Using chemical chain hydrogen production technology to achieve CO2 reduction in carbon emission sources 2 Systems and methods for capture

Abstract

The present invention relates to a system and method for capturing CO2 in a carbon emission source using chemical chain hydrogen production technology, using the heat released in the fuel chemical chain hydrogen production process to provide energy for a CO2 release unit in the CO2 capture process of a carbon emission source, and using water vapor generated by a reduction reaction to reduce the carbon dioxide partial pressure in the CO2 release unit, which is beneficial for the CO2 release unit to precipitate CO2. This method can achieve efficient conversion of fuel chemical energy while reducing the energy consumption of CO2 capture in a carbon emission source, and can reduce equipment investment costs compared to separately performing fuel chemical chain hydrogen production and capturing CO2 in flue gas.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 capture, and in particular to a system and method for capturing CO2 from carbon emission sources using chemical chain hydrogen production technology. Background Art

[0002] Human activities have caused a large increase in greenhouse gases in the atmosphere, which has led to a series of severe climate problems. It is urgent to reduce greenhouse gas emissions and mitigate the greenhouse effect. CO2 is the main gas that causes the greenhouse effect. Conventional CO2 capture includes pre-combustion, post-combustion capture, oxygen-enriched combustion and other processes. Post-combustion capture has a low concentration of CO2 in the flue gas due to the dilution of N2 in the air, resulting in high energy consumption of existing post-combustion capture. Before combustion, CO2 needs to be separated by gasification or reforming and water-gas shift. The fuel conversion process is relatively complicated. Oxygen-enriched combustion achieves the enrichment of high-concentration CO2 in the flue gas at the cost of separating pure oxygen. Expensive air separation devices and high air separation energy consumption are the main factors leading to the high capture cost of the oxygen-enriched combustion technology route. In addition, for cement and refining industries, the use of post-combustion capture requires a large amount of steam and electricity. It is necessary to build additional cogeneration systems or recover high-temperature heat through calcium cycle pure oxygen combustion to generate electricity to meet the capture energy consumption requirements, which has further increased the capture cost. It is urgent to further develop technologies that can reduce the cost of carbon capture. Summary of the invention

[0003] In view of the problem that the energy utilization efficiency of the capture process of low-concentration emission sources is low, resulting in high capture energy consumption and high capture cost, the first purpose of the present invention is to provide a system for capturing CO2 in carbon emission sources using chemical chaining hydrogen production technology, and the second purpose is to provide a method for capturing CO2 in carbon emission sources using chemical chaining hydrogen production technology. The present invention uses the heat released by the air reactor or the hydrogen production process to provide energy for the desorption process of capturing CO2 from the emission source; at the same time, the products generated by the fuel, namely CO2 and H2O, are used as the driving force for the release process, thereby reducing the equilibrium partial pressure of the regeneration process and lowering the reaction temperature of the release unit. The present invention achieves low-energy capture of fuel CO2 and emission source CO2 while efficiently producing hydrogen.

[0004] In order to achieve the above object, the specific scheme adopted by the present invention is:

[0005] First, a system for capturing CO2 from carbon emission sources using chemical chain hydrogen production technology, including a carbonization reactor, a calcination reactor, an air reactor, a fuel reactor, and a hydrogen production reactor;

[0006] The carbonization reactor is connected to the calcination reactor, the calcination reactor is also connected to the air reactor, the fuel reactor and the hydrogen production reactor respectively, the fuel reactor is also connected to the air reactor and the hydrogen production reactor respectively, and the hydrogen production reactor is also connected to the air reactor;

[0007] The carbonization reactor is used as a carbon dioxide binding unit, and uses a carbon dioxide separation aid to capture CO2 from a low-concentration emission source, and then the carbon dioxide binding carrier obtained by combining the carbon dioxide separation aid with CO2 is sent to the calcination reactor;

[0008] The calcination reactor is used as a carbon dioxide release unit, and the reaction product in the fuel reactor is used to reduce the carbon dioxide partial pressure. The carbon dioxide is combined with the carrier to decompose into a carbon dioxide separation agent and release carbon dioxide and water vapor. After condensation and separation, high-purity carbon dioxide can be obtained. The carbon dioxide separation agent is returned to the carbonization reactor to form an agent cycle;

