System for synergistically removing sulfide and carbon dioxide in blast furnace gas

Abstract

The utility model relates to a system for synergistically removing sulfides and carbon dioxide in blast furnace gas, which comprises a spray tower, a hydrolysis tower, an absorption tower and a water scrubber which are connected in sequence, and a first spray device for spraying alkali liquor to remove chloride ions in the gas is arranged in the spray tower; a hydrolysis catalyst for catalyzing organic sulfur in the coal gas to be hydrolyzed into H2S is arranged in the hydrolysis tower; a second spraying device for spraying an absorbent to absorb H2S and CO2 in the coal gas is arranged in the absorption tower; a third spraying device for spraying water is arranged in the water washing tower; the regeneration and separation device is used for regenerating, separating and recycling the absorbent, H2S and CO2, and is connected with the absorption tower. According to the utility model, organic sulfur is completely converted into H2S by utilizing the hydrolysis tower, CO2 and H2S are simultaneously absorbed by utilizing the absorption tower, and an absorbent barren solution, CO2 gas and elemental sulfur can be separated and recovered, so that the working procedures are effectively saved.

Description

Technical Field

[0001] The utility model belongs to the field of metallurgical environmental protection, and specifically relates to a system for collaboratively removing sulfide and carbon dioxide from blast furnace gas. Background Art

[0002] As a major carbon emitter, the steel industry is an important area for achieving green and low-carbon development. Achieving low-carbon development in the steel industry is of great significance. Carbon emissions from blast furnace ironmaking process in the steelmaking process account for ~45% of the long process steelmaking process, and it is a key link in carbon capture in the future steel industry. Through technical means to capture and utilize carbon dioxide from blast furnace gas, the quality and efficiency of blast furnace gas can be improved, greatly broadening the scope of blast furnace gas utilization.

[0003] Under the background of "ultra-low emission" in the steel industry, the blast furnace gas desulfurization, as the largest by-product of steel enterprises, is a responsibility. The implementation of fine desulfurization of blast furnace gas can significantly reduce the overall SO2 emissions of the steel industry. Therefore, it is an important way to implement ultra-low emission in the steel industry to control blast furnace gas from the source and realize blast furnace gas desulfurization. The main components of blast furnace gas are carbon dioxide, carbon monoxide, hydrogen, nitrogen, sulfide, etc. The application of desulfurization and decarbonization technology can effectively improve the quality and calorific value of blast furnace gas. The captured CO2 can be used for mineralization. At the same time, by capturing CO2 and sulfide, the concentration of CO in the gas is increased. The enriched CO can be reused in the ironmaking process to achieve green resource utilization. At present, the technology of desulfurization and decarbonization in natural gas is more studied, which is mainly aimed at low sulfur content, while there is very little research on blast furnace gas under high sulfur content and high carbon sulfur ratio conditions. At present, there is no mature application technology of blast furnace gas desulfurization and decarbonization at home and abroad. Summary of the invention

[0004] The purpose of the utility model is to overcome the above technical deficiencies, provide a system for collaboratively removing sulfide and carbon dioxide from blast furnace gas, and solve the technical problems of blast furnace gas desulfurization and decarbonization in the prior art.

[0005] In order to achieve the above technical purpose, the technical solution provided by the utility model is:

[0006] In the first aspect, the utility model provides a system for synergistically removing sulfide and carbon dioxide from blast furnace gas, comprising a spray tower, a hydrolysis tower, an absorption tower and a water washing tower connected in sequence, wherein the spray tower is provided with a first spray device for spraying alkaline solution to remove chloride ions in the coal gas; the hydrolysis tower is installed with a hydrolysis catalyst for catalyzing the hydrolysis of organic sulfur in the coal gas into H2S; the absorption tower is provided with a second spray device for spraying an absorbent to absorb H2S and CO2 in the coal gas; the water washing tower is provided with a third spray device for spraying water; and also includes a regeneration and separation device for regenerating and separating and recovering the absorbent, H2S and CO2, and the regeneration and separation device is connected to the absorption tower.

[0007] Preferably, the spray tower, hydrolysis tower, absorption tower and water washing tower are all provided with gas inlets and gas outlets, and are all bottom-in and top-out structures; a gas inlet for taking gas to detect H2S and CO2 concentrations is provided in the middle and upper part of the absorption tower.

[0008] Preferably, the regeneration and separation device comprises a flash tank, a gas-liquid separation tank, a first regeneration tower and a desulfurization tower, wherein an absorbent outlet is provided at the bottom of the absorption tower and is connected to the flash tank through a pump;

[0009] The top of the flash tank is connected to the inlet of the gas-liquid separation tank by setting a gas outlet, and the gas-liquid separation tank is connected to the desulfurization tower by setting a gas outlet. The desulfurization tower is arranged with a desulfurizer for absorbing H2S, and a CO2 discharge outlet is set at the top of the desulfurization tower;

[0010] The bottoms of the flash tank and the gas-liquid separation tank are connected to the first regeneration tower through the provision of liquid outlets.

