Biomass pyrolysis coupling magnesite calcination synergetic poly-generation method and system

Abstract

The invention discloses a biomass pyrolysis coupling magnesite calcination synergetic poly-generation method and system. The method mainly comprises the following steps: pyrolyzing a biomass raw material in a biomass pyrolyzing furnace to generate biomass charcoal and biomass gas; biomass gas is fed into the combustion chamber to be combusted, one part of combustion products are fed into the biomass pyrolyzing furnace to supply heat, and the other part of the combustion products are fed into the heat exchanger; feeding the magnesite into a calcining furnace for high-temperature smelting to generate carbon dioxide and magnesium oxide; high-temperature carbon dioxide gas exhausted by the calcining furnace is used for drying and preheating magnesite, one part of the cooled gas is recycled, one part of the cooled gas is fed into the biomass pyrolyzing furnace to react with biomass charcoal, and the other part of the cooled gas enters the heat exchanger to be heated and then enters the calcining furnace. According to the method, light calcined magnesia and carbon dioxide capture are achieved, joint production of high-added-value multi-aperture biomass charcoal and a high-purity carbon dioxide product is generated, biomass fuel which is zero-carbon energy is used for replacing traditional fossil energy, and low-carbon even zero-carbon carbonization in the initial smelting link of magnesite is achieved.

Description

Technical Field

[0001] The invention belongs to the field of magnesium carbon preparation technology, and specifically relates to a multi-generation method and system for synergistically combining biomass pyrolysis and magnesite calcination. Background Art

[0002] Biomass pyrolysis is the process of converting the volatile or combustible part of biomass raw materials into combustible gases (mainly hydrogen, carbon monoxide and methane) under high temperature conditions. Biomass pyrolysis can be used to treat biomass waste and obtain corresponding combustible gases, which can also reduce the pollution caused by the treatment of biomass waste to the environment. In the preparation process of magnesium oxide, magnesium oxide can be obtained by calcining magnesite. During the calcination of magnesite, high-temperature carbon dioxide gas will be released. Since carbon dioxide gas has a high temperature, it is generally cooled and then recycled, resulting in heat waste in the high-temperature carbon dioxide gas.

[0003] At present, biomass pyrolysis and magnesium oxide calcination are operated separately and independently, and there is no system and method for combining biomass gas with magnesium oxide calcination to obtain magnesium carbon. Therefore, further research and development is needed on the combined use of biomass pyrolysis and dolomite pyrolysis and how to save energy and reduce consumption. Summary of the invention

[0004] In view of the above problems, the object of the present invention is to provide a multi-generation method and system for energy-saving and consumption-reducing biomass pyrolysis coupled with magnesite calcination.

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

[0006] A polygeneration method of biomass pyrolysis coupled with magnesite calcination, comprising the following steps:

[0007] The biomass raw materials are fed into the biomass pyrolysis furnace, and the biomass raw materials are pyrolyzed in the biomass pyrolysis furnace to generate biomass charcoal and biomass gas;

[0008] The biomass gas discharged from the biomass pyrolysis furnace is sent into the combustion chamber for combustion, and part of the combustion product is sent into the biomass pyrolysis furnace for heat supply, and the other part is sent into the heat exchanger;

[0009] Dry and preheat the magnesite to above 400°C;

[0010] The dried and preheated magnesite is sent to the calcining furnace, where it decomposes to produce carbon dioxide and magnesium oxide. The magnesium oxide is cooled by heat exchange and then sent to the silo to obtain magnesium oxide.

[0011] The high-temperature carbon dioxide gas discharged from the calcining furnace is used to dry and preheat the magnesite. Part of the high-temperature carbon dioxide gas after cooling is recovered, part of it is sent to the biomass pyrolysis furnace to react with biochar to produce carbon monoxide and multi-porous biochar, and another part enters the heat exchanger to increase the temperature to more than 1000°C. After the temperature is increased, it is passed into the calcining furnace for calcination and smelting of magnesite.

