Integrated system and device for capturing and in-situ conversion of carbon dioxide in industrial flue gas containing reducing components

Abstract

The invention provides a carbon dioxide capture and in-situ conversion integrated system and device for industrial flue gas containing reducing components. The system comprises a flue gas pretreatment system and a chemical looping carbon dioxide capture and in-situ conversion system. The flue gas pretreatment system circulates among a plurality of reactors through an oxygen carrier, industrial flue gas carbon dioxide capture and efficient recovery of reducing components are achieved, the captured carbon dioxide enters the chemical-looping carbon dioxide capture and in-situ conversion system, a difunctional material with carbon dioxide capture and conversion active sites is used, and the carbon dioxide capture and conversion efficiency is improved. The continuous capture and in-situ conversion integrated process of carbon dioxide is realized, and high-added-value products are prepared. The system and the device can realize integration of capturing and conversion of carbon dioxide in industrial flue gas containing reducing components and efficient recovery of effective components at the same time, and have important practical significance on resource utilization and green low-carbon development of the industrial flue gas.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas treatment and relates to the capture and in-situ conversion of carbon dioxide from industrial flue gas containing reducing components, and specifically relates to an integrated system and device for the capture and in-situ conversion of carbon dioxide from industrial flue gas containing reducing components. Background Art

[0002] As the industrial sector becomes more and more dependent on fossil energy sources such as coal, oil, and natural gas, industrial flue gas emissions continue to increase, and the inherent air pollutants contained in them have become an important factor in exacerbating global warming and climate change, making the treatment of industrial flue gas an important area of ​​concern. Traditional flue gas treatment usually adopts dust removal, desulfurization and denitrification, residual pressure power generation or waste heat recovery and then discharge. This treatment mode has obvious limitations: on the one hand, it fails to control CO2 emissions according to the emission characteristics of different flue gases; on the other hand, it fails to fully realize the resource utilization of other components. It is worth noting that industrial flue gas containing reducing components, represented by blast furnace gas, converter gas, coke oven gas and blue charcoal flue gas, has significant potential for resource utilization, including nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2) and methane (CH4). Therefore, the development of new treatment technologies that can effectively reduce CO2 emissions and improve the resource utilization efficiency of flue gas components has become a key breakthrough in achieving pollution reduction and carbon reduction and high-value utilization of industrial flue gas. Technological breakthroughs in this field will have important theoretical significance and practical value in promoting the transformation of related industries to clean production and green, low-carbon and sustainable development.

[0003] Industrial flue gas has the characteristics of large emission and complex distribution. Most of the reducing components (H2, CO and CH4, etc.) are burned, resulting in resource waste and secondary pollution. The diversity of circulating media in chemical chain technology provides a powerful way to recycle the two effective components H2 and CO in industrial flue gas, but it does not consider how to deal with the captured CO2. Usually, the captured CO2 needs to go through purification, compression, transportation, storage and conversion steps, facing problems such as complex process, low efficiency, large energy loss, high equipment cost and high safety risk. In order to reduce the energy consumption cost of carbon dioxide capture and utilization, carbon dioxide capture and in-situ conversion technology came into being. This technology can convert captured CO2 into value-added chemicals on site, reduce compression and transportation costs and corresponding equipment, and has higher environmental and economic feasibility. Therefore, it is of great significance to propose a system that can simultaneously realize the integrated capture and conversion of flue gas CO2 and the efficient recovery of other components. Summary of the invention

[0004] The present invention aims at the efficient recovery of effective components and the carbon dioxide emission problem in industrial flue gas containing reducing components, and provides an integrated system and device for carbon dioxide capture and in-situ conversion of industrial flue gas containing reducing components.

[0005] In the first aspect of the present invention, there is provided an integrated system for carbon dioxide capture and in-situ conversion of industrial flue gas containing reducing components, which has the following technical features: It includes a flue gas pretreatment system and a chemical looping carbon dioxide capture and in-situ conversion system.

