ratio requirement of methanol synthesis. The methane component in the washed synthesis gas reacts with water vapor under the action of a catalyst in the first conversion furnace 411 and the second conversion furnace 412 to generate carbon monoxide and hydrogen. The hydrogen and carbon monoxide in the synthesis gas are adjusted to a suitable ratio and then sent to the gas purification sub-device 414 for desulfurization and decarbonization. The gas purification sub-device 414 can select the MDEA method or the low-temperature methanol washing method. After purification, the synthesis gas enters the compressor unit 415, and the pressure is increased to the pressure required for methanol synthesis and then sent to the methanol synthesis tower 416 for methanol synthesis. The crude methanol produced is removed from the internal relaxation gas in the relaxation gas separator 417 by flash evaporation or the like.

[0039] In the present technical scheme, the steam component in the gasifying agent introduced into the biomass gasification device 2 includes the steam generated by the methanol residue. The reaction by-products such as methanol, ethanol, higher alcohols, aldehydes and the incompletely reacted raw materials in the methanol residue can enter the biomass gasification device 2 with the steam for reaction. In this process, the methanol residue produced in the crude methanol distillation link and the wastewater when the relaxation gas is discharged are collected and heated by the high-temperature steam produced by the gas power generation device 6, and then sent to the biomass gasification device 2 as a steam gasifying agent, saving the corresponding residual liquid treatment and purification equipment. The biomass to methanol system in the present technical scheme uses the wastewater in the methanol preparation link as the source of steam in the gasifying agent. Compared with the conventional biomass to methanol system, the wastewater discharge is greatly reduced, the wastewater purification cost is low, the water consumption is saved, and the electricity cost of the system is reduced, which is more in line with the production concept of energy conservation and emission reduction.

[0040] In another technical solution, the gas phase outlet pipeline of the crude methanol synthesis device 41 is connected to a hydrogen extraction device 5, and the hydrogen extraction device 5 separates the hydrogen in the purge gas. The hydrogen extraction device 5 is provided with a hydrogen outlet 51 connected to the gas inlet pipeline of the crude methanol production device 41 and a gas outlet 52 connected to the gas inlet pipeline of the gas power generation device 6; in this technical solution, the purge gas separated by the purge gas separator 417 contains hydrogen and methane, and the hydrogen extraction device 5 is used to remove the hydrogen in the purge gas, firstly to avoid explosion. The extracted hydrogen enters the gas-fired power generation device 6, and the extracted hydrogen can be mixed with the washed synthesis gas again to improve the material utilization rate. Optionally, the hydrogen extraction device 5 uses a membrane material with selective permeability to allow hydrogen molecules to pass through the membrane layer preferentially, while other molecules are blocked on the other side of the membrane. The hydrogen that passes through the membrane layer is transported from the hydrogen outlet 51 along the pipeline to the front end of the crude methane production device 41 and mixed with the washed synthesis gas. The gas that does not pass through, mainly methane, is transported from the gas outlet 52 along the pipeline to the gas-fired power generation device 6.

[0041] In another technical solution, the biomass gasification device 2 includes an air separation device 22 and a biomass gasification furnace 21. The biomass gasification furnace 21 includes a biomass feed inlet 211 at the top, an ash outlet 214 at the bottom, a gasification agent inlet 212 at the bottom, and a synthesis gas outlet 213 at the top. The front end pipeline of the gasification agent inlet 212 is connected to the steam outlet of the gas power generation device 6 and the gas phase outlet of the air separation device 22. The air separation device 1 separates the various component gases in the air, and the subsequent reaction The corresponding oxygen and carbon dioxide are mixed with the steam produced by the gas power generation device 6 as a gasifying agent. The pretreated biomass raw material enters from the biomass feed port 211, and the gasifying agent enters from the gasifying agent inlet 212. The ash outlet 214 is downwardly connected to a lock bucket and an ash treatment system. The ash produced by the biomass raw material enters the ash treatment system from the ash outlet 214 for cooling and post-treatment. The synthesis gas after pyrolysis and gasification of the biomass raw material is discharged from the synthesis gas outlet 213, and enters the methanol production device 4 after cooling and dust removal.