[0011] Further preferably, there are two flash tanks, and the two flash tanks are arranged in parallel.

[0012] Further preferably, the absorption tower is connected to the rich liquid inlet of the first lean and rich liquid heat exchanger through a rich liquid pump, and the rich liquid outlet of the first lean and rich liquid heat exchanger is connected to the side wall inlet of the flash tank; the liquid outlet at the bottom of the flash tank is connected to the rich liquid inlet of the second lean and rich liquid heat exchanger, and the rich liquid outlet of the second lean and rich liquid heat exchanger is connected to the upper spray inlet of the first regeneration tower through a rich liquid heater; a gas outlet is arranged at the top of the first regeneration tower and is connected to the inlet of the gas-liquid separation tank through the first cooler, and the gas outlet at the top of the flash tank is also connected to the inlet of the gas-liquid separation tank through the first cooler; a liquid outlet is arranged at the bottom of the first regeneration tower and is connected to the lean liquid inlet of the second lean and rich liquid heat exchanger through a lean liquid pump, the lean liquid outlet of the second lean and rich liquid heat exchanger is connected to the lean liquid inlet of the first lean and rich liquid heat exchanger, and the lean liquid outlet of the first lean and rich liquid heat exchanger is connected to the upper inlet of the absorption tower through the second cooler, so as to return the absorbent lean liquid to the absorption tower for reuse.

[0013] Further preferably, a liquid outlet is provided at the bottom of the first regeneration tower and is connected to a reboiler, and the reboiler is connected to an inlet of a lower side wall of the first regeneration tower, so as to form a loop for heating part of the absorbent.

[0014] Further preferably, it also includes a water storage tank for storing blast furnace slag flushing water, the flash tank is wrapped with a jacket, and the water storage tank is connected to the jacket to form a heating circuit.

[0015] More preferably, the reboiler is connected to a heat source device, which includes a first heat exchanger for exchanging heat with a water storage tank and a second heat exchanger for exchanging heat with a high-temperature steam heat source.

[0016] More preferably, the method further comprises a second regeneration tower for regenerating and recycling the adsorption saturated desulfurizer.

[0017] Compared with the prior art, the beneficial effects of the utility model include:

[0018] The utility model provides a spray tower to ensure that chloride ions in the flue gas are removed and at the same time form saturated wet flue gas, thereby reducing the subsequent poisoning of the hydrolysis catalyst; the hydrolysis tower is further provided to ensure that the organic sulfur in the coal gas is completely hydrolyzed into H2S, which is beneficial to the subsequent absorption of sulfides, and the absorbent is sprayed on the absorption tower to remove H2S and CO2 at the same time, and the absorbent lean liquid, CO2 gas and sulfur element can be separated and recovered, the absorbent lean liquid is returned to the absorption tower for reuse, and the CO2 gas can be used for mineralization, production of chemicals, smelting and spraying back into blast furnaces, etc. The utility model can realize the simultaneous treatment of sulfides and carbon dioxide in blast furnace gas during the smelting process of the steel industry, and effectively save processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to the utility model;

[0020] Among them, 1-spray tower, 2-hydrolysis tower, 3-absorption tower, 4-second cooler, 5-water washing tower, 6-first flash tank, 7-second flash tank, 8-first cooler, 9-gas-liquid separation tank, 10-first heat exchanger, 11-water storage tank, 12-desulfurization tower, 13-second regeneration tower, 14-second heat exchanger, 15-reboiler, 16-first regeneration tower, 17-rich liquid heater, 18-lean liquid pump, 19-second lean and rich liquid heat exchanger, 20-first lean and rich liquid heat exchanger, 21-rich liquid pump;

[0021] Figure 2 The utility model is a process flow chart for collaboratively removing sulfide and carbon dioxide from blast furnace gas. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0023] In the description of the present utility model, the technical terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary and secondary relationship of the indicated technical features.

[0024] The main components of blast furnace gas are carbon dioxide, carbon monoxide, hydrogen, nitrogen, sulfide, etc. In order to effectively reduce SO2 emissions and carbon emissions, it is necessary to desulfurize and decarbonize blast furnace gas.

[0025] First, see Figure 1 The utility model proposes a system for collaboratively removing sulfide and carbon dioxide from blast furnace gas, comprising a spray tower 1, a hydrolysis tower 2, an absorption tower 3 and a water washing tower 5 which are connected in sequence.