[0006] Among them, the flue gas pretreatment system mainly includes a reduction reactor and an oxidation reactor. The oxygen carrier circulates between multiple reactors. The oxygen carrier is reduced due to the consumption of lattice oxygen in the reduction stage; in the oxidation stage, water vapor (carbon dioxide or air) is introduced to generate hydrogen (carbon monoxide or nitrogen), realizing the efficient recovery of reducing components and the capture of carbon dioxide, and the captured carbon dioxide enters the chemical looping carbon dioxide capture and in-situ conversion system.

[0007] Among them, the chemical looping carbon dioxide capture and in-situ conversion system includes a capture reactor and an in-situ conversion reactor, and uses a bifunctional material with carbon dioxide capture and conversion active sites to realize the integrated process of continuous carbon dioxide capture and in-situ conversion, and produce high-value-added products.

[0008] Preferably, the oxygen carrier is a metal oxygen carrier, and specifically, it can be selected from: iron-based oxygen carrier, nickel-based oxygen carrier, copper-based oxygen carrier, manganese-based oxygen carrier, etc.

[0009] Preferably, the bifunctional material used in the chemical looping carbon dioxide capture and in-situ conversion system has an adsorption active component of alkali metal oxide and alkaline earth metal oxide, and a catalytic active component of a metal catalyst.

[0010] The chemical looping carbon dioxide capture and in-situ conversion technology is mainly based on the cycle of carbonation and decarbonation occurring between alkali metal oxides, alkaline earth metal oxides and their carbonates. The main alkali metal adsorbents are sodium-based adsorbents and potassium-based adsorbents, and the main alkaline earth metal adsorbents are calcium-based adsorbents and magnesium-based adsorbents.

[0011] The main catalysts for the chemical looping carbon dioxide capture and in-situ conversion technology are single-metal catalysts such as platinum, ruthenium, nickel, iron, etc. and corresponding bimetallic catalysts.

[0012] In the second aspect of the present invention, there is provided an integrated device for carbon dioxide capture and in-situ conversion of industrial flue gas containing reducing components using the above system, which is characterized by including the following steps:

[0013] (1) Introduce the flue gas into a reduction reactor filled with an oxygen carrier, oxidize the reducing components (such as carbon monoxide, hydrogen, etc.) in the flue gas using the oxygen carrier, and then obtain the reduced oxygen carrier after gas-solid separation; the reduced oxygen carrier refers to the product after the oxygen carrier combines with the reducing gas;

[0014] (2) Pass the reduced oxygen carrier obtained in step (1) into an oxidation reactor, introduce air (water or carbon dioxide) to oxidize the reduced oxygen carrier into an oxygen carrier, and then obtain the oxygen carrier after gas-solid separation;

[0015] (3) Pass the gas components obtained in step (1) into a capture reactor, adsorb CO2 with the bifunctional material, and then obtain the carbonated bifunctional material after gas-solid separation; the carbonated bifunctional material refers to the product after the bifunctional material combines with carbon dioxide;

[0016] (4) Pass the carbonated bifunctional material obtained in step (3) into an in-situ conversion reactor, introduce the corresponding gas for an in-situ conversion reaction, and obtain an adsorbent and a target product after the in-situ conversion reaction.

[0017] The in-situ conversion reactor converts carbon dioxide into high-value chemicals through different reaction paths, such as methanation reaction (MET), reverse water gas shift reaction (RWGS), dry reforming of methane reaction (DRM), and oxidative dehydrogenation (ODH), etc. (as shown in Equations 1-4).

[0018] CO2 + 4H2 = CH4 + 2H2O ΔH = -165 kJ / mol (1)

[0019] CO2 + H2 = CO + H2O ΔH = +41.2 kJ / mol (2)

[0020] CO2 + CH4 = 2CO + 2H2 ΔH = +247 kJ / mol (3)

[0021] C2H6 + 1 / 2O2 = C2H4 + H2O ΔH = -105 kJ / mol (4)

[0022] Preferably, the corresponding gas introduced into the in-situ conversion reactor refers to hydrogen, methane, alkanes, etc.

