Biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system and method

Abstract

The present invention discloses a biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system and method, which includes: a fluidized bed pyrolysis carbonization reactor, having an axially extending shell, a feed port provided on the shell, and a heated immersion pipe provided in the shell; a particle bed-cyclone reforming purification reactor, having a cyclone shell, a built-in particle bed and an exhaust pipe arranged in sequence from the outside to the inside, the exhaust pipe being connected to the shell through a circulation branch pipe, and the circulation branch pipe being used to return the gaseous product with a carbon dioxide concentration lower than a preset value in the exhaust pipe to the shell; a plurality of air flow holes are provided on the side wall of the built-in particle bed, and the upper end of the built-in particle bed is connected to the lower end of the shell; the upper end of the cyclone shell is connected to the upper end of the shell, and the cyclone shell is provided with a first gas inlet and a slag discharge port; a lifting pipe assembly is used to lift and transport the solid phase discharged from the particle bed-cyclone reforming purification reactor into the shell. The present invention has the advantage of high biomass particle pyrolysis carbonization conversion rate.

Description

Technical Field

[0001] The present invention relates to the field of energy and chemical technology, and in particular to a biomass fluidized bed pyrolysis and carbonization coupled carbon dioxide circulation system and method. Background Art

[0002] Due to the shortage of fossil fuels and the large amount of pollutants produced by their combustion, the development and utilization of abundant and relatively clean biomass energy has attracted attention. Biomass offers both environmental and economic advantages over fossil fuels (natural gas, coal, and oil). First, biomass provides a continuous supply of raw materials, unaffected by fluctuations in global energy prices or uncertainties in the supply of imported fuels, thus reducing dependence on fossil fuels. Second, biomass is a CO2-neutral energy source throughout its life cycle, resulting in net zero CO2 emissions.

[0003] One of the important means for the comprehensive utilization of biomass energy is pyrolysis carbonization technology. Pyrolysis carbonization is a thermochemical conversion process in which biomass is thermally decomposed in an anaerobic or anoxic environment to produce three-phase products: biochar (solid), bio-oil (liquid) and gas (biogas). In order to produce more biochar, a slower heating rate and a longer solid phase residence time are generally adopted, and pyrolysis is carried out at a lower reaction temperature. In addition to biochar products, pyrolysis carbonization also produces combustible gas, vinegar liquid and tar. The biochar produced by biomass pyrolysis can be used as an organic fertilizer, soil conditioner, fertilizer slow-release carrier, fuel, sewage purification adsorbent, metallurgical reducing agent, bio-based composite material and CO2 sequestration agent, and has high economic value and environmental benefits.

[0004] The pyrolysis carbonization of biomass is mainly an endothermic reaction. Generally, the carbonization process is divided into three stages: the first stage is the drying stage, the temperature is less than 150°C, the raw materials absorb heat in the reactor, and water evaporates and escapes; the second stage is the volatile pyrolysis stage, the reaction temperature is about 150°C ~ 300°C, which is mainly an endothermic reaction, the chemical bonds of biomass macromolecules are broken and rearranged, and organic volatiles are produced, containing water, carbon dioxide, carbon monoxide, acetic acid and other components; the third stage is the comprehensive carbonization stage, the reaction temperature is greater than 300°C, the biomass undergoes a violent pyrolysis reaction, producing more tar, vinegar liquid and combustible gases including methane, ethylene, carbon monoxide, etc., and generating solid biochar.

[0005] The calorific value and composition of the gaseous products produced during the biomass pyrolysis carbonization process depend on the type and amount of pyrolysis carbonizing agent used. Currently, the pyrolysis carbonizing agents used are mostly air, water vapor, and mixtures thereof. However, the preparation of water vapor requires a large amount of energy, so the energy consumption of the process system that replenishes a large amount of water vapor is relatively high. Using CO2 instead of water vapor or air as a pyrolysis carbonizing agent has the following advantages: first, it reduces the energy required for water vapor evaporation; second, the H2 / CO ratio in the synthesis gas is easy to adjust to meet specific industrial requirements; fourth, it is beneficial to the recycling of CO2 and the reduction of net CO2 emissions; fifth, CO2 can produce more volatiles in the activated carbon, thereby improving the pyrolysis carbonization rate.

[0006] At present, the most widely used are fixed bed (uplifting, downdraft, cross) pyrolysis carbonization reactors and fluidized bed (bubbling fluidized bed, circulating fluidized bed) pyrolysis carbonization reactors. In fixed bed pyrolysis carbonization reactors, due to the low and uneven heat and mass transfer between the biomass raw material and the pyrolysis carbonization medium, a large amount of tar and coke will be produced. On the contrary, in the fluidized bed pyrolysis carbonization reactor, there is good mixing and gas-solid contact between the biomass raw material and the pyrolysis carbonization medium, which improves the reaction rate and conversion efficiency. The efficient heat and mass transfer characteristics enable the fluidized bed to adapt to various types of biomass with different compositions and calorific values. In addition, by using bed material as a heat transfer medium and catalyst, the tar concentration in the product gas can be reduced and the product gas quality can be improved. Based on the above, fluidized beds are widely used in biomass pyrolysis carbonization processes.

