Method for synthesizing methane from coke oven gas with high carbon-hydrogen ratio

Abstract

The invention provides a method for synthesizing methane from coke oven gas with a high carbon-hydrogen ratio, which comprises the following steps of: after starting for a period of time, deeply purifying the coke oven gas with the high carbon-hydrogen ratio, and dividing the coke oven gas into two paths: feeding outlet gas subjected to heat recovery and pressurization of a first path and a second-stage methanation reactor into a first-stage methanation reactor; the second path is mixed with outlet gas of the first-stage methanation reactor after heat recovery and enters a second-stage methanation reactor; outlet gas of the secondary methanation reactor is subjected to heat recovery and heat exchange and then enters a first gas-liquid separator; the outlet gas of the first gas-liquid separator is divided into two streams, one stream is mixed with the deeply purified coke oven gas after being pressurized and subjected to heat exchange, and the mixture enters a first-stage methanation reactor; and the other part of the gas enters the third-stage methanation reactor after exchanging heat with the outlet gas of the third-stage methanation reactor, and the gas at the outlet of the third-stage methanation reactor enters the ammonia washing tower after being subjected to heat exchange cooling and gas-liquid separation. The method is low in investment and low in energy consumption, and the total content of oxycarbide in the obtained product is low.

Description

Technical Field

[0001] The invention relates to the field of industrial methane synthesis, and in particular to a method for synthesizing methane from high carbon-hydrogen ratio coke oven gas. Background Art

[0002] my country's energy structure is mainly coal, with oil and natural gas accounting for a relatively small proportion, far below the world average. As a clean energy, natural gas has seen an increasing market consumption year by year, and the prospects for the entire industry are quite promising.

[0003] Coke oven gas is a combustible gas byproduct produced during the coal coking process. Using its relatively low cost advantage to produce LNG has a good development momentum in unconventional natural gas projects. However, the current global economic situation and the coal coking industry have entered the stock market competition from the incremental market competition. This change in market conditions requires coking enterprises to implement refined management, optimize coal blending technology, and reduce costs, resulting in a higher carbon content and a relatively lower hydrogen content in the coke oven gas on the market. Compared with the gas composition of traditional coke oven gas, it has a higher carbon-to-hydrogen ratio (high carbon-to-hydrogen ratio coke oven gas). CO and CO in traditional coke oven gas 2 The total content is 8% to 12%, CO and CO in coke oven gas with high carbon-hydrogen ratio 2 The total content exceeds 12%, usually reaching 12% to 16%. The methanation reaction of high carbon-hydrogen ratio coke oven gas will generate more heat and require more hydrogen. In addition, due to the excessive heat release, in order to protect the catalyst, it is necessary to increase the circulating gas volume to reduce the temperature of the reactor, and increasing the circulating volume will increase the energy consumption of the system. In addition, when the high carbon-hydrogen ratio coke oven gas is methanated, in order to ensure that the CO and CO entering the deep cold separation device 2 If the total content is less than 50ppm, increasing the product yield requires more process flows and equipment, which results in higher investment costs.

[0004] Therefore, it is necessary to provide a method for synthesizing methane with low investment, low comprehensive energy consumption and high product yield for high carbon-hydrogen ratio coke oven gas, and obtain CO and CO 2 High methane content gas with a total content of less than 50ppm. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for synthesizing methane from coke oven gas with a high carbon-hydrogen ratio, which has the advantages of low investment, low comprehensive energy consumption, high product yield, etc., and the obtained high methane content gas contains CO and CO 2 The total content is less than 50ppm.

[0006] The embodiment of the present invention provides a method for synthesizing methane from coke oven gas with a high carbon-to-hydrogen ratio, comprising: The high carbon-to-hydrogen ratio coke oven gas is treated to remove sulfur, naphthalene, benzene and tar impurities, and then hydrogenated to remove organic sulfur to obtain deeply purified coke oven gas, which is sent to the methanation process; In the methanation process, after a period of operation, the deeply purified coke oven gas is divided into two paths. The first path and the circulating gas pressurized by the circulating gas compressor from the outlet of the secondary methanation reactor enter the primary methanation reactor for reaction. The outlet gas of the primary methanation reactor recovers heat through the first waste heat boiler, and then is mixed with the second path of deeply purified coke oven gas and enters the secondary methanation reactor for reaction. The outlet gas of the secondary methanation reactor recovers heat through the second waste heat boiler, and then exchanges heat with the high carbon-hydrogen ratio coke oven gas in the coke oven gas preheater, and then exchanges heat with the circulating gas in the circulating gas heat exchanger. The circulating gas after being pressurized by the ring gas compressor is heat exchanged, and finally cooled by the first heat exchanger before entering the first gas-liquid separator; the outlet gas from the first gas-liquid separator is divided into two streams, one of which is heat exchanged with the outlet gas of the secondary methanation reactor after being pressurized by the circulating gas compressor, and then mixed with a deeply purified coke oven gas and enters the primary methanation reactor; the other stream is heat exchanged with the outlet gas of the tertiary methanation reactor in the inlet and outlet heat exchangers and then enters the tertiary methanation reactor, the outlet gas of the tertiary methanation reactor is cooled by the second heat exchanger and enters the second gas-liquid separator to separate water and then enters the ammonia washing tower.

