Hydrogen production system from coke oven gas

Abstract

The application provides a coke oven gas hydrogen production system, which comprises a gas tank, a gas compression device, a carbon monoxide conversion device, a decarburization tower, a water washing tower, a desulfurization device, a water removal device, a hydrogen purification device and a hydrogen storage device connected in sequence. The system of the application converts the carbon monoxide in the coke oven gas after deep impurity removal into hydrogen through the cooperation of the above devices, improves the hydrogen yield in the process of producing hydrogen from coke oven gas, and overcomes the problem of low hydrogen yield caused by separating hydrogen and carbon monoxide in coke oven gas by temperature swing adsorption in the prior art.

Description

Technical Field

[0001] This application relates to the field of hydrogen production technology from coke oven gas, and more particularly to a hydrogen production system from coke oven gas. Background Technology

[0002] Coke oven gas is a combustible gas produced by the high-temperature dry distillation of coking coal in a coking unit. Generally, coke oven gas has undergone processes such as tar removal, benzene removal, desulfurization, ammonia removal, and naphthalene washing. Its yield and composition vary depending on the quality of the coking coal and the coking process parameters. Its main components are hydrogen (H2: 55%~60%) and methane (CH4: 23%~27%), with small amounts of carbon monoxide (CO: 5%~8%) and alkanes (C2). m H n Coke oven gas contains 2%~4% carbon dioxide (CO2: 1.5%~3%), nitrogen (N2: 3%~7%), and oxygen (O2: 0.3%~0.8%). Therefore, coke oven gas can be fully utilized to produce energy and chemical products, reducing the consumption of primary fossil fuels and optimizing the energy structure. With further upgrades in coke oven gas purification and utilization technologies, the development of high-value-added coke oven gas has broad prospects.

[0003] One way to utilize coke oven gas is to produce high-purity hydrogen for combustion. The existing method is to purify the coke oven gas through pretreatment methods such as adsorption and washing, and then send it into a temperature-switching adsorption tower to separate hydrogen and carbon monoxide in the gas through temperature-switching adsorption, thus obtaining hydrogen and purified gas with carbon monoxide as the main component. Obviously, the hydrogen production of this method is relatively low. Utility Model Content

[0004] This application provides a coke oven gas hydrogen production system to solve the problem of low hydrogen production caused by separating hydrogen and carbon monoxide in coke oven gas through temperature-switching adsorption in existing hydrogen production methods.

[0005] This application provides a coke oven gas hydrogen production system, comprising a gas holder, a gas compression device, a carbon monoxide conversion device, a decarbonization tower, a water washing tower, a desulfurization device, a water removal device, a hydrogen purification device, and a hydrogen storage device connected in series.

[0006] Optionally, the gas compression device includes a first compressor, an electrostatic precipitator, a filter, a benzene and naphthalene removal tower, and a second compressor connected in series.

[0007] Optionally, the carbon monoxide conversion device includes a mixer and at least one conversion furnace; The mixer is connected to the steam line and the second compressor, respectively. A first preheater is provided between the mixer and the second compressor.

[0008] Optionally, a water washing tank is provided between the second compressor and the first preheater.

[0009] Optionally, the desulfurization unit includes a first desulfurization tower, a tube side of a second preheater, a first heater, a second desulfurization tower, a shell side of a second preheater, a first adsorption tower, a tube side of a third preheater, a second heater, a third desulfurization tower, a shell side of a third preheater, a second adsorption tower, and a waste heat utilization device, all connected in series.

[0010] Optionally, the waste heat utilization device includes a waste heat boiler and a heat pump connected in series.

[0011] Optionally, the water removal device includes a cooler and a dehydration tower connected in series; The dehydration tower is filled with an alumina layer and a molecular sieve layer in sequence along the gas flow direction.

[0012] Optionally, the hydrogen purification unit includes a temperature-switching adsorption tower and a deoxygenation tower connected in series.

