Multi-stage carbon dioxide capturing and utilizing method and device

Abstract

The invention discloses a multi-stage carbon dioxide capture and utilization method and device. CO2-containing high-temperature flue gas enters an adsorption reactor and passes through the adsorption reactor filled with a bifunctional catalyst, and CO2 in the flue gas is adsorbed and captured by a catalytic material in a catalyst bed layer; decarburized gas comes out of the adsorption reactor, exchanges heat with process gas from the conversion reactor in a heat exchanger, and enters the next stage of adsorption reactor after heat exchange, when the adsorption reactor reaches the saturated adsorption capacity of an adsorbent, CO2-containing high-temperature flue gas is switched to enter the first stage of conversion reactor, at the moment, reducing gas enters the adsorption reactor, and the CO2-containing high-temperature flue gas enters the second stage of conversion reactor; and the converted synthesis gas is sent out of the device. By means of the technical process, the energy utilization rate can be fully increased, the emission reduction cost can be effectively reduced, high energy consumption caused by trapping cooling / conversion heating can be avoided, and the problems of high cost for purification and transportation after CO2 capture and potential safety hazards caused by burying are solved.

Description

Technical Field

[0001] The present invention relates to a method for capturing carbon dioxide from high-temperature gas and converting it into synthesis gas (synthesis gas here and hereinafter refers to CO or a mixture of CO and hydrogen, water vapor, etc.), and specifically to a multi-stage carbon dioxide capture and utilization method and a reactor thereof. Background Technology

[0002] Carbon capture, utilization and storage (CCUS) is the most important technical path to address global climate change and control greenhouse gas emissions. The Central Economic Work Conference listed it as one of the eight key tasks for 2021. This "new climate goal" will trigger a huge change in my country's energy structure. CO 2 There are many sources of CO emissions, such as cement, steel, electricity, coal chemical industry and refineries. 2 Major emitters. Targeting CO 2 Emissions issues, all industries have carried out CO 2 's research and exploration on the capture, utilization and storage of CO, and each industry has formed a variety of CO 2 Technical methods for capture, utilization and storage.

[0003] Currently, the focus of large-scale research on carbon capture is on the power industry. Among them, the chemical absorption capture method for flue gas after combustion in coal-fired power plants is a relatively mature technology. However, high-temperature flue gas requires step-by-step heat exchange to be absorbed at low temperatures, and its high solvent cost and high regeneration energy consumption cause the energy consumption of coal-fired power plants to increase by about 30%. At the same time, the captured CO 2 Storing in a different place requires high transportation costs, and the potential safety hazards are also questioned. The adsorption method is also relatively mature in technology, but it is generally only used in working conditions where the gas composition is determined. The capacity of the adsorbent and CO 2 The selectivity is low, the cost is high, and it is generally only used for low-temperature gases. Membrane methods usually cannot achieve a high degree of separation and require multiple stages and / or recycling, which leads to increased complexity, energy consumption and cost. At the same time, impurities in the gas may also cause blockage. After the above methods are captured, only high-concentration CO 2 Gas, subsequent transportation and utilization are also issues worthy of attention. Development of CO 2 Capture and conversion into high value-added chemicals is the key.

[0004] ​In recent years, with the strong support of the Chinese government, enterprises, scientific research institutions and universities have jointly participated in a series of studies on supporting policies, related theories and key technologies, established a professional research team, and achieved a number of results and progress. The specific situation of major domestic industrial pilot and demonstration projects is as follows: The CO 2 The capture demonstration project uses CO 2 Capture technology, CO captured annually 2 Scale reaches 120,000 tons, capturing CO 2 Purity reaches over 99.5%. Captured CO 2 Part of it is used in the food processing industry after passing through the refining system, and the rest is used in industrial production. When it was put into operation, the capture device was the largest coal-fired power plant flue gas CO 2 Capture device. The 250MW IGCC unit of Huaneng Tianjin Green Coal Power was completed and put into operation in 2011, and the 400MW capacity was completed in 2016 and equipped with CO 2 IGCC unit with capture device, the demonstration project aims to research, develop, demonstrate and promote CO 2 Near-zero emission coal-based power generation system can significantly improve power generation efficiency and master the design, construction and operation technology of large-scale coal gasification projects.

[0005] Three companies have established calcium cycle CO capture 2 pilot demonstration, including the flue gas CO of La Pereda, Spain's 1.7MWth power plant 2 Capture demonstration system, flue gas CO from Darmstadt's 1MWth power plant in Germany 2 Capture demonstration system, 3kWth power plant flue gas CO 2 In the pilot capture, the calcium circulating double fluidized bed circulating capture system was used to achieve CO 2 Capture and regeneration.

