Bamboo waste staged combustion carbon-heat-electricity-carbon co-production system and method

Abstract

The invention discloses a bamboo waste staged combustion carbon-heat-electricity-carbon co-production system and method, and belongs to the field of biomass deep processing. The system comprises a gasification combustion unit, a gas-solid separation unit, a combustion heat exchange unit, a cooling compression unit, a dealkylation desulfurization unit, a dehydration drying unit and a liquefaction purification unit. The bamboo waste is gasified and combusted in the fluidized bed gasifier and then enters a gas-solid separation unit, and hot fuel gas and biomass charcoal powder are obtained; the hot fuel gas is subjected to secondary combustion and heat exchange in the combustion heat exchange unit to obtain medium-temperature medium-pressure steam and carbon dioxide-rich flue gas for heat supply and power generation; most of waste water in the carbon dioxide-rich flue gas is removed through a cooling compression unit; and further removing impurities such as hydrocarbon, sulfur, water, nitrogen, oxygen and the like in the cooled carbon dioxide-rich flue gas through a dealkylation and desulfurization unit, a dehydration and drying unit and a liquefaction and purification unit to obtain a food-grade carbon dioxide liquid product.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep processing of biomass, and particularly relates to a bamboo waste staged combustion carbon-thermal-electricity-carbon co-production system and method. Background Art

[0002] China has the richest bamboo resources in the world, and the consumption of raw bamboo is huge. However, in the processing and utilization of bamboo resources, except for the bamboo poles, the bamboo joints, bamboo branches, bamboo greens and bamboo yellows as bamboo wastes are often only buried and burned or simply roughly processed into bamboo boards and bamboo charcoal. Such a treatment method not only wastes the energy in bamboo resources in vain, but also causes certain pollution to the atmosphere. If the wasted resources can be deeply processed by scientific and technological means, considerable economic benefits will be generated.

[0003] As an important method for utilizing biomass energy, biomass pyrolysis technology has been widely applied at home and abroad. With the continuous development of technology, the focus has gradually shifted from paying attention to efficient reactors and process parameters to the overall consideration of biomass resource process systems and the improvement of product quality. Therefore, it is of great practical significance to develop a process system and method for pyrolyzing bamboo waste to co-produce high-quality products. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies in the prior art and provide a bamboo waste staged combustion carbon-thermal-electricity-carbon co-production system and method

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] In the first aspect, the present invention provides a bamboo waste staged combustion carbon-thermal-electricity-carbon co-production system, including a gasification combustion unit, a gas-solid separation unit, a combustion heat exchange unit, a cooling compression unit, a dehydrocarbonization and desulfurization unit, a dehydration and drying unit, and a liquefaction and purification unit;

[0007] The material inlet of the gasification combustion unit receives bamboo waste from the feeding system, and the gas inlet of the gasification combustion unit receives oxygen-rich gas from the air chamber; the upper outlet of the gasification combustion unit is connected to the inlet of the gas-solid separation unit through a pipeline;

[0008] The hot gas outlet of the gas-solid separation unit is connected to the hot gas inlet of the combustion heat exchange unit through a pipeline; the gas inlet of the combustion heat exchange unit receives oxygen-rich gas from the air chamber; the oxygen-rich carbon dioxide flue gas outlet of the combustion heat exchange unit is divided into three branches after passing through a pipeline provided with a dust collector, the first branch enters the cooling compression unit through a pipeline, and the second branch and the third branch return to the combustion heat exchange unit and the gasification combustion unit respectively through pipelines;

[0009] The compressed rich carbon dioxide flue gas outlet of the cooling and compression unit is connected to the hydrocarbon and sulfur removal unit through a pipeline; the purified rich carbon dioxide flue gas outlet of the hydrocarbon and sulfur removal unit is compressed again by a secondary compressor and then connected to the dehydration and drying unit; the dried rich carbon dioxide flue gas outlet of the dehydration and drying unit is connected to the liquefaction and purification unit through a pipeline; the regenerated gas outlet of the liquefaction and purification unit is returned to the dehydration and drying unit through a pipeline for recycling; the carbon dioxide liquid outlet of the liquefaction and purification unit is connected to an external carbon dioxide liquid storage tank through a pipeline to recover food-grade carbon dioxide liquid products.