[0012] In one implementation of the present application: air is used to perform heat exchange cooling on the magnesium oxide discharged from the calcining furnace, and the air heated by heat exchange is introduced into the combustion chamber to assist combustion and realize waste heat recovery and utilization.

[0013] In one implementation of the present 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 raw material is dried using the combustion product discharged from the combustion chamber and passed through the heat exchanger.

[0015] Another object of the present invention is to provide a polygeneration system for biomass pyrolysis coupled with magnesite calcination, including a biomass raw material feeding system, a magnesite feeding 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 raw material feeding system is used to receive the biomass raw material, and the feeding end of the biomass raw material feeding system is connected to the top of the biomass pyrolysis furnace;

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

[0018] The smoke 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 end of the high-temperature heat exchange device;

[0019] The receiving end of the magnesite feeding system is used to receive the 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 pipeline, and the magnesium oxide powder discharge pipeline is connected to a powder heat exchange device;

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

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

[0023] In one implementation of the present application: it also 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 end of the high-temperature heat exchange device are connected to a first multi-channel valve, and a first connecting pipe is connected between the first multi-channel valve and the second multi-channel valve;

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

[0026] In one implementation of the present 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 end of the powder heat exchanger, and the primary side outlet end of the powder heat exchanger serves as the magnesium oxide discharge end; the secondary side inlet end of the powder heat exchanger is connected to the air inlet pipe, and the secondary side outlet end of the powder heat exchanger is connected to the combustion chamber.

[0027] The biomass raw material feeding system includes a screening machine, a crusher, a biomass raw material drying equipment, and a smoke exhaust device;

[0028] The feed end of the screening machine is used for biomass raw materials to enter, the screening discharge end of the screening machine is connected to the feed 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 discharge end of the high-temperature heat exchange device 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 smoke exhaust device.

[0029] In one implementation of the present application: the magnesite feeding system includes a magnesite drying device, a cyclone separator, a preheating device, a bag dust removal device, a dehydration device, and a first induced draft fan;

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

[0031] The separation end of the cyclone separator is connected to the material inlet end of the bag dust removal device, the material outlet end of the bag dust removal device is connected to the material inlet end of the preheating device, the gas discharge pipe of the gas-solid separation device is connected to the material inlet end 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 dust removal device 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 implementation of the present application: it also includes a biomass gas processing device and a second induced draft fan. The gas exhaust end of the biomass pyrolysis furnace is connected to the inlet end of the biomass gas processing device, the exhaust end of the biomass gas processing device is connected to the second induced draft fan, and the second induced draft fan is connected to the combustion chamber.

[0034] The present invention relates to the application of biomass energy and the production of light-burned magnesium oxide, and specifically proposes a set of magnesite calcining processes based on a biomass pyrolysis device and carbon dioxide self-circulation. The main purpose is to pyrolyze and carbonize biomass raw materials to obtain biomass gas and biomass charcoal. Among them, biomass gas is used for heating the calcination of magnesite, and biomass charcoal can be sold as a by-product, or react with carbon dioxide generated by the decomposition of magnesite at high temperature to generate carbon monoxide fuel gas and multi-pore biomass charcoal. Taking advantage of the characteristic that magnesite decomposes to produce carbon dioxide gas, carbon dioxide is used as a circulating heat carrier to construct a carbon dioxide self-circulation system: after carbon dioxide is heated to a suitable temperature by the biomass gas combustion flue gas through a heat exchange device, it is used for the calcination of magnesite, and a high-concentration carbon dioxide environment is naturally formed in the system. This design can directly separate high-concentration carbon dioxide gas without the need for an additional enrichment device. This part of the gas can react with biomass charcoal or be sold as a by-product. The present invention is based on the carbon dioxide self-circulation process to achieve the combined production of light-burned magnesium oxide, carbon dioxide capture and high-value-added multi-porous biochar and high-purity carbon dioxide products. At the same time, the "zero-carbon" energy of biomass fuel is used to replace traditional fossil energy, thereby achieving low-carbon or even zero-carbonization in the initial smelting process of magnesite, which is in line with the development trend of green, low-carbon, energy-saving and high-efficiency in the metallurgical industry.

