A near-zero carbon emission blast furnace long-process tempering co-production process and system

Abstract

The present invention discloses a near-zero carbon emission blast furnace long-process steelmaking co-production process and system thereof, the process comprising the following steps: blast furnace gas is subjected to pressure swing adsorption decarbonization to separate desorbed gas and decarbonized gas; the desorbed gas is purified by liquefaction distillation to obtain liquid carbon dioxide; a portion of the decarbonized gas is recycled to the blast furnace, and the other portion is mixed with refined converter gas and coke oven gas converted to light hydrocarbons, and then washed with low-temperature methanol, subjected to temperature swing adsorption and two-stage pressure swing adsorption to separate CO+N2 and H2 streams for synthesizing ethylene glycol. The present invention, through the ideas and advantages of steel-coke fusion and steelmaking co-production, converts "carbon" from fuel into raw materials and solidifies it from emissions into products, taking a green, low-carbon, and efficient development path; it mainly utilizes oxygen blast furnace gas decarbonization self-circulation to reduce blast furnace ironmaking carbon emissions, and uses surplus decarbonized gas, coke oven gas, and converter gas as raw materials for manufacturing chemical products, achieving "carbon sequestration and emission reduction" and increasing value and efficiency, significantly reducing primary energy consumption from the source.

Description

Technical Field

[0001] The present invention relates to the technical field of steel smelting, and in particular to a blast furnace long-process steelmaking co-production process and a system thereof with near-zero carbon emission. Background Art

[0002] Currently, with regard to the comprehensive utilization of coal gas in steel enterprises, while specialized processes such as coke oven gas to hydrogen and LNG offer high added value, other methods of utilizing thermal energy, such as blast furnace gas, converter gas, or blast furnace gas, converter gas mixed with coke oven gas, as fuel gas, and CCPP power generation, generate relatively low added value. To enhance the comprehensive utilization value of coal gas in steel enterprises, researchers believe that fully utilizing the chemical energy of coal gas, re-blowing a portion of it as reducing gas into the blast furnace, can reduce the coke ratio and coal injection rate. This utilization method can not only effectively reduce blast furnace operating costs but also improve the efficiency of fossil energy utilization. The remaining excess coal gas can be used as a chemical feedstock to produce chemical products, forming a refined upstream and downstream processing chain and replacing coal-based chemical products on the market. This approach not only addresses the raw material and equipment cost-effectiveness requirements of coal chemical industry, but also enables the recycling and utilization of coal gas in steel enterprises, effectively reducing the country's total fossil fuel consumption and carbon emissions at the source, in line with national carbon reduction policies.

[0003] Methanol is a basic raw material and important solvent for a variety of organic products. Its upstream raw materials include coke oven gas and natural gas. Methanol has a wide range of downstream applications, primarily in energy and chemical products. my country consumes 70 to 80 million tons of methanol annually. Coal-based methanol currently accounts for 76% of my country's production, while coke oven gas-based methanol and natural gas-based methanol account for 17% and 7%, respectively.

[0004] Ethylene glycol (EG) is an important organic chemical raw material, widely used in the production of chemical products such as antifreeze, polyester fibers (polyurethane, polyethylene terephthalate), and nanomaterials. It offers promising domestic and international markets. Although my country's EG production capacity has grown by an average of approximately 10% annually in recent years, current domestic EG production falls far short of meeting growing market demand, with external dependence remaining above 60%. Due to my country's relatively scarce petroleum resources, the petroleum-based ethylene production route has certain limitations. Therefore, the coal-based EG production route, which utilizes my country's abundant coal resources, is in line with my country's energy structure and industrial development.

[0005] Research and analysis of coal-to-methanol and ethylene glycol processes have revealed that the coal route essentially utilizes synthesis gas to produce methanol and ethylene glycol, with the gasification phase accounting for over 30% of the overall energy consumption. Utilizing synthesis gas produced without coal gasification and employing CO2 hydrogenation to produce methanol and catalytic coupling hydrogenation technologies for ethylene glycol production can save on gasification process construction and equipment costs, such as gasifiers. This effectively reduces methanol and ethylene glycol production costs and fully utilizes renewable energy. Among the three types of coal gases used in steel plants, coke oven gas contains approximately 60% H2, converter gas contains approximately 60% CO, and oxygen blast furnace gas contains approximately 45% CO. These gases, after purification, can be combined into synthesis gas for methanol and ethylene glycol production, fully utilizing the chemical energy of the steel plant's coal gas resources.

[0006] Given this situation, how to comprehensively utilize blast furnace, converter, and coke oven gas to achieve high added value and reduce steel production costs has long been a key concern for steel companies. However, how to efficiently utilize gas resources while significantly reducing carbon emissions remains a challenge that needs to be addressed. Summary of the Invention

[0007] In response to the problem of low gas utilization efficiency in existing steel enterprises, the present invention provides a near-zero carbon emission blast furnace long-process steelmaking co-production process and system. First, it solves the problems of high energy consumption and low recovery rate in producing decarbonized gas from blast furnace gas. Second, it solves the problem of low purity of captured carbon dioxide products and inconvenience in transportation. Third, it solves the problem of low utilization efficiency and increased carbon emissions of blast furnace gas, converter gas and coke oven gas. Fourth, it provides a lower-cost path for the preparation of chemical products ethylene glycol and methanol.

[0008] To achieve the above-mentioned and other related objectives, the present invention provides, in a first aspect, a blast furnace long-flow tempering co-production process with near-zero carbon emissions, comprising the following steps:

[0009] Decarburizing blast furnace gas by pressure swing adsorption to separate desorbed gas and decarburized gas;

[0010] The desorbed gas is subjected to liquefaction and rectification purification to obtain liquid carbon dioxide;

[0011] 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 from light hydrocarbons to form a mixed gas;

[0012] The mixed coal gas is washed with low-temperature methanol, subjected to temperature swing adsorption and two-stage pressure swing adsorption to separate into two streams for synthesizing ethylene glycol, wherein one stream includes CO and N2, and the other stream includes H2.

[0013] Furthermore, the liquid carbon dioxide is used for oil recovery, storage or as a raw material for synthesizing methanol.

[0014] Furthermore, 80% or more of the decarbonized gas is recycled to the blast furnace, and 20% or less of the decarbonized gas is mixed with refined converter gas and coke oven gas converted to light hydrocarbons to form a mixed gas.

[0015] Furthermore, the non-condensable gas separated in the desorbed gas distillation process is used to recover cooling energy and then returned to the blast furnace gas for pressure swing adsorption decarbonization, thereby recovering reducing components again and achieving 100% recovery of reducing components in the blast furnace gas.

[0016] Furthermore, the decarbonized gas and the refined converter gas are subjected to catalytic desulfurization and deoxygenation purification, and then mixed with the coke oven gas that has been converted to light hydrocarbons to form a mixed gas.

[0017] Furthermore, the process further comprises the following steps:

[0018] The pre-treated blast furnace gas is subjected to pressure swing adsorption decarbonization.

[0019] The refined converter gas is obtained by pre-treating the converter gas produced as a by-product in the converter steelmaking process.

[0020] The coke oven gas converted to light hydrocarbons is pre-treated and then mixed with decarbonized gas and refined converter gas to form a mixed gas;

[0021] The pretreatment process includes at least one of dust removal, cooling, desulfurization and pressurization.

[0022] Furthermore, before the low-temperature methanol washing, the decarbonized gas, the refined converter gas, and the coke oven gas converted to light hydrocarbons in the mixed gas all meet at least one of the following conditions (a) to (d):

[0023] (a) Temperature is less than or equal to 40°C;

[0024] (b) oxygen content is less than or equal to 50 ppm;

[0025] (c) The hydrogen sulfide content is less than or equal to 0.1 ppm;

[0026] (d) The pressure is 2.0 to 3.5 MPa.

[0027] Furthermore, the mixed coal gas after low-temperature methanol washing treatment includes H2, CO, N2 and other impurities, and the other impurities and their concentration requirements include: methanol ≤ 20 ppm, CO2 ≤ 20 ppm, sulfide ≤ 0.1 ppm, oxygen ≤ 50 ppm.

