Carbon dioxide capture and rich carbon dioxide preparation system and method based on carbonate cycle

Abstract

The invention discloses a system and a method for capturing carbon dioxide and preparing rich carbon dioxide based on carbonate circulation, and relates to the technical field of carbon capturing and resource utilization and industrial process gas treatment. The system comprises a carbon dioxide-containing gas supply unit, a carbonate circulation carbon capture unit, a carbon dioxide purification unit and a heat energy integration and control unit. The carbonate circulating carbon capturing unit forms a solid closed cycle by an absorption reactor, a regeneration reactor and a solid conveying device, and is provided with a gas locking structure to reduce gas streaming; the system is provided with a particle grading and fine powder recycling branch for recycling pulverized particles and back-doping or discharging inactivated solids; the heat energy integration unit recycles regeneration waste heat and carries out energy redistribution through the heat carrier loop. According to the system, CO2-rich stable output can be realized, the energy consumption is reduced, and the operation reliability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon capture and resource utilization and industrial process gas treatment, in particular to a carbon dioxide capture and carbon dioxide enrichment preparation system and method based on carbonate cycle. BACKGROUND

[0002] In the steel, coking, cement, lime kiln, chemical and waste incineration industries, the amount of carbon dioxide containing tail gas / flue gas emission is large and the composition fluctuates obviously. In the existing carbon dioxide capture technology, the solvent absorption such as amine method has problems such as solvent degradation, corrosion, high energy consumption and complex operation and maintenance; the cost and stability of physical absorption, membrane separation and other processes are limited under low partial pressure or high impurity conditions.

[0003] Based on the solid absorption-regeneration route of carbonate cycle reaction (such as CaCO3 / CaO cycle), the solid absorption-regeneration route has the advantages of wide source of absorbent, high temperature resistance and potential low cost, but in engineering application, it still faces the following problems: ① Insufficient solid cycle and gas isolation leads to cross flow and affects CO2 enrichment; ② Solid pulverization causes fine powder entrainment, plugging and system instability; ③ Fluctuation of raw gas impurities (acidic gas, moisture, dust) makes it difficult to match the purification energy consumption and process; ④ Insufficient coupling of heat release / absorption and downstream heat utilization, low overall energy efficiency; ⑤ Lack of online monitoring and linkage control leads to weak stable output ability of CO2-rich gas.

[0004] Therefore, it is necessary to propose a system and method which can realize solid closed cycle, fine powder classification recovery and heat energy integrated linkage control without sacrificing the protection scope, so as to improve the CO2-rich raw gas quality and the long-term stable operation ability of the system.

[0005] Therefore, how to develop a carbon dioxide capture and carbon dioxide enrichment preparation system and method based on carbonate cycle which can be industrialized is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0006] Therefore, the present application provides a carbon dioxide capture and carbon dioxide enrichment preparation system and method based on carbonate cycle.

[0007] A carbon dioxide capture and carbon dioxide enrichment preparation system based on carbonate cycle, comprising: a carbon dioxide containing gas providing unit, a carbonate cycle carbon capture unit, a carbon dioxide purification unit and a heat energy integration and control unit; The carbonate cycle carbon capture unit comprises: an absorption reactor, a regeneration reactor, a first solid conveying device and a second solid conveying device; the absorption reactor is filled with a solid adsorbent, the solid outlet of the absorption reactor is connected with the solid inlet of the regeneration reactor through the first solid conveying device, and the solid outlet of the regeneration reactor is connected with the solid inlet of the absorption reactor through the second solid conveying device; The carbon dioxide-containing gas providing unit, the absorption reactor, the regeneration reactor and the carbon dioxide purification unit are sequentially connected along the gas flow by pipelines; The heat energy integration and control unit comprises at least one heat exchange device for recycling at least part of the heat of the regeneration reactor. The heat exchange device is preferably arranged in the high-temperature flue gas outlet of the decomposition unit or the subsequent pipeline thereof, for transferring the waste heat to the inlet gas of the absorption unit, the process heating medium or the hot carrier oil system, but is not limited to the above structural form.

[0008] Further, the heat energy integration and control unit comprises a heat exchanger I, and the flue gas outlet of the regeneration reactor is provided with the heat exchanger I for integrated utilization of the waste heat of the regeneration reactor.

[0009] Further, the carbon dioxide-containing gas providing unit comprises a carbon dioxide-containing gas inlet pipeline and a dust remover, the carbon dioxide-containing gas inlet pipeline is provided with a heat exchanger IV, the carbon dioxide-containing gas inlet pipeline, the dust remover and the absorption reactor are sequentially connected by pipelines, and the carbon dioxide-containing flue gas or process gas in the carbon dioxide-containing gas inlet pipeline comes from a combustion device, an industrial furnace, a boiler tail gas, a cement kiln tail gas, a steelmaking / blast furnace gas purification tail gas, a chemical tail gas or a waste incineration flue gas.