[0035] The present invention utilizes the characteristic that magnesite decomposition only produces carbon dioxide gas, uses carbon dioxide self-circulation to calcine magnesite, and can recover high-purity carbon dioxide gas without a carbon dioxide enrichment device. At the same time, combined with biomass energy, the co-production of "magnesium oxide-carbon dioxide-biomass charcoal" is realized.

[0036] The present invention utilizes biomass fuel that is recyclable and renewable in nature to partially or completely replace traditional fossil energy in the magnesite industry, thereby reducing carbon emissions from the fuel end.

[0037] The carbon dioxide gas circulating in the magnesite calcining system can be directly recovered, and can also participate in the reaction in the pyrolysis furnace to produce carbon monoxide gas fuel and multi-porous biochar products according to production needs, thereby improving the system's ability to dynamically adjust according to production needs.

[0038] The present invention can be realized by carrying out certain engineering transformation on the basis of existing light-burned magnesium oxide production equipment, and is suitable for enterprises with energy-saving and emission-reduction requirements.

[0039] The present invention can further combine the process of utilizing biochar and biogas to expand the product range of the production line.

[0040] The energy conversion process of biomass pyrolysis technology in the present invention has little harm to the environment, and the combustion tail gas has low dust content, low nitrogen content, and low sulfur content. Compared with the producer gas used in the current light-burned magnesium oxide production, it is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0043] In the attached drawings, 1. screening machine; 2. crusher; 3. biomass raw material drying equipment; 4. biomass pyrolysis furnace; 5. biomass gas processing device; 6. induced draft fan; 7. combustion chamber; 8. high-temperature heat exchange device; 9. smoke exhaust device; 10. magnesite drying device; 11. cyclone separator; 12. bag dust removal device; 13. magnesite preheating device; 14. magnesite calcining furnace; 15. gas-solid separation device; 16. powder heat exchange device; 17. dehydration device; 18. induced draft fan; 19. first multi-channel valve; 20. second multi-channel valve. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

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

[0047] See also Figure 1 As shown, a polygeneration method of biomass pyrolysis coupled with magnesite calcination comprises the following steps:

[0048] The biomass raw materials are fed into the biomass pyrolysis furnace, where they are pyrolyzed to generate biochar and biogas. The biochar obtained by pyrolysis can be sold or left in the pyrolysis furnace to continue to react with carbon dioxide to produce carbon monoxide and multi-porous biochar. The biomass gas obtained can be used as combustion gas. By continuously adding biomass raw materials to the biomass pyrolysis furnace, continuous pyrolysis products: biochar and biogas are obtained, providing a combustion gas source for the cogeneration system.

[0049] The biomass gas discharged from the biomass pyrolysis furnace is sent into the combustion chamber for combustion, replacing natural gas or coal gas for combustion, so that the combustion chamber is heated and the temperature is increased. A part of the combustion products obtained by combustion in the combustion chamber is passed into the biomass pyrolysis furnace for heat supply, providing heat energy for pyrolysis in the biomass pyrolysis furnace, and the other part is sent to the heat exchanger to exchange heat with another fluid medium passed into the heat exchanger, wherein the combustion product is mainly the discharged high-temperature flue gas.

[0050] Dry and preheat the magnesite to above 400°C, so that the magnesite entering the calcining furnace has a certain temperature, reducing the heat energy consumption in the calcining furnace;

[0051] The dried and preheated magnesite is fed into the calcining furnace, where it decomposes to produce carbon dioxide and magnesium oxide. The magnesium oxide is cooled by heat exchange and then fed into the silo to obtain magnesium oxide products. The carbon dioxide gas generated during the calcining process has a relatively high temperature and enters the co-production system for recycling.