[0006] All of the above technologies focus on CO 2 In terms of capture, it does not involve conversion and subsequent utilization. The published patents on CO 2 Research on capture and conversion is mostly focused on catalysts. 2 Capture is a highly exothermic reaction, and the conversion process is a highly endothermic reaction. The temperature and heat control of the reaction process is extremely critical. The design of the process and the type of reactor are the key to determining whether the technology is feasible. For highly endothermic and exothermic reactions, the measures usually taken include: using coils to take heat / supplement heat, using direct combustion heating, using fluidized beds, moving beds, etc. These methods are used for CO 2 ​There are some problems in both capture and conversion. In terms of using coil pipes for heat extraction / supplementation, on the one hand, with the switching of the capture / conversion process, the coil pipes absorb heat and extract heat alternately, making control difficult. On the other hand, due to the uneven reaction in the catalyst bed, it is difficult to avoid local overheating / overcooling. When using direct supplementary combustion heating, there is often a problem of local overheating in the catalyst bed. Taking the commonly used CaO / CaCO 3 adsorbent as an example, when the temperature > 850 - 900 °C, the adsorbent will melt and sinter, while the CO 2 conversion process generally requires a reaction temperature above 500 - 700 °C. If direct supplementary combustion heating is used, the temperature is too high, and the adsorbent will melt, sinter and deactivate; if the temperature is controlled below 800 °C, due to the temperature difference limitation, the supplementary heat quantity is very limited, or too much fuel gas and combustion-supporting gas need to be supplemented, resulting in serious dilution of the product and a decrease in the effective gas concentration. If forms such as fluidized bed and moving bed are used, since most industrial flue gases are at atmospheric pressure or low pressure, it is basically impossible to achieve with conventional means due to pressure limitations.

[0007] Chinese Patent CN202110287520.5 discloses a method for synthesizing syngas by reducing carbon monoxide with a high-temperature molten heat carrier, carbon dioxide and carbon powder. This method uses carbon dioxide and carbon powder to absorb the sensible heat and latent heat emitted by the high-temperature heat carrier and heat up to the reduction temperature to instantaneously reduce it into high-energy syngas of carbon monoxide, and uses the high-temperature volume specific heat capacity of carbon dioxide to conduct cyclic heat exchange with the granulated high-temperature heat carrier. The whole process has a long flow, and the core equipment is similar to a fluidized bed, with a large pressure drop. The process temperature changes frequently between 50 °C and 1500 °C. The drastic temperature change will inevitably bring energy consumption problems; and the long flow will also bring problems of pressure drop. Usually, the pressure of the flue gas is low, and the large pressure drop also limits the use of this technology.

[0008] Chinese Patent CN201821322948.9 discloses a catalytic reaction device, which is provided with a methane + steam hydrogen production catalyst at the lower part to produce hydrogen, carbon dioxide is introduced in the middle part, and a carbon dioxide hydrogenation catalyst is provided at the upper part. Carbon dioxide reacts with hydrogen to produce carbon monoxide gas at the top. The main problems of this patent are: First, carbon dioxide hydrogenation is a strongly endothermic reaction. For every 5% reaction of the equivalent ratio of CO 2 and H 2 it will cause a temperature drop of about 150 °C. In the form of this reactor, the reaction cannot actually be self-sustaining and will soon terminate due to temperature reduction; Second, this reactor does not involve carbon capture and is just a carbon dioxide hydrogenation reactor.

[0009] Chinese Patent CN201410202280.4 discloses a method based on a manganese and lanthanide metal catalyst for hydrogenating carbon dioxide to carry out the reverse water-gas shift reaction to produce carbon monoxide. The main problems of this patent are similar to those of CN201821322948.9. First of all, the hydrogenation of carbon dioxide is a strongly endothermic reaction. For every 5% reaction of the equivalent ratio of CO 2 and H 2 it will cause a temperature drop of about 150 °C. Under the type of this reactor, the reaction actually cannot be self-sustaining and will soon terminate due to temperature reduction; secondly, this reactor does not involve carbon capture and is only a carbon dioxide hydrogenation reactor.

