Process method for CO purification by desulfurization and decarburization of blast furnace gas.

Abstract

This invention provides a process method for CO purification by desulfurization and decarburization of blast furnace gas, which has advantages such as achieving highly efficient desulfurization and decarburization and significantly reducing energy consumption. [Solution] The method includes the steps of introducing blast furnace gas into a pretreatment device for cooling, dehydration, dechlorination, and dust removal; sequentially introducing a decarburization and desulfurization adsorption device consisting of three stages (one, two, and three) filled with a large particle adsorbent to perform decarburization and desulfurization treatment to remove carbon dioxide, hydrogen sulfide, and carbonyl sulfide from the gas, wherein the third stage decarburization and desulfurization is performed by spraying unsalted water, the second stage decarburization and desulfurization is performed by spraying ammonia water, and the first stage decarburization and desulfurization is performed by spraying low-carbon ammonia water; and performing variable pressure adsorption on the blast furnace gas after decarburization and desulfurization treatment to obtain high-concentration CO gas. The method utilizes the adsorption and flow guidance action of the large granular adsorbent loaded into the adsorption device to improve the removal rate of ammonia from sulfur species and carbon dioxide in the blast furnace gas, while simultaneously producing ammonium bicarbonate.

Description

Technical Field

[0001] The present invention relates to the technical fields of energy conservation and carbon emission reduction in the steel industry and the cogeneration technology of steel and chemistry. Specifically, it relates to a process method for purifying CO by desulfurizing and decarbonizing blast furnace gas.

Background Art

[0002] According to statistics, the steel industry in our country is the industry with the largest carbon emissions in the manufacturing industry, accounting for about 15% of the total carbon emissions in our country. In response to the goals that each industry in the country is trying to achieve, the steel industry is working hard to save energy and reduce carbon emissions. The blast furnace gas in the steel industry is mainly used as fuel gas for regenerative hot blast furnaces, power generation, mixed with coke oven gas or converter gas for fuel gas in processes such as rolling, etc. The added value generated is low, and it belongs to fuels with high carbon emissions. Therefore, how to comprehensively utilize blast furnace gas with high added value and reduce steel production costs has always been an important issue that steel enterprises pay attention to. Chinese Utility Model Publication CN221051806U discloses that by combining an activated carbon adsorption desulfurization and deacidification system and an organic amine absorption and capture carbon dioxide system, desulfurization of blast furnace gas and emission reduction by carbon dioxide capture are realized, and at the same time, blast furnace gas with high calorific value is obtained, achieving the purpose of treating blast furnace gas with low cost, high efficiency, and low energy consumption. Chinese Patent Publication Gazette CN115196590A discloses a process that is economical and reasonable, with a simple process and is feasible to collect hot blast furnace coal gas and simultaneously produce hydrogen. Chinese Utility Model Publication CN221822122U discloses a system that produces methanol and acetate with hot blast furnace gas and coke oven gas to co-produce LNG, and can maximize the resource-based comprehensive utilization of various effective components in the gas of the steelworks, etc. However, all of the above technologies have technical means with high energy consumption, such as compressing blast furnace gas or using organic amines to adsorb carbon dioxide. How to decarbonize gas with low energy consumption and simultaneously produce CO gas as a by-product remains a difficult problem to be solved currently.

Summary of the Invention

[0003] In response to the problems present in the carbon reduction technology of the steel mills mentioned above, the present invention discloses a CO purification process method by desulfurization and decarburization of blast furnace gas. By loading a multi-stage, multi-layered large particle adsorbent into the adsorption tower, the adsorption and flow guidance effects of the large particle adsorbent are utilized to improve the residence time of acidic gases in the blast furnace gas in the adsorption tower, thereby effectively promoting the reaction between ammonia and acidic gases, improving the removal rate of ammonia from sulfur species and carbon dioxide in the blast furnace gas, and simultaneously generating ammonium bicarbonate, thereby achieving true desulfurization and decarburization requirements. Subsequently, the CO concentration is increased using variable pressure adsorption, and the high-concentration CO can be used as a raw material for other chemical industrial synthesis, thus realizing high value-added utilization of blast furnace gas. [Means for solving the problem]

