A process for desulfurizing, decarbonizing and purifying CO from blast furnace gas

Abstract

The present invention discloses a process for desulfurizing, decarbonizing, and purifying CO from blast furnace gas, comprising the following steps: S1. Passing the blast furnace gas through a pretreatment device for cooling, dehydration, dechlorination, and dust removal; S2. Passing the gas through first, second, and third-stage decarbonization and desulfurization adsorption devices filled with large-particle adsorbents for decarbonization and desulfurization to remove carbon dioxide, hydrogen sulfide, and carbonyl sulfide from the gas. The third-stage decarbonization and desulfurization process sprays salt-free water, the second-stage decarbonization and desulfurization process sprays ammonia water, and the first-stage decarbonization and desulfurization process sprays low-carbonized ammonia water; S3. Subjecting the decarbonization and desulfurization-treated blast furnace gas to pressure swing adsorption to obtain high-concentration CO gas. By filling the adsorption devices with multi-stage, multi-layered large-particle adsorbents, the present invention utilizes the adsorption and flow-guiding properties of the large-particle adsorbents to increase the removal rate of sulfur species and carbon dioxide from the blast furnace gas with ammonia, while simultaneously co-producing ammonium bicarbonate to achieve true desulfurization and decarbonization requirements. High-concentration CO is obtained through pressure swing adsorption, thereby achieving high-value-added utilization of blast furnace gas.

Description

Technical Field

[0001] The present invention relates to the fields of energy conservation and emission reduction technology and steelmaking co-production technology in the steel industry, and in particular to a process for desulfurizing, decarbonizing and purifying CO in blast furnace gas. Background Art

[0002] According to statistics, my country's steel industry is the highest carbon emitter among manufacturing industries, accounting for approximately 15% of my country's total carbon emissions. Faced with national targets for various industries to achieve, the steel industry is actively seeking ways to conserve energy and reduce carbon emissions. Blast furnace gas in the steel industry is primarily used as fuel for regenerative hot blast furnaces, for power generation, and as a fuel for processes such as steel rolling, mixed with coke oven gas or converter gas. This generates relatively low added value and is a high-carbon emission fuel. Therefore, how to achieve high-value-added comprehensive utilization of blast furnace gas to reduce steel production costs has long been a major concern for steel companies. CN221051806U discloses coupling an activated carbon adsorption desulfurization and deacidification system with an organic amine absorption and capture system for carbon dioxide, achieving refined desulfurization and carbon dioxide capture and emission reduction of blast furnace gas. This simultaneously produces high-calorific-value blast furnace gas, achieving the goal of low-cost, high-efficiency, and low-energy blast furnace gas treatment. CN 115196590A discloses an economically sound, simple, and feasible process for carbon capture and hydrogen co-production from blast furnace gas; CN 221822122U discloses a system for producing methanol and acetic acid from blast furnace gas and coke oven gas to produce LNG, maximizing the resource utilization of multiple active components in steel mill gas. However, all of these technologies involve high energy consumption, such as compressing blast furnace gas or using organic amines to absorb carbon dioxide. Therefore, achieving low-energy carbon removal from the gas while simultaneously reducing the by-product of CO remains a challenge. Summary of the Invention

[0003] In response to the problems existing in the carbon reduction technology of the above-mentioned steel plant, the present invention discloses a process method for desulfurization, decarbonization and purification of CO in blast furnace gas. By filling an adsorption tower with multi-stage, multi-layered large-particle adsorbent, the adsorption and diversion effects of the large-particle adsorbent are utilized to increase the residence time of acid gases in the blast furnace gas in the adsorption tower, thereby effectively promoting the reaction between ammonia and acid gases, and improving the removal rate of sulfur species and carbon dioxide in the blast furnace gas by ammonia. At the same time, ammonium bicarbonate is co-produced to achieve true desulfurization and decarbonization requirements. Then, the concentration of CO is increased by pressure swing adsorption, and the high-concentration CO is used as a raw material for other chemical synthesis, thereby realizing high added value utilization of the blast furnace gas.

