Carbon dioxide trapping system and method based on calcium circulation and calcium-based chemical looping combustion

Abstract

The invention relates to the technical field of carbon capture after combustion, and discloses a carbon dioxide capture system and method based on calcium circulation and calcium-based chemical looping combustion. CaS, CaO and CaSO4 in the calcination reactor enter a carbon capture reactor, the fuel reacts with CaSO4 to generate CO2 and CaS, and CO2 in the flue gas reacts with CaO to generate CaCO3; caS and CaCO3 in the carbon capture reactor and a solid material flow which carries heat and contains CaSO4 and CaO in the air reactor respectively enter a calcination reactor, and CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid material flow; caS, CaSO4 and CaO in the calcination reactor are divided into two streams and enter the carbon capture reactor and the air reactor respectively, CaS and air react in the air reactor to generate CaSO4, and heat is released. According to the system, doping and dilution of CO2 product gas are avoided, and high-grade electric energy is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of post-combustion carbon capture, and in particular to a carbon dioxide capture system and method based on calcium circulation and calcium-based chemical chaining combustion. Background Art

[0002] Post-combustion carbon capture technology is currently the most widely used and mature carbon capture technology, and is an important way to achieve large-scale CO2 capture at this stage. Conventional post-combustion carbon capture devices mainly use chemical absorption technology. In the absorption tower, the CO2 in the gas to be treated (depending on the industrial process, mainly different proportions of nitrogen and carbon dioxide and a small amount of other impurity gases, hereinafter referred to as flue gas) is absorbed by the alkaline solution to achieve CO2 capture. The absorbent solution after the reaction is circulated to the regeneration tower, and reverse decomposition occurs under certain conditions to release CO2, thereby achieving the regeneration of the absorbent. The CO2 released from the regeneration tower is then compressed, liquefied, and sent to the downstream utilization and storage links. The chemical absorption carbon capture process has good selectivity, high CO2 absorption rate, and the desorbed CO2 gas has high purity. However, the heating and regeneration of the commonly used composite amine absorbents consumes a lot of electricity or steam, resulting in high system energy consumption, which seriously affects the large-scale promotion and application of this technology. The composite amine absorbents also have problems such as degradation leading to decreased absorption / desorption performance and environmental pollution caused by amine escape during long-term circulation operation. The heating and heat exchange of large amounts of solution make the equipment large and complex.

[0003] The calcium cycle based on CaO / CaCO3 is an effective way to capture CO2 in flue gas. The process utilizes the carbonation reaction of calcium oxide (CaO+CO2=CaCO3) and the calcination decomposition reaction of calcium carbonate (CaCO3=CaO+CO2) for cyclic adsorption and desorption to achieve the capture and separation of CO2 in flue gas.

[0004] The calcium cycle carbon capture process is simple, the calcium-based absorbent has a large carbon absorption capacity, and has many advantages such as abundant source mineral reserves, wide distribution, and low price. However, in order to provide heat for CaO regeneration, the current calcination reactor needs to use electric heating or introduce air / oxygen and fuel combustion, resulting in a huge waste of high-grade energy and the export CO2 is doped and diluted.

[0005] The invention patent application with application number 200910304734.8 and titled "Heating and Carbon Dioxide Capture System and Method" describes a heating and carbon dioxide capture system, which uses chemical chain combustion technology to regenerate heat for CO2 absorbent. However, the system uses a chemical absorption carbon capture process, and the amine absorbent used inevitably has deficiencies such as amine liquid degradation and amine escape; the system uses copper oxide and nickel oxide as oxygen carriers. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of the existing flue gas carbon capture technology, such as the easy degradation of chemical absorbents, amine escape and high cost, as well as the high-grade energy consumption and CO2 dilution in the calcium cycle decarbonization process, and provide a carbon dioxide capture system and method based on calcium cycle and calcium-based chemical chaining combustion. The system combines the calcium cycle carbon capture technology with the calcium-based chemical chaining combustion technology, realizes carbon capture of flue gas by calcium cycle (CaO / CaCO3), realizes heat supply for the calcium cycle carbon capture process by calcium-based chemical chaining combustion (CaS / CaSO4), avoids the doping and dilution of CO2 product gas, saves high-grade electric energy, and the recycled calcium-based materials are widely available and low-priced, further saving the cost of flue gas carbon capture.