[0023] Preferably, the target product after the in-situ conversion reaction can be, but is not limited to, methane, syngas (H2, CO), and olefins, etc.

[0024] Preferably, pass the oxygen carrier obtained in the oxidation reactor into the reduction reactor; pass the bifunctional material obtained in the conversion reactor into the capture reactor to realize the recycling of the oxygen carrier and the bifunctional material.

[0025] Preferably, the pressure in the reactor is above 1 atmosphere.

[0026] Preferably, the temperature in the in-situ conversion reactor is 300 - 850 °C.

[0027] Preferably, the temperature in the capture reactor is 600 - 800 °C.

[0028] Specifically, compared with the prior art, the present invention has the following technical innovations and remarkable advantages:

[0029] (1) The integrated system for industrial flue gas carbon dioxide capture and in-situ conversion provided by the present invention realizes the efficient recovery of components in the flue gas containing reducing components and the integration of CO2 capture and conversion, providing a new solution for the efficient and clean comprehensive utilization of industrial flue gas;

[0030] (2) The flue gas pretreatment system mentioned in the present invention uses an oxygen carrier as a circulating medium. The oxygen carrier is reduced due to the consumption of lattice oxygen in the reduction stage; in the oxidation stage, H2O (CO2 or air) is introduced to produce H2 (CO or N2), while realizing the efficient recovery of reducing gases and CO2 capture;

[0031] (3) The chemical looping carbon dioxide capture and in-situ conversion system mentioned in the present invention uses a bifunctional material with CO2 capture and conversion active sites to realize the continuous capture and in-situ conversion of CO2, avoiding processes such as gas compression and pipeline transportation, reducing equipment investment and improving efficiency; turning the environmentally harmful greenhouse gas carbon dioxide into a treasure, converting it into syngas, and then, through processes such as Fischer-Tropsch synthesis, it can be transformed into high-value chemicals, generating certain economic value;

[0032] (4) In the flue gas pretreatment system, the oxygen carrier obtained in the oxidation reactor is introduced into the reduction reactor; in the chemical looping carbon dioxide capture and in-situ conversion system, the bifunctional material obtained in the in-situ conversion reactor is introduced into the capture reactor to realize the cyclic use of the oxygen carrier and the bifunctional material.

[0033] In summary, the system provided by the present invention realizes the integration of the recovery of effective components in industrial flue gas containing reducing components and CO2 capture and conversion through the flue gas pretreatment and the chemical looping carbon dioxide capture and in-situ conversion process, which has important practical significance for the resource utilization of industrial flue gas and green and low-carbon development. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a process flow block diagram of the integrated technology for industrial flue gas carbon dioxide capture and in-situ conversion containing reducing components;

[0035] Figure 2 Schematic process flow diagram of a chemical looping water splitting coupled with chemical looping carbon dioxide capture and in-situ conversion of methane dry reforming system for steel plant flue gas

[0036] Figure 3 Schematic process flow diagram of a chemical looping combustion coupled with chemical looping carbon dioxide capture and in-situ conversion of reverse water gas shift system for semi-coke tail gas Specific embodiments

[0037] The present invention will be further described below in conjunction with embodiments