[0042] In another technical solution, a synthesis gas washing device 3 is also included, which includes a scrubber 30, an oil washing tower 31 and a separation tank 32 connected by pipelines. The scrubber 30 is provided with a first detergent inlet 301, a synthesis gas inlet 302 and a first gas-liquid mixture outlet 303, and the synthesis gas inlet 302 is connected to the synthesis gas outlet 213 by pipeline; the oil washing tower 31 is provided with a gas-liquid mixture inlet 311, a detergent outlet 313, a second detergent inlet 314 located at the top and a second gas-liquid mixture outlet 315 located at the top, the gas-liquid mixture inlet 311 is connected to the first gas-liquid mixture outlet 303 by pipeline, and the second gas-liquid mixture outlet 315 is connected to the separation tank 32 by pipeline, and the separation tank 32 separates the gas-liquid mixture entering therein into three phases according to gas phase, liquid phase and oil phase. The detergent used in the synthesis gas washing device 3 is an oily substance. The detergent enters the scrubber 30 and the oil washing tower 31 through the first detergent inlet 301 and the second detergent inlet 314 respectively to remove the oil and dust in the synthesis gas, greatly reducing the amount of process wastewater and reducing the amount of sewage discharged.

[0043] In another technical solution, the detergent outlet 313 pipeline is connected to the second detergent inlet 314 and the first detergent inlet 301, the oil phase outlet pipeline of the separation tank 32 is connected to the second detergent inlet 314 and the first detergent inlet 301, and a detergent discharge port 312 is provided at the bottom of the oil washing tower 31, and its pipeline is connected to the feed port of the flash evaporator 35. The lower part of the flash evaporator 35 is provided with a liquid discharge port, which is connected to the sedimentation separator 36 pipeline, wherein the detergent is recycled in the scrubber 30, the oil washing tower 31 and the separation tank 32, further reducing the amount of liquid washing oil and the dust removal cost, and improving the energy utilization rate. The oil phase component separated by the separation tank 32 is also transported back to the scrubber 30 and the oil washing tower 31 as a detergent. Optionally, a pumping device and a cooling device such as a circulating pump can be installed on the corresponding pipelines.

[0044] In the present technical solution, the detergent is a mixture of wood tar and wood vinegar produced by the pyrolysis of the biomass raw material itself. The detergent with a high dust content at the bottom of the oil washing tower 31 is regularly discharged through the detergent discharge port 312, and after flash evaporation in the flash evaporator 35 to remove moisture, it enters the sedimentation separator 36, and after static stratification, the wood vinegar and wood tar as system by-products are separated.

[0045] In another technical solution, a stripping tower 34 is further included, wherein the stripping tower 34 is provided with a first material inlet 341 and a second material inlet 342 located at the top, an oxygen inlet and a water vapor inlet, a mixed gas outlet 344 located at the top, and a sewage outlet 343 located at the bottom. The liquid phase outlet of the separation tank 32 is connected to a filter 33, and the drain port of the filter 33 is connected to the second material inlet 342 of the stripping tower 34. The top of the flash evaporator 35 is provided with a gas phase outlet connected to the first material inlet 341 by a pipeline. The gas outlet 344 is connected to the front end of the gasifying agent inlet 212. In the present technical solution, the sewage output by the separation tank 32 and the steam generated by the flash evaporator 35 enter the gas stripping tower 34 into which oxygen and steam are introduced along the pipeline from the second material inlet 342 and the first material inlet 341 respectively for gas stripping, and then are discharged from the sewage outlet 343. The generated gas stripping mixed gas is transported from the mixed gas outlet 344 along the pipeline to the front end of the gasifying agent inlet, and is mixed with the steam discharged from the gas power generation device 6, the oxygen generated by the air separation device 1 and other components to form a gasifying agent.