[0026] A gas inlet A is arranged on the lower side wall of the spray tower 1, and a first spray device for spraying alkaline solution to remove chloride ions in the coal gas is arranged in the spray tower 1; a hydrolysis catalyst for catalyzing the hydrolysis of organic sulfur in the coal gas into H2S is installed in the hydrolysis tower 2; a second spray device for spraying an absorbent to absorb H2S and CO2 in the coal gas is arranged in the absorption tower 3; a third spray device for spraying water is arranged in the water washing tower 5; and a gas outlet B is opened at the top of the water washing tower 5.

[0027] In some embodiments, the first spray device provided in the spray tower 1, the second spray device provided in the absorption tower 3, and the third spray device provided in the water washing tower 5 may include a spray head, a nozzle or a spray pipe, etc., which may be selected according to the specific situation as long as the spraying function can be realized, and no specific limitation is made here.

[0028] In some embodiments, the spray tower 1, the hydrolysis tower 2, the absorption tower 3 and the water washing tower 5 are all bottom-in and top-out structures; for example, the first gas inlet A is arranged at the bottom of the spray tower 1, and the first gas outlet is arranged at the top; the second gas inlet is arranged at the bottom of the hydrolysis tower 2, and the second gas outlet is arranged at the top; the third gas inlet is arranged at the bottom of the absorption tower 3, and the third gas outlet is arranged at the top; the fourth gas inlet is arranged at the bottom of the water washing tower 5, and the fourth gas outlet B is arranged at the top; the first gas outlet is connected to the second gas inlet, the second gas outlet is connected to the third gas inlet, and the third gas outlet is connected to the fourth gas inlet.

[0029] The utility model system is provided with a spray tower 1 before the absorption tower 3, which can form saturated wet flue gas while ensuring the removal of chloride ions in the flue gas. A hydrolysis tower 2 is provided before the absorption tower 3, which can ensure that the organic sulfur in the coal gas is completely hydrolyzed into H2S, which is beneficial to the subsequent absorption of sulfides.

[0030] In some embodiments, a gas outlet is provided in the middle and upper part of the absorption tower 3, and the concentrations of H2S and CO2 are detected by periodic gas extraction, and whether H2S and CO2 penetrate is analyzed to determine whether the absorption liquid is saturated.

[0031] In some embodiments, the absorbent sprayed in the absorption tower 3 is an organic amine solution, and more preferably an MDEA series organic alcohol amine solution absorbent.

[0032] During the working process, the blast furnace gas produced by the blast furnace is pre-treated by a combination of gravity dust removal and bag dust removal. The gas temperature is about 150°C. After the gas is powered by the residual pressure turbine (TRT), the gas temperature drops to 50°C and sulfide and CO2 are removed. The gas after sulfide and CO2 removal is returned to the blast furnace gas pipeline; specifically:

[0033] The pretreated coal gas enters the spray tower 1 from the first coal gas inlet A, and is eluted by the first spray device to remove the chloride ions in the coal gas. After spraying, the coal gas temperature drops to about 35°C; then it enters the hydrolysis tower 2 to react with the hydrolysis catalyst to completely hydrolyze the organic sulfur COS into H2S; then it enters the absorption tower 3 to remove H2S and CO2; and after being discharged from the top of the absorption tower 3, it enters the water washing tower 5 to remove the absorption liquid carried in the coal gas to obtain desulfurized and decarbonized coal gas, which is discharged from the fourth coal gas outlet B of the water washing tower 5 and returned to the pipeline network for utilization, such as returning to the steel plant's gas pipeline for waste heat recovery and gas power generation.

[0034] In some embodiments, the system of the present invention further includes a regeneration separation device for regenerating and separating and recovering the absorbent, H2S and CO2; the regeneration separation device is connected to the absorption tower 3.

[0035] Preferably, the regeneration and separation device includes a flash tank, a gas-liquid separation tank 9, a first regeneration tower 16, and a desulfurization tower 12, wherein an absorbent outlet is arranged at the bottom of the absorption tower 3 and is connected to the flash tank through a pump, so as to partially release H2S and CO2; the top of the flash tank is connected to the inlet of the gas-liquid separation tank 9 by arranging a gas outlet, and the gas-liquid separation tank 9 is connected to the desulfurization tower 12 by arranging a gas outlet, a desulfurizer is arranged in the desulfurization tower 12, so as to absorb H2S and discharge high-purity CO2 from the top of the desulfurization tower 12; the bottoms of the flash tank and the gas-liquid separation tank 9 are respectively connected to the first regeneration tower 16 by arranging a liquid outlet, so as to regenerate the organic amine solution discharged from the flash tank and the gas-liquid separation tank 9.

[0036] Further preferably, there are two flash tanks, and the two flash tanks are arranged in parallel. By arranging the first flash tank 6 and the second flash tank 7 in parallel, the rich liquid is preliminarily released with a portion of sulfide and CO2, thereby reducing the load of the subsequent regeneration tower for analyzing sulfide and CO2.

