System for reducing carbon dioxide emission in coke production process

Abstract

The utility model relates to a system for reducing carbon dioxide emission in a coke production process, after coke oven flue gas is desulfurized and denitrated, CO2 absorbed and desorbed from the coke oven flue gas and hydrogen prepared by electrolyzed water are synthesized into methane, heat released in the methane synthesis process exchanges heat to generate water vapor, the water vapor is recycled, the synthesized methane is supplied to a coke oven again for heating, and the carbon dioxide emission is reduced. The device has the beneficial effects that two-way circulation is realized, the energy is fully utilized, the emission of CO2 in the coke oven flue gas to the atmosphere can be effectively reduced, the CO2 in the coke oven flue gas can be captured and converted into methane fuel, the methane fuel is used as heating fuel of the coke oven, the CO2 generated by combustion of the coke oven is not discharged, and the energy is saved. Therefore, cyclic utilization of CO2 is realized, and green development is realized.

Description

Technical Field

[0001] This utility model relates to the fields of coking and environmental protection technology, and in particular to a system for reducing carbon dioxide emissions during coke production. Background Technology

[0002] Carbon dioxide is one of the major greenhouse gases, and its emissions contribute to rising Earth's surface temperatures, leading to global warming. This change results in more frequent extreme weather events, such as floods, droughts, and storms. The steel industry, as the largest emitter of carbon dioxide, currently faces enormous pressure and challenges in reducing its carbon footprint.

[0003] Most steel mills use a mixture of blast furnace gas (also known as lean coal gas) and coke oven gas as fuel during coking production. Therefore, the flue gas emitted during coking contains large amounts of toxic gases and carbon dioxide. Current chemical pollutant emission standards only apply to NOx in coke oven flue gas. X Emissions of pollutants such as SO2 are limited, and currently most companies only target NO in flue gas. X They focus on controlling SO2 emissions, but pay little attention to CO2 emissions from coke oven flue gas.

[0004] Chinese invention patent CN110141947A discloses a "coke oven flue gas carbon dioxide emission reduction process and system" that uses ammonia water to absorb CO2 from coke oven flue gas. After CO2 removal, the gas is discharged through the coke oven flue gas outlet. The ammonium bicarbonate solution generated by the reaction of ammonia water and CO2 enters the CO2 desorption system. In the CO2 desorption system, the ammonium bicarbonate solution reacts with sulfuric acid in the reactor to generate ammonium sulfate, which dissolves in the aqueous solution, while CO2 gas is released. The released CO2 gas enters the carbonization chamber of the high-temperature coal dry distillation system and reacts with the coal and coke materials in the carbonization chamber. The generated CO enters the subsequent coal gas collection and purification system along with the coal gas released during the dry distillation process. This emission reduction method consumes coke during the CO generation process, affecting coke production and is detrimental to coking production. Utility Model Content

[0005] To overcome the shortcomings of existing technologies, this utility model provides a system for reducing carbon dioxide emissions during coke production. After desulfurization and denitrification of coke oven flue gas, the CO2 released is absorbed and hydrogen produced by water electrolysis is used to synthesize methane. The heat released during methane synthesis is used to generate water vapor for reuse. The synthesized methane is then used to heat the coke oven again. The separated water after methane synthesis is used again for water electrolysis to produce hydrogen. This two-way cycle fully utilizes energy and effectively reduces CO2 emissions from coke oven flue gas into the atmosphere. Furthermore, it can capture CO2 in coke oven flue gas and convert it into methane fuel, which is used as heating fuel for the coke oven. The CO2 produced by coke oven combustion is not emitted externally, thus achieving CO2 recycling and green development.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A system for reducing carbon dioxide emissions during coke production includes a coke oven heating system, a flue gas desulfurization and denitrification system, a CO2 absorption and desorption system, a methane synthesis system, a methane storage system, a water electrolysis hydrogen production system, a hydrogen storage system, a methane storage system, and a water separation and purification system. The flue gas outlet of the coke oven heating system is sequentially connected to the flue gas desulfurization and denitrification system and the CO2 absorption and desorption system via pipelines. The water electrolysis hydrogen production system is connected to the hydrogen storage system via pipelines. The CO2 outlet of the CO2 absorption and desorption system and the H2 outlet of the hydrogen storage system are respectively connected to the methane synthesis system via pipelines. The methane outlet of the methane synthesis system is connected to the coke oven heating system via the methane storage system. The water separation outlet of the methane synthesis system is connected to the water electrolysis hydrogen production system via the water separation and purification system.