[0010] Further, the absorption reactor is a fluidized bed carbon capture absorption tower, a moving bed carbon capture absorption tower, a bubbling bed carbon capture absorption tower or a rotary kiln carbon capture absorption tower. The regeneration reactor is a rotary kiln, a fluidized bed furnace, a shaft kiln or an electric heating furnace; and the heat supply mode of the regeneration reactor is one or a combination of several of external fuel, electric heating, oxygen-enriched combustion or hot carrier circulation.

[0011] The carbonate cycle carbon capture unit selects calcium carbonate cycle decomposition to capture carbon dioxide, the first solid conveying device comprises a first elevator and a first conveying belt, the second solid conveying device comprises a second elevator and a second conveying belt, the solid outlet of the absorption reactor is sequentially connected with the solid inlet of the regeneration reactor through the first elevator and the first conveying belt, and the solid outlet of the regeneration reactor is sequentially connected with the solid inlet of the absorption reactor through the second elevator and the second conveying belt.

[0012] Further, the carbon dioxide purification unit comprises a pre-cooling and dust removal device, a washing or deacidification device, a drying and adsorption device, a desulfurization device and a compression and pressure regulation device I; The pre-cooling and dust removal device comprises a heat exchanger V or a condenser, and a cyclone separator I, a bag-type dust collector or an electric dust collector; The washing or deacidification device is a washing tower or a gas washing tower; The drying and adsorption device comprises a compressor one, a molecular sieve or activated alumina dryer one, and an activated carbon adsorber one or adsorption tower; The desulfurization device is a desulfurization tower or an alkali washing tower. The compression and pressure regulating device one is a compressor two or a pressure regulating valve. The regeneration reactor, the cyclone separator one, the bag filter or the electric dust collector, the washing tower or the gas washing tower, the compressor one, the molecular sieve or activated alumina dryer one, the activated carbon adsorber one or adsorption tower, the desulfurization tower or the alkali washing tower, and the compressor two or the pressure regulating valve are connected in sequence through pipelines, and a heat exchanger five or a condenser is arranged on the pipeline connecting the regeneration reactor and the cyclone separator one, the bag filter or the electric dust collector.

[0013] Further, the solid adsorbent comprises one or a combination of CaO, MgO, SrO, BaO, red mud activated adsorbent, or steel slag activated adsorbent, and preferably CaO.

[0014] Further, the activation treatment of the red mud activated adsorbent and / or the steel slag activated adsorbent comprises calcination, hydration, and / or mechanical activation. These solid adsorbents belong to alkaline earth metal oxides or calcium-containing active phase solid waste which can be carbonated and regenerated; the purpose of activation (calcination / hydration / mechanical activation) is to improve the pore structure, disperse the active phase, and improve the cycle attenuation; different materials correspond to different optimal windows (for example, the regeneration temperature can be moved up / down). The above-mentioned adsorbents all belong to alkaline earth metal oxides or calcium / magnesium-containing active phase industrial by-product adsorption materials which have carbonation-decomposition reversible characteristics and can be recycled.

[0015] Further, the absorption reactor is further connected with an adsorbent supplement branch and / or an inactivated solid discharge branch.

[0016] Further, a system monitoring and intelligent control unit is further included, the system monitoring and intelligent control unit adopts a PLC or DCS system, and the PLC or DCS control system is connected with the carbon dioxide-containing gas providing unit, the carbonate cycle carbon capture unit, the carbon dioxide purification unit, and the heat energy integration and control unit through signal lines and / or industrial buses. The monitoring and control system adopts an industrial control system (such as a PLC or DCS), performs online monitoring and interlocking control on temperature, pressure, flow, CO2 concentration, and the like, and realizes stable operation of the absorption and decomposition process.

[0017] The beneficial effects of the above further technical solutions are as follows: the system monitoring and intelligent control unit is set as an independent control module, system monitoring and intelligent control are adopted, multi-source CO2 and multi-working condition operation are adapted, the CO2 load and solid cycle are monitored and controlled in real time through the system monitoring and intelligent control unit, and multiple CO2-containing flue gases from different industrial sources can be adapted, and unified capture of multi-source CO2 is realized.

[0018] Further, the system further comprises a gas lock structure arranged at at least one position of the solid conveying pipeline between the absorption reactor and the regeneration reactor; preferably, the gas lock structure is arranged at the connection between the solid outlet of the absorption reactor and the first solid conveying device and / or the connection between the solid outlet of the regeneration reactor and the second solid conveying device.

[0019] The gas lock structure adopts one or more structures of a double-valve gas lock device (such as a double-valve lock hopper or a double-valve flap valve), a star-type discharge valve or a double-valve gas lock bin, or a combination thereof, to form a partitioned gas layer during the solid transfer process and reduce gas short circuiting. The above-mentioned gas lock structure is only an optional structure form for realizing the gas locking function, and does not limit the specific structure form.