[0007] As one method, the process for obtaining deeply purified coke oven gas is as follows: the coke oven gas from which sulfur, naphthalene, benzene and tar impurities have been removed is pressurized and then enters a coke oven gas preheater for preheating, and then enters a pre-hydrogenation reactor and a primary hydrogenation reactor in sequence for a primary hydrogenation reaction of organic sulfur and unsaturated hydrocarbons in the coke oven gas, then enters a first solid desulfurization catalyst reactor for a primary removal of hydrogen sulfide, then enters a secondary hydrogenation reactor for a secondary hydrogenation reaction of organic sulfur, and then continues to enter a second solid desulfurization catalyst reactor for a secondary removal of hydrogen sulfide.

[0008] As a method, the deeply purified coke oven gas is divided into two paths, the first path accounts for 0.5 to 0.9 of the flow rate of the total coke oven gas; the gas flow rate ratio of the circulating gas to the coke oven gas is 0.50 to 2.50.

[0009] As a method, the first route is mixed with the circulating gas from the outlet of the secondary methanation reactor after being pressurized by the circulating gas compressor, and the temperature is 280-320°C, and it enters the primary methanation reactor for reaction. The outlet gas recovers heat to 240-280°C through the first waste heat boiler, and then is mixed with the second route coke oven gas. The temperature after mixing is 280-320°C and enters the secondary methanation reactor for reaction. The outlet gas first recovers heat to 260-280°C through the second waste heat boiler, and then is heat exchanged with the pressurized coke oven gas raw gas that is about to enter the deep desulfurization process in the coke oven gas preheater to 200-220°C, and then heat exchanged with the circulating gas pressurized by the circulating gas compressor in the circulating gas heat exchanger, and finally cooled to 40-110°C through the first heat exchanger before entering the first gas-liquid separator.

[0010] As a method, the outlet gas from the first gas-liquid separator is divided into two streams, one of which is pressurized by the circulating gas compressor and then heat exchanged with the outlet gas of the secondary methanation reactor to 180-250°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor to 230-280°C through the inlet and outlet heat exchangers and enters the tertiary methanation reactor for reaction.

[0011] As a method, the coke oven gas from which sulfur, naphthalene, benzene and tar impurities have been removed is pressurized to 2.8-3.5 MPa and then enters the coke oven gas preheater for preheating to 240-280°C.

[0012] As a way to deeply purify H in coke oven gas 2 The sulfur content is less than 0.1ppm.

[0013] As a method, the operating temperature of the first solid desulfurization catalyst reactor and the second solid desulfurization catalyst reactor is 320°C to 450°C, the space velocity is 500 to 3000h-1, and the operating pressure is 2.8 to 3.5MPa.

[0014] As one approach, supplementary hydrogen-rich gas is added at the inlet of the second cylinder of the compressor for increasing the pressure of the coke oven gas or at the inlet of the secondary methanation reactor.

[0015] As a method, the raw gas composition of the high carbon-hydrogen ratio coke oven gas includes, in mole percentage, 48.7% to 57.5% H 2 , 20.1%~24.6% CH 4 3.5% to 8.3% N 2 , 0.55%~0.83% C 2 H 6 , 0.20%~0.85%O 2 1.95%~2.75% C 2 H4 , 9.7% to 11.3% CO, 0 to 0.12% C 3 H 8 , 3.3% to 4.8% CO 2 and 0~0.7% C 3 H 6 .

[0016] Compared with the prior art, the present invention has the following advantages: 1. The present invention provides a method for synthesizing methane from coke oven gas with a high carbon-hydrogen ratio, which has low investment, low comprehensive energy consumption, and high product yield. 2 A high methane content gas product with a total content of less than 50ppm.

[0017] 2. In the method for synthesizing methane from high carbon-hydrogen ratio coke oven gas provided by the present invention, the coke oven gas does not need to undergo cooling and heating in the fine desulfurization process. The raw gas directly enters the methanation process after high-temperature fine desulfurization, which simplifies the operating process and reduces investment.

[0018] 3. The present invention reduces the emission of harmful substances by deeply purifying and efficiently utilizing coke oven gas with a high carbon-to-hydrogen ratio. At the same time, the production and use of methane as a clean energy source is conducive to reducing greenhouse gas emissions, meeting the requirements of environmental protection and sustainable development and complying with green environmental protection processes.

[0019] 4. The present invention combines the ingenious design of the primary, secondary and tertiary methanation reactors with the overall process, while taking into account the cost and energy consumption, it also realizes the multi-stage methanation reaction, improves the selectivity and yield of methane, and the final methane product is purer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0021] Figure 1 It is a schematic diagram of the operating system of the method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to the present invention.

