Method for co-producing biomass gas and biomass charcoal

Abstract

The invention relates to the technical field of renewable energy sources, and discloses a method for co-producing biomass gas and biomass charcoal, which comprises the following steps: pretreating raw materials, selecting biomass raw materials, crushing, screening and drying, controlling the particle size of the biomass raw materials to be 5-30mm and the moisture content to be 10%-20%, and performing gasification reaction, adding the pretreated biomass raw material into a downdraft fixed bed gasification furnace, carrying out gasification reaction under the action of a gasification agent, controlling the temperature in the gasification furnace to be 800-1100 DEG C, the pressure to be 0.5 MPa from normal pressure, and the reaction time to be 1-3 hours, so as to generate crude biomass gas and biomass charcoal, and a water jacket circulating cooling system is used for maintaining the stability of the furnace body, so that the gasification reaction is fully and uniformly carried out in each reaction layer, and the yield and the calorific value stability of the biomass gas are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of renewable energy, in particular to a method for co-production of biomass gas and biomass charcoal. BACKGROUND

[0002] Biomass energy is the energy provided by living plants in nature, which stores solar energy through biomass as a medium. It is a renewable energy, and biomass gas is a kind of combustible energy converted from crop straw, forest waste, edible fungus residue, poultry manure and all kinds of combustible materials.

[0003] At present, due to the variety and complexity of biomass raw materials, the temperature field distribution in the gasification furnace is prone to unevenness during the gasification reaction. When the local temperature of the reaction area is too high or too low, the gasification reaction will be insufficient, which not only reduces the yield and calorific value of the biomass gas, but also affects the fixed carbon content and quality stability of the biomass charcoal. At the same time, the selection and injection ratio control of the gasification agent often depend on experience, and cannot be dynamically optimized and adjusted in real time according to the characteristics of the raw materials and the reaction state, which will destroy the reaction balance between the oxidation layer and the reduction layer, cause the tar content in the gas to be too high and the proportion of combustible components to be poor, increase the difficulty and cost of subsequent gas purification, and in the collection link of biomass charcoal, the cooling treatment efficiency of the high-temperature biomass charcoal discharged from the furnace is low in the traditional way, and there is a lack of online monitoring and grading means for the particle size and properties of the charcoal products, which easily leads to poor consistency of the final products and limited application value, and it is difficult to meet the specific requirements of biomass charcoal quality in different fields.

[0004] Therefore, the present application provides a method for co-production of biomass gas and biomass charcoal to solve the above problems. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a method for co-production of biomass gas and biomass charcoal, which solves the problems of reducing the yield and calorific value of biomass gas and affecting the fixed carbon content and quality stability of biomass charcoal as proposed in the background art.

[0006] To achieve the above object, the present application provides the following technical solution: a method for co-production of biomass gas and biomass charcoal, comprising the following steps: Step 1: raw material pretreatment, select biomass raw materials, crush, screen and dry, control the particle size of biomass raw materials to be 5-30mm, and the moisture content to be 10%-20%; Step two: gasification reaction, the pretreated biomass material is added into the downdraft fixed bed gasifier, and the gasification reaction is carried out under the action of the gasification agent, the gasification reaction includes a drying layer, a pyrolysis layer, an oxidation layer and a reduction layer, the temperature in the gasifier is controlled to be 800-1100℃, the pressure is controlled to be normal pressure to 0.5MPa, and the reaction time is controlled to be 1-3 hours, so that the crude biomass fuel gas and the biomass charcoal are generated; Step three: fuel gas purification, the crude biomass fuel gas is sequentially purified by a gravity dust collector and a cyclone dust collector, dust and tar are removed, and the purified biomass fuel gas is obtained, the heat value of the biomass fuel gas is 1100-1300Kcal / Nm 3 , and the components include 15%-25% of carbon monoxide, 10%-15% of hydrogen, 2%-5% of methane, 8%-12% of carbon dioxide, 50%-55% of nitrogen and a small amount of oxygen; Step four: charcoal collection and treatment, the biomass charcoal generated at the bottom of the gasifier is discharged through a spiral conveyor, and is subjected to cooling, screening and packaging, so that the biomass charcoal product is obtained, the fixed carbon content of the biomass charcoal is 60%-80%, and the ash content is 5%-15%; Step five: product storage and utilization, the purified biomass fuel gas is stored in a gas storage tank, and the biomass charcoal is stored in a sealed container.

[0007] Preferably, the gasification agent is one or more of air, oxygen or water vapor, the injection amount of the gasification agent is 0.5-1.5 times the weight of the biomass material, in the step two, the hearth diameter of the gasifier is 2.0-4.0m, the cross-sectional area is 3.14-12.56m 2 , the consumption of the biomass material is 1000-5000kg / h, the yield of the biomass fuel gas is 2000-10000Nm 3 / h, and the yield of the biomass charcoal is 200-1000kg / h.