[0013] This application provides a coke oven gas hydrogen production system. By installing a carbon monoxide conversion device before the hydrogen purification unit to convert carbon monoxide into hydrogen, the system increases the hydrogen content while reducing the carbon monoxide content in the gas. Simultaneously, a decarbonization tower absorbs and removes the carbon dioxide generated during the carbon monoxide conversion process. The decarbonized crude hydrogen is then sent to a desulfurization and dehydration unit for further desulfurization and dehydration, thus preventing the inorganic and organic sulfides in the hydrogen from poisoning the catalyst used in the hydrogen purification process. Through the combined use of the above devices, this system converts carbon monoxide in deeply purified coke oven gas into hydrogen, increasing the hydrogen yield in the coke oven gas hydrogen production process. This overcomes the drawback of existing methods that rely solely on temperature-switching adsorption to separate hydrogen and carbon monoxide in coke oven gas, resulting in low hydrogen production. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A schematic diagram of a coke oven gas hydrogen production system provided in an embodiment of this application; Figure 2 This is a schematic diagram of a gas compression device provided in an embodiment of this application; Figure 3 A schematic diagram of a carbon monoxide conversion device provided in an embodiment of this application; Figure 4 This is a schematic diagram of a desulfurization device provided in one embodiment of this application; Figure 5 This is a schematic diagram of a water removal device provided in an embodiment of this application.

[0016] Explanation of reference numerals in the attached figures: 1. Gas holder; 2. Gas compression unit; 3. Carbon monoxide conversion unit; 4. Decarbonization tower; 5. Water washing tower; 6. Desulfurization unit; 7. Water removal unit; 8. Hydrogen purification unit; 9. Hydrogen storage unit; 10. Desorbed gas pipeline; 21. First compressor; 22. Electrostatic precipitator; 23. Filter; 24. Benzene and naphthalene removal tower; 25. Second compressor; 30. Steam pipeline; 31. Mixer; 32. Converter; 33. First preheater; 34. Equipped with a water washing tank; 60. 61. Steam recovery pipeline; 62. First desulfurization tower; 63. Second preheater; 64. First heater; 65. Second desulfurization tower; 66. First adsorption tower; 67. Third preheater; 68. Second heater; 69. Third desulfurization tower; 71. Second adsorption tower; 72. Cooler; 81. Dehydration tower; 82. Variable temperature adsorption tower; 610. Deoxygenation tower; 611. Waste heat utilization device; 612. Waste heat boiler; 721. Heat pump; 722. Alumina layer; 723. Molecular sieve layer. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0018] like Figure 1 As shown, this application provides a coke oven gas hydrogen production system, including a gas holder 1, a gas compression device 2, a carbon monoxide conversion device 3, a decarbonization tower 4, a water washing tower 5, a desulfurization device 6, a water removal device 7, a hydrogen purification device 8, and a hydrogen storage device 9 connected in series.

[0019] The hydrogen storage unit 9 includes a compressor and a high-purity hydrogen charging and discharging station connected in series.

[0020] In operation, the coke oven gas stored in gas holder 1 (which has been purified by previous stages of dust removal, oil removal, and naphthalene removal, at a pressure of approximately 0.28 MPa) is compressed and pressurized in gas compression device 2, and then transferred to carbon monoxide conversion device 3 for conversion, where the carbon monoxide in the gas is converted into carbon dioxide and hydrogen. The resulting gas (mainly a mixture of hydrogen and carbon dioxide) contains a large amount of carbon dioxide, which needs to be removed. The carbon dioxide-containing mixture is then passed into decarbonization tower 4, where an absorbent (propylene carbonate in this application) is used to absorb and remove the carbon dioxide. The decarbonized gas is then passed into water washing tower 5 for scrubbing with clean water to remove any remaining decarbonization absorbent. Finally, the washed crude hydrogen is transferred to desulfurization device 6 for desulfurization treatment.