[0022] Markings in the figure: 1. pre-hydrogenation reactor 2. primary hydrogenation reactor 3. first solid desulfurization catalyst reactor 4. secondary hydrogenation reactor 5. second solid desulfurization catalyst reactor 6. primary methanation reactor 7. first waste heat boiler 8. secondary methanation reactor 9. second waste heat boiler 10. coke oven gas preheater 11. circulating gas heat exchanger 12. first heat exchanger 13. first gas-liquid separator 14. circulating gas compressor 15. inlet and outlet heat exchanger 16. tertiary methanation reactor 17. second heat exchanger 18. second gas-liquid separator 19. ammonia washing tower. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] As an example, the method for synthesizing methane from high carbon-hydrogen ratio coke oven gas of the present invention is specifically as follows: Figure 1 The system is shown in the figure. The system consists of the following: A system for synthesizing methane from high carbon-hydrogen ratio coke oven gas, comprising a deep purification unit for removing sulfur, naphthalene, benzene and tar impurities in the high carbon-hydrogen ratio coke oven gas, and a methanation unit for performing a methanation reaction; The methanation unit includes a primary methanation reactor 6, a secondary methanation reactor 8 and a tertiary methanation reactor 16; the air inlet of the primary methanation reactor 6 is connected to the air outlet of the deep purification unit, the air outlet of the primary methanation reactor 6 is connected to the air inlet of the secondary methanation reactor 8 through the first waste heat boiler 7, and the air outlet of the secondary methanation reactor 8 is connected to the first gas waste heat boiler 9, the coke oven gas preheater 10, the circulating gas heat exchanger 11, the first heat exchanger 12 and the first gas waste heat boiler 9. Liquid separator 13; the gas outlet of the first gas-liquid separator 13 is connected to the gas inlet of the tertiary methanation reactor 16 through a branch through the inlet and outlet heat exchanger 15, and is connected to the gas inlet of the primary methanation reactor 6 through another branch in sequence through the circulating gas compressor 14 and the circulating gas heat exchanger 11; the gas outlet of the tertiary methanation reactor 16 is connected to the ammonia washing tower 19 through the inlet and outlet heat exchanger 15, the second heat exchanger 17, and the second gas-liquid separator 18; the gas outlet of the ammonia washing tower 19 is connected to the deep cold separation section.

[0025] As a method, the gas outlet of the deep purification unit is divided into two paths, the first path is connected to the other branch of the first gas-liquid separator 13, and the second path is connected to the pipeline connecting the gas outlet of the first methanation reactor 6 to the gas inlet of the second methanation reactor 8.

[0026] As one approach, the hydrogen-rich gas obtained in the cryogenic separation stage is circulated through a pressurizing device and connected to the air inlet of the secondary methanation reactor 8, or is connected to the second-stage inlet of the compressor for pressurizing the coke oven gas without a pressurizing device.

[0027] As a method, the deep purification unit includes a pre-hydrogenation reactor 1, a primary hydrogenation reactor 2, a first solid desulfurization catalyst reactor 3, a secondary hydrogenation reactor 4 and a second solid desulfurization catalyst reactor 5 which are connected in sequence; the high carbon-hydrogen ratio coke oven gas feeding device is connected to the air inlet of the pre-hydrogenation reactor 1 via a compressor and a coke oven gas preheater 10, and the air outlet of the second solid desulfurization catalyst reactor 5 is divided into two paths, the first path is connected to the other branch of the first gas-liquid separator 13, and the second path is connected to the pipeline connecting the air outlet of the first methanation reactor 6 to the air inlet of the secondary methanation reactor 8.

[0028] As a method, a liquid inlet connected to a desalted water conveying device is provided at the upper portion of the ammonia washing tower 19, an air outlet is provided at the top, and a liquid outlet is provided at the bottom.

[0029] The condensate outlet at the bottom of the second gas-liquid separator 18 is connected to the plant's circulating water system or the plant's sewage treatment system. The liquid outlet at the bottom of the ammonia washing tower 19 is connected to the plant's sewage treatment system.

