Flexible and efficient carbon dioxide high-temperature capture and in-situ conversion device and method

Abstract

According to the flexible and efficient carbon dioxide high-temperature capture and in-situ conversion device and method, carbon dioxide high-temperature capture is conducted on industrial flue gas, and the industrial flue gas is converted into synthesis gas in an in-situ recycling mode. According to the method, carbon dioxide adsorption and conversion are completed in situ under the approximate temperature and pressure conditions, the energy utilization rate can be fully increased, the emission reduction cost can be effectively reduced, high energy consumption caused by capture cooling / conversion heating can be avoided, and the high cost of purification and transportation after CO2 capture and potential safety hazards caused by burying are avoided; the reactor disclosed by the invention is intrinsically safe, and the possibility of overtemperature and damage of the reactor and a catalytic material caused by non-uniform reaction, accidental interruption of a heat exchange medium and the like of a traditional reactor can be avoided; the reactor is low in pressure drop, simple in process, easy to operate and maintain, low in investment and small in occupied area; in-situ coupling utilization of heat in the adsorption heat release / conversion heat absorption process can be achieved, and energy is saved by 50% or above compared with an existing reactor.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon capture and utilization, and specifically relates to a flexible and efficient high-temperature capture and in-situ conversion device and method for carbon dioxide. Background Art

[0002] Carbon capture, utilization and storage (CCUS) is the most important technical path to address global climate change and control greenhouse gas emissions. 2 There are many sources of CO emissions, such as cement, steel, electricity, coal chemical industry and refineries. 2 Major emitters of CO 2 Emissions issues, all industries have carried out CO 2 Each industry has formed a variety of CO2 capture, utilization and storage according to its own characteristics. 2 Technological approaches to capture, utilization and storage.

[0003] At present, 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 solvent cost is high and the regeneration energy consumption is high, resulting in an additional increase of about 30% in the energy consumption of coal-fired power plants. At the same time, the captured CO 2 Offsite storage requires high transportation costs and is also subject to questionable safety issues. Adsorption is also relatively mature in technology, but is generally only used in 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 that deserve attention. 2 The key is the technology to capture and convert it into high value-added chemicals.

[0004] In recent years, 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 details of major domestic industrial pilot and demonstration projects are as follows: The CO2-based power plant launched by Huaneng Group at Shanghai Shidongkou Second Power Plant in December 2009 2 The capture demonstration project used a CO 2 Capture technology, CO captured annually 2The scale reaches 120,000 tons, capturing CO 2 The purity reaches over 99.5%. The captured CO 2 Some 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 The 250MW IGCC unit of Huaneng Tianjin Green Coal Power was completed and put into operation in 2011, and the 400MW unit with CO 2 The IGCC unit with capture device is designed to research, develop, demonstrate and promote CO 2 The near-zero-emission coal-based power generation system can significantly improve power generation efficiency and master the design, construction and operation technologies of large-scale coal gasification projects.

[0005] Three companies have established calcium cycle CO capture technology. 2 The pilot demonstration included the flue gas CO 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 at ITRI Research Institute, Taiwan, China 2 The capture pilot adopts the calcium circulation double fluidized bed circulation capture system to achieve CO in flue gas 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. 2 Most of the research on capture and conversion focuses 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 process design and reactor type 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. On the one hand, the coils are used for heat extraction / supplementation. As the capture / conversion process switches, the coils absorb heat and extract heat at times, which makes control difficult. On the other hand, due to the uneven reaction in the catalyst bed, it is difficult to avoid local overheating / undercooling. Direct combustion heating often causes the problem of overheating of the gas after combustion. Taking the commonly used CaO / CaCO 3 For example, when the temperature is > 850-900°C, the adsorbent will melt and sinter, while CO 2The conversion process generally requires a reaction temperature of 500-700℃ or above. If direct combustion is used to supplement heat, the temperature is too high and the adsorbent will melt, sinter and become inactive. If the temperature is controlled to less than 800℃, the heat supplement is very limited due to the temperature difference, or too much fuel gas and combustion-supporting gas need to be supplemented, resulting in severe dilution of the product and a decrease in the effective gas concentration. If the reactor adopts a fluidized bed, moving bed or other types, since most industrial flue gas is at normal pressure or low pressure, it is basically impossible to achieve this by conventional means due to pressure limitations.

