Multi-process staged coke oven gas desulfurization and decyanation device and process
Through the multi-process hierarchical treatment of coke oven gas desulfurization and decyanometry device and process, the multi-layer filler layer and multi-stage cooler design, the problem of low desulfurization efficiency of existing coke oven gas is solved, efficient desulfurization and cooling is achieved, and subsequent process needs are met, and the cleanliness and product quality of coke oven gas is improved.
Patent Information
- Application Number
- CN202510789352.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-08-12
AI Technical Summary
The existing coke oven gas desulfurization and decyanometry process is low, and the regenerated solution completed by the desorption tower is low, which affects the desulfurization process. The desorption acid gas outlet of the desorption tower is insufficient, resulting in a high concentration of hydrogen sulfide in the coke oven gas, affecting subsequent processes and product quality.
The coke oven gas desulfurization and decyanometry device and process using multi-process hierarchical treatment, including absorption towers and desorption towers, is designed through four-layer filler layers and 30-layer floating valve tower plates, combined with a solution distributor and a multi-stage cooler, the countercurrent contact between the coke oven gas and the absorbent liquid and multi-stage cooling, the heat exchange of the staging washing and regenerated solution, and the desulfurization efficiency and cooling effect are improved.
Effectively remove impurities such as H2S and HCN in coke oven gas to ensure that clean gas is supplied to the rear steel rolling users. After processing, the H2S content in the gas is ≤20mg/m3, and the desorption and acid gas are cooled to 28-32℃, meeting the subsequent acid production process needs and improving the quality and production efficiency of coke oven gas.
Smart Images
Figure CN120464439A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a coke oven gas desulfurization and decyanation device and process for multi-process graded treatment, belonging to the technical field of coke oven gas desulfurization and decyanation. Background Art
[0002] Against the backdrop of the current national environmental protection emission standards being gradually improved, it is necessary to effectively reduce the hydrogen sulfide content of coke oven gas at the source so that the coke oven gas can meet the product quality and emission requirements of downstream steel rolling users (avoiding excessive sulfur dioxide emissions in exhaust gas) and reduce natural gas consumption.
[0003] The current coke oven gas desulfurization and decyanation process has the following shortcomings: 1. The desulfurization and decyanation efficiency of coke oven gas is low, resulting in a high concentration of hydrogen sulfide in the coke oven gas, affecting the quality of the coke oven gas and the product quality of subsequent coke oven gas users; 2. The cooling efficiency of the regenerated solution after desorption in the desorption tower is low, resulting in the regenerated solution not reaching the optimal process reaction temperature, affecting the absorption reaction efficiency during the desulfurization process: specifically, the monoethanolamine aqueous solution after desorption is not fully cooled and is transported to the absorption tower for the absorption reaction of hydrogen sulfide removal from the coke oven gas, which will reduce the desulfurization efficiency; 3. The cooling capacity of the desorbed acid gas at the outlet of the desorption tower is insufficient, resulting in a low mass fraction of H2S gas in the desorbed acid gas, affecting subsequent acid production. Summary of the Invention
[0004] The present invention aims to provide a multi-step and graded coke oven gas desulfurization and decyanation device and process, which can efficiently remove impurities such as H2S and HCN from the coke oven gas, and can also remove a large amount of organic sulfur such as COS from the coke oven gas, ensuring that clean coke oven gas fuel is supplied to the rear steel rolling users, and the H2S content in the treated gas is ≤20mg / m 3 The removed H2S-rich acid gas is sent to the subsequent process to produce concentrated sulfuric acid.
[0005] The present invention provides a Solfiban coke oven gas desulfurization and decyanation device with multi-step hierarchical treatment, comprising an absorption tower and a desorption tower; The absorption tower is provided with four packing layers, namely, a first packing layer, a second packing layer, a third packing layer, and a fourth packing layer are evenly arranged from top to bottom, and a set of solution distributors and distribution tower plates are installed on the top of each packing layer. A coke oven gas inlet is provided at the bottom of the absorption tower, a clean coke oven gas outlet is provided at the top, and an absorption liquid inlet is provided on the top of each packing layer. The gas flows from bottom to top and contacts with the absorption liquid in countercurrent in the packing layer to cause absorption reaction; The desorption tower is equipped with 30 layers of float valve trays, a saturated absorption liquid inlet is provided at the top, and a flash steam inlet connected to a reboiler is provided at the bottom. The saturated absorption liquid flows from top to bottom in the desorption tower, and the flash steam flows from bottom to top in the desorption tower. The saturated absorption liquid at the top refers to the rich liquid of the monoethanolamine solution after absorbing hydrogen sulfide in the absorption tower. The flash steam inlet at the bottom is connected to the reboiler at the bottom of the desorption tower. The regenerated part of the monoethanolamine solution is sent from the bottom tray of the desorption tower to the reboiler for heating to generate flash steam that enters the desorption tower. The bottom of the absorption tower is provided with a saturated absorption liquid outlet, which is connected to the top of the desorption tower; the bottom inlet of the desorption tower is connected to the desorption tower reboiler. The absorption tower is composed of the second, third and fourth packing layers forming a primary scrubbing structure. The absorption liquid inlets of the second, third and fourth packing layers are connected to the primary regeneration liquid outlet of the desorption tower (the upper part of the desorption tower). The first packing layer of the absorption tower forms a secondary fine scrubbing structure. The absorption liquid inlet of the first packing layer is connected to the secondary regeneration liquid outlet of the desorption tower (the lower part of the desorption tower). The acid gas outlet at the top of the desorption tower is connected to a three-stage cooler, and the three-stage coolers are connected in series.