[0030] The basic steps and process of the method for synthesizing methane from high carbon-hydrogen ratio coke oven gas are as follows: The coke oven gas after desulfurization, naphthalene removal, benzene removal and tar and other impurities enters the deep desulfurization coke oven gas preheater 10 for preheating after being pressurized by the compressor, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out the primary hydrogenation reaction of organic sulfur and unsaturated hydrocarbons in the coke oven gas, and then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, and then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide, and the deeply purified coke oven gas (H in the gas) is obtained. 2 S content is less than 0.1ppm) enters the methanation process; In the methanation process, after nitrogen purging at the beginning of the start-up, the deeply purified coke oven gas is introduced into the primary methanation reactor 6 to react for a period of time (the length of time is not counted, as long as the outlet of the secondary methanation reactor 8 starts to output reaction gas), and the outlet gas of the primary methanation reactor 6 enters the secondary methanation reactor 8 through the first waste heat boiler 7 to continue the reaction; after starting for a period of time, the deeply purified coke oven gas is divided into two paths, the first path and the circulating gas from the outlet of the secondary methanation reactor 8 pressurized by the circulating gas compressor 14 enter the primary methanation reactor 6 for reaction, the outlet gas recovers heat through the first waste heat boiler 7, and then is mixed with the second path of deeply purified coke oven gas and enters the secondary methanation reactor 8 for reaction, the outlet gas of the secondary methanation reactor 8 first recovers heat through the second waste heat boiler 9, and then is mixed with the outlet gas to be entered The coke oven gas raw gas of the deep desulfurization process is heat exchanged in the coke oven gas preheater 10, and then heat exchanged with the circulating gas after being pressurized by the circulating gas compressor 14 in the circulating gas heat exchanger 11, and finally cooled by the first heat exchanger 12 and entered the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8, and then mixed with the deeply purified coke oven gas and enters the inlet of the primary methanation reactor 6; the other stream is heat exchanged with the outlet gas of the tertiary methanation reactor 16 in the inlet and outlet heat exchangers 15 and then enters the tertiary methanation reactor 16 for reaction. In this way, the outlet gas is first heat exchanged with the inlet gas to recover heat, and then cooled by the second heat exchanger 17 and enters the second gas-liquid separator 18 to separate water, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to wash away impurities such as trace ammonia contained in the gas, and then goes to the deep cold separation process.

[0031] In this case, supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 70% to 80%) is added at the inlet of the second cylinder of the compressor for increasing the pressure of the coke oven gas or at the inlet of the secondary methanation reactor 8 .

[0032] Based on the above basic steps and processes, the present invention further optimizes the process parameters to obtain the following more excellent solution.

[0033] The coke oven gas that has been desulfurized, denaphthalened, debenzened and detared is compressed to 2.8-3.5MPa by a compressor and then enters the deep desulfurized coke oven gas preheater 10 to be preheated to 240-280°C. It then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. It then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, and then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; as an example, the operating temperature is 350-450°C, and the air velocity is 500-3000h -1 , the operating pressure is 2.8-3.5 MPa, the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1 ppm, and then enters the methanation process.

[0034] In the method of the present invention, the coke oven gas does not need to undergo cooling and heating heat exchange in the fine desulfurization process, and directly enters the methanation process after high-temperature fine desulfurization, which saves processes, improves energy utilization efficiency, reduces energy waste, and helps reduce production costs.

[0035] The above steps firstly deeply purify the coke oven gas to remove impurities such as sulfur, naphthalene, benzene and tar, thus ensuring the smooth progress of the subsequent methanation reaction and avoiding the poisoning of the catalyst and the corrosion of the reactor by impurities, thereby improving the stability and efficiency of the overall process.

[0036] The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.5-0.9) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 0.50-2.50) at a temperature of 280-320°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 240-280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 280-320°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 260-280°C through the second waste heat boiler 9, and then mixes with the gas to be entered into the deep desulfurization process. The coke oven gas raw gas is heat exchanged to 200-220°C in the coke oven gas preheater 10, and then heat exchanged with the circulating gas after being pressurized by the circulating gas compressor 11 and the circulating gas compressor 14, and finally cooled to 40-110°C by the first heat exchanger 12 before entering the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 180-250°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 to 230-280°C through the inlet and outlet heat exchangers 15, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after being cooled by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0037] The above method uses a circulating gas compressor and a circulating gas heat exchanger to realize the recycling of the reaction gas, which not only improves the methane yield, but also reduces the consumption of raw gas, further reducing the production cost. At the same time, the recycling also helps to maintain the stable operating conditions of the reactor.

[0038] In the above method, the gas-liquid separator and the heat exchanger make the whole process more flexible, and it is convenient to adjust the operating parameters such as temperature, pressure and flow rate according to actual needs to adapt to different production needs.

[0039] In this case, supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 70% to 80%) is added at the inlet of the second cylinder of the compressor for increasing the pressure of the coke oven gas or at the inlet of the secondary methanation reactor 8 .

[0040] As an example, the hydrogenation catalyst used in the pre-hydrogenation reactor 1 is any iron-molybdenum catalyst sold on the market. The hydrogenation catalyst used in the primary hydrogenation reactor 2 and the secondary hydrogenation reactor 4 is a nickel-molybdenum catalyst supported by alumina, wherein, by mass fraction, Al 2O 3 ≥75%, NiO 3%~5%, MoO 3 11%~13%, the rest are additives.

[0041] As an example, the solid desulfurization catalyst used in the first solid desulfurization catalyst reactor 3 and the second solid desulfurization catalyst reactor 5 is a zinc-copper catalyst, wherein, by mass fraction, ZnO>95%, CuO≥0.5%, and the remainder is an additive.

[0042] As an example, the composition of the methanation catalyst used in the primary methanation reactor 6, the secondary methanation reactor 8 and the tertiary methanation reactor 16 is calculated by mass fraction as follows: NiO 45% to 60%, Al 2 O 3 28%~42.5%, TiO3%~8%, rare earth elements 3.5%~4.5%.

