Device and method for high-temperature capture and in-situ conversion of gas-carrying-solid carbon dioxide

Abstract

The invention provides a gas-carrying-solid carbon dioxide high-temperature capture and in-situ conversion device and method, which are used for carrying out carbon dioxide high-temperature capture from industrial flue gas and converting the industrial flue gas into carbon monoxide or synthesis gas in an in-situ recycling manner. According to the method, carbon dioxide adsorption and conversion regeneration 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 is intrinsically safe, so that the possibility of reaction interruption caused by non-uniform reaction, accidental interruption of a heat exchange medium and the like of a traditional reactor can be avoided; the process is simple, easy to operate and maintain, low in investment and small in occupied area.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon capture and utilization, and specifically relates to a device and method for high-temperature capture and in-situ conversion of gas-carried solid 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. In response to the CO2 emission problem, various industries have conducted research and exploration on CO2 capture, utilization and storage. Each industry has developed a variety of CO2 capture, utilization and storage technical methods based on its own industry characteristics.

[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, which causes the energy consumption of coal-fired power plants to increase by about 30%. At the same time, the captured CO2 is stored off-site, which requires high transportation costs, and safety hazards are also questioned. The adsorption method is also relatively mature in technology, but it is generally only used for working conditions with a certain gas composition. The capacity and CO2 selectivity of the adsorbent are low, the cost is high, and it is generally only used for low-temperature gas. The membrane method usually cannot achieve a high degree of separation and requires 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 CO2 gas is obtained, and subsequent transportation and utilization are also issues worthy of attention. The development of CO2 capture and conversion technology 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, relevant 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 CO2 capture demonstration project launched by Huaneng Group in Shanghai Shidongkou Second Power Plant in December 2009 used CO2 capture technology with independent intellectual property rights, with an annual CO2 capture scale of 120,000 tons and a captured CO2 purity of more than 99.5%. Part of the captured CO2 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 operation, it was the largest flue gas CO2 capture device in the world for coal-fired power plants. The 250MW IGCC unit of Huaneng Tianjin Green Coal Power was completed and put into operation in 2011, and the 400MW IGCC unit equipped with a CO2 capture device was completed in 2016. The demonstration project aims to research, develop, demonstrate and promote a coal-based power generation system with near-zero CO2 emissions, while significantly improving power generation efficiency and mastering the design, construction and operation technologies of large-scale coal gasification projects.

[0005] Three companies in the world have established pilot demonstrations of calcium cycle CO2 capture, including Spain's La Pereda's 1.7MWth power plant flue gas CO2 capture demonstration system, Germany's Darmstadt's 1MWth power plant flue gas CO2 capture demonstration system, and Taiwan's ITRI Research Institute's 3kWth power plant flue gas CO2 capture pilot. All of them use a calcium cycle double fluidized bed cycle capture system to achieve CO2 capture and regeneration in flue gas.

[0006] All of the above technologies focus on CO2 capture and do not involve conversion and subsequent utilization. The research on CO2 capture and conversion in the published patents is mostly focused on catalysts. Since CO2 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 have some problems in CO2 capture and conversion. On the one hand, with the switching of the capture / conversion process, the coil absorbs heat for a while and takes heat for a while, which makes 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 direct supplementary combustion heating, there is often a problem of local overheating of the catalyst bed. Taking the commonly used CaO / CaCO3 adsorbent as an example, when the temperature is greater than 850-900℃, the adsorbent will melt and sinter, and the CO2 conversion process generally requires a reaction temperature of more than 500-700℃. If direct supplementary combustion heating is used, the temperature is too high and the adsorbent will melt and sinter and become inactivated; if the temperature is controlled to less than 800℃, the amount of supplementary heat 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.

[0007] CN202110287520.5 discloses a method for using the heat of a high-temperature molten heat carrier to supplement the heat in the process of generating synthesis gas by reacting carbon dioxide and carbon powder. The invention realizes the reduction of high-temperature carbon dioxide to carbon monoxide at conditions above 1000°C, and organically combines the strongly endothermic reaction process and the strongly exothermic process of the solidification latent heat of the molten heat carrier. The reaction process does not involve the carbon dioxide capture process, but only uses the heat of the high-temperature molten heat carrier for carbon dioxide conversion. However, the impurity composition of industrial high-temperature flue gas is relatively large. If industrial high-temperature flue gas and carbon powder are directly used for reaction, the generated synthesis gas will also contain impurity components, and the subsequent separation cost will increase. In addition, the process reaction involves frequent temperature changes from 50°C to 1500°C, which increases the energy consumption of the process.