[0006] Furthermore, the first-level regeneration liquid outlet of the desorption tower is connected to the first-level heat exchanger and the first-level cooler respectively, and enters the absorption tower after cooling; the second-level regeneration liquid outlet is connected to the second-level heat exchanger and the second-level cooler respectively, and enters the absorption tower after cooling.
[0007] Furthermore, the first-stage heat exchanger and the second-stage heat exchanger are respectively solution spiral plate heat exchangers; the first-stage cooler and the second-stage cooler are respectively solution spiral plate coolers; the solution spiral plate heat exchanger is used for heat exchange between the room temperature solution of the absorption tower and the high temperature solution of the desorption tower, and the solution spiral plate cooler is used for secondary cooling of the regenerated solution coming out of the desorption tower after heat exchange and cooling.
[0008] Furthermore, a group of solution distributors are installed above each layer of filler in the absorption tower and are respectively connected to the regeneration solution outlets in the desorption tower.
[0009] Furthermore, the three-stage cooler is specifically: air cooler, circulating water cooler, and low-temperature water cooler. The air cooler is the first stage of cooling and adopts air cooling. Fin-tube air cooler equipment can be selected. The pipe material is 316Ti. The air cooler is equipped with a variable frequency fan. The outlet temperature is controlled by adjusting the operating frequency of the cooling fan of each air cooling equipment; the circulating water cooler is the second stage of cooling, and the low-temperature water cooler is the third stage of cooling. The second and third stage cooling adopt water cooling. Two shell and tube condensing cooler equipment can be selected. The tube side and shell side are made of 316L material. Flow regulating valves are installed on the circulating water and low-temperature water pipelines to control the outlet temperature by adjusting the cooling water volume.
[0010] The present invention provides a multi-step and graded coke oven gas desulfurization and decyanation process, comprising the following steps: (1) The coke oven gas to be treated enters the absorption tower from the lower part of the absorption tower, and the coke oven gas flows from bottom to top, and contacts with the absorption liquid in the packing layer in countercurrent to produce an absorption reaction; the absorption liquid is a monoethanolamine aqueous solution with a mass concentration of 15%; (2) The saturated absorption liquid of monoethanolamine is discharged from the bottom of the absorption tower and flows to the top of the desorption tower. It flows from top to bottom in the desorption tower. The flash steam from the reboiler connected to the desorption tower flows from bottom to top in the desorption tower. The saturated absorption liquid and the flash steam are in countercurrent contact on the floating valve tray. The saturated absorption liquid is heated by steam to flash off acid gases such as H2S and CO2, completing the regeneration of the solution. The flash steam is generated by taking out the partially regenerated monoethanolamine solution from the bottom tray of the desorption tower and entering the reboiler. (3) The regenerated monoethanolamine solution is cooled and recycled; the solution regenerated in the upper part of the desorption tower is the first-level regeneration solution, which is connected to the solution distributor of the three packing layers in the lower part of the absorption tower by a pipeline for the first-level initial washing; the solution regenerated in the lower part of the desorption tower is the second-level regeneration solution, which is connected to the solution distributor of the first packing layer in the upper part of the absorption tower by a pipeline for the second-level fine washing; (4) The gas discharged from the desorption tower is sent to the tertiary cooler and gas-liquid separator for cooling and recovery.
[0011] Specifically, the absorption tower uses a 15% monoethanolamine aqueous solution as the absorption liquid for desulfurization. The alkaline monoethanolamine solution has a strong absorption capacity for acidic gases such as H2S and CO2. At temperatures between 25 and 40°C, the monoethanolamine solution reacts with the acidic gases to form salts. At temperatures above 105°C, the resulting amine sulfides and carbonates decompose, releasing the acidic gases from the saturated solution.