[0008] Preferably, in the step one, the biomass material is selected from at least one of wood chips, straw, fruit shells, bamboo materials or agricultural wastes, the crushing treatment adopts a hammer crusher, the particle size after crushing is 5-30mm, the drying treatment adopts a roller dryer or an air flow dryer, the drying temperature is 80-120℃, and the drying time is 0.5-2 hours, so that the moisture content is reduced to 10%-20%.

[0009] Preferably, the wood chips are one of birch, pine or rubber wood, and the industrial analysis parameters are as follows: the moisture content is less than 10%, the volatile matter content is 75%-85%, the ash content is less than 2%, and the fixed carbon content is 15%-20%; The straw is one of corn straw, wheat straw or cotton straw, and its industrial analysis parameters are: moisture content less than 15%, volatile content 70%-80%, ash content less than 5%, and fixed carbon content 15%-20%.

[0010] Preferably, in the second step, the gasification furnace is a down-draft fixed-bed gasification furnace, which comprises a furnace cover, a water jacket, a furnace grate and a transmission system, the water jacket is connected with a circulating water tank to form a natural circulation cooling system, the temperature of the furnace body is controlled to be not more than 300 DEG C, the furnace grate is made of stainless steel and can be rotated to uniformly distribute air and discharge the biomass charcoal, and the transmission system is driven by a motor reducer with a power of 10-30 kW.

[0011] Preferably, the specific process of the gasification reaction is as follows: Drying layer: temperature 200-300 DEG C, biomass raw materials exchange heat with hot gas, and water is evaporated; Pyrolysis layer: temperature 500-600 DEG C, biomass generates pyrolysis reaction to generate charcoal, volatile and tar; Oxidation layer: temperature 900-1100 DEG C, charcoal generates oxidation reaction with gasification agent to generate carbon dioxide and release heat; Reduction layer: temperature 600-800 DEG C, carbon dioxide generates reduction reaction with water vapor to generate carbon monoxide and hydrogen; Among them, the oxygen concentration of the oxidation layer is 15%-21%, and the water vapor injection amount of the reduction layer is 0.1-0.5 times the weight of the biomass raw materials.

[0012] Preferably, in the third step, the working principle of the gravity dust collector is to use the gravity of dust itself to settle, and the dust removal efficiency is 60%-80%, the working principle of the cyclone dust collector is to use centrifugal force to remove dust, and the dust removal efficiency is 80%-90%, and the dust content in the purified biomass fuel gas is less than 50 mg / Nm 3 , and the tar content is less than 100 mg / Nm 3 .

[0013] Preferably, in the fourth step, the biomass charcoal is cooled by indirect water cooling or air cooling to room temperature, and the screening is carried out by a vibrating screen with a mesh size of 1-10 mm, and the biomass charcoal is divided into fine charcoal, medium charcoal and coarse charcoal, and the packaging is carried out by using moisture-proof sealed bags with a weight of 10-50 kg per bag.

[0014] Preferably, the method further comprises a sixth step of heat recovery, wherein the waste heat generated in the gasification reaction process is recovered through a heat exchanger, and the heat exchanger is a tube-shell or plate heat exchanger, and the heat recovery efficiency is 60%-80%.

[0015] Preferably, the method further comprises a seventh step: process monitoring and automatic control, real-time monitoring of the gasifier temperature, pressure, fuel gas composition and carbon yield by sensors, including thermocouples, pressure transmitters and gas analyzers, and automatically adjusting the gasification agent injection amount, grate rotation speed and dust collector operating parameters by a PLC system with over-limit alarm and interlock control functions.

[0016] Compared with the prior art, the present application provides a method for co-production of biomass fuel gas and biomass charcoal, which has the following beneficial effects: 1. In the present application, by accurately controlling the temperature field distribution in the gasifier, setting the specific temperature range of the drying layer, pyrolysis layer, oxidation layer and reduction layer, and maintaining the stability of the furnace body by using a water jacket circulating cooling system, the local temperature in the gasifier can be avoided to be too high or too low, and the gasification reaction can be fully and uniformly carried out in each reaction layer, thereby improving the yield and heat value stability of the biomass fuel gas, and ensuring the consistency of the fixed carbon content and quality of the biomass charcoal product, solving the problems of insufficient reaction and unstable product quality caused by uneven temperature field distribution.