[0010] Preferably, a biomass carbon powder outlet is further provided on the gas-solid separation unit, and the biomass carbon powder outlet of the gas-solid separation unit is connected to an external transition carbon bin through a pipeline; a steam outlet is further provided on the combustion and heat exchange unit, and the steam outlet of the combustion and heat exchange unit is connected to external equipment through a pipeline for heat supply or power generation; a wastewater outlet is further provided on the cooling and compression unit, and the wastewater outlet of the cooling and compression unit is connected to an external wastewater treatment system through a pipeline; a wastewater outlet is further provided on the hydrocarbon and sulfur removal unit, and the wastewater outlet of the hydrocarbon and sulfur removal unit is connected to an external wastewater treatment system through a pipeline.

[0011] Preferably, a fluidized bed gasifier is used in the gasification and combustion unit, the reaction temperature is controlled at 590 - 610 °C, and the particle size of the bamboo waste particles received is 1 - 20 mm; the purity of the rich oxygen provided by the air chamber is 90 - 95 vol%.

[0012] Preferably, the gas-solid separation unit includes a primary cyclone dust collector and a secondary cyclone separator.

[0013] Preferably, the combustion and heat exchange unit includes a combustion chamber, a water-cooled wall, an evaporative heating surface, a economizer, an air preheater, and a steam drum; after the hot gas from the gas-solid separation unit and the rich oxygen burn and release heat in the combustion chamber, they are then heat-exchanged through the water-cooled wall, the evaporative heating surface, the economizer, and the air preheater to obtain steam products and rich carbon dioxide flue gas; the temperature of the steam products is 420 - 480 °C, and the pressure is 3.6 - 4.0 MPaG; the temperature of the rich carbon dioxide flue gas is 130 °C.

[0014] Preferably, the pressure of the compressed rich carbon dioxide flue gas obtained after passing through the cooling and compression unit is in the range of 0.8 - 0.9 MPaG, and the temperature is between 32 - 40 °C.

[0015] Preferably, the hydrocarbon and sulfur removal unit includes a heat exchanger, an electric heater, a hydrocarbon removal reactor, a scrubbing tower, and a sulfur dioxide adsorption tower; a sulfur hydrocarbon conversion catalyst is filled in the hydrocarbon removal reactor; a dehydration adsorbent and a purification adsorbent are filled in the scrubbing tower; a sulfur dioxide adsorbent is installed in the sulfur dioxide adsorption tower.

[0016] Preferably, the dehydration and drying unit adopts a three-tower adsorption process. During normal operation, one drying tower adsorbs moisture, one drying tower is in the drying stage, and the other drying tower is in the cooling stage. The three drying towers switch work periodically to achieve continuous drying of the purified carbon dioxide-rich flue gas. The water content of the dried carbon dioxide-rich flue gas obtained through the dehydration and drying unit is less than 20 ppm.

[0017] Preferably, the liquefaction and purification unit includes a purification tower, a throttle valve, a refrigeration ice machine, a reboiler, and a condenser. The refrigeration ice machine is a closed refrigeration cycle system. The purity of the carbon dioxide liquid obtained through the liquefaction and purification unit is not less than 99.9 vol%.

[0018] In the second aspect, the present invention provides a method for co-producing bamboo waste hierarchical combustion carbon, heat, and electricity using the system described in the first aspect, specifically as follows:

[0019] S1: After the bamboo waste from the feeding system enters the gasification combustion unit, it is mixed and heated with the oxygen-rich gas from the air chamber, and pyrolysis gasification and combustion reactions occur to obtain a high-temperature gas containing biomass carbon powder.

[0020] S2: The high-temperature gas containing biomass carbon powder obtained in step S1 enters the gas-solid separation unit through a pipeline. After passing through the primary separation process and the secondary separation process in the gas-solid separation unit, hot gas and biomass carbon powder are obtained. Among them, the biomass carbon powder enters the transition carbon bin as a product through a pipeline.