[0012] In order to improve the efficiency of H2S removal reaction, coke oven gas is washed in two stages in the absorption tower. Washing is the absorption process. A set of solution distributors is installed above each layer of packing in the absorption tower. The solution passes through the lower packing from top to bottom and absorbs the rising coke oven gas. The first packing layer at the top of the absorption tower corresponds to the secondary regeneration solution from the bottom of the desorption tower. The solution regeneration degree is good and the washing accuracy is high. The second, third and fourth packing layers at the bottom of the absorption tower correspond to the first regeneration solution from the upper half of the desorption tower. The flow rate is large and the washing intensity is good. The amount of solution entering each layer of packing can be controlled by the valve installed on the solution pipeline entering the absorption tower. Specifically, the first regeneration solution in the upper half of the desorption tower is connected to the solution distributor of the three packing layers in the lower part of the absorption tower by a pipeline, and the second regeneration solution is connected to the solution distributor of the first packing layer at the top of the absorption tower by a pipeline. It can be achieved that the first-level initial washing is first performed with a mixed solution of the first and second-level regeneration solutions, and then the second-level fine washing is performed with the second-level solution. The primary scrubbing is characterized by a large solution flow rate and a high liquid-to-gas ratio in the absorption reaction, which can remove most of the H2S in the coal gas. The secondary fine scrubbing occurs in the top packing layer of the absorption tower. The desulfurization reaction of the secondary fine scrubbing is characterized by a low H2S concentration in the coal gas and a high purity of the regenerated solution. It can further remove the remaining H2S after the primary scrubbing and improve the desulfurization efficiency.
[0013] The desorption tower is regenerated in two stages. The first stage of regeneration is carried out on the trays in the upper half of the desorption tower. The saturated solution and the upward blowing steam are in countercurrent contact on the trays in the upper half. Most of the acid gas absorbed in the saturated solution is flashed out, completing the first stage of regeneration. The monoethanolamine solution after the first stage of regeneration is collected on the dividing trays in the upper part of the desorption tower. About 2 / 3 of the solution is pumped to the first stage heat exchanger for heat exchange with the saturated solution from the bottom of the absorption tower. After cooling, it is used in the absorption tower for the first stage of primary washing of coke oven gas. The other 1 / 3 of the solution overflows to the trays in the lower half of the desorption tower for the second stage of regeneration. On the lower half of the tower plate, the solution after the first-stage regeneration contacts the upward steam from the reboiler outlet in countercurrent, and the remaining acid gas in the solution continues to be flashed out, completing the second-stage regeneration. The solution regeneration degree is more complete and can be used for the second-stage fine washing of the absorption tower. The second-stage regenerated solution is collected at the bottom of the desorption tower and transported by a pump to the second-stage heat exchanger for heat exchange with the saturated solution from the bottom of the absorption tower. Then, after cooling, it is used for the second-stage fine washing of the coke oven gas in the absorption tower.
[0014] The regeneration solution is cooled to 42°C by the saturated solution in the primary and secondary heat exchangers, and then flows back into the primary and secondary coolers, where it is further cooled to 30°C by low-temperature water. In order to achieve the regeneration solution temperature required by the process, the cooler uses low-temperature water as the cooling medium. The cooler is small in size and has a good cooling effect. The hot side medium of the primary and secondary coolers is the regeneration solution to be cooled, with a hot side inlet temperature of 40-44°C and a hot side outlet temperature of 28-32°C. The cold side medium of the cooler uses 16-18°C low-temperature water, with a cold side inlet temperature of 16-18°C and a cold side outlet temperature of 21-24°C. A flow regulating valve is installed on the low-temperature water supply pipe of the cooler to adjust the low-temperature water flow according to the outlet regeneration solution temperature to ensure that the outlet temperature of the hot side regeneration solution does not exceed 32°C.
[0015] The desorbed acid gas at the desorption tower outlet is cooled in three stages, depending on the cooling method and cooling medium. The temperature is reduced from 109-112°C to 28-32°C. The acid gas then enters a gas-liquid separator to further remove moisture. The resulting acid gas is then piped to the downstream acid production process to produce concentrated sulfuric acid. Condensate from each cooling stage flows by gravity to a reflux collection tank, from which it is returned by a transfer pump to the top of the desorption tower for desorption. The first stage uses air cooling, aiming to cool the 109-112°C acid gas to 83-86°C. Finned-tube air coolers are used, using 316Ti tubing. Each air cooler is equipped with a variable-frequency fan. The outlet temperature is controlled by adjusting the fan frequency of each air-cooling unit. The second and third stages of cooling utilize water cooling, aiming to cool the 83-86°C acid gas to 28-32°C. Two shell-and-tube condenser coolers are used, with 316L material used for both the tube and shell sides. The second stage uses circulating water at 30-33°C, while the third stage uses low-temperature water at 16-18°C. Flow control valves are installed on the circulating and low-temperature water pipelines to control the outlet temperature by adjusting the cooling water flow. After the three stages of cooling, the acid gas temperature is 28-32°C, removing over 99.5% of its water content and reducing the H2S mass fraction in the acid gas to over 13.9%, meeting the requirements for concentrated sulfuric acid production in the subsequent acid production process.
