A method and system for the combined production of biomass pyrolysis and magnesite calcination

Abstract

This invention discloses a multi-product method and system for biomass pyrolysis coupled with magnesite calcination. The main process involves pyrolyzing biomass feedstock in a biomass pyrolysis furnace to produce biochar and biogas. The biogas is then fed into a combustion chamber for combustion, with a portion of the combustion products used for heating within the pyrolysis furnace and the remainder sent to a heat exchanger. Magnesite is fed into a calcination furnace for high-temperature smelting, producing carbon dioxide and magnesium oxide. The high-temperature carbon dioxide gas discharged from the calcination furnace is used for drying and preheating the magnesite; a portion of the cooled carbon dioxide is recovered, another portion is fed back into the biomass pyrolysis furnace to react with the biochar, and the remaining portion is fed into the heat exchanger for further temperature enhancement before entering the calcination furnace. This invention achieves the combined production of lightly calcined magnesium oxide, carbon dioxide capture and the production of high-value-added porous biochar, and high-purity carbon dioxide products. It utilizes biomass fuel, a "zero-carbon" energy source, to replace traditional fossil fuels, achieving low-carbon or even zero-carbon production in the initial magnesite smelting process.

Description

Technical Field

[0001] This invention belongs to the field of magnesium-carbon preparation technology, specifically relating to a method and system for the combined production of biomass pyrolysis and synergistic calcination of magnesite. Background Technology

[0002] Biomass pyrolysis is the process of converting volatile or combustible components of biomass feedstock into combustible gases (mainly hydrogen, carbon monoxide, and methane) under high-temperature conditions. Biomass pyrolysis can treat biomass waste and obtain corresponding combustible gases, while also reducing the environmental pollution caused by biomass waste treatment. In the preparation of magnesium oxide, magnesite calcination is used. During magnesite calcination, high-temperature carbon dioxide gas is released. Because of the high temperature of carbon dioxide, it is generally cooled and then recovered, resulting in a waste of the heat in the high-temperature carbon dioxide gas.

[0003] Currently, biomass pyrolysis and magnesium oxide calcination are operated separately and independently. No system or method has been found to combine biomass gas with magnesium oxide calcination for co-production to obtain magnesium carbon. Therefore, further research and development are needed on how to combine biomass pyrolysis and magnesite pyrolysis and how to save energy and reduce consumption. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide an energy-saving and consumption-reducing method and system for the combined production of biomass pyrolysis and magnesite calcination.

[0005] The technical solution for implementing the present invention is as follows:

[0006] A method for co-producing multiple products by biomass pyrolysis coupled with magnesite calcination includes the following steps:

[0007] Biomass feedstock is fed into a biomass pyrolysis furnace, where it is pyrolyzed to produce biochar and biogas.

[0008] The biomass gas discharged from the biomass pyrolysis furnace is sent into the combustion chamber for combustion. Part of the combustion products are sent into the biomass pyrolysis furnace for heating, and the other part is sent into the heat exchanger.

[0009] The magnesite is dried and preheated to a temperature above 400℃;

[0010] After drying and preheating, the magnesite is fed into a calcining furnace, where it decomposes to produce carbon dioxide and magnesium oxide. The magnesium oxide is then cooled by heat exchange and fed into a silo to obtain magnesium oxide.

[0011] The high-temperature carbon dioxide gas discharged from the calcining furnace is used for drying and preheating magnesite. After cooling, part of the high-temperature carbon dioxide gas is recovered, part is sent to the biomass pyrolysis furnace to react with biochar to produce carbon monoxide and porous biochar, and another part enters the heat exchanger to raise the temperature to above 1000℃. After the temperature is raised, it is passed into the calcining furnace for calcining and smelting magnesite.

[0012] In one embodiment of this application: air is used to exchange heat and cool the magnesium oxide discharged from the calcining furnace, and the heated air is then introduced into the combustion chamber to assist combustion and realize the recovery and utilization of waste heat.

[0013] In one embodiment of this application: before the biomass raw material is fed into the biomass pyrolysis furnace, the biomass raw material is screened and crushed to a suitable particle size, dried using a drying device, and fed into the biomass pyrolysis furnace through an automatic feeding mechanism;

[0014] The biomass feedstock is dried using combustion products discharged from the combustion chamber and passing through a heat exchanger.

[0015] Another objective of this invention is to provide a biomass pyrolysis coupled with magnesite calcination co-production system, comprising a biomass feed system, a magnesite feed system, a biomass pyrolysis furnace, a combustion chamber, a calcination furnace, a high-temperature heat exchange device, and a powder heat exchange device;

[0016] The receiving end of the biomass feed system is used to receive biomass feed, and the feeding end of the biomass feed system is connected to the top of the biomass pyrolysis furnace.