[0021] S3: The hot gas obtained in step S2 enters the combustion heat exchange unit through a pipeline to further burn and release heat, obtaining high-temperature steam and high-temperature carbon dioxide-rich flue gas, and exchanging heat with the water-cooled wall, evaporation heating surface, economizer, and air preheater in the combustion heat exchange unit to obtain medium-temperature and medium-pressure steam and cooled carbon dioxide-rich flue gas. Among them, the medium-temperature and medium-pressure steam enters the external heat supply and power generation system through a pipeline as a product. After the cooled carbon dioxide-rich flue gas is dust-removed by a dust collector, a part of it enters the gasification combustion unit and the combustion heat exchange unit respectively for recycling, and the other part goes to the cooling and compression unit through a pipeline.

[0022] S4: The carbon dioxide-rich flue gas obtained in step S3 is mixed with the oxygen supplemented from the outside and enters the cooling and compression unit through a pipeline to be pressurized, obtaining compressed carbon dioxide-rich flue gas with a pressure of 0.8 - 0.9 MPaG and a temperature of 32 - 40 °C and wastewater. Among them, the wastewater enters the external wastewater treatment system through a pipeline.

[0023] S5: The compressed carbon dioxide-rich flue gas obtained in step S4 enters the hydrocarbon and sulfur removal unit through a pipeline for impurity removal, removing most of the hydrocarbons and sulfur-containing impurities in the compressed carbon dioxide-rich flue gas to obtain purified carbon dioxide-rich flue gas with a total hydrocarbon content of less than 10 ppm and a total sulfur content of less than 0.1 ppm.

[0024] S6: The purified carbon dioxide-rich flue gas obtained in step S5 is pressurized to 2.6 - 3 MPaG by a secondary compressor and then enters a dehydration and drying unit for water removal; the dehydration and drying unit adopts a three-column adsorption process to obtain a dried carbon dioxide-rich flue gas with a water content of less than 20 ppm.

[0025] S7: The dried carbon dioxide-rich flue gas obtained in step S6 enters the liquefaction and purification unit through a pipeline; the dried carbon dioxide-rich flue gas exchanges heat and cools with the gas at the top of the purification column in the liquefaction and purification unit, and then is heated by a reboiler and separated in the purification column to remove light components such as oxygen, nitrogen, and methane to obtain a regenerated gas; the regenerated gas is refluxed to the dehydrodesulfurization unit, mixed with dry air, and then heated by an electric heater in the dehydrodesulfurization unit for heating and regeneration of the drying tower in the dehydration and drying unit; the gas from which the light components are removed is throttled and cooled at the top of the purification column and further liquefied by the cold energy provided by a refrigeration ice machine to obtain a high-value food-grade carbon dioxide liquid product with a carbon dioxide purity of 99.9 vol%, which enters an external carbon dioxide liquid storage tank for filling vehicles and external transportation.

[0026] The present invention has the following beneficial effects compared with the prior art:

[0027] (1) The system provided by the present invention has low requirements for the quality of raw bamboo and a simple treatment process, which not only solves the problem of the disposal of waste materials in the bamboo processing process but also realizes the utilization of waste.

[0028] (2) The system provided by the present invention can avoid environmental pollution problems caused by direct combustion emissions of CO 2 , NO x , SO 2 and dust.

[0029] (3) The system provided by the present invention realizes the full utilization of bamboo waste resources and produces high-value heat gas, biomass carbon powder, medium-temperature and medium-pressure steam, and food-grade carbon dioxide liquid products. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flow chart of the bamboo waste hierarchical combustion carbon-thermal-electricity-carbon co-production system provided in this embodiment;

[0031] In the figure: gasification combustion unit 1, gas-solid separation unit 2, combustion heat exchange unit 3, cooling and compression unit 4, dehydrodesulfurization unit 5, dehydration and drying unit 6, liquefaction and purification unit 7, secondary compressor 8; carbon dioxide-rich flue gas A, compressed carbon dioxide-rich flue gas B, purified carbon dioxide-rich flue gas C, dried carbon dioxide-rich flue gas D, carbon dioxide liquid E, regenerated gas F. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be further described and explained below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment in the present invention can be combined correspondingly on the premise that there is no conflict with each other.

