System and method for producing co gas by co2 carbon-free deoxidation

Abstract

The application discloses a system and method for preparing CO gas by CO2 carbon-free deoxidation, a steelmaking induction furnace is transformed into a closed gas making furnace, CO2 or industrial tail gas containing high concentration CO2 is taken as raw gas and is introduced into an oxygen-saturated iron-based melt at 1600-1800 DEG C through a bottom blowing element, high concentration CO gas is prepared, FeO deoxidation product of CO2 is migrated to a slag phase and oxygen removal and iron reduction regeneration are realized through an external electric field mode, a new method for preparing CO by CO2 carbon-free deoxidation is constructed with the oxygen-saturated iron-based melt solute iron element as an oxygen transfer medium, meanwhile, the energy required by CO2 decomposition endothermic and molten slag electrochemical reduction can be generated through photovoltaic, wind, hydraulic or nuclear power generation devices, green electricity is used as an energy carrier to realize efficient quality-energy conversion of CO2 and CO under the condition of no additional carbon input, a carbon neutral cycle process of steel-chemical cogeneration coupling is opened up, and the application has good application and development prospect.

Description

Technical Field

[0001] This invention relates to the field of CO2 gas resource utilization and efficient CO gas preparation and production in the iron and steel metallurgical process, and particularly to a system and method for producing CO gas using CO2 without carbon deoxidation. Background Technology

[0002] Currently, both domestic and international efforts are exploring the use of artificial photosynthesis to produce hydrocarbons in order to reduce atmospheric CO2 concentration. This involves using green energy to synthesize hydrocarbons from CO2 with water or hydrogen. However, CO2 has high bond energy, resulting in low yields from direct CO2 hydrogenation. Therefore, current technological routes primarily involve removing an oxygen atom from CO2 to generate more reactive CO, which then combines with water or hydrogen to form liquid hydrocarbons. Currently, industrial catalytic processes require at least 1.33 eV of energy to convert 1 mol of CO2 into CO, along with an additional 1.5 eV of energy and a precious metal catalyst. The energy required to synthesize hydrocarbons far exceeds the energy that can be stored in their chemical bonds. To improve conversion efficiency and reaction rate, high-temperature and high-pressure environments are typically required. Currently, CO2 conversion rates are generally between 40% and 60%. Whether the efficient mass and heat transfer environment of the molten pool in steelmaking processes can be utilized to convert CO2 into CO for the chemical industry, thereby achieving deep coupling of steelmaking and chemical co-production—resulting in carbon reduction at the steel source and carbon fixation at the chemical end—is a key research topic of ongoing concern for steel metallurgists.

[0003] The Chinese invention patent "A System and Method for Preparing CO Gas Using CO2" (application number: 202111603595.6) proposes a method based on the high decomposition rate of CO2 gas in oxygen-saturated iron-based melts. This method involves introducing high-purity CO2 gas into an oxygen-saturated Fe-OC melt at a temperature between 1600℃ and 1800℃ through a bottom-blowing element placed at the bottom of a closed gasifier (modified from a steelmaking induction furnace) [CO2 + Fe → CO + FeO]. The gaseous products are then separated by a gas separation device to produce high-purity CO gas. While this method can efficiently and on a large scale utilize CO2 gas, the deoxidation product FeO is regenerated into metallic iron through reduction with carbonaceous materials [FeO + C → Fe + CO], thus achieving iron recycling. Essentially, this process still involves using an external carbon source to "reduce carbon emissions" by producing CO gas through a CO2 decarbonization reaction [CO2 + C → 2CO], indirectly increasing carbon emissions. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to utilize the large amount of CO2 gas present in the metallurgical system and efficiently produce CO gas without additional carbon input.