[0043] It should be noted that the components of the above catalyst are only used as an example and are not intended to unduly limit the scope of protection of the method of the present invention. Technicians can also use other similar catalysts sold on the market without affecting the basic effects of the present invention.

[0044] As an example, the composition of the coke oven gas used in the present invention is as follows: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 48.7～57.5 3.5～8.3 0.20～0.85 9.7～11.3 3.3～4.8 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 20.1～24.6 0.55～0.83 1.95～2.75 0～0.12 0～0.7 Several specific operation cases are provided below as reference and to assist understanding, but they are not exhaustive of the technical solutions of the present invention.

[0045] Example 1 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 55.5 5.34 0.40 10.48 4.02 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.40 0.67 2.13 0.01 0.05 The coke oven gas that has been desulfurized, denaphthalened, debenzened and detared is pressurized to 2.8MPa by a compressor and then enters the deep desulfurized coke oven gas preheater 10 to be preheated to 240°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. Among them, it then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, and then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; the operating temperature is 350°C, the air velocity is 500h-1, the operating pressure is 2.8MPa, and the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1ppm, and then enters the methanation process; The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.7) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 1.49) at a temperature of 280°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 283°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw gas that will enter the deep desulfurization process in the coke oven. The gas preheater 10 is heat exchanged to 200-220°C, and then heat exchanged with the circulating gas after the circulating gas compressor 11 and the circulating gas compressor 14 are pressurized, and finally cooled to 90-110°C by the first heat exchanger 12 and enter the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 232°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 through the inlet and outlet heat exchanger 15 to 230-240°C, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after cooling by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0046] Supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 70%) is added at the inlet of the second cylinder of the compressor for increasing the pressure of the coke oven gas or at the inlet of the secondary methanation reactor 8 .

[0047] The first waste heat boiler 7 and the second waste heat boiler 9 produce 1.7 MPA saturated steam 30 tons / hour in total, and the shaft power of the circulating gas compressor 14 is 194.04 Kw. The yield of methane product is 96.7%, CO and CO 2 The total content is 18ppm.

[0048] Example 2 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 55.5 5.34 0.40 10.48 4.02 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.40 0.67 2.13 0.01 0.05 The coke oven gas after desulfurization, naphthalene removal, benzene removal and tar and other impurities is pressurized to 3.5MPa by the compressor and then enters the deep desulfurization coke oven gas preheater 10 to be preheated to 280°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. Among them, it then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, and then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; wherein, the operating temperature is 450°C, the air velocity is 3000h-1, the operating pressure is 3.5MPa, and the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1ppm, and then enters the methanation process; in this method of the present invention, the coke oven gas does not need to undergo cooling and heating heat exchange in the fine desulfurization process, and directly enters the methanation process after high-temperature fine desulfurization.

[0049] The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.8) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 1.00) at a temperature of 280°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 283°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw gas that will enter the deep desulfurization process in the coke oven. The gas preheater 10 is heat exchanged to 200-220°C, and then heat exchanged with the circulating gas after the circulating gas compressor 11 and the circulating gas compressor 14 are pressurized, and finally cooled to 90-110°C by the first heat exchanger 12 and enter the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 210°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 through the inlet and outlet heat exchangers 15 to 245-260°C, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after cooling by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0050] Wherein, supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 75%) is added at the inlet of the secondary methanation reactor 8 .

[0051] The first waste heat boiler 7 and the second waste heat boiler 9 produce 1.7MPA saturated steam 29.8 tons / hour in total, and the shaft power of the circulating gas compressor 14 is 148.52Kw. The yield of methane product is 98.3%, CO and CO 2 The total content is 21ppm.

[0052] Example 3 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 54.07 5.344 0.2 11.3 4.8 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.41 0.67 2.13 0.01 0.05 After desulfurization, naphthalene removal, benzene removal and tar and other impurities, the coke oven gas is compressed to 3.1MPa by the compressor and then enters the deep desulfurization coke oven gas preheater 10 to be preheated to 250°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. Among them, it then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, and then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; the operating temperature is 380°C, and the air velocity is 1000h -1 , the operating pressure is 3.0MPa, the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1ppm, and then enters the methanation process; in the method of the present invention, the coke oven gas does not need to undergo cooling and heating heat exchange in the fine desulfurization process, and directly enters the methanation process after high-temperature fine desulfurization.

[0053] The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.7) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 1.38) at a temperature of 290°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 282°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw gas that will enter the deep desulfurization process in the coke oven. The gas preheater 10 is heat exchanged to 200-220°C, and then heat exchanged with the circulating gas after the circulating gas compressor 11 and the circulating gas compressor 14 are pressurized, and finally cooled to 80-100°C by the first heat exchanger 12 before entering the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 245°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 through the inlet and outlet heat exchangers 15 to 240-250°C, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after cooling by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0054] Wherein, supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 80%) is added at the inlet of the secondary methanation reactor 8 .

[0055] The first waste heat boiler 7 and the second waste heat boiler 9 produce 1.7 MPA saturated steam 31.2 tons / hour in total, and the shaft power of the circulating gas compressor 14 is 194.20 Kw. The yield of methane product is 98.1%, CO and CO 2 The total content is 12ppm.