[0007] CN202011629677.3 discloses a method and a reactor for in-situ conversion of carbon dioxide in flue gas output from a power plant, which utilizes the heat of high-temperature flue gas to heat carbonate and form a molten carbonate slurry bed. At the same time, coal powder is added to the reactor to form coke and volatile gases at high temperature. Coke and carbon dioxide form coal gas under the catalysis of molten carbonate, and volatile gases react with carbon dioxide to generate synthesis gas. In this reaction, the reaction of coal powder and carbon dioxide is an endothermic reaction, and the conversion of carbon dioxide into synthesis gas is also an endothermic reaction. Taking the reaction of carbon dioxide and methane as an example, the reaction of carbon dioxide and methane in an equivalent ratio requires 337kW of heat absorption. If only the heat in the input high-temperature flue gas is relied on, the reaction cannot be maintained for long-term operation. And the reactor is similar to a moving bed, and the pressure drop is too large. Usually, the flue gas pressure is low, and the pressure drop is too large to limit the application of this technology.

[0008] CN201821322948.9 discloses a catalytic reaction device, which is a two-stage reactor equipped with different catalysts. The upper stage is equipped with a catalyst for the reaction of carbon dioxide and hydrogen, and the lower stage is equipped with a catalyst for the reaction of methane, oxygen and water vapor. After carbon dioxide enters the upper reaction section, it reacts with hydrogen to generate carbon monoxide, and carbon monoxide is discharged from the top. Carbon dioxide hydrogenation is a strong endothermic reaction. The reaction of carbon dioxide and hydrogen in an equivalent ratio will cause a temperature drop of 150°C for every 5% reaction. The reaction process of this device cannot be continued without continuous heat input. In addition, the device does not involve the capture of carbon dioxide from industrial high-temperature flue gas, but only integrates the reactors for the hydrogenation reaction of carbon dioxide and the reaction of methane, oxygen and water vapor.

[0009] CN202010200151.7 discloses a reduction furnace system, which uses carbon dioxide and blue charcoal as reaction objects in the process of reducing carbon dioxide, and carbon dioxide and blue charcoal generate carbon monoxide under high temperature conditions. First, the process of reducing carbon dioxide to carbon monoxide is a strong endothermic reaction. If there is no continuous heat supplement, the reaction cannot be self-sustaining; secondly, industrial flue gas contains impurities other than carbon dioxide, which react with blue charcoal, water vapor, and oxygen to easily form phenolic substances and tar, so the reduction furnace system cannot be used for the capture of carbon dioxide in industrial flue gas; finally, the reduction furnace system is similar to a fluidized bed, and industrial flue gas is usually atmospheric pressure or slightly positive pressure gas. The pressure drop of the fluidized bed is too large, and the reaction cannot proceed.

[0010] At present, the patents and documents published at home and abroad are concentrated in CO 2 Capture and high purity CO 2 In terms of resource utilization research, for CO in industrial high-temperature flue gas 2 There is little research on the capture and in-situ resource conversion of CO in industrial high-temperature flue gas. 2 Efficiently capture and capture CO 2 In-situ resource conversion into synthesis gas products is convenient for the subsequent synthesis of light hydrocarbons and other chemical products with high added value. On the one hand, it can improve energy utilization and reduce carbon emissions. On the other hand, it can avoid the high energy consumption caused by frequent cooling / heating in the capture process. 2 In-situ resource conversion also solves the problem of CO 2 The high cost of purification and transportation after capture, as well as the safety risks caused by storage, have put great pressure on the overall CO 2 The feasibility and economy of the emission reduction process are of great significance. Summary of the invention

[0011] In view of the deficiencies of the above-mentioned background technology, the present invention provides a flexible and efficient high-temperature capture and in-situ conversion device and method of carbon dioxide, which captures carbon dioxide from industrial high-temperature flue gas and converts it into synthesis gas in situ.