[0017] 2. In the present application, by accurately setting the type, mixing ratio and injection amount of the gasification agent, and adjusting the oxygen concentration and water vapor injection amount according to the different reaction requirements of the oxidation layer and the reduction layer, and combining with the real-time monitoring and feedback adjustment of the automatic control system, the gasification agent ratio can be dynamically optimized according to the characteristics of the raw material and the reaction state, the efficient balance of the oxidation reaction and the reduction reaction can be ensured, thereby improving the proportion of combustible components in the biomass fuel gas, reducing the tar content, reducing the subsequent purification load, and solving the problems of poor gas quality and high tar content caused by the dependence of gasification agent control on experience and the destruction of reaction balance.

[0018] 3. In the present application, in the production and processing of biomass charcoal, high-temperature biomass charcoal is discharged by using a screw conveyor, and immediately cooled and standardized screened and classified, the biomass charcoal is divided into different types of fine charcoal, medium charcoal and coarse charcoal according to the accurate particle size, and the consistency of the processing process is ensured by combining with the automatic monitoring means, so that the fine and commercial processing of the biomass charcoal product can be realized, not only the cooling efficiency and operation safety are improved, but also the final output of the biomass charcoal has clear classification standards and stable quality, improving its application value and market competitiveness as a soil conditioner, adsorbent and fuel, and the method integrates a heat recovery system and full-process automatic control, improving the overall energy efficiency and production stability, solving the problems of insufficient subsequent processing of biomass charcoal and low product value. DETAILED DESCRIPTION

[0019] With reference to the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0020] Embodiment 1: The method for co-producing biomass gas and biomass charcoal comprises the following steps: Step one: raw material pretreatment, selecting biomass raw material, crushing, screening and drying treatment, controlling the particle size of the biomass raw material to be 5 mm and the moisture content to be 10%; Step two: gasification reaction, adding the pretreated biomass raw material into a down-draft fixed bed gasifier, and performing gasification reaction under the action of a gasification agent, the gasification reaction including a drying layer, a pyrolysis layer, an oxidation layer and a reduction layer, controlling the temperature in the gasifier to be 800 DEG C, the pressure to be normal pressure to 0.5 MPa, and the reaction time to be 1 hour, to generate crude biomass gas and biomass charcoal; Step three: gas purification, sequentially passing the crude biomass gas through a gravity dust collector and a cyclone dust collector for purification treatment to remove dust and tar, to obtain purified biomass gas, the heat value of the biomass gas being 1100 Kcal / Nm 3 , the components including carbon monoxide 15%, hydrogen 10%, methane 2%, carbon dioxide 8%, nitrogen 50% and trace oxygen; Step four: charcoal collection and treatment, discharging the biomass charcoal generated at the bottom of the gasifier through a screw conveyor, and performing cooling, screening and packaging to obtain biomass charcoal products, the fixed carbon content of the biomass charcoal being 60% and the ash content being 5%; Step five: product storage and utilization, storing the purified biomass gas in a gas storage tank and storing the biomass charcoal in a sealed container; The gasification agent is one or a mixture of more than one of air, oxygen or water vapor, the injection amount of the gasification agent being 0.5 times the weight of the biomass raw material, in step two, the hearth diameter of the gasifier is 2.0 m, the cross-sectional area is 3.14 m 2 , the consumption of the biomass raw material is 1000 kg / h, the biomass gas production is 2000 Nm 3 / h, and the biomass charcoal production is 200 kg / h; In step one, the biomass raw material is selected from at least one of wood chips, straw, fruit shells, bamboo materials or agricultural waste, the crushing treatment adopts a hammer crusher, the particle size after crushing is 5 mm, the drying treatment adopts a drum dryer or an air flow dryer, the drying temperature is 80 DEG C, the drying time is 0.5 hours, and the moisture content is reduced to 10%; The wood chip is one of birch, pine or rubber wood, and its industrial analysis parameters are: moisture content less than 10%, volatile content 75%, ash content less than 2%, and fixed carbon content 15%; The straw is one of corn straw, wheat straw or cotton straw, and its industrial analysis parameters are: moisture content less than 15%, volatile content 70%, ash content less than 5%, and fixed carbon content 15%; In step two, the gasifier is a down-draft fixed bed gasifier, which includes a furnace cover, a water jacket, a furnace grate and a transmission system. The water jacket is connected with a circulating water tank to form a natural circulation cooling system, so that the temperature of the furnace body is controlled to be not more than 300℃. The furnace grate is made of stainless steel and can rotate to uniformly distribute the wind and discharge the biomass charcoal. The transmission system is driven by a motor reducer, and the power is 10kW; The specific process of the gasification reaction is as follows: Dry layer: temperature 200℃, biomass raw material exchanges heat with hot gas, and water evaporates; Pyrolysis layer: temperature 500℃, biomass undergoes pyrolysis reaction to generate charcoal, volatile matter and tar; Oxidation layer: temperature 900℃, charcoal undergoes oxidation reaction with gasifying agent to generate carbon dioxide and release heat; Reduction layer: temperature 600℃, carbon dioxide undergoes reduction reaction with water vapor to generate carbon monoxide and hydrogen; Among them, the oxygen concentration of the oxidation layer is 15%, and the water vapor injection amount of the reduction layer is 0.1 times the weight of the biomass raw material; In step three, the working principle of the gravity dust collector is to use the gravity settlement of dust itself, and the dust removal efficiency is 60%. The working principle of the cyclone dust collector is to use centrifugal force to remove dust, and the dust removal efficiency is 80%. The dust content in the purified biomass fuel gas is less than 50mg / Nm 3 , and the tar content is less than 100mg / Nm 3 ; In step four, the cooling of the biomass charcoal adopts indirect water cooling or air cooling method, and is cooled to room temperature. The screening adopts a vibrating screen with a screen aperture of 1mm, and the biomass charcoal is divided into fine charcoal, medium charcoal and coarse charcoal. The packaging adopts a moisture-proof sealed bag, and the weight of each bag is 10kg; The method further includes step six: heat recovery, the waste heat generated in the gasification reaction process is recovered through a heat exchanger, and the heat exchanger is a tube-shell or plate heat exchanger, and the heat recovery efficiency is 60%; The method further includes step seven: process monitoring and automatic control, the temperature, pressure, gas composition and charcoal yield of the gasifier are monitored in real time through sensors, and the gasifying agent injection amount, furnace grate rotating speed and dust collector operating parameters are automatically adjusted through a PLC system. The sensors include thermocouples, pressure transmitters and gas analyzers, and the PLC system has an over-limit alarm and interlocking control function.

