Coal water slurry gasification system and method taking biomass as raw material

Abstract

The invention provides a coal water slurry gasification system and method taking biomass as a raw material, and belongs to the technical field of biomass green low-carbon utilization. The problem that high-temperature corrosion of equipment is caused in the biomass utilization process due to the fact that the chlorine content in biomass, especially crops, is high is solved. The system comprises a biomass pretreatment unit, a pulverization unit, a pulping unit, a gasification unit and a synthesis gas treatment unit which are connected in sequence. The method is mainly used for biomass treatment and resource utilization.

Description

Technical Field

[0001] The present invention belongs to the technical field of green and low-carbon utilization of biomass, and in particular relates to a water-coal slurry gasification system and method using biomass as raw material. Background Art

[0002] Among the many alternative energy sources, biomass energy has attracted much attention due to its many advantages such as renewability, low pollution and huge reserves. my country is rich in biomass resources, with an annual total output of about 4.53 billion tons, including about 790 million tons of crop straw, about 3.05 billion tons of livestock and poultry manure, about 340 million tons of forestry residues, about 300 million tons of domestic garbage, and about 50 million tons of other organic waste. At present, there are two main ways to utilize biomass resources: combustion and gasification. However, the chlorine content in biomass, especially in crops, is relatively high. Regardless of which method is used, high-temperature corrosion of equipment will occur during the biomass utilization process. If the chlorine in the biomass raw materials can be removed, the problem of high-temperature corrosion of equipment caused by high chlorine content during the biomass utilization process will be solved, and biomass can be utilized on a large scale, that is, a good biomass treatment method is provided. Summary of the invention

[0003] In view of this, the present invention aims to propose a water-coal slurry gasification system and method using biomass as raw material, so as to solve the problem of high-temperature corrosion of equipment caused by high chlorine content in biomass, especially crops, during biomass utilization.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a water-coal slurry gasification system using biomass as raw material, which includes a biomass pretreatment unit, a pulverizing unit, a slurrying unit, a gasification unit and a synthesis gas processing unit connected in sequence.

[0005] Furthermore, the biomass pretreatment unit includes a hopper, a belt conveyor, a vibrating screen, a drying furnace, a metal chain conveyor, a crusher and a silo which are connected in sequence, the feed port of the hopper inputs biomass raw materials, the discharge port of the hopper is connected to the feed end of the belt conveyor, the discharge end of the belt conveyor is connected to the feed end of the vibrating screen, the discharge end of the vibrating screen is connected to the feed end of the drying furnace, the discharge end of the drying furnace is connected to the feed end of the metal chain conveyor, the discharge end of the metal chain conveyor is connected to the inlet of the crusher, and the outlet of the crusher is connected to the silo.

[0006] Furthermore, the powder making unit includes a feeder, an anaerobic pyrolysis furnace, a carbon powder separator and a carbon powder bin which are connected in sequence, the feed end of the feeder inputs the biomass crushed material in the biomass pretreatment unit bin, the discharge end of the feeder is connected to the feed port of the anaerobic pyrolysis furnace, the discharge port of the anaerobic pyrolysis furnace is connected to the inlet of the carbon powder separator, and the outlet of the carbon powder separator is connected to the carbon powder bin.

[0007] Furthermore, the pulping unit includes a pulping reaction device, a multi-stage elution and separation device and a water-coal slurry storage tank which are connected in sequence. The feed end of the pulping reaction device inputs the carbon powder in the carbon powder bin of the powder making unit, the discharge end of the pulping reaction device is connected to the inlet of the multi-stage elution and separation device, and the water-coal slurry outlet of the multi-stage elution and separation device is connected to the feed port of the water-coal slurry storage tank.

[0008] Furthermore, the pulping unit also includes a washing liquid purification device, and the washing liquid outlet of the multi-stage elution and separation device is connected to the inlet of the washing liquid purification device.

[0009] Furthermore, the gasification unit includes a coal slurry pump, a preheater, a gasifier, a radiation waste boiler and a convection waste boiler connected in sequence, the feed end of the coal slurry pump inputs the water-coal slurry in the water-coal slurry storage tank of the slurry making unit, the discharge end of the coal slurry pump is connected to the feed end of the preheater, the discharge end of the preheater is connected to the burner of the gasifier, the outlet of the synthesis gas of the gasifier is connected to the inlet of the radiation waste boiler, and the outlet of the synthesis gas of the radiation waste boiler is connected to the inlet of the convection waste boiler.

[0010] Furthermore, the gasification unit further comprises a slag lock hopper, and the gasification slag discharge end of the radiation waste boiler is connected to the slag lock hopper.

[0011] Furthermore, the synthesis gas processing unit includes a dry dust removal device, a water scrubber, a cooling and dehydration device and a desulfurization tower which are connected in sequence, the air inlet of the dry dust removal device is connected to the synthesis gas outlet of the convection waste boiler of the gasification unit, the air outlet of the dry dust removal device is connected to the air inlet of the water scrubber, the air outlet of the water scrubber is connected to the air inlet of the cooling and dehydration device, and the air outlet of the cooling and dehydration device is connected to the air inlet of the desulfurization tower.