[0033] As Figure 1 shown, as a preference of the specific embodiment of the present invention, this embodiment provides a bamboo waste hierarchical combustion carbon-thermal-electricity-carbon co-production system. The system includes a gasification combustion unit 1, a gas-solid separation unit 2, a combustion heat exchange unit 3, a cooling compression unit 4, a dehydrodesulfurization unit 5, a dehydration drying unit 6, a liquefaction purification unit 7, and a secondary compressor 8;

[0034] In the system provided in this embodiment, the material inlet of the gasification combustion unit 1 receives bamboo waste from the feeding system, and the gas inlet of the gasification combustion unit 1 receives oxygen-rich gas from the air chamber. After the bamboo waste and the oxygen-rich gas are quickly mixed and heated, the bamboo waste undergoes pyrolysis gasification and combustion reactions to obtain high-temperature gas containing biomass powder particles.

[0035] In this embodiment, a fluidized bed gasifier is used as the core equipment in the gasification combustion unit 1, and the reaction temperature of the fluidized bed gasifier is controlled at 590 - 610 °C. In order to make the combustion more complete, the particle size of the bamboo waste particles provided by the feeding system is controlled at 1 - 20 mm, and the purity of the oxygen-rich gas provided by the air chamber is 90 - 95 vol%.

[0036] In the system provided in this embodiment, the upper outlet of the gasification combustion unit 1 is connected to the inlet of the gas-solid separation unit 2 through a pipeline. The high-temperature gas containing biomass powder particles from the gasification combustion unit 1 undergoes gas-solid separation in the solid separation unit 2 to obtain biomass carbon powder (also known as bamboo charcoal) and hot gas. A primary cyclone dust collector and a secondary cyclone separator are arranged in the gas-solid separation unit 2, which can make the separation more thorough. A hot gas outlet and a biomass carbon powder outlet are also provided on the gas-solid separation unit 2. The biomass carbon powder outlet of the gas-solid separation unit 2 is connected to an external transition carbon bin through a pipeline, and the hot gas outlet is connected to the hot gas inlet of the combustion heat exchange unit 3 through a pipeline.

[0037] In the system provided in this embodiment, the gas inlet of the combustion heat exchange unit 3 receives oxygen-rich gas from the air chamber. In this embodiment, a combustion chamber, a water-cooled wall, an evaporation heating surface, a economizer, an air preheater, and a steam drum are arranged in the combustion heat exchange unit 3. The hot flue gas from the gas-solid separation unit 2 and the oxygen-rich gas further burn and release heat in the combustion chamber to obtain high-temperature carbon dioxide-rich flue gas. After the high-temperature carbon dioxide-rich flue gas exchanges heat with the water-cooled wall, the evaporation heating surface, the economizer, and the air preheater, medium-temperature and medium-pressure steam products and carbon dioxide-rich flue gas A are obtained. A steam outlet and a carbon dioxide-rich flue gas outlet are also provided on the combustion heat exchange unit 3. The steam outlet of the combustion heat exchange unit 3 is connected to external equipment through a pipeline. At this time, the temperature of the steam product is 420-480 °C, and the pressure is 3.6-4.0 MPaG, which can be used for heating or power generation. At this time, the temperature of the carbon dioxide-rich flue gas A is 130 °C. The carbon dioxide-rich flue gas outlet of the combustion heat exchange unit 3 is divided into three branches after passing through a pipeline equipped with a dust collector. The first branch enters the cooling and compression unit 4 through a pipeline, and the second and third branches return to the combustion heat exchange unit 3 and the gasification combustion unit 1 through pipelines respectively.

[0038] In the system provided in this embodiment, the carbon dioxide-rich flue gas A from the combustion heat exchange unit 3 is compressed and cooled in the cooling and compression unit 4 to obtain compressed carbon dioxide-rich flue gas B. A waste water outlet and a compressed carbon dioxide-rich flue gas outlet are also provided on the cooling and compression unit 4. The waste water outlet of the cooling and compression unit 4 is connected to the external waste water treatment system through a pipeline, and the compressed carbon dioxide-rich flue gas outlet is connected to the hydrocarbon and sulfur removal unit 5 through a pipeline. The pressure of the compressed carbon dioxide-rich flue gas B obtained after the cooling and compression unit 4 is in the range of 0.8-0.9 MPaG, and the temperature is between 32-40 °C.