[0021] Embodiment 2: The method for co-production of biomass gas and biomass char comprises the following steps: Step one: raw material pretreatment, selecting biomass raw material, crushing, screening and drying treatment, controlling the particle size of the biomass raw material to be 20 mm and the moisture content to be 15%; Step two: gasification reaction, adding the pretreated biomass raw material into a downdraft fixed bed gasifier, and performing gasification reaction under the action of a gasification agent, the gasification reaction including a drying layer, a pyrolysis layer, an oxidation layer and a reduction layer, controlling the temperature in the gasifier to be 900℃, the pressure to be normal pressure to 0.5 MPa, and the reaction time to be 2 hours, to generate crude biomass gas and biomass char; Step three: gas purification, sequentially passing the crude biomass gas through a gravity dust collector and a cyclone dust collector for purification treatment to remove dust and tar, to obtain purified biomass gas, the heat value of the biomass gas being 1200 Kcal / Nm 3 , the components including carbon monoxide 20%, hydrogen 13%, methane 3%, carbon dioxide 10%, nitrogen 52% and trace oxygen; Step four: collection and treatment of char, discharging the biomass char generated at the bottom of the gasifier through a screw conveyor, and performing cooling, screening and packaging to obtain biomass char products, the fixed carbon content of the biomass char being 70% and the ash content being 10%; Step five: product storage and utilization, storing the purified biomass gas in a gas storage tank and storing the biomass char in a sealed container; The gasification agent is one or a mixture of more than one of air, oxygen or water vapor, the injection amount of the gasification agent being 1.0 times the weight of the biomass raw material, in step two, the hearth diameter of the gasifier being 3.0 m, the cross-sectional area being 6.56 m 2 , the consumption of the biomass raw material being 3000 kg / h, the biomass gas yield being 6000 Nm 3 / h, and the biomass char yield being 600 kg / h; In step one, the biomass raw material is selected from at least one of wood chips, straw, fruit shells, bamboo or agricultural waste, the crushing treatment adopts a hammer crusher, the particle size after crushing is 20 mm, the drying treatment adopts a drum dryer or an air flow dryer, the drying temperature is 100℃, and the drying time is 1 hour, so as to reduce the moisture content to 15%; The wood chips are one of birch, pine or rubber wood, and the industrial analysis parameters thereof are: moisture content less than 10%, volatile matter content 80%, ash content less than 2%, and fixed carbon content 17%; The straw is one of corn straw, wheat straw or cotton straw, and the industrial analysis parameters thereof are: moisture content less than 15%, volatile matter content 75%, ash content less than 5%, and fixed carbon content 17%; In step two, the gasifier is a down-draft fixed-bed gasifier, which includes a furnace cover, a water jacket, a furnace grate, and a transmission system. The water jacket is connected with a circulating water tank to form a natural circulation cooling system, which controls the furnace body temperature to be no more than 300℃. The furnace grate is made of stainless steel and can rotate to uniformly distribute the wind and discharge the biomass charcoal. The transmission system is driven by a motor reducer with a power of 20kW; The specific process of the gasification reaction is as follows: Dry layer: temperature 250℃, biomass raw materials exchange heat with hot gas, and water evaporates; Pyrolysis layer: temperature 550℃, biomass undergoes pyrolysis reaction to generate charcoal, volatile matter, and tar; Oxidation layer: temperature 1000℃, charcoal undergoes oxidation reaction with gasifying agent to generate carbon dioxide and release heat; Reduction layer: temperature 700℃, carbon dioxide undergoes reduction reaction with water vapor to generate carbon monoxide and hydrogen; Among them, the oxygen concentration of the oxidation layer is 18%, and the water vapor injection amount of the reduction layer is 0.3 times the weight of the biomass raw materials; In step three, the working principle of the gravity dust collector is to use the gravity of dust itself to settle down, and the dust removal efficiency is 70%. The working principle of the cyclone dust collector is to use centrifugal force to remove dust, and the dust removal efficiency is 85%. The dust content in the purified biomass fuel gas is less than 50mg / Nm 3 , and the tar content is less than 100mg / Nm 3 ; In step four, the biomass charcoal is cooled by indirect water cooling or air cooling to room temperature. The screening uses a vibrating screen with a mesh size of 5mm to divide the biomass charcoal into fine charcoal, medium charcoal, and coarse charcoal. The packaging uses moisture-proof sealed bags, and each bag weighs 30kg; The method further includes step six: heat recovery, which recovers the waste heat generated during the gasification reaction process through a heat exchanger. The heat exchanger is a tube-shell or plate heat exchanger, and the heat recovery efficiency is 70%; The method further includes step seven: process monitoring and automatic control, which uses sensors to monitor the gasifier temperature, pressure, fuel gas composition, and charcoal yield in real time, and uses a PLC system to automatically adjust the gasifying agent injection amount, furnace grate speed, and dust collector operating parameters. The sensors include thermocouples, pressure transmitters, and gas analyzers. The PLC system has an over-limit alarm and interlocking control function.