[0020] Further, the system further comprises a fine powder recovery pipeline and a fine powder recovery device, the fine powder recovery pipeline is connected to the pipeline connecting the regeneration reactor and the heat exchanger or the condenser, and the fine powder recovery pipeline, the fine powder recovery device and the regeneration reactor are sequentially connected through the pipeline. The fine powder recovery pipeline and the fine powder recovery device are used to recover the pulverized particles and back-mix into the absorption reactor and / or discharge the deactivated solids, so as to reduce the accumulation of fine powder, reduce the risk of entrainment and plugging, and improve the stability of solid circulation. The fine powder recovery device can adopt one or more structures of a cyclone separator, a bag-type dust collector, an electric dust collector or a particle trap. The fine powder conveying can be completed by a screw conveyor, a pneumatic conveying device, a conveying belt or other conveying structures capable of realizing closed conveying.

[0021] The application also provides a carbon dioxide capture and carbon dioxide-rich preparation method based on a carbonate cycle, comprising the following steps: 1) using the system, sending flue gas or process gas containing carbon dioxide into the absorption reactor to make the carbon dioxide-containing gas contact with calcium oxide solid to generate carbonate solid; 2) sending the carbonate solid obtained in step 1) into the regeneration reactor to decompose at 750-1100°C to generate calcium oxide solid and carbon dioxide-rich gas; 3) sending the carbon dioxide-rich gas obtained in step 2) into a carbon dioxide purification unit for dust removal, dehydration and / or acid removal treatment to obtain carbon dioxide raw gas; 4) returning the calcium oxide solid obtained in step 2) to the absorption reactor in step 1) for recycling.

[0022] Further, the absorption reactor is operated at 300-700°C, preferably 400-650°C, and more preferably 450-550°C; the calcium oxide solid obtained in step 2) is returned to the absorption reactor in step 1) for recycling for ≥40 times; and the volume fraction of the carbon dioxide raw gas is not less than 90%.

[0023] Compared with the existing CO2 capture and preparation technology, the present application has the following beneficial effects: 1. Low-cost, high-concentration CO2 capture and regeneration: CaO / CaCO3 cycle is used for carbon capture, which avoids the problems of solvent degradation and corrosion compared with amine method and other chemical absorption, and can realize CO2 capture at lower energy consumption, and obtain high-concentration CO2 raw gas through high-temperature decomposition furnace, which is suitable for subsequent utilization.

[0024] 2. Energy cascade utilization and thermal energy closure: The sensible heat source of CaCO3 decomposition exhaust gas is recovered through thermal energy integration and control unit, and is used for other process units, which significantly reduces the need for external heat supply.

[0025] 3. CaO / CaCO3 multiple cycles and material closure: The present application controls the particle size, cycle temperature, residence time and other parameters of CaO / CaCO3 particles, so that the solid adsorbent can maintain acceptable CO2 adsorption capacity in ≥40 times or even more cycles, reduce the frequency of material supplement, and realize material closure and cost optimization of CO2 capture carrier.

[0026] 4. Realize effective isolation of solid material circulation and gas flow field, and improve system stability: The present application sets a gas locking structure in the solid circulation channel between the absorption reactor and the regeneration reactor, so that the gas flow between the two reactors is significantly reduced, the influence of high-temperature and high-concentration gas backflow on equipment and process operation is reduced, and the safety and stability of system operation are improved. At the same time, the problem of reduced carbon dioxide absorption efficiency caused by mutual gas flow is avoided.

[0027] 5. Reduce the risk of scaling and wear through particle classification and fine powder recovery, and improve the continuous operation ability: The present application sets a particle classification and fine powder recovery branch in the solid-gas separation or solid circulation path, which can separate and recover the pulverized particles from the system in time and backmix or discharge, so as to reduce the deposition, scaling and abrasion risk of fine powder in the absorption reactor and the regeneration reactor, reduce the carrying and blocking risk, improve the solid circulation stability and equipment life, and improve the long-term continuous operation ability.

[0028] 6. The system structure has universality and scalability, and is suitable for various CO2-rich gas source scenes: The process system of the present application can adapt to CO2-rich gas sources with different compositions and conditions such as combustion tail gas, industrial tail gas, chemical process tail gas and natural gas purification tail gas, and can realize stable operation through automatic adjustment of purification, thermal energy integration, solid circulation and control strategy, which has good engineering implementability and industrialization popularization value.

[0029] The gas flow between the absorption reactor and the regeneration reactor is reduced by >50% through the air lock structure, the CO2 volume fraction is increased by 8%-15%, and the system operation stability is significantly enhanced; Through particle classification and fine powder recovery branch, the fine powder entrainment is reduced by 20%-60%, and the system plugging and wear risk is reduced; Through the bypass / switching strategy of the purification unit, the overall energy consumption of the purification unit can be reduced by 10%-30% under the premise of ensuring that the gas quality meets the standard; Through heat integration, the external heat source demand of the regeneration heating is reduced by 5%-25%, and the overall thermal efficiency of the system is increased by 3%-18%.