[0039] In the system provided in this embodiment, the hydrocarbon and sulfur removal unit 5 includes a heat exchanger, an electric heater, a hydrocarbon removal reactor, a scrubbing tower, and a sulfur dioxide adsorption tower. Among them, a sulfur hydrocarbon conversion catalyst is loaded in the hydrocarbon removal reactor, a dehydration adsorbent and a purification adsorbent are loaded in the scrubbing tower, and a sulfur dioxide adsorbent is installed in the sulfur dioxide adsorption tower. The compressed carbon dioxide-rich flue gas B from the cooling and compression unit 4 removes most of the hydrocarbons and sulfur-containing impurities in the hydrocarbon and sulfur removal unit 5 to obtain purified carbon dioxide-rich flue gas C. A waste water outlet and a purified carbon dioxide-rich flue gas outlet are also provided on the hydrocarbon and sulfur removal unit 5. The waste water outlet of the hydrocarbon and sulfur removal unit 5 is connected to the external waste water treatment system through a pipeline. The purified carbon dioxide-rich flue gas outlet of the hydrocarbon and sulfur removal unit 5 is compressed again by a two-stage compressor 8 and then connected to the dehydration and drying unit 6.

[0040] In the system provided by this embodiment, the dehydration and drying unit 6 adopts a three-tower adsorption process. During normal operation, one drying tower adsorbs moisture, one drying tower is in the drying stage, and the other drying tower is in the cooling stage. The three drying towers switch jobs periodically to achieve continuous drying of the purified carbon dioxide-rich flue gas C; the dried carbon dioxide-rich flue gas D obtained after passing through the dehydration and drying unit 6 has a water content of less than 20 ppm. A dried carbon dioxide-rich flue gas outlet is provided on the dehydration and drying unit 6, and the dried carbon dioxide-rich flue gas outlet is connected to the liquefaction and purification unit 7 through a pipeline.

[0041] In the system provided by this embodiment, the liquefaction and purification unit 7 includes a purification tower, a throttle valve, a refrigeration ice machine, a reboiler, and a condenser. Among them, the refrigeration ice machine is a closed refrigeration cycle system, and the refrigeration ice machine and the self-throttling of the dried carbon dioxide-rich flue gas D after removing light components jointly provide the refrigeration capacity required for carbon dioxide liquefaction. A regeneration gas outlet and a carbon dioxide liquid outlet are also provided on the liquefaction and purification unit 7. The regeneration gas outlet of the liquefaction and purification unit 7 returns to the dehydration and drying unit 6 through a pipeline for recycling. The carbon dioxide liquid outlet of the liquefaction and purification unit 7 is connected to an external carbon dioxide liquid storage tank through a pipeline to recover the food-grade carbon dioxide liquid E product. The purity of the carbon dioxide liquid E obtained after passing through the liquefaction and purification unit 7 is not less than 99.9 vol%, and it can be used as the food-grade carbon dioxide liquid E product

[0042] This embodiment also provides a method for co-producing bamboo waste hierarchical combustion carbon, heat, and electricity using the above system, and the specific steps are as follows:

[0043] S1: The bamboo waste from the feeding system enters the fluidized bed gasifier of the gasification and combustion unit 1, and after being mixed and heated with the oxygen-rich gas in the air chamber, pyrolysis gasification and combustion reactions occur to obtain a high-temperature gas containing biomass carbon powder; the high-temperature gas containing biomass carbon powder goes to the gas-solid separation unit 2 through a pipeline;

[0044] S2: The high-temperature gas containing biomass carbon powder obtained in step S1 enters the gas-solid separation unit 2 through a pipeline. The gas-solid separation unit 2 includes a primary separation process and a secondary separation process; the high-temperature gas containing biomass carbon powder passes through a primary cyclone dust collector and a secondary cyclone separator to obtain hot flue gas and biomass carbon powder (bamboo charcoal); among them, the biomass carbon powder enters the transition carbon bin as a product through a pipeline; the hot flue gas goes to the combustion heat exchange unit 3 through a pipeline;