[0022] Example 3: The method for co-producing biomass fuel gas and biomass charcoal includes the following steps: Step one: raw material pretreatment, select biomass raw materials, crush, screen, and dry to control the particle size of the biomass raw materials to be 30mm and the water content to be 20%; Step two: gasification reaction, the pretreated biomass raw material is added into the downdraft fixed bed gasifier, and the gasification reaction is carried out under the action of the gasification agent, the gasification reaction includes a drying layer, a pyrolysis layer, an oxidation layer and a reduction layer, the temperature in the gasifier is controlled to be 1100 DEG C, the pressure is normal pressure to 0.5 MPa, the reaction time is 3 hours, and the crude biomass fuel gas and the biomass charcoal are generated; Step three: fuel gas purification, the crude biomass fuel gas is sequentially purified by a gravity dust collector and a cyclone dust collector, dust and tar are removed, and the purified biomass fuel gas is obtained, the heat value of the biomass fuel gas is 1300 Kcal / Nm 3 , and the components include 25% of carbon monoxide, 15% of hydrogen, 5% of methane, 12% of carbon dioxide, 55% of nitrogen and a small amount of oxygen; Step four: charcoal collection and treatment, the biomass charcoal generated at the bottom of the gasifier is discharged through a spiral conveyor, and is cooled, screened and packaged to obtain a biomass charcoal product, the fixed carbon content of the biomass charcoal is 80%, and the ash content is 15%; Step five: product storage and utilization, the purified biomass fuel gas is stored in a gas storage tank, and the biomass charcoal is stored in a sealed container; The gasification agent is one or more of air, oxygen or steam, the injection amount of the gasification agent is 1.5 times the weight of the biomass raw material, in step two, the hearth diameter of the gasifier is 4.0 m, the cross-sectional area is 12.56 m 2 , the consumption of the biomass raw material is 5000 kg / h, the biomass fuel gas production is 10000 Nm 3 / h, and the biomass charcoal production is 1000 kg / h; In step one, the biomass raw material is selected from at least one of wood chips, straw, fruit shells, bamboo materials or agricultural waste, the crushing treatment adopts a hammer crusher, the particle size after crushing is 30 mm, the drying treatment adopts a roller dryer or an air flow dryer, the drying temperature is 120 DEG C, and the drying time is 2 hours, so that the moisture content is reduced to 20%; The wood chips are one of birch, pine or rubber wood, and the industrial analysis parameters are that the moisture content is less than 10%, the volatile matter content is 85%, the ash content is less than 2%, and the fixed carbon content is 20%; The straw is one of corn straw, wheat straw or cotton straw, and the industrial analysis parameters are that the moisture content is less than 15%, the volatile matter content is 80%, the ash content is less than 5%, and the fixed carbon content is 20%; In step two, the gasifier is a downdraft fixed bed gasifier, which includes a furnace cover, a water jacket, a grate and a transmission system, the water jacket is connected with a circulating water tank to form a natural circulation cooling system, the temperature of the furnace body is controlled to be not more than 300 DEG C, the grate is made of stainless steel and can be rotated to uniformly distribute the wind and discharge the biomass charcoal, and the transmission system is driven by a motor reducer, and the power is 30 kW; The specific process of the gasification reaction is as follows: Drying layer: temperature 300℃, biomass raw material exchanges heat with hot gas, and moisture evaporates; Pyrolysis layer: temperature 600℃, biomass undergoes pyrolysis reaction to generate char, volatile matter and tar; Oxidation layer: temperature 1100℃, char undergoes oxidation reaction with gasification agent to generate carbon dioxide and release heat; Reduction layer: temperature 800℃, carbon dioxide undergoes reduction reaction with water vapor to generate carbon monoxide and hydrogen; Among them, the oxygen concentration of the oxidation layer is 21%, and the water vapor injection amount of the reduction layer is 0.5 times the weight of the biomass raw material; In step three, the working principle of the gravity dust collector is to use the gravity of the dust itself to settle, and the dust removal efficiency is 80%, and the working principle of the cyclone dust collector is to use the centrifugal force to remove dust, and the dust removal efficiency is 90%, and the dust content in the purified biomass fuel gas is less than 50mg / Nm 3 , and the tar content is less than 100mg / Nm 3 ; In step four, the biomass char is cooled by indirect water cooling or air cooling, cooled to room temperature, and screened by a vibrating screen with a screen aperture of 10mm, and the biomass char is divided into fine char, medium char and coarse char, and packaged in moisture-proof sealed bags, each bag weighing 50kg; The method further comprises step six: heat recovery, the waste heat generated in the gasification reaction process is recovered through a heat exchanger, the heat exchanger is a tube-shell or plate heat exchanger, and the heat recovery efficiency is 80%; The method further comprises step seven: process monitoring and automatic control, the temperature, pressure, fuel gas composition and char yield of the gasification furnace are monitored in real time through sensors, and the gasification agent injection amount, grate rotation speed and dust collector operating parameters are automatically adjusted through a PLC system, the sensors include thermocouples, pressure transmitters and gas analyzers, and the PLC system has an over-limit alarm and interlocking control function.