[0004] The present invention adopts the following technical solutions:

[0005] A process for desulfurizing, decarbonizing and purifying CO from blast furnace gas comprises the following steps:

[0006] S1. Blast furnace gas is passed into a pretreatment device for low-temperature dehydration, dust removal and dechlorination;

[0007] S2. The pretreated blast furnace gas is sequentially passed through a primary decarbonization and desulfurization adsorption device, a secondary decarbonization and desulfurization adsorption device, and a tertiary decarbonization and desulfurization adsorption device filled with large-particle adsorbents for decarbonization and desulfurization treatment to remove carbon dioxide, hydrogen sulfide, and carbonyl sulfide from the blast furnace gas. The tertiary decarbonization and desulfurization adsorption device is sprayed with salt-free water, the secondary decarbonization and desulfurization adsorption device is sprayed with a certain concentration of ammonia water, and the primary decarbonization and desulfurization adsorption device is sprayed with a certain concentration of low-carbonized ammonia water;

[0008] S3. The blast furnace gas after decarbonization and desulfurization is subjected to a pressure swing adsorption CO purification device to separate CO and nitrogen and purify high-concentration CO gas.

[0009] The pretreatment device in step S1 dehydrates, dechlorinates and removes dust from the blast furnace gas by using a low-temperature chilled water cooling method to remove water, chloride ions and dust. A water outlet is provided at the bottom of the pretreatment device, and the temperature of the blast furnace gas after cooling treatment is lower than 15°C.

[0010] The low temperature is 0-5°C.

[0011] In step S1, a chilled water inlet is provided below the side wall of the pretreatment device, and a warm water outlet is provided above the side wall. The chilled water inlet provides cold energy for heat exchange of blast furnace gas, and the warm water after heat exchange is discharged from the warm water outlet.

[0012] Each stage of the decarbonization and desulfurization adsorption device described in step S2 is filled with three layers of solid balls, hollow balls or pebble-shaped large-particle adsorbents of different diameters. The adsorbents have the function of adsorbing carbon dioxide, hydrogen sulfide and carbonyl sulfide at the same time. The blast furnace gas is input from the bottom of the side wall of each stage of the decarbonization and desulfurization adsorption device and output from the top of the side wall of each stage of the decarbonization and desulfurization device.

[0013] Preferably, the three layers of adsorbent in each stage of the decarbonization and desulfurization adsorption device are as follows: the adsorbent filled in the upper layer has a diameter of 40-50 mm, the adsorbent filled in the middle layer has a diameter of 30-40 mm, and the adsorbent filled in the lower layer has a diameter of 20-30 mm.

[0014] Preferably, the adsorbent in step S2 is a composite porous adsorbent made of one or more composites of carbon nitride, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, zirconium oxide, and cerium oxide as raw materials, which is molded and then sintered at 700-900°C.

[0015] The spray liquid used for the three-stage decarbonization and desulfurization adsorption device in step S2 is salt-free water. The liquid after spraying treatment by the three-stage decarbonization and desulfurization adsorption device is mixed with liquid ammonia added from the outside and used as the spray liquid required for the two-stage decarbonization and desulfurization adsorption device, which is a mixture of ammonia water with a concentration of 15%-17% and ammonium carbonate with a concentration of less than 0.1%; the liquid after spraying treatment by the two-stage decarbonization and desulfurization adsorption device is used as the spray liquid required for the one-stage decarbonization and desulfurization adsorption device, which is a mixture of ammonia water with a concentration of 10%-15%, ammonium carbonate with a concentration of less than 5% and ammonium bicarbonate with a concentration of less than 1%; after spraying treatment by the one-stage decarbonization and desulfurization adsorption device, the liquid coming out from the bottom of the one-stage decarbonization and desulfurization adsorption device is a mixture of ammonium bicarbonate with a concentration of 15-20% and ammonium carbonate with a concentration of less than 1%.

[0016] Preferably, the top of the first-stage decarbonization and desulfurization adsorption device is provided with a first spray liquid inlet for introducing spray liquid, and the bottom thereof is provided with a first drain port for discharging the spray liquid; the top of the second-stage decarbonization and desulfurization adsorption device is provided with a second spray liquid inlet for introducing spray liquid, and the bottom thereof is provided with a second drain port for discharging the spray liquid; the top of the tertiary decarbonization and desulfurization adsorption device is provided with a third spray liquid inlet for introducing spray liquid, and the bottom thereof is provided with a third drain port for discharging the spray liquid.

[0017] The sulfur species content in the blast furnace gas after decarbonization and desulfurization treatment in step S3 is less than 5ppm, and the carbon dioxide content is less than 0.5%; the CO gas concentration after pressure swing adsorption separation by the pressure swing adsorption CO purification device is greater than 98.5%.

[0018] The technical solution of the present invention has the following advantages:

[0019] A. This invention utilizes multi-stage, multi-layered, large-particle adsorbents to effectively increase the residence time of acid gases in blast furnace gas within the decarbonization and desulfurization adsorption unit, significantly improving the reaction efficiency of ammonia with sulfur species and carbon dioxide, achieving highly efficient desulfurization and decarbonization. This innovative approach not only meets environmental requirements but also creates favorable conditions for subsequent CO purification steps.