[0037] Further preferably, the absorption tower 3 is connected to the rich liquid inlet of the first lean-rich liquid heat exchanger 20 through a rich liquid pump 21, and the rich liquid outlet of the first lean-rich liquid heat exchanger 20 is connected to the side wall inlet of the flash tank; the liquid outlet at the bottom of the flash tank is connected to the rich liquid inlet of the second lean-rich liquid heat exchanger 19, and the rich liquid outlet of the second lean-rich liquid heat exchanger 19 is connected to the upper spray inlet of the first regeneration tower 16 through a rich liquid heater 17, and a gas outlet is arranged on the top of the first regeneration tower 16 and is connected to the inlet of the gas-liquid separation tank 9 through the first cooler 8. The gas outlet at the top of the flash tank is also connected to the inlet of the gas-liquid separation tank 9 through the first cooler 8; a liquid outlet is arranged at the bottom of the first regeneration tower 16 and is connected to the lean liquid inlet of the second lean-rich liquid heat exchanger 19 through the lean liquid pump 18, the lean liquid outlet of the second lean-rich liquid heat exchanger 19 is connected to the lean liquid inlet of the first lean-rich liquid heat exchanger 20, and the lean liquid outlet of the first lean-rich liquid heat exchanger 20 is connected to the upper inlet of the absorption tower 3 through the second cooler 4, so as to return the absorbent lean liquid to the absorption tower for repeated use.

[0038] The utility model completes partial H2S and CO2 removal through a flash tank, and then completes complete H2S and CO2 removal through a first regeneration tower 16, and the obtained lean liquid, i.e., the organic amine solution absorbent, is returned to the absorption tower for repeated use.

[0039] Further preferably, a liquid outlet is provided at the bottom of the first regeneration tower 16 and connected to the reboiler 15, and the reboiler 15 is connected to the inlet of the lower side wall of the first regeneration tower 16 to form a loop, so as to heat part of the organic amine solution and flow to the bottom of the first regeneration tower 16 to maintain it at a certain temperature. The heat source of the reboiler 15 is water vapor, specifically formed by circulating water heated by a high-temperature steam heat source.

[0040] Further preferably, the utility model also includes a water storage tank 11 for storing blast furnace slag flushing water, the flash tank is wrapped with a jacket, the water storage tank 11 is connected to the jacket to form a heating circuit; the circulating water in the heat source of the reboiler 15 first exchanges heat with the water storage tank 11 through the first heat exchanger 10, and then exchanges heat with the high-temperature steam heat source through the second heat exchanger 14 to form water vapor; the water storage tank 11 serves as a partial heat source for the flash tank and the reboiler 15, effectively improving the utilization rate of waste heat.

[0041] The utility model realizes full utilization of low-grade waste heat in the steel industry by arranging a lean-rich liquid heat exchanger and utilizing blast furnace slag flushing water as a partial heat source for a flash tank and a reboiler.

[0042] Preferably, the utility model further comprises a second regeneration tower 13 for regenerating and recycling the adsorption saturated desulfurizer to obtain elemental sulfur.

[0043] The utility model system is based on the properties of carbon dioxide and sulfide to desulfurize and decarbonize blast furnace gas. Its main mechanism of action is: considering that the amount of CO2 in the gas far exceeds H2S and COS (carbonyl sulfide), a hydrolysis tower 2 is set before the absorption tower 3, and the organic sulfur is completely converted into H2S by a hydrolysis catalyst, and then the absorbent is used to absorb CO2 and H2S at the same time, and the saturated organic amine solution is transferred to the regeneration tower, and the CO2 and H2S are regenerated and released by heating. Then, the regenerated gas passes through the desulfurizer in the desulfurization tower to selectively absorb H2S to obtain enriched CO2. The saturated desulfurizer is recycled after regeneration, and elemental sulfur is obtained for downstream production. The desulfurized and decarbonized coal gas obtained after the absorption is completed is returned to the pipeline network for coal gas power generation or back-spraying into the blast furnace.

[0044] Therefore, the system of the utility model first absorbs sulfide and CO2 in the coal gas simultaneously, and then absorbs sulfide in steps. This process can ensure that desulfurization and decarbonization are achieved in the same system.

[0045] See also Figure 2 , using the utility model system to collaboratively remove sulfide and carbon dioxide from blast furnace gas, specifically including the following steps:

[0046] Step 1: The coal gas to be treated enters the spray tower 1, in which alkaline solution is sprayed to remove chloride ions in the coal gas, thereby reducing the subsequent poisoning of the hydrolysis catalyst and making the coal gas into saturated wet gas to obtain wet coal gas; the wet coal gas coming out of the top of the spray tower 1 enters from the bottom of the hydrolysis tower 2 and flows toward the top of the tower; the wet coal gas reacts with the hydrolysis catalyst installed in the hydrolysis tower 2 during its upward movement in the hydrolysis tower 2, and completely hydrolyzes the organic sulfur COS into H2S to obtain hydrolyzed coal gas.