[0009] The air reactor is used as an oxidation unit to react air with an intermediate metal oxygen carrier at a high temperature to obtain an oxidized oxygen carrier and oxygen-depleted air, while releasing heat; the oxidized oxygen carrier is sent to a fuel reactor, and the released heat is passed to a calcination reactor to provide heat for a carbon dioxide release unit;

[0010] The fuel reactor is used as a reduction unit to react the oxidized oxygen carrier with the fuel at high temperature to obtain the reduced oxygen carrier and generate CO2 and water vapor. After gas-solid separation, the reduced oxygen carrier is sent to the hydrogen production reactor, and the CO2 and water vapor are passed into the calcination reactor;

[0011] The hydrogen production reactor is used as a hydrogen production unit, water vapor is introduced, and the reduced oxygen carrier is reacted with the water vapor to obtain an intermediate oxygen carrier, generate hydrogen, and release heat; the intermediate oxygen carrier is sent to the air reactor to form an oxygen carrier cycle, and the released heat is passed into the calcination reactor to provide heat for the carbon dioxide release unit;

[0012] In the above auxiliary agent cycle, CaO / CaCO3 is used to desorb carbon dioxide;

[0013] In the above oxygen carrier cycle, Fe2O3-Fe3O4-FeO is used as the oxygen carrier;

[0014] In the above system, the heat released in the air reactor and / or the hydrogen production reactor provides energy for the desorption process of the CO2 capture emission source; at the same time, the reaction products CO2 and H2O generated by the fuel in the fuel reactor are used as the driving force of the release process.

[0015] In the second aspect, a method for capturing CO2 from carbon emission sources using chemical chain hydrogen production technology is provided, wherein the method simultaneously realizes efficient fuel conversion to produce hydrogen, and low-energy CO2 capture of fuel carbon components and flue gas carbon emission sources, and comprises the following steps:

[0016] (1) introducing flue gas into a carbon dioxide combining unit containing a carbon dioxide separation agent, wherein the carbon dioxide separation agent captures carbon dioxide in the flue gas, and then obtains decarbonized flue gas and a carbon dioxide combining carrier after gas-solid or gas-liquid separation; the carbon dioxide combining carrier refers to a product obtained by combining the carbon dioxide separation agent with carbon dioxide;

[0017] (2) The carbon dioxide-binding carrier obtained in step (1) is fed into a carbon dioxide release unit, and the CO2 partial pressure is reduced by introducing the product of the reduction unit by changing the reaction conditions, so that the carbon dioxide-binding carrier is decomposed into a carbon dioxide separation agent and carbon dioxide is released, thereby obtaining carbon dioxide and water vapor, which are separated after condensation to obtain high-purity carbon dioxide, and the carbon dioxide separation agent is returned to step (1) to form an agent cycle;

[0018] (3) passing air and the intermediate metal oxygen carrier into an oxidation unit to obtain an oxidized oxygen carrier and oxygen-depleted air under high temperature reaction conditions, while releasing heat; the released heat provides energy for the carbon dioxide release unit in step (2);

[0019] (4) The oxidized metal oxygen carrier obtained in step (3) is fed into a reduction unit together with a fuel. Under high temperature reaction conditions, the oxidized metal oxygen carrier reacts with the fuel to obtain a reduced metal oxygen carrier and generate CO2 and water. After gas-solid separation, the reduced gas product is fed into the carbon dioxide release unit of step (2) to reduce the carbon dioxide partial pressure;

[0020] (5) The reduced metal oxygen carrier obtained in step (4) and water vapor are fed into a hydrogen production unit, where the reduced oxygen carrier is oxidized into an intermediate metal oxygen carrier and hydrogen is generated simultaneously. After gas-solid separation, the gas product is condensed to obtain high-purity hydrogen. The intermediate metal oxygen carrier is fed into the oxidation unit of step (3) to form an oxygen carrier cycle. The heat released by the hydrogen production unit is used to generate electricity or provide energy for the carbon dioxide release unit.