[0046] In another technical solution, it also includes a clean energy power generation device 7 and an energy storage device 8. The energy storage device 8, the clean energy power generation device 7, the gas power generation device 6 and the in-plant power grid 1 are electrically connected to each other. In this technical solution, the clean energy power generation device 7 is a photovoltaic power generation device, a wind power generation device or a combination of the two power generation devices. The energy storage device 8 is in the form of mechanical energy storage, electromagnetic energy storage and chemical energy storage or a combination. The energy storage device 8 stores energy during the peak time period of the gas power generation device 6 and the clean energy power generation device 7, and supplies power to the in-plant power grid 1 during the power generation trough.

[0047] In another technical solution, the biomass gasifier 21 is provided with a membrane water-cooled wall insulation layer. In this technical solution, the biomass gasifier 21 adopts a pressure-bearing steel shell with a membrane water-cooled wall insulation layer. The membrane water-cooled wall insulation layer is not under pressure. Compared with the water interlayer method, a thermocouple can be installed on the membrane water-cooled wall insulation layer and inserted into the biomass gasifier 21 to accurately measure the temperature distribution of each layer in the furnace, thereby achieving accurate control of the furnace temperature and gas-oxygen ratio. Optionally, the steam generated by the membrane water-cooled wall insulation layer can also be introduced into the front end of the gasifying agent inlet 212 as a gasifying agent.

[0048] In another technical solution, the working method of the above-mentioned biomass fixed bed polygeneration system comprises the following steps:

[0049] S1. Place the processed biomass raw material in the biomass gasification device 1, and introduce a gasifying agent composed of steam and oxygen to produce a chemical reaction. The ash and synthesis gas produced are discharged from the biomass gasification device 2. Specifically, for biomass with smaller particle size, it can be briquette first and then sent to the material lock hopper 20. Optionally, a binder can be added to the biomass material to make it better shaped. The temperature in the biomass gasification furnace 21 is 1000-1200°C, and the operating pressure of the biomass gasification furnace 21 is 0.1-6.5MPa. The ash obtained by the reaction of the biomass raw material and the gasifying agent is discharged from the ash outlet 214, containing CH 4 ,CO,CO 2 , H 2 The synthesis gas containing , water vapor, tar and dust is discharged from the synthesis gas outlet 213.

[0050] S2. Using a mixture of wood vinegar and wood tar as a detergent, the synthesis gas is subjected to quench washing to remove dust and oil contained therein, and the detergent with high dust content is sequentially subjected to flash evaporation and sedimentation to obtain clean and separated wood vinegar and wood tar; specifically, the synthesis gas is sequentially subjected to the first and second quench washing with the detergent when passing through the scrubber 30 and the oil washing tower 31, and then enters the separation tank 32, and the dust and oil in the synthesis gas are discharged from the gas phase outlet of the separation tank 32, the detergent circulates in the scrubber 30 and the oil washing tower 31, and the oil washing tower 31 regularly discharges the detergent with high dust content after multiple cycles, and the detergent enters the sedimentation separator 36 after flash evaporation, and the wood vinegar and wood tar are separated after static stratification.

[0051] S3. Adjust the ratio of carbon monoxide and hydrogen in the synthesis gas after removing dust and oil to meet the molar ratio requirement of methanol synthesis; specifically, the synthesis gas enters the first conversion furnace 411 and the second conversion furnace 412 of the crude methanol synthesis unit 41, and the methane component in the synthesis gas reacts with water vapor under the action of the catalyst to generate carbon monoxide and hydrogen. The first conversion furnace 411 and the second conversion furnace 412 complete the step of converting the synthesis gas into the gas required for methanol synthesis, and adjust the hydrogen-carbon ratio of the synthesis gas to make it more suitable for the subsequent methanol synthesis reaction.

[0052] S4, compressing the synthesis gas to the pressure required for methanol synthesis to synthesize crude methanol, separating the relaxation gas in the crude methanol, extracting hydrogen from the relaxation gas to produce methane-rich gas and hydrogen, the hydrogen is mixed into the synthesis gas in step S3, and the methane-rich gas enters the gas-fired power generation device; specifically, the generated crude methanol removes the internal relaxation gas by flash evaporation or the like in the relaxation gas separator 417, the separated relaxation gas contains hydrogen and methane, the degassed crude methanol is discharged from the liquid phase outlet of the relaxation gas separator 417 to the methanol distillation device 42, the hydrogen separated from the relaxation gas in the hydrogen extraction device 5 is re-mixed into the washed synthesis gas, and other gases enter the gas-fired power generation device 6 as fuel gas.