[0017] The gas exhaust end of the biomass pyrolysis furnace is connected to the interior of the combustion chamber;

[0018] The flue gas exhaust end of the combustion chamber is connected to a first exhaust pipe and a second exhaust pipe. The first exhaust pipe is connected to the biomass pyrolysis furnace, and the second exhaust pipe is connected to the primary side inlet of the high-temperature heat exchange device.

[0019] The receiving end of the magnesite feeding system is used to receive magnesite, and the feeding end of the magnesite feeding system is connected to the feeding end of the calcining furnace.

[0020] The calcining furnace is connected to a magnesium oxide powder discharge pipe, which is connected to a powder heat exchange device.

[0021] The calcining furnace is connected to a carbon dioxide gas discharge pipe, which is connected to the magnesite feeding system. The carbon dioxide gas discharged from the calcining furnace provides drying and preheating for the magnesite fed into the calcining furnace.

[0022] In one embodiment of this application: the primary side outlet of the high-temperature heat exchanger is connected to the biomass raw material feeding system; the secondary side inlet of the high-temperature heat exchanger is connected to the exhaust end of the magnesite feeding system; and the secondary side outlet of the high-temperature heat exchanger is connected to the calcining furnace.

[0023] In one embodiment of this application, it further includes a first multi-channel valve and a second multi-channel valve;

[0024] The exhaust end of the magnesite feeding system and the secondary side inlet of the high-temperature heat exchanger are connected to the first multi-channel valve, and the first multi-channel valve and the second multi-channel valve are connected by a first connecting pipe.

[0025] The second multi-channel valve is connected to a second connecting pipe and a carbon dioxide recovery pipe, and the second connecting pipe is connected to the inside of the biomass pyrolysis furnace.

[0026] In one embodiment of this application: the discharge end of the calcining furnace is connected to a gas-solid separation device, the gas discharge pipe of the gas-solid separation device serves as a carbon dioxide gas discharge pipe, and the solid discharge pipe of the gas-solid separation device serves as a magnesium oxide powder discharge pipe; the magnesium oxide powder discharge pipe is connected to the primary side inlet of the powder heat exchanger, and the primary side outlet of the powder heat exchanger serves as the magnesium oxide discharge end; the secondary side inlet of the powder heat exchanger is connected to an air inlet pipe, and the secondary side outlet of the powder heat exchanger is connected to the combustion chamber.

[0027] The biomass feed system includes a screening machine, a crusher, biomass feed drying equipment, and a smoke exhaust system;

[0028] The feed end of the screening machine supplies biomass raw materials, the screening discharge end of the screening machine is connected to the inlet end of the biomass raw material drying equipment, the screening discharge end of the screening machine is connected to the feed end of the crusher, the discharge end of the crusher is connected to the feed end of the screening machine, and the discharge end of the biomass raw material drying equipment is connected to the top of the biomass pyrolysis furnace; the primary side outlet of the high-temperature heat exchanger is connected to the air inlet end of the biomass raw material drying equipment, and the air outlet end of the biomass raw material drying equipment is connected to the exhaust device.

[0029] In one embodiment of this application: the magnesite feeding system includes a magnesite drying device, a cyclone separator, a preheating device, a bag filter dust collector, a dewatering device, and a first induced draft fan;

[0030] The inlet of the magnesite drying device is the magnesite feeding end. The material outlet of the magnesite drying device is connected to the material inlet of the cyclone separator. The material outlet of the cyclone separator is connected to the material inlet of the preheating device. The material outlet of the preheating device is connected to the inlet of the calcining furnace.

[0031] The separation outlet of the cyclone separator is connected to the material inlet of the bag filter, the material outlet of the bag filter is connected to the material inlet of the preheating device, the gas discharge pipe of the gas-solid separation device is connected to the material inlet of the preheating device, and the gas discharge end of the preheating device is connected to the drying device.

[0032] The gas discharge end of the bag filter is connected to the inlet end of the dehydration device, the outlet end of the dehydration device is connected to the first induced draft fan, and the first induced draft fan is connected to the first multi-channel valve.

[0033] In one embodiment of this application, the device further includes a biomass gas treatment device and a second induced draft fan. The gas discharge end of the biomass pyrolysis furnace is connected to the inlet end of the biomass gas treatment device, the discharge end of the biomass gas treatment device is connected to the second induced draft fan, and the second induced draft fan is connected to the combustion chamber.