[0028] Furthermore, during the low-temperature methanol washing process, the methanol that absorbs impurities is recycled after methanol recovery treatment and returned to the low-temperature methanol washing process for recycling. The separated impurities hydrogen sulfide and CO2 enter the desorption gas drying process for drying treatment, and then undergo deep-cold liquefaction and distillation together with the desorption gas.

[0029] Furthermore, the mixed coal gas after the low-temperature methanol washing treatment is subjected to temperature swing adsorption to remove heavy impurity components, wherein the heavy impurity components include methanol and water.

[0030] Furthermore, the mixed coal gas after temperature swing adsorption treatment is separated into two streams through two-stage pressure swing adsorption, and the two-stage pressure swing adsorption includes stage I pressure swing adsorption and stage II pressure swing adsorption performed in sequence. The stream separated by stage I pressure swing adsorption includes CO and N2, and the stream separated by stage II pressure swing adsorption includes H2; preferably, the stream separated by stage I pressure swing adsorption includes CO and N2, and the H2 content is less than or equal to 50ppm, and the stream separated by stage II pressure swing adsorption includes H2, and the CO content is less than or equal to 20ppm.

[0031] Furthermore, the process of synthesizing ethylene glycol adopts catalytic coupling hydrogenation technology, comprising the following steps:

[0032] Dimethyl oxalate is synthesized using methyl nitrite as raw material and a stream containing CO and N2 as raw gas and diluent;

[0033] The dimethyl oxalate synthesized in the above steps is used to synthesize ethylene glycol using a stream containing H2 as raw gas.

[0034] Furthermore, the process also includes the following steps: supplementing hydrogen during the synthesis of ethylene glycol; preferably, the volume flow ratio of the logistics including H2 to the supplementary hydrogen is 1:0.5~1.5; more preferably, the supplementary hydrogen comes from "green hydrogen" prepared from renewable energy, and the oxygen produced as a by-product when preparing "green hydrogen" from renewable energy is purified and pressurized and then fed into the oxygen blast furnace and converter for use.

[0035] A second aspect of the present invention provides a near-zero carbon emission blast furnace long-process tempering co-production process system, comprising:

[0036] The first unit includes a pressure swing adsorption decarbonization system for separating blast furnace gas into desorbed gas and decarbonized gas, and a liquefaction and rectification purification system for liquefying and rectifying the desorbed gas to obtain liquid carbon dioxide;

[0037] The second unit includes a catalytic desulfurization and deoxygenation system for catalytically desulfurizing and deoxidizing the decarbonized gas and the refined converter gas;

[0038] A third unit, comprising a light hydrocarbon conversion system for converting coke oven gas into light hydrocarbons;

[0039] The fourth unit includes a coal gas mixing system, a low-temperature methanol washing system, a temperature swing adsorption system and a two-stage pressure swing adsorption system arranged in sequence according to the process flow. The coal gas mixing system is connected to the pressure swing adsorption decarbonization system and the light hydrocarbon conversion system, and is used to mix the decarbonized gas, the refined converter gas, and the coke oven gas converted to light hydrocarbons to form a mixed coal gas. The low-temperature methanol washing system, the temperature swing adsorption system and the two-stage pressure swing adsorption system are used to perform low-temperature methanol washing, temperature swing adsorption and two-stage pressure swing adsorption on the mixed coal gas in sequence to separate two streams for synthesizing ethylene glycol, one of which includes CO and N2, and the other includes H2.

[0040] Furthermore, the liquefaction, distillation and purification system includes a liquid carbon dioxide outlet, and the process system also includes a methanol synthesis unit, which is connected to the liquid carbon dioxide outlet.

[0041] Furthermore, the pressure swing adsorption decarbonization system includes a decarbonization gas outlet end, and the decarbonization gas outlet end is connected to the blast furnace reducing gas inlet end.

[0042] Furthermore, the liquefaction distillation purification system includes a distillation device and a precooler. The distillation equipment includes a non-condensable gas outlet end, which is connected to the precooler. The precooler uses non-condensable gas as a cold source. The precooler includes a cold source outlet end, which is connected to the air inlet end of the pressure swing adsorption decarbonization system.

[0043] Furthermore, the first unit also includes a first pretreatment system for pretreating blast furnace gas discharged from the blast furnace.

[0044] Furthermore, the second unit also includes a second pretreatment system for pretreating converter gas produced as a by-product in the converter steelmaking process to obtain refined converter gas.

[0045] Furthermore, the third unit also includes a third pretreatment system disposed after the light hydrocarbon conversion system for pretreating the coke oven gas that has undergone light hydrocarbon conversion.

[0046] Furthermore, the first pretreatment system, the second pretreatment system or the third pretreatment system includes at least one of the following equipment: dust removal equipment, cooling equipment, desulfurization equipment, and pressurizing equipment.

[0047] Furthermore, the coal gas mixing system includes a pressurizing device for pressurizing the mixed coal gas.

[0048] Furthermore, the fourth unit also includes a methanol recovery system for recovering the methanol that absorbs impurities during the low-temperature methanol washing process; the liquefaction distillation purification system includes a drying device for drying the desorbed gas, and the methanol recovery system is connected to the drying device to send the impurities hydrogen sulfide and CO2 separated by the methanol recovery treatment into the drying device.

[0049] Furthermore, the two-stage pressure swing adsorption system includes a stage I pressure swing adsorption device and a stage II pressure swing adsorption device arranged in sequence according to the process flow. The stage I pressure swing adsorption device is used to perform stage I pressure swing adsorption on the mixed coal gas after the temperature swing adsorption treatment to separate the logistics including CO and N2, and the stage II pressure swing adsorption device is used to perform stage II pressure swing adsorption on the mixed coal gas after the stage I pressure swing adsorption treatment to separate the logistics including H2.

[0050] Furthermore, the process system also includes a dimethyl oxalate synthesis unit and an ethylene glycol synthesis unit. The dimethyl oxalate synthesis unit is connected to a two-stage pressure swing adsorption system and is used to synthesize dimethyl oxalate using a logistics including CO and N2 as raw gas; the ethylene glycol synthesis unit is connected to the dimethyl oxalate synthesis unit and the two-stage pressure swing adsorption system and is used to synthesize ethylene glycol using dimethyl oxalate synthesized by the dimethyl oxalate synthesis unit as raw material and a logistics including H2 as raw gas.

[0051] Furthermore, the process system also includes a hydrogen replenishing unit, which is used to replenish hydrogen during the process of synthesizing ethylene glycol.

[0052] As described above, the near-zero carbon emission blast furnace long-process steelmaking co-production process system and its system of the present invention have the following beneficial effects: the technical solution of the present invention mainly utilizes the pressure swing adsorption decarbonization system, and combines cooling liquefaction and distillation separation to produce high-purity liquid carbon dioxide products; a portion of the decarbonized gas is recycled back to the blast furnace after heating to continue participating in the reduction reaction, and the overall energy consumption is low; and the surplus decarbonized gas, refined converter gas and coke oven gas converted from light hydrocarbons are mixed together and then separated by low-temperature methanol decarbonization, temperature swing adsorption and two-stage pressure swing adsorption process to separate CO+N2 and H2 for the synthesis of ethylene glycol; in addition, by supplementing a portion of hydrogen (preferably green hydrogen), the three types of gas resources of the steel enterprise can be fully utilized for their chemical energy, rather than for thermal energy, which is an inefficient utilization method. The solution of the present invention utilizes surplus decarbonized gas, coke oven gas and converter gas as raw materials for the manufacture of chemical products, achieving "carbon sequestration and emission reduction" and increasing value and efficiency, which can significantly reduce the consumption of primary energy from the source.