[0016] Beneficial effects of the present invention: The multi-step graded coke oven gas desulfurization and decyanation device and process provided by the present invention can efficiently remove impurities such as H2S and HCN from the coke oven gas, and can also remove a large amount of organic sulfur such as COS from the coke oven gas, ensuring that clean coke oven gas fuel is supplied to the rear steel rolling users. The H2S content in the treated gas is ≤20mg / m 3 The removed H2S-rich acid gas is sent to the subsequent process to produce concentrated sulfuric acid. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a diagram of the coke oven gas desulfurization and decyanation device of the present invention; Figure 2 It is a structural schematic diagram of the absorption tower of the present invention; Figure 3 It is a structural schematic diagram of the desorption tower of the present invention.
[0018] In the figure: 1 is the absorption tower, 2 is the desorption tower, 3 is the reboiler, 4 is the air cooler, 5 is the circulating water cooler, 6 is the low-temperature water cooler, 7 is the gas-liquid separator, 8 is the reflux liquid collection tank, 9 is the primary heat exchanger, 10 is the secondary heat exchanger, 11 is the primary cooler, and 12 is the secondary cooler; A is coke oven gas, B is clean coke oven gas, and C is acid gas. DETAILED DESCRIPTION
[0019] The present invention is further illustrated below by way of examples, but is not limited to the following examples. Example 1
[0020] like Figures 1-3 As shown, the present invention provides a Solfiban coke oven gas desulfurization and decyanation device with multi-step hierarchical treatment, comprising an absorption tower 1 and a desorption tower 2; The absorption tower 1 is provided with four packing layers, namely, the first packing layer, the second packing layer, the third packing layer, and the fourth packing layer are evenly arranged from top to bottom, and a set of solution distributors and distribution tower plates are installed on the top of each packing layer. The absorption tower is provided with a coke oven gas A inlet at the bottom and an absorption liquid inlet at the top. The gas flows from bottom to top and contacts with the absorption liquid in countercurrent in the packing layer to cause absorption reaction. The desorption tower 2 is equipped with 30 layers of float valve trays, a saturated absorption liquid inlet is provided at the top, and a flash steam inlet connected to the reboiler is provided at the bottom. The saturated absorption liquid flows from top to bottom in the desorption tower, and the steam flows from bottom to top in the desorption tower. The saturated absorption liquid at the top refers to the rich liquid of the monoethanolamine solution after absorbing hydrogen sulfide in the absorption tower. The flash steam inlet at the bottom is connected to the desorption tower reboiler 3. The flash steam is the steam generated by the partially regenerated monoethanolamine solution taken out from the bottom tray of the desorption tower and heated in the reboiler (to provide heat for the desorption process). The bottom of the absorption tower is provided with a saturated absorption liquid outlet, which is connected to the top of the desorption tower; the bottom of the desorption tower is provided with a flash steam inlet which is connected to the desorption tower reboiler 3. The absorption tower is composed of the second, third and fourth packing layers forming a primary scrubbing structure. The absorption liquid inlets of the second, third and fourth packing layers are connected to the primary regeneration liquid outlet of the desorption tower (the upper part of the desorption tower). The first packing layer of the absorption tower forms a secondary fine scrubbing structure. The absorption liquid inlet of the first packing layer is connected to the secondary regeneration liquid outlet of the desorption tower (the lower part of the desorption tower). The acid gas outlet of the desorption tower is connected to the tertiary cooler, which is connected in series.
[0021] Furthermore, the first-level regeneration liquid outlet of the desorption tower 2 is connected to the first-level heat exchanger 9 and the first-level cooler 11 respectively, and enters the absorption tower after cooling; the second-level regeneration liquid outlet is connected to the second-level heat exchanger 10 and the second-level cooler 12 respectively, and enters the absorption tower after cooling.
[0022] Furthermore, the first-stage heat exchanger 9 and the second-stage heat exchanger 10 are respectively solution spiral plate heat exchangers; the first-stage cooler 11 and the second-stage cooler 12 are respectively solution spiral plate coolers; the solution spiral plate heat exchanger is used for heat exchange between the room temperature solution of the absorption tower and the high temperature solution of the desorption tower, and the solution spiral plate cooler is used for secondary cooling of the regenerated solution coming out of the desorption tower after heat exchange and cooling.