[0034] This invention relates to biomass energy applications and the production of lightly calcined magnesite, specifically proposing a magnesite calcination process based on a biomass pyrolysis device and a carbon dioxide self-circulation system. The main process involves pyrolyzing and carbonizing biomass raw materials to obtain biomass gas and biochar. The biomass gas provides heat for magnesite calcination, while the biochar can be sold as a byproduct or react with carbon dioxide produced from magnesite decomposition at high temperatures to generate carbon monoxide fuel gas and porous biochar. Utilizing the characteristic of carbon dioxide gas produced during magnesite decomposition, a carbon dioxide self-circulation system is constructed using carbon dioxide as a circulating heat carrier: after being heated to a suitable temperature by the biomass gas combustion flue gas through a heat exchanger, the carbon dioxide is used for magnesite calcination, naturally creating a high-concentration carbon dioxide environment within the system. This design can directly separate high-concentration carbon dioxide gas without additional enrichment devices; this gas can react with biochar or be sold as a byproduct. This invention is based on a carbon dioxide self-circulation process to achieve the combined production of lightly burned magnesia, carbon dioxide capture and generation of high-value-added porous biochar, and high-purity carbon dioxide products. At the same time, it uses biomass fuel, a "zero-carbon" energy source, to replace traditional fossil energy, thereby achieving low-carbon or even zero-carbon magnesite smelting in the initial smelting process. This aligns with the green, low-carbon, energy-saving, and efficient development trend of the metallurgical industry.

[0035] This invention utilizes the characteristic that magnesite decomposition only produces carbon dioxide gas. It employs a carbon dioxide self-circulation method to calcine magnesite, recovering high-purity carbon dioxide gas without the need for a carbon dioxide enrichment device. Simultaneously, by combining it with biomass energy, it achieves the co-production of "magnesium oxide-carbon dioxide-biochar".

[0036] This invention utilizes biomass fuel, which is renewable in nature, to partially or completely replace traditional fossil fuels in the magnesite industry, thereby reducing carbon emissions from the fuel end.

[0037] The carbon dioxide gas circulating in this magnesite calcination system can be directly recovered, or it can participate in the reaction in the pyrolysis furnace to produce carbon monoxide gaseous fuel and porous biochar products according to production needs, thus improving the system's ability to dynamically adjust according to production needs.

[0038] This invention can be implemented by making certain engineering modifications to existing light-burned magnesium oxide production equipment, and is suitable for enterprises with energy conservation and emission reduction needs.

[0039] This invention can further combine the processes of biochar and biogas utilization to expand the product range of the production line.

[0040] This invention minimizes environmental harm during the energy conversion process of biomass pyrolysis technology, and produces combustion exhaust gas with low dust, low nitrogen, and low sulfur content, making it more environmentally friendly than the producer gas currently used in the production of light-burned magnesium oxide. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the system flow of the present invention;

[0042] Figure 2 This is a schematic diagram of the system of the present invention;

[0043] In the attached diagram: 1. Screening machine; 2. Crusher; 3. Biomass raw material drying equipment; 4. Biomass pyrolysis furnace; 5. Biomass gas treatment device; 6. Exhaust fan; 7. Combustion chamber; 8. High-temperature heat exchange device; 9. Smoke exhaust device; 10. Magnesite drying device; 11. Cyclone separator; 12. Bag filter dust collector; 13. Magnesite preheating device; 14. Magnesite calcining furnace; 15. Gas-solid separation device; 16. Powder heat exchange device; 17. Dehydration device; 18. Exhaust fan; 19. First multi-channel valve; 20. Second multi-channel valve. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the description, claims and foregoing drawings of this application are intended to cover non-exclusive inclusion.

[0046] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0047] Please see Figure 1 As shown, a method for co-producing biomass through pyrolysis coupled with magnesite calcination includes the following steps:

[0048] Biomass feedstock is fed into a biomass pyrolysis furnace, where it is pyrolyzed to produce biochar and biogas. The biochar obtained from pyrolysis can be sold externally or left in the furnace to react with carbon dioxide to produce carbon monoxide and porous biochar. The resulting biogas can be used as combustion gas. By continuously adding biomass feedstock to the biomass pyrolysis furnace, a continuous supply of pyrolysis products—biochar and biogas—is obtained, providing a combustion gas source for the cogeneration system.

[0049] Biomass gas discharged from the biomass pyrolysis furnace is sent into the combustion chamber for combustion, replacing natural gas or coal gas, so that the combustion chamber is heated. Part of the combustion products obtained in the combustion chamber are sent into the biomass pyrolysis furnace to provide heat energy for the pyrolysis of biomass, and the other part is sent into the heat exchanger to exchange heat with another fluid medium introduced into the heat exchanger. The main combustion product is the high-temperature flue gas emitted.