[0021] (6) The carbon dioxide combining unit, hydrogen production unit and oxidation unit are all exothermic processes, while the carbon dioxide releasing unit and reduction unit are endothermic processes; the heat required for the reduction unit is provided by the heat carried by the oxygen carrier of the oxidation unit, and the heat required for the carbon dioxide releasing unit is provided by the heat of the oxidation unit or the hydrogen production unit according to the release temperature.

[0022] Preferably, in step (1), the flue gas introduced into the carbon dioxide combining unit includes flue gas from power plants, cement, chemical, steel and other process gases containing CO2.

[0023] Preferably, in step (1), the carbon dioxide separation aid is an absorbent or adsorbent such as CaO or MgO.

[0024] Preferably, in step (4), the fuel fed into the reduction unit includes coal, natural gas, synthesis gas, biomass, coke oven gas and other gas, liquid or solid with calorific value; further, the ratio of the oxidized metal oxygen carrier to the fuel ensures that the reduction unit fuel is completely converted into CO2 and H2O. The products CO2 and H2O of the reduction unit enter the CO2 release unit to reduce the equilibrium partial pressure of CO2 release.

[0025] Preferably, the oxygen carrier is a metal oxygen carrier. Further, the oxygen carrier includes Fe, FeO, Co, Ni or Cu.

[0026] Preferably, the reaction temperature of the carbon dioxide combining unit is 40-800°C.

[0027] Preferably, the reaction temperature of the carbon dioxide release unit is 800-950°C.

[0028] Preferably, the reaction temperature of the oxidation unit is 800-1200°C.

[0029] Preferably, the reaction temperature of the reduction unit is 600-1000°C.

[0030] Preferably, the reaction temperature of the hydrogen production unit is 500-900°C.

[0031] Preferably, the heat released by the oxidation unit and the hydrogen production unit is provided to the CO2 release unit according to the temperature matching of the CO2 release unit.

[0032] The beneficial effects of the present invention are:

[0033] The present invention utilizes the heat released by the oxidation reaction unit or the hydrogen production reaction unit in the fuel chemical chain hydrogen production process to provide energy for the reduction reaction unit and the carbon dioxide release unit, thereby realizing self-heating of the process; at the same time, the water vapor generated by the reduction reaction is utilized to reduce the carbon dioxide partial pressure, which is beneficial to driving the precipitation of carbon dioxide in the carbon dioxide release unit; the present invention realizes the energy matching between the fuel hydrogen production unit and the carbon emission source CO2 capture unit by adjusting the circulating carrier ratio. While realizing efficient fuel hydrogen production, the present invention can realize zero-energy capture of carbon dioxide in the fuel conversion process and reduce the energy consumption of carbon dioxide capture from the emission source, thereby reducing equipment investment compared to separately carrying out fuel chemical chain hydrogen production and capturing CO2 in flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1This is a schematic diagram of the principle of the method for capturing CO2 in flue gas from carbon emission sources by coupling fuel chemical chain to produce hydrogen as described in the present invention.

[0035] Figure 2 This is a schematic diagram of a typical process flow of the method for capturing CO2 in flue gas from carbon emission sources by coupling fuel chemical chain to produce hydrogen according to the present invention.

[0036] Figure 3 The typical process flow chart of the reference object selected for the present invention is a simple combination of a fuel hydrogen production process and a carbon emission source flue gas CO2 capture process.

[0037] Figure 4 The typical process flow of the reference object selected for the present invention is the calcium cycle combustion and then capture process. DETAILED DESCRIPTION

[0038] The capture of CO2 from carbon emission sources faces the problems of high cost and high energy consumption, especially the capture of carbon dioxide from low-concentration carbon emission sources requires a large amount of energy. For low-concentration emission sources in cement, refining and other factories, it is necessary to build a new cogeneration power plant to provide steam and electricity or to recover high-temperature heat through calcium cycle pure oxygen combustion to generate electricity to meet the energy demand of the capture process, resulting in high CO2 capture costs. The present invention eliminates the air separation unit that originally provided the energy process in the calcium cycle pure oxygen combustion process, and realizes the low-energy capture of fuel CO2 and low-concentration emission source CO2 while efficiently producing hydrogen.

[0039] Fossil fuels achieve low-carbon hydrogen production through chemical chain hydrogen production, while providing the energy required to capture CO2 emissions.