[0047] Step 2: The hydrolyzed coal gas then enters the absorption tower 3, and undergoes a countercurrent reaction with the organic amine solution sprayed from the absorption tower 3, and H2S and CO2 are removed at the same time, thereby obtaining a first desulfurized and decarbonized coal gas and an absorption liquid containing H2S and CO2; the first desulfurized and decarbonized coal gas is discharged from the top of the absorption tower 3 and enters the water washing tower 5, in which water is sprayed to remove organic amine droplets carried in the first desulfurized and decarbonized coal gas, thereby obtaining a second desulfurized and decarbonized coal gas; the second desulfurized and decarbonized coal gas is discharged from the coal gas outlet B at the top of the water washing tower 5, and returned to the coal gas network for utilization, while the dilute organic amine liquid is collected at the bottom of the water washing tower 5 and re-pumped back to the absorption tower 3 for circulating washing.

[0048] Step 3: The saturated organic amine solution at the bottom of the absorber is used as the first rich liquid for gas-liquid separation to obtain an absorbent lean liquid and a gas mixture of H2S and CO2; CO2 gas and sulfur are recovered from the gas mixture, and the absorbent lean liquid is returned to the absorber for reuse; specifically comprising:

[0049] Step 3.1: Take gas from the absorption tower 3 regularly to detect the concentration of H2S and CO2, and analyze and determine whether H2S and CO2 have penetrated to judge whether the absorption liquid is saturated with adsorption; when saturated with adsorption, the organic amine solution saturated with H2S and CO2 at the bottom of the absorption tower 3 is the first rich liquid, which passes through the rich liquid pump 21 and the first lean-rich liquid heat exchanger 20 in turn and is divided into two paths, entering the first flash tank 6 and the second flash tank 7 respectively. The saturated organic amine solution releases a part of H2S and CO2 after decompression in the two flash tanks to obtain the second rich liquid;

[0050] Step 3.2: The second rich liquid is then discharged from the bottom of the two flash tanks and heated in turn by the second lean-rich liquid heat exchanger 19 and the rich liquid heater 17, then enters the upper spray regeneration of the first regeneration tower 16 and flows to the bottom of the tower. Part of the organic amine solution at the bottom of the first regeneration tower 16 will be circulated and heated in the reboiler 15 to maintain the temperature of the first regeneration tower 16. The second rich liquid gradually releases the remaining H2S and CO2 in the process of flowing to the bottom of the tower, and after being analyzed by the continuously high-temperature reboiler 15 and the first regeneration tower 16, a lean liquid is formed (which can be tested regularly); the organic amine lean liquid with absorption capacity is discharged from the bottom of the first regeneration tower 16, and is transported by the lean liquid pump 18, and passes through the second lean-rich liquid heat exchanger 19 and the first lean-rich liquid heat exchanger 20 in turn, and heats and absorbs the saturated organic amine (first rich liquid), while its own temperature is reduced. Finally, it is cooled by the second cooler 4 and returns to the absorption tower 3 for repeated absorption; that is, the organic amine liquid is in a circulating state in the entire reaction system;

[0051] Step 3.3: The H2S and CO2 analyzed by the first regeneration tower 16 are combined with the regeneration gas released from the top of the two flash tanks through the top outlet of the first regeneration tower 16 to obtain a gas mixture of H2S and CO2. The water in the gas of the H2S and CO2 gas mixture will be condensed after passing through the first cooler 8, and the condensed water will absorb the organic amines carried in the gas; then, the steam-water mixture is separated by the gas-liquid separation tank 9, and the liquid (water containing organic amines) at the bottom of the gas-liquid separation tank 9 is refluxed from the bottom of the gas-liquid separation tank 9 and returned to the first regeneration tower 16 to supplement the water volume of the entire circulating absorption regeneration system, and the gas is discharged from the middle or top of the gas-liquid separation tank into the desulfurization tower 12;

[0052] Step 3.4: In the desulfurization tower 12, the analyzed mixed gas flows upward from the bottom of the desulfurization tower 12, enters the bed filled with desulfurizer, and selectively absorbs H2S, and high-purity CO2 is discharged from the top of the desulfurization tower 12. The desulfurizer adsorbed and saturated with H2S is transferred to the second regeneration tower 13, regenerated and recycled in an oxygen atmosphere, and sulfur is obtained.