[0007] In order to achieve the above-mentioned object, the present invention provides, on one hand, a carbon dioxide capture system based on calcium circulation and calcium-based chemical chaining combustion, the system comprising a carbon capture reactor, a calcination reactor and an air reactor;

[0008] CaS, CaO and CaSO4 from the calcination reactor enter the carbon capture reactor, fuel enters the carbon capture reactor and reacts with CaSO4 to generate CO2 and CaS, CO2 generated by the reaction of fuel and CaSO4 and CO2 from flue gas react with CaO in the carbon capture reactor to generate CaCO3;

[0009] CaS and CaCO3 from the carbon capture reactor enter the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO from the air reactor enters the calcination reactor, and CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0010] The CaS, CaSO4 and CaO from the calcination reactor are divided into two streams, one of which enters the carbon capture reactor and the other enters the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO enters the calcination reactor from the air reactor.

[0011] Preferably, the type of the carbon capture reactor is selected from a fixed bed reactor, a moving bed reactor, a spouted bed reactor, a fluidized bed reactor or a transport bed reactor.

[0012] Preferably, the fuel entering the carbon capture reactor may be a gaseous fuel and / or a solid fuel.

[0013] Preferably, the fuel is selected from at least one of coal tar, coal, natural gas, synthesis gas and coke oven gas.

[0014] Preferably, when the fuel entering the carbon capture reactor is coal char, the coal char and water vapor enter the carbon capture reactor simultaneously.

[0015] Preferably, the calcination reactor is provided with a solid material supplement inlet for supplementing at least one solid material selected from the group consisting of CaSO4, CaS, CaCO3 and CaO into the calcination reactor.

[0016] Preferably, the calcination reactor is provided with a gas outlet for discharging carbon dioxide generated by the decomposition of CaCO3.

[0017] A second aspect of the present invention provides a method for capturing carbon dioxide based on calcium circulation and calcium-based chemical chaining combustion, which is implemented in the system described above and comprises the following steps:

[0018] The CaS, CaO and CaSO4 in the calcination reactor are input into the carbon capture reactor, the fuel is input into the carbon capture reactor to react with CaSO4 to generate CO2 and CaS, and the CO2 generated by the reaction of the fuel with CaSO4 and the CO2 in the flue gas react with CaO in the carbon capture reactor to generate CaCO3;

[0019] The CaS and CaCO3 in the carbon capture reactor are input into the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO in the air reactor is input into the calcination reactor, and the CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0020] The CaS, CaSO4 and CaO in the calcination reactor are divided into two streams, one of which is input into the carbon capture reactor and the other is input into the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO is input from the air reactor into the calcination reactor.

[0021] Preferably, the amounts of CaSO 4 and fuel input into the carbon capture reactor satisfy: the ratio of the number of moles of CaSO 4 to the number of moles of carbon in the fuel is greater than 1:2.

[0022] Preferably, the amounts of CaO, fuel and flue gas input into the carbon capture reactor satisfy: the ratio of the number of moles of CaO to the total number of moles of carbon in the fuel and the carbon in the flue gas is greater than 1.

[0023] Preferably, the amounts of air and CaS input into the air reactor satisfy: the ratio of the number of moles of oxygen in the air to the number of moles of CaS>2.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The CO2 capture system based on calcium cycle and calcium-based chemical looping combustion proposed in the present invention realizes carbon capture of flue gas through calcium cycle (CaO / CaCO3), avoiding the shortcomings of amine liquid degradation and amine escape existing in the traditional flue gas carbon capture scheme using amine absorbents; heat is realized for the calcium cycle carbon capture process through calcium-based chemical looping combustion (CaS / CaSO4), naturally avoiding the doping and dilution of CO2 product gas, and saving high-grade electricity; the recycled calcium-based material is widely available and low-priced, further saving the cost of flue gas carbon capture. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the carbon dioxide capture system based on calcium cycle and calcium-based chemical chaining combustion according to the present invention.