[0023] Comparative Example 1, the difference between this comparative example and Example 1 is that the temperature of each reaction layer in the gasification furnace is not accurately controlled in the gasification reaction process.

[0024] Comparative Example 2, the difference between this comparative example and Example 2 is that the injection amount and ratio of the gasification agent are not dynamically adjusted in real time by an automatic control system, but a fixed gasification agent flow is used.

[0025] Comparative Example 3, the difference between this comparative example and Example 3 is that the biomass char is not subjected to fine cooling and screening classification after being produced.

[0026] Comparative Example 4, which differs from Example 3 in that the heat recovery system was not integrated.

[0027] The methods of coproduction of biomass gas and biochar in Examples 1-3 and Comparative Examples 1-4 were tested for performance, with the test items and test methods as follows: Gas heat value test: a gas calorimeter was used to determine the low heat value of the biomass gas; Gas component analysis: a gas chromatograph was used to determine the volume percentage of carbon monoxide, hydrogen, methane, carbon dioxide, nitrogen and oxygen in the biomass gas; Tar content test: a gravimetric method or ultraviolet fluorescence method was used to determine the tar content; Biomass char industrial analysis: the moisture content, ash content, volatile matter content and fixed carbon content of the biomass char were determined; Energy efficiency calculation: the ratio of the sum of the heat values of the biomass gas and the biomass char output by the system to the heat value of the input biomass raw material was calculated.

