Biomass and coal co-gasification papermaking energy supply system and method

Abstract

The invention provides a biomass and coal co-gasification papermaking energy supply system and method. The system is composed of a screening unit, a smashing unit, a primary gasification unit, a pyrolysis unit, a secondary gasification unit, a water gas conversion unit, an acidification unit, a carbonization unit, an alkalization unit, a fuel cell and the like. Low-quality wood and bark resin are screened out from papermaking raw materials to serve as biomass raw materials and smashed into biomass powder, part of the biomass powder and coal are co-gasified, part of the biomass powder is directly pyrolyzed, part of the biomass powder is combusted, and biomass ash is generated to serve as a gasification process catalyst; black liquor generated by the pulping and bleaching unit is converted into coarse carbon through the acidification and carbonization unit, part of the coarse carbon is converted into activated carbon through the alkalization and activation unit and serves as an adsorbent of the carbonization unit, part of the coarse carbon and coal are converted into CO through two-stage gasification and converted into hydrogen after water-gas conversion, and the hydrogen serves as a fuel cell raw material to generate electric energy; biomass is utilized in multiple modes, so that energy is fully utilized.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass energy utilization, and in particular relates to a papermaking energy supply system and method for co-gasification of biomass and coal. Background Art

[0002] As one of the eight major industries in the country, the papermaking industry is an important support for the national economy and involves all aspects of daily life. At the same time, the papermaking industry has greatly driven the development of other industries such as forestry, agriculture, printing, and machinery, playing an irreplaceable role. In order to meet the needs of the country and the market, the scale of the papermaking industry has continued to expand, and the industrial capacity has increased, and the energy required has also increased. Therefore, the total carbon emissions of the papermaking industry have basically remained at a high level in recent years, and have probably shown a trend of increasing year by year.

[0003] In this process, the energy and heat consumption required by enterprises gradually increase. In order to ensure the quality and performance of paper products, most enterprises generally use self-built power plants to generate electricity for their own consumption. Self-built power plants often use the traditional method of directly burning coal to generate electricity. Although the cost is low, due to the limited fossil energy, the thermal efficiency is not very high, and a large amount of greenhouse gases, sulfides, etc. are also produced. Considering aspects such as resource utilization and environmental impact, in the long run, the disadvantages outweigh the advantages.

[0004] In addition, paper mills will screen out a large amount of low-quality wood paper and bark resin during the raw material screening process. These low-quality raw materials are not suitable for making high-quality paper. They are often simply burned, resulting in a large amount of energy waste and carbon emissions. Further conversion of low-quality papermaking raw materials as biomass can achieve efficient recycling of waste products. For the pulping process, this process will produce a large amount of wastewater. The wastewater composition is complex, and most of it is black liquor. Black liquor contains a large amount of organic matter such as lignin and cellulose. If it is directly discharged into the water body without treatment, it will cause serious pollution. Up to now, the more mature and large-scale black liquor treatment method is combustion alkali recovery, which generally involves extraction, evaporation concentration, combustion, and causticization. First, the black liquor is separated and extracted from the wastewater, and after evaporation and concentration, it enters the recovery boiler for combustion, and the heat of its combustion can be provided to the paper mill. The organic sodium salt in the black liquor is burned to form molten sodium carbonate, and the supplemented mirabilite is reduced to sodium sulfide. After the melt is dissolved, green liquor containing a small amount of iron ions is obtained. The green liquor reacts with lime to generate sodium hydroxide, and the sodium hydroxide recovery efficiency can generally reach more than 90%. This method can recover heat energy, but it can only recover sodium hydroxide, which can be said to be relatively mature. However, this method can only allow the organic matter in the black liquor to be used for combustion, and it requires large-scale equipment such as multi-stage burners and evaporators. The initial investment cost is relatively large, so it is suitable for some medium and large-scale paper mills.

[0005] The traditional direct combustion of coal has low power supply efficiency, low energy utilization rate, and environmental pollution; papermaking waste is often simply burned, which wastes energy and causes a large amount of carbon emissions; the equipment cost required for the alkali recovery process is high, the black liquor treatment capacity is limited, and the resource utilization rate is insufficient. The present invention proposes a papermaking energy supply system and method for co-gasification of biomass and coal. Summary of the invention

[0006] In view of this, the present invention proposes a papermaking energy supply system and method for co-gasification of biomass and coal. The system can gasify biomass and coal for papermaking in a graded manner to produce heat. A part of the product is used to supply fuel cells for power generation, and the electric energy is used to drive the fan to rotate and accelerate drying; another part of the product provides raw materials for black liquor acidification treatment to increase the reaction rate; and the heat energy is recycled through a heat exchange device.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A papermaking energy supply system for co-gasification of biomass and coal, characterized in that it includes a screening unit, a crushing unit, a flow control unit, a primary gasification unit, a combustion unit, a pyrolysis unit, a secondary gasification unit, a water-gas shift unit, a heat transfer unit, an acidification unit, a carbonization unit, an alkalization unit, an activation unit, and a fuel cell, wherein:

[0009] The screening unit has at least one inlet for waste paper, wood and other raw materials and at least two outlets, and is used to screen out low-quality wood paper and bark resin as biomass raw materials into the crushing unit through one outlet, and the remaining high-quality parts into the pulping unit through another outlet to make pulp;

[0010] The pulverizing unit is used to pulverize low-quality wood paper and bark resin from the screening unit to form biomass powder, which enters the flow control unit I;

[0011] The flow control unit comprises a flow control unit I, a flow control unit II and a flow control unit III, wherein the flow control unit I has at least one inlet and at least three outlets, wherein one outlet is connected to the primary gasification unit, one outlet is connected to the combustion unit, and one outlet is connected to the pyrolysis unit; the flow control unit II has at least one inlet and at least two outlets, wherein one outlet is connected to the alkalization unit, and one outlet is connected to the primary gasification unit; the flow control unit III has at least three inlets and at least four outlets, wherein one inlet is connected to the carbon dioxide outlet of the separation unit, one inlet is connected to the carbon dioxide outlet of the heat transfer unit II, one inlet is connected to the water vapor outlet of the heat transfer unit II, one outlet is connected to the water vapor inlet of the water-gas shift unit, one outlet is connected to the carbon dioxide inlet of the secondary gasification unit, one outlet is connected to the carbon dioxide inlet of the heat transfer unit II, and one outlet is connected to the carbon dioxide inlet of the acidification unit;