[0053] The present invention, through research and analysis of coal-to-methanol and ethylene glycol processes, finds that the essence of the coal route is to use synthesis gas to produce methanol and ethylene glycol, and the energy consumption of the coal gasification section accounts for more than 30% of the overall coal-to-methanol and ethylene glycol energy consumption. If a synthesis gas source that is not produced by a coal gasification process is used, and carbon dioxide hydrogenation to produce methanol and catalytic coupling hydrogenation technology are used to produce ethylene glycol, the cost of equipment such as coal gasification process construction and gasifiers can be saved, effectively reducing the production cost of methanol and ethylene glycol, and making full use of renewable energy. Secondly, the present invention finds that in the dimethyl oxalate synthesis section of the synthesis gas to ethylene glycol process, in addition to the need to add reaction gas CO, it is also necessary to introduce N2 from an air separation unit. The role of N2 is to absorb the heat of the dimethyl oxalate synthesis reaction and dilute the toxicity of gaseous methyl nitrite. The introduction of N2 increases the gas usage cost of the process. In the scheme of the present invention, converter gas, blast furnace gas and coke oven gas themselves contain nearly 10% N2. This part of N2 is not separated from CO during the gas separation process. This operation not only avoids the cost of separating CO and N2 during the purification process, but also reduces the cost of reintroducing N2 gas during the synthesis of dimethyl oxalate, thereby effectively reducing the production cost of ethylene glycol.

[0054] To sum up, the technical solution provided by the present invention is based on my country's national conditions and the reality of the steel industry, gives full play to the unique process advantages of the steel industry, and through the ideas and advantages of steel-coke fusion and steel-chemical co-production, converts "carbon" from fuel into raw materials, and solidifies from emissions into products, taking a green, low-carbon and efficient development path; it mainly utilizes the oxygen blast furnace gas decarbonization self-circulation system to reduce blast furnace ironmaking carbon emissions. In addition, the surplus blast furnace gas, coke oven gas and converter gas are used as raw materials for manufacturing chemical products, which can achieve "carbon sequestration and emission reduction" and increase value and efficiency, and can greatly reduce the consumption of primary energy from the source. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Shown is a schematic flow diagram of a blast furnace long-process tempering co-production process with near-zero carbon emissions according to one embodiment of the present invention.

[0056] Figure 2 Shown is a schematic diagram of the utilization of liquid carbon dioxide in one embodiment of the present invention.

[0057] Figure 3 Shown is a schematic diagram of the process of liquefying and distilling the desorbed gas to obtain liquid carbon dioxide and a schematic diagram of the layout of the liquefaction and distillation purification system in one embodiment of the present invention.

[0058] Figure 4 It shows a schematic flow diagram of a blast furnace long-process tempering co-production process with near-zero carbon emissions according to another embodiment of the present invention.

[0059] Figure 5Shown is a schematic diagram of the process flow and the layout of the process system of a blast furnace long-process tempering co-production process with near-zero carbon emissions in another embodiment of the present invention.

[0060] Figure 6 Shown is a schematic diagram of the process of synthesizing dimethyl oxalate and ethylene glycol in one embodiment of the present invention, as well as a schematic diagram of the layout of a dimethyl oxalate synthesis unit and an ethylene glycol synthesis unit.

[0061] Figure 7 Shown is a schematic diagram of the layout of a blast furnace long-process tempering co-production process system with near-zero carbon emissions in another embodiment of the present invention.

[0062] Figure 8 Shown is a schematic diagram of the process flow and the layout of the process system of a blast furnace long-process tempering co-production process with near-zero carbon emissions in another embodiment of the present invention. DETAILED DESCRIPTION

[0063] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0064] It should be noted that the diagrams provided in the present embodiment are only schematic illustrations of the basic concept of the present invention. The diagrams only show the components related to the present invention and are not drawn according to the number, shape and size of the components during actual implementation. The type, quantity and ratio of each component during actual implementation can be changed at will, and the component layout type may also be more complex. The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read. They are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be considered as the scope of the implementation of the present invention without substantially changing the technical content.

[0065] First, it should be noted that the following embodiments and Figures 1 to 8 The abbreviations in the table refer to the following information:

[0066] MN-methyl nitrite, chemical formula: CH3ONO;

[0067] DMO-dimethyl oxalate, chemical formula: (COOCH3)2;

[0068] DMC-dimethyl carbonate, chemical formula: CO(OCH3)2;

[0069] MG-methyl glycolate, chemical formula: HOCH2CO2CH3;

[0070] EG-ethylene glycol, chemical formula: HOCH2CH2OH;

[0071] ET-ethanol, chemical formula: CH3CH2OH;

[0072] TSA, Temperature Swing Adsorption, temperature swing adsorption;

[0073] PSA, Pressure Swing Adsorption, pressure swing adsorption.

[0074] See also Figure 1 , Figure 1 This is a schematic flow chart of a near-zero carbon emission blast furnace long-process tempering co-production process in one embodiment of the present application.

[0075] like Figure 1 As shown, a disclosed embodiment of the present application provides a blast furnace long-flow tempering co-production process with near-zero carbon emissions, including the following steps:

[0076] Decarburizing blast furnace gas by pressure swing adsorption to separate desorbed gas and decarburized gas;

[0077] The desorbed gas is subjected to liquefaction and rectification purification to obtain liquid carbon dioxide;

[0078] 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 from light hydrocarbons to form a mixed gas;

[0079] The mixed coal gas is washed with low-temperature methanol, subjected to temperature swing adsorption and two-stage pressure swing adsorption to separate into two streams for synthesizing ethylene glycol, wherein one stream includes CO and N2, and the other stream includes H2.

[0080] Among them, the blast furnace gas is decarbonized by pressure swing adsorption to separate the desorbed gas and the decarbonized gas using vacuum pressure swing adsorption technology, specifically: the blast furnace gas first enters the adsorption tower (multi-tower) from the bottom, and after the adsorbent in the adsorption tower adsorbs the CO2 component, the decarbonized gas is discharged from the top of the adsorption tower; the adsorbed component in the adsorption tower is the desorbed gas, and a part of the desorbed gas will be released by first reducing the pressure. When the pressure of the adsorption tower drops to near normal pressure, the vacuum pump is then used to evacuate the remaining desorbed gas and desorb it completely and then discharge it into the desorbed gas buffer tank. In some embodiments, the liquid carbon dioxide is used for oil recovery, storage, or as a raw material for synthesizing methanol. Specifically, as Figure 2 As shown, liquid carbon dioxide is directly transported to geological storage sites and oil fields for oil recovery, or methanol is synthesized by the method of hydrogenating carbon dioxide to produce methanol, such as synthesizing methanol with "green hydrogen" chemical produced from renewable energy, and the methanol is sold as a product after distillation and purification.

[0081] Among them, "green hydrogen" produced from renewable energy can be combined with liquid carbon dioxide to synthesize the chemical product methanol through the following methods: hydrogen is produced by electrolysis of water using renewable energy electricity. After purification and pressurization, the hydrogen is fed into a methanol synthesis reactor. Liquid carbon dioxide enters the methanol synthesis reactor and synthesizes methanol with hydrogen. The methanol is purified by a methanol distillation system and can be sold as a product. At the same time, the oxygen produced as a byproduct of hydrogen production by electrolysis of water can be purified and pressurized before being fed into oxygen blast furnaces and converters. In some embodiments, 80% or more of the decarbonized gas is recycled back to the blast furnace, and 20% or less of the decarbonized gas is mixed with refined converter gas and coke oven gas that has been converted to light hydrocarbons to form a mixed gas.

[0082] In some embodiments, the decarbonized gas is heated and then recycled to the blast furnace for use as reducing gas, preferably heated to 800° C. to 1000° C. Heating the decarbonized gas to 800° C. to 1000° C. and recycling it to the blast furnace as a reducing agent not only achieves the recycling of blast furnace gas and increases the reducing gas content in the blast furnace bosh gas, but also promotes indirect reduction in the blast furnace and reduces direct reduction, thereby reducing the consumption of coke and coal fuels during the blast furnace ironmaking process and effectively reducing CO2 emissions.

[0083] In the embodiments of the present application, blast furnace gas refers to the blast furnace gas produced when ironmaking is carried out in an oxygen blast furnace to obtain molten iron. The blast furnace gas produced by oxygen blast furnace ironmaking has a relatively high dust content and sulfur content, and has a high temperature and low pressure. Therefore, pretreatment is required before pressure swing adsorption decarbonization.

[0084] In some embodiments, the pretreatment process of blast furnace gas includes at least one of the following steps: dust removal, cooling, and desulfurization; preferably, the dust content of the blast furnace gas after pretreatment is less than 10 mg / Nm 3, the temperature is reduced to 30-40℃, and the H2S content is less than 10mg / Nm 3 , increase the pressure to 0.2~0.8MPa.