[0007] Existing fluidized bed biomass pyrolysis carbonization technology suffers from high carbon dioxide and tar content in the product gas, low carbon conversion rate, and low overall energy efficiency of the pyrolysis carbonization system. This requires the addition of expensive and efficient gas purification equipment to further process the crude product gas, resulting in a complex process route and high overall production costs. Furthermore, due to the variability in size, shape, and reactivity of biomass, biomass particles are typically elongated after pulverization. Established principles applicable to spherical particles may not be directly applicable to elongated particles, which complicates the handling of such non-spherical particles in fluidized bed pyrolysis carbonization reactors.

[0008] Therefore, it is urgent to develop a new type of biomass pyrolysis carbonization coupled carbon dioxide circulation technology to solve the key technical problems such as low carbon conversion rate, high energy consumption and low flue gas carbon dioxide concentration in the biomass pyrolysis carbonization process, and achieve negative carbon emissions in the pyrolysis carbonization process. Summary of the Invention

[0009] The purpose of the present invention is to provide a biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system and method, which at least solves the problems of low carbon conversion rate and high energy consumption in existing biomass pyrolysis carbonization technology.

[0010] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0011] The present invention provides a biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system, comprising: a fluidized bed pyrolysis carbonization reactor, having an axially extending shell, the shell being provided with a feed port for biomass particles to enter, and a heating immersion pipe being provided in the shell; a particle bed-cyclone reforming purification reactor, having a cyclone shell, a built-in particle bed inserted from the upper end of the cyclone shell into the cyclone shell and extending axially, and an exhaust pipe inserted from the upper end of the built-in particle bed into the built-in particle bed and extending axially, the exhaust pipe being connected to the cyclone shell through a circulation branch pipe. The shells are connected, and the circulation branch pipe is used to return the gaseous product with a carbon dioxide concentration lower than a preset value in the smoke exhaust pipe to the shell; a plurality of air flow holes are provided on the side wall of the built-in particle bed, and the upper end of the built-in particle bed is connected to the lower end of the shell; the upper end of the cyclone outer shell is connected to the upper end of the shell, the upper end of the cyclone outer shell is provided with a first gas inlet, and the lower end of the cyclone outer shell is provided with a slag discharge port; a lifting pipe assembly is used to lift the solid phase discharged from the particle bed-cyclone reforming purification reactor and transport it to the shell.

[0012] Specifically, the lifting pipe assembly includes a pre-lifting section, a lifting section and a cyclone section connected in sequence, the lower end of the pre-lifting section is connected to the lower end of the built-in particle bed, the lower end of the cyclone section is connected to the lower end of the shell, the lower end of the pre-lifting section is provided with a second gas inlet, and the upper end of the cyclone section is provided with a dust exhaust port.

[0013] Preferably, the biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system further includes a returner, which is connected between the shell and the built-in particle bed, and a third gas inlet is provided at the lower end of the returner.

[0014] Specifically, the returner is connected to the shell through a first inclined tube, the built-in particle bed is connected to the returner through a second inclined tube, the pre-lifting section is connected to the built-in particle bed through a third inclined tube, and the cyclone section is connected to the shell through a fourth inclined tube.

[0015] Furthermore, a gas distributor is provided in the shell, and the gas distributor is located below the heating immersion tube, and the inlet of the gas distributor is connected to the circulation branch pipe.

[0016] Furthermore, the biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system further includes a cooling separator, which is connected to the free end of the exhaust pipe.

[0017] Specifically, when the carbon dioxide concentration in the gaseous product in the exhaust pipe is lower than a preset value, the circulation branch pipe is opened; when the carbon dioxide concentration in the gaseous product in the exhaust pipe is not lower than the preset value, the circulation branch pipe is cut off.

[0018] Another object of the present invention is to provide a method for coupling pyrolysis and carbonization of a biomass fluidized bed with carbon dioxide circulation, which is applicable to the biomass fluidized bed pyrolysis and carbonization coupled with carbon dioxide circulation system as described above, comprising: opening the heating immersion tube to preheat the shell, introducing biomass particles into the shell from the feed port, the biomass particles undergoing pyrolysis and carbonization reaction under the action of the heating immersion tube, and respectively transporting the gaseous phase products and solid phase products produced by the pyrolysis and carbonization reaction to the cyclone outer shell and the built-in particle bed; introducing high-temperature oxygen-rich gas into the first gas inlet, causing the gaseous phase products transported to the cyclone outer shell and the solid phase products transported to the built-in particle bed to undergo reforming and purification reactions, and transporting the gaseous phase products and solid phase products produced by the reforming and purification reactions to the exhaust pipe and the lifting pipe assembly respectively; introducing fluidizing gas into the lifting pipe assembly to lift the solid phase products transported to the lifting pipe assembly and transport them into the shell.