[0027] Figure 2 It is a schematic diagram of another embodiment of the present invention. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0029] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0030] The carbon dioxide capture system based on calcium cycle and calcium-based chemical chaining combustion provided by the present invention is as follows: Figure 1 As shown, it includes a carbon capture reactor, a calcination reactor and an air reactor;

[0031] CaS, CaO and CaSO4 from the calcination reactor enter the carbon capture reactor, fuel enters the carbon capture reactor and reacts with CaSO4 to generate CO2 and CaS, CO2 generated by the reaction of fuel and CaSO4 and CO2 from flue gas react with CaO in the carbon capture reactor to generate CaCO3;

[0032] CaS and CaCO3 from the carbon capture reactor enter the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO from the air reactor enters the calcination reactor, and CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0033] The CaS, CaSO4 and CaO from the calcination reactor are divided into two streams, one of which enters the carbon capture reactor and the other enters the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO enters the calcination reactor from the air reactor.

[0034] In the system described in the present invention, the carbon capture reactor mainly undergoes two reactions. The first reaction is: the fuel introduced from the outside reacts with the oxygen carrier CaSO4 from the calcination reactor to generate CO2 and CaS. During the reaction, the fuel can first undergo a gasification reaction with CO2, and the resulting product CO then reacts with the oxygen carrier CaSO4 to generate CaS and CO2. The fuel can also directly react with the oxygen carrier CaSO4 to generate CaS and CO2. The second reaction is that the CaO from the calcination reactor reacts with CO2 to generate CaCO3, wherein a portion of the CO2 comes from the CO2 in the flue gas, and a portion comes from the CO2 generated by the reaction of the fuel and the oxygen carrier CaSO4. After the reaction in the carbon capture reactor, a solid mixture mainly containing CaS and CaCO3 is obtained, and the solid mixture is input into the calcination reactor. In one embodiment, the flue gas after decarbonization is discharged from the top of the carbon capture reactor in the form of the first tail gas.

[0035] In the present invention, the carbon capture reactor may be in various forms commonly used in the art. In some preferred embodiments, in order to strengthen the gas-solid reaction, the carbon capture reactor includes, but is not limited to, a fixed bed reactor, a moving bed reactor, a spouted bed reactor, a fluidized bed reactor or a transport bed reactor.

[0036] In some embodiments, the fuel entering the carbon capture reactor may be a gaseous fuel and / or a solid fuel. In some preferred embodiments, the fuel is selected from at least one of coal char (coke), coal, natural gas, synthesis gas and coke oven gas. In order to enhance the reaction of the oxygen carrier CaSO4, when coal char is used as fuel, coal char and water vapor may be added to the carbon capture reactor at the same time, and water vapor may be used as a gasifying agent to promote the gasification of coal char.

[0037] In the present invention, in order to prevent the fuel from mixing into other reactors, the oxygen carrier CaSO4 in the carbon capture reactor should be appropriately excessive. In a preferred embodiment, the amount of CaSO4 and fuel input into the carbon capture reactor satisfies: the ratio of the molar number of CaSO4 to the molar number of carbon in the fuel is greater than 1:2 (which can be expressed as: X S / C >1 / 2,X S / C is the sulfur-carbon molar ratio). Under ideal reaction conditions, X S / C Should be equal to 1 / 2. Due to thermodynamic and reaction kinetic constraints, this value must be greater than 1 / 2, and the specific value should be obtained through experiments. C is the number of moles of the element in the fuel oxidized by the oxygen carrier, and accordingly, X S / C The theoretical value of X also varies with the oxidized element. S / C The initial value can be adjusted by varying the amount of CaSO4 and CaS in the whole system.

[0038] In the present invention, in order to improve the flue gas carbon capture rate, it is necessary to ensure that the CaO in the carbon capture reactor is moderately excessive. In a preferred embodiment, the amount of CaO, fuel and flue gas input into the carbon capture reactor satisfies: the ratio of the molar number of CaO to the total molar number of carbon in the fuel and the carbon in the flue gas is greater than 1 (which can be expressed as: X Ca / C >1,X Ca / C is the calcium-carbon molar ratio). Under ideal reaction conditions, X Ca / C Should be equal to 1. Due to thermodynamic and reaction kinetic constraints, this value must be greater than 1, and the specific value should be obtained through experiments. Ca / C It can be adjusted by changing the amount of CaCO3 and CaO in the whole system.

