Process method for purifying CO from blast furnace gas through desulfurization and decarbonization

Abstract

The invention discloses a process method for purifying CO from blast furnace gas through desulfurization and decarbonization. The process method comprises the following steps: S1, introducing the blast furnace gas into a pretreatment device for cooling, dehydrating, dechlorinating and dedusting; s2, the coal gas is sequentially introduced into a first-stage decarburization and desulfurization adsorption device, a second-stage decarburization and desulfurization adsorption device and a third-stage decarburization and desulfurization adsorption device which are filled with large-particle adsorbents to be subjected to decarburization and desulfurization treatment, carbon dioxide, hydrogen sulfide and carbonyl sulfide in the coal gas are removed, the third-stage decarburization and desulfurization device sprays salt-free water, the second-stage decarburization and desulfurization device sprays ammonia water, and the first-stage decarburization and desulfurization device And S3, carrying out pressure swing adsorption on the blast furnace gas subjected to decarburization and desulfurization treatment to obtain high-concentration CO gas. According to the invention, the adsorption device is filled with the multi-stage and multi-layer large-particle adsorbent, and the adsorption and diversion effects of the large-particle adsorbent are utilized, so that the removal rate of sulfur species and carbon dioxide in the blast furnace gas by ammonia is improved, and meanwhile, ammonium bicarbonate is co-produced, so that the real desulfurization and decarbonization requirements are met. And high-concentration CO is obtained through pressure swing adsorption, so that high-added-value utilization of the blast furnace gas is realized.

Description

Technical Field

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

[0002] According to statistics, my country's steel industry is the industry with the highest carbon emissions in the manufacturing industry, accounting for about 15% of my country's total carbon emissions. Faced with the goals that the country has put forward for various industries to achieve, the steel industry is trying every means to save energy and reduce carbon emissions. Blast furnace gas in the steel industry is mainly used for fuel gas for regenerative hot blast furnaces, power generation, and mixing coke oven gas or converter gas as fuel gas for steel rolling and other processes, etc., which produces low added value and belongs to high carbon emission fuel. Therefore, how to make high added value comprehensive utilization of blast furnace gas and reduce the cost of steel production has always been an important issue that steel companies pay attention to. CN221051806U discloses that by coupling an activated carbon adsorption desulfurization and deacidification system with an organic amine absorption and capture carbon dioxide system, the fine desulfurization and carbon dioxide capture and emission reduction of blast furnace gas are achieved, and high calorific value blast furnace gas is obtained at the same time, achieving the purpose of low cost, high efficiency and low energy consumption to treat blast furnace gas. CN 115196590A discloses an economically reasonable, simple and feasible process for carbon capture and co-production of hydrogen 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, which can maximize the comprehensive resource utilization of multiple effective components in steel plant gas, etc. However, the above technologies all have high energy consumption technical means such as compressing blast furnace gas or using organic amines to absorb carbon dioxide, and how to remove carbon from gas with low energy consumption and produce CO gas at the same time is still a difficult problem that needs to be solved. Summary of the invention

[0003] In view of 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 a multi-stage, multi-layered large-particle adsorbent in an adsorption tower, the adsorption and diversion effects of the large-particle adsorbent are utilized to increase the residence time of the acid gas in the blast furnace gas in the adsorption tower, thereby effectively promoting the reaction of ammonia with the acid gas, and increasing the removal rate of ammonia for sulfur species and carbon dioxide in the blast furnace gas, while co-producing ammonium bicarbonate to achieve true desulfurization and decarbonization requirements; then, pressure swing adsorption is used to increase the concentration of CO, and the high-concentration CO is used as a raw material for other chemical synthesis, thereby realizing high added value utilization of blast furnace gas.

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

[0005] A process for desulfurizing and decarbonizing blast furnace gas to purify CO, comprising the following steps:

[0006] S1, passing blast furnace gas into a pretreatment device for low-temperature dehydration, dust removal and dechlorination;

[0007] S2. The pretreated blast furnace gas is sequentially introduced into 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 in the blast furnace gas, wherein 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 to purify high-concentration CO gas.

