Energy integrated type high-temperature carbon dioxide trapping and in-situ conversion device and method

Abstract

The invention provides an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device and method, high-temperature carbon dioxide is captured from industrial flue gas and is converted into carbon monoxide or synthesis gas in an in-situ recycling manner, carbon dioxide adsorption and conversion are completed in situ under the approximate temperature and pressure conditions, and the energy-integrated high-temperature carbon dioxide capture and in-situ conversion device and method have the advantages that the energy-integrated high-temperature carbon dioxide capture and in-situ conversion effect is achieved; the energy utilization rate can be fully improved, 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 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; heat released in the reaction process is recycled through steam, and the energy utilization efficiency is improved; 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 an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device and method. 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. There are many sources of CO2 emissions in modern industrial production, such as cement, steel, electricity, coal chemical industry and refineries, which are all major CO2 emitters. In response to the CO2 emission problem, various industries have conducted research and exploration on the capture, utilization and storage of CO2. Each industry has formed a variety of technical methods for CO2 capture, utilization and storage 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] The details of the major domestic industrial pilot and demonstration projects are as follows: The CO2 capture demonstration project launched by Huaneng Group in December 2009 at Shanghai Shidongkou Second Power Plant uses 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 it was put into operation, the capture device 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 a 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 technology 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 and Germany's Darmstadt's 1MWth power plant flue gas CO2 capture demonstration system. Both 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, 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, which leads to a decrease in the effective gas concentration and severe dilution of the product.

[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] 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.

[0009] 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.

[0010] 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

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

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

[0013] An energy-integrated high-temperature carbon dioxide capture and in-situ conversion device comprises a reaction system and a regeneration system; the reaction system comprises a reactor, a degassing and heating tank, a chain bucket conveyor, and a steam coil; the regeneration system comprises a regenerator, a locking hopper, a heater, a dosing tank, and a conveying pipe; the steam coil is arranged in the reactor, and the heater is arranged in the regenerator; the reactor, the degassing and heating tank, the chain bucket conveyor, and the locking hopper are connected in sequence; the locking hopper is respectively connected to the dosing tank and the regenerator; one side of the conveying pipe is connected to the reactor, and the other side is connected to the regenerator.

[0014] The present invention provides an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device, which is further characterized in that: a catalytic material bed and a gas distributor are arranged in the reactor, and a steam coil is arranged between the catalytic material beds; a catalytic material bed to be regenerated and a gas distributor are arranged in the regenerator, and an electric heater is arranged between the catalytic material beds to be regenerated.

[0015] The present invention provides an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device, which is further characterized in that a slide valve is arranged on the delivery pipe.

[0016] The present invention provides an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device method, using the above energy-integrated high-temperature carbon dioxide capture and in-situ conversion device, comprising the following steps:

[0017] 1) The carbon dioxide-containing gas enters the 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 reaction is absorbed by the steam in the steam coil in the bed. The steam changes from saturated to superheated steam, and the bed and gas temperatures rise. The reaction produces purified gas, and the adsorbed saturated catalytic material is degassed and heated before being sent to the lock hopper to wait for regeneration.

[0018] 2) The adsorption saturated catalytic material settles from the lock hopper to the regenerator, and fresh catalytic material is added from the dosing tank to the lock hopper;

[0019] 3) The reducing gas enters the regenerator and passes through the regenerator bed in turn. The adsorbed saturated catalytic material reacts with the reducing gas, and the carbon dioxide is reduced to produce synthesis gas. The heat required for the reaction is supplemented by an external heat source through a heater. The regenerated catalytic material is sent back to the reactor through a delivery pipe for a cyclic reaction.

[0020] The present invention provides an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device, which is further characterized in that the adsorption process is integrated with the steam system to achieve the upgrading of low-grade heat sources to high-grade heat sources.

[0021] The present invention provides an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device, which is further characterized in that a gas-controlled lock hopper is provided to control the replenishment amount of fresh catalyst in the lock hopper.

[0022] The present invention provides an energy-integrated high-temperature carbon dioxide capture and in-situ conversion device, which is further characterized in that the catalyst switching between the adsorption reactor and the conversion reaction is achieved by relying on a chain bucket machine.

