Method and device for recovering waste heat and capturing and utilizing carbon dioxide

Abstract

The invention discloses a waste heat recovery and carbon dioxide capture and utilization method and device, and the method comprises the following steps: 1) continuously carrying out an adsorption decarburization reaction on CO2-containing high-temperature flue gas from the outside under the action of a bifunctional catalyst, after decarburization is completed, discharging purified flue gas from the top of an adsorption reactor, and discharging the purified flue gas at high altitude; 2) when the adsorption reactor reaches the saturated adsorption capacity of the adsorbent, switching the CO2-containing high-temperature flue gas into a conversion reactor; and (3) when the conversion reactor reaches the expected saturated adsorption capacity of the adsorbent, the conversion reactor and the adsorption reactor realize function exchange through feeding switching, the CO2-containing high-temperature flue gas is switched to enter the adsorption reactor, the reducing gas is switched to enter the conversion reactor, and the operation is repeated. According to the invention, CO2 can be captured from high-temperature gas and converted into synthesis gas in situ.

Description

Technical Field

[0001] The present invention relates to a method for capturing carbon dioxide from high-temperature gas and in-situ converting it into syngas (hereafter and hereinafter, syngas refers to CO or a mixture of CO with hydrogen, water vapor, etc.), and particularly relates to a method and system for waste heat recovery and carbon dioxide capture and utilization. Background Art

[0002] Carbon capture, utilization, and storage (CCUS: Carbon Capture, Utilization and Storage) is the most important technical path to address global climate change and control greenhouse gas emissions. In modern industrial production, there are many emission sources of CO 2 , such as cement plants, steel mills, power plants, coal chemical industries, and refineries, etc., which are all major emitters of CO 2 . Regarding the CO 2 emission problem, various industries have conducted research and exploration on the capture, utilization, and storage of CO 2 . Each industry has formed various technical methods for the capture, utilization, and storage of CO 2 according to its own industry characteristics.

[0003] Currently, the focus of large-scale carbon capture research is concentrated in 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 needs to be heat-exchanged step by step to be absorbed at low temperature, and its high solvent cost and high regeneration energy consumption result in an additional energy consumption increase of about 30% in coal-fired power plants. At the same time, for the captured CO 2 stored in different locations, high transportation costs are required, and issues such as potential safety hazards are also highly questioned. The adsorption method is also relatively mature technically, but it is generally only used in working conditions with determined gas components. The capacity of the adsorbent and the CO 2 selectivity are relatively low, the cost is relatively high, and it is generally only used for low-temperature gases. The membrane method usually cannot achieve high-degree separation and requires multiple stages and / or recycling, resulting in an increase in complexity, energy consumption, and cost. At the same time, impurity components in the gas may also cause blockage. After capturing by these above methods, only high-concentration CO 2 gas is obtained, and subsequent transportation, utilization, etc. are also issues worthy of attention. Developing technologies for capturing CO 2 and converting it into high-value-added chemicals is the key.

[0004] In recent years, with the strong support of the Chinese government, enterprises, institutions, research units, and universities have jointly participated, and a series of research has been carried out on supporting policies, relevant theories, and key technologies, establishing a professional research team and achieving a number of results and progress. The specific situations of the main domestic industrial pilot and demonstration projects are as follows: The CO 2The capture demonstration project uses CO capture technology with independent intellectual property rights. 2 The annual CO capture scale reaches 120,000 tons, and the purity of the captured CO 2 reaches over 99.5%. A part of the captured CO 2 is used in the food processing industry after passing through the refining system, and the rest is used in industrial production. When the capture device was put into production, it was the world's largest flue gas CO capture device in a coal-fired power plant at that time. The 250MW-class IGCC unit of Huaneng Tianjin Green Coal Power was completed and put into production in 2011, and an IGCC unit with a capacity of 400MW and equipped with a CO 2 capture device was completed in 2016. The demonstration project aims to research, develop, and demonstrate the promotion of a near-zero-emission coal-based power generation system, which can significantly improve the power generation efficiency at the same time, and master the design, construction, and operation technologies of large-scale coal gasification projects. 2 At present, 3 enterprises have established pilot demonstrations for calcium-looping CO capture, including the 1.7MWth power plant flue gas CO 2 capture demonstration system of La Pereda Company in Spain, the 1MWth power plant flue gas CO 2 capture demonstration system of Darmstadt Company in Germany, and the 3kWth power plant flue gas CO