[0008] The methane synthesis system includes a methanation inlet heat exchanger, a methanation reactor, a waste heat boiler, a circulating water heat exchanger, and a gas-liquid separator. The methanation inlet heat exchanger is connected sequentially to the methanation reactor, the waste heat boiler, the circulating water heat exchanger, and the gas-liquid separator via pipelines. The gas inlet of the methanation inlet heat exchanger is connected to the CO2 outlet of the CO2 absorption and desorption system and the H2 outlet of the hydrogen storage system. The methane outlet of the gas-liquid separator is connected to the methane storage system via a pipeline, and the separated water outlet is connected to the separated water purification system via a pipeline.

[0009] Furthermore, the system for reducing carbon dioxide emissions during coke production also includes a wind power / photovoltaic power generation system and an energy storage system. The power supply outlet of the wind power / photovoltaic power generation system is divided into two paths: one path connects to the power supply inlet of the water electrolysis hydrogen production system, and the other path connects to the power supply inlet of the energy storage system. The power supply outlet of the energy storage system is connected to the power supply inlet of the water electrolysis hydrogen production system.

[0010] Furthermore, the remaining flue gas from the CO2 absorption and desorption system is discharged through a chimney after passing through a dust collector.

[0011] Furthermore, the hydrogen storage system is equipped with hydrogen balloon tanks to buffer and store hydrogen from the water electrolysis hydrogen production system.

[0012] Furthermore, the methane storage system is equipped with methane spherical tanks to buffer and store methane from the methane synthesis system.

[0013] Furthermore, the chemical reaction formula in the methane chemical reactor is: CO2 + 4H2 → CH4 + 2H2O.

[0014] Furthermore, the water purification system described herein uses reverse osmosis + ion exchange to purify the separated water.

[0015] Compared with the prior art, the beneficial effects of this utility model are:

[0016] 1) Green electricity is used to produce green hydrogen, which is coupled with carbon dioxide separated from coke oven flue gas to produce methane. The methane is then used as heating fuel for the coke oven, resulting in green and sustainable methane production with no excess pollution emissions, thus improving the level of green coking production.

[0017] 2) The CO2 after methane combustion can be captured and reacted with green hydrogen produced by green electricity to generate methane. The methane is then sent back to the coke oven for heating, thus recycling CO2 and improving the CO2 reuse rate.

[0018] 3) The CO2 removal rate in coke oven flue gas is ≥85%, and the CO2 concentration in the remaining flue gas can be as low as 50 PPM. CO2 is reused to synthesize methane for coke oven heating, significantly reducing CO2 emissions. The CO2 in the emitted coke oven flue gas is reduced, environmental pollution is reduced, and the ecological environment around coke oven production is improved.

[0019] 4) By eliminating the use of coke oven gas as heating fuel, more coke oven gas can be used to produce chemical products such as hydrogen, LNG, synthetic ammonia, methane, methanol, gasoline, blast furnace injection steelmaking, and power generation, thus saving coke oven fuel resources, reducing coke oven fuel costs, increasing the amount of coke oven gas by-products, and increasing by-product revenue.

[0020] 5) The CO2 conversion rate of the methanation reaction can reach over 90%. The high CO2 conversion rate improves utilization, generates fewer by-products, and results in high methane purity. This leads to high thermal energy utilization for coke oven production and high coke production rate.

[0021] 6) The heat released during the reaction of CO2 and hydrogen to produce methane is recovered and reused, so there is no heat loss and the energy resource utilization rate is high. The generated methane is used for coke oven production, and the water generated in the reaction is reused for hydrogen production. This two-way recycling makes more efficient use of resources and saves coke production resources and costs. Attached Figure Description

[0022] Figure 1 This is a system flow diagram of reducing carbon dioxide emissions during coke production, as described in this utility model.

[0023] Figure 2 This is a flowchart of the methane synthesis system described in this utility model.