[0012] The primary gasification unit is used to heat the coal and the biomass powder from the flow control unit I in isolation from air to produce coke and coke oven gas, the reaction temperature is 900-1000°C, and the coal and coke can react with CO2 at high temperature to produce CO;

[0013] The combustion unit is used to convert the chemical energy of coke oven gas and biomass powder into heat energy through combustion reaction, and the high-temperature flue gas formed enters the heat transfer unit I and transfers heat to the primary gasification unit and the secondary gasification unit at the same time. The biomass ash generated in the process enters the secondary gasification unit as a catalyst to increase the reaction rate and accelerate the process of secondary gasification;

[0014] The pyrolysis unit is used to pyrolyze the biomass powder at 500°C-700°C in an air-tight environment to produce biomass oil, which enters the secondary gasification unit;

[0015] In the secondary gasification unit, the biomass ash from the combustion unit is used as a catalyst, the reaction temperature is 800°C-1200°C, the crude carbon produced by the carbonization unit, the coke produced by the primary gasification unit, and the semi-coke and biomass oil produced by the pyrolysis unit react with carbon dioxide to generate carbon monoxide, and the carbon monoxide enters the water-gas shift unit;

[0016] The water-gas shift unit generates CO2 and H2 by reacting CO and water vapor under the action of a catalyst through a water-gas shift reaction, thereby increasing the proportion of H2 in the mixed gas. After sufficient reaction, the mixed gas enters a separation unit;

[0017] The heat transfer unit includes a heat transfer unit I and a heat transfer unit II. The heat transfer unit I is used to transfer the heat in the high-temperature flue gas generated by the combustion unit to the primary gasification unit and the secondary gasification unit, thereby reducing heat dissipation and increasing the stability of the reaction temperature of the two-stage gasification units. The heat transfer unit II transfers the heat brought by the CO2 from the water-gas shift unit and the water vapor from the fan heat exchange unit to the acidification unit and the carbonization unit to ensure that the reaction temperature is between 180°C and 210°C. The carbon dioxide and water vapor enter the flow control unit III after heat transfer.

[0018] The separation unit is used to separate hydrogen, carbon dioxide and water vapor from the mixed gas generated by the water-gas shift unit, and has at least one inlet and a hydrogen outlet, a carbon dioxide outlet and a water vapor outlet, wherein the inlet is connected to the secondary gasification unit, the hydrogen outlet is connected to the hydrogen inlet of the fuel cell, the carbon dioxide outlet is connected to a carbon dioxide inlet of the flow control unit III, and the water vapor outlet is connected to a water vapor inlet of the fan heat exchange unit;

[0019] The pulping unit has an inlet and an outlet, wherein the inlet is connected to the screening unit and the outlet is connected to the bleaching unit, and is used to make pulp from the high-quality wood after passing through the screening unit;

[0020] The bleaching unit is used to bleach the pulp produced by the pulping unit with a bleaching agent, and the pulp enters the drying unit after bleaching;

[0021] The drying unit is used to dry the paper that has passed through the bleaching unit with hot air to a desired dryness to produce a paper product, and has at least one hot air inlet and at least one product outlet;

[0022] The acidification unit is used to acidify the lignin in the black liquor to precipitate it. In a closed system, the acidifier CO2 introduced reacts with the lignin in the black liquor to convert the lignin into acidified lignin precipitation, and at the same time, the sodium salt in the black liquor is converted into NaHCO3, the sodium element is enriched and separated, and the inorganic silicon salt is also converted into SiO2 precipitation, which enters the carbonization unit together with the acidified lignin;

[0023] The carbonization unit cracks the acidified lignin produced by the acidification unit into small molecular organic matter under a hydrothermal environment and then cracks it into crude carbon containing SiO2 impurities. The crude carbon is respectively introduced into the alkalization unit and the secondary gasification unit through the flow control unit II to prepare activated carbon and graded gasification of coal.

[0024] The alkalization unit uses a dilute alkali solution to wash and remove SiO2 in the crude carbon produced by the carbonization unit to produce carbon powder, and the carbon powder is passed into the activation unit as a raw material for preparing activated carbon;

[0025] The activation unit is used to prepare activated carbon. Carbon powder is physically activated by water vapor to prepare activated carbon. The activated carbon is passed into the acidification unit to adsorb organic matter in black liquor.

[0026] The fuel cell has at least one hydrogen inlet and at least one oxygen inlet at its bottom, and H2 undergoes a redox reaction with O2 in the fuel cell through a separation unit to generate electricity, and at least one power supply circuit is provided at its top to supply electric energy to the fan heat exchange unit;

[0027] The fan heat exchange unit is powered by a fuel cell through a power supply circuit to rotate its fan to blow hot air toward the drying unit. It has at least two inlets and at least two outlets, one of which is connected to the water vapor outlet of the fuel cell, one is connected to a water vapor outlet of the separation unit, one is connected to the water vapor inlet of the heat transfer unit II, and one is connected to the hot air inlet of the drying unit.

[0028] A papermaking energy supply method for co-gasification of biomass and coal, the method comprising: waste paper, wood and other raw materials enter a screening unit, wherein high-quality raw materials enter a pulping unit, a bleaching unit, and a drying unit in sequence to obtain the final desired paper products; low-quality paper wood and bark resin enter a crushing unit for crushing to form biomass powder, the biomass powder passes through a flow control unit I and is divided into three biomass powder flows, the first flow of biomass powder enters a primary gasification unit through a pipeline, is isolated from coal by air heating, and is co-gasified to generate coke and coke oven gas, the reaction temperature is 900-1000°C, the heat required for this reaction is provided by the combustion unit through the heat transfer unit I Provided, coke oven gas flows into the combustion unit through a pipeline, and at the same time, the second stream of biomass powder enters the combustion unit and burns together with the coke oven gas, and the generated high-temperature flue gas transfers heat to the primary gasification unit and the secondary gasification unit through the heat transfer unit I. In addition, the ash that does not participate in the reaction enters the secondary gasification unit along the pipeline, and the third biomass stream enters the pyrolysis unit through the pipeline to isolate the air for heating. The reaction temperature is 500-700°C. The required heat is provided by the combustion unit through the heat transfer unit I to produce semi-coke, biomass oil and pyrolysis gas. The semi-coke and biomass oil enter the secondary gasification unit as secondary gasification raw materials, and the pyrolysis gas enters the combustion unit to burn and release heat;