[0045] S3: The hot flue gas obtained in step S2 enters the combustion heat exchange unit 3 through a pipeline for further combustion and heat release, resulting in high-temperature steam and high-temperature carbon dioxide-rich flue gas. The high-temperature carbon dioxide-rich flue gas exchanges heat with the water wall, evaporative heating surface, economizer, and air preheater to obtain medium-temperature and medium-pressure steam and cooled carbon dioxide-rich flue gas A. Among them, the medium-temperature and medium-pressure steam product enters the external heating and power generation system as a heating and power generation product. After the cooled carbon dioxide-rich flue gas A is dust-removed by a dust collector, a part of it enters the fluidized bed gasifier and the combustion heat exchange unit 3 for recycling, and the other part goes to the cooling and compression unit 4 through a pipeline.

[0046] S4: A part of the dust-removed and cooled carbon dioxide-rich flue gas A obtained in step S3 is mixed with the oxygen supplemented from the outside and enters the cooling and compression unit 4 through a pipeline for pressurization to obtain compressed carbon dioxide-rich flue gas B with a pressure in the range of 0.8 - 0.9 MPaG and a temperature in the range of 32 - 40 °C and wastewater. Among them, the wastewater enters the external wastewater treatment system through a pipeline. The compressed carbon dioxide-rich flue gas B goes to the hydrocarbon and sulfur removal unit 5 through a pipeline.

[0047] S5: The compressed carbon dioxide-rich flue gas B obtained in step S4 enters the hydrocarbon and sulfur removal unit 5 for impurity removal to remove most of the hydrocarbons and sulfur-containing impurities in the compressed carbon dioxide-rich flue gas B, obtaining purified carbon dioxide-rich flue gas C with a total hydrocarbon content of less than 10 ppm and a total sulfur content of less than 0.1 ppm.

[0048] S6: The purified carbon dioxide-rich flue gas C obtained in step S5 is pressurized to 2.6 - 3 MPaG through secondary compression and enters the dehydration and drying unit 6 for water removal. The dehydration and drying unit 6 adopts a method of periodically switching drying towers to ensure that the moisture content of the system is qualified, obtaining dried carbon dioxide-rich flue gas D with a flue gas moisture content of less than 20 ppm.

[0049] S7: The dried carbon dioxide-rich flue gas D obtained in step S6 enters the liquefaction and purification unit 7 through a pipeline. After the dried carbon dioxide-rich flue gas D is heat-exchanged and cooled with the gas at the top of the purification tower and then heated by a reboiler, it is separated in the purification tower to remove light components such as oxygen, nitrogen, and methane, obtaining a regeneration gas F. The regeneration gas F is mixed with dried air and heated by the electric heater of the hydrocarbon and sulfur removal unit 5 for the heating regeneration of the drying tower. The gas from which the light components are removed is throttled and cooled at the top of the purification tower and further liquefied by the cold energy provided by a refrigeration ice machine to obtain a high-value food-grade carbon dioxide liquid E product with a carbon dioxide purity of 99.9 vol%, which enters the external carbon dioxide liquid storage tank for filling vehicles and external transportation.