[0019] Preferably, when the carbon dioxide concentration in the gaseous product in the exhaust pipe is lower than a preset value, the gaseous product enters the shell through the circulation branch pipe, and the carbon dioxide in the gaseous product acts as a pyrolysis carbonization agent to participate in the pyrolysis carbonization reaction of the biomass particles.

[0020] Specifically, the reaction temperature of the fluidized bed pyrolysis carbonization reactor is 600°C to 800°C, and the reaction temperature of the particle bed-cyclone reforming purification reactor is 1200°C to 1400°C.

[0021] The characteristics and advantages of the present invention are: the biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system provided by the present invention sets a heating immersion tube in the shell of the fluidized bed pyrolysis carbonization reactor to weaken the influence of the material shape of the biomass, strengthen the particle mixing, adjust the bed temperature, and thus improve the biomass pyrolysis carbonization conversion rate; by setting up a particle bed-cyclone reforming purification reactor, the coke produced by the biomass pyrolysis carbonization is used as the built-in particle bed bed material of the particle bed-cyclone reforming purification reactor, the catalytic cracking of tar in the gas production is strengthened, the tar concentration can be further reduced, and at the same time, the problems of short contact time between tar and coke and poor catalytic effect in the fluidized bed pyrolysis carbonization reactor are solved, and the gas-producing particle bed is finely purified. , realizing the coupling of tar reforming, coke pyrolysis carbonization and gas purification process, improving the cleanliness and calorific value of gas production, realizing negative carbon emissions in the pyrolysis carbonization process, and reducing the use of fossil fuels and lowering operating costs compared with the multi-stage process flow; and by setting a circulation branch pipe, the gas phase product with substandard carbon dioxide concentration in the exhaust pipe is returned to the shell as a pyrolysis carbonization agent, realizing the recycling of heat carried by the gas phase, improving the CO / H2 ratio in the gas production, reducing the energy consumption of the system, and improving the utilization rate of carbon in the biomass; and by setting a lifting pipe assembly, the solid phase output from the granular bed-cyclone reforming purification reactor is returned to the shell of the fluidized bed pyrolysis carbonization reactor, realizing the recycling of heat carried by the solid phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a schematic structural diagram of a biomass fluidized bed pyrolysis and carbonization coupled with a carbon dioxide circulation system provided in an embodiment of the present invention.

[0024] Description of Figure Numbers:

[0025] 100. Fluidized bed pyrolysis carbonization reactor; 110. Shell; 111. Feed inlet; 112. Ash discharge port; 120. Heating immersion tube; 130. Gas distributor;

[0026] 200, particle bed-cyclone reforming purification reactor; 210, cyclone housing; 211, first gas inlet; 212, slag discharge port; 220, built-in particle bed; 230, smoke exhaust pipe;

[0027] 300, riser assembly; 310, pre-lift section; 311, second gas inlet; 320, lift section; 330, cyclone section; 331, dust outlet;

[0028] 400, screw feeder;

[0029] 500, material return device; 501, third gas inlet;

[0030] 600, cooling separator;

[0031] 10. Circulation branch pipe;

[0032] 20. First inclined tube;

[0033] 30. Second inclined tube;

[0034] 40. The third inclined tube;

[0035] 50. The fourth oblique tube. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, the present invention provides a biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system, comprising: a fluidized bed pyrolysis carbonization reactor 100, having an axially extending shell 110, the shell 110 is provided with a feed inlet 111 for biomass particles to enter, and the shell 110 is provided with a heating immersion pipe 120; a particle bed-cyclone reforming purification reactor 200, having a cyclone shell 210, a built-in particle bed 220 inserted from the upper end of the cyclone shell 210 into the cyclone shell 210 and extending axially, and an exhaust pipe 230 inserted from the upper end of the built-in particle bed 220 into the built-in particle bed 220 and extending axially, the exhaust pipe 230 is passed through The circulation branch pipe 10 is connected to the shell 110, and the circulation branch pipe 10 is used to return the gaseous product with a carbon dioxide concentration lower than a preset value in the smoke exhaust pipe 230 to the shell 110; a plurality of air flow holes are provided on the side wall of the built-in particle bed 220, and the upper end of the built-in particle bed 220 is connected to the lower end of the shell 110; the upper end of the cyclone outer shell 210 is connected to the upper end of the shell 110, and the upper end of the cyclone outer shell 210 is provided with a first gas inlet 211, and the lower end of the cyclone outer shell 210 is provided with a slag discharge port 212; the lifting pipe assembly 300 is used to lift the solid phase discharged from the particle bed-cyclone reforming purification reactor 200 and transport it to the shell 110.