[0030] The above improvement range is derived from the comparison and calculation of engineering accounting and typical working conditions, and the values under different working conditions can vary within a reasonable range, but the technical effects of the present application, such as system stability and energy efficiency improvement, are achieved through the air lock structure, fine powder recovery and heat integration. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a whole structure schematic diagram of the carbon dioxide capture and preparation system based on carbonate cycle; Figure 2 It is a structure schematic diagram of the carbon capture unit of carbonate cycle; Figure 3 It is a structure schematic diagram of the heat integration and control unit; Figure 4 It is a structure schematic diagram of the carbon dioxide containing gas providing unit; Figure 5 It is a structure schematic diagram of the carbon dioxide purification unit; Figure 6 It is a structure schematic diagram of the air lock structure, fine powder recovery pipeline and fine powder recovery device. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0033] The carbon dioxide capture and preparation system based on carbonate cycle includes a carbon dioxide containing gas providing unit, a carbon capture unit of carbonate cycle, a carbon dioxide purification unit and a heat integration and control unit; The carbonate cycle carbon capture unit comprises: an absorption reactor, a regeneration reactor, a first solid conveying device and a second solid conveying device; the absorption reactor is filled with solid adsorbent, the solid outlet of the absorption reactor is connected with the solid inlet of the regeneration reactor through the first solid conveying device, and the solid outlet of the regeneration reactor is connected with the solid inlet of the absorption reactor through the second solid conveying device; The carbon dioxide-containing gas providing unit, the absorption reactor, the regeneration reactor and the carbon dioxide purification unit are sequentially connected along a gas flow through pipelines. The heat energy integration and control unit comprises at least one heat exchange device for recycling at least part of the heat of the regeneration reactor.

[0034] The method comprises the following steps: 1) absorption stage: introducing the CO2-containing flue gas into the carbonate absorption device to perform carbonation at a suitable temperature; 2) conveying and gas locking: conveyed to the decomposition unit through a particle grading and gas locking structure to reduce gas channeling; 3) decomposition and gas production: thermal decomposition under a condition higher than the decomposition temperature to obtain the CO2-rich gas; 4) gas purification and collection: cooling, dust removal, condensation or adsorption to obtain the available CO2-rich gas; 5) cycle regeneration: the oxide after decomposition is returned to the absorption unit for recycling; 6) heat energy integration: heat exchange and recycling by using the flue gas waste heat; The working principle of the present application is that the carbon dioxide-containing gas providing unit is used for providing flue gas or process gas containing carbon dioxide. The carbonate cycle carbon capture unit comprises: The absorption reactor is used for contacting the carbon dioxide-containing gas with calcium oxide solid to generate carbonate solid; The regeneration reactor is used for decomposing the carbonate solid under a high-temperature condition to generate calcium oxide solid and carbon dioxide-rich gas; The first solid conveying device and the second solid conveying device are used for circulating and conveying the calcium oxide and the carbonate solid between the absorption reactor and the regeneration reactor; The carbon dioxide purification unit is used for performing dust removal, dehydration and / or acid removal treatment on the carbon dioxide-rich gas to obtain carbon dioxide raw gas; The heat energy integration and control unit is arranged in the regeneration reactor and is used for recycling at least part of the heat released by the regeneration reactor and supplying heat to other units, so that the cascade utilization and balance of the heat energy of the system are realized.

[0035] In one embodiment, the heat energy integration and control unit comprises a heat exchanger one, and the flue gas outlet of the regeneration reactor is provided with the heat exchanger one, which is used for recycling and utilizing the waste heat of the regeneration reactor.

[0036] In one embodiment, the carbon dioxide gas supply unit comprises a carbon dioxide-containing gas inlet pipeline and a dust remover, the carbon dioxide-containing gas inlet pipeline is provided with a heat exchanger four, the carbon dioxide-containing gas inlet pipeline, the dust remover and the absorption reactor are connected in sequence through pipelines, and the carbon dioxide-containing flue gas or process gas in the carbon dioxide-containing gas inlet pipeline comes from a combustion device, an industrial furnace, a boiler tail gas, a cement kiln tail gas, a steelmaking / blast furnace gas purification tail gas, a chemical tail gas or a waste incineration flue gas.

[0037] The working principle of the carbon dioxide gas supply unit: the carbon dioxide gas supply unit is used for providing carbon dioxide-containing flue gas or process gas, which can come from a combustion device, an industrial furnace, a boiler tail gas, a cement kiln tail gas, a steelmaking / blast furnace gas purification tail gas, a chemical tail gas or a waste incineration flue gas, etc., and is provided with a dust remover and a heat exchanger four for adjusting temperature and removing large-particle dust.

[0038] In one embodiment, the absorption reactor is a fluidized bed carbon capture absorption tower, a moving bed carbon capture absorption tower, a bubbling bed carbon capture absorption tower or a rotary kiln carbon capture absorption tower. The regeneration reactor is a rotary kiln, a fluidized bed furnace, a shaft kiln or an electric heating furnace; and the heat supply mode of the regeneration reactor is one or a combination of several of external fuel, electric heating, oxygen-enriched combustion and hot carrier circulation.

[0039] The carbon dioxide-containing flue gas or process gas in the carbon dioxide-containing gas inlet pipeline comes from a combustion device, an industrial furnace, a boiler tail gas, a cement kiln tail gas, a steelmaking / blast furnace gas purification tail gas, a chemical tail gas or a waste incineration flue gas, etc.