[0050] The magnesite is dried and preheated to above 400°C so that the magnesite that enters the calcining furnace has a certain temperature, thereby reducing the heat energy consumption in the calcining furnace.

[0051] After drying and preheating, the magnesite is fed into a calcining furnace, where it decomposes to produce carbon dioxide and magnesium oxide. The magnesium oxide is cooled by heat exchange and then fed into a silo to obtain magnesium oxide product. The carbon dioxide gas produced during calcination has a high temperature and is recycled into the co-production system.

[0052] The high-temperature carbon dioxide gas discharged from the calcining furnace is used for drying and preheating magnesite. A portion of the cooled high-temperature carbon dioxide gas is recovered and sent to a biomass pyrolysis furnace as a gasifying agent to react with the char in the biomass to produce combustible carbon monoxide and porous biochar. Another portion is sent to the biomass pyrolysis furnace to react with the biochar, and yet another portion enters a heat exchanger to raise the temperature to above 1000℃. After this temperature increase, it is fed into the calcining furnace for calcining and smelting the magnesite. By recycling the high-temperature carbon dioxide gas discharged from the calcining furnace, the energy consumption of other heat sources in the cogeneration system is reduced.

[0053] Air is used to exchange heat and cool the magnesium oxide discharged from the calcination furnace. The heated air is then introduced into the combustion chamber to aid combustion. The magnesium oxide product discharged from the calcination furnace has a high temperature. To accelerate its cooling, air cooling is used to cool the magnesium oxide product. The air used to cool the magnesium oxide product has a higher temperature and is then introduced into the combustion chamber to aid combustion and recover waste heat.

[0054] Before being fed into the biomass pyrolysis furnace, the biomass feedstock is screened and crushed to a suitable particle size, dried using drying equipment, and then fed into the biomass pyrolysis furnace via an automatic feeding mechanism. The biomass feedstock is dried using combustion products discharged from the combustion chamber and passing through a heat exchanger. The screening process retains biomass feedstock with suitable particle sizes, while larger particles are crushed to reduce their size, and then screened again, repeating this process continuously to obtain biomass feedstock of the appropriate particle size, ensuring the stability of pyrolysis in the biomass pyrolysis furnace.

[0055] The magnesium-carbon co-production method of this invention mainly involves the coordinated operation of biomass pyrolysis and magnesite pyrolysis to achieve the co-production of magnesium oxide, biochar, and carbon dioxide. The biomass pyrolysis process involves screening and crushing the biomass raw material to a suitable particle size, followed by dehydration in a drying device, and then feeding it into a biomass pyrolysis furnace via a feeding mechanism. In the pyrolysis furnace, the biomass raw material undergoes high-temperature pyrolysis to generate biochar and biogas. The obtained biochar can be sold externally or further reacted with carbon dioxide in the pyrolysis furnace to produce carbon monoxide and porous biochar products. The biogas generated in the biomass pyrolysis furnace is sent to a combustion chamber for combustion. Part of the combustion products are used for heating in the pyrolysis furnace, while another part is sent to a heat exchanger to add carbon dioxide circulating gas. After heating the carbon dioxide circulating gas, this portion of the flue gas can be used for further drying and preheating of the biomass raw material, realizing waste heat utilization of the flue gas. Finally, after treatment, it is discharged into the environment. Magnesite calcination and smelting process: Magnesite is fed into a drying and preheating device via a feeding device to dehydrate and preheat to a certain temperature. The preheated magnesite is then fed into a calcining furnace where it is heated by circulating carbon dioxide gas and decomposes to produce new carbon dioxide and magnesium oxide. The resulting magnesium oxide is cooled by air through a heat exchanger and then sent to a silo, while the heated air is sent to the combustion chamber for combustion, thus utilizing the waste heat of the magnesium oxide product. The high-temperature carbon dioxide gas discharged from the calcining furnace is used for drying and preheating the magnesite. After cooling, part of the carbon dioxide is directly recovered, part is used in a pyrolysis furnace to react with biochar, and the remainder is used as a circulating working fluid in a heat exchanger to be heated to a suitable temperature before being fed back into the calcining furnace for calcining the magnesite.

[0056] Please see Figure 2 As shown, a biomass pyrolysis coupled with magnesite calcination co-production system includes a biomass feed system, a magnesite feed system, a biomass pyrolysis furnace 4, a combustion chamber 7, a calcination furnace 14, a high-temperature heat exchange device 8, and a powder heat exchange device 16.

[0057] The receiving end of the biomass feed system is used to receive biomass raw materials and perform screening, crushing, drying and other processing on the biomass raw materials. The feeding end of the biomass feed system is connected to the top of the biomass pyrolysis furnace 4. The biomass raw materials are fed into the biomass pyrolysis furnace 4 and pyrolyzed in the biomass pyrolysis furnace 4.