[0004] The present invention employs the following technical solutions. A process method for purifying CO by desulfurization and decarburization of blast furnace gas, comprising the following steps: Step S1 involves introducing blast furnace gas into a pretreatment device to perform low-temperature dehydration, dust removal, and chlorine removal. The pre-treated blast furnace gas is sequentially introduced into a one-stage decarburization and desulfurization adsorption unit, a two-stage decarburization and desulfurization adsorption unit, and a three-stage decarburization and desulfurization adsorption unit, all of which are filled with a large particle adsorbent, to perform decarburization and desulfurization treatment, thereby removing carbon dioxide, hydrogen sulfide, and carbonyl sulfide from the blast furnace gas. In step S2, the three-stage decarburization and desulfurization adsorption unit is sprayed with saline-free water, the two-stage decarburization and desulfurization adsorption unit is sprayed with ammonia water at a certain concentration, and the one-stage decarburization and desulfurization adsorption unit is sprayed with low-carbon ammonia water at a certain concentration. The process includes step S3, in which CO and nitrogen are separated from the blast furnace gas after decarburization and desulfurization treatment using a pressure fluctuation adsorption CO purification device, thereby purifying high-concentration CO gas.

[0005] In step S1, the pretreatment device performs dehydration, dechlorination, and dust removal from the blast furnace gas using a low-temperature cooling water method, simultaneously removing water, chloride ions, and dust. A drain port is provided at the bottom of the pretreatment device, and the blast furnace gas temperature after the cooling treatment is lower than 15°C.

[0006] The aforementioned temperature is 0-5°C.

[0007] In step S1, a cooling water inlet is provided below the side wall of the pretreatment device, and a hot water outlet is provided above the side wall. Cooling energy is supplied to the heat exchange of the blast furnace gas through the cooling water inlet, and the hot water after heat exchange is discharged from the hot water outlet.

[0008] Each of the decarburization and desulfurization adsorption devices described in step S2 is filled with three layers of solid spheres, hollow spheres, or pebble-shaped large particle adsorbents of different diameters, and the adsorbents have the function of simultaneously adsorbing carbon dioxide, hydrogen sulfide, and carbonyl sulfide. Blast furnace gas is supplied from the bottom of the side wall of each of the decarburization and desulfurization adsorption devices and discharged from the top of the side wall of each of the decarburization and desulfurization devices.

[0009] Preferably, the three layers of adsorbents in each stage of the decarburization and desulfurization adsorption apparatus are as follows: the diameter of the adsorbent packed in the upper layer is 40 to 50 mm, the diameter of the adsorbent packed in the middle layer is 30 to 40 mm, and the diameter of the adsorbent packed in the lower layer is 20 to 30 mm.

[0010] Preferably, the adsorbent in step S2 is a composite porous adsorbent made from a composite of one or more of the following raw materials: carbon nitride, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, zirconium oxide, and cerium oxide, which is molded and then sintered at 700 to 900°C.

[0011] The spray liquid used in the three-stage decarburization and desulfurization adsorption apparatus in step S2 is saline water. The liquid after the spray treatment of the three-stage decarburization and desulfurization adsorption apparatus is mixed with liquid ammonia added from an external source to form the spray liquid required for the two-stage decarburization and desulfurization adsorption apparatus, which is a mixture of ammonia water with a concentration of 15% to 17% and ammonium carbonate with a concentration of less than 0.1%. The liquid obtained after spray treatment in the aforementioned two-stage decarburization and desulfurization adsorption apparatus is used as the spray liquid required for the aforementioned one-stage decarburization and desulfurization adsorption apparatus, and this liquid is a mixture of aqueous ammonia with a concentration of 10% to 15%, ammonium carbonate with a concentration of less than 5%, and ammonium bicarbonate with a concentration of less than 1%. After undergoing the spray treatment of the aforementioned one-stage decarburization and desulfurization adsorption apparatus, the liquid discharged from the bottom of the apparatus is a mixture of ammonium bicarbonate with a concentration of 15-20% and ammonium carbonate with a concentration of less than 1%.