[0024] Figure 3 This is a flowchart of the power supply system of the wind power / photovoltaic power generation system described in this utility model. Detailed Implementation

[0025] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings:

[0026] like Figures 1-3 As shown, a system for reducing carbon dioxide emissions during coke production includes a coke oven heating system, a flue gas desulfurization and denitrification system, a CO2 absorption and desorption system, a methane synthesis system, a methane storage system, a water electrolysis hydrogen production system, a hydrogen storage system, a methane storage system, and a water separation and purification system. The flue gas outlet of the coke oven heating system is sequentially connected to the flue gas desulfurization and denitrification system and the CO2 absorption and desorption system via pipelines. The water electrolysis hydrogen production system is connected to the hydrogen storage system via pipelines. The CO2 outlet of the CO2 absorption and desorption system and the H2 outlet of the hydrogen storage system are respectively connected to the methane synthesis system via pipelines. The methane outlet of the methane synthesis system is connected to the coke oven heating system via the methane storage system. The water separation outlet of the methane synthesis system is connected to the water electrolysis hydrogen production system via the water separation and purification system. The coke oven flue gas generated after combustion in the coke oven heating system passes through the flue gas desulfurization and denitrification system to remove NO from the coke oven flue gas. x After SO2 removal, the gas enters the CO2 absorption and desorption system to separate CO2 from the coke oven flue gas. The separated CO2 enters the methane synthesis system through a carbon dioxide pipeline. The remaining flue gas after CO2 removal is discharged through a chimney after dust removal by a dust collector. The water electrolysis hydrogen production system produces hydrogen by electrolyzing water in an electrolyzer and then purifies the hydrogen before sending it to the hydrogen storage system. The hydrogen storage system buffers and temporarily stores the purified hydrogen from the water electrolysis hydrogen production system before gently sending it to the methane synthesis system. The methane synthesis system reacts the received CO2 and hydrogen to produce methane and separated water. The produced methane is sent to the methane storage system, which buffers and stores the methane from the methane synthesis system before sending it to the coke oven heating system to produce coke. The separated water produced is sent to the separated water purification system, which purifies the separated water using a combination of reverse osmosis and ion exchange, a physical and chemical process. The purified separated water is then sent to the water electrolysis hydrogen production system to produce hydrogen.

[0027] The methane synthesis system includes a methanation inlet heat exchanger, a methanation reactor, a waste heat boiler, a circulating water heat exchanger, and a gas-liquid separator. The methanation inlet heat exchanger is connected sequentially to the methanation reactor, waste heat boiler, circulating water heat exchanger, and gas-liquid separator via pipelines. The gas inlet of the methanation inlet heat exchanger is connected to the CO2 outlet of the CO2 absorption and desorption system and the H2 outlet of the hydrogen storage system. The methane outlet of the gas-liquid separator is connected to the methane storage system via a pipeline, and the separated water outlet is connected to the separated water purification system via a pipeline. Hydrogen from the hydrogen storage system and CO2 from the CO2 absorption and desorption system are mixed and heated in the methanation inlet heat exchanger. The heated mixed gas then enters the methanation reactor. The methanation reactor operates at a temperature between 200 and 300°C and a pressure of 3 MPa. A chemical reaction occurs under the catalysis of Ni + Al₂O₃, with the reaction formula CO₂ + 4H₂ → CH₄ + 2H₂O, producing water and methane. The methane production reaction in the methanation reactor is exothermic, and the resulting mixture of methane and water carries a large amount of heat. The methane and water are then passed into a waste heat boiler for heat exchange. The waste heat boiler generates steam, which is then recovered and reused. The cooled methane and water mixture enters a circulating water heat exchanger for further cooling. The further cooled methane and water mixture then enters a gas-liquid separator for separation. The separated methane is sent to a methane storage system, and the separated water is sent to a water purification system.

[0028] like Figure 3 As shown, the system for reducing carbon dioxide emissions during coke production further includes a wind power / photovoltaic power generation system and an energy storage system. The power supply outlet of the wind power / photovoltaic power generation system is divided into two paths: one path connects to the power supply inlet of the water electrolysis hydrogen production system, and the other path connects to the power supply inlet of the energy storage system. The power supply outlet of the energy storage system is connected to the power supply inlet of the water electrolysis hydrogen production system. The wind power / photovoltaic power generation system converts wind energy or solar energy into electrical energy. A portion of the generated electrical energy is sent to the water electrolysis hydrogen production system for hydrogen production, and the other portion is sent to the energy storage system for storage. When the amount of electricity directly supplied to the water electrolysis hydrogen production system by the wind power / photovoltaic power generation system is less than a set value, the electrical energy stored in the energy storage system is released and sent to the water electrolysis hydrogen production system, thereby achieving continuous and stable operation of the water electrolysis hydrogen production system.