[0005] capture pilot test of the ITRI Research Institute in Taiwan, China. All of them adopt a calcium-looping dual-fluidized bed circulation capture system to achieve the capture and regeneration of CO in the flue gas. 2 capture demonstration system of the 1.7MWth power plant flue gas of La Pereda Company in Spain, the 1MWth power plant flue gas CO 2 capture demonstration system of Darmstadt Company in Germany, and the 3kWth power plant flue gas CO 2 capture pilot test of the ITRI Research Institute in Taiwan, China. All of them adopt a calcium-looping dual-fluidized bed circulation capture system to achieve the capture and regeneration of CO in the flue gas. 2 capture in the pilot test, all using a calcium-looping dual-fluidized bed circulation capture system to achieve the capture and regeneration of CO in the flue gas. 2

[0006] The above-mentioned technologies all focus on CO capture and do not involve conversion and subsequent utilization. The publicly disclosed patents on CO 2 capture and conversion mainly focus on catalysts. Since CO 2 capture is a strongly exothermic reaction and the conversion process is a strongly endothermic reaction, the temperature and heat control during the reaction process are extremely critical. The design of the process and the type of reactor are the keys to determining the feasibility of the technology. For strongly exothermic and endothermic reactions, the commonly adopted measures include: using coil heat extraction / supplementation, direct combustion heating, using fluidized beds, moving beds, etc. These methods all have some problems in CO 2 capture and conversion. When using coil heat extraction / supplementation, on the one hand, with the switching of the capture / conversion process, the coil absorbs heat for a while and extracts heat for a while, making it difficult to control; on the other hand, due to the uneven reaction in the catalyst bed, it is difficult to avoid local overheating / overcooling. When using the direct combustion heating method, there is often a problem of local overheating in the catalyst bed. Taking the commonly used CaO / CaCO 2 as an example 3 ​Taking a certain type of adsorbent as an example, when the temperature > 850 - 900 °C, the adsorbent will undergo melting and sintering, while for the CO 2 The CO conversion process generally requires a reaction temperature of 500 - 700 °C or higher. If direct afterburning heating is used, the temperature is too high, and the adsorbent will undergo melting and sintering and deactivate; if the temperature is controlled to be less than 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 beds or moving beds are used, since most industrial flue gases are at atmospheric pressure or low pressure, restricted by pressure, it is basically impossible to achieve with conventional means.

[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 on the granulated high-temperature heat carrier. The entire process has a long flow path, and the core equipment is similar to a fluidized bed, with a large pressure drop. The process temperature frequently changes between 50 °C and 1500 °C, and the drastic temperature change will inevitably bring about energy consumption problems; while the long flow path will also bring about 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. It is provided with a methane + steam reforming catalyst for hydrogen production at the lower part to generate 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 as follows: 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 actually cannot be self-sustaining and will soon terminate due to temperature reduction; second, this reactor does not involve carbon capture and is merely a carbon dioxide hydrogenation reactor.

[0009] Chinese Patent CN201410202280.4 discloses a method based on a manganese and lanthanide metal catalyst, which hydrogenates 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, 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 actually cannot be self-sustaining and will soon terminate due to temperature reduction; second, this reactor does not involve carbon capture and is merely a carbon dioxide hydrogenation reactor.

[0010] Currently, the patents, literature, etc. publicly available at home and abroad focus on CO 2 capture and the research on the reverse water gas shift reaction of CO 2 hydrogenation, while there is little research on the aspect of CO 2 capture and in-situ conversion. High-temperature CO 2 efficient capture, and the captured CO 2 is in-situ converted into syngas products, so as to facilitate the subsequent synthesis of high-value-added chemical products such as light olefins. This 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 / conversion heating, solve the high cost 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 purpose of the present invention is to provide a method and device for waste heat recovery and carbon dioxide capture and utilization in view of the deficiencies of the above-mentioned prior art, so as to capture CO 2 from high-temperature gas and in-situ convert it into syngas.