[0023] The reducing gas in step 1) refers to a gas that can react with CO2 to generate synthesis gas, such as 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 will occur:

[0024] CO2+2H2=CO+H2O+H2

[0025] Or CO2+H2=CO+H2O

[0026] CO2+CH4=2CO+2H2

[0027] 2CO2+C2H6=4CO+3H2

[0028] The catalytic material in step 1) refers to a material having 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.

[0029] Step 2) Catalytic material circulation amount A (m3 / 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:

[0030] A=A1 / A2

[0031] The heat B (kJ / h) added by the heater in step 3) depends on the heat loss B1 (kJ / h) of the reactor, the heat absorbed during the conversion process B2 (kJ / h), the total heat B3 (kJ / h) brought in by the inlet reducing gas, and the total heat B4 (kJ / h) taken away by the outlet synthesis gas. The specific calculation formula is as follows:

[0032] B=B1+B2-B3+B4

[0033] The beneficial effects of the present invention are as follows:

[0034] 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, and solve the high cost of purification and transportation after CO2 capture, as well as the safety hazards caused by storage;

[0035] 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;

[0036] 3. Use steam to recover the heat released during the reaction process and integrate it with the steam system to achieve comprehensive utilization of energy;

[0037] 4. Take full account of the low pressure of industrial high-temperature flue gas, minimize the pressure drop of the flue gas process, and ensure the continuous and stable reaction;

[0038] 5. Simple process, easy to operate and maintain, low investment and small footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0040] In the figure: 1. Carbon dioxide-containing gas; 2. Reactor; 3. Steam coil; 4. Purified gas outlet; 5. Degassing and reheating tank; 6. Chain bucket conveyor; 7. Lock hopper; 8. Fresh catalytic material; 9. Dosing tank; 10. Synthesis gas outlet; 11. Heater; 12. Regenerator; 13. Reducing gas; 14. Gas outlet; 15. Delivery pipe; 16. Sliding valve; 17. Gas seal gas; 18. Gas distributor. DETAILED DESCRIPTION

[0041] 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.

[0042] Raw material high temperature flue gas 409m 3 n / h as an example, the flue gas composition is as follows:

[0043] Flue gas composition ％v <![CDATA[CO2]]> 29.90 <![CDATA[H2O]]> 5.36 <![CDATA[N2]]> 59.17 <![CDATA[O2]]> 5.58

[0044] The flue gas temperature is 678℃ and the flue gas pressure is 10kPa. Figure 1 As shown:

[0045] 1) Carbon dioxide-containing gas 1, 678°C high-temperature flue gas enters reactor 2 from the bottom after being distributed by gas distributor 18.

[0046] 2) Reactor 2 is equipped with CaO-based catalytic material, which is loaded with Co active centers for catalytic adsorption reaction. The reaction between CaO and CO2 is a highly exothermic reaction. The heat released during the process is absorbed and recovered by the steam coil 3 in the catalytic material bed. After adsorption, the purified flue gas temperature is 727°C and the purified flue gas volume is 345m 3 n / h.

[0047] 3) The purified flue gas is sent out from the purified gas outlet 4 at the top of the reactor, and the adsorption saturated catalytic material enters the degassing and heating tank 5 for degassing. The gas is sent out with the purified flue gas, and the adsorption saturated catalytic material is sent into the locking hopper 7 by the chain bucket conveyor 6 at the bottom of the degassing and heating tank to wait for regeneration.

[0048] 4) The adsorption saturated catalytic material is gravity-precipitated from the lock hopper 7 to the regenerator 12. The lock hopper 7 is sealed with a gas seal 17. The gas from the gas outlet 14 is combined with the gas from the purified gas outlet 4. The gas heat is recovered and the gas is sent to the chimney for discharge after cooling. Fresh catalytic material 8 is added to the lock hopper 7 from the dosing tank 9.