[0058] The biochar produced in the biomass pyrolysis furnace 4 is discharged from the bottom of the biomass pyrolysis furnace 4. The gas discharge end at the top of the biomass pyrolysis furnace 4 is connected to the inside of the combustion chamber 7, and the generated gas can enter the inside of the combustion chamber 7 for combustion.

[0059] The flue gas discharge end of the combustion chamber 7 is connected to a first exhaust pipe and a second exhaust pipe. The first exhaust pipe is connected to the biomass pyrolysis furnace 4. The flue gas discharged from the combustion chamber 7 can enter the biomass pyrolysis furnace 4 through the first exhaust pipe to provide heat for the pyrolysis of biomass raw materials. The second exhaust pipe is connected to the primary side inlet of the high-temperature heat exchange device 8 to exchange heat with the medium passing through the secondary side of the high-temperature heat exchange device 8 and raise its temperature.

[0060] The receiving end of the magnesite feeding system is used to receive magnesite and dry and preheat it. The feeding end of the magnesite feeding system is connected to the feeding end of the calcining furnace 14, that is, the dried and preheated magnesite can be fed into the calcining furnace 14 for calcination.

[0061] The magnesium oxide is decomposed into carbon dioxide and magnesium oxide at high temperature in the calcining furnace 14. The calcining furnace 14 is connected to a magnesium oxide powder discharge pipe to discharge the magnesium oxide produced in the calcining furnace 14. The magnesium oxide powder discharge pipe is connected to the powder heat exchange device 16. The discharged magnesium oxide is at high temperature and is introduced into the powder heat exchange device 16 to exchange the heat for waste heat utilization. It can also accelerate the temperature reduction of magnesium oxide, making it easier to discharge and store.

[0062] The calcining furnace 14 is connected to a carbon dioxide gas exhaust pipe, which is connected to the magnesite feeding system. The carbon dioxide gas discharged from the calcining furnace 14 provides drying and preheating for the magnesite ore fed into the calcining furnace 14. In other words, the heat generated by the carbon dioxide gas in the calcining furnace 14 is utilized. After the high-temperature carbon dioxide gas is discharged, it is sent to the magnesite feeding system to dry and preheat the magnesite ore material fed into the calcining furnace, increasing the temperature entering the calcining furnace and reducing the energy consumption of the calcining furnace.

[0063] The high-temperature heat exchanger 8 is connected to the biomass feed system via its primary outlet. The high-temperature flue gas passing through the primary outlet of the high-temperature heat exchanger 8 is reused by being introduced into the biomass feed system to dry the biomass, reducing energy consumption. The secondary outlet of the high-temperature heat exchanger 8 is connected to the exhaust outlet of the magnesite feed system, and its secondary outlet is connected to the calcining furnace 14. The circulating carbon dioxide gas, after its temperature decreases in the magnesite feed system, exchanges heat with the high-temperature flue gas in the high-temperature heat exchanger 8, increasing its temperature, and can then be reintroduced into the calcining furnace for use.

[0064] This cogeneration system also includes a first multi-channel valve 19 and a second multi-channel valve 20. The exhaust end of the magnesite feeding system and the secondary side inlet of the high-temperature heat exchanger 8 are connected to the first multi-channel valve 19. A first connecting pipe connects the first multi-channel valve 19 and the second multi-channel valve 20. The second multi-channel valve 20 is connected to a second connecting pipe and a carbon dioxide recovery pipe. The second connecting pipe is connected to the interior of the biomass pyrolysis furnace 4. By setting the first and second multi-channel valves, the gas flow path in the pipes can be adjusted as needed.

[0065] For example, when the production capacity of light-burned magnesia decreases, the heat required by the magnesite calciner 14 decreases. This can be mitigated by reducing the flow rate of carbon dioxide gas supplied to the high-temperature heat exchanger 8 via the first multi-channel valve 19, thereby reducing the flow rate and heat of the carbon dioxide circulating gas supplied to the magnesite calcination system. Excess carbon dioxide is controlled for external discharge and collection via the second multi-channel valve 20, or it can be introduced into the biomass pyrolysis furnace 4 to adjust the temperature and react with the biomass char. The specific ratio is adjusted according to the production capacity of the biomass pyrolysis furnace 4.

[0066] Since the amount of carbon dioxide circulating gas that needs to be heated in the high-temperature heat exchanger 8 is reduced, the heat required by the device is reduced. The output of biomass gas can be reduced by reducing the amount of biomass raw materials fed into the biomass, or by adjusting the second multi-channel valve 20 to reduce the amount of carbon dioxide gas introduced into the biomass pyrolysis furnace 4, thereby inhibiting the reaction of biomass char to carbon monoxide and reducing the total amount of biomass gas.