[0023] Furthermore, a group of solution distributors are installed above each layer of filler in the absorption tower and are respectively connected to the regeneration solution outlets in the desorption tower.
[0024] Furthermore, the three-stage cooler is specifically: air cooler 4, circulating water cooler 5, and low-temperature water cooler 6. The air cooler is the first stage of cooling and adopts air cooling. Fin-tube air cooler equipment can be selected. The pipe material is 316Ti. The air cooler is equipped with a variable frequency fan. The outlet temperature is controlled by adjusting the operating frequency of the cooling fan of each air cooling equipment; the circulating water cooler is the second stage of cooling, and the low-temperature water cooler is the third stage of cooling. The second and third stage cooling adopt water cooling. Two shell and tube condensing cooler equipment can be selected. The tube side and shell side are made of 316L material. Flow regulating valves are installed on the circulating water and low-temperature water pipelines. The outlet temperature is controlled by adjusting the cooling water volume.
[0025] The multi-step and graded coke oven gas desulfurization and decyanation process provided by the present invention comprises the following steps: (1) The coke oven gas A to be treated enters the absorption tower 1 from the lower part of the absorption tower. The coke oven gas A flows from bottom to top and contacts the absorption liquid in the packing layer in countercurrent to produce an absorption reaction. The treated clean coke oven gas B is discharged from the top of the absorption tower 1. The absorption liquid is a monoethanolamine aqueous solution with a mass concentration of 15%; (2) The saturated absorption liquid of monoethanolamine is discharged from the bottom of the absorption tower 1 and flows to the top of the desorption tower 2. It flows from top to bottom in the desorption tower 2. The flash steam from the reboiler connected to the desorption tower flows from bottom to top in the desorption tower. The saturated absorption liquid and the steam are in countercurrent contact on the floating valve tray. The saturated absorption liquid is heated by the steam to flash off acid gases such as H2S and CO2, completing the regeneration of the solution. The flash steam is the steam generated after the partially regenerated monoethanolamine solution is taken out from the bottom tray of the desorption tower and heated in the reboiler. (3) The regenerated monoethanolamine solution is cooled and recycled; the solution regenerated in the upper part of the desorption tower is the first-level regeneration solution, which is connected to the solution distributor of the three packing layers in the lower part of the absorption tower by a pipeline for the first-level initial washing; the solution regenerated in the lower part of the desorption tower is the second-level regeneration solution, which is connected to the solution distributor of the first packing layer in the upper part of the absorption tower by a pipeline for the second-level fine washing; (4) The gas discharged from the desorption tower is sent to the three-stage cooler, and then enters the air cooler 4, the circulating water cooler 5, and the low-temperature water cooler 6 for cooling. The acid gas C after separation in the gas-liquid separator 7 is sent to the acid production process.
[0026] Specifically, the absorption tower uses a 15% monoethanolamine aqueous solution as the absorption liquid for desulfurization. The alkaline monoethanolamine solution has a strong absorption capacity for acidic gases such as H2S and CO2. At temperatures between 25 and 40°C, the monoethanolamine solution reacts with the acidic gases to form salts. At temperatures above 105°C, the resulting amine sulfides and carbonates decompose, releasing the acidic gases from the saturated solution.
[0027] In order to improve the efficiency of H2S removal reaction, coke oven gas is washed in two stages in the absorption tower. Washing is the absorption process. A set of solution distributors is installed above each layer of packing in the absorption tower. The solution passes through the lower packing from top to bottom and absorbs the rising coke oven gas. The first packing layer at the top of the absorption tower corresponds to the secondary regeneration solution from the bottom of the desorption tower. The solution regeneration degree is good and the washing accuracy is high. The second, third and fourth packing layers at the bottom of the absorption tower correspond to the first regeneration solution from the upper half of the desorption tower. The flow rate is large and the washing intensity is good. The amount of solution entering each layer of packing can be controlled by the valve installed on the solution pipeline entering the absorption tower. Specifically, the first regeneration solution in the upper half of the desorption tower is connected to the solution distributor of the three packing layers in the lower part of the absorption tower by a pipeline, and the second regeneration solution is connected to the solution distributor of the first packing layer at the top of the absorption tower by a pipeline. It can be achieved that the first-level initial washing is first performed with a mixed solution of the first and second-level regeneration solutions, and then the second-level fine washing is performed with the second-level solution. The primary scrubbing is characterized by a large solution flow rate and a high liquid-to-gas ratio in the absorption reaction, which can remove most of the H2S in the coal gas. The secondary fine scrubbing occurs in the top packing layer of the absorption tower. The desulfurization reaction of the secondary fine scrubbing is characterized by a low H2S concentration in the coal gas and a high purity of the regenerated solution. It can further remove the remaining H2S after the primary scrubbing and improve the desulfurization efficiency.
