Comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas

Abstract

The utility model discloses a comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas. Comprising a purification and desulfurization device, a CO2 separation and purification device, a first pressure swing adsorption device, a purification and separation device, a methanation device, a second pressure swing adsorption device, a dry reforming reaction device, a third pressure swing adsorption device, a methanol synthesis device, a rectification device, a compressor, a first gas mixing device, a second gas mixing device and a blast furnace. The blast furnace gas pipe network is sequentially communicated with the purification and desulfurization device and the CO2 separation and purification device through pipelines, a CO2-poor gas outlet of the CO2 separation and purification device is communicated with an inlet of the first pressure swing adsorption device, a CO2-rich gas outlet of the CO2 separation and purification device is communicated with the first gas mixing device, and a CO-rich gas outlet of the first pressure swing adsorption device is communicated with a gas inlet of the blast furnace through the second gas mixing device. According to the system, CO2 emission is reduced, and meanwhile, effective components of coal gas are recycled and efficiently utilized.

Description

Technical Field

[0001] The utility model relates to the field of coal gas resource utilization, in particular to a comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas. Background Art

[0002] The steel industry is a major CO2 emitter, accounting for about 15% of the country's carbon emissions, of which by-product gas (blast furnace gas, converter gas, coke oven gas) is the main source of carbon emissions. At present, using it through power generation, combustion and other means not only causes waste of resources, but also pollutes the environment. Therefore, improving the utilization rate of gas resources and reducing carbon emissions have become urgent needs for the sustainable development of the steel industry.

[0003] The steel and petrochemical co-production not only enables efficient utilization of by-product gas from steel mills, but also promotes the diversified supply of chemical raw materials. Most importantly, it can fix the carbon elements emitted by the steel industry and achieve the goal of carbon reduction. The development of steel and petrochemical co-production in the steel industry focuses on separating and purifying the effective components (H2, CO, CO2, CH4, etc.) in the by-product gas of steel mills as raw materials, and synthesizing chemical products such as methanol, ethanol, ethylene glycol, urea, etc. Methanol is widely used as a chemical raw material and green fuel, and has a large market capacity. Separating and purifying CO2 and H2 from steel mill gas through steel and petrochemical co-production and synthesizing high-value methanol is an effective way to reduce carbon and increase efficiency.

[0004] The patent application with publication number CN116397062A provides a near-zero carbon emission blast furnace long-process tempering co-production process and system thereof, in which blast furnace gas is decarbonized by pressure swing adsorption to separate desorbed gas and decarbonized gas; desorbed gas is purified by liquefied distillation to obtain liquid carbon dioxide; part of the decarbonized gas is recycled to the blast furnace, and the other part is mixed with refined converter gas and coke oven gas converted by light hydrocarbons to separate CO+N2 and H2 logistics for synthesizing ethylene glycol. This process and system solidify "carbon" emissions into liquid carbon dioxide products through steel-coke fusion and tempering co-production; but CO2 is not directly fixed as a high-value product, and the subsequent CO2 treatment process is added.

[0005] The patent application with publication number CN116947619A provides a process and system for producing acetic acid by dry reforming and carbonylation synthesis of methane-rich gas. The method uses methane-rich gas and CO2 as raw materials, and obtains acetic acid products through dry reforming reaction, CO2 separation, CO separation, methanol synthesis, carbonylation synthesis and other processes. The process and system make full use of methane-rich gas to produce acetic acid, reducing the emission of greenhouse gas CO2 in the traditional acetic acid preparation process; however, the source of CO2 raw gas is unknown, the process flow is long, and no effective treatment is performed on steel plant coal gas. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas by circulating and efficiently utilizing various components of the gas.