[0040] In one embodiment, the carbon dioxide purification unit comprises a precooling and dust removal device, a washing or deacidification device, a drying and adsorption device, a desulfurization device and a compression and pressure regulation device one. The precooling and dust removal device comprises a heat exchanger five or a condenser, and a cyclone separator one, a bag dust collector or an electric dust collector. The washing or deacidification device is a washing tower or a gas washing tower. The drying and adsorption device comprises a compressor one, a molecular sieve or activated alumina dryer one, and an activated carbon adsorber one or an adsorption tower. The desulfurization device is a desulfurization tower or an alkali washing tower. The compression and pressure regulation device one is a compressor two or a pressure regulating valve. The regeneration reactor, cyclone separator 1, bag filter or electric dust collector, washing tower or gas washing tower, compressor 1, molecular sieve or activated alumina dryer 1, activated carbon adsorber 1 or adsorption tower, desulfurization tower or caustic washing tower, and compressor 2 or pressure regulating valve are connected in sequence through pipelines, and a heat exchanger 5 or condenser is arranged on the pipeline connecting the regeneration reactor and the cyclone separator 1, bag filter or electric dust collector.

[0041] Working principle of the carbon dioxide purification unit: Pre-cooling and dust removal device: After the CO2-rich flue gas is discharged from the regeneration reactor, it is first pre-cooled by the heat exchanger 5 or condenser to condense the water vapor and separate it from the gas, and then the dust and impurities are removed by the cyclone separator 1, bag filter or electric dust collector.

[0042] Washing or deacidification device: After pre-cooling and dust removal, the gas enters the washing tower or gas washing tower, and water or alkaline solution is used for countercurrent spraying to further cool the gas and remove water-soluble impurities and acidic components.

[0043] Drying and adsorption device: After washing, the CO2 gas is appropriately pressurized by the compressor 1 and enters the molecular sieve or activated alumina dryer 1 to remove residual water, and an activated carbon adsorber 1 or adsorption tower is configured according to the composition of the raw gas to remove trace impurities.

[0044] Desulfurization device: For sulfur-containing flue gas, a desulfurization tower or caustic washing tower is provided to remove sulfur dioxide, hydrogen sulfide and other acidic gases.

[0045] Compression and pressure regulation device 1: The purified CO2 gas passes through the compressor 2 or pressure regulating valve to adjust the pressure, so that it reaches the required pressure range for the next reaction.

[0046] Through this combination, the carbon dioxide enrichment and purification unit can complete dust removal, condensation and water removal, deacidification / desulfurization, and pressure adjustment, and output high-purity CO2 raw gas ≥90% that meets the reaction requirements.

[0047] In one embodiment, the solid adsorbent includes one or a combination of CaO, MgO, SrO, BaO, red mud activated adsorbent, or steel slag activated adsorbent.

[0048] The solid adsorbent undergoes a carbonation reaction with the carbon dioxide-containing gas in the carbon capture tower to form the corresponding carbonate solid, and in the decomposition furnace under regeneration conditions, the corresponding oxide is regenerated after the release of the carbon dioxide-rich gas and returns to the carbon capture tower for recycling; the industrial solid waste adsorbent can be treated by calcination, hydration and / or mechanical activation (such as ball milling) to improve the cycling stability.

[0049] In one embodiment, the activation treatment of the red mud activated adsorbent and / or steel slag activated adsorbent includes calcination, hydration and / or mechanical activation.

[0050] In one embodiment, the absorption reactor is also connected with an adsorbent supplement branch and / or an inactivated solid discharge branch.

[0051] In one embodiment, a system monitoring and intelligent control unit is further included, which adopts a PLC or DCS system, and the PLC or DCS control system is connected with the carbon dioxide-containing gas providing unit, the carbonate cycle carbon capture unit, the carbon dioxide purification unit and the heat energy integration and control unit through signal lines and / or industrial buses respectively.

[0052] Working principle of the system monitoring and intelligent control unit: A mass flow meter or a mass flow controller (MFC) is installed on the carbon dioxide-containing gas inlet pipeline to accurately control the CO2 flow, and the flow signal is fed back to the PLC control system or the DCS control system, and a rotation speed sensor or a weight sensor is installed on the circulation pipeline connected with the absorption reactor, the first elevator, the first conveying belt, the regeneration reactor, the second elevator, the second conveying belt and the absorption reactor in the carbonate cycle carbon capture unit to monitor the circulation amount.

[0053] A thermocouple or a Pt100 thermometer and a pressure transmitter are arranged in sequence on the heat conduction carrier pipeline of the regeneration reactor and heat exchangers one, four and five for monitoring temperature and pressure changes.

[0054] A pH sensor is arranged on the circulation liquid pipeline of the washing tower or the gas washing tower for controlling the addition of the deacidifying agent.

[0055] Pneumatic or electric regulating valves are arranged on each pipeline of the carbon dioxide capture and carbon dioxide-rich preparation system for regulating the CO2 and heat conduction oil flow.