[0056] Example 4 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 54.07 5.344 0.2 11.3 4.8 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.41 0.67 2.13 0.01 0.05 After desulfurization, naphthalene removal, benzene removal and tar and other impurities, the coke oven gas is compressed to 3.5MPa by the compressor and then enters the deep desulfurization coke oven gas preheater 10 to be preheated to 240°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. Among them, it then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; the operating temperature is 400°C, and the air velocity is 800h -1 , the operating pressure is 2.8 MPa, the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1 ppm, and then enters the methanation process; The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.7) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein, the gas flow ratio of the circulating gas to the coke oven gas is 1.49) at a temperature of 280°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 280°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw gas that will enter the deep desulfurization process in the coke oven gas. The preheater 10 is heat exchanged to 200-220°C, and then heat exchanged with the circulating gas after the circulating gas compressor 11 and the circulating gas compressor 14 are pressurized, and finally cooled to 90-110°C by the first heat exchanger 12 and enter the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 210-250°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 through the inlet and outlet heat exchanger 15 to 250-260°C, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after cooling by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0057] Supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 75%) is added at the inlet of the secondary methanation reactor 8 .

[0058] The first waste heat boiler 7 and the second waste heat boiler 9 produce 1.7 MPA saturated steam 30.7 tons / hour in total, and the shaft power of the circulating gas compressor 14 is 194.23 Kw. The yield of methane product is 96.9%, CO and CO 2 The total content is 23ppm.

[0059] Example 5 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 54.07 5.344 0.2 11.3 4.8 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.41 0.67 2.13 0.01 0.05 After desulfurization, naphthalene removal, benzene removal and tar and other impurities, the coke oven gas is compressed to 3.3MPa by the compressor and then enters the deep desulfurization coke oven gas preheater 10 to be preheated to 250°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. Among them, it then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; the operating temperature is 410°C, and the air velocity is 2000h -1 , the operating pressure is 3.2 MPa, the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1 ppm, and then enters the methanation process; The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.7) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 0.94) at a temperature of 280°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 286°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw gas that will enter the deep desulfurization process in the coke oven. The furnace gas preheater 10 is heat exchanged to 200-220°C, and then heat exchanged with the circulating gas after the circulating gas compressor 11 and the circulating gas compressor 14 are pressurized, and finally cooled to 40-60°C by the first heat exchanger 12 and enter the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 245°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 through the inlet and outlet heat exchanger 15 to 230-240°C, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after cooling by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0060] Supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 78%) is added at the inlet of the second cylinder of the compressor for increasing the pressure of the coke oven gas or at the inlet of the secondary methanation reactor 8 .

[0061] The first waste heat boiler 7 and the second waste heat boiler 9 produce 1.7 MPA saturated steam 31.8 tons / hour in total, and the shaft power of the circulating gas compressor 14 is 109.97 Kw. The yield of methane product is 98.2%, CO and CO 2 The total content is 6ppm.

[0062] Example 6 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 54.07 5.344 0.2 11.3 4.8 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.41 0.67 2.13 0.01 0.05 After desulfurization, naphthalene removal, benzene removal and tar and other impurities, the coke oven gas is compressed to 2.8MPa by the compressor and then enters the deep desulfurization coke oven gas preheater 10 to be preheated to 260°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. After that, it enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, and then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; the operating temperature is 360°C, and the air velocity is 1500h -1 , the operating pressure is 3.1 MPa, the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1 ppm, and then enters the methanation process; The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.5) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 2.50) at a temperature of 280°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 285°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw gas that will enter the deep desulfurization process. The coke oven gas is heated to 200-220°C in the coke oven gas preheater 40, and then heat exchanged with the circulating gas after being pressurized by the circulating gas compressor 11 and the circulating gas compressor 14, and finally cooled to 100°C by the first heat exchanger 12 before entering the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 250°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 through the inlet and outlet heat exchangers 15 to 230-240°C, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after being cooled by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0063] Supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 70%) is added at the inlet of the secondary methanation reactor 8 .

[0064] The first waste heat boiler 7 and the second waste heat boiler 9 produce 30.8 tons / hour of 1.7 MPA saturated steam, and the shaft power of the circulating gas compressor 14 is 252.1 Kw. The yield of methane product is 96.9%, CO and CO2 The total content is 23ppm.

[0065] Example 7 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 54.07 5.344 0.2 11.3 4.8 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.41 0.67 2.13 0.01 0.05 After desulfurization, naphthalene removal, benzene removal and tar and other impurities, the coke oven gas is compressed to 2.8MPa by the compressor and then enters the deep desulfurization coke oven gas preheater 10 to be preheated to 260°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. After that, it enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, and then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; wherein, the operating temperature is 380°C, and the air velocity is 2500h -1 , the operating pressure is 3.0 MPa, the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1 ppm, and then enters the methanation process; The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.9) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 1.00) at a temperature of 280°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 280°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw material that will enter the deep desulfurization process. The gas is heat exchanged to 200-220°C in the coke oven gas preheater 40, and then heat exchanged with the circulating gas after being pressurized by the circulating gas compressor 11 and the circulating gas compressor 14, and finally cooled to 100°C by the first heat exchanger 12 before entering the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 235°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 to 240°C through the inlet and outlet heat exchangers 15, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after being cooled by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0066] Supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 80%) is added at the inlet of the secondary methanation reactor 8 .