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

[0013] A method for waste heat recovery and carbon dioxide capture and utilization, characterized in that the method includes the following steps:

[0014] 1) The high-temperature flue gas containing CO 2 from the outside exchanges heat with the process gas from the conversion reactor in the flue gas-process gas heat exchanger, then recovers heat through the waste heat boiler, is boosted by the booster fan, exchanges heat and warms up with the flue gas from the adsorption reactor that has removed part of the CO 2 and then enters the adsorption reactor, passes through the adsorption reactor filled with the bifunctional catalyst, and the CO 2 in the flue gas is adsorbed and captured by the catalytic material in the catalyst bed. The heat generated during the adsorption process is absorbed and cooled by the CO 2 in the original flue gas through the interlayer heat exchanger of the adsorption layer, and then enters the next bed layer of the adsorption reactor, and continues the adsorption decarbonization reaction under the action of the bifunctional catalyst. After the decarbonization is completed, the purified flue gas comes out from the top of the adsorption reactor and is discharged into the air at a high altitude;

[0015] 2) When the adsorption reactor reaches the saturated adsorption capacity of the adsorbent, the high-temperature flue gas containing CO 2 is switched to enter the conversion reactor, and at this time its function is decarbonization adsorption, and the CO 2The high-temperature flue gas undergoes an adsorption and decarbonization process according to step 1); meanwhile, the reducing gas enters the adsorption reactor, passes through the first catalyst bed in the adsorption reactor, and the catalytic material that has adsorbed CO 2 reacts with the reducing gas. At this time, the temperature of the catalyst bed and the gas decreases. The reducing gas containing syngas coming out of the first catalyst bed of the autothermal reactor exchanges heat with the high-temperature CO 2 gas in the flue gas-process gas heat exchanger, and then the process gas enters the second catalyst bed of the autothermal reactor for further conversion. After the conversion is completed, the syngas is sent out of the device;

[0016] 3) When the autothermal reactor reaches the expected saturated adsorption capacity of the adsorbent, the functions of the autothermal reactor and the adsorption reactor are interchanged by switching the feeds. The high-temperature flue gas containing CO 2 is then switched to enter the adsorption reactor, and the reducing gas is switched to enter the autothermal reactor, and the above operations are repeated.

[0017] A method for waste heat recovery and carbon dioxide capture and utilization according to the present invention further comprises: in step 1), the adsorption reaction temperature is from room temperature to 800 °C, preferably in the range of 600 - 750 °C; the process gas herein refers to the reducing gas containing syngas in the autothermal reactor, and there are at least 2 autothermal reactors herein.

[0018] A method for waste heat recovery and carbon dioxide capture and utilization according to the present invention further comprises: in step 2), the autothermal reaction temperature is from 100 to 950 °C, preferably in the range of 600 - 800 °C; the process gas herein refers to the reducing gas containing syngas in the autothermal reactor.

[0019] A method for waste heat recovery and carbon dioxide capture and utilization according to the present invention further comprises: catalytic materials are filled in the catalyst beds of both the adsorption reactor and the autothermal reactor, and the catalytic materials refer to materials with dual functions of carbon dioxide adsorption and catalytic conversion.

[0020] A method for waste heat recovery and carbon dioxide capture and utilization according to the present invention further comprises: the reducing gas refers to a gas that reacts with CO 2 to generate CO, or a mixture of one or more of these gases, or a mixture of these gases and an inert gas (such as nitrogen).

[0021] A method for waste heat recovery and carbon dioxide capture and utilization according to the present invention further comprises: the high-temperature flue gas containing CO 2 refers to the flue gas containing CO 2 generated by various gas furnaces, oil furnaces or hydrogen production furnaces, etc.

[0022] The adsorption reactor and the conversion reactor in the present invention are the same, which is only for the convenience of description in the present invention. Both the adsorption reactor and the conversion reactor are fixed-bed reactors, which can be single or multiple units. The catalyst bed is filled with catalytic materials, which refer to materials with the dual functions of carbon dioxide adsorption and catalytic conversion, such as CaO materials loaded with one or more active components such as Co, Ni, and lanthanide metals. The catalyst bed is arranged in multiple layers, and should be at least 2 layers. The catalyst bed is arranged in multiple layers, and should be at least 2 layers. Multiple catalyst beds can be arranged in a single reactor, separated by partitions between each layer, or multiple reactors can be arranged, with 1 layer or multiple layers of catalyst beds arranged in each reactor.