[0039] In the system described in the present invention, the reaction occurring in the calcination reactor is mainly the decomposition reaction of CaCO3. In this process, the heat required for the decomposition reaction is provided by the heat carried by the reaction products of the air reactor. The decomposition reaction of CaCO3 obtains high-purity carbon dioxide. Therefore, in this process, it is possible to avoid using electric heating or introducing air / oxygen to burn with fuel, which results in a huge waste of high-grade energy and the doping and dilution of the exported CO2. What is obtained after the reaction in the calcination reactor is mainly a solid mixture containing CaSO4, CaS and CaO. A part of the solid mixture enters the carbon capture reactor to participate in the reaction, and a part enters the air reactor to react.

[0040] In one embodiment, the calcination reactor is provided with a solid material replenishment inlet for replenishing at least one solid material among CaSO4, CaS, CaCO3 and CaO into the calcination reactor; its purposes include but are not limited to: 1) replenishing the loss of CaSO4 and CaS due to side reactions; 2) replenishing the loss of reaction materials caused by discharge of CaSO4, CaS, CaCO3 and CaO from the ash discharge port after wear; 3) adjusting the proportion of reaction materials in the system.

[0041] In the present invention, the calcination reactor can be a conventional choice in the art. In one embodiment, the calcination reactor is provided with a gas outlet for discharging carbon dioxide generated by decomposing CaCO3. The high-purity carbon dioxide obtained by decomposing CaCO3 in the calcination reactor can be discharged from the calcination reactor to achieve separation of CO2 and collect and reuse. In the present invention, since the solid material may contain moisture, the gas discharged from the calcination reactor may contain CO2 and water.

[0042] The CaS, CaSO4 and CaO from the calcination reactor are divided into two streams, one of which enters the carbon capture reactor and the other enters the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO enters the calcination reactor from the air reactor.

[0043] In the present invention, the reaction in the air reactor is mainly that the CaS from the calcination reactor and the excess air introduced from the outside undergo a violent redox reaction and release a large amount of heat, thereby obtaining a solid stream mainly containing CaSO4, CaO and ash carrying a large amount of heat, which is transported to the calcination reactor as a heat carrier to provide heat for the decomposition of CaCO3. In one embodiment, the gas after the reaction is discharged from the top of the air reactor in the form of a second tail gas.

[0044] In the present invention, the air reactor can be a conventional choice in the art. In one embodiment, the air reactor is provided with an ash discharge port, the functions of which include but are not limited to: 1) discharging fuel ash, abraded reactants, etc. in the system; 2) the ash discharge port is arranged in the air reactor instead of the carbon capture reactor to avoid discharging fuel to improve thermal efficiency; 3) the ash discharge port is arranged in the air reactor instead of the calcination reactor to avoid pollution caused by discharging CaS.

[0045] In the present invention, in order to avoid pollution caused by the discharge of CaS and reduce the heat loss of emptying and the energy consumption of induced draft caused by excessive air volume, it is necessary to ensure that the air in the air reactor is moderately excessive. In a preferred embodiment, the amount of air and CaS input into the air reactor satisfies: the ratio of the number of moles of oxygen in the air to the number of moles of CaS>2 (which can be expressed as: X O / S >2,X O / S is the oxygen-sulfur molar ratio). O / S The specific value should be obtained through experiments. O / S The value can be adjusted by changing the inlet air volume.

[0046] In the system described in the present invention, solid materials composed of decarbonized calcium circulating materials (CaO / CaCO3), calcium-based chemical chaining combustion circulating materials (CaS / CaSO4) and possible fuel ash mixture are circulated among the three reactors of carbon capture reactor, calcination reactor and air reactor. Carbon capture of flue gas is achieved through calcium circulation (CaO / CaCO3), avoiding the shortcomings of amine liquid degradation and amine escape when using amine absorbents in traditional flue gas carbon capture schemes; heat supply for the calcium circulation carbon capture process is achieved by calcium-based chemical chaining combustion (CaS / CaSO4), naturally avoiding the doping and dilution of CO2 product gas and saving high-grade electricity; the recycled calcium-based materials are widely available and low-priced, further saving the cost of flue gas carbon capture.