[0012] The technical solution of the present invention is as follows:

[0013] A flexible and efficient high-temperature carbon dioxide capture and in-situ conversion device comprises a first reactor, a second reactor, a heating tube, a first heat-conducting salt pump, a second heat-conducting salt pump, a first electric heater and a second electric heater; a catalytic material bed is arranged in the first reactor and the second reactor; one side of the heating tube passes through the catalytic material bed of the first reactor and is respectively connected to the first heat-conducting salt pump and the second electric heater, and the other side of the heating tube passes through the catalytic material bed of the second reactor and is respectively connected to the first electric heater and the second heat-conducting salt pump; the first heat-conducting salt pump is connected to the first electric heater, and the second heat-conducting salt pump is connected to the second electric heater.

[0014] The present invention provides a flexible and efficient high-temperature capture and in-situ conversion device for carbon dioxide, which is further characterized in that the first reactor and the second reactor are of the type of bottom-in and top-out, top-in and bottom-out, side-in and side-out, periphery-in and middle-out, middle-in and periphery-out, etc.

[0015] The present invention provides a flexible and efficient carbon dioxide capture and in-situ conversion device, which is further characterized in that an air inlet distributor is arranged in the first reactor and the second reactor.

[0016] The present invention provides a flexible and efficient method for high-temperature capture and in-situ conversion of carbon dioxide, using the flexible and efficient high-temperature capture and in-situ conversion device of carbon dioxide, comprising the following steps:

[0017] 1) The carbon dioxide-containing gas enters the first reactor, and an adsorption reaction occurs in the reactor bed. The carbon dioxide in the gas is adsorbed and captured by the catalytic material. The heat released by the adsorption reaction is absorbed by the molten heat-conducting salt in the heating tube in the bed, and the bed and gas temperatures rise. Decarbonized gas is produced at the top of the first reactor;

[0018] 2) At the same time, the reducing gas enters the second reactor, and the reducing gas undergoes a conversion and regeneration reaction with the catalytic material adsorbing saturated carbon dioxide in the bed of the second reactor, the catalytic material is regenerated, and product synthesis gas is generated at the top of the second reactor; the heat required for the reaction is pumped into the second reactor by the molten heat-conducting salt in the heating tube through the first heat-conducting salt pump, and the insufficient heat is supplemented by the first electric heater;

[0019] 3) When the first reaction achieves the expected adsorption effect, the two reactors exchange feeds, the first reactor performs a conversion and regeneration reaction, and the second reactor undergoes an adsorption reaction. The heat required for the reaction in the first reactor is pumped into the first reactor by the molten heat-conducting salt in the heating tube through the second heat-conducting salt pump, and the insufficient heat is supplemented by the second electric heater; after exchanging feeds, product synthesis gas is generated at the top of the first reactor, and decarbonized gas is generated at the top of the second reactor;

[0020] 4) Repeat steps 1) to 3) to carry out the reaction in a cycle.

[0021] The present invention provides a flexible and efficient high-temperature carbon dioxide capture and in-situ conversion device method, which is further characterized in that the reactor is purged with a high-temperature inert gas before exchanging the feed.

[0022] The present invention provides a flexible and efficient high-temperature carbon dioxide capture and in-situ conversion device method, which is further characterized in that there can be multiple reactors, some of which are in an adsorption reaction state and some of which are in a conversion regeneration state.