[0056] The mass flow meter or the mass flow controller, the rotation speed sensor or the weight sensor, the thermocouple or the Pt100 thermometer, the pressure transmitter, the pH sensor and the pneumatic or electric regulating valve are electrically connected with the PLC or DCS control system respectively.

[0057] The present application can realize: ① automatically adjusting the CaO / CaCO3 material circulation amount according to the CO2 concentration or the flue gas flow; ② adjusting the CO2 flow in real time; ③ adjusting the heat conduction oil flow according to the energy balance to ensure the system heat balance and the reactor temperature stability. Through the above-mentioned equipment composition and connection relationship, the system monitoring and intelligent control unit can obtain key data such as CO2 content, flow, temperature, pressure and CaO / CaCO3 circulation amount in real time, and output control instructions through the PLC / DCS to realize the linkage adjustment and energy optimization of each unit.

[0058] In one embodiment, a gas lock structure is further included, which is arranged at at least one position of the solid conveying pipeline between the absorption reactor and the regeneration reactor; in one embodiment, the gas lock structure is arranged at the connection between the solid outlet of the absorption reactor and the first solid conveying device and / or the connection between the solid outlet of the regeneration reactor and the second solid conveying device.

[0059] The gas lock structure adopts one or more structures of a double-valve gas lock device (such as a double-valve lock hopper or a double-valve flap valve), a star-type discharge valve or a double-valve gas lock bin, or a combination thereof, to form a partitioned gas layer during the solid transfer process and reduce gas short circuiting. The above-mentioned gas lock structure is only an optional structure form for realizing the gas lock function, and does not limit the specific structure form.

[0060] In one embodiment, a fine powder recovery pipeline and a fine powder recovery device are further included, the fine powder recovery pipeline is connected with the pipeline connecting the regeneration reactor and the heat exchanger or the condenser, and the fine powder recovery pipeline, the fine powder recovery device and the regeneration reactor are sequentially connected through the pipeline. The fine powder recovery pipeline and the fine powder recovery device are used to recover the pulverized particles and re-mix them into the absorption reactor and / or discharge the deactivated solids, so as to reduce the accumulation of fine powder, reduce the risk of entrainment and plugging, and improve the stability of solid circulation. The fine powder recovery device can adopt one or more structures of a cyclone separator, a bag-type dust collector, an electric dust collector or a particle trap. The fine powder conveying can be completed by a screw conveyor, a pneumatic conveying device, a conveying belt or other conveying structures capable of realizing closed conveying.

[0061] The method for preparing carbon dioxide-rich carbon dioxide capture and preparation based on carbonate cycle, comprising the following steps: 1) The flue gas or process gas containing carbon dioxide is sent into the absorption reactor by using the system of the present application, so that the gas containing carbon dioxide is contacted with calcium oxide solid to generate carbonate solid; 2) The carbonate solid obtained in step 1) is sent into the regeneration reactor to decompose at 750-1100℃ to generate calcium oxide solid and carbon dioxide-rich gas; 3) The carbon dioxide-rich gas obtained in step 2) is sent into a carbon dioxide purification unit for dust removal, dehydration and / or acid removal treatment to obtain carbon dioxide raw gas; 4) The calcium oxide solid obtained in step 2) is returned to the absorption reactor in step 1) for recycling.

[0062] In one embodiment, the absorption reactor is operated at 300-700℃; the calcium oxide solid obtained in step 2) is returned to the absorption reactor in step 1) for recycling for ≥40 times; the volume fraction of the carbon dioxide raw gas is not less than 90%.

[0063] In one embodiment, the absorption reactor is operated at 400-650℃; In one embodiment, the absorption reactor is operated at 450-550℃; Example 1 The carbon dioxide capture and carbon dioxide-rich preparation method based on the carbonate cycle comprises the following steps: 1) Using the system of the present application, the CO2 volume fraction in the flue gas discharged by a certain coal-fired boiler is 12%, and the temperature is 150℃. The flue gas containing carbon dioxide is sent into the absorption reactor, and the absorption reactor is operated at 550℃(±5℃). The carbon dioxide-containing gas is brought into contact with the calcium oxide solid to generate a carbonate solid; 2) The carbonate solid obtained in step 1) is sent into the regeneration reactor, and is decomposed at 850-900℃ to generate a calcium oxide solid and a carbon dioxide-rich gas; 3) The carbon dioxide-rich gas obtained in step 2) is sent into the carbon dioxide purification unit for dust removal, dehydration and acid removal treatment to obtain carbon dioxide raw gas, and the volume fraction of the carbon dioxide raw gas is ≥90%; 4) The calcium oxide solid obtained in step 2) is returned to the absorption reactor in step 1) for recycling for ≥40 times.