[0020] B. Compared with existing technologies, the process of the present invention avoids high-energy consumption methods such as compression or organic amine adsorption. Through ingenious design, the entire desulfurization and decarbonization process is carried out at low temperature and normal pressure, greatly reducing energy consumption and meeting the current urgent needs of energy conservation and emission reduction.

[0021] C. While desulfurizing and decarbonizing, the present invention can also co-produce ammonium bicarbonate, which not only further improves the comprehensive utilization rate of resources but also brings additional economic benefits to the enterprise. This integrated production method is both environmentally friendly and economical, and has broad market prospects.

[0022] D. Through the subsequent pressure swing adsorption step, the present invention can purify high-concentration CO gas. This high-value-added CO gas can be directly used as a chemical raw material for synthesizing chemicals such as methanol and acetic acid, thereby further increasing the utilization value of blast furnace gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention, the following will briefly introduce the drawings required for use in the specific embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the overall structure of the process system for desulfurization, decarbonization and purification of CO from blast furnace gas in the present invention.

[0025] The following are marked in the figure:

[0026] 1-pretreatment device, 11-drain port, 12-chilled water inlet, 13-warm water outlet; 2-first-stage decarbonization and desulfurization adsorption device, 21-first spray liquid inlet, 22-first drainage port; 3-second-stage decarbonization and desulfurization adsorption device, 31-second spray liquid inlet, 32-second drainage port; 4-tertiary decarbonization and desulfurization adsorption device, 41-third spray liquid inlet, 42-third drainage port; 5-pressure swing adsorption CO purification device; 6-sleeping tank; 7-low-carbonized ammonia water tank; 8-high-carbonized ammonia water tank. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] Example 1

[0029] like Figure 1 As shown, this embodiment provides a process for desulfurizing, decarbonizing and purifying CO from blast furnace gas, comprising the following steps:

[0030] S1, 5000Nm 3 / h, 60 ℃ blast furnace gas is introduced into the pretreatment device 1 for dehydration, dust removal and chlorine removal. The temperature of the blast furnace gas after pretreatment is 9 ℃.

[0031] S2. The pretreated blast furnace gas is sequentially passed through three stages of desulfurization and decarbonization adsorption devices. Each stage contains three layers of adsorbent: an upper layer filled with hollow spherical alumina adsorbent with a diameter of 40-50 mm, a middle layer filled with pebble-shaped magnesium oxide adsorbent with a diameter of 30-40 mm, and a lower layer filled with a composite adsorbent composed of spherical alumina and magnesium oxide with a diameter of 20-30 mm. All of these adsorbents are calcined in air at 700°C for 12 hours. The third-stage decarbonization and desulfurization adsorption device (4) is sprayed with salt-free water. The treated spray liquid is mixed with liquid ammonia and used as the spray liquid for the second-stage desulfurization and decarbonization process. The spray liquid consists of a mixture of 15% aqueous ammonia and 0.03% ammonium carbonate. The spray liquid from the second-stage decarbonization and desulfurization adsorption device (3) is a mixture of 11% aqueous ammonia, 3% ammonium carbonate, and 0.3% ammonium bicarbonate. The solution exiting the bottom of the first-stage decarbonization and desulfurization adsorption device (2) is a mixture of 20% ammonium bicarbonate and 0.5% ammonium carbonate. The blast furnace gas after the three-stage desulfurization and decarbonization treatment contains 5% water, 0.3% carbon dioxide, 31% carbon monoxide and 63% nitrogen. The concentration of COS is 3 ppm and no hydrogen sulfide gas is detected.

[0032] S3. Finally, the blast furnace gas is passed into the pressure swing adsorption CO purification device 5 for pressure swing adsorption treatment to purify CO, thereby obtaining 98.9% CO gas.

[0033] Example 2

[0034] This embodiment provides a process for desulfurizing, decarbonizing and purifying CO from blast furnace gas, comprising the following steps:

[0035] S1, 12000Nm 3 / h, 70 ℃ blast furnace gas is introduced into the pretreatment device 1 for dehydration, dust removal and chlorine removal. The temperature of the blast furnace gas after pretreatment is 14 ℃.