[0012] Preferably, a first spray liquid inlet for introducing spray liquid is provided at the top of the one-stage decarburization and desulfurization adsorption apparatus, and a first drain port for discharging spray liquid is provided at the bottom thereof. A second spray liquid inlet for introducing spray liquid is provided at the top of the two-stage decarburization and desulfurization adsorption apparatus, and a second drain port for discharging spray liquid is provided at the bottom thereof. A third spray liquid inlet for introducing spray liquid is provided at the top of the three-stage decarburization and desulfurization adsorption apparatus, and a third drain port for discharging spray liquid is provided at the bottom thereof.

[0013] In step S3, after the decarburization and desulfurization treatment, the sulfur content in the blast furnace gas is less than 5 ppm, and the carbon dioxide content is less than 0.5%. The CO gas concentration after pressure fluctuation adsorption separation by the pressure fluctuation adsorption CO purification apparatus (5) is higher than 98.5%. [Effects of the Invention]

[0014] The technical solution of the present invention has the following advantages. A. The present invention effectively improves the residence time of acidic gases in blast furnace gas within a decarburization / desulfurization adsorption unit by using a multi-stage, multi-layered large particle adsorbent, thereby significantly improving the reaction efficiency of ammonia with sulfur species and carbon dioxide, and achieving highly efficient desulfurization and decarburization. This innovation not only meets the requirements of environmental protection but also creates favorable conditions for the subsequent CO purification step.

[0015] B. Compared to conventional technologies, the process method of the present invention avoids energy-intensive methods such as compression or adsorption using organic amines. Through clever design, the entire desulfurization and decarburization process is carried out at low temperatures and atmospheric pressure, significantly reducing energy consumption and meeting the current urgent needs for energy conservation and emission reduction.

[0016] In addition to desulfurization and decarburization, this invention can also simultaneously produce ammonium bicarbonate, which not only further improves the overall utilization rate of resources but also brings additional economic benefits to businesses. This integrated production method is eco-friendly, economical, and has broad market prospects.

[0017] D. Through a subsequent variable pressure adsorption step, the present invention can purify high-concentration CO gas. The high-value-added carbon dioxide can be directly used as a chemical material and is used in the synthesis of chemicals such as methyl alcohol and acetate, thereby further improving the utilization value of blast furnace gas. [Brief explanation of the drawing]

[0018] To more clearly describe specific embodiments of the present invention, the accompanying drawings that may be used in specific embodiments are briefly described below. However, the accompanying drawings in the following description are only a part of embodiments of the present invention, and it will be obvious to those skilled in the art that other accompanying drawings can be obtained based on these drawings without requiring any creative effort.

[0019] [Figure 1] This is a schematic diagram of the overall structure of the process system for CO purification by desulfurization and decarburization of blast furnace gas according to the present invention.

Best Mode for Carrying Out the Invention

[0020] Next, in conjunction with the drawings, the technical solution of the present invention will be clearly and completely described. The described embodiments are clearly some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] Example 1 As shown in FIG. 1, this example provides a process method for CO purification by desulfurization and decarbonization of blast furnace gas, including the following steps. Introduce blast furnace gas at 5000 Nm 3 / h and 60°C into the pretreatment device 1 for dehydration, dust removal, and dechlorination treatment, and the temperature of the blast furnace gas after pretreatment is 9°C in step S1. Introduce the blast furnace gas after pretreatment into the desulfurization and decarbonization adsorption devices in three stages in sequence. The three layers of adsorbents in each stage of the device are as follows: The upper layer is filled with hollow spherical alumina adsorbents with a diameter of 40 - 50 mm, the middle layer is filled with jade-like magnesia adsorbents with a diameter of 30 - 40 mm, and the lower layer is filled with composite adsorbents composed of spherical alumina and magnesia with a diameter of 20 - 30 mm. All the above adsorbents are calcined in air at 700°C for 12 hours. The three-stage decarbonization and desulfurization adsorption device 4 is sprayed with deionized water. After mixing the sprayed liquid after treatment with liquid ammonia, it is used as the sprayed liquid required for the two-stage decarbonization and desulfurization adsorption device, and its content is a mixed solution of 15% aqueous ammonia and 0.03% ammonium carbonate. The sprayed liquid after treatment in the secondary decarbonization and desulfurization adsorption device 3 is a mixed solution of 11% aqueous ammonia, 3% ammonium carbonate, and 0.3% ammonium bicarbonate. The solution discharged from the bottom of the primary decarbonization and desulfurization adsorption device 2 is a mixed solution of 20% ammonium bicarbonate and 0.5% ammonium carbonate. The blast furnace gas经过三段脱硫脱碳处理后 contains 5% water, 0.3% carbon dioxide, 31% carbon monoxide, 63% nitrogen, the concentration of COS is 3 ppm, and hydrogen sulfide gas is not detected in step S2. Finally, introducing the blast furnace gas into the pressure swing adsorption CO purification device 5 for pressure swing adsorption treatment to purify CO, and obtaining 98.9% CO gas in step S3.