[0038] Specifically, such as Figure 1As shown, the biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system includes a fluidized bed pyrolysis carbonization reactor 100, a particle bed-cyclone reforming purification reactor 200, and a riser assembly 300, which are sequentially connected to form a closed loop. The fluidized bed pyrolysis carbonization reactor 100 includes a shell 110, which is provided with a feed inlet 111 and an ash discharge port 112. A heating immersion pipe 120 is provided in the shell 110 for heating the biomass particles entering from the feed inlet 111. The particle bed-cyclone reforming purification reactor 200 includes a cyclone housing 110, an internal particle bed 220 inserted within the cyclone housing 110, and a smoke exhaust pipe 230 inserted within the internal particle bed 220. The smoke exhaust pipe 230 and the internal particle bed 220 are arranged coaxially and parallel to the cyclone housing 110. The internal particle bed 220 has a sleeve-type sandwich structure, including inner and outer walls with multiple airflow holes. The inner and outer walls form a flow channel for the solid phase produced by the pyrolysis and carbonization reaction of the biomass particles. Preferably, the inner and outer walls are made of Johnson mesh, and the material can be selected from carbon steel or stainless steel, etc., depending on the characteristics of the biomass particles and their products. The riser assembly 300 is connected between the particle bed-cyclone reforming purification reactor 200 and the fluidized bed pyrolysis and carbonization reactor 100. The lower end of the riser assembly 300 is provided with a second gas inlet 311 for introducing fluidizing gas.

[0039] Specifically, the biomass particles entering the shell 110 from the feed port 111 are pyrolyzed at the pyrolysis reaction temperature provided by the heated immersion tube 120 to generate tar (gaseous), coke, ash and coarse product gas containing methane, ethylene, carbon monoxide, etc., and then the tar and coarse product gas flow out from the upper end of the shell 110 and enter the cyclone shell 210 of the particle bed-cyclone reforming purification reactor 200, and the coke enters the built-in particle bed 220 of the particle bed-cyclone reforming purification reactor 200 from the lower end of the shell 110, and forms a coke bed layer in the built-in particle bed 220, and the ash is discharged from the ash discharge port 112 set at the lower end of the shell 110. After high-temperature, oxygen-rich gas is introduced into the first gas inlet 211 of the cyclone housing 210, the coarse product gas is first removed from the cyclone housing 210 to remove tar, moisture, and coarse biochar it carries. Simultaneously, carbon monoxide is burned to produce carbon dioxide, and tar is further cracked and removed under the catalytic action of the coke's pyrolysis. The high-temperature product gas then cross-flows through the meshed sidewalls of the internal particle bed 220, where the fine biochar it carries is further adsorbed and purified by the coke layer within the internal particle bed 220. After catalytic reduction, the high-temperature product gas containing carbon dioxide is obtained and discharged from the particle bed-cyclone reforming purification reactor 200 through the exhaust pipe 230 located within the internal particle bed 220. When the carbon dioxide concentration in the high-temperature product gas is below a preset value, the high-temperature product gas enters the circulation branch pipe 10 from the exhaust pipe 230 and is transported back to the housing 110 via the circulation branch pipe 10 to serve as a pyrolysis carbonization agent for the pyrolysis and carbonization reaction of the biomass particles. When the carbon dioxide concentration in the high-temperature product gas is not below the preset value, the high-temperature product gas is discharged from the exhaust pipe 230 for processing and collection. After pyrolysis, the coke particles carrying fine biochar enter the riser assembly 300 from the lower end of the particle bed-cyclone reforming purification reactor 200, and the bottom slag carrying coarse biochar after the reaction is discharged from the slag discharge port 212 provided at the lower end of the cyclone shell 210. After the fluidizing gas is introduced into the second gas inlet 311 of the riser assembly 300, the coke particles in the riser assembly 300 are lifted and transported back to the shell 110 to realize the recycling of heat carried by the solid phase. It should be noted that fine biochar and coarse biochar are also important products of biomass particle pyrolysis carbonization. By classifying and collecting them according to particle size, the economic benefits of biomass particle pyrolysis carbonization can be further improved.

[0040] The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system provided by the present invention sets a heating immersion tube 120 in the shell 110 of the fluidized bed pyrolysis carbonization reactor 100 to weaken the influence of the material shape of the biomass, strengthen the particle mixing, adjust the bed temperature, and thus improve the biomass pyrolysis carbonization conversion rate; by setting a particle bed-cyclone reforming purification reactor 200, the coke produced by the biomass pyrolysis carbonization is used as the bed material of the built-in particle bed 220 of the particle bed-cyclone reforming purification reactor 200, the catalytic cracking of tar in the gas production is strengthened, the tar concentration can be further reduced, and at the same time, the problems of short contact time between tar and coke and poor catalytic effect in the fluidized bed pyrolysis carbonization reactor 100 are solved, and the gas-producing particle bed is finely purified to achieve tar. The coupling of reforming, coke pyrolysis carbonization and gas purification processes improves the cleanliness and calorific value of the produced gas, achieves negative carbon emissions in the pyrolysis carbonization process, reduces the use of fossil fuels and reduces operating costs compared to multi-stage process flows; and by setting a circulation branch pipe 10, the gas phase product with substandard carbon dioxide concentration in the exhaust pipe 230 is returned to the shell 110 as a pyrolysis carbonization agent, thereby achieving the recycling of heat carried by the gas phase, improving the CO / H2 ratio in the produced gas, reducing the energy consumption of the system, and improving the utilization rate of carbon in the biomass; and by setting a lifting pipe assembly 300, the solid phase output from the granular bed-cyclone reforming purification reactor 200 is returned to the shell 110 of the fluidized bed pyrolysis carbonization reactor 100, thereby achieving the recycling of heat carried by the solid phase.