[0021] Since water is produced by the reaction of hydrogen sulfide and zinc oxide absorbent during the desulfurization process, it needs to be removed. At this time, the cooled crude hydrogen gas is transferred to the dehydration device 7 for dehydration treatment.

[0022] The dehydrated crude hydrogen is then transferred to hydrogen purification unit 8, where trace impurities such as CO, CO2, hydrocarbons, and water are adsorbed from the crude hydrogen using temperature-switching adsorption to produce hydrogen. The hydrogen that has undergone temperature-switching adsorption is then deoxygenated to obtain high-purity hydrogen. At this point, high-purity hydrogen with a purity >99.999% and a dew point <-60℃ can be obtained. This high-purity hydrogen is then transferred to hydrogen storage unit 9 for storage.

[0023] This application provides a coke oven gas hydrogen production system. A carbon monoxide conversion device 3 is installed before the hydrogen purification unit 8 to convert carbon monoxide into hydrogen, increasing the hydrogen content while reducing the carbon monoxide content in the gas. Simultaneously, a decarbonization tower 4 absorbs and removes the CO2 generated during the carbon monoxide conversion process. The decarbonized crude hydrogen is then sent to a desulfurization unit 6 and a dehydration unit 7 for further desulfurization and dehydration, preventing the inorganic and organic sulfides in the hydrogen from poisoning the catalyst used in the hydrogen purification process. Through the combined use of the above devices, this system converts carbon monoxide in deeply purified coke oven gas into hydrogen, increasing the hydrogen yield in the coke oven gas hydrogen production process. This overcomes the drawback of existing methods that rely solely on temperature-switching adsorption to separate hydrogen and carbon monoxide in coke oven gas, resulting in low hydrogen yield.

[0024] like Figure 2 As shown, optionally, the gas compression device 2 includes a first compressor 21, an electrostatic precipitator 22, a filter 23, a benzene and naphthalene removal tower 24, and a second compressor 25 connected in series.

[0025] After being compressed by the first compressor 21 (which is a screw compressor) to a pressure of approximately 0.8~1.2 MPa, the compressed gas further passes through an electrostatic precipitator 22 to capture and remove tar. The tar-free compressed gas then enters a filter 23 (such as a precision filter, also known as a security filter) to remove any remaining tar droplets and fine particulate matter. The gas filtered by filter 23 is then fed into a benzene and naphthalene removal tower 24, where adsorbent packing removes impurities such as benzene, naphthalene, NH3, H2S, and hydrocarbons with C5 or higher. The gas processed by the benzene and naphthalene removal tower 24 then enters a second compressor 25 (which is a reciprocating compressor) for further compression. The compressed gas can then be sent to subsequent processing stages.

[0026] like Figure 3 As shown, optionally, the carbon monoxide conversion device 3 includes a mixer 31 and at least one conversion furnace 32; The mixer 31 is also connected to the steam line 30 and the second compressor 25, respectively; A first preheater 33 is provided between the mixer 31 and the second compressor 25.

[0027] The coal gas, compressed by the second compressor 25, is fed into the first preheater 33 and heated to 180~220°C. It is then mixed with steam from the steam pipeline 30 in the mixer 31 and fed into the converter 32. Under the catalytic action of the catalyst in the converter 32, carbon monoxide and water in the coal gas undergo the following reaction to produce carbon dioxide and hydrogen: CO + H2O → CO2 + H2. The gas obtained after the conversion is mainly a mixture of hydrogen and carbon dioxide.

[0028] like Figure 3 As shown, optionally, a water washing tank 34 is provided between the second compressor 25 and the first preheater 33.

[0029] In this application, even if the gas may still contain trace amounts of particulate impurities after the previous filtration, it is first transferred to the water washing tank 34 for aeration washing to wash away some dust and other particles in the gas and increase the water content in the gas.