[0022] Example 2 This example provides a process method for purifying CO by desulfurization and decarbonization of blast furnace gas, including the following steps. Introducing blast furnace gas at 12000 Nm 3 / h and 70 °C into the pretreatment device 1 for dehydration, dust removal, and dechlorination treatment, and the temperature of the pretreated blast furnace gas is 14 °C in step S1. Passing the pretreated blast furnace gas through three-stage desulfurization and decarbonization adsorption devices in sequence. The three-layer adsorbents in each stage of the device are as follows: filling the upper layer with hollow spherical zirconia adsorbents with a diameter of 40 - 50 mm, filling the middle layer with jade-like silica adsorbents with a diameter of 30 - 40 mm, and filling the lower layer with composite adsorbents composed of spherical zirconia and silica with a diameter of 20 - 30 mm. All the above adsorbents are calcined in air at 800 °C for 10 hours. The three-stage decarbonization and desulfurization adsorption device 4 is sprayed with deionized water. After mixing the sprayed liquid after treatment and liquid ammonia, it is used as the sprayed liquid required for two-stage desulfurization and decarbonization, and its content is a mixed solution of 16% aqueous ammonia and 0.02% ammonium carbonate. The sprayed liquid after treatment in the two-stage decarbonization and desulfurization adsorption device 3 is a mixed solution of 10% aqueous ammonia, 5% ammonium carbonate, and 0.1% ammonium bicarbonate. The solution coming out from the bottom of the one-stage decarbonization and desulfurization adsorption device 2 is a mixed solution of 15% ammonium bicarbonate and 0.3% ammonium carbonate. The blast furnace gas treated by three-stage desulfurization and decarbonization contains 6% water, 0.4% carbon dioxide, 32% carbon monoxide, 61% nitrogen, the concentration of COS is 2 ppm, and hydrogen sulfide gas is not detected in step S2. Finally, introducing the blast furnace gas into the pressure swing adsorption CO purification device 5 for pressure swing adsorption treatment to purify CO, and obtaining 99.1% CO gas in step S3.

[0023] Example 3 This example provides a process method for purifying CO by desulfurization and decarbonization of blast furnace gas, including the following steps. Introducing blast furnace gas at 30000 Nm 3Step S1 involves introducing blast furnace gas at 50°C per hour into pretreatment device 1 to perform dehydration, dust removal, and chlorine removal, resulting in a blast furnace gas temperature of 12°C after pretreatment. The pre-treated blast furnace gas is passed sequentially through three stages of desulfurization and decarburization adsorption units. The three layers of adsorbents in each stage of the unit are as follows: the upper layer is filled with a hollow spherical composite adsorbent of ceria and zirconia with a diameter of 40-50 mm; the middle layer is filled with a pebble-shaped composite adsorbent of titanium oxide and magnesia with a diameter of 30-40 mm; and the lower layer is filled with a spherical composite adsorbent of alumina and silica with a diameter of 20-30 mm. All of the above adsorbents are calcined in air at 900°C for 5 hours. The three-stage desulfurization and decarburization adsorption unit 4 is sprayed with saline water. The spray liquid after treatment is mixed with liquid ammonia to create the spray liquid necessary for the second stage of desulfurization and decarburization, which is a mixture of 17% aqueous ammonia and 0.05% ammonium carbonate. The spray liquid after treatment in the secondary desulfurization and decarburization adsorption unit 3 is a mixture of 15% aqueous ammonia, 1% ammonium carbonate, and 0.2% ammonium bicarbonate. The solution discharged from the bottom of the primary decarburization and desulfurization adsorption unit 2 is a mixture of 18% ammonium bicarbonate and 0.4% ammonium carbonate. The blast furnace gas that underwent three-stage desulfurization and decarburization treatment contains 5% water, 0.5% carbon dioxide, 30% carbon monoxide, and 64% nitrogen, with a COS concentration of 1 ppm, and no hydrogen sulfide gas detected (Step S2). The process includes step S3, which involves introducing blast furnace gas into a variable pressure adsorption CO purification apparatus 5 and performing variable pressure adsorption treatment to purify CO and obtain 98.8% CO gas.