[0010] Currently, the patents, literature, etc. publicly available at home and abroad focus on aspects of CO 2 capture and research on the reverse water-gas shift reaction of CO 2 hydrogenation, while there is little research on aspects of CO 2 capture and in-situ conversion. Carrying out efficient CO 2 capture at high temperature and in-situ conversion of the captured CO 2 into syngas products, so as to facilitate the subsequent synthesis of high-value-added chemical products such as light olefins, can not only fully improve energy utilization efficiency, effectively reduce emission reduction costs, but also avoid the high energy consumption of capture cooling / conversion heating, solve the high costs of purification and transportation after CO 2 capture, as well as the potential safety hazards brought by storage, and is expected to improve the feasibility and economy of the entire CO 2 emission reduction process, which has important significance. Summary of the Invention

[0011] To solve the above problems, the object of the present invention is to provide a multi-stage carbon dioxide capture and utilization method and its reactor in view of the deficiencies of the above-mentioned prior art, so as to capture CO2 from high-temperature gas and in-situ convert it into syngas.

[0012] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0013] A multi-stage carbon dioxide capture and utilization method, characterized in that the method comprises the following steps:

[0014] 1) High-temperature flue gas containing CO 2 enters the adsorption reactor and passes through the adsorption reactor filled with a bifunctional catalyst. The CO 2 in the flue gas is adsorbed and captured by the catalytic material in the catalyst bed, and the heat generated during the adsorption reaction process is absorbed by the heat storage body in the catalyst bed;

[0015] 2) The gas after decarbonization in step 1) exits the adsorption reactor, exchanges heat with the process gas coming from the conversion reactor in the heat exchanger, and then enters the next-stage adsorption reactor, and the CO2 It is further adsorbed and trapped by the catalytic material in the catalyst bed, and the heat generated during the adsorption reaction is absorbed by the heat storage body in the catalyst bed. The gas after reaching the decarbonization standard exits the adsorption reactor and is discharged after waste heat recovery;

[0016] 3) When the adsorption reactor reaches the saturated adsorption capacity of the adsorbent, the CO-containing 2 The high-temperature flue gas is switched to enter the first-stage conversion reactor. At this time, the reducing gas enters the adsorption reactor and passes through the catalyst bed of the adsorption reactor. The catalytic material that has adsorbed CO 2 reacts with the reducing gas, and carbon dioxide is reduced to CO. The heat required for the conversion reaction is jointly provided by the heat storage body after endothermic in step 1) and the gas after decarbonization through heat exchange with the heat exchanger after the first-stage adsorption reaction; The process gas enters the next-stage conversion reactor for further conversion, and the syngas after the conversion is sent out of the device;

[0017] 4) When the conversion reactor reaches the expected saturated adsorption capacity of the adsorbent, the functions of the conversion reactor and the adsorption reactor are interchanged by switching the feed. The CO-containing 2 The high-temperature flue gas is switched to enter the adsorption reactor again, and the reducing gas is switched to enter the conversion reactor, and the above steps are repeated.

[0018] A multi-stage carbon dioxide capture and utilization method of the present invention is further characterized in that: the process gas described in steps 2) and 3) refers to the reducing gas containing syngas in the conversion reactor.

[0019] A multi-stage carbon dioxide capture and utilization method of the present invention is further characterized in that: both the catalyst beds of the adsorption reactor and the conversion reactor are filled with catalytic materials and heat storage bodies. The catalytic material refers to a material with dual functions of carbon dioxide adsorption and catalytic conversion, and the heat storage body refers to a material with a heat storage function.

[0020] A multi-stage carbon dioxide capture and utilization method of the present invention is further characterized in that: the reducing gas refers to one or more mixtures of gases that can react with CO 2 to generate CO, or a mixture of these gases and inert gases (such as nitrogen).

[0021] A multi-stage carbon dioxide capture and utilization method of the present invention is further characterized in that: the adsorption reaction temperature in step 2) is room temperature to 800 °C, preferably in the temperature range of 600 to 750 °C; the process gas described here refers to the reducing gas containing syngas in the conversion reactor, and further at least two conversion reactors are described here.

[0022] A multi-stage carbon dioxide capture and utilization method of the present invention is further characterized in that: in step 3), the adsorbed CO 2The catalytic material reacts with the reducing gas, and carbon dioxide is reduced to CO. At this time, the temperature of the catalyst bed and the gas decreases. The reducing gas containing syngas passing through the first-stage conversion reactor exchanges heat with the high-temperature CO gas in step 1), and the temperature rises. The insufficient part of the heat can be supplemented by a heater or other external heat sources. 2 After heat exchange, the temperature rises, and the insufficient part of the heat can be supplemented by a heater or other external heat sources.