[0052] That is, the high-temperature carbon dioxide gas discharged from the calcining furnace is used to dry and preheat the magnesite. A portion of the high-temperature carbon dioxide gas after cooling is recovered and sent to the biomass pyrolysis furnace as a gasifying agent to react with the carbon in the biomass to obtain combustible gas carbon monoxide and multi-porous biomass charcoal. A portion is sent to the biomass pyrolysis furnace to react with the biomass charcoal, and another portion enters the heat exchanger to increase the temperature to more than 1000°C. After the temperature is increased, it is passed into the calcining furnace for calcining and smelting of 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 can be reduced.

[0053] Air is used to cool the magnesium oxide discharged from the calcining furnace by heat exchange, and the air heated by heat exchange is introduced into the combustion chamber to assist combustion. The magnesium oxide product discharged from the calcining furnace has a high temperature. In order to accelerate its cooling, the magnesium oxide product is cooled by air cooling. The temperature of the air used to cool the magnesium oxide product is increased and introduced into the combustion chamber to assist combustion in the combustion chamber and realize waste heat recovery.

[0054] Before the biomass raw materials are fed into the biomass pyrolysis furnace, they are screened and crushed to a suitable particle size, dried by a drying device, and fed into the biomass pyrolysis furnace through an automatic feeding mechanism; the biomass raw materials are dried by the combustion products discharged from the combustion chamber and passed through the heat exchanger. Among them, by screening the biomass raw materials, the raw materials with suitable particle sizes are retained, and the biomass raw materials with large particle sizes are crushed to reduce the particle size, and then screened again, and the process is repeated continuously to obtain biomass raw materials with corresponding particle sizes to ensure the pyrolysis stability in the biomass pyrolysis furnace.

[0055] The magnesium-carbon co-production method of the present invention is mainly to coordinate the pyrolysis of biomass and the pyrolysis of magnesite to achieve the co-production process of magnesium oxide, biochar and carbon dioxide. Among them, the biomass pyrolysis process: after the biomass raw material is screened and crushed to a suitable particle size, it enters the drying device for dehydration, and is sent to the biomass pyrolysis furnace through the feeding mechanism. In the biomass pyrolysis furnace, the biomass raw material is pyrolyzed at high temperature to generate biochar and biomass gas. The obtained biochar can be sold outside, or it can continue to react with carbon dioxide in the pyrolysis furnace to generate carbon monoxide and multi-aperture biochar products. Among them, the biomass gas generated in the biomass pyrolysis furnace is sent to the combustion chamber for combustion, part of the combustion product is passed into the pyrolysis furnace for heating, and the other part of the combustion product is sent to the heat exchanger for adding carbon dioxide circulating gas. After heating the carbon dioxide circulating gas, this part of the flue gas can continue to be used for drying and preheating of the biomass raw material, realizing the waste heat utilization of the flue gas, and finally discharged into the environment after treatment. The calcination and smelting process of magnesite: magnesite is sent to the drying and preheating equipment through the feeding device for dehydration and preheating to a certain temperature. The preheated magnesite is sent to the calcining furnace and heated by the heated circulating carbon dioxide gas to decompose and produce new carbon dioxide and magnesium oxide. The product magnesium oxide is cooled by air through the heat exchange device and sent to the silo, and the heated air is sent to the combustion chamber for combustion, realizing the waste heat utilization of the product magnesium oxide. The high-temperature carbon dioxide gas discharged from the calcining furnace is used for drying and preheating of magnesite. Subsequently, part of the cooled carbon dioxide is directly recovered, part of it can be fed into the pyrolysis furnace to react with biochar, and the remaining part enters the heat exchanger as a circulating working fluid, is heated to a suitable temperature, and then is passed into the calcining furnace for calcining magnesite.

[0056] See also Figure 2 As shown, a polygeneration system for biomass pyrolysis coupled with magnesite calcination, comprising a biomass raw material feeding system, a magnesite feeding 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 raw material feeding system is used to receive the biomass raw material and perform screening, crushing, drying and other processing on the biomass raw material. The feeding end of the biomass raw material feeding system is connected to the top of the biomass pyrolysis furnace 4. The biomass raw material is fed into the biomass pyrolysis furnace 4 and pyrolysis is carried out in the biomass pyrolysis furnace 4.