[0005] The basic principle of this invention is as follows:

[0006] Based on this, the applicant proposes to transform the steelmaking induction furnace into a closed gasification furnace. CO2 or industrial tail gas containing high concentrations of CO2 is introduced as raw material gas through bottom blowing elements into an oxygen-saturated iron-based melt at 1600℃-1800℃ to produce high-concentration CO gas. The CO2 deoxidation product FeO migrates to the slag phase, and oxygen removal and iron reduction and regeneration are achieved through an external electric field. This constructs a new method for producing CO2 without carbon deoxidation using iron element as the oxygen transfer medium in an oxygen-saturated iron-based melt. At the same time, the energy required for CO2 decomposition endothermic and slag electrochemical reduction heat consumption can be generated by photovoltaic, wind, hydropower or nuclear power generation devices. Using green electricity as the energy carrier, the efficient mass-energy conversion of CO2 and CO is achieved without additional carbon input, opening up a carbon-neutral cycle process coupled with steel-chemical co-production, which has good application and development prospects.

[0007] This invention first provides a system and method for producing CO gas from CO2 without carbon deoxygenation, including a closed gasifier, an electromagnetic induction heating coil, and an external DC power supply electrolysis system. The gaseous products generated by the closed gasifier are connected to a gaseous product dust removal device via a first pipe. The purified gaseous products enter the hot fluid inlet of a heat exchanger via a second pipe. The cooled gaseous products are connected to a gas composition detection device via a third pipe, then to a first booster compressor via a fourth pipe. The pressurized gaseous products are connected to a pneumatic three-way ball valve via a fifth pipe. The first outlet of the pneumatic three-way ball valve is connected to a gas separation device via a sixth pipe, and the second outlet of the pneumatic three-way ball valve is used for venting. The high-purity CO gas produced by the gas separation device is connected to the inlet of a second booster compressor via a seventh pipe. After pressurization, the high-purity CO gas is transported and stored in a CO gas storage tank via an eighth pipe. The gas separation device produces… High-purity CO2 gas is connected to the first shut-off valve via the ninth pipeline, and then enters the inlet of the third booster compressor via the tenth pipeline. After being pressurized, the high-purity CO2 gas is transported and stored in the CO2 gas storage tank via the eleventh pipeline. External high-purity CO2 gas is connected to the second shut-off valve via the twelfth pipeline, and then transported to the CO2 gas storage tank via the thirteenth pipeline. The high-purity CO2 gas in the CO2 gas storage tank enters the cold fluid inlet of the heat exchanger via the fourteenth pipeline. After heat exchange, it enters the third shut-off valve via the fifteenth pipeline, and then enters the pressure and flow regulating valve via the sixteenth pipeline. The high-purity CO2 gas after pressure and flow regulation enters the CO2 gas flow meter inlet via the seventeenth pipeline. After flow measurement, it enters the bottom blowing element installed at the bottom of the sealed gasifier via the eighteenth pipeline. The gaseous products generated by the positive electrode of the external DC power supply enter the fourth booster compressor and the fourth shut-off valve via the positive electrode sealing device and the nineteenth pipeline.

[0008] Furthermore, the closed gasifier has a tonnage of 5t to 100t, with an electromagnetic induction heating coil installed outside the furnace body and an external DC power supply electrolysis system installed on the upper part of the closed gasifier.

[0009] Furthermore, it also includes a hopper installed on top of the enclosed gasifier.

[0010] Furthermore, the steam generated by the heat exchanger is transported to the steam inlet of the gas separation unit via the nineteenth pipe for the regeneration and separation of the adsorbed gas.

[0011] Furthermore, the energy required for the heat absorption of CO2 decomposition and the heat consumption of DC electrolytic reduction of molten slag is generated by photovoltaic, wind, hydropower or nuclear power generation devices.