[0028] The test key data of the biomass gas and biomass char prepared in Examples 1-3 and Comparative Examples 1-4 are recorded in the following table:

[0029] By comparing and analyzing the data in the table, it can be seen that the biomass gas and biomass charcoal co-produced by the processes in Examples 1-3 have significantly better performance than the products prepared by the processes in Comparative Examples 1-4, which shows that by accurately controlling the temperature field distribution in the gasifier, setting specific temperature intervals for the drying layer, pyrolysis layer, oxidation layer and reduction layer, and using the water jacket circulating cooling system to maintain the stability of the furnace body, the problem of local temperature being too high or too low in the gasifier can be avoided, the gasification reaction can be ensured to proceed fully and uniformly in each reaction layer, thereby improving the yield and heat value stability of the biomass gas, and ensuring the consistency of the fixed carbon content and quality of the biomass charcoal product, solving the problems of insufficient reaction and unstable product quality caused by uneven temperature field distribution. By accurately setting the types, mixing ratios and injection amounts of the gasification agents, and adjusting the oxygen concentration and water vapor injection amount according to the different reaction requirements of the oxidation layer and the reduction layer, and combining real-time monitoring and feedback adjustment of the automatic control system, the gasification agent ratio can be dynamically optimized according to the characteristics of the raw materials and the reaction state, ensuring the efficient balance of the oxidation reaction and the reduction reaction, thereby increasing the proportion of combustible components in the biomass gas, reducing the tar content, reducing the subsequent purification load, solving the problems of poor gas quality and high tar content caused by the dependence on experience for gasification agent control and the destruction of reaction balance, and realizing the fine and commercial processing of the biomass charcoal product by using a screw conveyor to discharge the high-temperature biomass charcoal and immediately performing efficient cooling and standardized screening and grading, dividing the biomass charcoal into different types of fine charcoal, medium charcoal and coarse charcoal according to the accurate particle size, and combining automatic monitoring means to ensure the consistency of the processing process. Not only does this improve the cooling efficiency and operation safety, but also the final output of biomass charcoal has clear grading standards and stable quality, improving its application value and market competitiveness as a soil conditioner, adsorbent and fuel. At the same time, the method integrates a heat recovery system and full-process automatic control, improving the overall energy efficiency and production stability, and solving the problems of insufficient subsequent processing of biomass charcoal and low product value.

[0030] By comparing and analyzing the relevant data in the table, it can be seen that the biomass gas co-produced by the method of the present application has the advantages of high heat value and low tar content, the biomass charcoal has stable quality and high application value, and the overall energy efficiency of the system is excellent, which shows that the method for co-producing biomass gas and biomass charcoal provided by the present application has more excellent comprehensive performance.

[0031] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and implementations, it is to be understood that the terminology used is for the purpose of descriptive clarity and that it is intended to be limited only by the words recited in the appended claims. It is to be understood that the terms "including", "comprising", "consisting" and variations thereof do not preclude the addition of further integers to the claimed combination of integers. It is to be understood that the terms "including", "comprising", "consisting" and variations thereof encompass the various features of the embodiments described herein, and are not restricted to the use of only the most preferred embodiments. It is further to be understood that the use of relational terms such as first and second, and the like, do not denote a physical or logical order or relationship among the various elements, but are used simply for distinguishing between various elements for clarity. It is to be understood that the terms "comprising", "including", and "having" and variations thereof are intended to be equivalent and open-ended, and include the various embodiments of the present application as recited in the claims. It is to be understood that the terms "including", "comprising", "consisting" and variations thereof encompass the various features of the embodiments described herein, and are not restricted to the use of only the most preferred embodiments. It is further to be understood that the use of relational terms such as first and second, and the like, do not denote a physical or logical order or relationship among the various elements, but are used simply for distinguishing between various elements for clarity. It is to be understood that the terms "comprising", "including", and "having" and variations thereof are intended to be equivalent and open-ended, and include the various embodiments of the present application as recited in the claims.

[0032] While the embodiments of the application have been shown and described herein, it is understood that modifications, substitutions, changes, and alterations can be made by those skilled in the art without departing from the spirit of the present application, which is defined by the appended claims and their equivalents.

Claims

1. A method for co-producing biogas and biochar, characterized in that, Includes the following steps: Step 1: Raw material pretreatment. Select biomass raw materials, crush, screen and dry them, and control the particle size of the biomass raw materials to be 5-30mm and the moisture content to be 10%-20%. Step 2: Gasification reaction. The pretreated biomass feedstock is added to a downdraft fixed-bed gasifier and undergoes a gasification reaction under the action of a gasifying agent. The gasification reaction includes a drying layer, a pyrolysis layer, an oxidation layer, and a reduction layer. The temperature inside the gasifier is controlled at 800-1100℃, the pressure is atmospheric pressure to 0.5MPa, and the reaction time is 1-3 hours, producing crude biomass fuel gas and biochar. Step 3: Gas purification. The crude biomass gas is sequentially passed through a gravity dust collector and a cyclone dust collector for purification to remove dust and tar, resulting in purified biomass gas with a calorific value of 1100-1300 Kcal / Nm³. 3 The components include 15%-25% carbon monoxide, 10%-15% hydrogen, 2%-5% methane, 8%-12% carbon dioxide, 50%-55% nitrogen, and trace amounts of oxygen. Step 4: Collection and processing of charcoal. The biomass charcoal produced at the bottom of the gasifier is discharged through a screw conveyor, cooled, screened, and packaged to obtain the biomass charcoal product. The fixed carbon content of the biomass charcoal is 60%-80%, and the ash content is 5%-15%. Step 5: Product storage and utilization. The purified biomass gas is stored in a gas storage tank, and the biochar is stored in a sealed container.