[0023] A multi-stage carbon dioxide capture and utilization method of the present invention is further characterized in that: the conversion reaction temperature is 100-950 °C, and the preferred temperature range is 600-800 °C;

[0024] The adsorption reactor and the conversion reactor in the present invention are the same, and it is only for the convenience of narration in the present invention. Both the adsorption reactor and the conversion reactor are fixed-bed reactors, which can be single or multiple. The single reactor refers to the way of overlapping arrangement or being separated by a partition in the same shell. The catalyst bed is filled with catalytic material and heat storage body. The catalytic material refers to a material with dual functions of carbon dioxide adsorption and catalytic conversion, such as CaO material loaded with one or more active components such as Co, Ni, and lanthanide metals; the heat storage body refers to a material with heat storage function, such as corundum, ceramics, mullite, zircon, or cordierite.

[0025] The gas that can react with CO 2 to generate CO refers to H 2 , CH 4 and C 2 H 6 and so on. When these gases are introduced separately, the following reactions will occur:

[0026] CO 2 +2H 2 =CO+H 2 O+H 2 or CO 2 +H 2 =CO+H 2 O

[0027] CO 2 +CH 4 =2CO+2H 2

[0028] 2CO 2 +C 2 H 6 =4CO+3H 2

[0029] The present invention also provides a multi-stage carbon dioxide capture and utilization device for implementing the above carbon dioxide capture and utilization method, specifically:

[0030] A multi-stage carbon dioxide capture and utilization device mainly includes an adsorption reactor, a conversion reactor and a heat exchanger, and is characterized in that: catalytic materials and heat storage bodies are simultaneously filled in the catalyst beds of the adsorption reactor and the conversion reactor; the adsorption reactor is a two-stage adsorption, and the conversion reactor is also a two-stage conversion; during the adsorption reaction process, the first-stage adsorption reactor is connected to high-temperature CO 2 flue gas at the upper part and the heat exchanger at the lower part; the second-stage adsorption reactor is connected to the purified flue gas at the lower part; during the conversion and regeneration process, the first-stage conversion reactor is connected to the reducing gas at the upper part and the heat exchanger at the lower part; the second-stage conversion reactor is connected to the synthesis gas at the lower part.

[0031] The multi-stage carbon dioxide capture and utilization device of the present invention is further characterized in that: an external heat supplement heater is also provided, and the external heat supplement heater is respectively connected to the second-stage conversion reactor and the heat exchanger. During the conversion and regeneration process, the external heat supplement heat exchanger is connected to the heat exchanger at the upper part and the second-stage conversion reactor at the lower part.

[0032] The multi-stage carbon dioxide capture and utilization device of the present invention is further characterized in that: both the adsorption reactor and the conversion reactor can be set with one or more reactors. When the adsorption reactor and the conversion reactor are set with multiple reactors, they can be switched simultaneously or independently one by one.

[0033] The multi-stage carbon dioxide capture and utilization device of the present invention is further characterized in that: both the adsorption reactor and the conversion reactor are fixed-bed reactors, which can be single or multiple. The single reactor means that multiple reactors are arranged in an overlapping manner or separated by partitions in the same shell to achieve multi-stage conversion. Catalytic materials and heat storage bodies are filled in the catalyst beds. The catalytic materials refer to materials with dual functions of carbon dioxide adsorption and catalytic conversion, such as CaO materials loaded with one or more of active components such as Co, Ni and lanthanide metals; the heat storage bodies refer to materials with heat storage functions, such as corundum, ceramics, mullite, zirconia or cordierite, etc.

[0034] The reactor of the present invention is further characterized in that: the reactor is a fixed-bed reactor, and the reactor type is bottom-in and top-out, top-in and bottom-out, side-in and side-out, outer-periphery-in and middle-out, middle-in and outer-periphery-out, etc.

[0035] The reactor of the present invention is further characterized in that: the catalytic materials and the heat storage bodies are compounded in a certain proportion. The filling method of the catalytic materials and the heat storage bodies in the catalyst bed is: the catalytic materials and the heat storage bodies are uniformly mixed in a certain proportion and then filled in the catalyst bed; or the catalytic materials and the heat storage bodies are filled layer by layer in the catalyst bed, that is, one layer of catalytic materials and one layer of heat storage bodies are filled in layers.

[0036] For the reactor of the present invention, the amount of the catalytic material A (m 3)Determined by the amount of carbon dioxide A1 (t / h) to be adsorbed, the material adsorption capacity A2 (t / m 3 ), and the designed switching time A3 (h). The specific calculation formula is as follows:

[0037] A = A1×A3 / A2

[0038] Where: A1 represents the amount of carbon dioxide to be adsorbed;

[0039] A2 represents the material adsorption capacity;

[0040] A3 represents the designed switching time.