[0029] In the secondary gasification unit, the biomass ash from the combustion unit is used as a catalyst to improve the reaction efficiency. The reaction temperature is 900-1200°C. The crude carbon produced by the carbonization unit, the coke produced by the primary gasification unit, the semi-coke produced by the pyrolysis unit, and the biomass oil react with CO2 to produce CO. The mixed gas of CO and the water vapor produced by the fuel cell enters the water-gas shift unit along the pipeline; in the water-gas shift unit, most of the carbon monoxide and water vapor react to produce carbon dioxide and hydrogen through the water-gas shift reaction, and the mixed gas after sufficient reaction enters the separation unit along the pipeline; in the separation unit, H2 enters the fuel cell through the pipeline to react with oxygen to generate electricity, and the water vapor enters the fan heat exchange unit to transfer heat to the air through heat exchange to generate hot air, which is blown out by the fan, and the hot air enters the drying unit, and the carbon dioxide enters the flow control unit III; in the fuel cell, the water vapor generated by the reaction of hydrogen and oxygen also enters the fan heat exchange unit for heat exchange, and at the same time, the power supply circuit provides electric energy for the fan heat exchange unit; in the fan heat exchange unit, the water vapor after sufficient heat exchange enters the heat transfer unit II; in the flow control unit III, the carbon dioxide after the separation unit is divided into three The first stream enters the acidification unit through a pipeline as an acidifier to react with the lignin in the black liquor to precipitate lignin. The second stream re-enters the secondary gasification unit to react with the semi-coke, biomass oil and coke produced by the pyrolysis unit and the primary gasification unit to generate carbon monoxide. The third stream transfers heat to the acidification unit and the carbonization unit through the heat transfer unit II to maintain the reaction temperature. In the heat transfer unit II, the water vapor from the fan heat exchange unit enters the flow control unit III after heat exchange, and a stream of carbon dioxide from the flow control unit III re-enters the flow control unit III after heat exchange. The black liquor produced in the Yuanhe bleaching unit process enters the acidification unit along the pipeline, reacts with the carbon dioxide from the flow control unit III in a closed system to produce acidified lignin precipitation, and the acidified lignin enters the carbonization unit to crack at a temperature of 180℃-210℃ to produce crude carbon; the crude carbon is divided into two streams by the flow control unit II, one stream enters the alkalization unit, and the other stream enters the primary gasification unit; in the alkalization unit, the crude carbon is washed with dilute alkali solution to remove SiO2 in the crude carbon to produce carbon powder; the carbon powder forms activated carbon in the activation unit, and is passed into the acidification unit as an adsorbent to adsorb organic matter in the black liquor.

[0030] The beneficial effects produced by the present invention are:

[0031] (1) The selected low-quality paper wood and bark resin are crushed into biomass powder to replace part of the coal, reducing the use of fossil fuels from the source, reducing CO2 emissions to a certain extent, and making energy cleaner.

[0032] (2) A portion of the biomass powder is burned, and the resulting biomass ash is used as a catalyst for coal graded gasification. The waste heat of high-temperature flue gas and water vapor generated during the co-gasification of biomass and coal is fully utilized to achieve deep coupling of biomass energy and coal chemical energy, increase the gasification reaction rate, and effectively reduce the heat dissipation of the system.

[0033] (3) A series of processes such as acidification, alkalization, carbonization, and activation are used to treat black liquor. The crude carbon produced can be used as a gasification raw material to participate in coal graded gasification, and can also recover important chemical raw material NaHCO3, thereby reducing environmental pollution and achieving full utilization of black liquor.

[0034] (4) A portion of the CO2 produced by the water-gas reaction is used in the water-gas reaction, and a portion is used as an acidifier to react with sodium lignin sulfonate. The generated water vapor is heat-exchanged with the water vapor produced by the fuel cell, and then is put back into the water-gas reaction, thus realizing the recycling of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a papermaking energy supply system for co-gasification of biomass and coal provided by the present invention;

[0036] Figure 2 A flow chart of a papermaking energy supply method for co-gasification of biomass and coal provided by the present invention;

[0037] Figure 3 for Figure 1 Schematic diagram of another papermaking energy supply system using co-gasification of biomass and coal;

[0038] Among them, 1-screening unit, 2-pulping unit, 3-bleaching unit, 4-drying unit, 5-crushing unit, 6-flow control unit I, 7-pyrolysis unit, 8-secondary gasification unit, 9-combustion unit, 10-primary gasification unit, 11-heat transfer unit I, 12-acidification unit, 13-carbonization unit, 14-flow control unit II, 15-alkalization unit, 16-activation unit, 17-water-gas shift unit, 18-separation unit, 19-fuel cell, 20-fan heat exchange unit, 21-flow control unit III, 22-heat transfer unit II. DETAILED DESCRIPTION

[0039] The purpose and technical solution of the present invention are described in detail below with reference to the accompanying drawings and in combination with embodiments;

[0040] like Figure 1 As shown, Figure 1It is a system diagram of a papermaking energy supply method for co-gasification of biomass and coal provided by the present invention, and the system includes: a screening unit 1, a pulping unit 2, a bleaching unit 3, a drying unit 4, a crushing unit 5, a flow control unit I6, a pyrolysis unit 7, a secondary gasification unit 8, a combustion unit 9, a primary gasification unit 10, a heat transfer unit I11, an acidification unit 12, a carbonization unit 13, a flow control unit II14, an alkalization unit 15, an activation unit 16, a water-gas shift unit 17, a separation unit 18, a fuel cell 19, a fan heat exchange unit 20, a flow control unit III21, and a heat transfer unit II22.

[0041] The screening unit 1 has at least one papermaking raw material inlet and at least two outlets, and is used to screen out low-quality wood, paper and bark resin as biomass raw materials to enter the crushing unit 5 through one outlet, and the remaining high-quality parts to enter the pulping unit 2 through another outlet to make pulp;

[0042] The pulping unit 2 has an inlet and an outlet, wherein the inlet is connected to the screening unit 1, and the outlet is connected to the bleaching unit 3, and is used to make pulp from the high-quality wood after passing through the screening unit 1;

[0043] The bleaching unit 3 is used to bleach the pulp produced by the pulping unit 2 with a bleaching agent, and the pulp enters the drying unit 4 after bleaching;

[0044] The drying unit 4 is used to dry the paper that has passed through the bleaching unit 3 with hot air to a desired dryness to produce a paper product, and has at least one hot air inlet and at least one product outlet;

[0045] A crushing unit 5 is used to crush low-quality wood, paper and bark resin from the screening unit 1 to form biomass powder, and the generated biomass powder enters the flow control unit I 6;

[0046] The flow control unit I6 has at least one inlet and at least three outlets, one of which is connected to the primary gasification unit 10, one is connected to the combustion unit 9, and one is connected to the pyrolysis unit 7. The biomass powder is respectively introduced into the primary gasification unit 10, the combustion unit 9, and the pyrolysis unit 7 through the flow control unit I6. A part of the biomass powder is co-gasified with coal in the primary gasification unit 10 to increase the output of coke and coke oven gas. A part of the biomass powder is burned and released heat in the combustion unit 9 to produce biomass ash as a catalyst for the secondary gasification unit 8. A part of the biomass powder enters the pyrolysis unit 7 and is pyrolyzed at a relatively low temperature to produce semi-coke, biomass oil, and pyrolysis gas.