2. The method for co-producing biogas and biochar according to claim 1, characterized in that, The gasifying agent is one or more of air, oxygen, or water vapor, and the injection amount of the gasifying agent is 0.5-1.5 times the weight of the biomass feedstock. In step two, the furnace diameter of the gasifier is 2.0-4.0m, and the cross-sectional area is 3.14-12.56m². 2 The biomass feedstock consumption is 1000-5000 kg / h, and the biomass gas production is 2000-10000 Nm³. 3 / h, biochar production is 200-1000 kg / h.

3. The method for co-producing biogas and biochar according to claim 1, characterized in that, In step one, the biomass raw material is selected from at least one of wood chips, straw, fruit shells, bamboo or agricultural waste. The crushing process is carried out using a hammer crusher, and the particle size after crushing is 5-30mm. The drying process is carried out using a drum dryer or an airflow dryer, with a drying temperature of 80-120℃ and a drying time of 0.5-2 hours, so that the moisture content is reduced to 10%-20%.

4. The method for co-producing biogas and biochar according to claim 1, characterized in that, The wood chips are one of birch, pine, or rubberwood, and their industrial analysis parameters are: moisture content less than 10%, volatile matter content 75%-85%, ash content less than 2%, and fixed carbon content 15%-20%. The straw is one of corn straw, wheat straw or cotton straw, and its industrial analysis parameters are: moisture content less than 15%, volatile matter content 70%-80%, ash content less than 5%, and fixed carbon content 15%-20%.

5. The method for co-producing biogas and biochar according to claim 1, characterized in that, In step two, the gasifier is a downdraft fixed-bed gasifier, including a furnace cover, a water jacket, a grate, and a transmission system. The water jacket is connected to a circulating water tank to form a natural circulation cooling system, controlling the furnace body temperature to not exceed 300°C. The grate is made of stainless steel and can rotate to evenly distribute air and discharge biochar. The transmission system is driven by a motor reducer with a power of 10-30kW.

6. The method for co-producing biogas and biochar according to claim 1, characterized in that, The specific process of the gasification reaction is as follows: Drying layer: Temperature 200-300℃, biomass raw materials exchange heat with hot gas, and moisture evaporates; Pyrolysis layer: Temperature 500-600℃, biomass undergoes pyrolysis reaction, producing char, volatile matter and tar; Oxidation layer: At a temperature of 900-1100℃, carbon reacts with the gasifying agent to produce carbon dioxide and release heat. Reduction layer: Temperature 600-800℃, carbon dioxide and water vapor undergo a reduction reaction to produce carbon monoxide and hydrogen; The oxygen concentration in the oxidation layer is 15%-21%, and the water vapor injection amount in the reduction layer is 0.1-0.5 times the weight of the biomass raw material.

7. The method for co-producing biogas and biochar according to claim 1, characterized in that, In step three, the gravity dust collector works by utilizing the gravity settling of dust, achieving a dust removal efficiency of 60%-80%. The cyclone dust collector works by using centrifugal force to remove dust, achieving a dust removal efficiency of 80%-90%. The dust content in the purified biomass gas is less than 50 mg / Nm³. 3 Tar content less than 100 mg / Nm 3 .

8. A method for co-producing biogas and biochar according to claim 1, characterized in that, In step four, the biochar is cooled by indirect water cooling or air cooling to room temperature. The sieving is done by a vibrating screen with a mesh size of 1-10mm, which separates the biochar into fine char, medium char and coarse char. The packaging is done in moisture-proof sealed bags, each weighing 10-50kg.

9. A method for co-producing biogas and biochar according to claim 1, characterized in that, The method further includes step six: heat recovery and utilization, in which the waste heat generated during the gasification reaction is recovered through a heat exchanger, wherein the heat exchanger is a shell-and-tube type or a plate heat exchanger, and the heat recovery efficiency is 60%-80%.

10. A method for co-producing biogas and biochar according to claim 1, characterized in that, The method also includes step seven: process monitoring and automated control, which involves real-time monitoring of gasifier temperature, pressure, gas composition and char output through sensors, and automatic adjustment of gasifying agent injection amount, grate speed and dust collector operating parameters through a PLC system. The sensors include thermocouples, pressure transmitters and gas analyzers, and the PLC system has over-limit alarm and interlock control functions.

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