[0036] S2. The pretreated blast furnace gas is sequentially passed through three stages of desulfurization and decarbonization adsorption devices. Each stage contains three layers of adsorbent: an upper layer filled with hollow spherical zirconium oxide adsorbent with a diameter of 40-50 mm, a middle layer filled with pebble-shaped silica adsorbent with a diameter of 30-40 mm, and a lower layer filled with a composite adsorbent composed of spherical zirconium oxide and silica with a diameter of 20-30 mm. All of these adsorbents are calcined in air at 800°C for 10 hours. The third-stage decarbonization and desulfurization adsorption device (4) is sprayed with salt-free water. The treated spray liquid is mixed with liquid ammonia and used as the spray liquid for the second-stage desulfurization and decarbonization process. The spray liquid consists of a mixture of 16% aqueous ammonia and 0.02% ammonium carbonate. The spray liquid from the second-stage decarbonization and desulfurization adsorption device (3) is a mixture of 10% aqueous ammonia, 5% ammonium carbonate, and 0.1% ammonium bicarbonate. The solution exiting the bottom of the first-stage decarbonization and desulfurization adsorption device (2) is a mixture of 15% ammonium bicarbonate and 0.3% ammonium carbonate. The blast furnace gas after the three-stage desulfurization and decarbonization treatment contains 6% water, 0.4% carbon dioxide, 32% carbon monoxide and 61% nitrogen. The concentration of COS is 2 ppm and no hydrogen sulfide gas is detected.

[0037] S3. Finally, the blast furnace gas is passed into the pressure swing adsorption CO purification device 5 for pressure swing adsorption treatment to purify CO, thereby obtaining 99.1% CO gas.

[0038] Example 3

[0039] This embodiment provides a process for desulfurizing, decarbonizing and purifying CO from blast furnace gas, comprising the following steps:

[0040] S1, first 30000Nm 3 / h, 50℃ blast furnace gas is introduced into the pretreatment device 1 for dehydration, dust removal and chlorine removal. The temperature of the blast furnace gas after pretreatment is 12℃.

[0041] S2. The pretreated blast furnace gas is sequentially passed through three stages of desulfurization and decarbonization adsorption devices. Each stage contains three layers of adsorbent: an upper layer filled with a composite adsorbent of hollow spheres of cerium oxide and zirconium oxide with a diameter of 40-50 mm; a middle layer filled with a composite adsorbent of pebble-shaped titanium oxide and magnesium oxide with a diameter of 30-40 mm; and a lower layer filled with a composite adsorbent of spheres of aluminum oxide and silicon oxide with a diameter of 20-30 mm. All of these adsorbents are calcined in air at 900°C for 5 hours. The third stage decarbonization and desulfurization adsorption device (4) is sprayed with salt-free water. The treated spray liquid is mixed with liquid ammonia and used as the spray liquid for the second stage desulfurization and decarbonization. The spray liquid contains a mixture of 17% aqueous ammonia and 0.05% ammonium carbonate. The spray liquid after treatment in the second stage decarbonization and desulfurization adsorption device (3) is a mixture of 15% aqueous ammonia, 1% ammonium carbonate, and 0.2% ammonium bicarbonate. The solution exiting the bottom of the primary decarbonization and desulfurization adsorption unit 2 is a mixture of 18% ammonium bicarbonate and 0.4% ammonium carbonate. Blast furnace gas treated with the tertiary desulfurization and decarbonization process contains 5% water, 0.5% carbon dioxide, 30% carbon monoxide, and 64% nitrogen. The COS concentration is 1 ppm, and no hydrogen sulfide gas is detected.

[0042] S3. Finally, the blast furnace gas is passed into the pressure swing adsorption CO purification device 5 for pressure swing adsorption treatment to purify CO, thereby obtaining 98.8% CO gas.

[0043] The present invention utilizes the adsorption and diversion effects of the large-particle adsorbents in a decarbonization and desulfurization adsorption device to increase the removal rate of sulfur species and carbon dioxide from blast furnace gas with ammonia, while simultaneously co-producing ammonium bicarbonate to achieve true desulfurization and decarbonization requirements. This process does not involve increasing temperature and pressure for desulfurization and decarbonization, significantly reducing energy consumption and simplifying the process. Pressure swing adsorption is used to increase the concentration of CO, which can then be used as a raw material for other chemical synthesis, thereby achieving high-value-added utilization of blast furnace gas.

[0044] Any matters not described in the present invention are applicable to the prior art.