[0012] This invention also provides a method for producing CO gas using carbon-free deoxygenation of CO2, comprising the following steps:

[0013] (1) A system for producing CO gas from CO2 without carbon deoxygenation as described in claim 1 is provided;

[0014] (2) Entering the oxygen-saturated iron-based melt preparation stage, electrolytic pure iron is used as the raw material for the molten pool metal phase and is loaded into the closed gasifier. High-purity magnesium oxide is added as a slag conditioner. The raw material for the metal phase is melted by electricity and the temperature of the molten pool is raised to above 1600℃. The external high-purity CO2 gas is stored in the CO2 gas storage tank and connected to the bottom blowing element inlet through a heat exchanger, pneumatic ball valve, pressure and flow regulating valve and CO2 gas flow meter. High-purity CO2 gas is continuously introduced from the bottom blowing element located at the bottom of the closed gasifier. During the melting process, the gas phase products are dusted and heat exchanged. The volume fraction of CO gas and CO2 gas in the gas phase is detected by an online gas phase composition detection device. When the volume fraction of CO gas in the gas phase products reaches above 85%, the oxygen-saturated iron-based melt preparation stage is completed.

[0015] (3) Entering the CO gas preparation and oxidation product reduction stage, high-purity CO2 gas is continuously introduced into the oxygen-saturated iron-based melt through the bottom blowing element placed at the bottom of the sealed gasifier. After dust removal and heat exchange, it is introduced into the gas separation device to obtain high-purity CO gas and high-purity CO2 gas respectively. CO gas enters the CO gas storage tank and CO2 gas enters the CO2 gas storage tank. At the same time, the positive terminal of the external DC power supply is inserted into the slag and the negative terminal of the external DC power supply is inserted into the iron-based melt. The external DC power supply is turned on to reduce FeO in the oxidation product slag to liquid iron and oxygen. The liquid iron returns to the iron-based melt, completing the process of CO2 deoxidation to produce CO gas without carbon.

[0016] (4) Entering the furnace charge replenishment stage, after the system has run for one cycle, the bottom blowing gas of the sealed gasifier is switched to high-purity argon, and the pneumatic three-way ball valve is set to the venting mode. The gaseous products are discharged into the atmospheric environment. Electrolytic pure iron and high-purity magnesium oxide are added to the molten pool through the silo. After the newly added iron-based raw materials and slag in the molten pool are completely melted, the stage of CO gas preparation and oxidation product reduction will be restored.

[0017] Furthermore, in step (2), the power of the heating element of the sealed gasifier 1 is set to 3000kW-50000kW, and the gauge pressure of the high-purity CO2 gas blown in from the bottom blowing element is 0.2-0.4MPa, and the flow rate is 10-200Nm³. 3 / h.

[0018] Furthermore, in step (3), the current range of the external DC power supply is set to 1-300kA and the voltage to 10-1000V.

[0019] Furthermore, in step (3), the power of the heating element of the sealed gasifier is set to 1000-20000kW, and the gauge pressure of the high-purity CO2 gas blown in from the bottom blowing element is 0.3-0.6MPa, and the flow rate is 20-500Nm³. 3 / h high-purity CO2 gas.

[0020] Furthermore, in step (4), the high-purity argon gas blown in from the bottom-blowing element has a gauge pressure of 0.2-0.4 MPa and a flow rate of 10-200 Nm³. 3 / h.

[0021] Furthermore, the electromagnetic induction heating coil is installed outside the furnace body of the sealed gasifier, the hopper is installed on the upper part of the sealed gasifier, and the external DC power supply electrolysis system is installed on the upper part of the sealed gasifier.

[0022] Furthermore, the steam generated by the heat exchanger is transported to the steam inlet of the gas separation unit via the nineteenth pipe for the regeneration and separation of the adsorbed gas.

[0023] The beneficial effects of this invention include:

[0024] (1) The high-concentration CO2 gas obtained by enriching CO2 in the tail gas generated during the production process of the iron and steel industry or the chemical industry can be used as the reaction gas to react with oxygen-saturated iron-based melt to generate high-concentration tail gas (CO gas volume fraction greater than 85%), thus realizing the consumption of CO2 gas and the efficient preparation of CO gas, an important chemical raw material.