[0047] The pyrolysis unit 7 is used to isolate the biomass powder from the air for pyrolysis to produce semi-coke, biomass oil and pyrolysis gas. The semi-coke and biomass oil are used as secondary gasification raw materials to enter the secondary gasification unit 8, and the pyrolysis gas enters the combustion unit 9;

[0048] The secondary gasification unit 8 uses the biomass ash produced by the combustion unit 9 as a catalyst, and the crude carbon produced by the carbonization unit 13, the coke produced by the primary gasification unit 10, and the semi-coke and biomass oil produced by the pyrolysis unit 7 react with carbon dioxide to generate carbon monoxide, which enters the water-gas shift unit 17;

[0049] The combustion unit 9 is used to convert the chemical energy of the coke oven gas, pyrolysis gas and biomass powder into heat energy through the combustion reaction, and the high-temperature flue gas formed enters the heat transfer unit I 11, and at the same time transfers heat to the primary gasification unit 10 and the secondary gasification unit 8. The biomass ash generated by the combustion enters the secondary gasification unit 8 as a catalyst;

[0050] The primary gasification unit 10 is used to isolate the air from the coal and the biomass powder flowing into the pulverization unit 5 through the flow control unit I 6 and heat it to produce coke and coke oven gas. The coke flows into the secondary gasification unit 8 as a gasification raw material.

[0051] The heat transfer unit I 11 is used to transfer the heat in the high-temperature flue gas generated by the combustion unit 9 to the primary gasification unit 10 and the secondary gasification unit 8;

[0052] The acidification unit 12 is used to acidify the lignin in the black liquor to precipitate it. In a closed system, the acidifier CO2 introduced reacts with the lignin in the black liquor to convert the lignin into acidified lignin precipitation, and at the same time, the sodium salt in the black liquor is converted into NaHCO3, the sodium element is enriched and separated, and the inorganic silicon salt is also converted into SiO2 precipitation, which enters the carbonization unit 13 together with the acidified lignin;

[0053] The carbonization unit 13 decomposes the acidified lignin produced by the acidification unit 12 into small molecular organic matter under a hydrothermal environment and then decomposes it into crude carbon containing SiO2 impurities;

[0054] The flow control unit II 14 has at least one inlet and at least two outlets, the inlet is connected to the crude carbon outlet of the carbonization unit 13, one of the outlets is connected to the alkalization unit 15, and one of the outlets is connected to the primary gasification unit 10. The crude carbon is respectively introduced into the alkalization unit 15 and the secondary gasification unit 8 through the flow control unit II 14. A part of the crude carbon is purified into carbon powder in the alkalization unit 15, and the carbon powder enters the activation unit 16 as a raw material for preparing activated carbon, and a part of the crude carbon enters the secondary gasification unit 8 to react with CO2 to produce CO;

[0055] The alkalization unit 15 uses a dilute alkali solution to wash and remove SiO2 in the crude carbon produced by the carbonization unit 13 to produce carbon powder, which is passed into the activation unit 16 as a raw material for preparing activated carbon;

[0056] The activation unit 16 is used to prepare activated carbon. The carbon powder is physically activated by water vapor to prepare activated carbon. The activated carbon is passed into the acidification unit 12 to adsorb organic matter in the black liquor.

[0057] The water-gas shift unit 17 is used to generate CO2 and H2 from CO and water vapor under the action of a catalyst, thereby increasing the proportion of H2 in the mixed gas. After sufficient reaction, the mixed gas enters the separation unit 18;

[0058] The separation unit 18 is used to separate hydrogen, carbon dioxide and water vapor from the mixed gas generated by the water-gas shift unit 17, and has at least one inlet and a hydrogen outlet, a carbon dioxide outlet and a water vapor outlet, wherein the inlet is connected to the secondary gasification unit 8, the hydrogen outlet is connected to the hydrogen inlet of the fuel cell 19, the carbon dioxide outlet is connected to a carbon dioxide inlet of the flow control unit III 21, and the water vapor outlet is connected to a water vapor inlet of the fan heat exchange unit 20;

[0059] The fuel cell 19 has at least one hydrogen inlet and at least one oxygen inlet. H2 passes through the separation unit 18 and undergoes a redox reaction with O2 in the fuel cell 19 to generate electricity. At least one power supply circuit is provided to supply electric energy to the fan heat exchange unit 20.

[0060] The fan heat exchange unit 20 is used to recover the heat of the high-temperature H20 stream and convert the heat into hot air as the heat source of the drying unit 4, and includes a fan a and a heat exchange tube coil b. It has at least two inlets and at least two outlets, one of which is connected to the water vapor outlet of the fuel cell 19, one inlet is connected to a water vapor outlet of the separation unit 18, one outlet is connected to the water vapor inlet of the heat transfer unit II 22, and one outlet is connected to the hot air inlet of the drying unit 4. The high-temperature H20 stream generated by the fuel cell 19 enters the heat exchange tube coil b, and the fan a performs forced convection heat exchange on the heat exchange tube coil b, cooling the H20 stream and generating hot air at the same time. The electric energy consumed by the fan a is provided by the fuel cell 19 through the power supply circuit;

[0061] The flow control unit III 21 has at least three inlets and at least four outlets, one inlet is connected to the carbon dioxide outlet of the separation unit 18, one inlet is connected to the carbon dioxide outlet of the heat transfer unit II 22, one inlet is connected to the water vapor outlet of the heat transfer unit II 22, one outlet is connected to the water vapor inlet of the water-gas shift unit 17, one outlet is connected to the carbon dioxide inlet of the secondary gasification unit 8, one outlet is connected to the carbon dioxide inlet of the heat transfer unit II 22, and one outlet is connected to the carbon dioxide inlet of the acidification unit 12. The CO2 stream separated by the separation unit 18 is divided into a heat transfer stream c and a mass transfer stream d through the flow control unit III 21. The heat transfer stream c provides heat for the acidification unit 12 and the carbonization unit 13 through the heat transfer unit II 22. A part of the mass transfer stream d enters the acidification unit 12 as an acidulant to acidify the lignin in the black liquor to convert it into acidified lignin precipitation, and a part enters the secondary gasification unit 8 as a gasifying agent to react with the crude carbon produced by the carbonization unit 13, the coke produced by the primary gasification unit 10, and the semi-coke produced by the pyrolysis unit 7 and the biomass oil to produce CO2;

[0062] The heat transfer unit II 22 transfers the heat of CO2 from the water-gas shift unit 17 and the water vapor from the fan heat exchange unit 20 to the acidification unit 12 and the carbonization unit 13. The carbon dioxide and water vapor enter the flow control unit III 21 after heat transfer.