[0047] The present invention also provides a method for capturing carbon dioxide based on calcium circulation and calcium-based chemical chaining combustion, which is implemented in the system described above and comprises the following steps:

[0048] The CaS, CaO and CaSO4 in the calcination reactor are input into the carbon capture reactor, the fuel is input into the carbon capture reactor to react with CaSO4 to generate CO2 and CaS, and the CO2 generated by the reaction of the fuel with CaSO4 and the CO2 in the flue gas react with CaO in the carbon capture reactor to generate CaCO3;

[0049] The CaS and CaCO3 in the carbon capture reactor are input into the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO in the air reactor is input into the calcination reactor, and the CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0050] The CaS, CaSO4 and CaO in the calcination reactor are divided into two streams, one of which is input into the carbon capture reactor and the other is input into the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO is input from the air reactor into the calcination reactor.

[0051] In the method described in the present invention, two reactions mainly occur in the carbon capture reactor. The first reaction is that the fuel introduced from the outside reacts with the oxygen carrier CaSO4 from the calcination reactor to generate CO2 and CaS. During the reaction, the fuel can first undergo a gasification reaction with CO2, and the obtained product CO then reacts with the oxygen carrier CaSO4 to generate CaS and CO2. The fuel can also directly react with the oxygen carrier CaSO4 to generate CaS and CO2. The second reaction is that the CaO from the calcination reactor reacts with CO2 to generate CaCO3, wherein a part of the CO2 comes from the CO2 in the flue gas, and a part comes from the CO2 generated by the reaction of the fuel and the oxygen carrier CaSO4. After the reaction in the carbon capture reactor, a solid mixture mainly containing CaS and CaCO3 is obtained, which is input into the calcination reactor, and the decarbonized flue gas is discharged from the top of the carbon capture reactor in the form of the first tail gas. In the method described in the present invention, the reaction occurring in the calcination reactor is mainly the decomposition reaction of CaCO3. In this process, the heat required for the decomposition reaction is provided by the heat carried by the reaction products of the air reactor, and the decomposition reaction of CaCO3 obtains high-concentration carbon dioxide. Therefore, in this process, it is possible to avoid the use of electric heating or the introduction of air / oxygen and fuel combustion, which leads to a huge waste of high-grade energy and the doping and dilution of the exported CO2. After the reaction in the calcination reactor, a solid mixture mainly containing CaSO4, CaS and CaO is obtained. A part of the solid mixture enters the carbon capture reactor to participate in the reaction, and a part enters the air reactor to react. In the present invention, the reaction in the air reactor is mainly that the CaS from the calcination reactor undergoes a violent redox reaction with the excess air introduced from the outside and releases a large amount of heat, thereby obtaining a solid flow mainly containing CaSO4, CaO and ash carrying a large amount of heat. The solid flow is transported to the calcination reactor as a heat carrier to provide heat for the decomposition of CaCO3, and the gas after the reaction is discharged from the top of the air reactor in the form of a second tail gas.

[0052] In the present invention, in order to prevent the fuel from mixing into other reactors, the oxygen carrier CaSO4 in the carbon capture reactor should be appropriately excessive. In a preferred embodiment, the amount of CaSO4 and fuel input into the carbon capture reactor satisfies: the ratio of the molar number of CaSO4 to the molar number of carbon element in the fuel is greater than 1:2.

[0053] In the present invention, in order to improve the flue gas carbon capture rate, it is necessary to ensure that there is a moderate excess of CaO in the carbon capture reactor. In a preferred embodiment, the amounts of CaO, fuel and flue gas input into the carbon capture reactor satisfy: the ratio of the number of moles of CaO to the total number of moles of carbon in the fuel and the carbon in the flue gas is greater than 1.

[0054] In the present invention, in order to avoid pollution caused by discharging CaS and reduce the heat loss of emptying and the energy consumption of induced draft caused by excessive air volume, it is necessary to ensure that the air in the air reactor is moderately excessive. In a preferred embodiment, the amount of air and CaS input into the air reactor satisfies: the ratio of the number of moles of oxygen element in the air to the number of moles of CaS>2.

[0055] In another embodiment of the present invention, the reaction of the CaSO4 oxygen carrier with the fuel and the carbon capture reaction occur in two reactors respectively, that is, the carbon capture reactor is divided into a fuel reactor and a carbon capture reactor. Figure 2 This embodiment still utilizes mixed solid materials to transfer oxygen carrier combustion heat to supply CaO regeneration in the calcium-based carbon capture process.