[0025] (2) The process described in this invention uses a high-temperature molten pool of 1600-1800℃ as the reaction environment, which can effectively break through the energy barrier of CO2 decomposition. At the same time, the reaction rate is high and stable, and it does not require a large amount of expensive catalysts in the traditional chemical CO2 reduction process. The process is simple, low-cost and has high preparation efficiency.

[0026] (3) A new method for producing CO from CO without carbon by carbon-free deoxidation using iron element as oxygen transfer medium in oxygen-saturated iron-based melt is based on the deoxidation method of CO2 coupled with an external electric field in high-oxidation iron slag, which changes the traditional CO2 resource utilization method of "reducing carbon with carbon" in the iron and steel smelting process.

[0027] (4) The electrical energy used by the equipment described in this invention is generated by photovoltaic power generation, wind power generation, hydropower generation or nuclear power generation devices, realizing the "electricity-energy" conversion of green electricity and CO gas;

[0028] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of a system for producing CO gas using carbon-free deoxygenation of CO2, according to a preferred embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of a closed gasifier in a preferred embodiment of the present invention;

[0031] Figure 3 yes Figure 2 A magnified view of a portion of point A in the middle. Detailed Implementation

[0032] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0033] 7. For example Figure 1As shown, a system for producing CO gas using carbon-free deoxygenation of CO2 according to the present invention includes a closed gasifier 1. The gaseous products generated by the closed gasifier 1 are connected to a gaseous product dust removal device 3 via pipe P1. The purified gaseous products enter the hot fluid inlet of a heat exchanger 4 via pipe P2. The cooled gaseous products are connected to a gaseous composition detection device 5 via pipe P3, and then connected to a booster 61 via pipe P4. The boosted gaseous products are connected to a pneumatic three-way ball valve 7 via pipe P5. One outlet of the pneumatic three-way ball valve 7 is connected to a gas separation device 8 via pipe P6, and the other outlet of the pneumatic three-way ball valve 7 is used for venting. The high-purity CO produced by the gas separation device 8... Gas is introduced into the inlet of booster 62 via pipeline P7. After being pressurized, high-purity CO gas is transported through pipeline P8 and stored in CO gas storage tank 9. High-purity CO2 gas produced by gas separation device 8 is connected to shut-off valve 101 via pipeline P9, and then introduced into the inlet of booster 63 via pipeline P10. After being pressurized, high-purity CO2 gas is transported through pipeline P11 and stored in CO2 gas storage tank 11. External high-purity CO2 gas is connected to shut-off valve 102 via pipeline P12, and then transported to CO2 gas storage tank 11 via pipeline P13. High-purity CO2 gas in CO2 gas storage tank 11 is introduced into the cold fluid inlet of heat exchanger 4 via pipeline P14. After heat exchange, it is connected to shut-off valve 103 via pipeline P15. The gas is then connected via pipeline P16 to pressure and flow regulating valve P17. After pressure and flow regulation, the high-purity CO2 gas is connected via pipeline P17 to the inlet of CO2 gas flow meter. After flow measurement, it is connected via pipeline P18 to the bottom blowing element 14 installed at the bottom of the closed gasifier 1. The water vapor generated by heat exchanger 4 is transported via pipeline P19 to the water vapor inlet of gas separator 8 for the regeneration and separation of adsorbed gas. Electromagnetic induction heating coil 15 is installed outside the furnace body of closed gasifier 1. The negative terminal 16 and positive terminal 17 of the external DC power supply are both installed on the upper part of closed gasifier 1. The positive terminal sealing tube 18 is installed outside the positive terminal of the external DC power supply and is connected to the induced draft fan or vacuum pump 64 and shut-off valve 104 via pipeline P19. The energy required for CO2 decomposition endothermic heat and slag DC electrolytic reduction heat consumption is generated by photovoltaic power generation.