[0063] The flow control unit I6 is used to adjust the proportion of biomass powder passing into the primary gasification unit 10, the combustion unit 9, and the pyrolysis unit 7 respectively. The adjustable range of the proportion of biomass powder passing into the primary gasification unit 10 to the biomass powder input to the flow control unit I6 is 0-100%, 0% means that the biomass powder only enters the combustion unit 9 and the pyrolysis unit 7 through the flow control unit I6, and 100% means that the biomass powder only enters the primary gasification unit 10 through the flow control unit I6; the proportion of biomass powder passing into the combustion unit 9 to the biomass powder input to the flow control unit I6 The adjustable range is 0-100%, 0% means that the biomass powder only enters the primary gasification unit 10 and the pyrolysis unit 7 through the flow control unit Ⅰ6, and 100% means that the biomass powder only enters the combustion unit 9 through the flow control unit Ⅰ6; the adjustable range of the proportion of the biomass powder entering the pyrolysis unit 7 to the biomass powder input to the flow control unit Ⅰ6 is 0-100%, 0% means that the biomass powder only enters the combustion unit 9 and the primary gasification unit 10 through the flow control unit Ⅰ6, and 100% means that the biomass powder only enters the pyrolysis unit 7 through the flow control unit Ⅰ6.

[0064] The flow control unit II14 is used to adjust the ratio of the crude carbon passing into the alkalization unit 15 and the secondary gasification unit 8 respectively, and the adjustment range is 0-100%, 0% means that the crude carbon passes through the flow control unit II14 and is completely passed into the secondary gasification unit 8 as a gasification raw material, and 100% means that the crude carbon passes through the flow control unit II14 and is completely passed into the alkalization unit 15 for the preparation of activated carbon.

[0065] The flow control unit III 21 is used to adjust the ratio of CO2 heat transfer stream c and mass transfer stream d, and the adjustment range is 0-100%. 0% means that all CO2 enters the acidification unit 12 and the secondary gasification unit 8 respectively as the mass transfer stream d, and 100% means that all CO2 enters the acidification unit 12 and the secondary gasification unit 8 as the heat transfer stream c through the heat transfer unit II 22 to provide heat for the acidification unit 12 and the carbonization unit 13; the flow control unit III 21 is also used to adjust the ratio of CO2 entering the acidification unit 12 and the secondary gasification unit 8 respectively as the mass transfer stream d, and the adjustment range is 0-100%. 0% means that all CO2 mass transfer stream d enters the secondary gasification unit 8 as a gasifying agent, and 100% means that all CO2 mass transfer stream d enters the acidification unit 12 as an acidifying agent.

[0066] The heat exchange tube coil b of the fan heat exchange unit 20 adopts finned tubes, and has two forms: single coil and multi-coil.

[0067] The embodiment is applied to a papermaking energy supply method for co-gasification of biomass and coal, the method comprising: papermaking raw materials such as waste paper and wood enter the screening unit 1, wherein high-quality raw materials enter the pulping unit 2, the bleaching unit 3, and the drying unit 4 in sequence to obtain the final desired paper products; low-quality paper wood and bark resin enter the crushing unit 5 for crushing to form biomass powder, the biomass powder passes through the flow control unit Ⅰ6, and is divided into three biomass powder flows, the first stream of biomass powder enters the primary gasification unit 10 through a pipeline, is isolated from the coal by air heating, and is co-gasified to generate coke and coke oven gas, the reaction temperature is 900-1000°C, and the heat required for this reaction is provided by the combustion unit 9 through heat transfer Unit I11 provides, coke oven gas flows into the combustion unit through a pipeline, and at the same time, the second stream of biomass powder enters the combustion unit 9 and burns together with the coke oven gas. The generated high-temperature flue gas transfers heat to the primary gasification unit 10 and the secondary gasification unit 8 through the heat transfer unit I11. In addition, the ash that does not participate in the reaction enters the secondary gasification unit 8 along the pipeline. The third biomass stream enters the pyrolysis unit 7 through the pipeline to isolate the air for heating. The reaction temperature is 500-700°C. The required heat is provided by the combustion unit through the heat transfer unit I11 to produce semi-coke, biomass oil and pyrolysis gas. The semi-coke and biomass oil enter the secondary gasification unit 8 as secondary gasification raw materials, and the pyrolysis gas enters the combustion unit 9 to burn and release heat;

