Highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor

Abstract

The invention provides a highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor, which is 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 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 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 reaction is flexible, and raw materials and products in the in-situ conversion process can be selected as required; 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 highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor. 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 CO2 capture, utilization and storage, and each industry has formed 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.

[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. The direct supplementary combustion heating method often has the problem of overheating of the gas after combustion.

[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. The carbonate in this reaction needs to absorb heat to become molten carbonate, 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. 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 a highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor, which captures carbon dioxide from industrial flue gas at high temperature and converts it into carbon monoxide or synthesis gas in situ.

[0012] The technical solution of the present invention is as follows: a highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor, comprising a riser, a settling chamber, a dilute phase section, a waiting pipe, a gas rising section, a dense phase section, a heater and a downcomer pipe; the riser, the settling chamber, the dilute phase section, the waiting pipe and the dense phase section are connected in sequence; the gas rising section surrounds the outside of the dilute phase section and the waiting pipe, and the gas rising section is respectively connected to the outer wall of the settling chamber and the dense phase section; the downcomer pipe is respectively connected to the dense phase section and the riser.

[0013] The invention provides a highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor, which is further characterized in that: a cyclone separator is arranged on the top of the settling chamber to separate particles in the gas phase;

[0014] The invention provides a highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor, which is further characterized in that: a large slide valve is provided on the production pipe, and a small slide valve is provided on the lower agent pipe to control the flow rate and pressure of the fluidized particles;

[0015] The highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor of the present invention is further characterized in that: an electric heater is also provided, and the electric heater is connected to the dense phase section to supplement the heat lacking in the conversion;

[0016] The present invention discloses a highly integrated carbon dioxide high-temperature capture and in-situ conversion reactor, in which an adsorption reactor and a conversion reactor are integrated as a whole, and the switching of the adsorption and conversion processes is achieved through fluidized particles;

[0017] The carbon dioxide-containing gas is fed from the bottom of the lifting pipe, and together with the regenerated catalytic material, it enters the upper sedimentation chamber of the reactor from bottom to top through the lifting pipe. This process is the carbon dioxide adsorption process. After the catalytic material absorbs carbon dioxide, the solid phase enters the dilute phase section and then sinks, and sinks to the dense phase section at the bottom of the reactor through the waiting pipe. The waiting pipe and the dense phase section are separated by a barrier agent. The purified gas is separated from the dust carried in the gas phase by a cyclone separator and then leaves the device.

[0018] At the same time, the reducing gas enters the dense phase section from the bottom of the reactor, and reacts with the saturated adsorption catalytic material that settles from the waiting pipe, and the catalytic material is regenerated. The regenerated catalytic material is sent from the lower agent pipe to the riser; the carbon monoxide generated by the reaction accumulates outside the waiting pipe and is sent out of the device through the upper synthesis gas outlet. The dense phase section is equipped with an electric heater, and the insufficient heat is supplemented by the electric heater during the process.

[0019] The reducing gas refers to a gas that can react with CO2 to generate carbon monoxide or synthesis gas, such as H2, CH4, C2H6, 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:

[0020] CO2+2H2=CO+H2O+H2

[0021] Or CO2+H2=CO+H2O

[0022] CO2+CH4=2CO+2H2

[0023] 2CO2+C2H6=4CO+3H2

[0024] The catalytic material refers to a material having dual functions of carbon dioxide adsorption and catalytic conversion, such as a CaO material loaded with one or more active ingredients such as Co, Ni, and lanthanide metals.

[0025] The catalytic material circulation amount A (m3 / h) is determined by the amount of carbon dioxide to be adsorbed A1 (t / h) and the adsorption capacity of the catalytic material A2 (t / m 3 ), the specific calculation formula is as follows:

[0026] A=A1 / A2

[0027] The heat B (kJ / h) supplemented by the heater depends on the heat released by the catalytic material B1 (kJ / h), the heat loss of the reactor B2 (kJ / h), the heat absorbed by the conversion process B3 (kJ / h), the total heat brought in by the inlet reducing gas B4 (kJ / h) and the total heat taken away by the outlet carbon monoxide B5 (kJ / h). The specific calculation formula is as follows:

[0028] B=B2+B3-B1-B4+B5

[0029] The beneficial effects of the present invention are as follows:

[0030] 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;

[0031] 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;

[0032] 3. Flexible reaction, raw materials and products of in-situ conversion process can be selected according to needs;

[0033] 4. Simple process, easy to operate and maintain, low investment and small footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below in conjunction with the accompanying drawings:

[0035] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0036] In the figure: 1. Carbon dioxide-containing gas; 2. Rising pipe; 3. Synthesis gas outlet; 4. Settling chamber; 5. Cyclone separator; 6. Purified gas; 7. Dilute phase section; 8. Production pipe; 9. Large slide valve; 10. Gas rising section; 11. Dense phase section; 12. Heater; 13. Reducing gas; 14. Small slide valve; 15. Downgassing pipe. DETAILED DESCRIPTION

[0037] 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.