[0056] The following examples further illustrate the carbon dioxide capture system and method based on calcium cycle and calcium-based chemical chaining combustion of the present invention. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0057] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0058] The following examples are Figure 1 Implementation in a CO2 capture system based on calcium cycle and calcium-based chemical looping combustion as shown:

[0059] The system includes a carbon capture reactor, a calcination reactor and an air reactor;

[0060] CaS, CaO and CaSO4 from the calcination reactor enter the carbon capture reactor, fuel enters the carbon capture reactor and reacts with CaSO4 to generate CO2 and CaS, CO2 generated by the reaction of fuel and CaSO4 and CO2 from flue gas react with CaO in the carbon capture reactor to generate CaCO3;

[0061] CaS and CaCO3 from the carbon capture reactor enter the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO from the air reactor enters the calcination reactor, and CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0062] The CaS, CaSO4 and CaO from the calcination reactor are divided into two streams, one of which enters the carbon capture reactor and the other enters the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid stream carrying heat and containing CaSO4 and CaO enters the calcination reactor from the air reactor;

[0063] The calcining reactor is provided with a solid material supplement inlet for supplementing at least one solid material selected from the group consisting of CaSO4, CaS, CaCO3 and CaO into the calcining reactor; the calcining reactor is provided with a gas outlet for discharging carbon dioxide generated by decomposition of CaCO3;

[0064] The amounts of CaSO4 and fuel input into the carbon capture reactor satisfy: the ratio of the number of moles of CaSO4 to the number of moles of carbon in the fuel is 1:1;

[0065] The amounts of CaO, fuel and flue gas input into the carbon capture reactor satisfy: the ratio of the number of moles of CaO to the total number of moles of carbon in the fuel and the carbon in the flue gas is 1:0.5;

[0066] The amounts of air and CaS input into the air reactor satisfy that the ratio of the molar number of oxygen element in the air to the molar number of CaS is 3:1.

[0067] Example 1

[0068] The CaS, CaO and CaSO4 in the calcination reactor are input into the carbon capture reactor (fixed bed reactor), the coal char and water vapor are input into the carbon capture reactor to react with CaSO4 to generate CO2 and CaS, and the CO2 generated by the reaction of the coal char and CaSO4 and the CO2 in the flue gas react with CaO in the carbon capture reactor to generate CaCO3;

[0069] The CaS and CaCO3 in the carbon capture reactor are input into the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO in the air reactor is input into the calcination reactor, and the CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0070] The CaS, CaSO4 and CaO in the calcination reactor are divided into two streams, one of which is input into the carbon capture reactor and the other is input into the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO is input from the air reactor into the calcination reactor.

[0071] In this embodiment, the concentration of carbon dioxide discharged from the gas outlet of the calcining reactor can reach more than 95 vol% after condensation and dust reduction.

[0072] Regarding the energy-saving effect of this embodiment, in the current mainstream chemical absorption carbon capture technology, heating the composite amine absorbent to reproduce CO2 requires a large amount of electricity or high-grade steam, and the system energy consumption is relatively high. According to public data reports, the energy consumption of the process of heating to generate 1 ton of CO2 is no less than 2.45GJ (about 681kWh in terms of electricity). In this embodiment, because a carbon dioxide capture system with calcium circulation and calcium-based chemical chain combustion is used, the electricity or steam consumption of the absorbent regeneration process in the mainstream chemical absorption carbon capture technology is avoided.

[0073] Regarding the environmental protection effect of this embodiment, the composite amine absorbent in the current mainstream chemical absorption carbon capture technology has performance degradation and shortened life due to degradation during long-term circulation operation, as well as environmental pollution caused by amine escape. According to literature reports, the average loss of amine solvent is about 2 kg for capturing 1 ton of CO2 in this type of carbon capture device in operation in China. In this embodiment, because the carbon dioxide capture system of calcium circulation and calcium-based chemical chain combustion is adopted, the use of composite amine solution is avoided, and there is no problem of using, recycling and disposing of hazardous chemicals, which has obvious environmental advantages.