[0040] Specific work unit refinement:

[0041] In the original three-reactor chemical chain hydrogen production process, the three reactors are all adiabatic; in the present invention, by adjusting the carrier ratio and reaction conditions of the reactor, energy is provided for the release process in the post-combustion capture unit;

[0042] The original post-combustion technology only desorbs CO2 through a heat-driven release process; the present invention utilizes the product of the chemical chain hydrogen production process to drive the release process, which can reduce the release temperature of the release process and provide part of the energy at the same time.

[0043] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the accompanying drawings.

[0044] Example 1

[0045] like Figure 1 As shown, the method of the present invention involves a chemical chain hydrogen production cycle and a CO2 auxiliary agent separation cycle.

[0046] In the CO2 agent separation cycle, the flue gas from the emission source enters the carbon dioxide combination unit after passing through the desulfurization and denitrification purification units, wherein the carbon dioxide separation agent can react with the carbon dioxide in the flue gas from the emission source to absorb the carbon dioxide in the flue gas. The reaction temperature of the carbon dioxide combination unit is between 40-800°C, and the pressure is normal pressure or high pressure. After the carbon dioxide separation agent captures carbon dioxide, a carbon dioxide combination carrier is obtained. The decarbonized flue gas passes through a gas-solid separator to separate the decarbonized flue gas from the solid, thereby achieving carbon dioxide capture in the flue gas from the emission source. The carbon dioxide combination carrier separated from the decarbonized flue gas enters the carbon dioxide release unit, which is provided with energy by the heat released by the oxidation unit or the hydrogen production unit. At the same time, the carbon dioxide combination carrier is decomposed into carbon dioxide separation agent and carbon dioxide under the drive of the reduction product of the reduction unit. Depending on the selected carrier, the reaction temperature of the carbon dioxide release unit is between 800-950°C. The carbon dioxide separation agent is circulated back to the carbon dioxide combination unit after gas-solid separation, and the obtained gas product can be separated after condensation to obtain high-purity carbon dioxide.

[0047] The chemical chain hydrogen production cycle includes an oxidation unit, a reduction unit and a hydrogen production unit. In the oxidation unit, air reacts with an intermediate oxygen carrier to release heat, the reaction temperature is 800-1200°C, and the reaction pressure is normal pressure or high pressure. The heat released in this process can provide a carbon dioxide release unit or generate high-temperature steam after heat recovery and generate electricity through a thermodynamic cycle. Air reacts with an intermediate oxygen carrier to obtain oxygen-depleted air and an oxidized oxygen carrier. After gas-solid separation, the oxidized oxygen carrier is sent to the reduction unit to react with the fuel. The reaction temperature is 600-1000°C and the reaction pressure is normal pressure or high pressure. In the reduction unit, the oxidized oxygen carrier is reduced to a reduced state by the fuel and generates carbon dioxide and H2O at the same time. After gas-solid separation, the gas reduction product is sent to the CO2 release unit to drive CO2 release, and the solid reduced oxygen carrier is sent to the hydrogen production unit to react with water vapor to produce hydrogen. In the hydrogen production unit, the reduced oxygen carrier is oxidized by water vapor to generate hydrogen. The reaction temperature of the hydrogen production unit is 500-900°C and the pressure is normal pressure or high pressure. The obtained product is separated from the gas by a gas-solid separator and then condensed to obtain a hydrogen product. The separated reduced metal oxygen carrier is sent to an oxidation unit to form an oxygen carrier cycle.