[0067] A gas-solid separator 15 is connected to the discharge end of the calcining furnace 14. This separator separates the gas-solid mixture discharged from the furnace, specifically separating the magnesium oxide and carbon dioxide gases produced within the furnace. Specifically, the gas discharge pipe of the gas-solid separator 15 serves as the carbon dioxide discharge pipe, and the solid discharge pipe serves as the magnesium oxide powder discharge pipe. The magnesium oxide powder discharge pipe is connected to the primary inlet of the powder heat exchanger 16, and the primary outlet of the powder heat exchanger 16 serves as the magnesium oxide discharge end. The secondary inlet of the powder heat exchanger 16 is connected to an air inlet pipe, and the secondary outlet of the powder heat exchanger 16 is connected to the combustion chamber 7. The air temperature is increased by the powder heat exchanger 16 and then sent to the combustion chamber 7 for combustion.

[0068] The biomass feed system includes a screening machine 1, a crusher 2, a biomass dryer 3, and a flue gas exhaust system 9. The feed end of the screening machine 1 receives the biomass feed, and its screening discharge end is connected to the feed end of the biomass dryer 3. The screening discharge end of the screening machine 1 is connected to the feed end of the crusher 2, and the discharge end of the crusher 2 is connected to the feed end of the screening machine 1. The discharge end of the biomass dryer 3 is connected to the top of the biomass pyrolysis furnace 4. The primary side outlet of the high-temperature heat exchanger 8 is connected to the air inlet of the biomass dryer 3, and the air outlet of the biomass dryer 3 is connected to the flue gas exhaust system 9. Biomass feed of suitable particle size obtained after screening is fed into the biomass dryer for drying and then into the biomass pyrolysis furnace 4. Larger particles of biomass feed that have passed screening are crushed and then screened again, with the screening and crushing cycle repeating. The biomass dryer 3 operates at a drying temperature of 100~250 ℃.

[0069] The magnesite feeding system includes a magnesite drying device 10, a cyclone separator 11, a preheating device 13, a bag filter 12, a dewatering device 17, and a first induced draft fan 18. The inlet of the magnesite drying device 10 is the magnesite feed end; the material outlet of the magnesite drying device is connected to the material inlet of the cyclone separator 11; the material outlet of the cyclone separator 11 is connected to the material inlet of the preheating device; and the material outlet of the preheating device 13 is connected to the inlet of the calcining furnace 14. The separation outlet of the cyclone separator 11 is connected to the bag filter 12. The material inlet of the bag filter 12 is connected to the material outlet of the bag filter 12, which is connected to the material inlet of the preheating device 13. The gas outlet of the gas-solid separation device 15 is connected to the material inlet of the preheating device 13, and the gas outlet of the preheating device 13 is connected to the drying device. The magnesite is first dried by the drying device, and then sent to the cyclone separator to separate the gas and solid. The mixture is then filtered by the bag filter to remove the magnesite from the gas-solid mixture and sent to the preheating device.

[0070] Among them, for the magnesite calcination system, different particle sizes of magnesite raw materials are used depending on the different magnesite calcination furnaces 14: for powder calcination equipment such as dynamic calcination furnaces, the particle size of dried magnesite is usually distributed in the range of 0.1 to several hundred micrometers; for equipment such as rotary kilns and vertical furnaces, the particle size of magnesite is usually distributed in the range of 1 to 10 centimeters.

[0071] In this system, the gas discharge end of the bag filter 12 is connected to the inlet end of the dehydration device 17 to reduce the moisture content in the gas. The outlet end of the dehydration device 17 is connected to the first induced draft fan 18, which is connected to the first multi-channel valve 19. The first induced draft fan 18 provides the gas flow power in the magnesite feeding system.

[0072] The magnesite co-production system of this invention also includes a biomass gas treatment device 5 and a second induced draft fan 6. The gas discharge end of the biomass pyrolysis furnace 4 is connected to the inlet end of the biomass gas treatment device 5, and the discharge end of the biomass gas treatment device 5 is connected to the second induced draft fan 6. The second induced draft fan is connected to the combustion chamber 7. The flue gas discharged from the biomass pyrolysis furnace 4 is purified by the biomass gas treatment device 5.