[0053] S5. Distill the crude methanol after exhaust to obtain refined methanol and methanol residue; specifically, the methanol distillation device 6 includes a crude methanol storage tank 421, a pre-distillation tower 422, a pressure distillation tower 423, and an atmospheric distillation tower 424 which are sequentially connected by pipelines. The crude methanol is preliminarily separated in the pre-distillation tower 422 to remove dimethyl ether and other light component organic impurities, and is effectively separated from other components under the pressure and temperature of the pressure distillation tower 423. Methanol is completely separated from impurities such as water and heavy components in the atmospheric distillation tower 424, and the refined methanol after distillation is shipped out of the factory as a product. At the same time, the atmospheric distillation tower 424 produces methanol residue.

[0054] S6. The methanol residue is introduced into the gas power generation device and heated and evaporated using the waste heat of the power generation steam, and then enters the biomass gasification device 2 as a part of the gasification agent.

[0055] In a calculation example, the biomass raw material processed by the system is corn stalks. The specific information of the material composition of corn stalks is shown in Table 1. The main components of the syngas after the dust and oil are removed from the gasification of corn stalks are shown in Table 2:

[0056] For example, if the system processes 27 tons of biomass raw materials per hour, gasifying this weight of biomass raw materials requires 6700Nm 3 Oxygen and 23 tons of steam are used as gasification agents. During the biomass gasification process, the air separation unit 22 consumes 4400kWh of electricity per hour, and the biomass raw material can produce 5390Nm per hour. 3 The gas-fired power generation device 7 can generate 23,500 kWh of electricity per hour. The power generation of the gas-fired power generation device 7 can completely cover the electricity consumption of the air separation device 1. Compared with the conventional biomass fixed-bed methanol production system, this system reduces 17 tons of discharged waste liquid.

[0057] Table 1 Data on material composition of corn straw

[0058]

[0059] Table 2 Main components of synthesis gas

[0060] CO 33.17％ <![CDATA[H 2 ]]> 22.75％ <![CDATA[CO 2 ]]> 26.38％ <![CDATA[CH 4 ]]> 15.25％

[0061] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0062] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. Biomass fixed bed polygeneration system, characterized in that: include: A biomass gasification device, in which carbonaceous biomass is gasified to form a synthesis gas containing CH4, CO, CO2, and H2; A methanol production device, wherein the gas phase outlet of the biomass gasification device is connected to the gas inlet pipeline of the methanol production device, and the synthesis gas undergoes a synthesis reaction in the methanol production device to produce refined methanol and generate methanol residue; A gas-fired power generation device uses the off-gas produced by a methanol synthesis device as fuel gas for power generation.

2. The biomass fixed bed polygeneration system according to claim 1, characterized in that: The methanol production device includes a crude methanol synthesis device and a methanol distillation device. The gas inlet of the gas-fired power generation device is connected to the gas phase outlet pipeline of the crude methanol synthesis device. The purge gas separated from the crude methanol prepared by the crude methanol synthesis device enters the gas-fired power generation device. The crude methanol after exhaust enters the methanol distillation device for distillation to obtain refined methanol and generate methanol residue. The power output end of the gas-fired power generation device is electrically connected to the power grid in the factory. The methanol residue is heated by the steam of the gas-fired power generation device to form steam and is passed into the biomass gasification device to participate in the biomass gasification reaction.

3. The biomass fixed bed polygeneration system according to claim 2, characterized in that: The gas phase outlet pipeline of the crude methanol synthesis device is connected to a hydrogen extraction device, which separates the hydrogen in the relaxation gas. The hydrogen extraction device is provided with a hydrogen outlet connected to the air inlet pipeline of the crude methanol production device and a gas outlet connected to the gas inlet pipeline of the gas power generation device.