[0024] This invention utilizes the adsorption and flow guidance properties of a multi-stage, multi-layer, large-granule adsorbent to load a decarburization and desulfurization adsorption apparatus. This improves the removal rate of ammonia from sulfur species and carbon dioxide in blast furnace gas, while simultaneously producing ammonium bicarbonate, thus achieving true desulfurization and decarburization requirements. The desulfurization and decarburization process in this apparatus does not involve heating and pressurizing means, significantly reducing energy consumption and simplifying the process. By utilizing variable pressure adsorption, the CO concentration is increased, allowing the high-concentration CO to be used in other chemical industrial synthesis processes, thus realizing high-value-added utilization of blast furnace gas.

[0025] Any aspects not described in this invention apply to the prior art.

[0026] Clearly, the embodiments described above are not intended to limit the scope of implementation, but are merely illustrative examples. Those skilled in the art can make other variations or modifications based on the above description. It is not necessary, and impossible, to list all embodiments exhaustively. However, obvious changes or modifications still fall within the scope of protection of the present invention. [Explanation of symbols]

[0027] 1. Pre-treatment device 11 Drain 12 Cooling water inlet 13 Hot water outlet 2 Single stage decarburization desulfurization adsorption equipment 21 First spray liquid inlet 22 First drain port 3 Two-stage decarburization desulfurization adsorption equipment 31 Second spray liquid inlet 32 Second drain port 4 Three-stage decarburization and desulfurization adsorption equipment 41 Third spray liquid inlet 42 Third drain port 5. Variable Pressure Adsorption Purification CO System 6. Ammonia water tank 7. Low-carbon ammonia water tank 8. High-carbon ammonia water tank

Claims

1. A process method for purifying CO by desulfurization and decarburization of blast furnace gas, comprising the following steps: Step S1 involves introducing blast furnace gas into a pretreatment device (1) to perform low-temperature dehydration, dust removal, and chlorine removal. The pre-treated blast furnace gas is passed sequentially through a one-stage decarburization and desulfurization adsorption unit (2) filled with a large particle adsorbent, a two-stage decarburization and desulfurization adsorption unit (3), and a three-stage decarburization and desulfurization adsorption unit (4) to perform decarburization and desulfurization treatment, thereby removing carbon dioxide, hydrogen sulfide, and carbonyl sulfide from the blast furnace gas. In step S2, the three-stage decarburization and desulfurization adsorption unit (4) is sprayed with saline water, the two-stage decarburization and desulfurization adsorption unit (3) is sprayed with ammonia water at a certain concentration, and the one-stage decarburization and desulfurization adsorption unit (2) is sprayed with low-carbon ammonia water at a certain concentration. Each stage of the decarbonization and desulfurization adsorption apparatus described in step S2 is filled with three layers of solid spheres, hollow spheres, or pebble-shaped large particle adsorbents of different diameters, and the adsorbents have the function of simultaneously adsorbing carbon dioxide, hydrogen sulfide, and carbonyl sulfide. Blast furnace gas is supplied from the bottom of the side wall of each stage of the decarbonization and desulfurization adsorption apparatus and discharged from the top of the side wall of each stage of the decarbonization and desulfurization apparatus. The three layers of adsorbent in the decarburization and desulfurization adsorption apparatus described above are as follows: the diameter of the adsorbent packed in the upper layer is 40 to 50 mm, the diameter of the adsorbent packed in the middle layer is 30 to 40 mm, and the diameter of the adsorbent packed in the lower layer is 20 to 30 mm. The adsorbent in step S2 is a composite porous adsorbent made from a composite of one or more of the following raw materials: carbon nitride, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, zirconium oxide, and cerium oxide, which is molded and then sintered at 700 to 900°C. A process method for purifying CO by desulfurization and decarburization of blast furnace gas, characterized by comprising step S3, which involves separating CO and nitrogen from the blast furnace gas after decarburization and desulfurization treatment using a pressure fluctuation adsorption CO purification device (5) to purify high-concentration CO gas.