[0009] The pretreatment device in step S1 dehydrates, dechlorinates and removes dust from blast furnace gas by using a low-temperature chilled water cooling method to remove water, chloride ions and dust at the same time. 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 the 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 with different diameters. The adsorbents have 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 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 by 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 by 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 lower than 0.1%; the liquid after spraying treatment by the two-stage decarbonization and desulfurization adsorption device is used as the spray liquid required by 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 lower than 5% and ammonium bicarbonate with a concentration lower 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 lower than 1%.

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

[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. The present invention effectively increases the residence time of acidic gases in blast furnace gas in the decarbonization and desulfurization adsorption device by using multi-stage and multi-layer large particle adsorbents, thereby significantly improving the reaction efficiency of ammonia with sulfur species and carbon dioxide, and achieving efficient desulfurization and decarbonization. This innovative measure not only meets environmental protection requirements, but also creates favorable conditions for the subsequent CO purification step.

[0020] B. Compared with the prior art, the process of the present invention avoids high energy consumption compression or the use of organic amine adsorption and other means. Through ingenious design, the entire desulfurization and decarbonization process is carried out at low temperature and normal pressure, which greatly reduces energy consumption and meets 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 improving 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 drawings required for use in the specific embodiments will be briefly introduced below. 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 creative work.

[0024] Figure 1 It is a schematic diagram of the overall structure of the process system for desulfurization, decarbonization and purification of CO from blast furnace gas according to 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 drain port; 3-second-stage decarbonization and desulfurization adsorption device, 31-second spray liquid inlet, 32-second drain port; 4-third-stage decarbonization and desulfurization adsorption device, 41-third spray liquid inlet, 42-third drain 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 described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are 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 levels of desulfurization and decarbonization adsorption devices, and the three layers of adsorbents in each level of the device are: the upper layer is filled with a hollow spherical alumina adsorbent with a diameter of 40-50mm, the middle layer is filled with a pebble-shaped magnesium oxide adsorbent with a diameter of 30-40mm, and the lower layer is filled with a composite adsorbent composed of spherical alumina and magnesium oxide with a diameter of 20-30mm, and the above adsorbents are all roasted at 700°C in air for 12 hours. The three-stage decarbonization and desulfurization adsorption device 4 is sprayed with salt-free water, and the treated spray liquid is mixed with liquid ammonia as the spray liquid required for the secondary desulfurization and decarbonization, and its content is 15% ammonia water and 0.03% ammonium carbonate mixed liquid. The spray liquid treated by the secondary decarbonization and desulfurization adsorption device 3 is a mixed liquid of 11% ammonia water, 3% ammonium carbonate and 0.3% ammonium bicarbonate. The solution coming out of the bottom of the primary decarbonization and desulfurization adsorption device 2 is a mixed liquid of 20% ammonium bicarbonate and 0.5% ammonium carbonate. The blast furnace gas after three-stage desulfurization and decarbonization treatment contains 5% water, 0.3% carbon dioxide, 31% carbon monoxide and 63% nitrogen. The concentration of COS is 3ppm, 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 and decarbonizing blast furnace gas to purify CO, 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 levels of desulfurization and decarbonization adsorption devices, and the three layers of adsorbents in each level of the device are: the upper layer is filled with a hollow spherical zirconium oxide adsorbent with a diameter of 40-50mm, the middle layer is filled with a pebble-shaped silicon oxide adsorbent with a diameter of 30-40mm, and the lower layer is filled with a composite adsorbent composed of spherical zirconium oxide and silicon oxide with a diameter of 20-30mm, and the above adsorbents are all roasted at 800°C in air for 10 hours. The three-stage decarbonization and desulfurization adsorption device 4 is sprayed with salt-free water, and the treated spray liquid is mixed with liquid ammonia as the spray liquid required for the secondary desulfurization and decarbonization, and its content is 16% ammonia water and 0.02% ammonium carbonate mixed liquid. The spray liquid treated by the secondary decarbonization and desulfurization adsorption device 3 is a mixed liquid of 10% ammonia water, 5% ammonium carbonate and 0.1% ammonium bicarbonate. The solution coming out of the bottom of the primary decarbonization and desulfurization adsorption device 2 is a mixed liquid of 15% ammonium bicarbonate and 0.3% ammonium carbonate. The blast furnace gas after three-stage desulfurization and decarbonization treatment contains 6% water, 0.4% carbon dioxide, 32% carbon monoxide and 61% nitrogen. The concentration of COS is 2ppm, 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 and decarbonizing blast furnace gas to purify CO, 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 levels of desulfurization and decarbonization adsorption devices, and the three layers of adsorbent in each level of the device are: the upper layer is filled with a composite adsorbent of hollow spherical cerium oxide and zirconium oxide with a diameter of 40-50mm, the middle layer is filled with a composite adsorbent of pebble-shaped titanium oxide and magnesium oxide with a diameter of 30-40mm, and the lower layer is filled with a composite adsorbent composed of spherical aluminum oxide and silicon oxide with a diameter of 20-30mm, and the above adsorbents are all roasted at 900°C in air for 5 hours. The three-stage decarbonization and desulfurization adsorption device 4 is sprayed with salt-free water, and the treated spray liquid is mixed with liquid ammonia as the spray liquid required for the secondary desulfurization and decarbonization, and its content is 17% ammonia water and 0.05% ammonium carbonate mixed liquid. The spray liquid treated by the secondary decarbonization and desulfurization adsorption device 3 is a mixed liquid of 15% ammonia water, 1% ammonium carbonate and 0.2% ammonium bicarbonate. The solution coming out of the bottom of the primary decarbonization and desulfurization adsorption device 2 is a mixture of 18% ammonium bicarbonate and 0.4% ammonium carbonate. The blast furnace gas treated by the three-stage desulfurization and decarbonization contains 5% water, 0.5% carbon dioxide, 30% carbon monoxide and 64% nitrogen, the concentration of COS is 1ppm, 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 increases the removal rate of sulfur species and carbon dioxide in blast furnace gas by ammonia by filling a multi-stage multi-layer large-particle adsorbent in a decarbonization and desulfurization adsorption device, and utilizes the adsorption and diversion effects of the large-particle adsorbent, while simultaneously co-producing ammonium bicarbonate to achieve true desulfurization and decarbonization requirements. In this process, desulfurization and decarbonization do not involve temperature and pressure increase means, greatly reducing energy consumption, and the process is simple. Pressure swing adsorption is used to increase the concentration of CO, and the high-concentration CO is used as a raw material for other chemical synthesis, thereby realizing high added value 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 the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A process for desulfurizing and decarbonizing blast furnace gas to purify CO, 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 introduced into a primary decarbonization and desulfurization adsorption device (2), a secondary decarbonization and desulfurization adsorption device (3) and a tertiary 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, wherein the tertiary decarbonization and desulfurization adsorption device (4) is sprayed with salt-free water, the secondary decarbonization and desulfurization adsorption device (3) is sprayed with a certain concentration of ammonia water, and the primary decarbonization and desulfurization adsorption device (2) is sprayed with a certain concentration of low-carbonized ammonia water; 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 to purify high-concentration CO gas.