[0053] The utility model can be applied to blast furnace gas carbon capture and synergistic desulfurization. The gas after gravity dust removal and electrostatic dust removal can be effectively removed from sulfide and carbon dioxide through the utility model system, and the calorific value and reduction capacity of the purified gas are significantly improved. In addition, the high-purity carbon dioxide obtained by capture can be used for mineralization, production of chemicals, smelting and spraying back into blast furnaces, etc.; the sulfide obtained by removal finally exists in the form of elemental sulfur, which can be used as downstream chemical raw materials after purification. The proposal of this process system can effectively purify blast furnace gas and help the steel industry reduce pollution and carbon.

[0054] Preferably, the hydrolysis tower 2 is a packed tower, fixedly filled with COS hydrolysis catalyst, and the filling rate is 50-70%, such as 50%, 55%, 60%, 65% or 70%, etc.; the hydrolysis catalyst is an Al2O3-based loaded K2CO3 supported catalyst; the temperature of the wet coal gas entering the hydrolysis tower 2 is 20-40°C, such as 20°C, 25°C, 28°C, 30°C, 32°C, 35°C, 36°C, 38°C or 40°C; the space velocity (gas amount treated by unit volume of catalyst per unit time) of the wet coal gas in the hydrolysis tower 2 is in the range of 500-1500h -1 If the air velocity is too low and the residence time is too long, it will not be conducive to improving the overall efficiency. If the air velocity is too high and the residence time is too short, it will lead to incomplete hydrolysis. The hydrolysis reaction mechanism involved is:

[0055] COS + H2O → H2S + CO2 (Ⅰ)

[0056] Preferably, the gas velocity of the hydrolyzed coal gas in the absorption tower 3 is 0.5-1.5 m / s, and the flow rate of the absorbent is 1.5-2.5 t / h; the absorbent sprayed in the absorption tower 3 is an organic amine solution, and more preferably an MDEA series organic alcohol amine solution absorbent, which has a good absorption effect and an absorption efficiency of >90%. The alcohol amine solution absorption mechanism involved is:

[0057]

[0058]

[0059] Preferably, the desulfurization tower 12 of the utility model is a packed tower, which is fixedly loaded with iron oxide desulfurizer, so as to ensure that the organic sulfur in the coal gas is completely absorbed by H2S to obtain high-purity CO2. The absorption and regeneration reaction mechanism of the desulfurizer involved in the utility model for hydrogen sulfide is:

[0060] Fe2O3·xH2O + 3H2S → Fe2S3·xH2O + 3H2O (IV)

[0061] Fe2S3·xH2O + O2 → Fe2O3·xH2O + 3S (Ⅴ)

[0062] Further preferably, the iron oxide desulfurizer can be regenerated and reused multiple times.

[0063] The present invention is further described in detail below through specific embodiments.

[0064] Example 1

[0065] Step 1: 200Nm 3 / h, 50℃, 0.2MPa blast furnace gas first passes through the spray tower 1, and the alkali solution sprayed in the tower removes the chloride ions in the gas and turns the flue gas into saturated wet gas. Then the blast furnace gas at room temperature and 0.2MPa is heated at a space velocity of 1000h -1 The COS in the coal gas is converted into H2S by the hydrolysis tower 2, which is filled with a COS hydrolysis catalyst accounting for 60% of the tower volume (for example, a 100L hydrolysis tower is filled with 60L of a catalyst with a diameter of 4mm) to obtain hydrolyzed coal gas.

[0066] Step 2: The hydrolyzed coal gas after hydrolysis enters the absorption tower 3 from the bottom and flows to the top of the tower at a gas velocity of about 1m / s. At the same time, an organic amine solution with a temperature of 40°C and a concentration of 40% is sprayed out from the top of the tower and flows to the bottom of the tower at a flow rate of 2t / h. The hydrolyzed coal gas and the organic amine solution undergo a countercurrent contact reaction in the absorption tower 3, and the H2S and CO2 in the hydrolyzed coal gas are absorbed by the organic amine solution. The first desulfurized and decarbonized coal gas is about 160Nm 3 / h, the temperature is 40℃, and it is discharged from the top of the absorption tower 3 into the water washing tower 5, where the organic amine droplets carried in the first desulfurized and decarbonized coal gas are removed under the elution of circulating water to obtain the clean second desulfurized and decarbonized coal gas, which is returned to the pipeline network for waste heat recovery and coal gas power generation. The elution water containing organic amine liquid at the bottom of the water washing tower 5 is returned to the absorption tower 3 again.

[0067] Step 3: performing gas-liquid separation on the saturated organic amine solution (as the first rich liquid) at the bottom of the absorption tower to obtain an organic amine lean liquid and a gas mixture of H2S and CO2; recovering CO2 gas and sulfur from the gas mixture, and returning the organic amine lean liquid to the absorption tower for reuse; specifically comprising:

[0068] Step 3.1: The temperature of the absorbed saturated organic amine solution is 35°C. It is discharged from the bottom of the absorption tower 3 and transported by the rich liquid pump 21. After being heated to 70°C in the first lean-rich liquid heat exchanger 20, it is evenly divided into two streams and enters the first flash tank 6 and the second flash tank 7 connected in parallel.