[0030] like Figure 4 As shown, optionally, the desulfurization device 6 includes a first desulfurization tower 61, the tube side of the second preheater 62, a first heater 63, a second desulfurization tower 64, the shell side of the second preheater 62, a first adsorption tower 65, the tube side of the third preheater 66, a second heater 67, a third desulfurization tower 68, the shell side of the third preheater 66, a second adsorption tower 69, and a waste heat utilization device 610, connected in series.

[0031] During desulfurization in desulfurization unit 6, crude hydrogen gas is first introduced into the first desulfurization tower 61, where an absorbent is used to absorb and remove inorganic sulfides (hydrogen sulfide, sulfur dioxide, etc.) from the crude hydrogen gas. This can be achieved using the tannin method in wet desulfurization. Since the coal gas also contains organic sulfur compounds such as thiophene, thiazole, and thiophenol, these sulfides are difficult to remove through traditional absorption desulfurization. Therefore, hydrodesulfurization is necessary to react the organic sulfur compounds with hydrogen to form hydrogen sulfide, which is then adsorbed and removed. Since hydrodesulfurization requires high-temperature conditions (200~300℃), the crude hydrogen gas, after absorption desulfurization in the first desulfurization tower 61, is first heated by heat exchange in the second preheater 62, and then enters the first heater 63 to be heated to a preset reactivity temperature (e.g., 250℃). The heated crude hydrogen gas is then fed into the second desulfurization tower 64, where, under the action of a catalyst, the organic sulfur compounds in the crude hydrogen gas undergo a hydrogenation reaction with the hydrogen, converting the organic sulfur compounds into hydrogen sulfide and hydrocarbons. The crude hydrogen gas, after catalytic secondary desulfurization, exits from the second desulfurization tower 64 and re-enters the shell side of the second preheater 62 to exchange heat with the crude hydrogen gas in the tube side after desulfurization in the first desulfurization tower 61. The heat-exchanged secondary desulfurized crude hydrogen gas then enters the first adsorption tower 65, where it reacts with the adsorbent zinc oxide to produce zinc sulfide and water, removing the hydrogen sulfide produced during the secondary desulfurization process. The hydrogen gas then enters the third preheater 66 for heat exchange and is heated by the second heater 67. It then enters the third desulfurization tower 68 for three desulfurization processes. After three desulfurization processes, the hydrogen gas enters the second adsorption tower 69 for hydrogen sulfide removal after heat exchange in the third preheater 66.

[0032] like Figure 4 As shown, optionally, the waste heat utilization device 610 includes a waste heat boiler 611 and a heat pump 612 connected in series.

[0033] Since the crude hydrogen gas is heated to a high temperature during the pre-catalytic hydrodesulfurization process, the temperature of the desulfurized crude hydrogen gas after adsorption treatment in the second adsorption tower 69 is relatively high. If this heat in the gas is not recovered, it will result in energy waste and is not conducive to the subsequent water removal process. Therefore, the high-temperature crude hydrogen gas after desulfurization is sequentially fed into the waste heat boiler 611 and the heat pump 612 to recover the heat in each stage and achieve the cooling of the crude hydrogen gas.

[0034] like Figure 5 As shown, optionally, the dehydration device 7 includes a cooler 71 and a dehydration tower 72 connected in series. The dehydration tower 72 is filled with an alumina layer 721 and a molecular sieve layer 722 in sequence along the gas flow direction.

[0035] In this application, water is produced by the reaction of hydrogen sulfide and zinc oxide absorbent during the desulfurization process, which needs to be removed. The cooled crude hydrogen gas is then transferred to the dehydration device 7 for dehydration treatment. In the dehydration device 7, the crude hydrogen gas is first passed through a cooler 71 to cool to below 40°C, and then transferred to a dehydration tower 72, where it is absorbed and dehydrated by the alumina layer 721 and the molecular sieve layer 722.

[0036] like Figure 1 As shown, optionally, the hydrogen purification device 8 includes a temperature-switching adsorption tower 81 and a deoxygenation tower 82 connected in series.