[0048] Figure 2 The figure is a typical process flow diagram of the present invention for realizing CO2 capture from carbon emission sources by utilizing chemical chain hydrogen production technology. Figure 2As shown, in this typical implementation case, CaO / CaCO3 and Fe2O3-Fe3O4-FeO are selected as CO2 separation carriers and oxygen carriers for chemical chain hydrogen production, respectively, and natural gas is used as a typical fuel. First, the flue gas reacts with the CaO carrier in the carbonization unit, and part of the CaO reacts with the CO2 in the flue gas to generate CaCO3. After gas-solid separation, the solid containing CaCO3 is sent to the calcination reactor. Driven by the high temperature and the gas product of the fuel reactor, CaCO3 is decomposed into CO2 and CaO. After gas-solid separation, CaO is sent back to the carbonization unit to reabsorb the CO2 in the flue gas, and the gas product (mainly CO2 and water) is further condensed after heat recovery to obtain high-purity CO2. Since the calcination reactor and the carbonization reaction temperature are high and the carbonization reaction releases heat, the sensible heat carried by the decarbonized flue gas and the calcination reaction gas product and the heat released by the carbonization reaction are recovered through the waste heat boiler to generate high-temperature steam to drive the steam turbine to do work. Since the calcination reaction is endothermic, the required heat is provided by the oxidation process of the air reactor. In the air reactor, the intermediate oxygen carrier Fe3O4 is oxidized by the preheated air to the oxidized oxygen carrier Fe2O3. After gas-solid separation, the oxygen-depleted air is preheated by heat recovery. After heat recovery, the oxygen-depleted air is directly discharged into the atmosphere or further thermally utilized, while the oxidized oxygen carrier Fe2O3 is sent to the fuel reactor to react with natural gas. In the fuel reactor, the natural gas reduces the oxidized oxygen carrier Fe2O3 to the reduced oxygen carrier FeO, and generates gas products whose main components are CO2 and H2O. After gas-solid separation, the gas products are sent to the calcination reactor to drive the decomposition of CaCO3, while the reduced oxygen carrier FeO is sent to the hydrogen production reactor to react with water vapor. In the hydrogen production reactor, water vapor oxidizes the reduced oxygen carrier FeO into the intermediate oxygen carrier Fe3O4 and generates hydrogen. After gas-solid separation, the gas products (mainly water vapor and hydrogen) are heat recovered by preheating the reactants, and high-purity hydrogen can be obtained after further condensation. The intermediate oxygen carrier Fe3O4 is sent to the air reactor for oxidation reaction to complete the oxygen carrier cycle.

[0049] In this typical case, the relevant reaction conditions are selected as follows: the temperature of the carbonization reactor is 650°C, the molar ratio of CaO to CO2 in the carbonization reactor is 4.25, the CaO conversion is 20%, the temperature of the calcination reactor is 900°C, the temperature of the air reactor is 950°C, the fuel reactor and the hydrogen production reactor are both insulated, the waste heat boiler adopts three-pressure reheating technology, which are 126bar / 566°C, 26bar / 566°C, and 5.5bar / 305°C respectively, the exhaust temperature of the waste heat boiler is 125°C, and the pressure is slightly positive.

[0050] In order to further illustrate the beneficial effects of the present invention, comparative example 1 is further selected as a reference object. The process flow chart of comparative example 1 is as follows Figure 3 shown.

[0051] Figure 3 This is a typical process flow chart of the comparative embodiment selected by the present invention. In this process, CO2 capture in flue gas and fuel chemical chain hydrogen production are carried out in parallel. Figure 3 As shown, after the natural gas is split, it enters the fuel chemical chain hydrogen production unit and the chemical chain combustion coupled calcium cycle CO2 capture unit respectively. In the fuel chemical chain hydrogen production unit, in the air reactor, the intermediate oxygen carrier Fe3O4 is oxidized by the preheated air to the oxidized oxygen carrier Fe2O3. After gas-solid separation, the oxygen-depleted air is preheated by heat recovery. After heat recovery, the oxygen-depleted air is directly discharged into the atmosphere or further thermally utilized, while the oxidized oxygen carrier Fe2O3 is sent to the fuel reactor to react with natural gas. In the fuel reactor, the natural gas reduces the oxidized oxygen carrier Fe2O3 to the reduced oxygen carrier FeO, and generates gas products whose main components are CO2 and H2O. After gas-solid separation, the gas products are sent to the waste heat boiler to recover heat and generate electricity, while the reduced oxygen carrier FeO is sent to the hydrogen production reactor to react with water vapor. In the hydrogen production reactor, water vapor oxidizes the reduced oxygen carrier FeO into the intermediate oxygen carrier Fe3O4 and generates hydrogen. After gas-solid separation, the gas products (mainly water vapor and hydrogen) are heat recovered by preheating the reactants, and high-purity hydrogen can be obtained after further condensation. The intermediate oxygen carrier Fe3O4 is sent to the air reactor for oxidation reaction to complete the oxygen carrier cycle.