[0085] In some embodiments, the CO2 content in the decarbonized gas separated by pressure swing adsorption decarbonization is less than 1%, and the pressure is 0.60-0.75 MPa.

[0086] In some embodiments, as Figure 3 As shown, the process of obtaining liquid carbon dioxide by liquefaction and purification of the desorbed gas includes the following steps: pressurization, drying, deep-cold liquefaction, and distillation separation; the non-condensable gas (mainly composed of CO and CO2) separated during the desorbed gas distillation process is returned to the blast furnace gas for pressure swing adsorption decarbonization after recovering the cold energy, and the reducing components are recovered again, thereby achieving 100% recovery of the reducing components in the blast furnace gas.

[0087] In some embodiments, when the desorbed gas is pressurized, the outlet pressure of the desorbed gas pressurization system compressor is 2.50-3.0 MPa, the outlet temperature is 30-40°C, no impurities are added to the outlet medium, and the free water content is ≯7 g / Nm 3 ;

[0088] After drying in a drying system, the desorbed gas enters a cryogenic liquefaction system for cryogenic liquefaction. It then enters a distillation separation system for distillation and separation to produce liquid CO2. The drying system includes a dryer, the cryogenic liquefaction system includes a refrigerant, and the distillation separation system includes a distillation tower. The pressurized desorbed gas first passes through a dryer to remove moisture to prevent freezing and blockage of pipes and equipment during cryogenic liquefaction. The dried desorbed gas is then fed into a precooler and cooled to 10-30°C. The cooling source is the non-condensable gas at the top of the distillation tower. The pre-cooled desorbed gas enters a refrigerator and is deep-chilled to -30--40°C before being liquefied. The liquefied desorbed gas is then fed into a distillation tower for separation and purification. High-purity liquefied CO2 is discharged from the bottom of the distillation tower. The non-condensable gas discharged from the top of the distillation tower is recovered for cooling and then returned to the adsorption tower inlet for further recovery of reducing components.

[0089] In some embodiments, the refined converter gas is obtained by pre-treating and pressurizing the converter gas produced as a by-product in the converter steelmaking process. The pre-treatment process of the converter gas includes dust removal, cooling, and desulfurization.

[0090] In some embodiments, as Figure 4 As shown, the decarbonized gas and the refined converter gas are catalytically desulfurized and deoxygenated, and then mixed with the coke oven gas that has been converted to light hydrocarbons to form a mixed gas.

[0091] Since the converter gas and the excess decarbonization gas contain a certain amount of sulfides, the main types are COS and H2S, and COS needs to be converted into H2S before it can be removed; at the same time, since the converter gas and decarbonization gas components contain H2, a reduction method is used to convert COS, that is, a hydrogenation conversion method. In some embodiments, the hydrogenation reaction conditions are 200-250°C, 0.5-1.0MPa, and the catalyst used is a Ni-Mo system with a carrier of γ-Al2O3. After hydrogenation, the volume content of COS in the gas is reduced to 4×10 -8 .

[0092] Furthermore, the mixed gas of converter gas and excess decarburized gas contains approximately 0.30% oxygen. Since the mixed gas in this unit contains a small amount of O2, the H2 content is sufficient for deoxidation. Therefore, in some embodiments, the catalytic deoxidation reaction conditions are 60-150°C, 0.5-2.0 MPa, and a Pt-γ-Al2O3 catalyst. The O2 in the gas reacts with H2 over the catalyst to produce H2O, reducing the oxygen content to less than 150 ppm.

[0093] In some embodiments, the coke oven gas converted to light hydrocarbons is obtained by converting high-temperature coke oven gas, a byproduct of the coking process, into light hydrocarbons through a non-catalytic conversion process. The high-temperature coke oven gas produced as a byproduct of the coking process has a temperature of 700-800°C. To fully utilize its sensible heat and eliminate the need for purification, a non-catalytic partial oxidation process is employed. The reaction temperature in this process is 1200-1500°C, and the feedstock consists of high-temperature coke oven gas, 350-400°C high-pressure steam, and 200-300°C oxygen. No catalyst is present in the non-catalytic converter. After the reaction, all light hydrocarbons and compounds such as benzene in the gas are consumed, leaving the reaction product as high-temperature, high-pressure gas. Heat is recovered and reused through a multi-stage heat exchange system, primarily through preheating the feedstock and absorbing heat from demineralized water to produce steam. After cooling through multi-stage heat exchange, the high-temperature gas is dehydrated in a separator tank. The dehydrated gas is then purified, dust-cleaned, and pressurized before being sent to a low-temperature methanol wash.

[0094] In some embodiments, the coke oven gas converted to light hydrocarbons is pretreated and then mixed with decarbonized gas and refined converter gas to form a mixed gas. The pretreatment process of the coke oven gas converted to light hydrocarbons includes dust removal and multi-stage heat exchange and cooling.

[0095] In the above embodiments, the dust removal, cooling, desulfurization, and pressurization of blast furnace gas, converter gas, and coke oven gas can be achieved by the following means: dust removal by gravity dust removal, bag dust removal, or a combination of the two; cooling by a heat exchanger; removal of sulfides from the gas by physical adsorption, chemical desulfurization, or a combination of the two; and pressurization by a compressor, which can be a screw compressor or a centrifugal compressor, with an outlet pressure of 0.65 to 0.80 MPa, an outlet temperature of 30 to 40°C, no impurities added to the outlet medium, and a free water content of ≯7 g / Nm 3 .

[0096] In some embodiments, before the low-temperature methanol wash, the decarbonized gas, the refined converter gas, and the coke oven gas converted to light hydrocarbons in the mixed coal gas all meet at least one of the following conditions (a) to (d):

[0097] (a) Temperature is less than or equal to 40°C;

[0098] (b) oxygen content is less than or equal to 50 ppm;

[0099] (c) The hydrogen sulfide content is less than or equal to 0.1 ppm;

[0100] (d) The pressure is 2.0 to 3.5 MPa.

[0101] In some embodiments, the mixed coal gas after low-temperature methanol washing treatment includes H2, CO, N2 and other impurities, and the other impurities and their concentration requirements include: methanol ≤ 20 ppm, CO2 ≤ 20 ppm, sulfide ≤ 0.1 ppm, oxygen ≤ 50 ppm.

[0102] In some embodiments, as Figure 5 As shown, in the low-temperature methanol washing process, the methanol that absorbs impurities is recycled after methanol recovery treatment and returned to the low-temperature methanol washing for recycling. The separated impurities hydrogen sulfide and CO2 enter the desorption gas drying process for drying treatment, and then undergo deep-cold liquefaction and distillation together with the desorption gas.

[0103] In the above embodiment, the purified converter gas and excess decarbonized gas are mixed with the coke oven gas that has undergone non-catalytic conversion and purification and pressurization, and the two gases enter the low-temperature methanol washing system. In the low-temperature methanol washing system, the mixed gas is countercurrently contacted with low-temperature methanol (-55 to -60°C). The methanol absorbs impurities such as hydrogen sulfide and CO2 from the gas, purifying the gas. After absorption, flash evaporation, desorption, and thermal regeneration, the gas is primarily composed of H2, CO, and N2, with the concentrations of other impurities reduced to the required purity (methanol ≤ 20 ppm, CO2 ≤ 20 ppm, sulfide ≤ 0.1 ppm, and oxygen ≤ 50 ppm). The methanol that absorbed the impurities is processed in the methanol recovery system and then returned to the low-temperature methanol washing process for recycling. The separated hydrogen sulfide and CO2 enter the desorbed gas drying system after the blast furnace gas decarbonization system for drying, and then enter the liquefaction and distillation purification system together with the desorbed gas after the blast furnace gas decarbonization.

[0104] In some embodiments, the mixed coal gas after low-temperature methanol washing is subjected to a temperature swing adsorption process to remove heavy impurity components, wherein the heavy impurity components include methanol and water; further, heated hydrogen is then used for regeneration, so that the temperature swing adsorption process can operate continuously.

[0105] In some embodiments, the mixed coal gas treated by the temperature swing adsorption process is separated into two streams by a two-stage pressure swing adsorption process, and the two-stage pressure swing adsorption includes stage I pressure swing adsorption and stage II pressure swing adsorption performed sequentially. The stream separated by stage I pressure swing adsorption includes CO and N2, and the stream separated by stage II pressure swing adsorption includes H2; preferably, the stream separated by stage I pressure swing adsorption includes CO and N2, and the H2 content is less than or equal to 50 ppm, and the stream separated by stage II pressure swing adsorption includes H2, and the CO content is less than or equal to 20 ppm.