[0050] The embodiments described above are only a preferred solution of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A bamboo waste graded combustion charcoal heat and power cogeneration system, characterized in that: It comprises a gasification and combustion unit (1), a gas-solid separation unit (2), a combustion and heat exchange unit (3), a cooling and compression unit (4), a dehydrogenation and desulfurization unit (5), a dehydration and drying unit (6) and a liquefaction and purification unit (7); The material inlet of the gasification and combustion unit (1) receives bamboo waste from the feeding system, and the gas inlet of the gasification and combustion unit (1) receives oxygen-rich gas from the wind chamber; the upper outlet of the gasification and combustion unit (1) is connected to the inlet of the gas-solid separation unit (2) through a pipeline; The hot gas outlet of the gas-solid separation unit (2) is connected to the hot gas inlet of the combustion heat exchange unit (3) through a pipeline; the gas inlet of the combustion heat exchange unit (3) receives oxygen-rich gas from the wind chamber; the carbon dioxide-rich flue gas outlet of the combustion heat exchange unit (3) is divided into three branches after passing through a pipeline provided with a dust collector, the first branch enters the cooling and compression unit (4) through a pipeline, and the second branch and the third branch return to the combustion heat exchange unit (3) and the gasification combustion unit (1) through pipelines respectively; The compressed carbon dioxide-rich flue gas outlet of the cooling and compression unit (4) is connected to the dehydrogenation and desulfurization unit (5) through a pipeline; the purified carbon dioxide-rich flue gas outlet of the dehydrogenation and desulfurization unit (5) is compressed again by a secondary compressor (8) and then connected to the dehydration and drying unit (6); the dried carbon dioxide-rich flue gas outlet of the dehydration and drying unit (6) is connected to the liquefaction and purification unit (7) through a pipeline; the regenerated gas outlet of the liquefaction and purification unit (7) is returned to the dehydration and drying unit (6) through a pipeline for recycling; the carbon dioxide liquid outlet of the liquefaction and purification unit (7) is connected to an external carbon dioxide liquid storage tank through a pipeline to recover food-grade carbon dioxide liquid products.

2. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1 is characterized in that: The gas-solid separation unit (2) is also provided with a biomass carbon powder outlet, and the biomass carbon powder outlet of the gas-solid separation unit (2) is connected to an external transition carbon bin through a pipeline; the combustion heat exchange unit (3) is also provided with a steam outlet, and the steam outlet of the combustion heat exchange unit (3) is connected to external equipment through a pipeline for heating or power generation; the cooling and compression unit (4) is also provided with a wastewater outlet, and the wastewater outlet of the cooling and compression unit (4) is connected to an external wastewater treatment system through a pipeline; the dehydrogenation and desulfurization unit (5) is also provided with a wastewater outlet, and the wastewater outlet of the dehydrogenation and desulfurization unit (5) is connected to an external wastewater treatment system through a pipeline.

3. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1 is characterized in that: The gasification and combustion unit (1) adopts a fluidized bed gasification furnace, the reaction temperature is controlled at 590-610° C., the particle size of the received bamboo waste particles is 1-20 mm; the purity of the enriched oxygen provided by the wind chamber is 90-95 vol%.

4. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1, characterized in that: The gas-solid separation unit (2) comprises a primary cyclone dust collector and a secondary cyclone separator.

5. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1, characterized in that: The combustion heat exchange unit (3) comprises a combustion chamber, a water-cooled wall, an evaporative heating surface, an economizer, an air preheater and a steam drum; the hot fuel gas and the oxygen-rich gas from the gas-solid separation unit (2) are burned and released heat in the combustion chamber, and then heat exchanged through the water-cooled wall, the evaporative heating surface, the economizer and the air preheater to obtain a steam product and carbon dioxide-rich flue gas; the temperature of the steam product is 420-480° C. and the pressure is 3.6-4.0 MPaG; the temperature of the carbon dioxide-rich flue gas is 130° C.

6. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1, characterized in that: The compressed carbon dioxide-rich flue gas obtained after passing through the cooling and compression unit (4) has a pressure in the range of 0.8 to 0.9 MPaG and a temperature in the range of 32 to 40°C.

7. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1, characterized in that: The dehydrocarbon desulfurization unit (5) comprises a heat exchanger, an electric heater, a dehydrocarbon reactor, a washing tower and a sulfur dioxide adsorption tower; the dehydrocarbon reactor is filled with a sulfur hydrocarbon conversion catalyst; the washing tower is filled with a dehydration adsorbent and a purification adsorbent; and the sulfur dioxide adsorption tower is filled with a sulfur dioxide adsorbent.

8. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1, characterized in that: The dehydration and drying unit (6) adopts a three-tower adsorption process. During normal operation, one drying tower performs moisture adsorption, one drying tower is in a drying stage, and another drying tower is in a cooling stage. The three drying towers are periodically switched to achieve continuous drying of the purified carbon dioxide-rich flue gas. The water content of the dried carbon dioxide-rich flue gas obtained by the dehydration and drying unit (6) is less than 20 ppm.