[0037] In this application, the crude hydrogen gas after dehydration needs to be refined. At this time, the dehydrated crude hydrogen gas is transferred to the temperature-switching adsorption tower 81, where the trace impurity gases such as CO, CO2, hydrocarbons, and water in the crude hydrogen gas are adsorbed by temperature-switching adsorption and hydrogen gas is output. Then, the hydrogen gas after temperature-switching adsorption is passed into the deoxygenation tower 82. Under the action of a catalyst, the hydrogen gas reacts with trace amounts of oxygen to produce water and remove the oxygen. At this time, high-purity hydrogen gas with a purity >99.999% can be obtained. This high-purity hydrogen gas is transferred to the hydrogen storage device 9 for storage.

[0038] In operation, the coke oven gas stored in gas holder 1 (which has been purified by previous stages of dust removal, oil removal, and naphthalene removal, at a pressure of approximately 0.28 MPa) is compressed by the first compressor 21 (a screw compressor) to a pressure of approximately 0.8~1.2 MPa. The compressed gas then passes through an electrostatic precipitator 22 to further remove tar. The tar-free compressed gas then enters a filter 23 to remove any remaining tar droplets and fine particles. The filtered gas is then fed into a benzene and naphthalene removal tower 24, where adsorbent packing removes impurities such as benzene, naphthalene, NH3, H2S, and hydrocarbons with C5 or higher concentrations. After treatment in the benzene and naphthalene removal tower 24, the gas enters a second compressor 25 (a reciprocating compressor) for further compression. The compressed gas then enters a carbon monoxide conversion device 3 to convert carbon monoxide into carbon dioxide and hydrogen. Specifically, the compressed coal gas is first transferred to a water washing tank 34 for aeration washing to remove dust and other particles while increasing the water content. The washed coal gas is then fed into a first preheater 33 and heated to 180-220°C. It is then mixed with steam from steam pipeline 30 in a mixer 31 and fed into a converter 32. In the converter 32, under the catalytic action of the catalyst, carbon monoxide and water in the coal gas react to produce carbon dioxide and hydrogen: CO + H₂O → CO₂ + H₂. The resulting gas (mainly a mixture of hydrogen and carbon dioxide) contains a large amount of carbon dioxide, which needs to be removed. This carbon dioxide-containing mixture is then fed into a decarbonization tower 4, where an absorbent (propylene carbonate in this application) is used to absorb and remove the carbon dioxide. Finally, the washed and decarbonized gas is fed into a water washing tower 5 for spray washing with clean water to remove the decarbonization absorbent. The washed crude hydrogen gas is then transferred to desulfurization unit 6 for desulfurization treatment.

[0039] During desulfurization in desulfurization unit 6, crude hydrogen gas is first introduced into the first desulfurization tower 61, where an absorbent is used to absorb and remove inorganic sulfides (hydrogen sulfide, sulfur dioxide, etc.) from the crude hydrogen gas. This can be achieved using the tannin method in wet desulfurization. Since the coal gas also contains organic sulfur compounds such as thiophene, thiazole, and thiophenol, these sulfides are difficult to remove through traditional absorption desulfurization. Therefore, hydrodesulfurization is necessary to react the organic sulfur compounds with hydrogen to form hydrogen sulfide, which is then adsorbed and removed. Since hydrodesulfurization requires high-temperature conditions (200~300℃), the crude hydrogen gas, after absorption desulfurization in the first desulfurization tower 61, is first heated by heat exchange in the second preheater 62, and then enters the first heater 63 to be heated to a preset reactivity temperature (e.g., 250℃). The heated crude hydrogen gas is then fed into the second desulfurization tower 64. Under the action of a catalyst, the organic sulfur compounds in the crude hydrogen gas undergo a hydrogenation reaction with the hydrogen gas, converting the organic sulfur compounds into hydrogen sulfide and hydrocarbons. The crude hydrogen gas, after catalytic secondary desulfurization, exits from the second desulfurization tower 64 and re-enters the shell side of the second preheater 62 to exchange heat with the crude hydrogen gas in the tube side after desulfurization in the first desulfurization tower 61. The heat-exchanged secondary desulfurized crude hydrogen gas then enters the first adsorption tower 65, where it reacts with the adsorbent zinc oxide to produce zinc sulfide and water, removing the hydrogen sulfide produced during the secondary desulfurization process. The hydrogen gas then enters the third preheater 66 for heat exchange and is heated by the second heater 67. It then enters the third desulfurization tower 68 for three stages of desulfurization. After further heat exchange in the third preheater 66, the desulfurized hydrogen gas enters the second adsorption tower 69 to remove hydrogen sulfide. At this point, the crude desulfurized hydrogen gas is at a relatively high temperature. It is then sequentially fed into the waste heat boiler 611 and the heat pump 612 to recover its heat and cool the crude hydrogen gas.