[0023] The present invention provides a flexible and efficient high-temperature carbon dioxide capture and in-situ conversion device method, which is further characterized in that when multiple reactors are used, the feed can be switched by switching multiple reactors simultaneously or by switching each reactor independently to reduce the impact of fluctuations on upstream gases.

[0024] The present invention provides a flexible and efficient high-temperature capture and in-situ conversion method for carbon dioxide, which is further characterized in that the molten heat-conducting salt is converted into a molten state at above 400°C.

[0025] The expected adsorption effect (saturated adsorption capacity of the adsorbent) described in the present invention can be controlled by timing according to the designed switching time; it can also be controlled online according to the carbon dioxide content of the gas after decarbonization; other control methods can also be used.

[0026] The reducing gas of the present invention refers to a gas that can be 2 Gases that react to form synthesis gas, such as H 2 , CH 4 , C 2 H 6 etc., or a mixture of one or more of these gases, or a mixture of these gases and an inert gas (such as nitrogen). When these gases are introduced separately, the following reactions will occur:

[0027] CO 2 +2H 2 =CO+H 2 O+H 2

[0028] or CO 2 +H 2 =CO+H 2 O

[0029] CO 2 +CH 4 =2CO+2H 2

[0030] 2CO 2 +C 2 H 6 =4CO+3H 2

[0031] The catalytic material described in the present invention refers to solid particles with dual functions of carbon dioxide adsorption and catalytic conversion, such as CaO materials loaded with active ingredients such as Co, Ni, and lanthanide metals; the molten thermal conductive salt described in the present invention refers to salt materials with heat storage and thermal conductivity functions, which are in a molten state at the reaction temperature, such as nitrates and carbonates.

[0032] Step 1) The heating tubes are evenly distributed in the middle of the catalytic material, and the heating tubes are arranged at a certain distance. The more heating tubes there are and the more evenly they are arranged, the lower the bed temperature rise will be, but the bed effective space utilization rate will also be lower, and vice versa. Catalytic material amount A (m 3 ) is determined by the amount of carbon dioxide to be adsorbed A1 (t / h), the material adsorption capacity A2 (t / m 3 ) and the design switching time A3(h), the specific calculation formula is as follows:

[0033] A=A1xA3 / A2

[0034] The amount of heat-conducting salt is determined by the inlet temperature of the carbon dioxide-containing gas, the gas composition and specific heat, the exothermic heat of the adsorbed carbon dioxide reaction, the amount and specific heat of the catalytic material, the specific heat of the heat-conducting salt, the reactor heat loss, and the final reactor bed temperature that is desired to be controlled.

[0035] The beneficial effects of the present invention are as follows:

[0036] 1. Carbon dioxide adsorption and conversion are completed in situ under similar temperature and pressure conditions, which can not only fully improve energy utilization and effectively reduce emission reduction costs, but also avoid the high energy consumption of capture cooling / conversion heating, solving the problem of CO 2 The high cost of purification and transportation after capture, as well as the safety risks caused by burial;

[0037] 2. The reactor is inherently safe, which can avoid the possibility of overheating and damage of the reactor and catalytic materials caused by uneven reaction and accidental interruption of heat exchange medium in traditional reactors;

[0038] 3. It can realize the in-situ coupled utilization of heat in the adsorption exothermic / conversion endothermic process, saving more than 50% energy compared with existing reactors;

[0039] 4. The reactor has low pressure drop and can be applied to most industrial flue gas conditions;

[0040] 5. Simple process, easy to operate and maintain, low investment and small footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0042] In the figure: 1. Carbon dioxide-containing gas; 2. Reducing gas; 3. Decarbonized gas; 4. Product synthesis gas; 5. First reactor; 6. Second reactor; 7. Reactor bed; 8. Heating tube; 9. Reactor gas inlet; 10. Air inlet distributor; 11. Reactor gas outlet; 12. First thermal salt pump; 13. First electric heater; 14. Second thermal salt pump; 15. Second electric heater. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with specific examples. The examples are only implementation methods of the present invention under certain specific conditions and should not be regarded as limiting the protection content of the present invention.