2. The process according to claim 1, characterized in that: In the step S1, the pretreatment device (1) dehydrates, dechlorinates and removes dust from the blast furnace gas by using a low-temperature refrigerated water cooling method to remove water, chloride ions and dust at the same time. A water outlet (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 according to claim 2, characterized in that: The low temperature is 0-5°C.

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

5. The process according to claim 1, characterized in that: 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 with different diameters. The adsorbents have 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 device.

6. The process according to claim 5, characterized in that: The three layers of adsorbent in each stage of the decarbonization and desulfurization adsorption device are as follows: the diameter of the adsorbent filled in the upper layer is 40-50mm, the diameter of the adsorbent filled in the middle layer is 30-40mm, and the diameter of the adsorbent filled in the lower layer is 20-30mm.

7. The process according to claim 1, characterized in that: 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.

8. The process according to claim 1, characterized in that: The spray liquid used by the three-stage decarbonization and desulfurization adsorption device (4) in the step S2 is salt-free water. The liquid after the spray treatment by the three-stage decarbonization and desulfurization adsorption device (4) is mixed with liquid ammonia added externally and used 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 lower than 0.1%; the liquid after the spray treatment by the two-stage decarbonization and desulfurization adsorption device (3) is used 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 lower than 5% and ammonium bicarbonate with a concentration lower than 1%; after the spray treatment by 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 lower than 1%.

9. The process according to claim 8, 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 liquid discharge port (22) for discharging the 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 liquid discharge port (32) for discharging the 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 liquid discharge port (42) for discharging the spray liquid at the bottom.

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

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