[0041] The amount of the regenerator is jointly determined by the inlet temperature of the carbon dioxide-containing gas, the gas composition and specific heat, the heat released by the reaction of the adsorbed carbon dioxide, the amount and specific heat of the catalytic material, the specific heat of the regenerator, the heat loss of the reactor, the final temperature of the reactor bed layer to be controlled, etc.

[0042] To achieve the expected adsorption conditions (adsorbent saturated adsorption capacity) in the present invention, it can be time-sequentially controlled according to the designed switching time; it can be on-line controlled according to the carbon dioxide content in the gas after decarbonization; or other control methods can also be adopted.

[0043] The present invention is applicable to the treatment of carbon dioxide-containing gases (such as high-temperature flue gas, etc.) to capture CO 2 from the carbon dioxide-containing gas 2 and in-situ convert it into syngas. The optimal temperature range during the use of the present invention is room temperature to 800°C. When the temperature of the gas to be treated is too high, the temperature can be reduced to an appropriate temperature range by means of heat recovery, etc.; when the temperature is too low, the temperature can be raised to an appropriate temperature range by means of heating, etc.

[0044] The advantages of the present invention compared with the prior art are: 1) Carbon dioxide adsorption and conversion are completed in-situ under close temperature and pressure conditions, which can not only fully improve the energy utilization rate, effectively reduce the emission reduction cost, but also avoid the high energy consumption of capture cooling / transformation heating, and solve CO 2The high costs of purification and transportation after capture, as well as the safety hazards brought about by storage; 2) In the reactor of the present invention, since the heat exchange between the conversion process and the adsorption process is carried out continuously and evenly, problems such as "temperature runaway" and "local hot spots" that may cause equipment damage will not occur. The reactor is inherently safe and can completely avoid the possibility of overheating and damage of the reactor and catalytic materials caused by uneven reactions and accidental interruption of the heat exchange medium in traditional reactors; 3) The in-situ coupling utilization of the heat from the adsorption exotherm / conversion endotherm process can be achieved, saving more than 50% energy compared with existing reactors; 4) The reactor has a low pressure drop and can be applied to most flue gas conditions; 5) The process is simple, automatic sequential control can be realized, it is easy to operate and maintain, has low investment, small floor area and strong adaptability.

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of the present invention is not limited. Brief Description of the Drawings

[0046] Figure 1 is a schematic diagram of a multi-stage carbon dioxide capture and utilization method of the present invention;

[0047] Figure 2 is a schematic diagram of a multi-stage carbon dioxide capture and utilization method with external heat compensation heating of the present invention;

[0048] Figure 3 is a loading schematic diagram of uniform mixing of catalytic materials and regenerators in the reactor of the present invention.

[0049] The reference numerals shown in the drawings are:

[0050] 1 - Flue gas containing CO 2 High-temperature flue gas, 2 - Reducing gas, 3 - Decarbonized gas, 4 - Product syngas, 5 - Catalyst bed, 5-1 - Catalytic material, 5-2 Regenerator, 6 - Heat exchanger, 7, 8, 9, 10, 11, 12, 13, 14 - Control valves, 15 - 1# Conversion electric heater, 16 - 2# Conversion electric heater; 1# - First-stage adsorption reactor, 2# - Second-stage adsorption reactor, 3# - First-stage conversion reactor, 4# - Second-stage conversion reactor. Detailed Description of the Embodiment

[0051] As shown in the attached Figure 1 and attached Figure 2 figures, a multi-stage carbon dioxide capture and utilization method and device. The number of reactors is at least 4, with 2 in the adsorption reaction state and 2 in the conversion and regeneration state. When the first adsorption reaction is carried out, the reducing gas in the conversion reactor absorbs the adsorption reaction heat and passes through. After the first adsorption cycle ends, the conversion and regeneration process starts in the adsorption reactor, and the conversion reactor starts the adsorption reaction again. Since then, the adsorption reaction and the conversion reaction are carried out according to Figure 1The middle process reaches equilibrium. For the convenience of description, the adsorption reactor and the conversion reactor are used to illustrate the present invention. The reactor of the present invention can also be multiple, and some of the reactors are in the adsorption reaction state, and some of the reactors are in the conversion and regeneration state, that is, there can be multiple adsorption reactors and multiple conversion reactors. When multiple reactors are used, they can be switched simultaneously or independently one by one to reduce the impact on the upstream gas such as fluctuations; the reactor can also be a single one, and the internal part is divided into different functional areas by means of partitions and the like. Attached Figure 1 and attached Figure 2 The difference lies in attached Figure 2 A conversion electric heater with external heat compensation is provided.