[0106] The mixed coal gas treated by temperature swing adsorption enters the two-stage pressure swing adsorption system. The stage I pressure swing adsorption equipment mainly separates CO and N2 components. The H2 content of the CO+N2 stream needs to be strictly controlled. H2 is toxic to the DMO synthesis catalyst. It is pressurized to 0.5MPa through the pressurization system and then sent to the dimethyl oxalate synthesis unit; the hydrogen component discharged from the top of the adsorption tower in the stage I pressure swing adsorption equipment enters the stage II pressure swing adsorption equipment. The CO content in the hydrogen product needs to be strictly controlled (the gas raw material in the EG synthesis unit cannot contain CO). H2 is discharged from the top of the tower and sent to the ethylene glycol synthesis reactor for use as a raw material for hydrogenating dimethyl oxalate to synthesize ethylene glycol.

[0107] In some embodiments, the process for synthesizing ethylene glycol adopts catalytic coupling hydrogenation technology, comprising the following steps:

[0108] Dimethyl oxalate is synthesized using methyl nitrite as raw material and a stream containing CO and N2 as raw gas and diluent;

[0109] The dimethyl oxalate synthesized in the above steps is used to synthesize ethylene glycol using a stream containing H2 as raw gas.

[0110] like Figure 6 As shown, in some embodiments, the process of synthesizing dimethyl oxalate and ethylene glycol is as follows:

[0111] The CO separated from the mixed coal gas enters the dimethyl oxalate synthesis unit, which includes a DMO reactor, a DMO distillation system, and an MN pressurization system. In order to improve the utilization rate of raw materials, an MN regeneration reactor and a methanol recovery system can also be set up. This unit is divided into two reactions:

[0112] NO, O2, and CH3OH undergo regeneration reactions to synthesize methyl nitrite (MN), and CO and methyl nitrite (MN) catalytically couple to synthesize DMO. The chemical reaction formula and specific reaction process involved are as follows:

[0113] 4CH3OH + O2 + 4NO = 4CH3ONO + 2H2O; 2CO + 2CH3ONO = (COOCH3)2 + 2NO (main reaction), CO + 2CH3ONO = CO(OCH3)2 + 2NO (side reaction). NO and O2 are mixed and enter the lower part of the MN regeneration reactor distillation tower, while CH3OH is sprayed down from the upper part of the MN regeneration reactor distillation tower. The lower gas and upper liquid react in countercurrent contact at a reaction temperature of 25-150°C and a pressure of 0.5 MPa to produce MN (gas phase). The reaction products are separated into reaction products through the distillation and stripping sections of the MN regeneration reactor distillation tower. The gas at the top outlet (NO, MN, O2) is pressurized to the liquid (water, methanol) flowing out from the bottom of the tower. The liquid (water, methanol) enters the MN regeneration reactor's conventional distillation tower for methanol-water separation. The methanol recovered from the top of the tower is sent to the top of the MN regeneration reactor distillation tower.

[0114] The gas at the top outlet of the tower (NO, MN, O2) is pressurized by the MN pressurizing system and enters the DMO synthesis reactor together with the pressurized CO and N2. CO serves as the reaction raw material, and N2 absorbs the heat released during the DMO synthesis process and dilutes the toxicity of the MN gas (the catalytic coupling reaction of CO and MN is a highly exothermic reaction, and MN is a toxic gas).

[0115] The DMO reactor product is a mixture of gas and liquid. The reaction product first enters a flash separation tank for gas-liquid separation. The liquid phase is mainly composed of DMO, DMC, and CH3OH. The liquid phase enters the DMO distillation system's refining distillation tower. The overhead output is DMC / CH3OH, and the bottom output is DMO. The refined DMO is sent to the ethylene glycol synthesis unit and hydrogenated with H2 to synthesize EG. The gas phase is mainly composed of CO, N2, NO, etc. After replenishing O2, the gas phase is sent back to the bottom of the MN reactor distillation tower to participate in the MN regeneration reaction.

[0116] After obtaining a high-purity DMO product through the CO coupling regeneration reaction, it enters the ethylene glycol synthesis unit. In the ethylene glycol synthesis unit, H2 and dimethyl oxalate are hydrogenated to synthesize ethylene glycol. The reaction product undergoes heat exchange distillation separation and other processes to obtain the target product ethylene glycol. The ethylene glycol synthesis unit includes an EG synthesis reactor, a flash separator, a methanol removal system, and an EG distillation system. This process is mainly divided into two steps and one step. The two-step reaction is that DMO first reacts with H2 to produce methyl glycolate (MG), and then MG is hydrogenated to produce ethylene glycol. At the same time, a side reaction occurs to produce ethanol (ET). The chemical reaction formula and specific reaction process involved are as follows:

[0117] DMO+2H2=MG+CH3OH; MG+2H2=EG+CH3OH (main reaction), EG+H2=ET+H2O (side reaction).

[0118] The DMO material from the dimethyl oxalate synthesis unit is mixed with H2 and heated by the outlet product of the EG synthesis reactor before entering the EG synthesis reactor. The discharge of the EG synthesis reactor is heat exchanged with the feed flow, and then cooled to an appropriate temperature using a cooler before entering the flash separation tank for gas-liquid phase separation. The gas phase is recirculated and mixed with the DMO flow before re-entering the EG synthesis reactor. The liquid phase is processed through the methanol recovery tower of the demethanolation system, the dehydration tower, and the distillation tower of the EG distillation system to obtain the EG product.

[0119] In some embodiments, the process further comprises the step of supplementing hydrogen during the ethylene glycol synthesis process; preferably, the volume flow ratio of the H2 stream to the supplemented hydrogen is 1:0.5-1.5. The hydrogen can be derived from "green hydrogen" produced from renewable energy.

[0120] See also Figure 7 , Figure 7 This is a schematic diagram of the layout of a blast furnace long-process tempering co-production process system with near-zero carbon emissions in another embodiment of the present application.

[0121] like Figure 7 As shown, another disclosed embodiment of the present application provides a blast furnace long-process tempering co-production process system with near-zero carbon emissions, comprising:

[0122] The first unit includes a pressure swing adsorption decarbonization system for separating blast furnace gas into desorbed gas and decarbonized gas, and a liquefaction and rectification purification system for liquefying and rectifying the desorbed gas to obtain liquid carbon dioxide;

[0123] The second unit includes a catalytic desulfurization and deoxygenation system for catalytically desulfurizing and deoxidizing the decarbonized gas and the refined converter gas;

[0124] A third unit, comprising a light hydrocarbon conversion system for converting coke oven gas into light hydrocarbons;

[0125] The fourth unit includes a coal gas mixing system, a low-temperature methanol washing system, a temperature swing adsorption system and a two-stage pressure swing adsorption system arranged in sequence according to the process flow. The coal gas mixing system is connected to the pressure swing adsorption decarbonization system and the light hydrocarbon conversion system, and is used to mix the decarbonized gas, the refined converter gas, and the coke oven gas converted to light hydrocarbons to form a mixed coal gas. The low-temperature methanol washing system, the temperature swing adsorption system and the two-stage pressure swing adsorption system are used to perform low-temperature methanol washing, temperature swing adsorption and two-stage pressure swing adsorption on the mixed coal gas in sequence to separate two streams for synthesizing ethylene glycol, one of which includes CO and N2, and the other includes H2.

[0126] In some embodiments, the liquefaction, distillation and purification system includes a liquid carbon dioxide outlet, and the process system further includes a methanol synthesis unit, which is connected to the liquid carbon dioxide outlet.

[0127] In some embodiments, the pressure swing adsorption decarbonization system includes a decarbonization gas outlet end, and the decarbonization gas outlet end is connected to the blast furnace reducing gas inlet end.

[0128] In some embodiments, as Figure 3 As shown, the liquefaction distillation purification system includes a distillation device and a precooler. The distillation equipment includes a non-condensable gas outlet end, which is connected to the precooler. The precooler uses non-condensable gas as a cold source. The precooler includes a cold source outlet end, which is connected to the air inlet end of the pressure swing adsorption decarbonization system.