[0058] The biomass charcoal produced in the biomass pyrolysis furnace 4 is discharged from the discharge end at the bottom of the biomass pyrolysis furnace 4, and 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 combustion chamber 7 for combustion.

[0059] The smoke exhaust end of the combustion chamber 7 is connected to the first exhaust pipe and the second exhaust pipe. The first exhaust pipe is connected to the biomass pyrolysis furnace 4. The smoke exhausted from the combustion chamber 7 can enter the biomass pyrolysis furnace 4 through the first exhaust pipe to provide heat for the pyrolysis of the biomass raw materials. The second exhaust pipe is connected to the primary side inlet end of the high-temperature heat exchange device 8 to perform heat exchange and heat up the medium passing through the secondary side of the high-temperature heat exchange device 8.

[0060] Among them, the receiving end of the magnesite feeding system is used to receive magnesite and dry and preheat the magnesite. 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] In the calcining furnace 14, it is decomposed into carbon dioxide and magnesium oxide at high temperature. The calcining furnace 14 is connected with a magnesium oxide powder discharge pipe for discharging 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 has a high temperature and is passed into the powder heat exchange device 16 to exchange the heat therein for waste heat utilization, and can also accelerate the temperature reduction of the magnesium oxide, which is convenient for discharging and storage.

[0062] The calcining furnace 14 is connected to a carbon dioxide gas exhaust pipeline, 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 fed into the calcining furnace 14. That is, the heat of the carbon dioxide gas generated in the calcining furnace 14 is utilized. After the high-temperature carbon dioxide gas is discharged, it is fed into the magnesite feeding system to dry and preheat the magnesite material fed into the calcining furnace, thereby increasing the temperature entering the calcining furnace and reducing the energy consumption of the calcining furnace.

[0063] Among them, the primary side outlet of the high-temperature heat exchange device 8 is connected to the biomass raw material feeding system, and the high-temperature flue gas after passing through the primary side of the high-temperature heat exchange device 8 is reused, that is, introduced into the biomass raw material feeding system to dry the biomass raw material and reduce energy consumption; the secondary side inlet of the high-temperature heat exchange device 8 is connected to the exhaust end of the magnesite feeding system, and the secondary side outlet of the high-temperature heat exchange device 8 is connected to the calcining furnace 14. The temperature of the circulating carbon dioxide gas passing through the magnesite feeding system is reduced, and after entering the high-temperature heat exchange device 8 and exchanging heat with the high-temperature flue gas, the temperature is increased, and it can be introduced into the calcining furnace for use again.

[0064] The cogeneration system further 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 end of the high-temperature heat exchange device 8 are connected to the first multi-channel valve 19, and a first connecting pipe is connected between 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, and the second connecting pipe is connected to the inside of the biomass pyrolysis furnace 4. By setting the first multi-channel valve and the second multi-channel valve, the gas flow path in the pipeline can be adjusted as needed.

[0065] For example, when the production capacity of light-burned magnesium is reduced, the heat required by the magnesite calcining furnace 14 is reduced, and the flow rate of carbon dioxide gas supplied to the high-temperature heat exchange device 8 can be reduced through the first multi-channel valve 19, thereby reducing the flow rate and heat of the carbon dioxide circulating gas supplied to the magnesite calcining system. The excess carbon dioxide is controlled by the second multi-channel valve 20 for external capture, or is passed into the biomass pyrolysis furnace 4 to adjust the temperature and react with the biomass charcoal. The specific ratio is adjusted according to the production capacity of the biomass pyrolysis furnace 4.