9. The bamboo waste graded combustion charcoal heat and power cogeneration system according to claim 1, characterized in that: The liquefaction and purification unit (7) comprises a purification tower, a throttle valve, a refrigeration ice machine, a reboiler and a condenser; the refrigeration ice machine is a closed refrigeration cycle system; the purity of the carbon dioxide liquid obtained by the liquefaction and purification unit (7) is not less than 99.9 vol%.

10. A method for cogeneration of heat, electricity and carbon from bamboo waste by graded combustion using the system described in any one of claims 1 to 9, characterized in that: The details are as follows: S1: After the bamboo waste from the feeding system enters the gasification and combustion unit (1), it is mixed and heated with the oxygen-rich air from the wind chamber, and pyrolysis, gasification and combustion reactions occur to obtain high-temperature gas containing biomass charcoal powder; S2: The high-temperature gas containing biomass carbon powder obtained in step S1 enters the gas-solid separation unit (2) through a pipeline; the high-temperature gas containing biomass carbon powder passes through the primary separation process and the secondary separation process in the gas-solid separation unit (2) to obtain hot gas and biomass carbon powder; wherein the biomass carbon powder enters the transition carbon bin as a product through a pipeline; S3: The hot fuel gas obtained in step S2 enters the combustion heat exchange unit (3) through a pipeline to further burn and release heat to obtain high-temperature steam and high-temperature carbon dioxide-rich flue gas, and exchanges heat with the water-cooled wall, evaporation heating surface, economizer, and air preheater in the combustion heat exchange unit (3) to obtain medium-temperature medium-pressure steam and cooled carbon dioxide-rich flue gas (A); wherein the medium-temperature medium-pressure steam is connected to the external heating and power generation system through a pipeline as a product; after the cooled carbon dioxide-rich flue gas (A) is dedusted by a dust collector, a part of it enters the gasification combustion unit (1) and the combustion heat exchange unit (3) for recycling, and the other part of it goes to the cooling compression unit (4) through a pipeline; S4: The carbon dioxide-rich flue gas (A) obtained in step S3 is mixed with oxygen supplemented from the outside and enters the cooling and compression unit (4) through a pipeline for pressurization to obtain compressed carbon dioxide-rich flue gas (B) with a pressure of 0.8-0.9 MPaG and a temperature of 32-40° C. and wastewater; wherein the wastewater enters an external wastewater treatment system through a pipeline; S5: The compressed carbon dioxide-rich flue gas (B) obtained in step S4 enters the dehydrogenation and desulfurization unit (5) through a pipeline to remove impurities, remove most of the hydrocarbons and sulfur-containing impurities in the compressed carbon dioxide-rich flue gas (B), and obtain a purified carbon dioxide-rich flue gas (C) with a total hydrocarbon content of less than 10 ppm and a total sulfur content of less than 0.1 ppm; S6: The purified carbon dioxide-rich flue gas (C) obtained in step S5 is pressurized to 2.6-3 MPaG by a secondary compressor (8) and then enters a dehydration drying unit (6) for dehydration; the dehydration drying unit (6) adopts a three-tower adsorption process to obtain dry carbon dioxide-rich flue gas (D) with a water content of less than 20 ppm; S7: The dry carbon dioxide-rich flue gas (D) obtained in step S6 enters the liquefaction and purification unit (7) through a pipeline; the dry carbon dioxide-rich flue gas (D) is cooled by heat exchange with the gas at the top of the purification tower in the liquefaction and purification unit (7), and then heated by a reboiler and separated in the purification tower to remove light components such as oxygen, nitrogen and methane to obtain a regenerated gas (F); the regenerated gas (F) is refluxed to the dehydrogenation and desulfurization unit (5), mixed with dry air, and then heated by an electric heater in the dehydrogenation and desulfurization unit (5) and used for heating and regeneration of the drying tower in the dehydration and drying unit (6); the gas from which the light components have been removed is throttled and cooled at the top of the purification tower, and is further liquefied by the cold provided by a refrigeration ice machine to obtain a high-value-added food-grade carbon dioxide liquid (E) product with a carbon dioxide purity of 99.9 vol%, which enters an external carbon dioxide liquid storage tank for filling vehicles for external transmission.

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