[0129] In some embodiments, the first unit further includes a first pretreatment system for pretreating blast furnace gas discharged from the blast furnace.

[0130] In some embodiments, the second unit further includes a second pretreatment system for pretreating converter gas produced as a by-product in the converter steelmaking process to obtain refined converter gas.

[0131] In some embodiments, the third unit further includes a third pretreatment system disposed after the light hydrocarbon conversion system for pretreating the coke oven gas that has undergone light hydrocarbon conversion.

[0132] In some embodiments, the first pretreatment system, the second pretreatment system or the third pretreatment system includes at least one of the following equipment: dust removal equipment, cooling equipment, desulfurization equipment, and pressurization equipment.

[0133] In some embodiments, the gas mixing system includes a pressurizing device for pressurizing the mixed gas.

[0134] In some embodiments, as Figure 5 As shown, the fourth unit also includes a methanol recovery system for recovering the methanol that absorbs impurities during the low-temperature methanol washing process; the liquefaction distillation purification system includes a drying device for drying the desorbed gas, and the methanol recovery system is connected to the drying device to feed the impurity hydrogen sulfide CO2 separated by the methanol recovery treatment into the drying device.

[0135] In some embodiments, as Figure 5 As shown, the two-stage pressure swing adsorption system includes a stage I pressure swing adsorption device and a stage II pressure swing adsorption device arranged in sequence according to the process flow. The stage I pressure swing adsorption device is used to perform stage I pressure swing adsorption on the mixed coal gas after the temperature swing adsorption treatment to separate the logistics including CO and N2. The stage II pressure swing adsorption device is used to perform stage II pressure swing adsorption on the mixed coal gas after the stage I pressure swing adsorption treatment to separate the logistics including H2.

[0136] In some embodiments, as Figure 6 As shown, the process system also includes a dimethyl oxalate synthesis unit and an ethylene glycol synthesis unit. The dimethyl oxalate synthesis unit is connected to a two-stage pressure swing adsorption system and is used to synthesize dimethyl oxalate using a logistics including CO and N2 as raw gas; the ethylene glycol synthesis unit is connected to the dimethyl oxalate synthesis unit and the two-stage pressure swing adsorption system and is used to synthesize ethylene glycol using dimethyl oxalate synthesized in the dimethyl oxalate synthesis unit as raw material and a logistics including H2 as raw gas.

[0137] In some embodiments, the process system further includes a hydrogen supplement unit, which is used to supplement hydrogen during the process of synthesizing ethylene glycol.

[0138] See also Figure 8 , Figure 8 This is a flow chart of a near-zero carbon emission blast furnace long-process tempering co-production process and a schematic diagram of the process system layout in another embodiment of the present application.

[0139] like Figure 8As shown, another disclosed embodiment of the present application provides a blast furnace long process tempering co-production process and process system with near zero carbon emission, and the specific implementation process is as follows: 1. In this embodiment, 530m 3 Based on the oxygen blast furnace with a capacity of 10000 tons, the specific parameters are as follows:

[0140] Table 1

[0141]

[0142] 1) Raw material 1: blast furnace gas, with a volume fraction of carbon monoxide 44.30%, carbon dioxide 40.23%, hydrogen 10.57%, nitrogen 4.70%, and oxygen 0.20%; pressure 0.15 MPa, temperature 150°C, blast furnace gas volume 103218 Nm 3 / h.

[0143] 2) Raw material 2: coke oven gas, with a volume fraction of hydrogen 60.50%, methane 25%, carbon monoxide 8.00%, carbon dioxide 2.50%, nitrogen 1.50%, ethylene 1.50%, ethane 0.80%, and oxygen 0.20%; pressure 0.015 MPa, temperature 750°C, coke oven gas volume 11183 Nm 3 / h(at 400Nm 3 / ton of coke measurement).

[0144] 3) Raw material 3: converter gas, with a volume fraction of carbon monoxide 53.70%, nitrogen 26.80%, carbon dioxide 17.20%, hydrogen 2.00%, methane 0.10%, and oxygen 0.20%; pressure 0.012 MPa, temperature 40°C, converter gas volume 10083 Nm 3 / h(at 110Nm 3 / ton steel measurement).

[0145] 4) Raw material 4: Supplement green hydrogen, with a volume fraction of 99.99% hydrogen and 0.01% nitrogen; flow rate is 13621Nm 3 / h, pressure is 2.5MPa, and temperature is 40℃.

[0146] 2. If Figure 8 As shown, the process system of this embodiment includes:

[0147] The first unit includes a first pretreatment system, a pressure swing adsorption decarbonization system, a liquefaction distillation purification system, and a decarbonization gas heater. The first pretreatment system includes a dust removal device, a cooling device, a desulfurization device, and a pressurizing device that are sequentially connected according to the process flow; the blast furnace gas pressurized by the pressurizing device enters the pressure swing adsorption decarbonization system, and the pressure swing adsorption decarbonization system is used to separate the blast furnace gas into desorbed gas and decarbonization gas. The decarbonization gas separated by the pressure swing adsorption decarbonization system is discharged from the decarbonization gas outlet, and the decarbonization gas outlet is sequentially connected to the decarbonization gas heater and the blast furnace blowing system; the pressure swing adsorption decarbonization system separates The desorbed gas is discharged from the desorbed gas outlet, and the desorbed gas outlet is connected to a liquefaction rectification and purification system, which is used to liquefy and rectify the desorbed gas to obtain liquid carbon dioxide, including a pressurization system, a drying system, a cryogenic liquefaction system, a rectification and separation system, and a precooler connected in sequence according to the process flow. The rectification and separation system is provided with a rectification device, the rectification device includes a non-condensable gas outlet end, the non-condensable gas outlet end is connected to a precooler, the precooler uses non-condensable gas as a cold source, the precooler includes a cold source outlet end, and the cold source outlet end is connected to the air inlet end of the pressure swing adsorption decarbonization system;

[0148] The second unit includes a second pretreatment system and a catalytic desulfurization and deoxygenation system connected in sequence according to the process flow. The second pretreatment system is used to pretreat the converter gas produced as a by-product in the converter steelmaking process to obtain refined converter gas, including a dust removal device, a cooling device, a desulfurization device, and a pressurizing device connected in sequence according to the process flow. The catalytic desulfurization and deoxygenation system is used to catalytically desulfurize and deoxidize the decarbonized gas and the refined converter gas. The decarbonization gas outlet of the pressure swing adsorption decarbonization system is also connected to the air inlet of the catalytic desulfurization and deoxygenation system.

[0149] The third unit includes a light hydrocarbon conversion system and a third pretreatment system. The light hydrocarbon conversion system is used to convert the coke oven gas into light hydrocarbons. The third pretreatment system is arranged after the light hydrocarbon conversion system and is used to pretreat the coke oven gas after the light hydrocarbon conversion. The third pretreatment system includes dust removal equipment, cooling equipment, and desulfurization equipment.

[0150] The fourth unit includes a coal gas mixing system, a low-temperature methanol washing system, a temperature swing adsorption system and a two-stage pressure swing adsorption system arranged in sequence according to the process flow. The coal gas mixing system is connected to the catalytic desulfurization and deoxygenation system and the third pretreatment system, and is used to mix the decarbonized gas, the refined converter gas, and the coke oven gas converted to light hydrocarbons to form a mixed coal gas. The coal gas mixing system includes a pressurizing device for pressurizing the mixed coal gas; the low-temperature methanol washing system and the temperature swing adsorption system are used to perform low-temperature methanol washing and temperature swing adsorption on the mixed coal gas in sequence; the two-stage pressure swing adsorption system includes a stage I pressure swing adsorption device and a stage II pressure swing adsorption device arranged in sequence according to the process flow. The stage I pressure swing adsorption device is used to perform stage I pressure swing adsorption on the mixed coal gas after the temperature swing adsorption treatment to separate a logistics including CO and N2, and the stage II pressure swing adsorption device is used to perform stage II pressure swing adsorption on the mixed coal gas after the stage I pressure swing adsorption treatment to separate a logistics including H2.