[0012] The present invention also provides a method for a water-coal slurry gasification system using biomass as raw material, which comprises the following steps:

[0013] Step 1: Bulk biomass raw materials are used to enter the biomass pretreatment unit. The bulk biomass in the hopper falls into the feeding end of the belt conveyor from the hopper outlet by gravity, and is transported to the vibrating screen by the belt conveyor. The bulk biomass vibrates at a high frequency in the vibrating screen, and soil blocks, bricks and other debris are separated from the biomass. The separated debris is removed, and the biomass after impurities are sent to a drying furnace at 120 to 150°C for drying. The drying heat source adopts saturated steam produced by the waste heat recovery of crude synthesis gas from the gasification unit. The dried biomass is sent to the crusher through a metal chain conveyor for crushing, and the crushed biomass is crushed to obtain biomass crushed materials with a size of less than or equal to 10 cm, and the crushed materials are sent to the crushing bin;

[0014] Step 2: The crushed material from the crushing bin of the biomass pretreatment unit enters the milling unit, and the biomass crushed material in the crushing bin is sent to the anaerobic pyrolysis furnace through the feeder. The anaerobic pyrolysis temperature is controlled at 270°C to 300°C. The heat source adopts the saturated steam produced by the waste heat recovery of the crude synthesis gas in the gasification unit. The crushed material is pyrolyzed in the anaerobic pyrolysis furnace to obtain a solid particle product mainly composed of coke. The solid particle pyrolysis product is transported to the carbon powder separator by pneumatic conveying to separate the carbon powder, and the separated biomass carbon powder is sent to the carbon powder bin;

[0015] Step 3: the carbon powder material from the carbon powder bin of the pulverizing unit enters the pulping unit, the biomass carbon powder in the carbon powder bin is stirred and mixed with water in the pulping reaction device, the water in the stirring and mixing process of the carbon powder and water is deionized water, a naphthalenesulfonic acid formaldehyde condensate dispersant is added to form a water-coal slurry, the water-coal slurry is sent to a multi-stage elution separation device, the water-coal slurry is subjected to a multi-stage dechlorination separation treatment with water to obtain a water wash and a water-coal slurry, the water wash is sent to a water wash purification device, and the water-coal slurry is sent to a water-coal slurry storage tank;

[0016] Step 4: The water-coal slurry from the water-coal slurry storage tank of the pulping unit enters the gasification unit, the water-coal slurry is pressurized to 5Mpa by a coal slurry pump, and sent to the preheater pipeline, the water-coal slurry in the pipeline is heated to 120°C in the preheater, the heat source of the preheater adopts the saturated steam produced by the waste heat recovery of the crude synthesis gas of the gasification unit, the heated water-coal slurry is sent to the gasifier burner, the gasifier burner adopts a multi-nozzle opposed arrangement, the gasifier used is pure oxygen with a pressure of 5Mpa and a temperature of 25°C, which is the oxygen prepared by the electrolytic water device, the gasification pressure in the gasifier is 4.5MPa, the gasification temperature is 1300°C, the water-coal slurry and the gasifier undergo partial oxidation reaction in the gasifier, and the high-temperature crude synthesis gas produced by the gasifier carries the molten slag and ash into the lower part of the gasifier The high-temperature sensible heat is recovered in the radiation waste boiler, the temperature of the crude synthesis gas is reduced from 1300℃ to 600℃, and 8.1Mpa saturated steam is produced as a by-product. At the same time, the circulating synthesis gas of the synthesis gas treatment unit is sprayed into the radiation waste boiler inlet to quench it. The crude synthesis gas at the radiation waste boiler synthesis gas outlet carries a small amount of solid fly ash into the convection waste boiler for further heat recovery. The temperature of the crude synthesis gas is reduced to 300℃, and 5Mpa saturated steam is produced as a by-product. Most of the ash and slag entrained in the crude synthesis gas of the radiation waste boiler enter the slag lock bucket at the bottom of the radiation waste boiler from the gasification slag outlet of the radiation waste boiler under the action of gravity sedimentation and are discharged. The radiation waste boiler and the convection waste boiler together constitute a waste heat boiler. Part of the steam generated by the waste heat boiler is used for the system itself, and the rest is supplied to the outside.

[0017] Step 5: The crude synthesis gas from the convection waste boiler of the gasification unit enters the synthesis gas treatment unit, and the remaining solid particles and chlorine in the crude synthesis gas are removed by a dry dust removal device and a water scrubber. The crude synthesis gas containing saturated water after washing leaves the top of the water scrubber and is divided into two parts. One part is sent to the cooling and dehydration device as the product gas, and after cooling and dehydration by the cooling and dehydration device and desulfurization in the desulfurization tower, a clean synthesis gas is obtained, and the other part of the dechlorinated synthesis gas is sent to the radiation waste boiler of the gasification unit as quenching gas.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention provides a water-coal slurry gasification system and method using biomass as raw material. Relying on the water-coal slurry gasification technology, the biomass is decontaminated and crushed, and then anaerobic pyrolysis is performed to form carbon powder, which is then stirred and mixed with water to form water-coal slurry for gasification, thereby realizing large-scale biomass gasification utilization;