[0023] The gas that can react with CO 2 to generate CO refers to H 2 , CH 4 or C 2 H 6 etc. When these gases are introduced separately, the following reactions will occur:

[0024] CO 2 +2H 2 =CO+H 2 O+H 2 or CO 2 +H 2 =CO+H 2 O

[0025] CO 2 +CH 4 =2CO+2H 2

[0026] 2CO 2 +C 2 H 6 =4CO+3H 2

[0027] The present invention also provides a waste heat recovery and carbon dioxide capture and utilization device to implement the above method.

[0028] A waste heat recovery and carbon dioxide capture and utilization device mainly includes a flue gas-process gas heat exchanger, a waste heat boiler, a booster fan, an adsorption reactor, and a conversion reactor, and is characterized in that: the hot side of the flue gas-process gas heat exchanger is connected to the waste heat boiler, the waste heat boiler is connected to the booster fan, the booster fan is connected to the adsorption reactor through an interlayer heat exchanger of the adsorption layer, and the cold side of the flue gas-process gas heat exchanger is connected to the first catalyst bed of the conversion reactor and the second catalyst bed of the conversion reactor.

[0029] A device for waste heat recovery and carbon dioxide capture and utilization according to the present invention is characterized in that the adsorption reactor and the conversion reactor are fixed bed reactors.

[0030] A device for waste heat recovery and carbon dioxide capture and utilization according to the present invention is characterized in that a catalyst bed layer and a partition plate are arranged in the adsorption reactor and the conversion reactor, and are divided into multiple catalyst bed layers by the partition plate. Multiple reactors can also be arranged, and one or more catalyst bed layers are arranged in each reactor. Catalytic materials are filled in the catalyst bed layers of the adsorption reactor and the conversion reactor, and the catalyst bed layers are arranged in multiple layers. The adsorption reactor and the conversion reactor can both be arranged with one or more reactors. When the adsorption reactor and the conversion reactor are arranged with multiple reactors, they can be switched simultaneously or independently one by one.

[0031] A device for waste heat recovery and carbon dioxide capture and utilization according to the present invention is characterized in that the interiors of the adsorption reactor and the conversion reactor are exactly the same and have dual functions. When one reactor is in the adsorption reaction, the other is in the conversion and regeneration state. After a specific time, the two reactors switch operations and their functions are interchanged.

[0032] A device for waste heat recovery and carbon dioxide capture and utilization according to the present invention is further characterized in that the flue gas-process gas heat exchanger is connected to the high-temperature flue of a gas furnace, an oil furnace, a hydrogen production furnace or other furnaces at the top and to a waste heat boiler at the bottom.

[0033] For the reactor of the present invention, the amount A (m 3 ) of the catalytic material is determined by the amount A1 (t / h) of carbon dioxide 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:

[0034] A = A1 × A3 / A2

[0035] Wherein: A1 represents the amount of carbon dioxide to be adsorbed;

[0036] A2 represents the material adsorption capacity;

[0037] A3 represents the designed switching time.

[0038] To achieve the expected adsorption conditions (saturated adsorption capacity of the adsorbent) in the present invention, timing control can be carried out according to the designed switching time; on-line control can be carried out according to the carbon dioxide content in the gas after decarbonization; or other control methods can also be adopted.

[0039] The present invention is applicable to the treatment of carbon dioxide-containing gases (such as high-temperature flue gas containing CO 2 ) to capture CO from the carbon dioxide-containing gas 2And in-situ convert it into syngas. The optimal temperature range for the use of this invention is room temperature to 800 °C.