[0049] 5) The reducing gas 13 is distributed from the gas distributor 18 and enters the regenerator 12. Excess H2 at 730°C reacts with CaCO3 in the regenerator 12 to generate CaO, CO, H2 and water. The synthesis gas is dust-removed and sent out of the device through the synthesis gas outlet 10. The reaction between H2 and CaCO3 is a strong endothermic reaction, and the heat required for the reaction is provided by the electric heater 11.

[0050] During this process, the reaction endothermic load is 173kW, plus the energy difference between the inlet and outlet gases and the heat loss of the reactor, the total required heat load is 227kW. During 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℃; and in order to ensure that the catalytic material is not damaged, the maximum gas temperature needs to be controlled not to exceed 750℃.

[0051] 6) The regenerated catalytic material is sent back to the reactor 2 through the delivery pipe 15, and the cycle continues. A slide valve 16 is provided on the delivery pipe 15.

[0052] The amount of syngas produced by the reaction is about 265m 3 n / h, the synthesis gas temperature is 630°C, and it is discharged through the synthesis gas outlet 10 of the regenerator 12. The expected composition of the synthesis gas is as follows:

[0053] Element ％v CO 31.06 <![CDATA[H2]]> 31.06 <![CDATA[CO2]]> 6.82 <![CDATA[H2O]]> 31.06 total 100

[0054] After the treatment in this embodiment, CO2 emission is reduced by about 1424t / a, and 1780t / a of synthesis gas is produced as a by-product.

Claims

1. An energy-integrated high-temperature carbon dioxide capture and in-situ conversion device, comprising a reaction system and a regeneration system; characterized in that: The reaction system includes a reactor, a degassing and heating tank, a chain bucket conveyor, and a steam coil; the regeneration system includes a regenerator, a locking hopper, a heater, a dosing tank, and a conveying pipe; the steam coil is arranged in the reactor, and the heater is arranged in the regenerator; the reactor, the degassing and heating tank, the chain bucket conveyor, and the locking hopper are connected in sequence; the locking hopper is respectively connected to the dosing tank and the regenerator; one side of the conveying pipe is connected to the reactor, and the other side is connected to the regenerator.

2. The energy-integrated high-temperature carbon dioxide capture and in-situ conversion device according to claim 1, characterized in that: The reactor is provided with a catalytic material bed and a gas distributor, and a steam coil is provided between the catalytic material beds; the regenerator is provided with a catalytic material bed to be regenerated and a gas distributor, and an electric heater is provided between the catalytic material beds to be regenerated.

3. The energy-integrated high-temperature carbon dioxide capture and in-situ conversion device according to claim 1, characterized in that: A slide valve is provided on the delivery pipe.

4. An energy-integrated high-temperature carbon dioxide capture and in-situ conversion method, using the energy-integrated high-temperature carbon dioxide capture and in-situ conversion device as claimed in claim 2, characterized in that The following steps are involved: 1) The carbon dioxide-containing gas enters the 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 reaction is absorbed by the steam in the steam coil in the bed. The steam changes from saturated to superheated steam, and the bed and gas temperatures rise. The reaction produces purified gas, and the adsorbed saturated catalytic material is degassed and heated before being sent to the lock hopper to wait for regeneration. 2) The adsorption saturated catalytic material settles from the lock hopper to the regenerator, and fresh catalytic material is added from the dosing tank to the lock hopper; 3) The reducing gas enters the regenerator and passes through the regenerator bed in turn. The adsorbed saturated catalytic material reacts with the reducing gas, and the carbon dioxide is reduced to produce synthesis gas. The heat required for the reaction is supplemented by an external heat source through a heater. The regenerated catalytic material is sent back to the reactor through a delivery pipe for a cyclic reaction.

5. The energy-integrated high-temperature carbon dioxide capture and in-situ conversion method according to claim 4, characterized in that: The gas produced by the lock hopper is combined with the purified gas produced by the reactor, and the gas heat is recovered and cooled before being discharged to the chimney.

6. The energy-integrated high-temperature carbon dioxide capture and in-situ conversion method according to claim 4, characterized in that: The catalytic material in step 1) is a CaO material loaded with one or more of Co, Ni and lanthanide metal active ingredients.

7. The energy-integrated high-temperature carbon dioxide capture and in-situ conversion method according to claim 4, 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.

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