[0052] In the chemical chain combustion coupled with calcium cycle to capture CO2, the flue gas reacts with the CaO carrier in the carbonization unit, and part of the CaO reacts with the CO2 in the flue gas to form CaCO3. After gas-solid separation, the solid containing CaCO3 is sent to the calcination reactor. Driven by the high temperature and the gas products of the fuel reactor in the chemical chain combustion process, CaCO3 is decomposed into CO2 and CaO. After gas-solid separation, CaO is sent back to the carbonization unit to reabsorb the CO2 in the flue gas, and the gas products (mainly CO2 and water) are further condensed after heat recovery to obtain high-purity CO2. Since the calcination reaction is endothermic, the required heat is provided by the chemical chain combustion process. In the chemical chain combustion process, Fe3O4 / Fe2O3 is used as an oxygen carrier. In the air reactor, Fe3O4 reacts with air to generate Fe2O3. The heat released in the process is provided to the calcination reactor. After gas-solid separation, Fe2O3 is sent to the fuel reactor to react with natural gas to generate gas products with CO2 and H2O as the main components. After gas-solid separation, the gas products are sent to the calcination unit to drive the decomposition of CaCO3, and the solid oxygen carrier Fe3O4 is sent to the air reactor to complete the chemical chain combustion cycle. In addition, a waste heat boiler is used to recover the sensible heat of the flue gas in each process and the reaction heat of the carbonization process.

[0053] In Control Example 1, the relevant reaction conditions are selected as follows: In the chemical chain combustion coupled calcium cycle CO2 capture unit, the temperature of the carbonization reactor is 650°C, the molar ratio of CaO to CO2 in the carbonization reactor is 4.25, the CaO conversion is 20%, the temperature of the calcination reactor is 900°C, the temperature of the air reactor is 950°C, and the fuel reactor is adiabatic. In the fuel chemical chain hydrogen production reactor, the air reactor temperature, the fuel reactor and the hydrogen production reactor are all adiabatic. The waste heat boiler adopts three-pressure reheating technology, which are 126bar / 566°C, 26bar / 566°C, and 5.5bar / 305°C respectively. The exhaust temperature of the waste heat boiler is 125°C and the pressure is slightly positive.

[0054] The natural gas and flue gas components based on the typical embodiment and comparative example 1 are shown in Tables 1 and 2, and the performance comparison is shown in Table 3. Compared with the comparative example, the energy efficiency of the typical embodiment is 7.1 percentage points higher than that of comparative example 1 under the same natural gas, flue gas input and the same CO2 capture amount, and has a good energy utilization effect.

[0055] Table 1 Input natural gas composition

[0056] project unit Numeric temperature ℃ 15 pressure bar 1.013 Molar flow kmol / h 2067.7 Low calorific value MJ / kg 45.3 Composition (volume fraction) <![CDATA[CH4]]> ％ 79.75 <![CDATA[C2H6]]> ％ 9.68 <![CDATA[C3H8]]> ％ 4.45 <![CDATA[C4H 10 ]]> ％ 2.37 <![CDATA[CO2]]> ％ 2.92 <![CDATA[N2]]> ％ 0.83

[0057] Table 2 Input flue gas composition

[0058]

[0059]

[0060] Table 3 Performance comparison

[0061] project Example Comparative Example 1 enter Natural gas (MW) 535.5 535.5 Flue gas (kmol / h) 14716.1 14716.1 Output Hydrogen (MW) 332.6 270.1 Electricity (MW) 54.8 79.2 Energy efficiency (%)* 72.3 65.2 <![CDATA[CO2 capture amount (kg / s)]]> 58.8 58.8

[0062] *Energy efficiency = (hydrogen output + electricity output) / (natural gas input)

[0063] The present invention discloses a method for capturing CO2 from a carbon emission source using chemical chain hydrogen production technology. The present invention utilizes the heat released during the fuel chemical chain hydrogen production process (heat released by the oxidation unit or heat released by the hydrogen production unit) to provide energy for a CO2 release unit in the process of capturing CO2 from a carbon emission source. At the same time, water vapor generated by the reduction reaction is used to reduce the carbon dioxide partial pressure in the CO2 release unit, which is beneficial to the precipitation of CO2 from the CO2 release unit, thereby increasing the efficiency of the system by 5-8 percentage points.