[0073] The working process of the magnesite co-production system of this invention is as follows: Biomass raw materials are fed into screening machine 1 via conveyor belts or similar conveying devices. Raw materials that meet the particle size requirements are sent to raw material drying equipment 3, while raw materials that do not meet the particle size requirements are sent to crusher 2 for further crushing and then sent back to screening machine 1 for screening. After being dried by the biomass raw material drying equipment, the biomass raw materials are fed into pyrolysis furnace 4 from the top by hoppers or conveyor belts, and the pyrolysis and other reaction processes are completed in the furnace. The generated biochar is discharged from the bottom of pyrolysis furnace 4, and the biomass gas is discharged from the gas outlet at the top of pyrolysis furnace 4 and enters the gas treatment device 5. The purified biomass gas enters the combustion chamber 7 for combustion under the traction of the second induced draft fan 6. Part of the flue gas generated by combustion enters pyrolysis furnace 4 to provide heat for the pyrolysis of biomass raw materials, and the other part enters high-temperature heat exchange device 8 to heat the circulating carbon dioxide gas from the magnesite calcination system. The flue gas after heat exchange is passed into drying equipment 3 to dry the biomass raw materials, and finally discharged into the environment through exhaust device 9.

[0074] Magnesite raw material enters the magnesite drying unit 10 via a feeding device for dehydration, and then passes through a cyclone separator 11 and a bag filter 12 for gas-solid separation. The separated magnesite is sent to a preheating unit 13 for preheating, and then sent to a calcining furnace 14 for decomposition, producing carbon dioxide and magnesium oxide. The product carbon dioxide gas and magnesium oxide are separated by a gas-solid separation unit 15. The product magnesium oxide enters a powder heat exchanger 16 for cooling, and the sensible heat it carries is recovered by air. The heated air is then sent to the combustion chamber 7 for combustion. The carbon dioxide gas separated by the gas-solid separation unit 15 enters the magnesite preheating unit 13 and the magnesite drying unit 10 for drying and preheating the magnesite raw material. The cooled carbon dioxide gas passes through a cyclone separator 11 and a bag filter 12 to reduce particulate matter content, and then passes through a dehydration unit 17 to remove water vapor from the gas for recycling or recovery. The entire process of the carbon dioxide gas is completed under the traction of the first induced draft fan 18. The carbon dioxide gas passing through the first induced draft fan 18 is diverted through valve 19. Part of it enters the high-temperature heat exchanger 8, is heated to a suitable temperature, and is then sent back to the calcining furnace 14. The other part is further diverted through valve 20. Of the carbon dioxide gas diverted through valve 20, part can be directly recovered for sale or subsequent production processes, while the other part can be returned to the pyrolysis furnace 4 to participate in the biochar reaction, depending on production needs.

[0075] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit them, much less limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields is similarly included within the patent protection scope of the present invention.

Claims

1. A method for co-producing biomass through pyrolysis coupled with magnesite calcination, characterized in that, Includes the following steps: Biomass feedstock is fed into a biomass pyrolysis furnace, where it is pyrolyzed to produce biochar and biogas. Biomass gas discharged from the biomass pyrolysis furnace is sent into the combustion chamber for combustion. Part of the combustion products are sent into the biomass pyrolysis furnace for heating, and the other part is sent into the high-temperature heat exchange device. The magnesite is dried and preheated to a temperature above 400℃; After drying and preheating, the magnesite is fed into a calcining furnace, where it decomposes to produce carbon dioxide and magnesium oxide. The magnesium oxide is then cooled by heat exchange and fed into a silo to obtain magnesium oxide. The high-temperature carbon dioxide gas discharged from the calcining furnace is used for drying and preheating magnesite. After cooling, part of the high-temperature carbon dioxide gas is recovered, part is sent to the biomass pyrolysis furnace to react with biochar to produce carbon monoxide and porous biochar, and another part enters the high-temperature heat exchange device to raise the temperature to more than 1000℃. After the temperature is raised, it is passed into the calcining furnace for calcining and smelting magnesite.

2. The method for co-producing biomass through pyrolysis coupled with magnesite calcination as described in claim 1, characterized in that, Air is used to exchange heat and cool the magnesium oxide discharged from the calcining furnace. The heated air is then introduced into the combustion chamber to aid combustion and recover waste heat.

3. The method for co-producing multiple products by biomass pyrolysis coupled with magnesite calcination as described in claim 1, characterized in that, Before the biomass raw materials are fed into the biomass pyrolysis furnace, the biomass raw materials are screened and crushed to a suitable particle size, dried using drying equipment, and then fed into the biomass pyrolysis furnace through an automatic feeding mechanism. The biomass feedstock is dried using combustion products that are discharged from the combustion chamber and pass through a high-temperature heat exchanger.