[0038] Raw material high temperature flue gas 409m 3 n / h as an example, the flue gas composition is as follows:

[0039] Flue gas composition ％v <![CDATA[CO2]]> 29.90 <![CDATA[H2O]]> 5.36 <![CDATA[N2]]> 59.17 <![CDATA[O2]]> 5.58

[0040] The flue gas temperature is 678℃ and the flue gas pressure is 10kPa.

[0041] The catalytic material used is a CaO-based catalytic material as an example. The catalytic material is loaded with Co active centers for catalytic adsorption reactions. The reaction between CaO and CO2 is a strongly exothermic reaction.

[0042] The carbon dioxide-containing gas 1 and the high-temperature flue gas of 1678°C enter the riser 2 from the bottom, and the catalytic material coming out of the dense phase section 11 enters the riser 2 through the lower agent pipe 15, on which a small slide valve 14 is arranged; the CaO in the riser 2 absorbs CO2 in the flue gas to react and generate CaCO3, and the purified gas 6 and the saturated adsorption catalytic material are pneumatically transported from bottom to top through the riser 2 to the settling chamber 4, where the gas and solid are separated, and the purified gas is sent out of the device after the small particles are removed by the cyclone separator 5.

[0043] The catalytic material settled in the settling chamber 4 enters the dilute phase section 7 and is settled to the dense phase section 11 through the waiting pipe 8 and the large slide valve 9 by gravity.

[0044] At the same time, excess H2 is injected into the dense phase section 11 as a reducing gas 13 in two ways. In the dense phase section 11, CaCO3 reacts with excess H2 at 730°C to produce CaO, CO, H2 and water. Carbon monoxide or synthesis gas accumulates in the gas rising section 10 and is sent out of the device through the synthesis gas outlet 3. The catalytic material is regenerated and then enters the dense phase section 11.

[0045] The reaction of H2 and CaCO3 is a strong endothermic reaction. Part of the heat required for the reaction is brought in by the catalytic material, and the insufficient part is supplemented by the heater 12.

[0046] During this process, the reaction endothermic load is 145kW, plus the energy difference between the inlet and outlet gases and the heat loss of the reactor, the total required heat load is 335kW. 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 600℃; in order to ensure that the catalytic material is not damaged, the maximum gas temperature needs to be controlled not to exceed 750℃.

[0047] The amount of syngas produced by the reaction is about 229m 3 n / h, the synthesis gas temperature is 630°C, and it is discharged through the synthesis gas outlet 3. The expected composition of the synthesis gas is as follows:

[0048] Element ％v CO 30 <![CDATA[H2]]> 30 <![CDATA[CO2]]> 10 <![CDATA[H2O]]> 30 total 100

[0049] After the treatment in this embodiment, CO2 emission is reduced by about 1262t / a, and 1619t / a of synthesis gas is produced as a by-product.

Claims

1. A highly integrated carbon dioxide high temperature capture and in-situ conversion reactor, characterized in that: It includes a lifting pipe, a settling chamber, a dilute phase section, a waiting pipe, a gas rising section, a dense phase section, a heater and a downcomer pipe; the lifting pipe, the settling chamber, the dilute phase section, the waiting pipe and the dense phase section are connected in sequence; the gas rising section surrounds the dilute phase section and the outside of the waiting pipe, and the gas rising section is respectively connected to the outer wall of the settling chamber and the dense phase section; the downcomer pipe is respectively connected to the dense phase section and the lifting pipe.

2. A highly integrated carbon dioxide high temperature capture and in-situ conversion reactor according to claim 1, characterized in that: A cyclone separator is arranged on the top of the settling chamber.

3. The highly integrated carbon dioxide high temperature capture and in-situ conversion reactor according to claim 1, characterized in that: A large sliding valve is set on the production pipe, and a small sliding valve is set on the lower agent pipe.

4. The highly integrated carbon dioxide high temperature capture and in-situ conversion reactor according to claim 1, characterized in that: It also includes an electric heater, which is connected to the dense phase section.

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