[0029] Furthermore, the remaining flue gas from the CO2 absorption and desorption system is discharged through a chimney after passing through a dust collector.

[0030] Furthermore, the hydrogen storage system is equipped with hydrogen balloon tanks to buffer and store hydrogen from the water electrolysis hydrogen production system.

[0031] Furthermore, the methane storage system is equipped with methane spherical tanks to buffer and store methane from the methane synthesis system.

[0032] Furthermore, the chemical reaction formula in the methane chemical reactor is: CO2 + 4H2 → CH4 + 2H2O.

[0033] Furthermore, the water purification system described herein uses reverse osmosis + ion exchange to purify the separated water.

[0034] This invention captures CO2 from coke oven flue gas and converts it into methane fuel. Methane fuel is a low-carbon fuel. By using methane as fuel for the coke oven heating system, the CO2 in the generated flue gas is recycled, which can significantly reduce carbon emissions in the coking process and thus effectively reduce CO2 emissions from coke oven flue gas. The water generated during the methane production process is recycled for hydrogen production. This two-way recycling system results in high resource utilization and full utilization of resources.

[0035] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A system for reducing carbon dioxide emissions in a coke production process, comprising a coke oven heating system, a flue gas desulfurization and denitrification system, a CO2 absorption and desorption system, a methane synthesis system, a methane storage system, an electrolytic water hydrogen production system, a hydrogen storage system, a methane storage system, and a separation water purification system, characterized in that, The coke heating system flue gas outlet is connected with the flue gas desulfurization and denitrification system and the CO2 absorption and resolution system in sequence through pipelines; the electrolytic water hydrogen production system is connected with the hydrogen storage system through a pipeline; the CO2 outlet of the CO2 absorption and resolution system and the H2 outlet of the hydrogen storage system are connected with the methane synthesis system through pipelines respectively; the methane outlet of the methane synthesis system is connected with the coke heating system through a methane storage system; the separated water outlet of the methane synthesis system is connected with the electrolytic water hydrogen production system through a separated water purification system; The methane synthesis system comprises a methanation inlet tower heat exchanger, a methanation reactor, a waste heat boiler, a circulating water heat exchanger and a gas-liquid separator; the methanation inlet tower heat exchanger is connected with the methanation reactor, the waste heat boiler, the circulating water heat exchanger and the gas-liquid separator in sequence through pipelines; the gas inlet of the methanation inlet tower heat exchanger is connected with the CO2 outlet of the CO2 absorption and resolution system and the H2 outlet of the hydrogen storage system; the methane outlet of the gas-liquid separator is connected with the methane storage system through a pipeline; and the separated water outlet is connected with the separated water purification system through a pipeline.

2. A system for reducing carbon dioxide emissions in a coke production process according to claim 1, characterized in that, The system for reducing carbon dioxide emission in the coke production process further comprises a wind power / photovoltaic power generation system and an energy storage system; the power supply outlet of the wind power / photovoltaic power generation system is divided into two paths, one of which is connected with the power supply inlet of the electrolytic water hydrogen production system, and the other of which is connected with the power supply inlet of the energy storage system; and the power supply outlet of the energy storage system is connected with the power supply inlet of the electrolytic water hydrogen production system.

3. A system for reducing carbon dioxide emissions in a coke production process according to claim 1, characterized in that, The remaining flue gas of the CO2 absorption and resolution system is discharged through a chimney after passing through a dust remover.

4. The system for reducing carbon dioxide emissions in a coke production process of claim 1, wherein, The hydrogen storage system is provided with a hydrogen ball tank for buffering and storing hydrogen from the electrolytic water hydrogen production system.

5. The system for reducing carbon dioxide emissions in a coke production process of claim 1, wherein, The methane storage system is provided with a methane ball tank for buffering and storing methane from the methane synthesis system.

6. The system for reducing carbon dioxide emissions in a coke production process of claim 1, wherein, The chemical reaction formula in the methanation reactor is: CO2+4H2→CH4+2H2O.

7. The system for reducing carbon dioxide emissions in a coke production process of claim 1, wherein, The separated water purification system adopts reverse osmosis+ion exchange to purify separated water.

Images