[0052] For the convenience of description below, four reactors are taken as an example. As shown in attached Figure 1 and attached Figure 2 As shown, there are four reactors, two of which are adsorption reactors and the other two are conversion reactors. Before the start of the operation of the device, the control valves 7-14 are all in the closed state. The steps of its multi-stage carbon dioxide capture and utilization method are as follows:

[0053] 1) The control valves 7 and 11 are opened, and the high-temperature flue gas 1 containing CO 2 enters the first-stage adsorption reactor 1# through the control valve 7. The CO 2 in the flue gas is adsorbed and captured by the catalytic material in the catalyst bed 5, and the heat generated during the adsorption reaction is absorbed by the heat storage body in the catalyst bed.

[0054] 2) After decarbonization in step 1), the gas exchanges heat with the process gas from the first-stage conversion reactor 3# through the heat exchanger 6 and then enters the second-stage adsorption reactor 2# for further adsorption and capture of CO 2 The heat generated during the adsorption reaction is absorbed by the heat storage body in the catalyst bed. After the decarbonization reaches the standard, the gas 3 comes out of the second-stage adsorption reactor 2# through the control valve 11 and is discharged after waste heat recovery. At this time, the first-stage adsorption reactor 1# and the second-stage adsorption reactor 2# are in the adsorption state, and the adsorption reaction temperature is normal temperature to 800 °C, preferably in the range of 600-750 °C;

[0055] 3) When the first-stage adsorption reactor 1# and the second-stage adsorption reactor 2# reach the saturated adsorption capacity of the adsorbent, the control valves 7 and 11 are closed, the control valves 9 and 14 are opened, and the high-temperature flue gas 1 containing CO 2 switches to enter the first-stage conversion reactor 3# and the second-stage conversion reactor 4# through the control valve 9. At this time, the control valves 8 and 12 are opened. At this time, the reducing gas 2 enters the first-stage adsorption reactor 1# through the control valve 8, passes through the adsorption reactor bed 5, and adsorbs CO 2The catalytic material reacts with the reducing gas, and carbon dioxide is reduced to CO. The heat required for the conversion reaction is obtained from the heat storage body after heat absorption in step 1) and the process gas from the first-stage adsorption reactor 1# through the heat exchanger 6, and then enters the second-stage adsorption reactor 2# to continue the reduction reaction. The syngas 4 comes out of the second-stage adsorption reactor 4# through the control valve 12, and the syngas after the conversion is sent out of the device. At this time, the first-stage adsorption reactor 3# and the second-stage adsorption reactor 4# are in the conversion state, and the conversion reaction temperature is 100-950 °C, preferably in the range of 600-800 °C;

[0056] 4) The CO-containing gas entering the first-stage conversion reactor 3# and the second-stage conversion reactor 4# 2 The high-temperature flue gas sequentially passes through the catalyst bed layer of the conversion reactor, and the CO in the flue gas 2 is adsorbed and trapped by the catalytic material in the catalyst bed layer, and the heat generated during the adsorption reaction is absorbed by the heat storage body in the catalyst bed layer. The gas 3 after meeting the decarbonization standard comes out of the second-stage conversion reactor 4# through the control valve 14 and is discharged after waste heat recovery;

[0057] 5) When the first-stage conversion reactor 3# and the second-stage conversion reactor 4# reach the saturated adsorption capacity of the adsorbent, the conversion reactor and the adsorption reactor exchange functions, that is, the conversion reactor is used for the adsorption reaction, and the adsorption reactor is used for the conversion. At this time, the control valves 9 and 14 are closed, and 7 and 11 are opened. The CO-containing 2 high-temperature flue gas 1 is then switched to enter the first-stage adsorption reactor 1# and the second-stage adsorption reactor 2#, the control valves 8 and 12 are closed, and 10 and 13 are opened, and the reducing gas is switched to enter the conversion reactor to repeat the above operation.

[0058] As shown in the appendix Figure 2 shown, there are a 1# conversion electric heater 15 and a 2# conversion electric heater 16. The method steps are different from those in the appendix Figure 1 in that during the conversion reaction, external supplementary heat can be obtained through the conversion reactor 15 or 16 to meet the temperature requirements of the next-stage conversion reaction. The further steps are as follows: the process gas from the heat exchanger 6 is heated up after being supplemented with heat by the 2# conversion electric heater 16 and then enters the second-stage conversion reactor 4# to continue the conversion and regeneration; after the adsorption and conversion functions are exchanged, the 1# conversion electric heater 15 is used as the external supplementary heat heat source.