[0044] Example:

[0045] like Figure 1 As shown: 409m2 of carbon dioxide-containing gas raw material 3 Take n / h as an example, the specific composition is as follows:

[0046]

[0047]

[0048] The carbon dioxide-containing gas 1 at 678°C and 10 kPa enters the first reactor 5 through the first reactor gas inlet 9, is evenly distributed in the first reactor cross section through the gas inlet distributor 10, and passes through the reactor bed 7. The reactor bed 7 is filled with a CaO-based catalytic material, on which a Co active center is loaded, for catalyzing CO 2 With H 2 The reaction of CaO and CO in the bed 2 The reaction produces CaCO 3 The released heat increases the temperature of the decarburized gas 3 and the heat-conducting salt in the heating tube 8. The decarburized gas 3 is discharged from the gas outlet 11 of the first reactor at a temperature of 727°C and a gas volume of 351m 3 n / h, and then discharged into the chimney after heat recovery.

[0049] The carbon dioxide-containing gas 1 enters the first reactor 5 from bottom to top, and the heat accumulates upward along the first reactor 5. The gas temperature at the gas outlet 11 of the first reactor is the highest, and the heat-conducting salt needs to absorb more heat to prevent CaCO 3 Sintering, so the heat-conducting salt flows through the first reactor from top to bottom, and the carbon dioxide-containing gas and the heat-conducting salt perform countercurrent heat exchange.

[0050] Excess hydrogen at 730°C enters the second reactor 6 as reducing gas 2 and reacts with the saturated catalytic material, CaCO 3 Reacts with hydrogen to produce CaO, CO, H 2 and water, the product synthesis gas produced by the reaction is 255m 3 n / h, temperature 630°C, the expected composition of the product synthesis gas 4 is as follows:

[0051] Element ％v CO 30.77 <![CDATA[H 2 ]]> 30.77 <![CDATA[CO 2 ]]> 7.69 <![CDATA[H 2 The]]> 30.77 total 100

[0052] After two hours, the reaction achieved the expected adsorption effect. After the reactor was purged with hot nitrogen, the feed of carbon dioxide-containing gas 1 and reducing gas 2 was switched, and the outlet valves were switched at the same time. The first reactor underwent a conversion and regeneration reaction, and the second reactor underwent an adsorption reaction. The cycles were then circulated in sequence according to timing control.

[0053] The molten heat-conducting salt absorbs heat in the first reactor 5 and its temperature rises. It then passes through the first heat-conducting salt pump 12 and the first electric heater 13 to supplement the heat lacking in the conversion and regeneration reaction, and then is sent to the second reactor 6. The reaction between the reducing gas and the saturated catalytic material is an endothermic reaction, which absorbs the heat in the molten heat-conducting salt. After the molten heat-conducting salt releases heat, it passes through the second heat-conducting salt pump 14 and the second electric heater 15 to supplement the lack of heat, and then is sent back to the first reactor 5 to achieve heat circulation.

[0054] According to calculations, each reactor needs to be filled with 3.85m3 of catalytic material based on a two-hour switching cycle. 3 The exothermic load of the adsorption process is about 128kW, and the endothermic load is 156kW. Considering the energy difference between the inlet and outlet gases and the heat loss of the reactor, the total required heat supplement load is 250kW. After deducting the heat accumulated by the thermal salt, electric heating is required according to the total load of 94kW. In this process, in order to enable the conversion process to proceed, the temperature in the reactor needs to be kept at no less than 630℃; in order to ensure that the catalytic material is not damaged, the maximum temperature of the gas needs to be controlled not to exceed 750℃.

[0055] After treatment in this embodiment, CO 2 Emissions were reduced by 1,373 t / a, while 1,734 t / a of synthesis gas was produced as a by-product.