[0064] Example 2 The carbon dioxide capture and carbon dioxide-rich preparation method based on the carbonate cycle comprises the following steps: 1) Using the system of the present application, there are A and B two routes of flue gas containing CO2 in a certain combined plant: A route: cement kiln tail gas, CO2 volume fraction 20%, temperature 280℃; B route: blast furnace gas purification tail gas, CO2 volume fraction 25%, temperature 120℃. The flue gas of A route and B route is mixed in a certain proportion, the flue gas containing carbon dioxide is sent into the absorption reactor, and the absorption reactor is operated at 540℃(±5℃). The carbon dioxide-containing gas is brought into contact with the calcium oxide solid to generate a carbonate solid; 2) The carbonate solid obtained in step 1) is sent into the regeneration reactor, and is decomposed at 900-950℃ to generate a calcium oxide solid and a carbon dioxide-rich gas; 3) The carbon dioxide-rich gas obtained in step 2) is sent into the carbon dioxide purification unit for dust removal, dehydration and / or acid removal treatment to obtain carbon dioxide raw gas, and the volume fraction of the carbon dioxide raw gas is ≥90%; 4) The calcium oxide solid obtained in step 2) is returned to the absorption reactor in step 1) for recycling for ≥40 times.

[0065] Through the present embodiment, the unified capture of multi-source CO2 can be realized; Through the experimental running results of Example 1 and Example 2, the "CaCO3 / CaO cycle-based" proposed in the application has achieved remarkable technical effects in terms of CO2 capture efficiency, regenerated CO2 purity, energy utilization rate and system stability, and the specific performances are as follows: 1. The high-purity CO2 regeneration capacity is significantly improved.

[0066] In Example 1, the regeneration reactor operates at 850-900℃, and the purity of the produced CO2 raw gas reaches more than 90%. This shows that the CaCO3 / CaO cycle-based carbon capture method of the application can effectively convert low-concentration flue gas (CO2≈12%) into high-purity raw gas, which is superior to the limitation of traditional adsorption and membrane separation processes on the concentration of raw gas.

[0067] 2. The CaO adsorbent can realize stable circulation for 30-80 times.

[0068] Example 1 and Example 2 show that CaO still maintains acceptable adsorption activity under the conditions of ≥40 cycles (Example 1) and ≥40 cycles (Example 2). This proves that the temperature window, residence time and cycle control strategy proposed in the application effectively delay the activity decay of CaO, realizing the material closed-loop circulation of the adsorbent.

[0069] 3. The CO2 capture efficiency adapts to different working conditions and multi-source flue gas.

[0070] Through the particle grading + multi-stage gas locking structure between the absorption and decomposition units, and the fine powder recovery module at the outlet of the decomposition unit: ① The leakage flow is reduced by ≥50% compared with the no gas locking structure; ② The CO2 volume fraction in the decomposition gas is increased by about 8-15%; ③ The fine powder loss is reduced by 20-60%; This improves the system circulation stability and reduces the amount of supplementary material.

[0071] To form a clear binding of structure→mechanism→effect.

[0072] In Example 2, the A / B two-way flue gas (20% CO2, 280℃; 25% CO2, 120℃) is mixed by the system and then enters the absorption reactor, and both are successfully captured and regenerated into CO2 with a purity of ≥90% in the decomposition furnace. This proves that the system has the ability to adapt to different industrial sources of CO2 components.

[0073] 4. Heat integration significantly reduces the demand for external heat supply.

[0074] 5. Intelligent control realizes self-adaptive adjustment of CaO circulation amount.

[0075] In Example 2, the control system can automatically adjust the CaO / CaCO3 cycle times (in the range of 20-80 times) by monitoring the CO2 loading changes.

[0076] In summary, the example data sufficiently prove that the present application achieves the expected technical effects in the aspects of CO2 capture purity improvement, adsorbent cycle life, energy utilization efficiency and system intelligent control, and has significant practical value.

[0077] The above description of disclosed examples enables one of ordinary skill in the art to make or use the application. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other examples without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A carbon dioxide capture and carbon dioxide-rich preparation system based on carbonate cycle, characterized by, The application relates to a carbon dioxide capture system, which comprises a carbon dioxide-containing gas supply unit, a carbonate cycle carbon capture unit, a carbon dioxide purification unit and a heat energy integration and control unit. The carbonate cycle carbon capture unit comprises an absorption reactor, a regeneration reactor, a first solid conveying device and a second solid conveying device; the absorption reactor is filled with solid absorbents; the solid outlet of the absorption reactor is connected with the solid inlet of the regeneration reactor through the first solid conveying device; and the solid outlet of the regeneration reactor is connected with the solid inlet of the absorption reactor through the second solid conveying device. The carbon dioxide-containing gas supply unit, the absorption reactor, the regeneration reactor and the carbon dioxide purification unit are sequentially connected through pipelines along a gas flow process. The heat energy integration and control unit comprises at least one heat exchange device for recycling at least part of the heat of the regeneration reactor. The heat energy integration and control unit comprises a heat exchanger I; the flue gas outlet of the regeneration reactor is provided with the heat exchanger I; and the heat exchanger I is used for integrating and utilizing the waste heat of the regeneration reactor.

2. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, The carbon dioxide-containing gas supply unit comprises a carbon dioxide-containing gas inlet pipeline and a dust remover; the carbon dioxide-containing gas inlet pipeline is provided with a heat exchanger IV; the carbon dioxide-containing gas inlet pipeline, the dust remover and the absorption reactor are sequentially connected through pipelines; the carbon dioxide-containing flue gas or process gas in the carbon dioxide-containing gas inlet pipeline is from a combustion device, an industrial furnace, a boiler tail gas, a cement kiln tail gas, a steelmaking / blast furnace gas purification tail gas, a chemical tail gas or a waste incineration flue gas.

3. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, The absorption reactor is a fluidized bed carbon capture absorption tower, a moving bed carbon capture absorption tower, a bubbling bed carbon capture absorption tower or a rotary kiln carbon capture absorption tower.

4. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, The regeneration reactor is a rotary kiln, a fluidized bed furnace, a shaft kiln or an electric heating furnace; and the heat supply mode of the regeneration reactor is one or a combination of external fuel, electric heating, oxygen-enriched combustion and heat carrier circulation. The carbonate cycle carbon capture unit selects a calcium carbonate cycle to capture carbon dioxide; the first solid conveying device comprises a first elevator and a first conveying belt; the second solid conveying device comprises a second elevator and a second conveying belt; the solid outlet of the absorption reactor is sequentially connected with the solid inlet of the regeneration reactor through the first elevator and the first conveying belt; and the solid outlet of the regeneration reactor is sequentially connected with the solid inlet of the absorption reactor through the second elevator and the second conveying belt. The carbon dioxide purification unit comprises a precooling and dust removal device, a washing or deacidification device, a drying and adsorption device, a desulfurization device and a compression and pressure regulation device I.

5. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, The precooling and dust removal device comprises a heat exchanger V or a condenser, a cyclone separator I, a bag dust collector or an electric dust collector; The washing or deacidification device is a washing tower or a gas washing tower; The drying and adsorption device comprises a compressor I, a molecular sieve or activated alumina dryer I and an activated carbon adsorber I or an adsorption tower; The desulfurization device is a desulfurization tower or an alkali washing tower; The compression and pressure regulation device I is a compressor II or a pressure regulating valve. ​ The regeneration reactor, cyclone separator I, bag filter or electrostatic precipitator, scrubbing tower or gas scrubbing tower, compressor I, molecular sieve or activated alumina dryer I, activated carbon adsorber I or adsorption tower, desulfurization tower or alkaline scrubbing tower, and compressor II or pressure regulating valve are connected in sequence via pipelines. A heat exchanger V or condenser is provided on the pipeline connecting the regeneration reactor and cyclone separator I, bag filter or electrostatic precipitator.

6. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, The solid adsorbent includes one or a combination of several of the following: CaO, MgO, SrO, BaO, red mud activated adsorbent, or steel slag activated adsorbent.

7. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 6, characterized by, The activation treatment of the red mud activated adsorbent and / or steel slag activated adsorbent includes calcination, hydration and / or mechanical activation.

8. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, The absorption reactor is also connected to an adsorbent feeding branch and / or a deactivated solid slag discharge branch.

9. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, It also includes a system monitoring and intelligent control unit, which adopts a PLC or DCS system. The PLC or DCS control system is connected to the carbon dioxide gas supply unit, the carbonate circulation carbon capture unit, the carbon dioxide purification unit and the thermal energy integration and control unit through signal lines and / or industrial buses, respectively.

10. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 1, characterized in that, It also includes an air-locking structure, which is disposed at at least one location on the solid transport pipeline between the absorption reactor and the regeneration reactor.

11. The system for carbon dioxide capture and carbon dioxide rich preparation based on carbonate cycle according to claim 5, characterized by, It also includes a fine powder recovery pipeline and a fine powder recovery device. The fine powder recovery pipeline is connected to the pipeline connecting the regeneration reactor and the heat exchanger or condenser. The fine powder recovery pipeline, the fine powder recovery device and the regeneration reactor are connected in sequence via pipelines.

12. A method for carbon dioxide capture and carbon dioxide-rich preparation based on carbonate cycle, characterized by, Includes the following steps: 1) Using the system described in claim 1, carbon dioxide-containing flue gas or process gas is fed into an absorption reactor, so that the carbon dioxide-containing gas comes into contact with calcium oxide solid to generate carbonate solid; 2) The carbonate solid obtained in step 1) is fed into the regeneration reactor and decomposed at 750-1100℃ to generate calcium oxide solid and carbon dioxide-rich gas. 3) The carbon dioxide-rich gas obtained in step 2) is sent to a carbon dioxide purification unit for dust removal, dehydration and / or deacidification treatment to obtain carbon dioxide raw material gas; 4) Return the calcium oxide solid obtained in step 2) to the absorption reactor in step 1) for recycling.

13. The method of claim 12, wherein the carbonate cycle is based on the reaction of carbon dioxide with calcium carbonate to form calcium bicarbonate, and the calcium bicarbonate is decomposed to produce calcium carbonate and carbon dioxide. The absorption reactor operates at 300-700℃; the calcium oxide solid obtained in step 2) is returned to the absorption reactor in step 1) for recycling ≥40 times; the volume fraction of the carbon dioxide feed gas is not less than 90%.

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