[0068] In the secondary gasification unit 8, the biomass ash from the combustion unit 9 is used as a catalyst to improve the reaction efficiency. The reaction temperature is 900-1200°C. The crude carbon produced by the carbonization unit 13, the coke produced by the primary gasification unit 10, the semi-coke produced by the pyrolysis unit 7, and the biomass oil react with CO2 to produce CO. The mixed gas of CO and the water vapor produced by the fuel cell 19 enters the water-gas shift unit 17 along the pipeline; in the water-gas shift unit 17, most of the carbon monoxide reacts with the water vapor to produce carbon dioxide and hydrogen through the water-gas shift reaction, and the mixed gas after the full reaction enters the separation unit 18 along the pipeline; in the separation unit 1 8, H2 enters the fuel cell 19 through the pipeline to react with oxygen to generate electricity, water vapor enters the fan heat exchange unit 20 to transfer heat to the air through heat exchange to generate hot air, which is blown out by the fan, and the hot air enters the drying unit 4, and carbon dioxide enters the flow control unit III 21; in the fuel cell 19, water vapor generated by the reaction of hydrogen and oxygen also enters the fan heat exchange unit 20 for heat exchange, and at the same time, electric energy is provided to the fan heat exchange unit 20 through the power supply circuit; in the fan heat exchange unit 20, the water vapor after sufficient heat exchange enters the heat transfer unit II 22; in the flow control unit III 21, the carbon dioxide after passing through the separation unit is divided into three streams The first stream enters the acidification unit 12 through the pipeline as an acidifier, reacts with the lignin in the black liquor to precipitate lignin, the second stream re-enters the secondary gasification unit 8 to react with the semi-coke produced by the pyrolysis unit 7, biomass oil and coke produced by the primary gasification unit 10 to generate carbon monoxide, and the third stream transfers heat to the acidification unit 12 and the carbonization unit 13 through the heat transfer unit II 22 to maintain the reaction temperature; in the heat transfer unit II 22, the water vapor from the fan heat exchange unit 20 enters the flow control unit III 21 after heat exchange, and a stream of carbon dioxide from the flow control unit III 21 re-enters the flow control unit III 21 after heat exchange; the pulping unit The black liquor produced during the process of element 2 and bleaching unit 3 enters the acidification unit 12 along the pipeline, reacts with the carbon dioxide from the flow control unit III 21 in a closed system to produce acidified lignin precipitation, and the acidified lignin enters the carbonization unit 13 to crack at a temperature of 180°C-210°C to produce crude carbon; the crude carbon is divided into two streams by the flow control unit II 14, one stream enters the alkalization unit 15, and the other stream enters the primary gasification unit 10; in the alkalization unit 15, the crude carbon is washed with dilute alkali solution to remove SiO2 in the crude carbon to produce carbon powder; the carbon powder forms activated carbon in the activation unit 16, and is passed into the acidification unit 12 as an adsorbent to adsorb organic matter in the black liquor.

[0069] As attached Figure 3In one embodiment shown, the CO2 stream separated by the separation unit 18 flows to the acidification unit 12 and the secondary gasification unit 8 respectively through the flow control unit III 21. The CO2 stream enters the acidification unit 12 as an acidifying agent to react with the lignin in the black liquor to convert the lignin into acidified lignin precipitation. The CO2 stream can also enter the secondary gasification unit 8 as a gasifying agent to react with the crude carbon produced by the carbonization unit 13, the coke produced by the primary gasification unit 10, and the semi-coke and biomass oil produced by the pyrolysis unit 7 to produce CO. In this embodiment, the CO2 stream separated by the separation unit 18 passes through the flow control unit III 21 and no longer enters the fan heat exchange unit 20 for heat exchange.

[0070] In another embodiment, the biomass powder flows to the combustion unit 9 and the primary gasification unit 10 respectively through the flow control unit Ⅰ6. The biomass powder burns and releases heat in the combustion unit 9 to produce high-temperature flue gas and biomass ash. The biomass ash serves as a catalyst for the secondary gasification unit 8. The biomass powder is used as a gasification raw material and is co-gasified with coal in the primary gasification unit 10. In this embodiment, the biomass powder no longer flows into the pyrolysis unit 7 through the flow control unit Ⅰ6.

[0071] Therefore, those skilled in the art should understand that the description of the specific embodiments of the present invention is not intended to limit the concept and scope of the present invention. Without departing from the technical solution of the present invention, any modification and improvement of the technical solution will still fall within the protection scope of the present invention.