[0028] The desorption tower is regenerated in two stages. The first stage of regeneration is carried out on the trays in the upper half of the desorption tower. The saturated solution and the upward blowing steam are in countercurrent contact on the trays in the upper half. Most of the acid gas absorbed in the saturated solution is flashed out, completing the first stage of regeneration. The monoethanolamine solution after the first stage of regeneration is collected on the upper dividing trays of the desorption tower. About 2 / 3 of the solution is pumped to the first-stage heat exchanger 9 for heat exchange with the saturated solution from the bottom of the absorption tower 1. Then, after cooling, it is used in the absorption tower for the first-stage primary washing of the coke oven gas. The other 1 / 3 of the solution overflows to the trays in the lower half of the desorption tower for the second stage of regeneration. On the lower half of the tray, the solution after the primary regeneration contacts the upward steam from the reboiler outlet in countercurrent, and the remaining acid gas in the solution continues to be flashed out, completing the secondary regeneration. The solution regeneration degree is more complete and can be used for the secondary fine washing of the absorption tower. The secondary regeneration solution is collected at the bottom of the desorption tower and transported by a pump to the secondary heat exchanger 10 for heat exchange with the saturated solution from the bottom of the absorption tower. Then, after cooling, it is used for the secondary fine washing of the coke oven gas in the absorption tower.
[0029] The primary regeneration liquid outlet of the desorption tower is connected to the primary heat exchanger 9 and the primary cooler 11, respectively, and enters the absorption tower 1 after cooling. The secondary regeneration liquid outlet is connected to the secondary heat exchanger 10 and the secondary cooler 12, respectively, and enters the absorption tower 1 after cooling. Specifically, the primary and secondary regeneration liquids enter the primary and secondary heat exchangers, respectively, where they are cooled to 42°C by the saturated solution. They then flow back into the primary and secondary solution spiral plate coolers, where they are further cooled to 30°C by low-temperature water. To achieve the regeneration solution temperature required by the process, the coolers use low-temperature water as the cooling medium. The coolers are small in size and have good cooling and cooling effects. The hot side medium of the spiral plate cooler is the regeneration solution to be cooled, with a hot side inlet temperature of 42°C and a hot side outlet temperature of 30°C. The cold side medium of the cooler uses 18°C low-temperature water, with a cold side inlet temperature of 18°C and a cold side outlet temperature of 23°C. A flow control valve is installed on the cooler's low-temperature water supply pipe to adjust the low-temperature water flow rate according to the outlet regeneration solution temperature to ensure that the outlet temperature of the hot side regeneration solution is 30°C.
[0030] The desorbed acid gas at the desorption tower outlet is cooled in three stages, depending on the cooling method and cooling medium. The acid gas is cooled from 110°C to 30°C. The acid gas then enters a gas-liquid separator 7, where water is removed. The resulting acid gas is then piped to the downstream acid production process, where concentrated sulfuric acid is produced. Condensate from each cooling stage flows by gravity to a reflux collection tank 8, where it is then pumped back to the top of the desorption tower for desorption. The first stage uses air cooling, aiming to cool the 110°C acid gas to 85°C. Fin-tube air coolers are used, using 316Ti tubing. Each air cooler is equipped with a variable-frequency fan. The outlet temperature is controlled by adjusting the fan frequency of each air-cooling unit. The second and third stages of cooling utilize water cooling, aiming to cool the 85°C acid gas to 30°C. Two shell-and-tube condenser coolers are used, with 316L material used for both the tube and shell sides. The second stage uses 32°C circulating water, while the third stage uses 18°C low-temperature water. Flow control valves are installed on the circulating and low-temperature water pipelines to control the outlet temperature by adjusting the cooling water flow. After the three-stage cooling process, the acid gas temperature is 30°C, and water content above 99.5% is removed, reducing the H2S mass fraction in the acid gas to above 13.9%, meeting the requirements for concentrated sulfuric acid production in the subsequent acid production process.
[0031] Before treatment, the H2S content in the coke oven gas produced by the 7.63m coke oven in the coking plant was about 6500-7500mg / m 3 After being treated by the process system of the present invention, H2S, HCN and other impurities in the coke oven gas can be removed efficiently, and at the same time, organic sulfur such as COS in the coke oven gas can be removed in large quantities, ensuring that clean coke oven gas fuel is supplied to the rear steel rolling users. The H2S content in the gas after treatment is ≤20mg / m 3 The removed H2S-rich acid gas is sent to the subsequent process to produce concentrated sulfuric acid.
[0032] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.