[0034] The method for preparing CO gas using CO2 according to the present invention includes the following steps:

[0035] In the oxygen-saturated iron-based melt preparation stage, 10t of electrolytic pure iron is charged into the closed gasifier 1 as the molten pool metallic phase raw material, and 0.5t of high-purity magnesium oxide is added as a slag conditioner. The heating element power of the closed gasifier 1 is set to 6000kW, and the metallic phase raw material 19 is melted by electricity, raising the molten pool temperature to 1600℃. External high-purity CO2 gas is stored in the CO2 gas storage tank 11 and connected to the inlet of the bottom blowing element 14 via heat exchanger 4, pneumatic ball valve 103, pressure and flow regulating valve 12, and CO2 gas flow meter 13. A gauge pressure of 0.2MPa and a flow rate of 20Nm³ are continuously introduced from the bottom blowing element 14 located at the bottom of the closed gasifier 1. 3 The high-purity CO2 gas at a rate of / h is used to detect the volume fraction of CO gas and CO2 gas in the gas phase after dust removal and heat exchange during the melting process. After 2 hours, when the volume fraction of CO gas in the gas phase reaches more than 85%, the oxygen-saturated iron-based melt preparation stage is completed.

[0036] Entering the CO gas preparation and oxidation product reduction stage, the heating element power of the closed gasifier 1 is set to 2000kW. A bottom-blowing element 14, located at the bottom of the closed gasifier 1, continuously introduces a gas into the oxygen-saturated iron-based melt at a gauge pressure of 0.3MPa and a flow rate of 50Nm³. 3 High-purity CO2 gas is produced per hour. Simultaneously, the negative electrode 16 of the external DC power supply electrolysis system, located above the sealed gasifier, is lowered into the iron-based melt, and the positive electrode 17 is lowered into the slag. The voltage is set to 200V and the current is set to 20kA. The volume fraction of CO gas in the gas phase product is 85.75%, and the volume fraction of CO2 gas is 14.25%. After dust removal and heat exchange, the gas is introduced into the gas separation device 8 to obtain high-purity CO gas and high-purity CO2 gas respectively. The CO gas enters the CO gas storage tank 9, and the CO2 gas enters the CO2 gas storage tank 11.

[0037] During the 72nd hour of system operation, the bottom-blowing gas in the closed gasifier 1 was switched to high-purity argon, with a gauge pressure of 0.2 MPa and a flow rate of 20 Nm³. 3 / h, and set the pneumatic three-way ball valve 7 to the venting mode, so that the gaseous products are discharged into the atmosphere. Add 50kg of high-purity magnesium oxide and 100kg of electrolytic pure iron to the molten pool through the hopper 2 installed on the top of the sealed gasifier. After 15 minutes, when the newly added raw materials in the molten pool have completely melted, switch the production process to the CO gas preparation and oxidation product reduction stage.

[0038] In this embodiment, the equipment operates for 300 days, can process approximately 600 tons of CO2 gas annually, and produce approximately 308,700 Nm³ of CO gas. 3 .

[0039] Unlike existing technologies that use carbon raw materials such as graphite powder as reducing agents to reduce FeO, a deoxidation product in the slag phase, this invention uses an external electric field to regenerate the iron oxide slag, thus breaking away from the traditional "carbon reduction with carbon" model. Although it requires electricity, the electricity can come from clean energy sources such as hydropower, wind power, and nuclear power, achieving carbon-free deoxidation.

[0040] like Figure 2 As shown, the present invention further includes a positive electrode sealing tube 18 outside the positive electrode 17, which is connected to a vacuum pump 64. When the positive electrode 17 descends into the molten slag 20, the vacuum pump 64 is simultaneously activated. On the one hand, it discharges the oxygen generated at the positive electrode, reducing the oxygen partial pressure and accelerating the reaction rate. On the other hand, it creates a certain degree of vacuum inside the positive electrode sealing tube 18, causing some of the liquid slag phase 20 to be drawn into the positive electrode sealing tube 18, increasing the contact area with the positive electrode 17 and improving the electrolysis efficiency.