[0008] CN200410064563.3 discloses a method and reactor for generating synthesis gas by reacting carbon dioxide, water vapor and hydrocarbons. On the one hand, the reaction does not involve a method for capturing carbon dioxide from industrial flue gas, but only converts and utilizes carbon dioxide to generate synthesis gas; on the other hand, the reactor involved in the method needs to operate under high temperature and high pressure, and most industrial flue gas is at normal pressure or slightly positive pressure, which requires pressure increase. High temperature and high pressure conditions also put forward higher requirements for equipment selection, and the high cost is not conducive to the promotion of technology.

[0009] 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 temperatures. 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 a long period of time.

[0010] 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.

[0011] At present, the patents and documents published at home and abroad are concentrated on CO2 capture and the research on the resource utilization of high-purity CO2, while there are few studies directly on the capture and in-situ resource conversion of CO2 in industrial high-temperature flue gas. Efficiently capture CO2 in industrial high-temperature flue gas and convert the captured CO2 into synthesis gas products in situ to facilitate the subsequent synthesis of chemical products such as light hydrocarbons with high added value. On the one hand, it can improve energy utilization and reduce carbon emissions, and on the other hand, it can avoid the high energy consumption caused by frequent cooling / heating involved in the capture process. In addition, the in-situ resource conversion of CO2 also solves the high cost of purification and transportation of CO2 after capture, as well as the safety hazards caused by storage, which is of great significance to improving the feasibility and economy of the entire CO2 emission reduction process. Summary of the invention

[0012] In view of the deficiencies of the above-mentioned background technology, the present invention provides a device and method for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which can capture carbon dioxide from industrial gas at high temperature and convert it into carbon monoxide or synthesis gas in situ.

[0013] The technical solution of the present invention is as follows:

[0014] A device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide comprises an adsorption system and a conversion system; the adsorption system comprises an adsorption reactor, a degassing heat supplement tank, a riser, and an adsorption system inclined tube; the conversion system comprises a conversion reactor, a waiting pipe, a degassing tank, a receiving tank, and a conversion system inclined tube; the riser is connected to the adsorption reactor, and the adsorption reactor is connected to the degassing heat supplement tank; the waiting pipe is respectively connected to the conversion reactor and the receiving tank, and the conversion reactor is connected to the degassing tank; the adsorption system inclined tube is respectively connected to the degassing heat supplement tank and the receiving tank; the conversion system inclined tube is respectively connected to the degassing heat supplement tank and the receiving tank; the conversion system inclined tube is respectively connected to the degassing tank and the riser.

[0015] The present invention provides a device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which is further characterized in that the adsorption and regeneration process is completed by transporting catalytic materials between two reactors, and the catalytic materials are transported by air and gravity.

[0016] The present invention provides a device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which is further characterized in that: the adsorption reactor is equipped with a bed layer composed of catalytic materials, and the conversion reactor is equipped with a bed layer composed of catalytic materials to be regenerated.

[0017] The present invention provides a device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which is further characterized in that an electric heater is provided in the degassing heat supplement tank to supplement the heat required for the process.

[0018] The present invention provides a device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which is further characterized in that a balance pipe is provided between the conversion reactor and the receiving tank to send the unregenerated catalytic material at the bottom of the conversion reactor to the receiving tank for regeneration.

[0019] The present invention provides a device for high-temperature capture and in-situ conversion of gas-carrying solid carbon dioxide, which is further characterized in that a gas distributor is arranged at the bottom of the receiving tank to evenly distribute the reducing gas, increase the gas-solid contact area, and fully complete the conversion process.

[0020] The present invention provides a device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which is further characterized in that the adsorption reaction is basically completed in the lifting pipe, and the conversion reaction is basically completed in the waiting pipe.

[0021] A method for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, using the above-mentioned device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, comprises the following steps:

[0022] 1) The carbon dioxide-containing gas enters the riser, mixes with the catalytic material from the inclined tube of the conversion system, and is sent to the adsorption reactor together. The carbon dioxide in the carbon dioxide-containing gas is adsorbed and captured by the catalytic material in the bed of the adsorption reactor, and purified gas is produced at the top of the adsorption reactor;

[0023] 2) The saturated catalytic material is degassed and heated before entering the adsorption system inclined tube, and then sent to the receiving tank by the adsorption system inclined tube to wait for regeneration;

[0024] 3) At the same time, the reducing gas enters the receiving tank, and the reducing gas is mixed with the saturated catalytic material and then sent to the conversion reactor through the waiting pipe;

[0025] 4) The adsorption saturated catalytic material reacts with the reducing gas, the carbon dioxide is reduced, and the catalytic material is regenerated at the same time. The regenerated catalytic material is degassed and sent to the riser through the inclined pipe of the conversion system, and synthesis gas is produced at the top of the conversion reactor.