[0059] The 1# conversion electric heater 15 and the 2# conversion electric heater 16 can share one unit and can be switched by crossing lines with each other.

[0060] The four reactors exchange feeds, and there may be steps such as purging before switching in the middle. The present invention will not elaborate on them one by one.

[0061] The present invention will be further described below in conjunction with specific embodiments. The specific embodiments should not be regarded as limiting the protection scope of the present invention.

[0062] Embodiment:

[0063] Taking the high-temperature flue gas of 6700 m 3 n / h of raw materials as an example, the flue gas composition is as follows:

[0064] Flue gas composition v％ <![CDATA[CO 2 > 35 <![CDATA[H 2 O]]> 6.0 <![CDATA[N 2 > 56.5 <![CDATA[O 2 > 2.5

[0065] The flue gas temperature is 676 °C and the flue gas pressure is 12 kPa. The adsorption reactors 1# and 2# and the conversion reactors 3# and 4# are switched. When the adsorption reactors 1# and 2# are in the adsorption state, the conversion reactors 3# and 4# are in the conversion and regeneration state.

[0066] 1) Control valves 7 and 11 are opened, and the 676 °C high-temperature flue gas 1 enters the first-stage adsorption reactor 1# from the lower part.

[0067] 2) In the adsorption reactors 1# and 2#, the catalyst bed 2 of the CaO-based catalytic material and the Al 2 O 3 spherical heat storage body, the catalytic material is loaded with Co active component, which is used to catalyze the reaction of CO 2 with H 2 .

[0068] 3) According to the calculation, according to the 2.5-hour switching cycle, 0.82 m of catalytic material needs to be filled in each reactor 3 . The reaction heat release load during the adsorption process is 3.96 MW. Considering the changes in the composition and amount of the inlet and outlet gases, the total heat storage load required in the reactor is 4.81 MW. To control the reactor temperature not to exceed 750 °C (1023 K), for different ratios of catalytic materials, it is calculated that when the ratio of catalytic materials in the reactor is 33%, that is, when the heat storage body: catalytic material is 2:1, the final temperature of the decarbonized flue gas at the reactor outlet is 710 °C, meeting the requirements.

[0069] 4) Control valves 7 and 11 are opened, and the flue gas enters the first-stage adsorption reactor 3# through control valve 7, and the high-temperature CO2 gas passes through the catalyst bed 5. In the catalyst bed, CaO in the catalytic adsorption material reacts with CO 2 to generate CaCO 3 , and the released heat raises the temperature of the flue gas and the bed. After heat exchange and cooling with the syngas from the first-stage conversion reactor 3# through the heat exchanger 6, and further adsorbed by the second-stage adsorption reactor 2#, the purified flue gas temperature is 710 °C, and the purified flue gas volume is 2728.7 m 3 n / h, which is discharged from the top of the second-stage adsorption reactor 2# and sent to the chimney for emission after heat recovery. At this time, the 1# conversion reaction heater 15 is in the closed state.

[0070] 5) Meanwhile, control valves 10 and 13 are opened. In the other two reforming reactors #3 and #4, CaCO in the catalytic adsorption material 3 reacts with the excessive H at 730 °C introduced 2 to generate CaO, CO, and water. Most of the heat required is provided by the heat stored in the regenerator during the adsorption process. At the same time, it is heated up by exchanging heat with the high-temperature flue gas from the first-stage adsorption reactor #1 through heat exchanger 6. The insufficient part is provided by the #2 reforming heat exchanger 16.

[0071] 6) The flow rate of the reaction product syngas is 5623.8 m 3 n / h, and the temperature of the syngas is 500 °C. It is discharged from the gas outlet of the second-stage reforming reactor #4. The expected composition of the syngas is as follows:

[0072]

[0073]

[0074] 7) After 2 hours, after the reactor is purged with hot nitrogen, control valves 7, 10, 11, and 13 are closed, and 8, 9, 12, and 14 are opened, and the flue gas and hydrogen feeds are switched. Then, it is cycled sequentially according to the time sequence control.

[0075] The flue gas treated by this embodiment can achieve a reduction in CO 2 emissions of 35,000 t / a, and at the same time, 29,000 t / a of by-product syngas is produced.