[0074] Example 2

[0075] The CaS, CaO and CaSO4 in the calcination reactor are input into the carbon capture reactor (moving bed reactor), natural gas (mainly methane) is input into the carbon capture reactor to react with CaSO4 to generate CO2 and CaS, and CO2 generated by the reaction of coal char with CaSO4 and CO2 in flue gas react with CaO in the carbon capture reactor to generate CaCO3;

[0076] The CaS and CaCO3 in the carbon capture reactor are input into the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO in the air reactor is input into the calcination reactor, and the CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0077] The CaS, CaSO4 and CaO in the calcination reactor are divided into two streams, one of which is input into the carbon capture reactor and the other is input into the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO is input from the air reactor into the calcination reactor.

[0078] In this embodiment, the concentration of carbon dioxide discharged from the gas outlet of the calcining reactor can reach more than 95 vol% after condensation and dust reduction.

[0079] Regarding the energy-saving effect of this embodiment, in the current mainstream chemical absorption carbon capture technology, heating the composite amine absorbent to reproduce CO2 requires a large amount of electricity or high-grade steam, and the system energy consumption is relatively high. According to public data reports, the energy consumption of the process of heating to generate 1 ton of CO2 is no less than 2.45GJ (about 681kWh in terms of electricity). In this embodiment, because a carbon dioxide capture system with calcium circulation and calcium-based chemical chain combustion is used, the electricity or steam consumption of the absorbent regeneration process in the mainstream chemical absorption carbon capture technology is avoided.

[0080] Regarding the environmental protection effect of this embodiment, the composite amine absorbent in the current mainstream chemical absorption carbon capture technology has performance degradation and shortened life due to degradation during long-term circulation operation, as well as environmental pollution caused by amine escape. According to literature reports, the average loss of amine solvent is about 2 kg for capturing 1 ton of CO2 in this type of carbon capture device in operation in China. In this embodiment, because the carbon dioxide capture system of calcium circulation and calcium-based chemical chain combustion is adopted, the use of composite amine solution is avoided, and there is no problem of using, recycling and disposing of hazardous chemicals, which has obvious environmental advantages.

[0081] Example 3

[0082] The CaS, CaO and CaSO4 in the calcination reactor are input into the carbon capture reactor (fluidized bed reactor), the synthesis gas (composition includes carbon monoxide and hydrogen) is input into the carbon capture reactor to react with CaSO4 to generate CO2 and CaS, and the CO2 generated by the reaction of coal char with CaSO4 and the CO2 in the flue gas are reacted with CaO in the carbon capture reactor to generate CaCO3;

[0083] The CaS and CaCO3 in the carbon capture reactor are input into the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO in the air reactor is input into the calcination reactor, and the CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO;

[0084] The CaS, CaSO4 and CaO in the calcination reactor are divided into two streams, one of which is input into the carbon capture reactor and the other is input into the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO is input from the air reactor into the calcination reactor.

[0085] In this embodiment, the concentration of carbon dioxide discharged from the gas outlet of the calcining reactor can reach more than 95 vol% after condensation and dust reduction.

[0086] Regarding the energy-saving effect of this embodiment, in the current mainstream chemical absorption carbon capture technology, heating the composite amine absorbent to reproduce CO2 requires a large amount of electricity or high-grade steam, and the system energy consumption is relatively high. According to public data reports, the energy consumption of the process of heating to generate 1 ton of CO2 is no less than 2.45GJ (about 681kWh in terms of electricity). In this embodiment, because a carbon dioxide capture system with calcium circulation and calcium-based chemical chain combustion is used, the electricity or steam consumption of the absorbent regeneration process in the mainstream chemical absorption carbon capture technology is avoided.

[0087] Regarding the environmental protection effect of this embodiment, the composite amine absorbent in the current mainstream chemical absorption carbon capture technology has performance degradation and shortened life due to degradation during long-term circulation operation, as well as environmental pollution caused by amine escape. According to literature reports, the average loss of amine solvent is about 2 kg for capturing 1 ton of CO2 in this type of carbon capture device in operation in China. In this embodiment, because the carbon dioxide capture system of calcium circulation and calcium-based chemical chain combustion is adopted, the use of composite amine solution is avoided, and there is no problem of using, recycling and disposing of hazardous chemicals, which has obvious environmental advantages.