[0020] 2. The present invention provides a water-coal slurry gasification system and method using biomass as raw material, which uses water washing to perform multi-stage dechlorination treatment on the carbon powder product of biomass anaerobic pyrolysis, thereby solving the problem of equipment corrosion caused by high chlorine content in the process of biomass utilization and improving the stability of gasification equipment;

[0021] 3. The present invention provides a water-coal slurry gasification system and method using biomass as raw material. The heat source in the system adopts saturated steam produced by recovering the waste heat of crude synthesis gas after gasification. It not only does not need to be connected to the external power grid, but also can supply steam externally, thereby ensuring that the energy of the entire process is green energy and realizing green and low-carbon utilization of biomass. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of the overall structure of a water-coal slurry gasification system using biomass as raw material according to the present invention;

[0024] Figure 2 This is a schematic structural diagram of a biomass pretreatment unit in a water-coal slurry gasification system using biomass as a raw material according to the present invention;

[0025] Figure 3 This is a schematic structural diagram of a pulverizing unit in a water-coal slurry gasification system using biomass as raw material according to the present invention;

[0026] Figure 4 It is a structural schematic diagram of a pulping unit in a water-coal slurry gasification system using biomass as raw material according to the present invention;

[0027] Figure 5 It is a structural schematic diagram of a gasification unit in a water-coal slurry gasification system using biomass as raw material according to the present invention;

[0028] Figure 6 This is a schematic structural diagram of a synthesis gas processing unit in a water-coal slurry gasification system using biomass as raw material according to the present invention.

[0029] 1-hopper, 2-belt conveyor, 3-vibrating screen, 4-drying furnace, 5-metal chain conveyor, 6-crusher, 7-silo, 8-connecting feeder, 9-anaerobic pyrolysis furnace, 10-carbon powder separator, 11-carbon powder bin, 12-pulping reaction device, 13-multi-stage elution separation device, 14-water-coal slurry storage tank, 15-water washing liquid purification device, 16-coal slurry pump, 17-preheater, 18-gasification furnace, 19-radiation waste boiler, 20-convection waste boiler, 21-slag lock hopper, 22-dry dust removal device, 23-water washing tower, 24-cooling and dehydration device, 25-desulfurization tower. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0031] See also Figure 1-6 The present embodiment is described as a water-coal slurry gasification system using biomass as raw material, which includes a biomass pretreatment unit, a pulverizing unit, a slurrying unit, a gasification unit and a synthesis gas processing unit which are connected in sequence.

[0032] The biomass pretreatment unit described in this embodiment is used to remove impurities, dry and crush the biomass raw materials to obtain biomass crushed materials and store them.

[0033] The biomass pretreatment unit in this embodiment includes a hopper 1, a belt conveyor 2, a vibrating screen 3, a drying furnace 4, a metal chain plate conveyor 5, a crusher 6 and a silo 7 connected in sequence. The feed port of the hopper 1 inputs biomass raw materials, the discharge port of the hopper 1 is connected to the feed end of the belt conveyor 2, the discharge end of the belt conveyor 2 is connected to the feed end of the vibrating screen 3, the discharge end of the vibrating screen 3 is connected to the feed end of the drying furnace 4, the discharge end of the drying furnace 4 is connected to the feed end of the metal chain plate conveyor 5, the discharge end of the metal chain plate conveyor 5 is connected to the inlet of the crusher 6, and the outlet of the crusher 6 is connected to the silo 7. The biomass raw materials enter the system in bulk form and first enter the hopper 1. The design of the hopper 1 is convenient for the biomass bulk to rely on gravity and naturally fall from its discharge port into the feed end of the belt conveyor 2. The belt conveyor 2 stably transports the biomass bulk to the vibrating screen 3. Vibrating screen 3 produces a powerful screening effect through high-frequency vibration, which can effectively separate dirt, bricks and other debris from biomass. In the actual operation process, the mesh aperture of vibrating screen 3 is selected to ensure that it can not only efficiently separate debris, but also prevent excessive loss of qualified biomass particles. The separated debris is removed in time to prevent it from entering the subsequent process and affecting product quality and equipment operation. The biomass after de-impurity is sent to the drying furnace 4 for drying. The temperature of the drying furnace 4 is strictly controlled at 120 to 150°C. This temperature range can ensure that the water in the biomass is effectively evaporated, and the composition of the biomass will not change unnecessarily due to excessive temperature. It is worth mentioning that the drying heat source uses saturated steam produced by recovering the waste heat of the crude synthesis gas from the gasification unit, which not only realizes the efficient use of energy, but also greatly reduces the operating cost of the system, reflecting the concept of green and low carbon. Inside the drying furnace 4, through reasonable airflow design and heat exchange structure, the biomass can be fully in contact with the hot steam to ensure uniform drying effect. The dried biomass is smoothly sent to the crusher 6 by the metal chain conveyor 5. The crusher 6 crushes the biomass according to the pre-set parameters, and finally obtains biomass crushed materials with a size less than or equal to 10 cm. These crushed materials are then sent to the silo 7 for storage. The capacity of the silo 7 is reasonably designed according to the production scale of the system, which can continuously and stably supply biomass crushed materials to the subsequent milling unit.

[0034] The powder making unit described in this embodiment is used to perform anaerobic pyrolysis of biomass crushed materials and separate solid products to obtain carbon powder and store it.