[0066] Since the high-temperature heat exchange device 8 needs to heat less carbon dioxide circulating gas, the device needs less heat, and the output of biomass gas can be reduced by reducing the amount of biomass raw materials fed, or by adjusting the second multi-channel valve 20 to reduce the amount of carbon dioxide gas entering the biomass pyrolysis furnace 4, thereby inhibiting the reaction of biochar being converted into carbon monoxide and reducing the total amount of biomass gas.

[0067] The discharge end of the calcining furnace 14 is connected with a gas-solid separation device 15, which is used to perform gas-solid separation on the gas-solid mixture discharged from the calcining furnace, that is, to separate the magnesium oxide and carbon dioxide gas generated in the calcining furnace. Specifically, the gas discharge pipe of the gas-solid separation device 15 is used as a carbon dioxide gas discharge pipe, and the solid discharge pipe of the gas-solid separation device 15 is used as a magnesium oxide powder discharge pipe; the magnesium oxide powder discharge pipe is connected to the primary side inlet end of the powder heat exchange device 16, and the primary side outlet end of the powder heat exchange device 16 is used as the magnesium oxide discharge end; the secondary side inlet end of the powder heat exchange device 16 is connected to the air inlet pipe, and the secondary side outlet end of the powder heat exchange device 16 is connected to the combustion chamber 7. The temperature of the air is increased by the powder heat exchange device 16, and then sent to the combustion chamber 7 for combustion.

[0068] Among them, the biomass raw material feeding system includes a screening machine 1, a crusher 2, a biomass raw material drying equipment 3, and a smoke exhaust device 9; the feeding end of the screening machine 1 is for biomass raw materials to enter, the screening discharge end of the screening machine 1 is connected to the feeding end of the biomass raw material drying equipment 3, the screening discharge end of the screening machine 1 is connected to the feeding end of the crusher 2, the discharge end of the crusher 2 is connected to the feeding end of the screening machine 1, and the discharge end of the biomass raw material drying equipment 3 is connected to the top of the biomass pyrolysis furnace 4; the primary side discharge end of the high-temperature heat exchange device 8 is connected to the air inlet end of the biomass raw material drying equipment 3, and the air outlet end of the biomass raw material drying equipment 3 is connected to the smoke exhaust device 9. The biomass raw materials with suitable particle size obtained after screening are sent to the biomass raw material drying equipment for drying, and then sent to the biomass pyrolysis furnace 4; the large-particle biomass raw materials screened are screened again after crushing, and the screening and crushing are operated in a cycle. Among them, the biomass raw material drying equipment 3: the drying temperature is 100-250℃.

[0069] The magnesite feeding system includes a magnesite drying device 10, a cyclone separator 11, a preheating device 13, a bag dust removal device 12, a dehydration device 17, and a first induced draft fan 18; the inlet end of the magnesite drying device 10 is the magnesite feeding end, the material outlet end of the magnesite drying equipment is connected to the material inlet end of the cyclone separator 11, the material outlet end of the cyclone separator 11 is connected to the material inlet end of the preheating device, and the material outlet end of the preheating device 13 is connected to the inlet end of the calcining furnace 14; the separation end of the cyclone separator 11 is connected to the bag dust removal device 12, the dehydration device 17, and the first induced draft fan 18; The material inlet of the bag dust removal device 12 is connected, the material outlet of the bag dust removal device 12 is connected to the material inlet of the preheating device 13, the gas discharge pipe of the gas-solid separation device 15 is connected to the material inlet of the preheating device 13, and the gas discharge end of the preheating device 13 is connected to the drying device; the magnesite is first dried by the drying device, and the dried magnesite is sent to the cyclone separator to separate the gas and solid therein, and then filtered by the bag dust removal device, the magnesite in the gas-solid mixture is filtered out and sent to the preheating device.