[0007] In order to solve the above technical problems, the technical scheme adopted by the utility model is: including a purification and desulfurization device, a CO2 separation and purification device, a No. 1 pressure swing adsorption device, a purification and separation device, a methanation device, a No. 2 pressure swing adsorption device, a dry reforming reaction device, a No. 3 pressure swing adsorption device, a methanol synthesis device, a distillation device, a compressor, a No. 1 gas mixing device, a No. 2 gas mixing device and a blast furnace; the blast furnace gas pipeline network is connected to the purification and desulfurization device and the CO2 separation and purification device in sequence through a pipeline, the lean CO2 gas outlet of the CO2 separation and purification device is connected to the inlet of the No. 1 pressure swing adsorption device, and the rich CO2 gas outlet is connected to the No. 1 gas mixing device, and the No. 1 pressure swing adsorption device The CO-rich gas outlet of the device is connected to the gas inlet of the blast furnace through the No. 2 gas mixing device; the coke oven gas pipeline network is connected to the purification and separation device, the methanation device and the No. 2 pressure swing adsorption device in sequence through pipelines, the H2-rich gas outlet of the No. 2 pressure swing adsorption device is connected to the inlet of the No. 2 gas mixing device, and the methane-rich gas outlet is connected to the inlet of the No. 1 gas mixing device; the outlet of the No. 1 gas mixing device is connected to the dry reforming reaction device and the No. 3 pressure swing adsorption device in sequence, and the lean CO gas outlet of the No. 3 pressure swing adsorption device is connected to the methanol synthesis device and the distillation device in sequence; the CO-rich gas outlet of the No. 3 pressure swing adsorption device is connected to the inlet of the No. 2 gas mixing device; the compressor provides power.

[0008] Furthermore, a No. 3 gas mixing device is provided between the No. 3 pressure swing adsorption device and the methanol synthesis device; the purge gas outlet of the methanol synthesis device is connected to the inlet of the No. 3 gas mixing device.

[0009] Furthermore, the tail gas outlet of the No. 1 pressure swing adsorption device is connected to the gas pipeline network.

[0010] The beneficial effects of adopting the above technical scheme are as follows: the utility model uses CO2 in blast furnace gas and methane-rich gas obtained by methanation of coke oven gas as raw materials for dry reforming, and synthesizes methanol products after separating part of CO from the obtained synthesis gas, which solves the problem of large-scale emission of CO2 from blast furnace gas in steel plants and makes high-value utilization. The CO separated from blast furnace gas, the CO separated from synthesis gas, and the hydrogen-rich gas produced by methanation of coke oven gas described in the utility model are sprayed back into the blast furnace, realizing the efficient and cyclic utilization of each effective component of steel plant gas, the process flow is simple, and the carbon reduction of the blast furnace process is carried out from the source. While reducing CO2 emissions, the utility model realizes the efficient and cyclic utilization of each effective component of coal gas, improves the economic benefits of steel plants, and is of great significance to the realization of the "dual carbon" goal. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0012] Figure 1 It is a schematic diagram of the system structure of the utility model. DETAILED DESCRIPTION

[0013] Figure 1 As shown, the comprehensive utilization system of synthesizing methanol from blast furnace gas and coke oven gas comprises a purification and desulfurization device, a CO2 separation and purification device, a No. 1 pressure swing adsorption device, a purification and separation device, a methanation device, a No. 2 pressure swing adsorption device, a dry reforming reaction device, a No. 3 pressure swing adsorption device, a methanol synthesis device, a rectification device, a No. 1 gas mixing device, a No. 2 gas mixing device, a No. 3 gas mixing device, a blast furnace, a No. 1 compressor, a No. 2 compressor, a No. 3 compressor, a No. 4 compressor and a No. 5 compressor. The blast furnace gas pipeline network is connected to the inlet of the purification and desulfurization device through a pipeline, and the outlet of the purification and desulfurization device is connected to the inlet of the CO2 separation and purification device through the No. 1 compressor; the lean CO2 gas outlet of the CO2 separation and purification device is connected to the inlet of the No. 1 pressure swing adsorption device through the No. 2 compressor, the rich CO gas outlet of the No. 1 pressure swing adsorption device is connected to the inlet of the No. 2 gas mixing device, and the outlet of the No. 2 gas mixing device is connected to the gas inlet of the blast furnace; the rich CO2 gas outlet of the CO2 separation and purification device is connected to the No. 1 gas mixing device; the tail gas outlet of the No. 1 pressure swing adsorption device is connected to the gas pipeline network. After adopting such a structure, the blast furnace gas is purified and desulfurized by the purification and desulfurization device, and then the CO2 separation and purification device is used to obtain CO2-rich product gas and CO2-lean gas; the CO2-lean gas is subjected to CO separation and purification by the No. 1 pressure swing adsorption device to obtain 1# CO-rich product gas and carbon oxide-lean tail gas; the 1# CO-rich product gas is sent to the No. 2 mixing device and mixed with the following 2# CO-rich product gas and H2-rich gas, and then sent to the blast furnace for use as coal gas; the CO2-rich product gas is sent to the No. 1 mixing device; the carbon oxide-lean tail gas is sent to the gas pipeline network.