[0035] The milling unit in this embodiment includes a feeder 8, an anaerobic pyrolysis furnace 9, a carbon powder separator 10 and a carbon powder bin 11 connected in sequence. The feed end of the feeder inputs the biomass crushed material in the biomass pretreatment unit bin 7, the discharge end of the feeder is connected to the feed port of the anaerobic pyrolysis furnace 9, the discharge port of the anaerobic pyrolysis furnace 9 is connected to the inlet of the carbon powder separator 10, the outlet of the carbon powder separator 10 is connected to the carbon powder bin 11, and the biomass crushed material from the biomass pretreatment unit bin 7 is uniformly fed into the anaerobic pyrolysis furnace 9 through the feeder 8. The anaerobic pyrolysis furnace 9 is the core equipment of the entire milling unit. The pyrolysis reaction inside it is carried out in an anaerobic environment, which effectively avoids the combustion of biomass and ensures that the pyrolysis products are mainly solid particle products mainly composed of coke. The pyrolysis temperature is strictly controlled at 270°C to 300°C. This temperature range has been verified by experiments and practice to ensure that the pyrolysis reaction is fully carried out and the quality of the carbon powder is optimized. The heat source of the anaerobic pyrolysis furnace 9 also uses saturated steam produced by the waste heat recovery of the crude synthesis gas from the gasification unit, realizing the recycling of energy. The solid particle products produced by pyrolysis are transported to the carbon powder separator 10 by pneumatic conveying. The carbon powder separator 10 uses a special separation principle to accurately separate carbon powder from other solid particles. The volume average particle size of the separated carbon powder is about 300μm, which meets the requirements of subsequent pulping. The separated biomass carbon powder is sent to the carbon powder bin 11 for storage. The carbon powder bin 11 has good sealing and storage conditions, which can effectively prevent the carbon powder from moisture and oxidation.

[0036] The pulping unit described in this embodiment is used to stir and mix carbon powder and water, and perform dechlorination and slurry separation treatment to obtain water-coal slurry and store it.

[0037] The pulping unit in this embodiment includes a pulping reaction device 12, a multi-stage elution separation device 13 and a water-coal slurry storage tank 14 connected in sequence. The feed end of the pulping reaction device 12 inputs the carbon powder in the carbon powder bin 11 of the pulverizing unit, the discharge end of the pulping reaction device 12 is connected to the inlet of the multi-stage elution separation device 13, the water-coal slurry outlet of the multi-stage elution separation device 13 is connected to the feed inlet of the water-coal slurry storage tank 14, and the carbon powder from the carbon powder bin 11 of the pulverizing unit enters the pulping reaction device 12. In the pulping reaction device 12, the carbon powder is stirred and mixed with water. In order to ensure the performance of the water-coal slurry, deionized water is used in the stirring process, and a naphthalenesulfonic acid formaldehyde condensate dispersant is added at the same time. This dispersant can effectively reduce the agglomeration phenomenon between carbon powder particles, so that carbon powder is evenly dispersed in water to form a water-coal slurry with stable performance. The water-coal slurry is sent to a multi-stage elution separation device 13. In the multi-stage elution separation device 13, the water-coal slurry is subjected to a multi-stage dechlorination separation treatment by multiple water washings. This process utilizes the solubility of chlorine in water. By repeated water washings, the chlorine content in the water-coal slurry is reduced to an extremely low level, effectively solving the problem of equipment corrosion caused by high chlorine content in the biomass utilization process. After multi-stage elution separation, water washing liquid and water-coal slurry are obtained. The water-coal slurry is sent to a water-coal slurry storage tank 14 for storage. The design of the water-coal slurry storage tank 14 can ensure that the water-coal slurry will not precipitate, deteriorate, etc. during storage, and is convenient for subsequent transportation to the gasification unit. The prepared water-coal slurry concentration is about 62%. This concentration is optimized to ensure the fluidity of the water-coal slurry and meet the requirements of the gasification reaction.

[0038] The pulping unit described in this embodiment also includes a water washing liquid purification device 15. The water washing liquid outlet of the multi-stage elution and separation device 13 is connected to the inlet of the water washing liquid purification device 15. The water washing liquid is sent to the water washing liquid purification device 15 for purification to remove impurities and harmful substances therein so as to be subsequently recycled or discharged in compliance with standards.

[0039] The gasification unit described in this embodiment is used to preheat the water-coal slurry and then perform pure oxygen gasification to obtain a crude synthesis gas, and to perform radiation heat exchange and convection heat exchange waste heat recovery treatment on the crude synthesis gas produced by gasification.