[0064] Comparative Example 2: Conventional post-combustion technology, with calcium cycle pure oxygen combustion heating as the reference object, the calcium cycle post-combustion capture flow chart is as follows Figure 4As shown. In this comparative example, the relevant reaction conditions are selected as follows: the temperature of the carbonization reactor is 650°C, the molar ratio of CaO to CO2 in the carbonization reactor is 4.25, the CaO conversion is 20%, the temperature of the calcination reactor is 900°C, the fuel is natural gas, the oxygen purity of the air separation unit is 95%, the power consumption of the air separation unit is 180kWh / tO2, the waste heat boiler adopts three-pressure reheating technology, which are 126bar / 566°C, 26bar / 566°C, 5.5bar / 305°C, respectively, the exhaust temperature of the waste heat boiler is 125°C, and the pressure is slightly positive. The results are shown in Table 4 below.

[0065] Table 4 Results comparison

[0066]

[0067]

[0068] It should be noted that the above-described embodiments should be understood as illustrative rather than limiting the scope of protection of the present invention, and the scope of protection of the present invention shall be subject to the claims. For those skilled in the art, some non-essential improvements and adjustments made to the present invention still fall within the scope of protection of the present invention without departing from the essence and scope of the present invention.

Claims

1. A system for capturing CO2 from carbon emission sources using chemical chain hydrogen production technology, characterized by: It includes a carbonization reactor, a calcination reactor, an air reactor, a fuel reactor and a hydrogen production reactor; The carbonization reactor is connected to the calcination reactor, the calcination reactor is also connected to the air reactor, the fuel reactor and the hydrogen production reactor respectively, the fuel reactor is also connected to the air reactor and the hydrogen production reactor respectively, and the hydrogen production reactor is also connected to the air reactor; The carbonization reactor is used as a carbon dioxide binding unit, and uses a carbon dioxide separation aid to capture CO2 from a low-concentration emission source, and then the carbon dioxide binding carrier obtained by combining the carbon dioxide separation aid with CO2 is sent to the calcination reactor; The calcination reactor is used as a carbon dioxide release unit, and the reaction product in the fuel reactor is used to reduce the carbon dioxide partial pressure. The carbon dioxide is combined with the carrier to decompose into a carbon dioxide separation agent and release carbon dioxide and water vapor. After condensation and separation, high-purity carbon dioxide can be obtained. The carbon dioxide separation agent is returned to the carbonization reactor to form an agent cycle; The air reactor is used as an oxidation unit to react air with an intermediate metal oxygen carrier at a high temperature to obtain an oxidized oxygen carrier and oxygen-depleted air, while releasing heat; the oxidized oxygen carrier is sent to a fuel reactor, and the released heat is passed to a calcination reactor to provide heat for a carbon dioxide release unit; The fuel reactor is used as a reduction unit to react the oxidized oxygen carrier with the fuel at high temperature to obtain the reduced oxygen carrier and generate CO2 and water vapor. After gas-solid separation, the reduced oxygen carrier is sent to the hydrogen production reactor, and the CO2 and water vapor are passed into the calcination reactor; The hydrogen production reactor is used as a hydrogen production unit, water vapor is introduced, and the reduced oxygen carrier is reacted with the water vapor to obtain an intermediate oxygen carrier, generate hydrogen, and release heat; the intermediate oxygen carrier is sent to the air reactor to form an oxygen carrier cycle, and the released heat is passed into the calcination reactor to provide heat for the carbon dioxide release unit; In the above system, the heat released in the air reactor and / or the hydrogen production reactor provides energy for the desorption process of the CO2 capture emission source; at the same time, the reaction products CO2 and H2O generated by the fuel in the fuel reactor are used as the driving force of the release process.

2. The system according to claim 1, characterized in that: In the auxiliary agent cycle, CaO / CaCO3 is used to desorb carbon dioxide; in the oxygen carrier cycle, Fe2O3-Fe3O4-FeO is used as the oxygen carrier.