[0151] The fourth unit also includes a methanol recovery system for recovering the methanol that absorbs impurities during the low-temperature methanol washing process. The methanol recovery system is connected to the desorbed gas drying system to feed the impurities hydrogen sulfide and CO2 separated by the methanol recovery process into the drying equipment;

[0152] A methanol synthesis unit is connected to the liquid carbon dioxide outlet of the liquefaction, rectification and purification system.

[0153] The dimethyl oxalate synthesis unit is connected to the I-stage pressure swing adsorption device and is used to synthesize dimethyl oxalate using a stream including CO and N2 as a raw gas; Figure 6 As shown, the dimethyl oxalate synthesis unit includes an MN regeneration reactor, an MN pressurizing system, a DMO reactor, and a DMO distillation system which are sequentially connected according to the process flow.

[0154] An ethylene glycol synthesis unit, the ethylene glycol synthesis unit is connected to the dimethyl oxalate synthesis unit and the stage II pressure swing adsorption device, and is used to synthesize ethylene glycol using the dimethyl oxalate synthesized by the dimethyl oxalate synthesis unit as a raw material and a stream containing H2 as a raw gas; Figure 6 As shown, the ethylene glycol synthesis unit includes an EG synthesis reactor, a flash separator, a methanol removal system, and an EG distillation system which are sequentially connected according to the process flow.

[0155] The hydrogen replenishing unit is used to replenish hydrogen during the process of synthesizing ethylene glycol; the hydrogen replenishing unit can be referred to Figure 2 , producing hydrogen through water electrolysis using renewable energy electricity.

[0156] 3. If Figure 1 As shown, the process flow of this embodiment is as follows:

[0157] Step 1: Blast furnace gas is first subjected to dust removal, desulfurization, cooling and pressurization, with the temperature dropping to below 40°C and the dust content below 10mg / Nm 3 , H2S is removed to 1ppm and the pressure is increased to 0.2~0.8MPa.

[0158] Step 2: The pressurized blast furnace gas is passed into the pressure swing adsorption decarbonization system, and the decarbonized gas with higher pressure is discharged from the top of the pressure swing adsorption decarbonization system. 80% of the decarbonized gas is heated to 800℃~1000℃ by the heater and circulated to the blast furnace, and the remaining 20% ​​of the decarbonized gas is sent to the catalytic desulfurization and deoxygenation system; the desorbed gas discharged from the bottom of the pressure swing adsorption decarbonization system after depressurization is mixed with the desorbed gas discharged by vacuum and sent to a pressurized system to 2.0~3.0MPa, dried, deep-cold liquefied and distilled for separation. Finally, a liquid carbon dioxide product with higher pressure is obtained at the bottom of the distillation tower, and the non-condensable gas at the top is returned to the inlet of the pressure swing adsorption decarbonization system after recovering the cold.

[0159] Step 3: The converter gas is first subjected to dust removal, desulfurization, cooling and pressurization to become refined converter gas. The refined converter gas is mixed with the surplus decarbonized gas for desulfurization and deoxygenation purification, and finally pressurized and sent to the low-temperature methanol washing system.

[0160] Step 4: The high-temperature coke oven gas directly enters the non-catalytic converter of the light hydrocarbon conversion system for light hydrocarbon conversion, and then undergoes dust removal, multi-stage heat exchange cooling and pressurization to 0.70MPa to form a mixed gas with the above-mentioned refined converter gas and surplus decarbonization gas, which is pressurized to 3.0MPa and then enters the low-temperature methanol washing system.

[0161] Step 5: After the mixed coal gas is decarbonized by low-temperature methanol, it is subjected to temperature swing adsorption and a two-stage pressure swing adsorption system. The CO+N2 logistics are separated from the stage I pressure swing adsorption equipment, and the H2 logistics are separated from the stage II pressure swing adsorption system.

[0162] Step 6: The CO+N2 stream separated from the stage I pressure swing adsorption equipment is pressurized to 0.5 MPa and then introduced into the DMO reactor as a raw material and diluent to synthesize dimethyl oxalate. The product is then distilled and methanol is recovered before being sent to the hydrogenation reaction.

[0163] Step 7: Separate the H2 stream from the stage II pressure swing adsorption equipment as a raw material and use it with the refined DMO to synthesize ethylene glycol in the EG synthesis reactor. The product is then flash-separated, demethanolized and distilled to obtain the ethylene glycol product.

[0164] 4. Processing results:

[0165] Liquid carbon dioxide product composition and output: 99.9% carbon dioxide, 0.1% carbon monoxide; flow rate is 80.11t / h, pressure is 2.5MPa, and temperature is -12℃.

[0166] Decarbonization gas composition and output: carbon monoxide 73.43%, hydrogen 17.52%, nitrogen 7.79%, carbon dioxide 0.92%, oxygen 0.33%; flow rate is 62256Nm 3 / h, pressure 0.75MPa, temperature 40℃.

[0167] CO+N2 logistics composition and output: carbon monoxide 81.61%, nitrogen 18.24%, carbon dioxide 0.07%; flow rate is 16242Nm 3 / h (725.08 kmol / h), pressure 0.5 MPa, temperature 40°C.

[0168] H2 logistics composition and output: hydrogen 99.99%, nitrogen 0.01%; flow rate 12292Nm 3 / h (548.74kmol / h), pressure of 2.5MPa, and temperature of 40℃.

[0169] Hydrogen composition and replenishment: 99.99% hydrogen, 0.01% nitrogen; flow rate is 13621Nm 3 / h (608.08 kmol / h), pressure of 2.5 MPa, and temperature of 40°C.

[0170] Ethylene glycol composition and output: 99.9% ethylene glycol, 0.1% methyl acetate; flow rate: 11,943 kg / h (192.63 kmol / h), pressure: 0.03 MPa, temperature: 40°C. Annual output: 100,324 tons (assuming 8,400 hours of operation), assuming a design capacity of 100,000 tons / year.

[0171] Based on the above embodiments, in general:

[0172] 1. The embodiments of the present invention utilize pressure swing adsorption decarbonization, combined with cooling liquefaction and distillation separation, to not only produce high-purity liquid carbon dioxide for direct use in oil recovery, storage, or chemical synthesis, but also to 100% recover the reducing components in blast furnace gas for blast furnace recycling and as a chemical raw material.

[0173] 2. The embodiments of the present invention can realize the carbon cycle of the oxygen blast furnace, that is, the decarbonized gas is recycled into the blast furnace, which can reduce the coke ratio and the amount of coal injected into the blast furnace, thereby reducing carbon emissions per ton of steel.

[0174] 3. The present invention utilizes surplus decarbonization gas from blast furnace, refined converter gas and converted coke oven gas through low-temperature methanol washing, temperature swing adsorption and two-stage pressure swing adsorption processes to separate CO+N2 and H2 for the synthesis of chemical product ethylene glycol.

[0175] 4. This invention enables steel companies to fully utilize the chemical energy of all three types of gas resources, eliminating the inefficient use of thermal energy. By utilizing surplus decarbonized gas, coke oven gas, and converter gas as raw materials for manufacturing chemical products, this approach achieves "carbon sequestration and emission reduction," while also increasing value and efficiency, significantly reducing primary energy consumption at the source.

[0176] 5. The present invention utilizes a synthesis gas source that is not produced through a coal gasification process, and uses carbon dioxide hydrogenation to produce methanol and catalytic coupling hydrogenation technology to produce ethylene glycol, which can save the cost of coal gasification process construction and gasification furnace and other equipment, effectively reduce the production cost of methanol and ethylene glycol, and make full use of renewable energy.

[0177] 6. The present invention utilizes this part of N2 in the mixed coal gas purification process without separating it from CO. This operation can not only avoid the cost of separating CO and N2 during the purification process, but also reduce the cost of reintroducing N2 gas in the DMO synthesis process, which can effectively reduce the production cost of ethylene glycol.

[0178] It should be noted that the near-zero carbon emission blast furnace long-process tempering co-production process system provided in the above-mentioned embodiment and the near-zero carbon emission blast furnace long-process tempering co-production process provided in the above-mentioned embodiment are based on the same concept. The specific manner in which each unit and system performs operations has been described in detail in the process embodiment and will not be repeated here. In actual applications of the near-zero carbon emission blast furnace long-process tempering co-production process system provided in the above-mentioned embodiment, the above-mentioned functions can be distributed to different systems and equipment as needed to complete all or part of the functions described above, and this is not limited here.