[0014] Figure 1As shown, the comprehensive utilization system of blast furnace gas and coke oven gas for synthesizing methanol, the coke oven gas pipeline network is connected to the inlet of the purification and separation device through a pipeline, the outlet of the purification and separation device is connected to the inlet of the methanation device through compressor No. 3, and the outlet of the methanation device is connected to the inlet of the No. 2 pressure swing adsorption device; the methane-rich gas outlet of the No. 2 pressure swing adsorption device is connected to the inlet of the No. 1 gas mixing device, the outlet of the No. 1 gas mixing device is connected to the inlet of the dry reforming reaction device through compressor No. 4, the outlet of the dry reforming reaction device is connected to the inlet of the No. 3 pressure swing adsorption device, the lean CO gas outlet of the No. 3 pressure swing adsorption device is connected to the inlet of the No. 3 gas mixing device, the outlet of the No. 3 gas mixing device is connected to the inlet of the methanol synthesis device through compressor No. 5, and the outlet of the methanol synthesis device is connected to the inlet of the distillation device; the relaxation gas outlet of the methanol synthesis device is connected to the inlet of the No. 3 gas mixing device; the H2-rich gas outlet of the No. 2 pressure swing adsorption device is connected to the inlet of the No. 2 gas mixing device; the CO-rich gas outlet of the No. 3 pressure swing adsorption device is connected to the inlet of the No. 2 gas mixing device. After adopting such a structure, the coke oven gas is purified and separated by the purification and separation device, then enters the methanation device for methanation reaction, and then enters the No. 2 pressure swing adsorption device to separate the gas to obtain methane-rich gas and H2-rich gas; the methane-rich gas is mixed with the above-mentioned CO2-rich product gas in the No. 1 gas mixing device, and then enters the dry reforming reaction device for dry reforming reaction to obtain synthesis gas; the synthesis gas is separated from part of CO by the No. 3 pressure swing adsorption device to obtain 2# CO-rich product gas and CO-lean product gas; the CO-lean product gas enters the methanol synthesis device to be synthesized into crude methanol, and the crude methanol enters the distillation device for distillation to obtain methanol product; the methanol purge gas generated by the methanol synthesis device returns to the No. 3 gas mixing device to be mixed with the CO-lean product gas, and methanol synthesis is carried out again; the H2-rich gas and 2# CO-rich product gas enter the No. 2 gas mixing device, and after being mixed with the above-mentioned 1# CO-rich product gas, they are sent to the blast furnace for use as coal gas.

[0015] Figure 1 As shown, the production process of the comprehensive utilization system of blast furnace gas and coke oven gas to synthesize methanol includes the following steps:

[0016] (1) After blast furnace gas is purified and desulfurized, CO2 is separated and purified to obtain CO2-rich product gas and CO2-lean gas; the CO2-lean gas is subjected to CO separation and purification to obtain 1# CO-rich product gas and carbon oxide-lean tail gas; the carbon oxide-lean tail gas is returned to the gas pipeline network for combustion and power generation;

[0017] The main components of the blast furnace gas are (vol): CO 20-30%, CO2 15-25%, CH4 0.4-1.5%, H21.5-3.5%, O2 0.2-1.0%, N2 46-60%. The blast furnace gas is purified and desulfurized to a sulfur content of <0.1ppm and an oxygen content of <300ppm. The CO2 content in the CO2-rich product gas is >85vol%, and the CO content in the 1# CO-rich product gas is >85vol%.

[0018] (2) After the coke oven gas is purified and separated, it is subjected to a methanogenic reaction, and then the gas is separated to obtain methane-rich gas and H2-rich gas;

[0019] The main components of the coke oven gas are (vol): H2 50-65%, CO 4-10%, CO2 1-6%, CH4 15-23%, O2-1%, N2 5-8%. The coke oven gas is purified and separated to a sulfur content of <0.1ppm and an oxygen content of <300ppm. The main reactions of the methanation reaction are: CO+3H2→CH4+H2O, CO2+4H2→CH4+2H2O; the methanation reaction conditions are: reaction temperature 500-700℃, pressure 1-4MPa. The separation adopts a combination of one or more of pressure swing adsorption separation, membrane separation and cryogenic separation. The CH4 content in the methane-rich gas is >85vol%; the main components of the H2-rich gas are (vol): H2>80%, CO<10ppm, CO2<20ppm, CH4 0.5-3%, O2<10ppm.