[0038] Embodiment 1

[0039] This embodiment provides a system for coupling chemical-looping water splitting, calcium looping, and dry reforming of methane to syngas to achieve integrated carbon dioxide capture and conversion and efficient recovery and utilization of reducing components. Taking Fe2O3 and CaO-Ni as the oxygen carrier and bifunctional material respectively, the specific process is as follows: Blast furnace gas and converter gas from a steel plant with an annual output of 0.1 billion tons are introduced into the fuel reactor, with gas flow rates of 7.20 kmol / s and 0.50 kmol / s respectively, and gas contents of: 3.0% H2, 21.6% CO, 4.0% CH4, 53.2% N2, 21.8% CO2 and 9.0% H2, 62.9% CO, 5.0% O2, 16.6% N2, 19.1% CO2. The solid component is the solid component separated from the air reactor by gas-solid separation. The Fe2O3 feed is 5.62 kmol / s, the temperature of the fuel reactor is 650 °C, the operating pressure is ~1 atm, and the CO conversion rate is 97.9%. The water feed to the steam reactor is 1.22 kmol / s, and the solid feed is the solid component separated from the fuel reactor by gas-solid separation. The temperature of the steam reactor is 650 °C, the operating pressure is ~1 atm, and the FeO conversion rate is 50%. The air feed to the air reactor is 2.92 kmol / s, and the solid feed is the solid component separated from the steam reactor by gas-solid separation. The temperature of the air reactor is 650 °C, the operating pressure is ~1 atm, and Fe3O4 and FeO are completely oxidized by air to form Fe2O3. The air feed to the combustion reactor is 0.88 kmol / s, and the gas feed is the gas component separated from the fuel reactor by gas-solid separation. The temperature of the combustion reactor is 650 °C, the operating pressure is ~1 atm, and CH4, H2, and O2 basically react completely. The circulating CaO feed to the carbonation reactor is 17.84 kmol / s, and the gas feed is the gas component separated from the combustion reactor by gas-solid separation. The temperature of the carbonation reactor is 650 °C, the operating pressure is ~1 atm, and the CaO conversion rate is 89.8%. The CH4 feed to the reforming reactor is 8.74 kmol / s, and the solid feed is the solid component separated from the carbonation reactor by gas-solid separation and fresh CaCO3 feed (0.18 kmol / s). The temperature of the reforming reactor is 850 °C, the operating pressure is ~1 atm, and CO2, CH4, and H2O are completely converted to CO and H2. At equilibrium, the purity of the syngas (dry basis) is 97.87%, and the H2 / CO is about 2.02.

[0040] Example 2

[0041] This embodiment provides a system for coupling chemical-looping combustion, calcium looping, and reverse water-gas shift to syngas to achieve integrated carbon dioxide capture and conversion and efficient recovery and utilization of reducing components. Taking Fe2O3 and CaO-Ni as the oxygen carrier and bifunctional material respectively, the specific process is as follows: A standard volume of 7×10 61 cubic meter of semi-coke tail gas, with a gas flow rate of 4.14 kmol / s and gas composition: 26.3% H2, 15.7% CO, 7.1% CH4, 44.2% N2, 6.3% CO2, and 0.4% O2. The solid component is the solid component after gas-solid separation from the air reactor. The Fe2O3 feed is 2.92 kmol / s, the fuel reactor temperature is 900 °C, and the operating pressure is ~1 atm. The air feed to the air reactor is 6.95 kmol / s, and the solid feed is the solid component after gas-solid separation from the fuel reactor. The air reactor temperature is 900 °C, the operating pressure is ~1 atm, and FeO and Fe3O4 are completely oxidized by air to form Fe2O3. The circulating CaO feed to the carbonation reactor is 8.24 kmol / s, and the gas feed is the gas component after gas-solid separation and drying from the fuel reactor. The carbonation reactor temperature is 650 °C, the operating pressure is ~1 atm, and the CaO conversion rate is 89.8%. The H2 feed to the reforming reactor is 5.36 kmol / s, and the solid feed is the solid component after gas-solid separation from the carbonation reactor and the fresh CaCO3 feed (0.08 kmol / s). The reforming reactor temperature is 650 °C, the operating pressure is ~1 atm, the CO2 conversion rate is 75%, and the CaCO3 conversion rate is 55%. At equilibrium, the purity of the syngas (dry basis) is 95.21%, and the H2 / CO is approximately 5.63.