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

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

[0072] The magnesite co-production system of the present invention further 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, and 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 the present invention is as follows: the biomass raw material is sent into the screening machine 1 through a belt conveyor or other similar conveying device, the raw material that meets the particle size requirement is sent into the raw material drying equipment 3, and the raw material that does not meet the particle size requirement is sent into the crusher 2 to be further crushed and then sent back to the screening machine 1 for screening; the biomass raw material dried by the biomass raw material drying equipment is sent into the pyrolysis furnace 4 from the top by a hopper or a belt conveyor or other equipment, and the pyrolysis and other reaction processes are completed in the furnace, the generated biomass char is discharged from the bottom of the pyrolysis furnace 4, the biomass gas is discharged from the gas outlet at the top of the pyrolysis furnace 4 and enters the gas processing device 5, the purified biomass gas enters the combustion chamber 7 under the traction of the second induced draft fan 6 for combustion, a part of the flue gas generated by the combustion enters the pyrolysis furnace 4 to provide heat for the pyrolysis of the biomass raw material, and the other part enters the 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 the drying equipment 3 to dry the biomass raw material, and finally discharged into the environment through the smoke exhaust device 9.

[0074] The magnesite raw material enters the magnesite drying device 10 through the feeding device for dehydration, and is successively separated by the cyclone separator 11 and the bag dust removal device 12 for gas-solid separation. The separated magnesite is sent to the preheating device 13 for preheating, and then sent to the calcining furnace 14 for decomposition to produce carbon dioxide and magnesium oxide. The product carbon dioxide gas and magnesium oxide are separated by the gas-solid separation device 15. Among them, the product magnesium oxide enters the powder heat exchange device 16 for cooling, and the sensible heat it carries is recovered by the air, and the heated air is sent to the combustion chamber 7 for combustion. The carbon dioxide gas separated by the gas-solid separation device 15 enters the magnesite preheating device 13 and the magnesite drying device 10 successively, and is used for drying and preheating the magnesite raw material. The cooled carbon dioxide gas passes through the cyclone separator 11 and the bag dust removal device 12 to reduce the particulate matter content, and the water vapor in the gas is removed by the dehydration device 17, and is recycled or recovered. The above-mentioned journey 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 split through the valve 19, one part of which enters the high-temperature heat exchange device 8 to be heated to a suitable temperature and sent back to the calcining furnace 14, and the other part is further split through the valve 20. A part of the carbon dioxide gas split through the valve 20 can be directly recovered for external sale or subsequent process production, and a part can be returned to the pyrolysis furnace 4 to participate in the reaction of biochar according to production needs.

[0075] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, but not to limit them, let alone the patent scope of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions 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 in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A polygeneration method of biomass pyrolysis coupled with magnesite calcination, characterized in that: The steps include: The biomass raw materials are fed into the biomass pyrolysis furnace, and the biomass raw materials are pyrolyzed in the biomass pyrolysis furnace to generate biomass charcoal and biomass gas; The biomass gas discharged from the biomass pyrolysis furnace is sent into the combustion chamber for combustion, and part of the combustion product is sent into the biomass pyrolysis furnace for heat supply, and the other part is sent into the heat exchanger; Dry and preheat the magnesite to above 400°C; The dried and preheated magnesite is sent to the calcining furnace, where it decomposes to produce carbon dioxide and magnesium oxide. The magnesium oxide is cooled by heat exchange and then sent to the silo to obtain magnesium oxide. The high-temperature carbon dioxide gas discharged from the calcining furnace is used to dry and preheat the magnesite. Part of the high-temperature carbon dioxide gas after cooling is recovered, part of it is sent to the biomass pyrolysis furnace to react with biochar to produce carbon monoxide and multi-porous biochar, and another part enters the heat exchanger to increase the temperature to more than 1000°C. After the temperature is increased, it is passed into the calcining furnace for calcination and smelting of magnesite.

2. The polygeneration method of biomass pyrolysis coupled with magnesite calcination as claimed in claim 1, characterized in that: Air is used to heat exchange and cool the magnesium oxide discharged from the calcining furnace, and the air heated by heat exchange is introduced into the combustion chamber to assist combustion and realize waste heat recovery and utilization.