[0040] The advantages of this invention compared with the prior art are as follows:

[0041] 1) In this invention, the carbon dioxide adsorption and conversion are completed in-situ under nearly the same temperature and pressure conditions, which can not only fully improve the energy utilization rate and effectively reduce the emission reduction cost, but also avoid the high energy consumption of capture cooling / transformation heating, solve the high costs of purification and transportation after CO 2 capture, as well as the potential safety hazards brought by storage;

[0042] 2) In the reactor of this 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;

[0043] 3) The heat in-situ coupling utilization of the adsorption exothermic / conversion endothermic process can be realized, and the energy consumption is saved by more than 50% compared with the existing reactors;

[0044] 4) The reactor has a low pressure drop and is applicable to most flue gas conditions;

[0045] 5) It is applicable to high-temperature CO 2 flue gas generated by various gas furnaces, oil furnaces or hydrogen production furnaces, etc., can realize the flue gas pressure boost, and the subsequent decarbonization is not affected by the pressure;

[0046] 6) The process is simple, easy to operate and maintain, with low investment and small floor area. Description of the Drawings

[0047] Figure 1 is a schematic diagram of a waste heat recovery and carbon dioxide capture and utilization device of this invention.

[0048] The reference numerals shown in the figure are: 1 - high-temperature carbon dioxide gas, 2 - reducing gas, 3 - decarbonized gas, 4 - product syngas, 5 - flue gas-process gas heat exchanger, 6 - waste heat boiler, 7 - booster fan, 8 - interlayer heat exchanger of the adsorption layer, 10 - partition board, 11 - adsorption reactor, 12 - conversion reactor, 111 - catalyst bed. Detailed Embodiments

[0049] As shown in the attached Figure 1As shown, a method and device for waste heat recovery and carbon dioxide capture and utilization. The number of reactors is 2, with 1 in the adsorption reaction state and 1 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 then 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. Since then, the adsorption reaction and the conversion reaction reach self-thermal equilibrium. For the convenience of description, the adsorption reactor and the conversion reactor are used to illustrate the present invention. The reactors of the present invention can also be multiple, with some reactors in the adsorption reaction state and some reactors 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 bed layers by means such as partitions.

[0050] For the convenience of description below, two reactors are taken as an example. As Figure 1 shown, there are two reactors, one is an adsorption reactor and the other is a conversion reactor. The steps of the waste heat recovery and carbon dioxide capture and utilization method are as follows:

[0051] 1) The high-temperature flue gas 1 containing CO from the upstream flue passes through the flue gas-process gas heat exchanger 5 to exchange heat with the syngas containing CO from the conversion reactor 12, then enters the waste heat boiler 5 to further recover heat, the temperature decreases, enters the booster fan 7 to boost the pressure, and the pressurized CO 2 flue gas enters the adsorption interlayer heat exchanger 8, absorbs the heat generated during the adsorption process and heats up, and then enters the catalyst bed layer of the adsorption reactor 11. The CO in the flue gas 2 is adsorbed and captured by the catalytic material in the catalyst bed layer 111. The adsorption reaction heat generated by the bed layer is supplied to the flue gas to heat up through the adsorption interlayer heat exchanger 8, and after cooling, it returns to enter the next catalyst bed layer. The decarbonized gas 3 comes out of the adsorption reactor 11. At this time, the adsorption reactor 11 is in the adsorption state, and a partition 10 is provided between the two adsorption bed layers. The adsorption reaction temperature is from normal temperature to 800 °C, preferably in the temperature range of 600-750 °C; 2

[0052] 2) After the conversion reactor 12 reaches the saturated adsorption capacity of the adsorbent in the previous cycle, the reducing gas 2 enters the first catalyst bed layer of the adsorption reactor 12. The catalytic material adsorbed with CO 2 reacts with the reducing gas, and carbon dioxide is reduced to CO. The temperature of the first bed layer of the reactor and the syngas containing CO decreases, and passes through the flue gas-process gas heat exchanger 5 to exchange heat with the high-temperature CO 2 ​After the flue gas is heated through heat exchange and then enters the second catalyst bed of the reforming reactor 12 to continue the reduction reaction. The syngas after the reduction reaction exits from the adsorption reactor 12. At this time, the adsorption reactor 12 is in the reforming state, and the reforming reaction temperature is 100-950°C, preferably in the range of 600-800°C;

[0053] 3) When the reforming reactor reaches the saturated adsorption capacity of the adsorbent, the reforming reactor and the adsorption reactor exchange functions, that is, the reforming reactor is used for the adsorption reaction, and the adsorption reactor is used for reforming. The high-temperature CO 2 gas and the reducing gas are switched to enter the reforming reactor or the adsorption reactor, and the above operations are repeated.

[0054] The two 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.