[0020] (3) The CO2-rich product gas and the methane-rich gas are subjected to dry reforming reaction to obtain synthesis gas; a portion of CO is separated from the synthesis gas to obtain 2# CO2-rich product gas and CO-lean product gas;

[0021] The main reaction of the dry reforming reaction is: CO2+CH4→2CO+2H2; the reaction conditions of the dry reforming reaction are: reaction temperature 600-1200°C, pressure 0.1-4MPa; the catalyst used in the dry reforming reaction includes: a combination of one or more of a platinum-based catalyst, a rhodium-based catalyst, a palladium-based catalyst, a ruthenium-based catalyst, a nickel-based catalyst and a copper-based catalyst; the CO2-rich product gas:methane-rich gas=1:0.5-5; the volume ratio of CO / H2 in the synthesis gas=0.2-5:1. The CO content in the 2# CO-rich product gas is>90vol%, and the hydrogen-carbon molar ratio in the CO-poor product gas is H / C=2-2.8:1.

[0022] (4) synthesizing methanol from the CO-depleted product gas to obtain a methanol product; the methanol purge gas generated by the methanol synthesis is returned and mixed with the CO-depleted product gas to perform methanol synthesis again;

[0023] The main reaction of the methanol synthesis is: CO+2H2→CH3OH; the reaction conditions of the methanol synthesis are: temperature 200-300°C, pressure 2-8MPa; the purity of the methanol product is >98%.

[0024] (5) The 1# CO-rich product gas, the 2# CO-rich product gas and the H2-rich gas are mixed and then sprayed back into the blast furnace for recycling.

[0025] Specific production example: The comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas is used for production.

[0026] Using blast furnace gas and coke oven gas from a steel company as raw materials:

[0027] The main components of blast furnace gas are: CO 26%, CO2 20%, CH4 0.75%, H2 2.1%, O2 0.43%, N2 49.2%; temperature 40℃, pressure 6000Pa(A), flow rate 111000Nm 3 / h;

[0028] The main components of coke oven gas are: H2 60%, CO 6%, CO2 2%, CH4 22%, O2 0.72%, N2 7.6%; temperature 40℃, pressure 6000Pa(A), flow rate 275000Nm 3 / h;

[0029] Plant scale: Annual production of 400,000 tons of methanol, plant operation time 8,000 hours / year.

[0030] like Figure 1 As shown, the specific steps include:

[0031] (1) Separation and purification of CO2 and CO from blast furnace gas:

[0032] The flow rate is 111000Nm 3 / h blast furnace gas is purified and desulfurized to remove sulfur and oxygen in the gas to a sulfur content of <0.1ppm and an oxygen content of <300ppm, and then enters the CO2 separation and purification device for organic amine circulation absorption. The blast furnace gas in the device is countercurrently contacted with N-methyldiethanolamine (MEDA-CO2) to absorb CO2 through mass transfer and chemical reaction, and then the pressure is reduced and heated for desorption to obtain a flow rate of 24000Nm 3 / h, CO2-rich product gas with a CO2 concentration of 91.1%; then transported to the No. 1 gas mixing device to mix with the methane-rich gas. The adsorbed gas produced by the CO2 separation and purification device enters the No. 1 pressure swing adsorption device for pressure swing adsorption to purify CO, and obtains a flow rate of 30000Nm 3 / h, 1# CO-rich product gas with CO concentration of 96.2%.

[0033] (2) Methanation of coke oven gas to obtain methane-rich gas and H2-rich gas:

[0034] The flow rate is 275000Nm 3 / h of coke oven gas is purified and separated to remove sulfur to less than 0.1ppm and oxygen to less than 300ppm; then it enters the methanation unit for reaction. Under the conditions of 650℃ and 2.0MPa, CO, CO2 and H2 in the unit are converted into methane under catalytic action; then it enters the No. 2 pressure swing adsorption unit for hydrogen extraction and gas separation, and obtains a flow rate of 70000Nm 3 / h, methane-rich gas with a CH4 concentration of 88.26%, and a flow rate of 205000Nm 3 / h, H2 rich gas with a H2 concentration of 81.05%.