3. The polygeneration method of biomass pyrolysis coupled with magnesite calcination as claimed 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 a drying device, and fed into the biomass pyrolysis furnace through an automatic feeding mechanism; The biomass raw material is dried using the combustion product discharged from the combustion chamber and passed through the heat exchanger.

4. A polygeneration system of biomass pyrolysis coupled with magnesite calcination, characterized in that: It includes biomass raw material feeding system, magnesite feeding system, biomass pyrolysis furnace, combustion chamber, calcining furnace, high temperature heat exchange device, powder heat exchange device; The receiving end of the biomass raw material feeding system is used to receive the biomass raw material, and the feeding end of the biomass raw material feeding system is connected to the top of the biomass pyrolysis furnace; The gas discharge end of the biomass pyrolysis furnace is connected to the interior of the combustion chamber; The smoke 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 end of the high-temperature heat exchange device; The receiving end of the magnesite feeding system is used to receive the 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 pipeline, and the magnesium oxide powder discharge pipeline is connected to a powder heat exchange device; The calcining furnace is connected to a carbon dioxide gas exhaust pipeline, which is connected to a magnesite feeding system. The carbon dioxide gas exhausted from the calcining furnace provides drying and preheating for the magnesite fed into the calcining furnace.

5. The polygeneration system of biomass pyrolysis coupled with magnesite calcination as claimed in claim 4, characterized in that: The primary outlet of the high-temperature heat exchange device is connected to the biomass raw material feeding system; the secondary inlet of the high-temperature heat exchange device is connected to the exhaust end of the magnesite feeding system, and the secondary outlet of the high-temperature heat exchange device is connected to the calcining furnace.

6. The polygeneration system of biomass pyrolysis coupled with magnesite calcination as claimed in claim 5, characterized in that: 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 end of the high-temperature heat exchange device are connected to a first multi-channel valve, and a first connecting pipe is connected between the first multi-channel valve and the second multi-channel valve; The second multi-channel valve is connected with a second connecting pipe and a carbon dioxide recovery pipe, and the second connecting pipe is connected with the inside of the biomass pyrolysis furnace.

7. The polygeneration system of biomass pyrolysis coupled with magnesite calcination as claimed in claim 6, characterized in that: 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 end of the powder heat exchange device, and the primary side outlet end of the powder heat exchange device serves as the magnesium oxide discharge end; the secondary side inlet end of the powder heat exchange device is connected to the air inlet pipe, and the secondary side outlet end of the powder heat exchange device is connected to the combustion chamber.

8. The polygeneration system of biomass pyrolysis coupled with magnesite calcination as claimed in claim 4, characterized in that: The biomass raw material feeding system includes a screening machine, a crusher, a biomass raw material drying equipment, and a smoke exhaust device; The feed end of the screening machine is used for biomass raw materials to enter, the screening discharge end of the screening machine is connected to the feed 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 discharge end of the high-temperature heat exchange device 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 smoke exhaust device.

9. The polygeneration system of biomass pyrolysis coupled with magnesite calcination as claimed in claim 7, characterized in that: The magnesite feeding system includes a magnesite drying device, a cyclone separator, a preheating device, a bag dust removal device, a dehydration device, and a first induced draft fan; The inlet end of the magnesite drying device is the magnesite feeding end, the material outlet end of the magnesite drying device is connected to the material inlet end of the cyclone separator, the material outlet end of the cyclone separator is connected to the material inlet end of the preheating device, and the material outlet end of the preheating device is connected to the inlet end of the calcining furnace; The separation end of the cyclone separator is connected to the material inlet end of the bag dust removal device, the material outlet end of the bag dust removal device is connected to the material inlet end of the preheating device, the gas discharge pipe of the gas-solid separation device is connected to the material inlet end 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 dust removal device 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.

10. The polygeneration system of biomass pyrolysis coupled with magnesite calcination as claimed in claim 6, characterized in that: It also includes a biomass gas processing 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 processing device, the discharge end of the biomass gas processing device is connected to the second induced draft fan, and the second induced draft fan is connected to the combustion chamber.

Images