[0055] For the sake of simplicity of expression, Figure 1 only the situation where the adsorption reactor 11 is in the adsorption state and the reforming reactor 12 is in the reforming state is schematically shown. The valves and pipeline connections for the switching between the two are not drawn, and it should not be regarded as a limitation to the protected content of the present invention.

[0056] The present invention will be further described below in conjunction with specific embodiments. The embodiments are only the implementation methods of the present invention under a certain specific condition, and should not be regarded as a limitation to the protected content of the present invention.

[0057] Example 1:

[0058] Taking the high-temperature CO 2 flue gas of 330000 Nm 3 / h from the self-made hydrogen furnace as an example, the composition of the flue gas is as follows:

[0059] Flue gas composition v％ <![CDATA[CO 2 > 23.0 <![CDATA[H 2 O]]> 5.8 <![CDATA[N 2 > 65.0 <![CDATA[O 2 > 6.2

[0060] The flue gas temperature is 678°C, and the flue gas pressure is 10 kPa. The adsorption reactor 11 and the reforming reactor 12 are switched. When the adsorption reactor 11 is in the adsorption state, the reforming reactor 12 is in the reforming and regeneration state.

[0061] 1) The high-temperature CO 2 gas at 678°C from the self-made hydrogen furnace and the flue gas with part of CO2 removed from the reforming reactor 11 are heat-exchanged to 470°C through the flue gas-process gas heat exchanger 5, and then the waste heat is recovered by the waste heat boiler 6, and the temperature continues to drop to 250°C. After being boosted to 200 kPaG by the booster fan 7, it is heat-exchanged with the gas with part of carbon dioxide removed from the reforming reactor 11 through the reforming interlayer heat exchanger 8 and heated to 680°C and then enters the first catalyst bed of the adsorption reactor 11;

[0062] 2) High-temperature CO2 The gas undergoes an adsorption reaction in the reactor bed 111, where the CO 2 reacts with CaO in the bed to form CaCO 3 . The heat released raises the temperature of the flue gas and the bed. The heat release load during the adsorption process is 128.1 MW. After the heat is released from the adsorption reaction in the first bed of the adsorption reactor 11, the temperature of the flue gas reaches 727 °C. After being cooled to 680 °C through heat exchange in the conversion layer heat exchanger 8, it enters the conversion reactor 11 again and enters the second catalyst bed to continue the adsorption and removal of CO 2 , and the CO 2 -removed gas is discharged at high altitude after coming out of the adsorption reactor 11. The flue gas volume is 269000 Nm 3 / h;

[0063] 3) The adsorption reactor 11 and the conversion reactor 12 are filled with a CaO-based catalytic material 111, and the catalytic material is loaded with Co active centers for catalyzing the reaction of CO 2 with H 2 ;

[0064] 4) Meanwhile, in another conversion reactor 12, CaCO 3 undergoes a conversion reaction with the incoming reducing gas 2 to form CaO, CO, H 2 and water. The conversion reaction is carried out at 730 °C, and the endothermic load of the reaction is 154.9 MW. The required heat is obtained through heat exchange with the high-temperature carbon dioxide gas 1 in the flue gas-process gas heat exchanger 5, and no external heat supply is required.

[0065] 5) The reaction product synthesis gas volume is 182000 Nm 3 / h, and the synthesis gas temperature is 600 °C, which is discharged from the conversion reactor 12. The expected composition of the synthesis gas is as follows:

[0066] Component Composition CO 31.7v％ <![CDATA[H 2 > 35.0v％ <![CDATA[CO 2 > 1.7v％ <![CDATA[H 2 O]]> 31.6v％ Total 100v％

[0067] 6) After 2 hours, the reactor is purged with hot nitrogen, and then the feed of the high-temperature carbon dioxide gas and the reducing gas is switched, and the outlet valve is switched simultaneously. Then, it is cycled sequentially according to the time sequence.

[0068] The flue gas treated by this embodiment can achieve a reduction in CO 2 emissions by 1 million t / a, and at the same time, 1.091 million t / a of by-product synthesis gas is produced.