Claims
1. A multi-step and graded coke oven gas desulfurization and decyanation device, characterized in that Including absorption tower and desorption tower; The absorption tower is provided with four packing layers, namely, a first packing layer, a second packing layer, a third packing layer, and a fourth packing layer are evenly arranged from top to bottom, and a set of solution distributors and distribution tower plates are installed on the top of each packing layer. A coke oven gas inlet is provided at the bottom of the absorption tower, a clean coke oven gas outlet is provided at the top, and an absorption liquid inlet is provided on the top of each packing layer. The gas flows from bottom to top and contacts with the absorption liquid in countercurrent in the packing layer to cause absorption reaction; The desorption tower is equipped with 30 layers of float valve trays, a saturated absorption liquid inlet is provided at the top, and a flash steam inlet connected to the reboiler is provided at the bottom. The saturated absorption liquid flows from top to bottom in the desorption tower, and the flash steam flows from bottom to top in the desorption tower; a saturated absorption liquid outlet is provided at the bottom of the absorption tower, which is connected to the top of the desorption tower; The absorption tower is composed of the second, third and fourth packing layers to form a primary washing structure. The absorption liquid inlets of the second, third and fourth packing layers are connected to the first regeneration liquid outlet of the desorption tower. The first packing layer of the absorption tower forms a secondary fine washing structure, and the absorption liquid inlet of the first packing layer is connected to the secondary regeneration liquid outlet of the desorption tower; The acid gas outlet at the top of the desorption tower is connected to a three-stage cooler, and the three-stage coolers are connected in series.
2. The coke oven gas desulfurization and decyanation device with multi-step and graded treatment according to claim 1 is characterized in that: The first-level regeneration liquid outlet of the desorption tower is connected to the first-level heat exchanger and the first-level cooler respectively, and enters the absorption tower after cooling; the second-level regeneration liquid outlet is connected to the second-level heat exchanger and the second-level cooler respectively, and enters the absorption tower after cooling.
3. The coke oven gas desulfurization and decyanation device with multi-step hierarchical treatment according to claim 2, characterized in that: The first-stage heat exchanger and the second-stage heat exchanger are respectively solution spiral plate heat exchangers; the first-stage cooler and the second-stage cooler are respectively solution spiral plate coolers; the solution spiral plate heat exchanger is used for heat exchange between the room temperature solution of the absorption tower and the high temperature solution of the desorption tower, and the solution spiral plate cooler is used for secondary cooling of the regenerated solution coming out of the desorption tower after heat exchange and cooling.
4. The coke oven gas desulfurization and decyanation device with multi-step and graded treatment according to claim 1 is characterized in that: A set of solution distributors is installed above each layer of filler in the absorption tower and is respectively connected to the regeneration solution outlet in the desorption tower.
5. The coke oven gas desulfurization and decyanation device with multi-step and graded treatment according to claim 1 is characterized in that: The three-stage cooler is specifically composed of: air cooler, circulating water cooler, and low-temperature water cooler. The air cooler is the first stage of cooling, adopts air cooling, and uses finned tube air cooler equipment. The pipes are made of 316Ti material. The air cooler is equipped with a variable frequency fan. The outlet temperature is controlled by adjusting the operating frequency of the cooling fan of each air cooling equipment; the circulating water cooler is the second stage of cooling, and the low-temperature water cooler is the third stage of cooling. The second and third stage cooling adopt water cooling. Two shell and tube condensing coolers are selected. The tube side and shell side are made of 316L material. Flow regulating valves are installed on the circulating water and low-temperature water pipelines. The outlet temperature is controlled by adjusting the cooling water volume.
6. A multi-step graded coke oven gas desulfurization and decyanation process, using the multi-step graded coke oven gas desulfurization and decyanation device according to any one of claims 1 to 5, characterized in that The following steps are involved: (1) The coke oven gas to be treated enters the absorption tower from the bottom of the absorption tower. The coke oven gas flows from bottom to top and contacts the absorption liquid in the packing layer in countercurrent to produce absorption reaction. (2) The saturated absorption liquid is discharged from the bottom of the absorption tower and flows to the top of the desorption tower. It flows from top to bottom in the desorption tower. The flash steam from the reboiler connected to the desorption tower flows from bottom to top in the desorption tower. The saturated absorption liquid and the flash steam come into countercurrent contact on the floating valve tray. The saturated absorption liquid is heated by the steam to flash off the acid gas, completing the regeneration of the solution. (3) The regenerated monoethanolamine solution is cooled and recycled; the solution regenerated in the upper part of the desorption tower is the first-level regeneration solution, which is connected to the solution distributor of the three packing layers in the lower part of the absorption tower by a pipeline for the first-level initial washing; the solution regenerated in the lower part of the desorption tower is the second-level regeneration solution, which is connected to the solution distributor of the first packing layer in the upper part of the absorption tower by a pipeline for the second-level fine washing; (4) The gas discharged from the desorption tower is sent to the tertiary cooler and gas-liquid separator for cooling and recovery.