3. A method for capturing CO2 from carbon emission sources using chemical chain hydrogen production technology, characterized in that: The method is applied to the system of claim 1, and simultaneously realizes efficient fuel conversion to produce hydrogen, and low-energy CO2 capture of fuel carbon components and post-combustion flue gas carbon emission sources, and comprises the following steps: (1) introducing flue gas into a carbon dioxide combining unit containing a carbon dioxide separation agent, wherein the carbon dioxide separation agent captures carbon dioxide in the flue gas, and then obtains decarbonized flue gas and a carbon dioxide combining carrier after gas-solid or gas-liquid separation; the carbon dioxide combining carrier refers to a product obtained by combining the carbon dioxide separation agent with carbon dioxide; (2) The carbon dioxide-binding carrier obtained in step (1) is fed into a carbon dioxide release unit, and the CO2 partial pressure is reduced by introducing the product of the reduction unit by changing the reaction conditions, so that the carbon dioxide-binding carrier is decomposed into a carbon dioxide separation agent and carbon dioxide is released, thereby obtaining carbon dioxide and water vapor, which are separated after condensation to obtain high-purity carbon dioxide, and the carbon dioxide separation agent is returned to step (1) to form an agent cycle; (3) passing air and the intermediate metal oxygen carrier into an oxidation unit to obtain an oxidized oxygen carrier and oxygen-depleted air under high temperature reaction conditions, while releasing heat; the released heat provides energy for the carbon dioxide release unit in step (2); (4) The oxidized metal oxygen carrier obtained in step (3) is fed into a reduction unit together with a fuel. Under high temperature reaction conditions, the oxidized metal oxygen carrier reacts with the fuel to obtain a reduced metal oxygen carrier and generate CO2 and water. After gas-solid separation, the reduced gas product is fed into the carbon dioxide release unit of step (2) to reduce the carbon dioxide partial pressure; (5) The reduced metal oxygen carrier obtained in step (4) and water vapor are fed into a hydrogen production unit, where the reduced oxygen carrier is oxidized into an intermediate metal oxygen carrier and hydrogen is generated simultaneously. After gas-solid separation, the gas product is condensed to obtain high-purity hydrogen. The intermediate metal oxygen carrier is fed into the oxidation unit of step (3) to form an oxygen carrier cycle. The heat released by the hydrogen production unit is used to generate electricity or provide energy for the carbon dioxide release unit. (6) The carbon dioxide combining unit, hydrogen production unit and oxidation unit are all exothermic processes, while the carbon dioxide releasing unit and reduction unit are endothermic processes; the heat required for the reduction unit is provided by the heat carried by the oxygen carrier of the oxidation unit, and the heat required for the carbon dioxide releasing unit is provided by the heat of the oxidation unit or the hydrogen production unit according to the release temperature.

4. The method according to claim 3, characterized in that: In step (1), the flue gas introduced into the carbon dioxide combining unit is flue gas from a power plant, or a gas containing CO2 generated during cement, chemical or steel processing.

5. The method according to claim 3, characterized in that: In step (4), the fuel fed into the reduction unit is a gas, liquid or solid with calorific value.

6. The method according to claim 5, characterized in that: The fuel is coal, natural gas, synthesis gas, biomass or coke oven gas.

7. The method according to claim 3, characterized in that: In step (4), the ratio of the oxidized metal oxygen carrier to the fuel ensures that the reduction unit fuel is completely converted into CO2 and H2O.

8. The method according to claim 3, characterized in that: The reaction temperature of the carbon dioxide combining unit is 40-800°C; the reaction temperature of the carbon dioxide releasing unit is 800-950°C.

9. The method according to claim 3, characterized in that: The reaction temperature of the oxidation unit is 800-1200°C; the reaction temperature of the reduction unit is 600-1000°C; and the reaction temperature of the hydrogen production unit is 500-900°C.

10. The method according to claim 3, characterized in that: The heat released by the oxidation unit and the hydrogen production unit is provided to the carbon dioxide releasing unit according to the temperature matching of the carbon dioxide releasing unit.

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