[0041] like Figure 3 As shown, the bottom of the positive electrode sealing tube 18 of the present invention has a porous section 22. The iron-based melt 19 and slag 20 outside the porous section 22 can enter the positive electrode sealing tube 18 through the porous section 22. In this way, even if the depth of the positive electrode sealing tube 18 exceeds the iron-slag two-phase boundary line 21 when it descends, and some melt 19 enters the positive electrode sealing tube 18, it will fall because its density is greater than that of the slag phase. Therefore, the control of the descent depth of the positive electrode sealing tube 18 can have a certain degree of tolerance, reducing the requirement for precise control of the descent depth of the positive electrode sealing tube 18.

[0042] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A system for producing CO gas using carbon-free deoxygenation of CO2, characterized in that, The closed gas generator, the electromagnetic induction heating coil, and the external DC power electrolysis system are included. The gas phase product generated by the closed gas generator is connected to the gas phase product dust removal device through the first pipeline. The purified gas phase product enters the heat fluid inlet of the heat exchanger through the second pipeline. The cooled gas phase product is connected to the gas phase component detection device through the third pipeline. The gas phase product is connected to the first supercharger through the fourth pipeline. The pressurized gas phase product is connected to the pneumatic three-way ball valve through the fifth pipeline. The first outlet of the pneumatic three-way ball valve is connected to the gas separation device through the sixth pipeline. The second outlet of the pneumatic three-way ball valve is used for emptying. The high-purity CO gas produced by the gas separation device is connected to the inlet of the second supercharger through the seventh pipeline. The high-purity CO gas is transported and stored in the CO gas storage tank through the eighth pipeline after being pressurized. The high-purity CO2 gas produced by the gas separation device is connected to the first stop valve through the ninth pipeline. The high-purity CO2 gas is transported to the CO2 gas storage tank through the thirteenth pipeline after being pressurized. The high-purity CO2 gas in the CO2 gas storage tank is connected to the cold fluid inlet of the heat exchanger through the fourteenth pipeline. The high-purity CO2 gas is connected to the third stop valve through the fifteenth pipeline after being heated. The high-purity CO2 gas is connected to the pressure flow regulating valve through the sixteenth pipeline. The high-purity CO2 gas is connected to the CO2 gas flow meter inlet through the seventeenth pipeline after being regulated. The high-purity CO2 gas is connected to the bottom blowing element installed at the bottom of the closed gas generator through the eighteenth pipeline after being measured. The positive electrode of the external DC power electrolysis system is further provided with a positive electrode sealing tube. The positive electrode sealing tube is connected to the vacuum pump. When the positive electrode is lowered into the slag, the vacuum pump is started synchronously. On the one hand, the oxygen generated by the positive electrode is discharged to reduce the oxygen partial pressure. On the other hand, the vacuum degree is generated in the positive electrode sealing tube, so that part of the liquid slag phase is sucked into the positive electrode sealing tube to increase the contact area with the positive electrode. The bottom of the positive electrode sealing tube is provided with a porous section. The iron-based melt and slag outside the porous section can enter the positive electrode sealing tube through the porous section. The iron-based melt entering the positive electrode sealing tube falls by itself due to the greater density than the slag phase.

2. The system for producing CO gas using CO2 carbon-free deoxygenation according to claim 1, wherein, The tonnage of the closed gas generator is 5t to 100t. The electromagnetic induction heating coil is installed outside the furnace body of the closed gas generator. The external DC power electrolysis system is installed on the upper part of the closed gas generator.

3. The system for producing CO gas using CO2 carbon-free deoxidation according to claim 1, wherein, The bunker installed on the upper part of the closed gas generator is further included.

4. The system for producing CO gas using CO2 carbon-free deoxygenation according to claim 1, wherein, The water vapor generated by the heat exchanger is transported to the water vapor inlet of the gas separation device through the nineteenth pipeline for the regeneration separation of the adsorbed gas.

5. The system for producing CO gas using CO2 carbon-free deoxygenation according to claim 1, wherein, The energy required for the heat absorption of CO2 decomposition and the direct current electrolysis reduction of slag is generated by photovoltaic, wind power, hydroelectric or nuclear power generation devices.

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