Claims

1. An integrated system and device for carbon dioxide capture and in-situ conversion from industrial flue gas containing reducing components, characterized in that, It includes: A flue gas pretreatment system and a chemical looping carbon dioxide capture and in-situ conversion system. The flue gas pretreatment system mainly includes a reduction reactor and an oxidation reactor; Using an oxygen carrier as a circulating medium, the oxygen carrier is reduced due to the consumption of lattice oxygen in the reduction stage; in the oxidation stage, water vapor (carbon dioxide or air) is introduced to produce hydrogen (carbon monoxide or nitrogen), realizing the efficient recovery of reducing components and capturing carbon dioxide, and the captured carbon dioxide enters the chemical looping carbon dioxide capture and in-situ conversion system; The chemical looping carbon dioxide capture and in-situ conversion system includes a capture reactor and an in-situ conversion reactor, and uses a bifunctional material with carbon dioxide capture and conversion active sites to realize the integrated process of continuous carbon dioxide capture and in-situ conversion, and produce high-value-added products.

2. The system according to claim 1, wherein It includes the following steps: (1) Introduce the flue gas into the reduction reactor filled with the oxygen carrier, oxidize the reducing components (carbon monoxide, hydrogen, etc.) in the flue gas by using the oxygen carrier, and then obtain the reduced oxygen carrier after gas-solid separation; the reduced oxygen carrier refers to the product after the oxygen carrier combines with the reducing gas; (2) Introduce the reduced oxygen carrier obtained in step (1) into the oxidation reactor, introduce air (water or carbon dioxide) to oxidize the reduced oxygen carrier into the oxygen carrier, and then obtain the oxygen carrier after gas-solid separation; (3) Introduce the gas at the outlet of the reduction reactor obtained in step (1) into the capture reactor, carbon dioxide is adsorbed by the bifunctional material, and then the carbonated bifunctional material is obtained after gas-solid separation; The carbonated bifunctional material refers to the product after the bifunctional material combines with carbon dioxide; (4) Introduce the carbonated bifunctional material obtained in step (3) into the in-situ conversion reactor, introduce the corresponding gas for in-situ conversion reaction, and obtain the bifunctional material and the target product after the in-situ conversion reaction.

3. The system according to claim 2, wherein Introduce the oxygen carrier obtained in the oxidation reactor into the reduction reactor; introduce the bifunctional material obtained in the in-situ conversion reactor into the capture reactor to realize the cyclic use of the oxygen carrier and the bifunctional material.

4. The system according to claim 2, wherein The in-situ conversion reactor converts carbon dioxide into high-value-added chemicals through different reaction paths, such as methanation reaction (MET), reverse water gas shift reaction (RWGS), dry reforming of methane reaction (DRM), and oxidative dehydrogenation (ODH), etc.

5. The system according to claim 2, wherein The corresponding gas introduced into the in-situ conversion reactor refers to hydrogen, methane, alkane, etc., and the target products after the in-situ conversion reaction are methane, syngas (H2, CO), or olefins, etc.

6. The system according to claim 1 or 2, characterized in that The oxygen carrier is a metal oxygen carrier, and specifically, it can be selected from: iron-based oxygen carrier, nickel-based oxygen carrier, copper-based oxygen carrier, manganese-based oxygen carrier, etc.

7. The system according to claim 1 or 2, characterized in that, For the adsorption-catalysis bifunctional material, the adsorption active components are alkali metal oxides and alkaline earth metal oxides. The main alkali metal adsorbents are sodium-based adsorbents and potassium-based adsorbents, and the main alkaline earth metal adsorbents are calcium-based adsorbents and magnesium-based adsorbents; the catalytic active components are metal catalysts, including single-metal catalysts such as platinum, ruthenium, nickel, iron, etc. and corresponding bimetallic catalysts.

8. The system according to claim 1 or 2, characterized in that, Among them, The reactor is a fixed bed, fluidized bed or moving bed, and the pressure in the reactor is above 1 atmosphere.

9. The system according to claim 1 or 2, wherein The temperature in the in-situ conversion reactor is 300 - 850 °C.

10. The system according to claim 1 or 2, characterized in that, The temperature in the capture reactor is 600 - 800 °C.

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