[0041] According to one embodiment of the present invention, when the carbon dioxide concentration in the gaseous product in the exhaust pipe 230 is lower than a preset value, the circulation branch pipe 10 is opened; when the carbon dioxide concentration in the gaseous product in the exhaust pipe 230 is not lower than the preset value, the circulation branch pipe 10 is cut off. Specifically, a sensor for detecting the carbon dioxide concentration in the gaseous product is provided on the exhaust pipe 230, and a three-way control valve is provided at the connection between the exhaust pipe 230 and the circulation branch pipe 10. When the sensor detects that the carbon dioxide concentration in the gaseous product is lower than a preset value, the three-way control valve cuts off the exhaust pipe 230 and connects the circulation branch pipe 10 and the exhaust pipe 230. The gas enters the circulation branch pipe 10 from the exhaust pipe 230 and is transported back to the shell 110 through the circulation branch pipe 10 to serve as a pyrolysis carbonization agent for the pyrolysis and carbonization reaction of biomass particles. When the sensor detects that the carbon dioxide concentration in the gaseous product is not lower than a preset value, the three-way control valve cuts off the circulation branch pipe 10 and connects the exhaust pipe 230. The gas is discharged from the exhaust pipe 230 for processing and collection. The preset value of the carbon dioxide concentration is set according to the final application requirements of the collected carbon dioxide, that is, the preset value of the carbon dioxide concentration is set according to the target purity requirements of the final use conditions of the collected carbon dioxide. For example, if a certain downhole oil recovery technology requires the use of carbon dioxide with a purity of 96%, the preset value of the carbon dioxide concentration can be set to 96%. When the detection sensor detects that the carbon dioxide concentration in the gas phase product in the exhaust pipe 230 is lower than 96%, the gas phase product returns to the shell 110 through the circulation branch pipe 10 to participate in the reaction and circulate until the carbon dioxide in the gas phase product in the exhaust pipe 230 accumulates through circulation and reaches a concentration of 96%, and is then discharged and collected from the exhaust pipe 230.

[0042] In this embodiment, the selective connection between the circulation branch pipe 10 and the smoke exhaust pipe 230 can also be achieved by respectively providing a first control valve and a second control valve on the smoke exhaust pipe 230 and the circulation branch pipe 10 , and the present invention does not impose any limitation on this.

[0043] According to one embodiment of the present invention, Figure 1 As shown, in order to realize the continuous automatic feeding of biomass particles in the fluidized bed pyrolysis carbonization reactor 100 , the feed port 111 is connected to the biomass particle silo through a screw feeder 400 .

[0044] According to a preferred embodiment of the present invention, Figure 1 As shown, a gas distributor 130 is further provided in the housing 110. The gas distributor 130 is located below the heated immersion tube 120, and the inlet of the gas distributor 130 is connected to the circulation branch pipe 10. By providing the gas distributor 130, the gas phase entering the fluidized bed pyrolysis carbonization reactor 100 through the circulation branch pipe 10 is evenly dispersed into the biomass particles, achieving sufficient fluidization of the biomass particles in the housing 110, thereby improving the reaction efficiency of the pyrolysis carbonization of the biomass particles.

[0045] According to one embodiment of the present invention, Figure 1 As shown, the lifting tube assembly 300 includes a pre-lifting section 310, a lifting section 320 and a cyclone section 330 connected in sequence, the lower end of the pre-lifting section 310 is connected to the lower end of the built-in particle bed 220, the lower end of the cyclone section 330 is connected to the lower end of the shell 110, the lower end of the pre-lifting section 310 is provided with a second gas inlet 311, and the upper end of the cyclone section 330 is provided with a dust exhaust port 331. Specifically, after fluidizing gas is introduced into the second gas inlet 311, the coke particles entering the pre-elevation section 310 from the lower end of the particle bed-cyclone reforming purification reactor 200 are pneumatically conveyed by the fluidizing gas and lifted into the elevation section 320. Under the continued pneumatic conveying of the fluidizing gas, the coke particles enter the cyclone section 330 from the upper end of the elevation section 320. Fine biochar entrained in the coke particles is discharged through the dust outlet 331 provided at the upper end of the cyclone section 330. The purified coke particles are discharged from the lower end of the cyclone section 330 and returned to the fluidized bed pyrolysis and carbonization reactor 100, thereby recycling the heat carried by the solid phase. Preferably, to further improve the reaction efficiency of the pyrolysis and carbonization of biomass particles, the fluidizing gas introduced into the second gas inlet 311 is oxygen-enriched gas.