[0045] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A process for desulfurizing, decarbonizing and purifying CO from blast furnace gas, characterized in that: The following steps are involved: S1, passing blast furnace gas into a pretreatment device (1) for low-temperature dehydration, dust removal and dechlorination; S2. The blast furnace gas after pretreatment is sequentially passed into a first-stage decarbonization and desulfurization adsorption device (2), a second-stage decarbonization and desulfurization adsorption device (3), and a third-stage decarbonization and desulfurization adsorption device (4) filled with large-particle adsorbent for decarbonization and desulfurization treatment to remove carbon dioxide, hydrogen sulfide, and carbonyl sulfide in the blast furnace gas. The third-stage decarbonization and desulfurization adsorption device (4) is sprayed with salt-free water, the second-stage decarbonization and desulfurization adsorption device (3) is sprayed with a certain concentration of ammonia water, and the first-stage decarbonization and desulfurization adsorption device (2) is sprayed with a certain concentration of low-carbonized ammonia water; Each stage of the decarbonization and desulfurization adsorption device in step S2 is filled with three layers of solid balls, hollow balls, or pebble-shaped large-particle adsorbents of different diameters, the adsorbents having the function of adsorbing carbon dioxide, hydrogen sulfide, and carbonyl sulfide. Blast furnace gas is input from the bottom of the side wall of each stage of the decarbonization and desulfurization adsorption device and output from the top of the side wall of each stage of the decarbonization and desulfurization adsorption device; The three layers of adsorbent in each stage of the decarbonization and desulfurization adsorption device are as follows: the adsorbent filled in the upper layer has a diameter of 40-50 mm, the adsorbent filled in the middle layer has a diameter of 30-40 mm, and the adsorbent filled in the lower layer has a diameter of 20-30 mm; The adsorbent in step S2 is a composite porous adsorbent made of one or more composites of carbon nitride, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, zirconium oxide, and cerium oxide as raw materials, which is molded and then sintered at 700-900°C; S3. The blast furnace gas after decarbonization and desulfurization is subjected to a pressure swing adsorption CO purification device (5) to separate CO and nitrogen and purify high-concentration CO gas.

2. The process according to claim 1, characterized in that: In step S1, the pretreatment device (1) dehydrates, dechlorinates and removes dust from the blast furnace gas by using a low-temperature chilled water cooling method to remove water, chloride ions and dust. A water outlet (11) is provided at the bottom of the pretreatment device (1). The temperature of the blast furnace gas after the cooling treatment is lower than 15°C.

3. The process according to claim 2, characterized in that: The low temperature is 0-5°C.

4. The process according to claim 1, characterized in that: A chilled water inlet (12) is provided below the side wall of the pretreatment device (1) in step S1, and a warm water outlet (13) is provided above the side wall. Cold energy is provided for heat exchange of blast furnace gas through the chilled water inlet (12), and warm water after heat exchange is discharged from the warm water outlet (13).

5. The process according to claim 1, characterized in that: The spray liquid used in the three-stage decarbonization and desulfurization adsorption device (4) in step S2 is salt-free water. The liquid after the spray treatment of the three-stage decarbonization and desulfurization adsorption device (4) is mixed with liquid ammonia added from the outside and serves as the spray liquid required by the two-stage decarbonization and desulfurization adsorption device (3), which is a mixture of ammonia water with a concentration of 15%-17% and ammonium carbonate with a concentration of less than 0.1%; the liquid after the spray treatment of the two-stage decarbonization and desulfurization adsorption device (3) serves as the spray liquid required by the one-stage decarbonization and desulfurization adsorption device (2), which is a mixture of ammonia water with a concentration of 10%-15%, ammonium carbonate with a concentration of less than 5% and ammonium bicarbonate with a concentration of less than 1%; after the spray treatment of the one-stage decarbonization and desulfurization adsorption device (2), the liquid coming out from the bottom of the one-stage decarbonization and desulfurization adsorption device (2) is a mixture of ammonium bicarbonate with a concentration of 15-20% and ammonium carbonate with a concentration of less than 1%.

6. The process according to claim 5, characterized in that: The first-stage decarbonization and desulfurization adsorption device (2) is provided with a first spray liquid inlet (21) for introducing spray liquid at the top, and a first drain port (22) for discharging spray liquid at the bottom; the second-stage decarbonization and desulfurization adsorption device (3) is provided with a second spray liquid inlet (31) for introducing spray liquid at the top, and a second drain port (32) for discharging spray liquid at the bottom; the third-stage decarbonization and desulfurization adsorption device (4) is provided with a third spray liquid inlet (41) for introducing spray liquid at the top, and a third drain port (42) for discharging spray liquid at the bottom.

7. The process according to claim 1, characterized in that: The content of sulfur species in the blast furnace gas after decarbonization and desulfurization treatment in step S3 is less than 5 ppm, and the content of carbon dioxide is less than 0.5%; the concentration of CO gas after pressure swing adsorption separation in the pressure swing adsorption CO purification device (5) is greater than 98.5%.

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