[0069] The top pressure of the first flash tank 6 and the second flash tank 7 is 0.01Mpa. The bottom of the tower is wrapped with a jacket with 75℃ blast furnace slag water as the heat source to provide heat for the flash tank. The organic amine solution (first rich liquid) enters from the middle of the flash tank, and decompression evaporation occurs inside the flash tank, releasing some H2S and CO2. The mixed gas flow rate is 20Nm 3 / h. The organic amine solution after releasing gas is discharged from the bottom of the flash tank with a temperature of about 65°C and merged into one channel to form the second rich liquid.

[0070] Step 3.2: The second rich liquid has a flow rate of 2 t / h. It is heated to 75°C by the second lean-rich liquid heat exchanger 19, and then continues to be heated to 95°C by the rich liquid heater 17. It enters the first regeneration tower 16 from the top of the tower and flows to the bottom of the tower. Part of the organic amine solution at the bottom of the first regeneration tower 16 will be circulated and heated in the reboiler 15 at a temperature of 115°C to maintain the bottom temperature of the first regeneration tower 16 at 100°C. The organic amine solution (second rich liquid) gradually releases the remaining H2S and CO2, about 25Nm 3 / h of gas is discharged from the top of the first regeneration tower 16. After the organic amine lean liquid (2t / h, 100°C) with absorption capacity is discharged from the bottom of the first regeneration tower 16, it is transported by the lean liquid pump 18 and cooled to 80°C by the second lean-rich liquid heat exchanger 19, and then cooled to 63°C by the first lean-rich liquid heat exchanger 20. The exchanged heat is used to heat the first rich liquid and the second rich liquid. Finally, it is cooled to about 40°C by the second cooler 4 and enters the absorption tower 3 for reuse.

[0071] Step 3.3: The H2S and CO2 released from the two flash tanks and the first regeneration tower 16 are combined to obtain a H2S and CO2 gas mixture with a flow rate of about 45Nm 3 / h, the temperature is 70°C, and then passes through the first cooler 8, the gas mixture is condensed to 40°C, the water in the gas will be condensed, and the condensed water will absorb the organic amines carried in the gas; after that, the steam-water mixture is separated by the gas-liquid separation tank 9, the water containing organic amines refluxes from the bottom of the gas-liquid separation tank 9 to the first regeneration tower 16 at a temperature of about 30°C, and the gas enters the desulfurization tower 12 from the top of the gas-liquid separation tank 9 at a temperature of 30°C.

[0072] Step 3.4: In the desulfurization tower 12, the H2S and CO2 mixed gas at 30°C flows upward from the bottom of the tower at a gas velocity of about 1m / s. The H2S in the mixed gas is selectively absorbed and removed by the bed filled with desulfurizer, and the pure CO2 at 25°C is absorbed at a velocity of 45Nm 3 / h is discharged from the top of the tower. The desulfurizer saturated with H2S is transferred to the second regeneration tower 13 for regeneration in an oxygen atmosphere at 65°C, and the resulting sulfur is collected and discharged from the bottom of the tower.

[0073] After repeated testing, it was found that in the utility model, the capture efficiency of CO2 can reach more than 90%, and the removal efficiency of sulfide can reach more than 90%.

[0074] Comparative Example 1

[0075] The only difference from Example 1 is that the hydrolysis tower 2 is removed, that is, the wet coal gas obtained by spraying directly enters the absorption tower 3, and the other steps and conditions are the same as those in Example 1.

[0076] The results showed that due to the removal of the hydrolysis step, the adsorption effect of organic sulfur was poor, desulfurization and decarbonization could not be achieved simultaneously, and the sulfide emission standards could not be met.

[0077] Comparative Example 2

[0078] The only difference from Example 1 is that the two flash tanks are removed, that is, the first rich liquid discharged from the absorption tower 3 directly enters the first regeneration tower 16, and the other steps and conditions are the same as those in Example 1.

[0079] The results showed that due to the removal of the reduced pressure evaporation step in the flash tank, H2S and CO2 could not be fully decomposed within the same time, and the final CO2 gas and sulfur output decreased, the removal efficiency decreased, and the decomposition energy consumption increased.

[0080] Compared with the prior art, the utility model has the following advantages:

[0081] (1) The utility model provides a process system suitable for simultaneously removing hydrogen sulfide and carbon dioxide from blast furnace gas. After being processed by this system, the pollutants in the blast furnace gas are purified, the calorific value and quality of the gas are improved, and high-purity CO2 can be obtained for downstream comprehensive utilization and sulfur slag products.