Claims

1. A multi-stage carbon dioxide capture and utilization method, characterized in that The method comprises the following steps: 1) High-temperature flue gas containing CO2 enters the adsorption reactor and passes through the adsorption reactor equipped with a bifunctional catalyst. The CO2 in the flue gas is adsorbed and captured by the catalytic material in the catalyst bed, and the heat generated during the adsorption reaction is absorbed by the heat storage body in the catalyst bed; 2) After the decarbonization in step 1), the gas comes out of the adsorption reactor, exchanges heat with the process gas from the conversion reactor in a heat exchanger, and enters the next-stage adsorption reactor after the heat exchange, wherein the CO2 is further adsorbed and captured by the catalytic material in the catalyst bed, and the heat generated during the adsorption reaction is absorbed by the heat storage body in the catalyst bed. The gas that meets the decarbonization standard comes out of the adsorption reactor and is discharged after the waste heat is recovered; 3) When the adsorption reactor reaches the saturated adsorption capacity of the adsorbent, the high-temperature flue gas containing CO2 switches to enter the first-stage conversion reactor. At this time, the reducing gas enters the adsorption reactor, passes through the catalyst bed of the adsorption reactor, and the catalytic material adsorbing CO2 reacts with the reducing gas, and the carbon dioxide is reduced to CO. The heat required for the conversion reaction is provided by the heat storage body after the heat absorption in step 1) and the gas after decarbonization after the first-stage adsorption reaction through the heat exchanger; the process gas enters the next-stage conversion reactor for further conversion, and the synthesis gas after the conversion is completed is sent out of the device; 4) When the conversion reactor reaches the expected saturated adsorption capacity of the adsorbent, the conversion reactor and the adsorption reactor are functionally interchanged through feed switching, the high-temperature flue gas containing CO2 is switched to enter the adsorption reactor, and the reducing gas is switched to enter the conversion reactor, and the above steps are repeated.

2. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The process gas mentioned in steps 2) and 3) refers to the reducing gas contained in the conversion reactor for generating synthesis gas.

3. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The catalyst beds of the adsorption reactor and the conversion reactor are both filled with catalytic materials and heat storage bodies. The catalytic materials refer to materials having dual functions of carbon dioxide adsorption and catalytic conversion, and the heat storage bodies refer to materials having heat storage functions.

4. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The reducing gas refers to one or a mixture of more than one gas that can react with CO2 to generate CO, or a mixture of these gases and an inert gas.

5. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: Step 2) The adsorption reaction temperature is between room temperature and 800°C, and the conversion reaction temperature is between 100°C and 950°C.

6. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: In step 3), the catalytic material adsorbed with CO2 reacts with the reducing gas, and the carbon dioxide is reduced to CO. At this time, the temperature of the catalyst bed and the gas decreases. After the reducing gas containing synthesis gas in the first-stage conversion reactor exchanges heat with the high-temperature CO2 gas in step 1), the temperature rises. The insufficient heat can be supplemented by a heater or other external heat source.

7. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The adsorption reactor and the conversion reactor are both fixed bed reactors. Multiple layers of catalyst beds are arranged in a single reactor, and each layer is separated by a partition.

8. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: A plurality of reactors may also be provided, with one or more catalyst beds being provided in each reactor.

9. A multi-stage carbon dioxide capture and utilization device, mainly comprising an adsorption reactor, a conversion reactor and a heat exchanger, characterized in that: Catalytic materials and heat storage bodies are simultaneously loaded in the catalyst beds of the adsorption reactor and the conversion reactor. The adsorption reactor is a two-stage adsorption reactor, and the conversion reactor is also a two-stage conversion reactor. During the adsorption reaction process, the first-stage adsorption reactor is connected to high-temperature CO2 flue gas at the top and a heat exchanger at the bottom; the second-stage adsorption reactor is connected to purified flue gas at the bottom; during the conversion and regeneration process, the first-stage conversion reactor is connected to reducing gas at the top and a heat exchanger at the bottom; the second-stage conversion reactor is connected to synthesis gas at the bottom.

10. The carbon dioxide capture and utilization device according to claim 9, characterized in that: An external supplementary heat heater is also provided, and the external supplementary heat heater is respectively connected to the second-stage conversion reactor and the heat exchanger.

11. The carbon dioxide capture and utilization device according to claim 9, characterized in that: The adsorption reactor and the conversion reactor are both fixed bed reactors, and are arranged in single or multiple units.

12. The carbon dioxide capture and utilization device according to claim 9, characterized in that: The catalytic material refers to a material having the dual functions of carbon dioxide adsorption and catalytic conversion; the heat storage body refers to a material having a heat storage function.

13. The carbon dioxide capture and utilization device according to claim 9, characterized in that: The adsorption reactor and the conversion reactor are of the following types: inlet from bottom to top, inlet from top to bottom, inlet from side to side, inlet from the periphery and outlet from the middle, or inlet from the middle and outlet from the periphery.

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