[0040] The gasification unit in this embodiment includes a coal slurry pump 16, a preheater 17, a gasifier 18, a radiation waste boiler 19 and a convection waste boiler 20 which are connected in sequence. The feed end of the coal slurry pump 16 inputs the water-coal slurry in the water-coal slurry storage tank 14 of the pulping unit, the discharge end of the coal slurry pump 16 is connected to the feed end of the preheater 17, the discharge end of the preheater 17 is connected to the burner of the gasifier 18, the outlet of the synthesis gas of the gasifier 18 is connected to the inlet of the radiation waste boiler 19, and the outlet of the synthesis gas of the radiation waste boiler 19 is connected to the inlet of the convection waste boiler 20. The water-coal slurry from the water-coal slurry storage tank 14 of the pulping unit is first pressurized to 5Mpa by the coal slurry pump 16. The high pressure can enable the water-coal slurry to better enter the subsequent equipment and participate in the reaction. The pressurized water-coal slurry is sent to the preheater 17 pipeline, where the water-coal slurry is heated to 120°C. The heat source of the preheater 17 adopts saturated steam produced by the waste heat recovery of the crude synthesis gas of the gasification unit, which realizes efficient utilization of energy. The heated water-coal slurry is sent to the burner of the gasifier 18. The burner of the gasifier 18 adopts a multi-nozzle opposed arrangement. This arrangement can fully mix the water-coal slurry and the gasification agent to improve the reaction efficiency. The gasification agent is pure oxygen with a pressure of 5Mpa and a temperature of 25°C, which is prepared by an electrolytic water device. In the gasifier 18, the gasification pressure is 4.5MPa and the gasification temperature is as high as 1300°C. Under such high temperature and high pressure conditions, the water-coal slurry and the gasification agent undergo partial oxidation reaction to generate high-temperature crude synthesis gas, and carry molten slag and ash. The high-temperature crude synthesis gas generated by the gasifier 18 carries the molten slag and ash into the radiation waste pot 19 at the bottom of the gasifier 18. The radiation waste boiler 19 is an important waste heat recovery equipment. It uses the sensible heat of the high-temperature raw synthesis gas to quickly reduce the temperature of the raw synthesis gas from 1300℃ to 600℃, and produces 8.1Mpa saturated steam as a by-product. In order to further reduce the temperature of the raw synthesis gas at the inlet of the radiation waste boiler 19 and protect the equipment at the same time, the circulating synthesis gas of the synthesis gas treatment unit is sprayed into the inlet of the radiation waste boiler 19 to quench it. The raw synthesis gas at the synthesis gas outlet of the radiation waste boiler 19 carries a small amount of solid fly ash. These raw synthesis gases enter the convection waste boiler 20, which further recovers the heat of the raw synthesis gas, reduces its temperature to 300℃, and produces 5Mpa saturated steam as a by-product. The radiation waste boiler 19 and the convection waste boiler 20 together constitute a waste heat boiler. Part of the steam generated by the waste heat boiler is used for the system itself to meet the energy needs of other equipment in the system, and the rest is supplied to the outside, realizing the comprehensive utilization of energy. Most of the ash and slag entrained in the raw synthesis gas of the radiation waste boiler 19 are discharged from the gasification molten slag outlet of the radiation waste boiler 19 into the slag lock hopper 21 at the bottom of the radiation waste boiler 19 under the action of gravity sedimentation. The design of the slag lock hopper 21 can effectively seal to prevent gas leakage and facilitate regular slag discharge.

[0041] In this embodiment, the gasification unit further includes a slag lock hopper 21 , and the gasification molten slag discharge end of the radiation waste boiler 19 is connected to the slag lock hopper 21 .

[0042] The synthesis gas processing unit described in this embodiment is used to perform dust removal, dechlorination, dehydration and desulfurization treatment on the raw synthesis gas to obtain clean synthesis gas.

[0043] The synthesis gas processing unit in this embodiment includes a dry dust removal device 22, a water scrubber 23, a cooling and dehydrating device 24 and a desulfurization tower 25 connected in sequence, the air inlet of the dry dust removal device 22 is connected to the synthesis gas outlet of the gasification unit convection waste boiler 20, the air outlet of the dry dust removal device 22 is connected to the air inlet of the water scrubber 23, the air outlet of the water scrubber 23 is connected to the air inlet of the cooling and dehydrating device 24, the air outlet of the cooling and dehydrating device 24 is connected to the air inlet of the desulfurization tower 25, the crude synthesis gas from the gasification unit convection waste boiler 20 first enters the dry dust removal device 22, and the dry dust removal device 22 uses the principles of filtration, electrostatics, etc. to effectively remove the remaining solid particles in the crude synthesis gas. The crude synthesis gas after dry dust removal enters the water scrubber 23, and the water scrubber 23 further removes chlorine in the crude synthesis gas by water washing, and can also remove some other impurities. In the water scrubber 23, through reasonable tower structure design and water flow distribution, it is ensured that the crude synthesis gas is fully in contact with water, and the dechlorination effect is improved. After washing, the crude synthesis gas containing saturated water leaves the top of the water scrubber 23 and is divided into two parts. One part is sent to the cooling and dehydration device 24 as product gas. The cooling and dehydration device 24 removes the moisture in the synthesis gas by cooling, condensation, etc., so that it reaches the specified water content standard. The synthesis gas after cooling and dehydration enters the desulfurization tower 25 for desulfurization treatment. The desulfurization tower 25 uses a suitable desulfurizer to reduce the sulfur content in the synthesis gas to an extremely low level, and obtains clean synthesis gas, which can be used as a product output. The other part of the dechlorinated synthesis gas is sent to the radiation waste boiler 19 of the gasification unit as quenching gas, which is used to reduce the temperature of the crude synthesis gas at the inlet of the radiation waste boiler 19, realize the recycling of gas, and improve the overall efficiency of the system.