4. A biomass pyrolysis coupled with magnesite calcination co-production system employing the polygeneration method described in any one of claims 1-3, characterized in that, It includes a biomass feed system, a magnesite feed system, a biomass pyrolysis furnace, a combustion chamber, a calcining furnace, a high-temperature heat exchange device, and a powder heat exchange device; The receiving end of the biomass feed system is used to receive biomass feed, and the feeding end of the biomass feed system is connected to the top of the biomass pyrolysis furnace. The gas exhaust end of the biomass pyrolysis furnace is connected to the interior of the combustion chamber; The flue gas exhaust end of the combustion chamber is connected to a first exhaust pipe and a second exhaust pipe. The first exhaust pipe is connected to the biomass pyrolysis furnace, and the second exhaust pipe is connected to the primary side inlet of the high-temperature heat exchange device. The receiving end of the magnesite feeding system is used to receive magnesite, and the feeding end of the magnesite feeding system is connected to the feeding end of the calcining furnace. The calcining furnace is connected to a magnesium oxide powder discharge pipe, which is connected to a powder heat exchange device. The calcining furnace is connected to a carbon dioxide gas discharge pipe, which is connected to the magnesite feeding system. The carbon dioxide gas discharged from the calcining furnace provides drying and preheating for the magnesite fed into the calcining furnace. The primary side outlet of the high-temperature heat exchanger is connected to the biomass raw material feeding system; the secondary side inlet of the high-temperature heat exchanger is connected to the exhaust end of the magnesite feeding system; and the secondary side outlet of the high-temperature heat exchanger is connected to the calcining furnace. It also includes a first multi-channel valve and a second multi-channel valve; The exhaust end of the magnesite feeding system and the secondary side inlet of the high-temperature heat exchanger are connected to the first multi-channel valve, and the first multi-channel valve and the second multi-channel valve are connected by a first connecting pipe. The second multi-channel valve is connected to a second connecting pipe and a carbon dioxide recovery pipe, and the second connecting pipe is connected to the inside of the biomass pyrolysis furnace.

5. The biomass pyrolysis coupled with magnesite calcination co-production system as described in claim 4, characterized in that, The calcining furnace is connected to a gas-solid separation device at its discharge end. The gas discharge pipe of the gas-solid separation device serves as a carbon dioxide gas discharge pipe, and the solid discharge pipe of the gas-solid separation device serves as a magnesium oxide powder discharge pipe. The magnesium oxide powder discharge pipe is connected to the primary side inlet of the powder heat exchanger, and the primary side outlet of the powder heat exchanger serves as the magnesium oxide discharge end. The secondary side inlet of the powder heat exchanger is connected to an air inlet pipe, and the secondary side outlet of the powder heat exchanger is connected to the combustion chamber.

6. The biomass pyrolysis coupled with magnesite calcination co-production system as described in claim 4, characterized in that, The biomass feed system includes a screening machine, a crusher, biomass feed drying equipment, and a smoke exhaust system; The feed end of the screening machine supplies biomass raw materials, the screening discharge end of the screening machine is connected to the inlet end of the biomass raw material drying equipment, the screening discharge end of the screening machine is connected to the feed end of the crusher, the discharge end of the crusher is connected to the feed end of the screening machine, and the discharge end of the biomass raw material drying equipment is connected to the top of the biomass pyrolysis furnace; the primary side outlet of the high-temperature heat exchanger is connected to the air inlet end of the biomass raw material drying equipment, and the air outlet end of the biomass raw material drying equipment is connected to the exhaust device.

7. A biomass pyrolysis coupled with magnesite calcination co-production system as described in claim 5, characterized in that, The magnesite feeding system includes a magnesite drying unit, a cyclone separator, a preheating unit, a bag filter dust collector, a dewatering unit, and a first induced draft fan; The inlet of the magnesite drying device is the magnesite feeding end. The material outlet of the magnesite drying device is connected to the material inlet of the cyclone separator. The material outlet of the cyclone separator is connected to the material inlet of the preheating device. The material outlet of the preheating device is connected to the inlet of the calcining furnace. The separation outlet of the cyclone separator is connected to the material inlet of the bag filter, the material outlet of the bag filter is connected to the material inlet of the preheating device, the gas discharge pipe of the gas-solid separation device is connected to the material inlet of the preheating device, and the gas discharge end of the preheating device is connected to the drying device. The gas discharge end of the bag filter is connected to the inlet end of the dehydration device, the outlet end of the dehydration device is connected to the first induced draft fan, and the first induced draft fan is connected to the first multi-channel valve.

8. A biomass pyrolysis coupled with magnesite calcination co-production system as described in claim 4, characterized in that, It also includes a biomass gas treatment device and a second induced draft fan. The gas discharge end of the biomass pyrolysis furnace is connected to the inlet end of the biomass gas treatment device, the discharge end of the biomass gas treatment device is connected to the second induced draft fan, and the second induced draft fan is connected to the combustion chamber.

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