[0046] According to a preferred embodiment of the present invention, Figure 1 As shown, the biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system further includes a returner 500, which is connected between the shell 110 and the built-in particle bed 220, and a third gas inlet 501 is provided at the lower end of the returner 500. Specifically, the returner 500 has an axially extending shell, and a partition is provided inside the shell, one end of the partition is connected to the inner top wall of the shell 110, and the other end of the partition is suspended, that is, the partition divides the interior of the shell 110 into two chambers connected at the lower end. By introducing high-temperature oxygen-rich gas into the third gas inlet 501, the coke particles produced by the pyrolysis and carbonization reaction of the biomass particles in the fluidized bed pyrolysis and carbonization reactor 100 are continuously transported to the built-in particle bed 220 of the particle bed-cyclone reforming purification reactor 200, so as to effectively avoid gas backflow. At the same time, the introduced high-temperature oxygen-rich gas also has the effects of supplementing heat, removing coke and removing acid for the coke.

[0047] According to one embodiment of the present invention, Figure 1As shown, the returner 500 is connected to the housing 110 via the first inclined tube 20, the built-in particle bed 220 is connected to the returner 500 via the second inclined tube 30, the pre-lift section 310 is connected to the built-in particle bed 220 via the third inclined tube 40, and the cyclone section 330 is connected to the housing 110 via the fourth inclined tube 50. Specifically, the sequentially connected fluidized bed pyrolysis and carbonization reactor 100, the first inclined tube 20, the returner 500, the second inclined tube 30, the built-in particle bed 220, the third inclined tube 40, the riser assembly 300, and the fourth inclined tube 50 form a solid-phase circulation path, through which the coke produced by the pyrolysis and carbonization reaction of the biomass particles is recycled, carrying heat in the solid phase.

[0048] According to a preferred embodiment of the present invention, Figure 1 As shown, the biomass fluidized bed pyrolysis carbonization coupled with carbon dioxide circulation system also includes a cooling separator 600, which is connected to the free end of the exhaust pipe 230. Thus, the gas phase produced by the granular bed-cyclone reforming purification reactor 200, whose carbon dioxide concentration meets the preset requirements, is processed by the cooling separator 600 to obtain aqueous vinegar liquid and high-concentration carbon dioxide as pyrolysis products, which are then classified and collected. The carbon dioxide can be used in downhole high-efficiency oil recovery processes to achieve carbon dioxide sequestration. It can also be used in traditional fields such as metallurgical welding, chemical machinery, and medical treatment, as well as in high-tech fields such as bioengineering, microelectronic laser technology, biodegradable plastic production, and supercritical pharmaceuticals.

[0049] Another object of the present invention is to provide a method for coupling pyrolysis and carbonization of a biomass fluidized bed with carbon dioxide circulation, which is applicable to the above-mentioned biomass fluidized bed pyrolysis and carbonization coupled with carbon dioxide circulation system, comprising: opening the heating immersion tube 120 to preheat the shell 110, introducing biomass particles into the shell 110 from the feed port 111, the biomass particles undergoing pyrolysis and carbonization reaction under the action of the heating immersion tube 120, and respectively delivering the gaseous phase product and solid phase product produced by the pyrolysis and carbonization reaction to the cyclone outer shell 210 and the built-in particle bed 220; introducing high-temperature oxygen-rich gas into the first gas inlet 211, causing the gaseous phase product transported to the cyclone outer shell 210 and the solid phase product transported to the built-in particle bed 220 to undergo a reforming and purification reaction, and respectively delivering the gaseous phase product and solid phase product produced by the reforming and purification reaction to the exhaust pipe 230 and the riser assembly 300; introducing fluidizing gas into the riser assembly 300 to lift the solid phase product transported to the riser assembly 300 and transport it into the shell 110.