[0082] (2) The utility model combines the desulfurization and decarbonization process system with the low-grade heat source generated during the smelting process of the steel plant, and utilizes the blast furnace slag water as a heat source for heating the regeneration tower, thereby reducing the additional heat supply during the desulfurization and decarbonization process and reducing the operating cost of the system.

[0083] (3) The utility model utilizes a combination of chemical organic amines and iron oxide desulfurizers to achieve efficient separation of H2S and CO2 in blast furnace gas, helping the steel industry to reduce pollution and carbon emissions.

[0084] The specific implementation methods of the utility model described above do not constitute a limitation on the protection scope of the utility model. Any other corresponding changes and modifications made according to the technical concept of the utility model should be included in the protection scope of the claims of the utility model.

Claims

1. A system for collaboratively removing sulfide and carbon dioxide from blast furnace gas, characterized in that: It includes a spray tower, a hydrolysis tower, an absorption tower and a water washing tower connected in sequence. The spray tower is provided with a first spray device for spraying alkali solution to remove chloride ions in the coal gas; the hydrolysis tower is provided with a hydrolysis catalyst for catalyzing the hydrolysis of organic sulfur in the coal gas into H2S; the absorption tower is provided with a second spray device for spraying absorbent to absorb H2S and CO2 in the coal gas; the water scrubber is provided with a third spray device for spraying water; It also includes a regeneration and separation device for regenerating, separating and recovering the absorbent, H2S and CO2, and the regeneration and separation device is connected to the absorption tower.

2. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 1, characterized in that: The spray tower, hydrolysis tower, absorption tower and water washing tower are all provided with gas inlets and gas outlets, and are all bottom-in and top-out structures; the upper middle part of the absorption tower is provided with a gas intake port for taking gas to detect H2S and CO2 concentrations.

3. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 1, characterized in that: The regeneration and separation device comprises a flash tank, a gas-liquid separation tank, a first regeneration tower and a desulfurization tower, wherein an absorbent outlet is arranged at the bottom of the absorption tower and is connected to the flash tank through a pump; The top of the flash tank is connected to the inlet of the gas-liquid separation tank by setting a gas outlet, and the gas-liquid separation tank is connected to the desulfurization tower by setting a gas outlet. A desulfurization agent for absorbing H2S is arranged in the desulfurization tower, and a CO2 discharge outlet is arranged at the top of the desulfurization tower; The bottoms of the flash tank and the gas-liquid separation tank are respectively connected to the first regeneration tower by arranging liquid outlets.

4. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 3, characterized in that: The flash tanks include two, and the two flash tanks are arranged in parallel.

5. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 3, characterized in that: A liquid outlet is provided at the bottom of the absorption tower and is connected to the rich liquid inlet of the first lean and rich liquid heat exchanger through a rich liquid pump, and the rich liquid outlet of the first lean and rich liquid heat exchanger is connected to the side wall inlet of the flash tank; the liquid outlet at the bottom of the flash tank is connected to the rich liquid inlet of the second lean and rich liquid heat exchanger, and the rich liquid outlet of the second lean and rich liquid heat exchanger is connected to the upper spray inlet of the first regeneration tower through a rich liquid heater; a gas outlet is provided at the top of the first regeneration tower and is connected to the inlet of the gas-liquid separation tank through a first cooler, and the gas outlet at the top of the flash tank is also connected to the inlet of the gas-liquid separation tank through the first cooler; a liquid outlet is provided at the bottom of the first regeneration tower and is connected to the lean liquid inlet of the second lean and rich liquid heat exchanger through a lean liquid pump, the lean liquid outlet of the second lean and rich liquid heat exchanger is connected to the lean liquid inlet of the first lean and rich liquid heat exchanger, and the lean liquid outlet of the first lean and rich liquid heat exchanger is connected to the upper inlet of the absorption tower through the second cooler, so as to return the absorbent lean liquid to the absorption tower for reuse.

6. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 3, characterized in that: A liquid outlet is also provided at the bottom of the first regeneration tower and is connected to a reboiler. The reboiler is connected to an inlet of a lower side wall of the first regeneration tower, forming a loop for heating part of the absorbent.

7. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 3, characterized in that: It also includes a water storage tank for storing blast furnace slag flushing water. The flash tank is wrapped with a jacket, and the water storage tank is connected to the jacket to form a heating circuit.

8. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 7, characterized in that: The reboiler is connected to a heat source device, which includes a first heat exchanger for exchanging heat with a water storage tank and a second heat exchanger for exchanging heat with a high-temperature steam heat source.

9. The system for collaboratively removing sulfide and carbon dioxide from blast furnace gas according to claim 3, characterized in that: It also includes a second regeneration tower for regenerating and recycling the adsorption saturated desulfurizer.

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