7. The multi-step and graded coke oven gas desulfurization and decyanation process according to claim 6, characterized in that: The absorption liquid in the absorption tower is a monoethanolamine aqueous solution with a mass concentration of 15%; the saturated absorption liquid at the top of the desorption tower refers to the rich monoethanolamine solution after absorbing hydrogen sulfide in the absorption tower, and the bottom flash steam is the partially regenerated monoethanolamine solution taken out from the bottom tray of the desorption tower and heated in the reboiler.
8. The multi-step and graded coke oven gas desulfurization and decyanation process according to claim 6, characterized in that: The coke oven gas is washed in two stages in the absorption tower. The absorption liquid passes through the lower packing from top to bottom and absorbs the rising coke oven gas. The first packing layer at the top of the absorption tower corresponds to the secondary regeneration solution from the bottom of the desorption tower, and the second, third and fourth packing layers at the bottom of the absorption tower correspond to the first regeneration solution from the upper half of the desorption tower. The amount of solution entering each layer of packing is controlled by the valve installed on the solution pipeline entering the absorption tower; the first regeneration solution in the upper half of the desorption tower is connected to the solution distributor of the three packing layers in the lower part of the absorption tower by a pipeline, and the second regeneration solution is connected to the solution distributor of the first packing layer at the top of the absorption tower by a pipeline, so as to realize the first-level preliminary washing with the mixed solution of the first and second regeneration solutions, and then the second-level fine washing with the second solution.
9. The multi-step and graded coke oven gas desulfurization and decyanation process according to claim 6, characterized in that: The desorption tower is regenerated in two stages. The first stage of regeneration is performed on the trays in the upper half of the desorption tower. On the trays, the saturated solution and the upward steam come into countercurrent contact. Most of the acid gases absorbed in the saturated solution are flashed off, completing the first stage of regeneration. The monoethanolamine solution after the first stage of regeneration is collected on the upper trays of the desorption tower. Two-thirds of the solution is pumped to the first stage heat exchanger for heat exchange with the saturated solution from the bottom of the absorption tower. After cooling, it is used in the absorption tower for primary scrubbing of the coke oven gas. The remaining one-third of the solution overflows to the trays in the lower half of the desorption tower for the second stage of regeneration. On the trays in the lower half of the desorption tower, the solution after the first stage of regeneration comes into countercurrent contact with the upward steam from the reboiler outlet. The remaining acid gases in the solution are further flashed off, completing the second stage of regeneration. The second stage of regeneration solution is collected in the lower part of the desorption tower and pumped to the second stage heat exchanger for heat exchange with the saturated solution from the bottom of the absorption tower. After cooling, it is used in the absorption tower for secondary fine scrubbing of the coke oven gas. The regeneration solution is cooled to 42°C by the saturated solution in the primary and secondary heat exchangers, and then enters the primary and secondary coolers backward, where it is further cooled to 30°C by low-temperature water. The primary and secondary coolers use low-temperature water as the cooling medium. The hot side medium of the primary and secondary coolers is the regeneration solution to be cooled, with a hot side inlet temperature of 40-44°C and a hot side outlet temperature of 28-32°C. The cold side medium of the cooler uses 16-18°C low-temperature water, with a cold side inlet temperature of 16-18°C and a cold side outlet temperature of 21-24°C.
10. The multi-step and graded coke oven gas desulfurization and decyanation process according to claim 6, characterized in that: The desorbed acid gas at the outlet of the desorption tower is cooled in three stages based on the cooling method and cooling medium, reducing the temperature of the acid gas from 109-112°C to 28-32°C. Specifically, the first stage uses air cooling to cool the 109-112°C acid gas to 83-86°C. The second and third stages use water cooling to cool the 83-86°C acid gas to 28-32°C. The second stage uses 30-33°C circulating water as the cooling medium, and the third stage uses 16-18°C low-temperature water as the cooling medium. After the three stages of cooling, the acid gas temperature is 28-32°C, and more than 99.5% of the water is discharged. The mass fraction of H2S gas in the acid gas reaches more than 13.9%, meeting the production requirements of concentrated sulfuric acid in the subsequent acid production process. The cooled acid gas enters the gas-liquid separator to further remove the water in the acid gas. The product acid gas is then transported through a pipeline to the subsequent acid production process to produce concentrated sulfuric acid. The condensed liquid after each stage of cooling flows to the reflux liquid collection tank by gravity, and then is returned to the top of the desorption tower by the delivery pump for desorption.