[0050] Specifically, the heating immersion pipe 120 is first turned on to preheat the shell 110, and then the screw feeder 400 is turned on to transport the biomass particles in the silo to the fluidized bed pyrolysis carbonization reactor 100. Under the action of the heating immersion pipe 120, the internal temperature of the shell 110 is rapidly raised to the pyrolysis carbonization reaction temperature of the biomass particles. The cellulose in the biomass particles is thermally decomposed to produce volatile substances (coarse gas production) and tar, and the lignin in the biomass particles is decomposed to produce coke particles, which carry a large amount of coarse tar and ash. The produced gas is fed from the upper end of the fluidized bed pyrolysis carbonization reactor 100 into the inlet of the cyclone housing 210 of the particle bed-cyclone reforming purification reactor 200. The remaining condensate is separated into an aqueous vinegar phase and an oily tar phase as pyrolysis byproducts. The coke particles enter the return feeder 500 through the first inclined pipe 20. After passing through the return feeder 500, they are transported by the second inclined pipe 30 to the internal particle bed 220 of the particle bed-cyclone reforming purification reactor 200, forming the bed layer of the internal particle bed 220 and providing catalytic and purification functions. During the coke particle transportation process, high-temperature oxygen-rich gas is introduced into the third gas inlet 501 of the return feeder 500. The delivery rate of the high-temperature oxygen-rich gas is adjusted to ensure continuous transportation of the coke particles and prevent gas backflow. At the same time, the high-temperature oxygen-rich gas is used to supplement the reforming heat. After the reaction products of the pyrolysis and carbonization of the biomass particles in the fluidized bed pyrolysis and carbonization reactor 100 enter the particle bed-cyclone reforming purification reactor 200, high-temperature oxygen-rich gas is introduced into the first gas inlet 211 of the particle bed-cyclone reforming purification reactor 200. A portion of the coarse product gas in the cyclone housing 210 undergoes a combustion reaction with the high-temperature oxygen-rich gas to maintain a high-temperature reforming environment, while generating a large amount of carbon dioxide gas. A portion of the tar in the cyclone housing 210 is completely removed through high-temperature cracking and steam reforming reactions, and large-particle ash (coarse biochar with a particle size greater than 10 μm) is discharged from the slag discharge port 212. After reforming, the high-temperature product gas containing a large amount of carbon dioxide gas enters the built-in particle bed 220 with the vortex of the cyclone housing 210. The tar carried in the high-temperature product gas fully contacts the coke particles and is catalytically cracked into small molecular gases. The fine ash is further filtered, improving the cleanliness and calorific value of the product gas, and also increasing the carbon dioxide concentration. The coke particles in the built-in particle bed 220 move downward under the action of gravity and are transported by the third inclined pipe 40 to the pre-lifting section 310 of the lifting pipe assembly 300. After the fluidizing gas is introduced into the second gas inlet 311 of the lifting pipe assembly 300, the coke particles are lifted by the fluidizing gas and transported to the cyclone section 330 through the lifting section 320. The fine biochar entrained in the coke particles is discharged from the dust outlet 331 at the top of the cyclone section 330, and the coke particles are returned to the fluidized bed pyrolysis carbonization reactor 100 from the bottom of the cyclone section 330 through the fourth inclined pipe 50, thereby realizing the recycling of heat carried by the solid phase.

[0051] According to one embodiment of the present invention, when the carbon dioxide concentration in the gaseous product in the exhaust pipe 230 is lower than a preset value, the gaseous product enters the shell 110 through the circulation branch pipe 10, and the carbon dioxide in the gaseous product participates in the pyrolysis carbonization reaction of the biomass particles as a pyrolysis carbonization agent. Specifically, when the carbon dioxide concentration of the high-temperature product gas produced by the particle bed-cyclone reforming purification reactor 200 does not reach the preset value, it is reintroduced into the fluidized bed pyrolysis carbonization reactor 100 through the circulation branch pipe 10 as a pyrolysis carbonization agent for the pyrolysis carbonization reaction of the biomass particles. The biomass particles and carbon dioxide added to the fluidized bed pyrolysis carbonization reactor 100 by the screw feeder 400 are vigorously mixed. Under the action of the heated immersion rod, strong heat and mass exchange occurs, causing the internal temperature of the shell 110 to quickly rise to the pyrolysis carbonization reaction temperature of the biomass particles. When the carbon dioxide concentration of the high-temperature gas produced by the granular bed-cyclone reforming purification reactor 200 reaches a preset value, it directly enters the cooling separator 600 through the exhaust pipe 230 to obtain aqueous vinegar liquid and high-concentration carbon dioxide. The vinegar liquid and carbon dioxide are discharged from the liquid discharge port and exhaust port of the cooling separator 600 respectively, realizing the classified collection of pyrolysis products.

[0052] The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation method provided in the embodiment of the present invention uses high-temperature carbon dioxide whose concentration does not reach a preset value as a pyrolysis carbonization agent to improve the pyrolysis carbonization efficiency of biomass particles while realizing the recycling of heat in the gas phase. The char produced by the pyrolysis carbonization of biomass particles is purified and recovered into the fluidized bed pyrolysis carbonization reactor 100 to realize the recycling of heat in the solid phase. This is an important way to further improve resource utilization efficiency, promote green industrial upgrading and transformation, and build a green circular economy. It is of great significance to offset the difficult-to-reduce carbon dioxide and non-carbon dioxide greenhouse gas emissions.

[0053] According to one embodiment of the present invention, the reaction temperature of the fluidized bed pyrolysis carbonization reactor 100 is 600°C to 800°C, and the reaction temperature of the particle bed-cyclone reforming purification reactor 200 is 1200°C to 1400°C. Specifically, the reaction temperature for the pyrolysis carbonization of biomass particles in the fluidized bed pyrolysis carbonization reactor 100 is provided by the heated immersion tube 120, and the temperature range is 600°C to 800°C; the reaction temperature for the tar reforming, coke pyrolysis carbonization, and gas purification in the particle bed-cyclone reforming purification reactor 200 is provided by the heat carried by the solid particles and the high-temperature oxygen-rich gas, and the temperature range is 1200°C to 1400°C.