[0179] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A near-zero carbon emission blast furnace long-process tempering co-production process, characterized in that: The steps include: Decarburizing blast furnace gas by pressure swing adsorption to separate desorbed gas and decarburized gas; The desorbed gas is subjected to liquefaction and rectification purification 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 from light hydrocarbons to form a mixed gas; The mixed coal gas is washed with low-temperature methanol, subjected to temperature swing adsorption and two-stage pressure swing adsorption to separate into two streams for synthesizing ethylene glycol, wherein one stream includes CO and N2, and the other stream includes H2; The mixed coal gas after temperature swing adsorption treatment is separated into two streams by two-stage pressure swing adsorption, wherein the two-stage pressure swing adsorption includes stage I pressure swing adsorption and stage II pressure swing adsorption performed sequentially, the stream separated by stage I pressure swing adsorption includes CO and N2, and the stream separated by stage II pressure swing adsorption includes H2; The process of synthesizing ethylene glycol adopts catalytic coupling hydrogenation technology, including the following steps: Dimethyl oxalate is synthesized using methyl nitrite as raw material and a stream containing CO and N2 as raw gas and diluent; The dimethyl oxalate synthesized in the above steps is used to synthesize ethylene glycol using a stream containing H2 as raw gas.

2. The process according to claim 1, characterized in that: The liquid carbon dioxide is used for oil recovery, storage or as a raw material for synthesizing methanol; and / or, recycling 80% or more of the decarbonized gas to the blast furnace, and mixing 20% ​​or less of the decarbonized gas with refined converter gas and coke oven gas converted to light hydrocarbons to form a mixed gas; And / or, the non-condensable gas separated in the desorbed gas distillation process is recycled for cooling and then returned together with the blast furnace gas to undergo pressure swing adsorption decarbonization, and the reducing components are recovered again.

3. The process according to claim 1, characterized in that: The decarbonized gas and the refined converter gas are subjected to catalytic desulfurization and deoxidation purification, and then mixed with the coke oven gas that has been converted to light hydrocarbons to form a mixed gas.

4. The process according to claim 1, wherein: The process further comprises the steps of: The pre-treated blast furnace gas is subjected to pressure swing adsorption decarbonization. The converter gas produced as a by-product in the converter steelmaking process is pretreated to obtain the refined converter gas. The coke oven gas converted to light hydrocarbons is pre-treated and then mixed with decarbonized gas and refined converter gas to form a mixed gas; The pretreatment process includes at least one of dust removal, cooling, desulfurization and pressurization.

5. The process according to claim 1, characterized in that: Before the low-temperature methanol washing, the decarbonized gas, refined converter gas, and coke oven gas converted to light hydrocarbons in the mixed gas all meet at least one of the following conditions (a) to (d): (a) Temperature is less than or equal to 40°C; (b) oxygen content is less than or equal to 50 ppm; (c) The hydrogen sulfide content is less than or equal to 0.1 ppm; (d) The pressure is 2.0~3.5MPa.

6. The process according to claim 1, characterized in that: The mixed coal gas after low-temperature methanol washing includes H2, CO, N2 and other impurities. The requirements for the concentration of other impurities include: methanol ≤ 20 ppm, CO2 ≤ 20 ppm, sulfide ≤ 0.1 ppm, oxygen ≤ 50 ppm; And / or, during the low-temperature methanol washing process, the methanol that absorbs impurities is recycled after methanol recovery treatment and returned to the low-temperature methanol washing for recycling, and the separated impurities hydrogen sulfide and CO2 enter the desorption gas drying process for drying treatment, and then undergo deep-cold liquefaction and distillation together with the desorption gas.

7. The process according to claim 1, characterized in that: The mixed coal gas after the low-temperature methanol washing treatment is subjected to temperature swing adsorption to remove heavy impurity components, wherein the heavy impurity components include methanol and water.

8. The process according to claim 1, characterized in that: The process further comprises the following steps: during the process of synthesizing ethylene glycol, hydrogen is supplemented.

9. A near-zero carbon emission blast furnace long-process tempering co-production process system, characterized by: The process system includes: The first unit includes a pressure swing adsorption decarbonization system for separating blast furnace gas into desorbed gas and decarbonized gas, and a liquefaction and rectification purification system for liquefying and rectifying the desorbed gas to obtain liquid carbon dioxide; The second unit includes a catalytic desulfurization and deoxygenation system for catalytically desulfurizing and deoxidizing the decarbonized gas and the refined converter gas; A third unit, comprising a light hydrocarbon conversion system for converting coke oven gas into light hydrocarbons; A fourth unit includes a coal gas mixing system, a low-temperature methanol washing system, a temperature swing adsorption system, and a two-stage pressure swing adsorption system, which are arranged in sequence according to the process flow. The coal gas mixing system is connected to the pressure swing adsorption decarbonization system and the light hydrocarbon conversion system, and is used to mix the decarbonized gas, the refined converter gas, and the coke oven gas converted to light hydrocarbons to form a mixed coal gas. The low-temperature methanol washing system, the temperature swing adsorption system, and the two-stage pressure swing adsorption system are used to perform low-temperature methanol washing, temperature swing adsorption, and two-stage pressure swing adsorption on the mixed coal gas in sequence to separate two streams for synthesizing ethylene glycol, one of which includes CO and N2, and the other includes H2; The two-stage pressure swing adsorption system includes a stage I pressure swing adsorption device and a stage II pressure swing adsorption device, which are arranged in sequence according to the process flow. The stage I pressure swing adsorption device is used to perform stage I pressure swing adsorption on the mixed coal gas after the temperature swing adsorption treatment to separate the flow including CO and N2. The stage II pressure swing adsorption device is used to perform stage II pressure swing adsorption on the mixed coal gas after the stage I pressure swing adsorption treatment to separate the flow including H2. The process system also includes a dimethyl oxalate synthesis unit and an ethylene glycol synthesis unit. The dimethyl oxalate synthesis unit is connected to a two-stage pressure swing adsorption system and is used to synthesize dimethyl oxalate using a logistics including CO and N2 as raw gas; the ethylene glycol synthesis unit is connected to the dimethyl oxalate synthesis unit and the two-stage pressure swing adsorption system and is used to synthesize ethylene glycol using dimethyl oxalate synthesized in the dimethyl oxalate synthesis unit as raw material and a logistics including H2 as raw gas.

10. The process system according to claim 9, characterized in that: The process system includes at least one of the following units, systems or equipment (1) to (9): (1) The liquefaction distillation purification system includes a liquid carbon dioxide outlet, and the process system also includes a methanol synthesis unit, which is connected to the liquid carbon dioxide outlet; (2) The pressure swing adsorption decarbonization system includes a decarbonization gas outlet end, and the decarbonization gas outlet end is connected to the blast furnace reducing gas inlet end; (3) The liquefied distillation purification system includes a distillation device and a precooler. The distillation device includes a non-condensable gas outlet end, and the non-condensable gas outlet end is connected to the precooler. The precooler uses non-condensable gas as a cold source. The precooler includes a cold source outlet end, and the cold source outlet end is connected to the air inlet end of the pressure swing adsorption decarbonization system. (4) The first unit further includes a first pretreatment system for pretreating blast furnace gas discharged from the blast furnace; (5) The process system further includes a second unit, which includes a second pretreatment system for pretreating converter gas produced as a by-product in the converter steelmaking process to obtain refined converter gas; (6) The third unit further includes a third pretreatment system disposed after the light hydrocarbon conversion system for pretreating the coke oven gas converted to light hydrocarbons; (7) The gas mixing system includes a pressurizing device for pressurizing the mixed gas; (8) The fourth unit also includes a methanol recovery system for recovering the methanol that absorbs impurities during the low-temperature methanol washing process; the liquefaction distillation purification system includes a drying device for drying the desorbed gas, and the methanol recovery system is connected to the drying device to feed the impurities hydrogen sulfide and CO2 separated by the methanol recovery process into the drying device; (9) The process system further includes a hydrogen replenishing unit, which is used to replenish hydrogen during the process of synthesizing ethylene glycol.

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