Claims

1. A papermaking energy supply system for co-gasification of biomass and coal, characterized in that: The invention comprises a screening unit (1), a pulping unit (2), a bleaching unit (3), a drying unit (4), a pulverizing unit (5), a flow control unit I (6), a pyrolysis unit (7), a secondary gasification unit (8), a combustion unit (9), a primary gasification unit (10), a heat transfer unit I (11), an acidification unit (12), a carbonization unit (13), a flow control unit II (14), an alkalization unit (15), an activation unit (16), a water-gas shift unit (17), a separation unit (18), a fuel cell (19), a fan heat exchange unit (20), a flow control unit III (21), and a heat transfer unit II (22), wherein: The screening unit (1) has at least one papermaking raw material inlet and at least two outlets, and is used to screen out low-quality wood, paper and bark resin as biomass raw materials and enter the crushing unit (5) through one outlet, and the remaining high-quality parts enter the pulping unit (2) through another outlet to make pulp; A pulping unit (2) having an inlet and an outlet, wherein the inlet is connected to the screening unit (1) and the outlet is connected to the bleaching unit (3), and is used to make pulp from high-quality wood after passing through the screening unit (1); A bleaching unit (3) is used to bleach the pulp produced by the pulping unit (2) with a bleaching agent, and the pulp enters the drying unit (4) after bleaching; A drying unit (4), used for drying the paper that has passed through the bleaching unit (3) with hot air to a desired dryness to produce a paper product, and having at least one hot air inlet and at least one product outlet; A pulverizing unit (5) is used to pulverize low-quality wood, paper and bark resin from the screening unit (1) to form biomass powder, and the generated biomass powder enters the flow control unit I (6); A flow control unit I (6) has at least one inlet and at least three outlets, wherein one outlet is connected to a primary gasification unit (10), one outlet is connected to a combustion unit (9), and one outlet is connected to a pyrolysis unit (7). Biomass powder is respectively introduced into the primary gasification unit (10), the combustion unit (9), and the pyrolysis unit (7) through the flow control unit I (6). A portion of the biomass powder is co-gasified with coal in the primary gasification unit (10) to increase the output of coke and coke oven gas. A portion of the biomass powder is burned and released heat in the combustion unit (9) to produce biomass ash as a catalyst for the secondary gasification unit (8). A portion of the biomass powder enters the pyrolysis unit (7) and is pyrolyzed at a relatively low temperature to produce semi-coke, biomass oil, and pyrolysis gas. The pyrolysis unit (7) is used to isolate the biomass powder from air and perform pyrolysis to produce semi-coke, biomass oil and pyrolysis gas. The semi-coke and biomass oil are used as secondary gasification raw materials and enter the secondary gasification unit (8), and the pyrolysis gas enters the combustion unit (9); The secondary gasification unit (8) uses the biomass ash produced by the combustion unit (9) as a catalyst, and the crude carbon produced by the carbonization unit (13), the coke produced by the primary gasification unit (10), the semi-coke produced by the pyrolysis unit (7), and the biomass oil react with carbon dioxide to generate carbon monoxide, which enters the water-gas shift unit (17); The combustion unit (9) is used to convert the chemical energy of the coke oven gas, pyrolysis gas and biomass powder into heat energy through a combustion reaction, and the high-temperature flue gas formed enters the heat transfer unit I (11), and simultaneously transfers heat to the primary gasification unit (10) and the secondary gasification unit (8), and the biomass ash generated by the combustion enters the secondary gasification unit (8) as a catalyst; The primary gasification unit (10) is used to heat the coal and biomass powder flowing into the pulverization unit (5) through the flow control unit I (6) in isolation from air to produce coke and coke oven gas, and the coke flows into the secondary gasification unit (8) as a gasification raw material; A heat transfer unit I (11), used for transferring heat from the high-temperature flue gas generated by the combustion unit (9) to the primary gasification unit (10) and the secondary gasification unit (8); The acidification unit (12) is used to acidify the lignin in the black liquor to precipitate it. In a closed system, the acidifier CO2 is introduced to react with the lignin in the black liquor to convert the lignin into acidified lignin precipitation. At the same time, the sodium salt in the black liquor is converted into NaHCO3, the sodium element is enriched and separated, and the inorganic silicon salt is also converted into SiO2 precipitation, which enters the carbonization unit (13) together with the acidified lignin; The carbonization unit (13) decomposes the acidified lignin produced by the acidification unit (12) into small molecular organic matter and then decomposes it into crude carbon containing SiO2 impurities under a hydrothermal environment; A flow control unit II (14) has at least one inlet and at least two outlets, wherein the inlet is connected to the crude carbon outlet of the carbonization unit (13), one of the outlets is connected to the alkalization unit (15), and one of the outlets is connected to the primary gasification unit (10). The crude carbon is respectively introduced into the alkalization unit (15) and the secondary gasification unit (8) through the flow control unit II (14). A portion of the crude carbon is purified into carbon powder in the alkalization unit (15), and the carbon powder enters the activation unit (16) as a raw material for preparing activated carbon, and a portion of the crude carbon enters the secondary gasification unit (8) to react with CO2 to produce CO; The alkalization unit (15) uses a dilute alkali solution to wash and remove SiO2 in the crude carbon produced by the carbonization unit (13) to produce carbon powder, which is then introduced into the activation unit (16) as a raw material for preparing activated carbon; The activation unit (16) is used to prepare activated carbon. The carbon powder is physically activated by water vapor to prepare activated carbon. The activated carbon is introduced into the acidification unit (12) to adsorb organic matter in the black liquor. A water-gas shift unit (17) is used to generate CO2 and H2 from CO and water vapor under the action of a catalyst, thereby increasing the proportion of H2 in the mixed gas. After sufficient reaction, the mixed gas enters a separation unit (18); A separation unit (18) for separating hydrogen, carbon dioxide and water vapor from the mixed gas generated by the water-gas shift unit (17), having at least one inlet and a hydrogen outlet, a carbon dioxide outlet and a water vapor outlet, wherein the inlet is connected to the secondary gasification unit (8), the hydrogen outlet is connected to the hydrogen inlet of the fuel cell (19), the carbon dioxide outlet is connected to a carbon dioxide inlet of the flow control unit III (21), and the water vapor outlet is connected to a water vapor inlet of the fan heat exchange unit (20); The fuel cell (19) has at least one hydrogen inlet and at least one oxygen inlet. H2 passes through the separation unit (18) and undergoes a redox reaction with O2 in the fuel cell (19) to generate electricity. At least one power supply circuit is provided to supply electric energy to the fan heat exchange unit (20). A fan heat exchange unit (20) is used to recover heat from a high-temperature H20 stream and convert the heat into hot air as a heat source for a drying unit (4), comprising a fan (a) and a heat exchange tube coil (b), having at least two inlets and at least two outlets, wherein one inlet is connected to a water vapor outlet of a fuel cell (19), one inlet is connected to a water vapor outlet of a separation unit (18), one outlet is connected to a water vapor inlet of a heat transfer unit II (22), and one outlet is connected to a hot air inlet of a drying unit (4). The high-temperature H20 stream generated by the fuel cell (19) enters the heat exchange tube coil (b), and the fan (a) performs forced convection heat exchange on the heat exchange tube coil (b), thereby cooling the H20 stream and generating hot air at the same time. The electric energy consumed by the fan (a) is provided by the fuel cell (19) through a power supply circuit; The flow control unit III (21) has at least three inlets and at least four outlets, one inlet connected to the carbon dioxide outlet of the separation unit (18), one inlet connected to the carbon dioxide outlet of the heat transfer unit II (22), one inlet connected to the water vapor outlet of the heat transfer unit II (22), one outlet connected to the water vapor inlet of the water gas shift unit (17), one outlet connected to the carbon dioxide inlet of the secondary gasification unit (8), one outlet connected to the carbon dioxide inlet of the heat transfer unit II (22), and one outlet connected to the carbon dioxide inlet of the acidification unit (12). The separation unit (18) The separated CO2 stream is divided into a heat transfer stream (c) and a mass transfer stream (d) through a flow control unit III (21). The heat transfer stream (c) provides heat for the acidification unit (12) and the carbonization unit (13) through the heat transfer unit II (22). A portion of the mass transfer stream (d) enters the acidification unit (12) as an acidifying agent to acidify the lignin in the black liquor to convert it into acidified lignin precipitation, and a portion enters the secondary gasification unit (8) as a gasifying agent to react with the crude carbon produced by the carbonization unit (13), the coke produced by the primary gasification unit (10), the semi-coke produced by the pyrolysis unit (7) and the biomass oil to produce CO2. The heat transfer unit II (22) transfers the heat of CO2 from the water-gas shift unit (17) and the heat carried by the water vapor from the fan heat exchange unit (20) to the acidification unit (12) and the carbonization unit (13). After the heat transfer, the carbon dioxide and the water vapor enter the flow control unit III (21).

2. A papermaking energy supply system for co-gasification of biomass and coal, characterized in that: The flow control unit I (6) is used to adjust the proportion of biomass powder respectively entering the primary gasification unit (10), the combustion unit (9), and the pyrolysis unit (7). The adjustable range of the proportion of biomass powder entering the primary gasification unit (10) to the biomass powder input to the flow control unit I (6) is 0-100%, 0% means that the biomass powder only enters the combustion unit (9) and the pyrolysis unit (7) through the flow control unit I (6), and 100% means that the biomass powder only enters the primary gasification unit (10) through the flow control unit I (6); the proportion of biomass powder entering the combustion unit (9) to the biomass powder input to the flow control unit I (6) is The adjustable range of the example is 0-100%, 0% means that the biomass powder only enters the primary gasification unit (10) and the pyrolysis unit (7) through the flow control unit I (6), and 100% means that the biomass powder only enters the combustion unit (9) through the flow control unit I (6); the adjustable range of the proportion of the biomass powder entering the pyrolysis unit (7) to the biomass powder input to the flow control unit I (6) is 0-100%, 0% means that the biomass powder only enters the combustion unit (9) and the primary gasification unit (10) through the flow control unit I (6), and 100% means that the biomass powder only enters the pyrolysis unit (7) through the flow control unit I (6).