Claims

1. A method for waste heat recovery and carbon dioxide capture and utilization, characterized in that The method comprises the following steps: 1) After the high-temperature flue gas containing CO2 from the outside and the process gas from the reforming reactor are heat-exchanged in the flue gas-process gas heat exchanger, the heat is recovered by the waste heat boiler, the pressure is increased by the booster fan, and the flue gas from the adsorption reactor with some CO2 removed is heat-exchanged and heated up before entering the adsorption reactor. After passing 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. The heat generated during the adsorption process is absorbed and cooled by the original CO2 flue gas through the adsorption interlayer heat exchanger, and then enters the next bed of the adsorption reactor. The adsorption decarbonization reaction continues under the action of the bifunctional catalyst. After the decarbonization is completed, the purified flue gas comes out from the top of the adsorption reactor and is discharged into the air; 2) When the adsorption reactor reaches the saturated adsorption capacity of the adsorbent, the high-temperature flue gas containing CO2 switches to enter the conversion reactor, at which point its function is decarbonization adsorption, and the high-temperature flue gas containing CO2 undergoes an adsorption decarbonization process according to step 1); at the same time, the reducing gas enters the adsorption reactor, passes through the first catalyst bed in the adsorption reactor, and the catalytic material adsorbed with CO2 reacts with the reducing gas. At this time, the temperature of the catalyst bed and the gas decreases, and the reducing gas containing synthesis gas coming out of the first catalyst bed of the conversion reactor exchanges heat with the high-temperature CO2 gas in step 1) in the flue gas-process gas heat exchanger, and the process gas enters the second catalyst bed of the conversion reactor for further conversion, and the synthesis gas after the conversion is completed is sent out of the device; 3) 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 then switched into the adsorption reactor, and the reducing gas is switched into the conversion reactor, and the above operation is repeated.

2. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 1 is characterized in that: The adsorption reaction temperature in step 1) is room temperature to 800°C, and the conversion reaction temperature in step 2) is 100 to 950°C.

3. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 1 is characterized in that: The process gas refers to the reducing gas contained in the conversion reactor to generate synthesis gas.

4. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 1 is characterized in that: The catalyst beds of the adsorption reactor and the conversion reactor are both filled with catalytic materials, and the catalytic materials refer to materials with dual functions of carbon dioxide adsorption and catalytic conversion.

5. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 4 is characterized in that: The catalytic material refers to a CaO material loaded with one or more active components such as Co, Ni and lanthanide metals.

6. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 1 is characterized in that: The reducing gas refers to a gas that reacts with CO2 to generate CO, or a mixture of one or more of these gases, or a mixture of these gases and an inert gas (such as nitrogen).

7. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 1, characterized in that: The CO2-containing high-temperature flue gas refers to various CO2-containing flue gases produced by gas furnaces, oil furnaces or hydrogen production furnaces.

8. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 1, characterized in that: The adsorption reactor and the conversion reactor are both fixed bed reactors, which can be arranged in single or multiple units.

9. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 8, characterized in that: Multiple layers of catalyst beds are arranged in a single reactor, and each layer is separated by partitions.

10. The method for waste heat recovery and carbon dioxide capture and utilization according to claim 8, characterized in that: When multiple reactors are provided, one or more catalyst beds are provided in each reactor.

11. A waste heat recovery and carbon dioxide capture and utilization device, mainly comprising a flue gas-process gas heat exchanger, a waste heat boiler, a booster fan, an adsorption reactor and a conversion reactor, characterized in that: The hot side of the flue gas-process gas heat exchanger is connected to the waste heat boiler at the bottom, the waste heat boiler is connected to the booster fan at the bottom, the booster fan is connected to the adsorption reactor through the adsorption interlayer heat exchanger, and the cold side of the flue gas-process gas heat exchanger is connected to the first catalyst bed of the conversion reactor at the top and the second catalyst bed of the conversion reactor at the bottom.

12. The waste heat recovery and carbon dioxide capture and utilization device according to claim 11, characterized in that: The adsorption reactor and the conversion reactor are fixed bed reactors.

13. The waste heat recovery and carbon dioxide capture and utilization device according to claim 11, characterized in that: Catalyst beds and partitions are provided in the adsorption reactor and the conversion reactor, and the catalyst beds are divided into a plurality of catalyst beds by the partitions.

14. The waste heat recovery and carbon dioxide capture and utilization device according to claim 11, characterized in that: When multiple reactors are provided, one or more catalyst beds are provided in each reactor.

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