[0044] This embodiment also provides a method for a water-coal slurry gasification system using biomass as raw material, which comprises the following steps:

[0045] Step 1: Bulk biomass raw materials are used to enter the biomass pretreatment unit. The bulk biomass in the hopper 1 falls into the feeding end of the belt conveyor 2 from the discharge port of the hopper 1 by gravity, and is transported to the vibrating screen 3 through the belt conveyor 2. The bulk biomass vibrates at a high frequency in the vibrating screen 3, and debris such as soil and bricks are separated from the biomass. The separated debris is removed, and the biomass after impurities are sent to a drying furnace 4 at 120 to 150° C. for drying. The drying heat source adopts saturated steam produced by recovering the waste heat of the crude synthesis gas from the gasification unit. The dried biomass is sent to the crusher 6 through the metal chain conveyor 5 for crushing, and the crushed biomass is crushed to obtain biomass crushed materials with a size of less than or equal to 10 cm, and the crushed materials are sent to the crushing bin 7;

[0046] Step 2: The crushed material from the crushing bin 7 of the biomass pretreatment unit enters the milling unit, and the crushed biomass in the crushing bin 7 is fed into the anaerobic pyrolysis furnace 9 through a feeder. The anaerobic pyrolysis temperature is controlled at 270°C to 300°C. The heat source is the saturated steam produced by the waste heat recovery of the crude synthesis gas in the gasification unit. The crushed material is pyrolyzed in the anaerobic pyrolysis furnace 9 to obtain a solid particle product mainly composed of coke. The solid particle pyrolysis product is transported to the carbon powder separator 10 by pneumatic conveying to separate the carbon powder. The volume average particle size of the separated carbon powder is about 300 μm, and the separated biomass carbon powder is fed into the carbon powder bin 11;

[0047] Step 3: the carbon powder material from the carbon powder bin 11 of the pulverizing unit enters the pulping unit, the biomass carbon powder in the carbon powder bin 11 is stirred and mixed with water in the pulping reaction device 12, the water in the stirring and mixing process of the carbon powder and water is deionized water, a naphthalenesulfonic acid formaldehyde condensate dispersant is added to form a water-coal slurry, the water-coal slurry is sent to a multi-stage elution separation device 13, the water-coal slurry is subjected to a multi-stage dechlorination separation treatment with water to obtain a water wash liquid and a water-coal slurry, the water wash liquid is sent to a water wash liquid purification device 15, and the water-coal slurry is sent to a water-coal slurry storage tank 14, and the prepared water-coal slurry has a concentration of about 62%;

[0048] Step 4: The water-coal slurry from the water-coal slurry storage tank 14 of the pulping unit enters the gasification unit, the water-coal slurry is pressurized to 5Mpa by the coal slurry pump 16, and sent to the preheater 17 pipeline, the water-coal slurry in the pipeline is heated to 120°C in the preheater 17, the heat source of the preheater 17 adopts the saturated steam produced by the waste heat recovery of the crude synthesis gas of the gasification unit, and the heated water-coal slurry is sent to the burner of the gasifier 18, the burner of the gasifier 18 adopts a multi-nozzle opposed arrangement, the gasifying agent used is pure oxygen with a pressure of 5Mpa and a temperature of 25°C, which is oxygen prepared by the electrolytic water device, the gasification pressure in the gasifier 18 is 4.5MPa, the gasification temperature is 1300°C, the water-coal slurry and the gasifying agent undergo partial oxidation reaction in the gasifier 18, and the high-temperature crude synthesis gas produced by the gasifier 18 carries the molten slag and ash into the lower part of the gasifier 18 The high-temperature sensible heat is recovered in the radiation waste boiler 19 of the waste boiler, the temperature of the crude synthesis gas is reduced from 1300°C to 600°C, and 8.1Mpa saturated steam is produced as a by-product. At the same time, the circulating synthesis gas of the synthesis gas treatment unit is sprayed into the inlet of the radiation waste boiler 19 to quench it. The crude synthesis gas at the synthesis gas outlet of the radiation waste boiler 19 carries a small amount of solid fly ash into the convection waste boiler 20 for further heat recovery. The temperature of the crude synthesis gas is reduced to 300°C, and 5Mpa saturated steam is produced as a by-product. Most of the ash and slag entrained in the crude synthesis gas of the radiation waste boiler 19 enter the slag lock hopper 21 at the bottom of the radiation waste boiler 19 from the gasification slag outlet of the radiation waste boiler 19 under the action of gravity sedimentation and are discharged. The radiation waste boiler 19 and the convection waste boiler 20 together constitute a waste heat boiler. Part of the steam generated by the waste heat boiler is used for the system itself, and the rest is supplied to the outside.

[0049] Step 5: The crude synthesis gas from the convection waste boiler 20 of the gasification unit enters the synthesis gas treatment unit, and the remaining solid particles and chlorine in the crude synthesis gas are removed by the dry dust removal device 22 and the water washing tower 23. The crude synthesis gas containing saturated water after washing leaves the top of the water washing tower 23 and is divided into two parts. One part is sent to the cooling and dehydration device 24 as the product gas, and after cooling and dehydration by the cooling and dehydration device 24 and desulfurization by the desulfurization tower 25, a clean synthesis gas is obtained, and the other part of the dechlorinated synthesis gas is sent to the radiation waste boiler 19 of the gasification unit as the quenching gas.