[0035] (3) Dry reforming reaction to obtain synthesis gas:

[0036] The flow rate is 70000Nm 3 / h, methane-rich gas with a CH4 concentration of 88.26% and a flow rate of 24000Nm 3 / h, CO2-rich product gas with a CO2 concentration of 91.1% was mixed, and then dry reformed over a nickel-based catalyst at 800°C and 1.0MPa to obtain a flow rate of 170,000Nm 3 / h, CO and H2 concentrations are 49.0% and 49.0% respectively. The synthesis gas is sent to the No. 3 pressure swing adsorption unit for pressure swing adsorption to extract part of the CO, and the flow rate is 48000Nm 3 / h, 2# CO-rich product gas with a CO concentration of 90.45%, and a flow rate of 120000Nm 3 / h, CO and H2 concentrations are 33.0% and 66.0% respectively, and the CO-lean product gas is produced.

[0037] (4) Methanol synthesis:

[0038] The flow rate is 120000Nm 3 / h, CO and H2 concentrations of 33.0% and 66.0% respectively, under the conditions of 250℃ and 6MPa, methanol synthesis is carried out over a copper-based catalyst to produce crude methanol, and the synthesized crude methanol is pumped to a distillation unit to separate water to produce methanol products (purity 99%), with an output of 400,000 tons / year. The methanol purge gas produced by the methanol synthesis unit is returned to the methanol synthesis unit.

[0039] (5) Back-spraying blast furnace:

[0040] The flow rate is 30000Nm 3 / h, 1# CO-rich product gas with a CO concentration of 96.2%, and a flow rate of 48000Nm 3 / h, 2# CO-rich product gas with a CO concentration of 90.45%, and a flow rate of 205000Nm 3 / h, and H2-rich gas with a H2 concentration of 81.05% is mixed and sprayed back into the blast furnace.

[0041] (6) Exhaust gas treatment:

[0042] The carbon oxide-poor tail gas from blast furnace gas after CO and CO2 are removed is returned to the gas network for use as fuel gas in various processes of steel production and power generation equipment.

Claims

1. A comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas, characterized in that: It comprises a purification and desulfurization device, a CO2 separation and purification device, a No. 1 pressure swing adsorption device, a purification and separation device, a methanation device, a No. 2 pressure swing adsorption device, a dry reforming reaction device, a No. 3 pressure swing adsorption device, a methanol synthesis device, a distillation device, a compressor, a No. 1 gas mixing device, a No. 2 gas mixing device and a blast furnace; the blast furnace gas pipeline network is connected to the purification and desulfurization device and the CO2 separation and purification device in sequence through pipelines, the lean CO2 gas outlet of the CO2 separation and purification device is connected to the inlet of the No. 1 pressure swing adsorption device, the rich CO2 gas outlet is connected to the No. 1 gas mixing device, and the rich CO gas outlet of the No. 1 pressure swing adsorption device is connected to the No. 2 pressure swing adsorption device through the No. 3 pressure swing adsorption device. The gas mixing device is connected to the gas inlet of the blast furnace; the coke oven gas pipeline network is connected to the purification and separation device, the methanation device and the No. 2 pressure swing adsorption device in sequence through pipelines, the H2-rich gas outlet of the No. 2 pressure swing adsorption device is connected to the inlet of the No. 2 gas mixing device, and the methane-rich gas outlet is connected to the inlet of the No. 1 gas mixing device; the outlet of the No. 1 gas mixing device is connected to the dry reforming reaction device and the No. 3 pressure swing adsorption device in sequence, and the lean CO gas outlet of the No. 3 pressure swing adsorption device is connected to the methanol synthesis device and the distillation device in sequence; the CO-rich gas outlet of the No. 3 pressure swing adsorption device is connected to the inlet of the No. 2 gas mixing device; the compressor provides power.

2. The comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas according to claim 1, characterized in that: A No. 3 gas mixing device is also provided between the No. 3 pressure swing adsorption device and the methanol synthesis device; the purge gas outlet of the methanol synthesis device is connected to the inlet of the No. 3 gas mixing device.

3. A comprehensive utilization system for synthesizing methanol from blast furnace gas and coke oven gas according to claim 1 or 2, characterized in that: The tail gas outlet of the No. 1 pressure swing adsorption device is connected to the gas pipeline network.

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