Claims

1. A flexible and efficient high-temperature capture and in-situ conversion device for carbon dioxide, characterized by: It includes a first reactor, a second reactor, a heating tube, a first thermal salt pump, a second thermal salt pump, a first electric heater and a second electric heater; a catalytic material bed is arranged in the first reactor and the second reactor; one side of the heating tube passes through the catalytic material bed of the first reactor and is respectively connected to the first thermal salt pump and the second electric heater, and the other side of the heating tube passes through the catalytic material bed of the second reactor and is respectively connected to the first electric heater and the second thermal salt pump; the first thermal salt pump is connected to the first electric heater, and the second thermal salt pump is connected to the second electric heater.

2. A flexible and efficient high-temperature capture and in-situ conversion device for carbon dioxide according to claim 1, characterized in that: The first reactor and the second reactor are of the type of bottom-in and top-out, top-in and bottom-out, side-in and side-out, periphery-in and middle-out, middle-in and periphery-out, etc.

3. A flexible and efficient high-temperature capture and in-situ conversion device for carbon dioxide according to claim 1, characterized in that: The first reactor and the second reactor are both provided with an air inlet distributor.

4. A flexible and efficient high-temperature capture and in-situ conversion method of carbon dioxide, using the flexible and efficient high-temperature capture and in-situ conversion device of carbon dioxide according to claim 1, characterized in that The following steps are involved: 1) The carbon dioxide-containing gas enters the first reactor, and an adsorption reaction occurs in the reactor bed. The carbon dioxide in the gas is adsorbed and captured by the catalytic material. The heat released by the adsorption reaction is absorbed by the molten heat-conducting salt in the heating tube in the bed, and the bed and gas temperatures rise. Decarbonized gas is produced at the top of the first reactor; 2) At the same time, the reducing gas enters the second reactor, and the reducing gas undergoes a conversion and regeneration reaction with the catalytic material adsorbing saturated carbon dioxide in the bed of the second reactor, the catalytic material is regenerated, and product synthesis gas is generated at the top of the second reactor; the heat required for the reaction is pumped into the second reactor by the molten heat-conducting salt in the heating tube through the first heat-conducting salt pump, and the insufficient heat is supplemented by the first electric heater; 3) When the first reaction achieves the expected adsorption effect, the two reactors exchange feeds, the first reactor performs a conversion and regeneration reaction, and the second reactor undergoes an adsorption reaction. The heat required for the reaction in the first reactor is pumped into the first reactor by the molten heat-conducting salt in the heating tube through the second heat-conducting salt pump, and the insufficient heat is supplemented by the second electric heater; after exchanging feeds, product synthesis gas is generated at the top of the first reactor, and decarbonized gas is generated at the top of the second reactor; 4) Repeat steps 1) to 3) to carry out the reaction in a cycle.

5. A flexible and efficient high-temperature capture and in-situ conversion method for carbon dioxide according to claim 4, characterized in that: The reactor is purged with a high temperature inert gas before exchanging the feed.

6. A flexible and efficient high-temperature capture and in-situ conversion method of carbon dioxide according to claim 4, characterized in that: There may be multiple reactors, some of which are in the adsorption reaction state, and some of which are in the conversion and regeneration state.

7. A flexible and efficient high-temperature capture and in-situ conversion method for carbon dioxide according to claim 6, characterized in that: When multiple reactors are used, the feed can be switched by switching multiple reactors simultaneously or by switching each reactor independently.

8. A flexible and efficient high-temperature capture and in-situ conversion method for carbon dioxide according to claim 4, characterized in that: The catalytic material in step 1) is a CaO material loaded with one or more active components of Co, Ni, and lanthanide metals.

9. A flexible and efficient high-temperature capture and in-situ conversion method of carbon dioxide according to claim 4, characterized in that: Step 2) The reducing gas is H2 or CH4 or C2H6; or a mixture of two or more thereof or a mixture of one or more thereof and an inert gas.

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