[0050] This embodiment relies on the water-coal slurry gasification technology to remove impurities and crush the biomass, then pyrolyze it into carbon powder in anoxic conditions, and then mix it with water to make water-coal slurry for gasification, so as to achieve large-scale biomass gasification utilization.

[0051] This embodiment uses a water washing method to perform multi-stage dechlorination treatment on the carbon powder product of biomass anaerobic pyrolysis, which solves the problem of equipment corrosion caused by high chlorine content during biomass utilization and improves the stability of gasification equipment

[0052] In this embodiment, the heat source in the system adopts saturated steam produced by recovering the waste heat of the crude synthesis gas after gasification. Not only does it not need to be connected to the external power grid, but it can also supply steam externally, thereby ensuring that the energy of the entire process is green energy and realizing green and low-carbon utilization of biomass.

[0053] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A water-coal slurry gasification system using biomass as raw material, characterized by: The utility model comprises a biomass pretreatment unit, a powder making unit, a pulping unit, a gasification unit and a synthesis gas processing unit which are connected in sequence.

2. A water-coal slurry gasification system using biomass as raw material according to claim 1, characterized in that: The biomass pretreatment unit comprises a hopper (1), a belt conveyor (2), a vibrating screen (3), a drying furnace (4), a metal chain plate conveyor (5), a crusher (6) and a silo (7) which are connected in sequence. The feed port of the hopper (1) is used to input biomass raw materials. The discharge port of the hopper (1) is connected to the feed end of the belt conveyor (2). The discharge end of the belt conveyor (2) is connected to the feed end of the vibrating screen (3). The discharge end of the vibrating screen (3) is connected to the feed end of the drying furnace (4). The discharge end of the drying furnace (4) is connected to the feed end of the metal chain plate conveyor (5). The discharge end of the metal chain plate conveyor (5) is connected to the inlet of the crusher (6). The outlet of the crusher (6) is connected to the silo (7).

3. A water-coal slurry gasification system using biomass as raw material according to claim 2, characterized in that: The powder making unit comprises a feeder (8), an anaerobic pyrolysis furnace (9), a carbon powder separator (10) and a carbon powder bin (11) which are connected in sequence, wherein the feed end of the feeder inputs the biomass crushed material in the biomass pretreatment unit bin (7), the discharge end of the feeder is connected to the feed port of the anaerobic pyrolysis furnace (9), the discharge port of the anaerobic pyrolysis furnace (9) is connected to the inlet of the carbon powder separator (10), and the outlet of the carbon powder separator (10) is connected to the carbon powder bin (11).

4. A water-coal slurry gasification system using biomass as raw material according to claim 3, characterized in that: The pulping unit comprises a pulping reaction device (12), a multi-stage elution separation device (13) and a water-coal slurry storage tank (14) which are connected in sequence; the feed end of the pulping reaction device (12) inputs the carbon powder in the carbon powder bin (11) of the powder making unit; the discharge end of the pulping reaction device (12) is connected to the inlet of the multi-stage elution separation device (13); the water-coal slurry outlet of the multi-stage elution separation device (13) is connected to the feed inlet of the water-coal slurry storage tank (14).

5. A water-coal slurry gasification system using biomass as raw material according to claim 4, characterized in that: The pulping unit further comprises a washing liquid purifying device (15), and the washing liquid outlet of the multi-stage elution separation device (13) is connected to the inlet of the washing liquid purifying device (15).

6. The water-coal slurry gasification system using biomass as raw material according to claim 3, characterized in that: The gasification unit comprises a coal slurry pump (16), a preheater (17), a gasifier (18), a radiation waste boiler (19) and a convection waste boiler (20) which are connected in sequence. The feed end of the coal slurry pump (16) inputs the water-coal slurry in the water-coal slurry storage tank (14) of the slurry making unit. The discharge end of the coal slurry pump (16) is connected to the feed end of the preheater (17). The discharge end of the preheater (17) is connected to the burner of the gasifier (18). The outlet of the synthesis gas of the gasifier (18) is connected to the inlet of the radiation waste boiler (19). The outlet of the synthesis gas of the radiation waste boiler (19) is connected to the inlet of the convection waste boiler (20).

7. A water-coal slurry gasification system using biomass as raw material according to claim 6, characterized in that: The gasification unit further comprises a slag lock hopper (21), and the gasification molten slag discharge end of the radiation waste boiler (19) is connected to the slag lock hopper (21).

8. The water-coal slurry gasification system using biomass as raw material according to claim 5, characterized in that: The synthesis gas processing unit comprises a dry dust removal device (22), a water scrubber (23), a cooling and dehydration device (24) and a desulfurization tower (25) which are connected in sequence, the air inlet of the dry dust removal device (22) is connected to the synthesis gas outlet of the convection waste boiler (20) of the gasification unit, the air outlet of the dry dust removal device (22) is connected to the air inlet of the water scrubber (23), the air outlet of the water scrubber (23) is connected to the air inlet of the cooling and dehydration device (24), and the air outlet of the cooling and dehydration device (24) is connected to the air inlet of the desulfurization tower (25).