[0067] The first waste heat boiler 7 and the second waste heat boiler 9 produce 1.7 MPA saturated steam 31.8 tons / hour in total, and the shaft power of the circulating gas compressor 14 is 186.26 Kw. The yield of methane product is 97.5%, CO and CO 2 The total content is 19ppm.

[0068] Example 8 Coke oven gas composition: Components <![CDATA[H 2 ]]> <![CDATA[N 2 ]]> <![CDATA[O 2 ]]> CO <![CDATA[CO 2 ]]> Content, mol% 54.07 5.344 0.2 11.3 4.8 Components <![CDATA[CH 4 ]]> <![CDATA[C 2 H 6 ]]> <![CDATA[C 2 H 4 ]]> <![CDATA[C 3 H 8 ]]> <![CDATA[C 3 H 6 ]]> Content, mol% 21.41 0.67 2.13 0.01 0.05 After desulfurization, naphthalene removal, benzene removal and tar and other impurities, the coke oven gas is compressed to 3.3MPa by the compressor and then enters the deep desulfurization coke oven gas preheater 10 to be preheated to 240°C, and then enters the pre-hydrogenation reactor 1 and the primary hydrogenation reactor 2 in sequence to carry out hydrogenation reactions of organic sulfur and unsaturated hydrocarbons in the coke oven gas. Among them, it then enters the first solid desulfurization catalyst reactor 3 for the first removal of hydrogen sulfide, then enters the secondary hydrogenation reactor 4 for the secondary hydrogenation reaction of organic sulfur, and then continues to enter the second solid desulfurization catalyst reactor 5 for the secondary removal of hydrogen sulfide; the operating temperature is 420°C, and the air velocity is 800h -1 , the operating pressure is 2.8 MPa, the hydrogen sulfide content at the outlet of the second solid desulfurization catalyst reactor 5 is less than 0.1 ppm, and then enters the methanation process; The coke oven gas after deep purification is divided into two paths. The first path (the flow ratio of the total coke oven gas is 0.9) is mixed with the circulating gas from the outlet of the secondary methanation reactor 8 after being pressurized by the circulating gas compressor 14 (wherein the gas flow ratio of the circulating gas to the coke oven gas is 0.50) at a temperature of 280°C, and enters the primary methanation reactor 6 for reaction. The outlet gas recovers heat to 280°C through the first waste heat boiler 7, and then mixes with the second coke oven gas. After mixing, the temperature is 280°C and enters the secondary methanation reactor 8 for reaction. The outlet gas first recovers heat to 280°C through the second waste heat boiler 9, and then mixes with the coke oven gas raw material that will enter the deep desulfurization process. The gas is heat exchanged to 200-220°C in the coke oven gas preheater 40, and then heat exchanged with the circulating gas after being pressurized by the circulating gas compressor 11 and the circulating gas compressor 14, and finally cooled to 40°C by the first heat exchanger 12 and then enters the first gas-liquid separator 13; the outlet gas of the first gas-liquid separator 13 is divided into two streams, one of which is pressurized by the circulating gas compressor 14 and then heat exchanged with the outlet gas of the secondary methanation reactor 8 to 180°C, mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor 6, and the other is heat exchanged with the outlet gas of the tertiary methanation reactor 16 to 240°C through the inlet and outlet heat exchangers 15, and enters the tertiary methanation reactor 16 for reaction. In this arrangement, the outlet gas first exchanges heat with the inlet gas to recover heat, and then enters the second gas-liquid separator 18 to separate water after being cooled by the second heat exchanger 17, and then enters the ammonia washing tower 19. The ammonia washing tower 19 uses desalted water for washing to remove impurities such as trace amounts of ammonia in the gas, and then goes to the deep cold separation process.

[0069] Supplementary hydrogen-rich gas (the volume fraction of hydrogen in the hydrogen-rich gas is 75%) is added at the inlet of the secondary methanation reactor 8 .

[0070] The first waste heat boiler 7 and the second waste heat boiler 9 produce 1.7 MPA saturated steam 31.3 tons / hour in total, and the shaft power of the circulating gas compressor 14 is 77.62 Kw. The yield of methane product is 98.5%, CO and CO 2 The total content is 7ppm.