2. The process method for CO purification by desulfurization and decarburization of blast furnace gas according to claim 1, characterized in that the pretreatment device (1) in step S1 performs dehydration, dechlorination, and dust removal on the blast furnace gas using a low-temperature cooling water cooling method to simultaneously remove water, chloride ions, and dust, a drain port (11) is provided at the bottom of the pretreatment device (1), and the temperature of the blast furnace gas after the cooling treatment is lower than 15°C.

3. The process method for CO purification by desulfurization and decarburization of blast furnace gas according to claim 2, characterized in that the temperature is 0 to 5°C.

4. The process method for CO purification by desulfurization and decarburization of blast furnace gas according to claim 1, characterized in that a cooling water inlet (12) is provided below the side wall of the pretreatment device (1) in step S1, a hot water outlet (13) is provided above the side wall, cooling energy is provided for heat exchange of blast furnace gas via the cooling water inlet (12), and the hot water after heat exchange is discharged from the hot water outlet (13).

5. The spray liquid used in the three-stage decarburization and desulfurization adsorption apparatus (4) in step S2 is saline water, and the liquid after the spray treatment in the three-stage decarburization and desulfurization adsorption apparatus (4) is mixed with liquid ammonia added from an external source to become the spray liquid required for the two-stage decarburization and desulfurization adsorption apparatus (3), which is a mixture of ammonia water with a concentration of 15% to 17% and ammonium carbonate with a concentration of less than 0.1%. The liquid obtained after spray treatment in the two-stage decarburization and desulfurization adsorption apparatus (3) is used as the spray liquid required for the one-stage decarburization and desulfurization adsorption apparatus (2), and is a mixture of ammonia water with a concentration of 10% to 15%, ammonium carbonate with a concentration of less than 5%, and ammonium bicarbonate with a concentration of less than 1%. The process method for CO purification by desulfurization and decarburization of blast furnace gas according to claim 1, characterized in that, after the spray treatment of the one-stage decarburization and desulfurization adsorption apparatus (2), the liquid discharged from the bottom of the one-stage decarburization and desulfurization adsorption apparatus (2) is a mixture of ammonium bicarbonate with a concentration of 15-20% and ammonium carbonate with a concentration of less than 1%.

6. A first spray liquid inlet (21) for introducing spray liquid is provided at the top of the aforementioned one-stage decarburization and desulfurization adsorption apparatus (2), and a first drain port (22) for discharging spray liquid is provided at the bottom thereof. A second spray liquid inlet (31) for introducing spray liquid is provided at the top of the two-stage decarburization desulfurization adsorption apparatus (3), and a second drain port (32) for discharging spray liquid is provided at the bottom thereof. The process method for CO purification by desulfurization and decarburization of blast furnace gas according to claim 5, characterized in that a third spray liquid inlet (41) for introducing spray liquid is provided at the top of the three-stage decarburization and desulfurization adsorption apparatus (4), and a third drain outlet (42) for discharging spray liquid is provided at the bottom thereof.

7. In step S3, after the decarburization and desulfurization treatment, the sulfur content in the blast furnace gas is less than 5 ppm, and the carbon dioxide content is less than 0.5%. The process method for purifying CO by desulfurization and decarburization of blast furnace gas according to claim 1, characterized in that the CO gas concentration after pressure fluctuation adsorption separation by the pressure fluctuation adsorption CO purification apparatus (5) is higher than 98.5%.

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