[0026] The present invention provides a method for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which is further characterized in that: in step 3), the reducing gas is H2, CH4, C2H6, etc., or a mixture of two or more of these gases or a mixture of one or more of these gases and an inert gas. When these gases are introduced separately, the following reactions occur:

[0027] CO2+2H2=CO+H2O+H2

[0028] Or CO2+H2=CO+H2O

[0029] CO2+CH4=2CO+2H2

[0030] 2CO2+C2H6=4CO+3H2

[0031] The present invention provides a method for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, which is further characterized in that: the catalytic material described in step 1) refers to a material with dual functions of carbon dioxide adsorption and catalytic conversion, such as CaO material loaded with one or more active ingredients such as Co, Ni, lanthanide metals, etc.

[0032] Step 1) Catalytic material circulation amount A (m 3 / h) is determined by the amount of carbon dioxide to be adsorbed A1 (t / h) and the material adsorption capacity A2 (t / m 3 ), the specific calculation formula is as follows:

[0033] A=A1 / A2

[0034] The supplementary heat in step 2), i.e., the heat B (kJ / h) supplemented by the heater, depends on the heat loss B1 (kJ / h) of the conversion reactor, the heat absorbed during the regeneration process B2 (kJ / h), the total heat B3 (kJ / h) brought in by the reducing gas at the inlet of the conversion reactor, and the total heat B4 (kJ / h) taken away by the synthesis gas at the outlet of the conversion reactor. The specific calculation formula is as follows:

[0035] B=B1+B2-B3+B4

[0036] The beneficial effects of the present invention are as follows:

[0037] 1. Carbon dioxide adsorption and conversion regeneration are completed at similar temperatures, and the high-temperature catalytic material to be regenerated after capture and heating is used as the main heat source for the conversion and heating process, which can avoid the high energy consumption problem of capture cooling / conversion heating, improve energy utilization, and effectively reduce emission reduction costs.

[0038] 2. Carbon dioxide adsorption and conversion regeneration are completed in situ under similar pressure conditions, and the entire system is a closed system, which avoids excess pressure loss caused by gas transportation and reduces the high cost of purification and transportation;

[0039] 3. The reactor is inherently safe and has no power equipment. It can also avoid the interruption of the reaction caused by uneven reaction, accidental interruption of heat exchange medium, power equipment failure, etc. in traditional reactors;

[0040] 4. Simple process, easy to operate and maintain, low investment and small footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below in conjunction with the accompanying drawings:

[0042] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0043] In the figure: 1. Carbon dioxide-containing gas; 2. Rising pipe; 3. Adsorption reactor; 4. Purified gas outlet; 5. Degassing and heating tank; 6. Adsorption system inclined pipe; 7. Reducing gas; 8. Production pipe; 9. Conversion reactor; 10. Synthesis gas outlet; 11. Degassing tank; 12. Electric heater; 13. Conversion system inclined pipe; 14. Balance pipe; 15. Fresh catalyst; 16. Gas distributor; 17. Receiving tank. DETAILED DESCRIPTION

[0044] 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.

[0045] Raw material high temperature flue gas 409m 3 n / h as an example, the flue gas composition is as follows:

[0046] Flue gas composition ％v <![CDATA[CO2]]> 29.90 <![CDATA[H2O]]> 5.36 <![CDATA[N2]]> 59.17 <![CDATA[O2]]> 5.58

[0047] The flue gas temperature is 680℃ and the flue gas pressure is 10kPag. Figure 1 As shown:

[0048] 1) High-temperature flue gas containing carbon dioxide gas 1, 680℃ enters the riser 2 from the bottom, mixes with the catalytic material from the inclined tube 13 of the conversion system, and is sent to the adsorption reactor 3. The riser 2 is pre-installed with CaO-based catalytic material, and the catalytic material is loaded with Co active centers for catalytic adsorption reaction. The catalytic material settles to the bottom of the adsorption reactor 3 in the adsorption reactor 3. This process completes the high-temperature capture process of carbon dioxide. The reaction between CaO and CO2 is an exothermic reaction. The temperature of the purified flue gas after adsorption is 727℃, and the purified flue gas volume is 375m 3 n / h.