9. A method of a water-coal slurry gasification system using biomass as raw material as claimed in claim 1, characterized in that: It includes the following steps: Step 1: Bulk biomass raw materials are used to enter the biomass pretreatment unit. The bulk biomass in the hopper (1) falls into the feeding end of the belt conveyor (2) from the discharge port of the hopper (1) by gravity, and is transported to the vibrating screen (3) through the belt conveyor (2). The bulk biomass vibrates at a high frequency in the vibrating screen (3), and dirt, bricks and other debris are separated from the biomass. The separated debris is removed, and the biomass after being de-impurized is sent to a drying furnace (4) at 120 to 150° C. for drying. The drying heat source is saturated steam produced by recovering the waste heat of the crude synthesis gas from the gasification unit. The dried biomass is sent to a crusher (6) through a metal chain conveyor (5) for crushing. The crushed biomass is crushed to obtain biomass crushed materials with a size of less than or equal to 10 cm, and the crushed materials are sent to a crushing bin (7); Step 2: The crushed material from the crushing bin (7) of the biomass pretreatment unit enters the milling unit, and the crushed biomass in the crushing bin (7) is fed into the anaerobic pyrolysis furnace (9) through a feeder. The anaerobic pyrolysis temperature is controlled at 270° C. to 300° C. The heat source is saturated steam produced by recovering the waste heat of the crude synthesis gas from the gasification unit. The crushed material is pyrolyzed in the anaerobic pyrolysis furnace (9) to obtain a solid particle product mainly composed of coke. The solid particle pyrolysis product is transported to the carbon powder separator (10) by pneumatic conveying to separate the carbon powder, and the separated biomass carbon powder is sent to the carbon powder bin (11); Step 3: the carbon powder material from the carbon powder bin (11) of the pulverizing unit enters the pulping unit, the biomass carbon powder in the carbon powder bin (11) is stirred and mixed with water in the pulping reaction device (12), the water used in the stirring and mixing process of the carbon powder and water is deionized water, a naphthalenesulfonic acid formaldehyde condensate dispersant is added to form a water-coal slurry, the water-coal slurry is sent to a multi-stage elution separation device (13), the water-coal slurry is subjected to a multi-stage dechlorination separation treatment with water to obtain a water wash and a water-coal slurry, the water wash is sent to a water wash purification device (15), and the water-coal slurry is sent to a water-coal slurry storage tank (14); Step 4: The water-coal slurry from the water-coal slurry storage tank (14) of the pulping unit enters the gasification unit, and is pressurized to 5 MPa by the coal slurry pump (16) and sent to the preheater (17) pipeline. The water-coal slurry in the pipeline is heated to 120° C. in the preheater (17). The heat source of the preheater (17) is saturated steam produced by recovering the waste heat of the crude synthesis gas of the gasification unit. The heated water-coal slurry is sent to the burner of the gasifier (18). The burner of the gasifier (18) adopts a multi-nozzle opposed arrangement. The gasifying agent used is pure oxygen with a pressure of 5 MPa and a temperature of 25° C., which is oxygen prepared by an electrolytic water device. The gasification pressure in the gasifier (18) is 4.5 MPa, and the gasification temperature is 1300° C. The water-coal slurry and the gasifying agent undergo a partial oxidation reaction in the gasifier (18). The high-temperature crude synthesis gas produced by the gasifier (18) carries the molten slag and ash into the gasifier (18). The high-temperature sensible heat is recovered in the radiation waste boiler (19) at the lower part, the temperature of the crude synthesis gas is reduced from 1300°C to 600°C, and 8.1Mpa saturated steam is produced as a by-product. At the same time, the circulating synthesis gas of the synthesis gas treatment unit is sprayed into the inlet of the radiation waste boiler (19) to quench it. The crude synthesis gas at the synthesis gas outlet of the radiation waste boiler (19) carries a small amount of solid fly ash into the convection waste boiler (20), and further heat recovery is carried out. The temperature of the crude synthesis gas is reduced to 300°C, and 5Mpa saturated steam is produced as a by-product. Most of the ash and slag entrained in the crude synthesis gas of the radiation waste boiler (19) enters the slag lock hopper (21) at the bottom of the radiation waste boiler (19) from the gasification molten slag outlet of the radiation waste boiler (19) under the action of gravity sedimentation and is discharged. The radiation waste boiler (19) and the convection waste boiler (20) together constitute a waste heat boiler. Part of the steam generated by the waste heat boiler is used for the system itself, and the rest is supplied to the outside. Step 5: The crude synthesis gas from the convection waste boiler (20) of the gasification unit enters the synthesis gas treatment unit, and the remaining solid particles and chlorine in the crude synthesis gas are removed by a dry dust removal device (22) and a water scrubber (23). The crude synthesis gas containing saturated water after washing leaves the top of the water scrubber (23) and is divided into two parts. One part is sent to the cooling and dehydration device (24) as product gas, and after cooling and dehydration in the cooling and dehydration device (24) and desulfurization in the desulfurization tower (25), a clean synthesis gas is obtained. The other part of the synthesis gas after dechlorination is sent to the radiation waste boiler (19) of the gasification unit as quenching gas.

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