[0054] The above descriptions are only several embodiments of the present invention. Those skilled in the art may make various changes or modifications to the embodiments of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A biomass fluidized bed pyrolysis carbonization coupled with carbon dioxide circulation system, characterized in that: include: A fluidized bed pyrolysis carbonization reactor comprises an axially extending shell, the shell being provided with a feed port for biomass particles to enter, and a heating immersion pipe being provided in the shell; A particle bed-cyclone reforming purification reactor comprises a cyclone shell, a built-in particle bed inserted from the upper end of the cyclone shell into the cyclone shell and extending axially, and an exhaust pipe inserted from the upper end of the built-in particle bed into the built-in particle bed and extending axially. The exhaust pipe is connected to the shell through a circulation branch pipe, and the circulation branch pipe is used to return the gas phase product with a carbon dioxide concentration lower than a preset value in the exhaust pipe to the shell; the upper end of the built-in particle bed is connected to the lower end of the shell, and the built-in particle bed is a sleeve. The cyclone shell has a sandwich structure, comprising an inner wall and an outer wall with a plurality of air flow holes, wherein a flow channel for producing coke particles by the pyrolysis and carbonization reaction of biomass particles is formed between the inner wall and the outer wall; the upper end of the cyclone shell is connected to the upper end of the shell, and the upper end of the cyclone shell is provided with a first gas inlet for introducing high-temperature oxygen-rich gas, and the high-temperature produced gas enters the built-in particle bed along with the vortex of the cyclone shell, and the tar carried in the high-temperature produced gas fully contacts with the coke particles and is catalytically cracked into small molecular gas, and the lower end of the cyclone shell is provided with a slag discharge port; The lifting pipe assembly is used to lift the coke particles discharged from the particle bed-cyclone reforming purification reactor and transport them into the shell.

2. The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system according to claim 1 is characterized in that: The lifting pipe assembly includes a pre-lifting section, a lifting section and a cyclone section connected in sequence, the lower end of the pre-lifting section is connected to the lower end of the built-in particle bed, the lower end of the cyclone section is connected to the lower end of the shell, the lower end of the pre-lifting section is provided with a second gas inlet, and the upper end of the cyclone section is provided with a dust exhaust port.

3. The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system according to claim 2, characterized in that: The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system further includes a returner connected between the shell and the built-in particle bed, and a third gas inlet is provided at the lower end of the returner.

4. The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system according to claim 3, characterized in that: The returner is connected to the shell through a first inclined tube, the built-in particle bed is connected to the returner through a second inclined tube, the pre-lifting section is connected to the built-in particle bed through a third inclined tube, and the cyclone section is connected to the shell through a fourth inclined tube.

5. The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system according to claim 4, characterized in that: A gas distributor is further provided in the shell. The gas distributor is located below the heating immersion tube. The inlet of the gas distributor is connected to the circulation branch pipe.

6. The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system according to claim 5, characterized in that: The biomass fluidized bed pyrolysis and carbonization coupled carbon dioxide circulation system further includes a cooling separator, which is connected to the free end of the smoke exhaust pipe.

7. The biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system according to claim 1, characterized in that: When the carbon dioxide concentration in the gaseous product in the exhaust pipe is lower than a preset value, the circulation branch pipe is opened; when the carbon dioxide concentration in the gaseous product in the exhaust pipe is not lower than the preset value, the circulation branch pipe is cut off.

8. A biomass fluidized bed pyrolysis carbonization coupled with carbon dioxide circulation method, characterized in that: The method is applicable to the biomass fluidized bed pyrolysis carbonization coupled carbon dioxide circulation system according to any one of claims 1 to 7, comprising: The heating immersion tube is opened to preheat the shell, and biomass particles are introduced into the shell from the feed port. The biomass particles undergo a pyrolysis and carbonization reaction under the action of the heating immersion tube, and the gaseous and solid products produced by the pyrolysis and carbonization reaction are respectively transported to the cyclone shell and the built-in particle bed; Introducing high-temperature oxygen-rich gas into the first gas inlet to cause the gaseous product delivered to the cyclone casing and the solid product delivered to the built-in particle bed to undergo a reforming and purification reaction, and delivering the gaseous product and solid product produced by the reforming and purification reaction to the exhaust pipe and the riser assembly, respectively; Fluidizing gas is introduced into the riser assembly to lift the solid phase product conveyed to the riser assembly and convey it into the shell.

9. The biomass fluidized bed pyrolysis carbonization coupled with carbon dioxide circulation method according to claim 8, characterized in that: When the carbon dioxide concentration in the gaseous product in the exhaust pipe is lower than a preset value, the gaseous product enters the shell through the circulation branch pipe, and the carbon dioxide in the gaseous product acts as a pyrolysis carbonization agent to participate in the pyrolysis carbonization reaction of the biomass particles.

10. The biomass fluidized bed pyrolysis carbonization coupled with carbon dioxide circulation method according to claim 9, characterized in that: The reaction temperature of the fluidized bed pyrolysis carbonization reactor is 600°C to 800°C, and the reaction temperature of the particle bed-cyclone reforming purification reactor is 1200°C to 1400°C.

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