4. The biomass fixed bed polygeneration system according to claim 1, characterized in that: The biomass gasification device includes an air separation device and a biomass gasification furnace. The biomass gasification furnace includes a biomass feed inlet at the top, an ash outlet at the bottom, a gasifying agent inlet at the lower part, and a synthesis gas outlet at the upper part. The front end pipeline of the gasifying agent inlet is connected to the steam exhaust outlet of the gas power generation device and the gas phase outlet of the air separation device.

5. The biomass fixed bed polygeneration system according to claim 1, characterized in that: It also includes a synthesis gas washing device, which includes a scrubber, an oil washing tower and a separation tank connected by pipelines, the scrubber is provided with a first detergent inlet, a synthesis gas inlet and a first gas-liquid mixture outlet, and the synthesis gas inlet is connected to the synthesis gas outlet pipeline; The oil washing tower is provided with a gas-liquid mixture inlet, a detergent outlet, a second detergent inlet located at the top and a second gas-liquid mixture outlet located at the top, the gas-liquid mixture inlet is connected to the first gas-liquid mixture outlet pipe, the second gas-liquid mixture outlet pipe is connected to a separation tank, and the separation tank separates the gas-liquid mixture entering therein into three phases according to gas phase, liquid phase and oil phase.

6. The biomass fixed bed polygeneration system according to claim 5, characterized in that: The detergent outlet pipe is connected to the second detergent inlet and the first detergent inlet, the oil phase outlet pipe of the separation tank is connected to the second detergent inlet and the first detergent inlet, a detergent discharge port is provided at the bottom of the oil washing tower, and its pipe is connected to the feed port of the flash evaporator, and a liquid discharge port is provided at the lower part of the flash evaporator, which is connected to the sedimentation separator pipe.

7. The biomass fixed bed polygeneration system according to claim 6, characterized in that: It also includes a gas stripping tower, which is provided with a first material inlet and a second material inlet, an oxygen inlet and a water vapor inlet, a mixed gas outlet located at the top and a sewage outlet located at the bottom, the liquid phase outlet of the separation tank is connected to a filter, the drain port of the filter is connected to the second material inlet of the gas stripping tower, the top of the flash evaporator is provided with a gas phase outlet connected to the first material inlet pipeline, and the mixed gas outlet is connected to the front end of the gasifying agent inlet.

8. The biomass fixed bed polygeneration system according to claim 2, characterized in that: It also includes a clean energy power generation device and an energy storage device, and the energy storage device, the clean energy power generation device, the gas power generation device and the in-plant power grid are electrically connected to each other.

9. The biomass fixed bed polygeneration system according to claim 3, characterized in that: The biomass gasification furnace is provided with a membrane-type water-cooled wall insulation layer.

10. The working method of the biomass fixed bed polygeneration system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. placing the treated biomass raw material in a biomass gasification device, introducing a gasifying agent composed of steam and oxygen to produce a chemical reaction, and the produced ash and synthesis gas are discharged from the biomass gasification device; S2, using a mixture of wood vinegar and wood tar as a washing agent, quenching and washing the synthesis gas to remove dust and oil contained therein, and the washing agent with high dust content is flashed and settled in sequence to obtain clean and separated wood vinegar and wood tar; S3, adjusting the ratio of carbon monoxide and hydrogen in the synthesis gas after removing dust and oil to meet the molar ratio requirement for methanol synthesis; S4, compressing the synthesis gas to the pressure required for methanol synthesis to synthesize crude methanol, separating the purge gas in the crude methanol, extracting hydrogen from the purge gas to produce methane-rich gas and hydrogen, mixing the hydrogen into the synthesis gas in step S3, and the methane-rich gas entering the gas-fired power generation device; S5, distilling the crude methanol after exhaust to obtain refined methanol and methanol residue; S6. The methanol residue is introduced into a gas-fired power generation device and heated and evaporated using waste heat of power generation steam, and then enters a biomass gasification device as a part of the gasification agent.

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