3. A papermaking energy supply system for co-gasification of biomass and coal, characterized in that: The flow control unit II (14) is used to adjust the ratio of the crude carbon respectively entering the alkalization unit (15) and the secondary gasification unit (8), and the adjustment range is 0-100%, 0% means that the crude carbon is completely passed through the flow control unit II (14) into the secondary gasification unit (8) as a gasification raw material, and 100% means that the crude carbon is completely passed through the flow control unit II (14) into the alkalization unit (15) for the preparation of activated carbon.

4. A papermaking energy supply system for co-gasification of biomass and coal, characterized in that: The flow control unit III (21) is used to adjust the ratio of the CO2 heat transfer stream (c) to the mass transfer stream (d), and the adjustment range is 0-100%. 0% means that all the CO2 enters the acidification unit (12) and the secondary gasification unit (8) as the mass transfer stream (d), and 100% means that all the CO2 enters the acidification unit (12) and the secondary gasification unit (13) as the heat transfer stream (c) through the heat transfer unit II (22). The flow control unit III (21) is also used to adjust the ratio of the CO2 entering the acidification unit (12) and the secondary gasification unit (8) as the mass transfer stream (d), and the adjustment range is 0-100%. 0% means that all the CO2 mass transfer stream (d) enters the secondary gasification unit (8) as a gasifying agent, and 100% means that all the CO2 mass transfer stream (d) enters the acidification unit (12) as an acidifying agent.

5. A papermaking energy supply system for co-gasification of biomass and coal, characterized in that: The heat exchange tube coil (b) of the fan heat exchange unit (20) adopts finned tubes and has two forms: single coil and multi-coil.

6. A papermaking energy supply method for co-gasification of biomass and coal, applied to the system described in any one of claims 1-5, characterized in that: The method includes: The papermaking raw materials enter the screening unit (1), wherein the high-quality raw materials enter the pulping unit (2), bleaching unit (3), and drying unit (4) in turn to obtain the final desired paper products; the low-quality paper wood and bark resin enter the crushing unit (5) to be crushed to form biomass powder. The biomass powder passes through the flow control unit I (6) and is divided into three biomass powder flows. The first flow of biomass powder enters the primary gasification unit (10) through a pipeline to be isolated from the coal and heated by air to form coke and coke oven gas. The reaction temperature is 900-1000°C. The heat required for this reaction is provided by the combustion unit (9) through the heat transfer unit I (11). The coke oven gas flows into the combustion unit (10) through a pipeline. 9), at the same time, the second stream of biomass powder enters the combustion unit (9) and burns together with the coke oven gas, and the generated high-temperature flue gas transfers heat to the primary gasification unit (10) and the secondary gasification unit (8) through the heat transfer unit I (11). In addition, the ash that does not participate in the reaction enters the secondary gasification unit (8) along the pipeline. The third biomass stream enters the pyrolysis unit (7) through the pipeline to be isolated from the air for heating. The reaction temperature is 500-700° C. The required heat is provided by the combustion unit (9) through the heat transfer unit I (11), and semi-coke, biomass oil and pyrolysis gas are generated. The semi-coke and biomass oil enter the secondary gasification unit (8) as secondary gasification raw materials, and the pyrolysis gas enters the combustion unit (9) to burn and release heat; In the secondary gasification unit (8), the biomass ash from the combustion unit (9) is used as a catalyst to improve the reaction efficiency. The reaction temperature is 900-1200°C. The crude carbon produced by the carbonization unit (13), the coke produced by the primary gasification unit (10), the semi-coke produced by the pyrolysis unit (7), and the biomass oil react with CO2 to produce CO. The CO and the water vapor produced by the fuel cell (19) are mixed into a water-gas shift unit (17) through a pipeline. In the water-gas shift unit (17), most of the carbon monoxide reacts with the water vapor to produce carbon dioxide and hydrogen through a water-gas shift reaction. The fully reacted mixed gas enters a separation unit (18) through a pipeline. In the separation unit (18), , H2 enters the fuel cell (19) through the pipeline and reacts with oxygen to generate electricity, water vapor enters the fan heat exchange unit (20) and transfers heat to the air through heat exchange to generate hot air, which is blown out by the fan, and the hot air enters the drying unit (4), and carbon dioxide enters the flow control unit III (21); in the fuel cell (19), water vapor generated by the reaction of hydrogen and oxygen also enters the fan heat exchange unit (20) for heat exchange, and at the same time, electric energy is provided to the fan heat exchange unit (20) through the power supply circuit; in the fan heat exchange unit (20), the water vapor after sufficient heat exchange enters the heat transfer unit II (22); in the flow control unit III (21), the carbon dioxide after passing through the separation unit (18) is divided into three streams, The first stream enters the acidification unit (12) through a pipeline as an acidifier to react with the lignin in the black liquor to precipitate the lignin. The second stream re-enters the secondary gasification unit (8) to react with the semi-coke produced by the pyrolysis unit (7), biomass oil and the coke produced by the primary gasification unit (10) to generate carbon monoxide. The third stream transfers heat to the acidification unit (12) and the carbonization unit (13) through the heat transfer unit II (22) to maintain the reaction temperature. In the heat transfer unit II (22), the water vapor from the fan heat exchange unit (20) enters the flow control unit III (21) after heat exchange, and a stream of carbon dioxide from the flow control unit III (21) re-enters the flow control unit III (21) after heat exchange. The black liquor produced in the process of the bleaching unit (2) and the bleaching unit (3) enters the acidification unit (12) along the pipeline, reacts with the carbon dioxide from the flow control unit III (21) in a closed system to produce acidified lignin precipitation, and the acidified lignin enters the carbonization unit (13) and is cracked at a temperature of 180°C-210°C to produce crude carbon; the crude carbon is divided into two streams through the flow control unit II (14), one stream enters the alkalization unit (15), and the other stream enters the primary gasification unit (10); in the alkalization unit (15), the crude carbon is washed with diluted alkali solution to remove SiO2 in the crude carbon to produce carbon powder; the carbon powder forms activated carbon in the activation unit (16), and is passed into the acidification unit (12) as an adsorbent to adsorb organic matter in the black liquor.

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