[0040] Since water is produced by the reaction of hydrogen sulfide and zinc oxide absorbent during the desulfurization process, it needs to be removed. The cooled crude hydrogen gas is then transferred to the dehydration device 7 for dehydration treatment. In the dehydration device 7, the crude hydrogen gas is first passed through a cooler 71 to cool to below 40°C, and then transferred to a dehydration tower 72, where it is absorbed and dehydrated by the alumina layer 721 and the molecular sieve layer 722.

[0041] The dehydrated crude hydrogen is then transferred to a temperature-switched adsorption tower 81, where trace impurities such as CO, CO2, hydrocarbons, and water are adsorbed to produce hydrogen. The hydrogen after temperature-switched adsorption is then passed into a deoxygenation tower 82, where a catalyst reacts the hydrogen with trace amounts of oxygen to produce water, thus removing the oxygen. This yields high-purity hydrogen with a purity >99.999%, which is then transferred to a hydrogen storage device 9 for storage.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A coke oven gas hydrogen production system, characterized in that, It includes a gas holder (1), a gas compression device (2), a carbon monoxide conversion device (3), a decarbonization tower (4), a water washing tower (5), a desulfurization device (6), a water removal device (7), a hydrogen purification device (8), and a hydrogen storage device (9) connected in series.

2. The coke oven gas hydrogen production system according to claim 1, characterized in that, The gas compression device (2) includes a first compressor (21), an electrostatic precipitator (22), a filter (23), a benzene and naphthalene removal tower (24), and a second compressor (25) connected in series.

3. The coke oven gas hydrogen production system according to claim 2, characterized in that, The carbon monoxide conversion device (3) includes a mixer (31) and at least one converter (32). The mixer (31) is connected to the steam line (30) and the second compressor (25) respectively; A first preheater (33) is provided between the mixer (31) and the second compressor (25).

4. The coke oven gas hydrogen production system according to claim 3, characterized in that, A water washing pool (34) is provided between the second compressor (25) and the first preheater (33).

5. The coke oven gas hydrogen production system according to claim 1, characterized in that, The desulfurization unit (6) includes a first desulfurization tower (61), the tube side of the second preheater (62), a first heater (63), a second desulfurization tower (64), the shell side of the second preheater (62), a first adsorption tower (65), the tube side of the third preheater (66), a second heater (67), a third desulfurization tower (68), the shell side of the third preheater (66), a second adsorption tower (69), and a waste heat utilization device (610) connected in series.

6. The coke oven gas hydrogen production system according to claim 5, characterized in that, The waste heat utilization device (610) includes a waste heat boiler (611) and a heat pump (612) connected in series.

7. The coke oven gas hydrogen production system according to claim 1, characterized in that, The dehydration device (7) includes a cooler (71) and a dehydration tower (72) connected in series. The dehydration tower (72) is filled with an alumina layer (721) and a molecular sieve layer (722) in sequence along the gas flow direction.

8. The coke oven gas hydrogen production system according to any one of claims 1-7, characterized in that, The hydrogen purification device (8) includes a temperature-switching adsorption tower (81) and a deoxygenation tower (82) connected in series.

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