[0049] 2) The purified flue gas is sent out from the purified gas outlet 4 on the top of the adsorption reactor, and is sent to the chimney for discharge after dust removal and heat recovery by the cyclone separator. The adsorption-saturated catalytic material enters the degassing heat supplement tank 5, and after partial heat is supplemented by the electric heater 12, it enters the receiving tank 17 through the adsorption system inclined pipe 6.

[0050] 3) At the same time, excess H2 at 730°C is distributed as reducing gas 7 through gas distributor 16 and enters receiving tank 17. The reducing gas pneumatically conveys the saturated catalytic material through waiting pipe 8 to conversion reactor 9. In this process, the in-situ conversion of carbon dioxide is completed. The reducing gas 7 reacts with CaCO3 in the conversion reactor 9 to generate CaO, CO, H2 and water, and the saturated catalytic material is regenerated.

[0051] 4) In the conversion reactor 9, the synthesis gas is sent out of the device through the synthesis gas outlet 10, and the regenerated catalytic material settles to the bottom of the conversion reactor 9, slides into the degassing tank 11, and is sent to the riser 2 of the adsorption system by the conversion system inclined pipe 13. The catalytic material lost in the process is supplemented by the catalytic material tank with fresh catalyst 15 to the conversion reactor 9. A balance pipe 14 is set between the conversion reactor 9 and the receiving tank 17. The amount of synthesis gas produced by the reaction is about 206m 3 n / h, the synthesis gas temperature is about 630°C, and it is discharged through the synthesis gas outlet 10 of the conversion reactor 9. The expected composition of the synthesis gas is as follows:

[0052] Syngas composition ％v CO 29.17 <![CDATA[H2]]> 29.17 <![CDATA[CO2]]> 12.5 <![CDATA[H2O]]> 29.17 total 100

[0053] After the treatment in this embodiment, CO2 emission is reduced by about 990 t / a, and 1503 t / a of synthesis gas is produced as a by-product.

Claims

1. A device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, comprising an adsorption system and a conversion system; characterized in that: The adsorption system includes an adsorption reactor, a degassing and heating tank, a riser, and an adsorption system inclined tube; the conversion system includes a conversion reactor, a regeneration tube, a degassing tank, a receiving tank, and a conversion system inclined tube; the riser is connected to the adsorption reactor, and the adsorption reactor is connected to the degassing and heating tank; the regeneration tube is respectively connected to the conversion reactor and the receiving tank, and the conversion reactor is connected to the degassing tank; the adsorption system inclined tube is respectively connected to the degassing and heating tank and the receiving tank; the conversion system inclined tube is respectively connected to the degassing and heating tank and the receiving tank; the conversion system inclined tube is respectively connected to the degassing tank and the riser; a bed layer composed of catalytic material is arranged in the adsorption reactor, and a bed layer composed of catalytic material to be regenerated is arranged in the conversion reactor.

2. The device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide according to claim 1, characterized in that: An electric heater is provided in the degassing and heating tank.

3. The device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide according to claim 1, characterized in that: A balance pipe is arranged between the conversion reactor and the receiving tank.

4. The device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide according to claim 1, characterized in that: A gas distributor is arranged at the bottom of the receiving tank.

5. The device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide according to claim 1, characterized in that: A fresh catalyst inlet is arranged on the conversion reactor.

6. A method for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide, using the device for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide as claimed in claim 1, characterized in that The following steps are involved: 1) The carbon dioxide-containing gas enters the riser, mixes with the catalytic material from the inclined tube of the conversion system, and is sent to the adsorption reactor together. The carbon dioxide in the carbon dioxide-containing gas is adsorbed and captured by the catalytic material in the bed of the adsorption reactor, and purified gas is produced at the top of the adsorption reactor; 2) The saturated catalytic material is degassed and heated before entering the adsorption system inclined tube, and then sent to the receiving tank by the adsorption system inclined tube to wait for regeneration; 3) At the same time, the reducing gas enters the receiving tank, and the reducing gas is mixed with the saturated catalytic material and then sent to the conversion reactor through the waiting pipe; 4) The adsorption saturated catalytic material reacts with the reducing gas, the carbon dioxide is reduced, and the catalytic material is regenerated at the same time. The regenerated catalytic material is degassed and sent to the riser through the inclined pipe of the conversion system, and synthesis gas is produced at the top of the conversion reactor.

7. The method for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide according to claim 6, characterized in that: Step 3) 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.

8. The method for high-temperature capture and in-situ conversion of gas-carried solid carbon dioxide according to claim 6, 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.

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