[0088] Comparative Example 1

[0089] In the current mainstream chemical absorption carbon capture technology, heating the composite amine absorbent to reproduce CO2 requires a large amount of electricity or high-grade steam, and the system energy consumption is high. According to public data reports, the energy consumption of the heating process to generate 1 ton of CO2 is no less than 2.45GJ (about 681kWh in terms of electricity). In this embodiment, because a carbon dioxide capture system with calcium circulation and calcium-based chemical chaining combustion is used, the electricity or steam consumption of the absorbent regeneration process in the mainstream chemical absorption carbon capture technology is avoided.

[0090] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A carbon dioxide capture system based on calcium cycle and calcium-based chemical chaining combustion, characterized in that: The system includes a carbon capture reactor, a calcination reactor and an air reactor; CaS, CaO and CaSO4 from the calcination reactor enter the carbon capture reactor, fuel enters the carbon capture reactor and reacts with CaSO4 to generate CO2 and CaS, CO2 generated by the reaction of fuel and CaSO4 and CO2 from flue gas react with CaO in the carbon capture reactor to generate CaCO3; CaS and CaCO3 from the carbon capture reactor enter the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO from the air reactor enters the calcination reactor, and CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO; The CaS, CaSO4 and CaO from the calcination reactor are divided into two streams, one of which enters the carbon capture reactor and the other enters the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO enters the calcination reactor from the air reactor.

2. The system according to claim 1, characterized in that The carbon capture reactor is selected from a fixed bed reactor, a moving bed reactor, a spouted bed reactor, a fluidized bed reactor or a transport bed reactor.

3. The system according to claim 1 or 2, characterized in that: The fuel entering the carbon capture reactor may be a gaseous fuel and / or a solid fuel; Preferably, the fuel is selected from at least one of coal tar, coal, natural gas, synthesis gas and coke oven gas.

4. The system according to claim 3, characterized in that When the fuel entering the carbon capture reactor is coal char, the coal char and water vapor enter the carbon capture reactor at the same time.

5. The system according to any one of claims 1 to 4, characterized in that: The calcining reactor is provided with a solid material supplement inlet for supplementing at least one solid material selected from the group consisting of CaSO4, CaS, CaCO3 and CaO into the calcining reactor.

6. The system according to any one of claims 1 to 5, characterized in that: The calcining reactor is provided with a gas outlet for discharging carbon dioxide generated by the decomposition of CaCO3.

7. A method for capturing carbon dioxide based on calcium cycle and calcium-based chemical chaining combustion, characterized in that: The method is implemented in the system according to any one of claims 1 to 6, and the method comprises the following steps: The CaS, CaO and CaSO4 in the calcination reactor are input into the carbon capture reactor, the fuel is input into the carbon capture reactor to react with CaSO4 to generate CO2 and CaS, and the CO2 generated by the reaction of the fuel with CaSO4 and the CO2 in the flue gas react with CaO in the carbon capture reactor to generate CaCO3; The CaS and CaCO3 in the carbon capture reactor are input into the calcination reactor, and the solid stream carrying heat and containing CaSO4 and CaO in the air reactor is input into the calcination reactor, and the CaCO3 is decomposed into CO2 and CaO under the action of the heat carried by the solid stream containing CaSO4 and CaO; The CaS, CaSO4 and CaO in the calcination reactor are divided into two streams, one of which is input into the carbon capture reactor and the other is input into the air reactor. CaS reacts with air in the air reactor to generate CaSO4 and release heat. The solid flow carrying heat and containing CaSO4 and CaO is input from the air reactor into the calcination reactor.

8. The method according to claim 7, characterized in that The amounts of CaSO4 and fuel input into the carbon capture reactor satisfy: the ratio of the number of moles of CaSO4 to the number of moles of carbon in the fuel is greater than 1:

2.

9. The method according to claim 7 or 8, characterized in that: The amounts of CaO, fuel and flue gas input into the carbon capture reactor satisfy: the ratio of the number of moles of CaO to the total number of moles of carbon in the fuel and the carbon in the flue gas is greater than 1.

10. The method according to any one of claims 7 to 9, characterized in that: The amounts of air and CaS input into the air reactor satisfy: the ratio of the molar number of oxygen element in the air to the molar number of CaS>2.

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