[0071] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A method for synthesizing methane from high carbon-hydrogen ratio coke oven gas, characterized in that: include: The high carbon-to-hydrogen ratio coke oven gas is treated to remove sulfur, naphthalene, benzene and tar impurities, and then hydrogenated to remove organic sulfur to obtain deeply purified coke oven gas, which is sent to the methanation process; In the methanation process, after a period of operation, the deeply purified coke oven gas is divided into two paths. The first path and the circulating gas pressurized by the circulating gas compressor (14) from the outlet of the secondary methanation reactor (8) enter the primary methanation reactor (6) for reaction. The outlet gas of the primary methanation reactor (6) recovers heat through the first waste heat boiler (7), and then is mixed with the deeply purified coke oven gas of the second path and enters the secondary methanation reactor (8) for reaction. The outlet gas of the secondary methanation reactor (8) recovers heat through the second waste heat boiler (9), and then exchanges heat with the high carbon-hydrogen ratio coke oven gas in the coke oven gas preheater (10), and then exchanges heat with the compressed gas produced by the circulating gas compressor (14) in the circulating gas heat exchanger (11). The compressed circulating gas is heat exchanged, and finally cooled by the first heat exchanger (12) before entering the first gas-liquid separator (13); the outlet gas from the first gas-liquid separator (13) is divided into two streams, one of which is pressurized by the circulating gas compressor (14) and then heat exchanged with the outlet gas of the secondary methanation reactor (8), and then mixed with the deeply purified coke oven gas and enter the primary methanation reactor (6); the other of which is heat exchanged with the outlet gas of the tertiary methanation reactor (16) in the inlet and outlet heat exchangers (15) and then enters the tertiary methanation reactor (16); the outlet gas of the tertiary methanation reactor (16) is cooled by the second heat exchanger (17) and enters the second gas-liquid separator (18) to separate water and then enters the ammonia washing tower (19).

2. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 1, characterized in that: The process of obtaining deeply purified coke oven gas is as follows: the coke oven gas from which sulfur, naphthalene, benzene and tar impurities have been removed is pressurized and then enters a coke oven gas preheater (10) for preheating, then enters a pre-hydrogenation reactor (1) and a primary hydrogenation reactor (2) in sequence for primary hydrogenation reaction of organic sulfur and unsaturated hydrocarbons in the coke oven gas, then enters a first solid desulfurization catalyst reactor (3) for primary removal of hydrogen sulfide, then enters a secondary hydrogenation reactor (4) for secondary hydrogenation reaction of organic sulfur, and then continues to enter a second solid desulfurization catalyst reactor (5) for secondary removal of hydrogen sulfide.

3. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 1, characterized in that: The deeply purified coke oven gas is divided into two paths, the first path accounts for 0.5~0.9 of the flow rate of the total coke oven gas; the gas flow rate ratio of the circulating gas to the coke oven gas is 0.50~2.

50.

4. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 1, characterized in that: The first gas is mixed with the circulating gas from the outlet of the secondary methanation reactor (8) after being pressurized by the circulating gas compressor (14) and the temperature is 280-320°C. The gas enters the primary methanation reactor (6) for reaction. The outlet gas recovers heat to 240-280°C by the first waste heat boiler (7) and is then mixed with the second coke oven gas. The mixed gas has a temperature of 280-320°C and enters the secondary methanation reactor (8) for reaction. The outlet gas first recovers heat to 260-280°C by the second waste heat boiler (9) and is then heat exchanged with the pressurized coke oven gas raw gas to be entered into the deep desulfurization process in the coke oven gas preheater (10) to 200-220°C. The gas is then heat exchanged with the circulating gas pressurized by the circulating gas compressor (14) in the circulating gas heat exchanger (11). The gas is finally cooled to 40-110°C by the first heat exchanger (12) and enters the first gas-liquid separator (13).

5. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 4, characterized in that: The outlet gas from the first gas-liquid separator (13) is divided into two streams. One stream is pressurized by the circulating gas compressor (14) and then heat exchanged with the outlet gas of the secondary methanation reactor (8) to a temperature of 180-250° C., mixed with the deeply purified coke oven gas and then sent to the inlet of the primary methanation reactor (6). The other stream is heat exchanged with the outlet gas of the tertiary methanation reactor (16) to a temperature of 230-280° C. through the inlet and outlet heat exchangers (15) and then enters the tertiary methanation reactor (16) for reaction.

6. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 2, characterized in that: The coke oven gas from which sulfur, naphthalene, benzene and tar impurities have been removed is pressurized to 2.8-3.5 MPa and then enters the coke oven gas preheater (10) to be preheated to 240-280°C.

7. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 2, characterized in that: The H2S content in deeply purified coke oven gas is less than 0.1ppm.

8. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 2, characterized in that: The operating temperature of the first solid desulfurization catalyst reactor (3) and the second solid desulfurization catalyst reactor (5) is 320°C to 450°C, and the air velocity is 500 to 3000 h -1 , the operating pressure is 2.8~3.5MPa.

9. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 1, characterized in that: Supplementary hydrogen-rich gas is added at the inlet of the second cylinder of the compressor for increasing the pressure of the coke oven gas or at the inlet of the secondary methanation reactor (8).

10. The method for synthesizing methane from high carbon-hydrogen ratio coke oven gas according to claim 1, characterized in that: The components of the raw gas of high carbon-hydrogen ratio coke oven gas include, by mole percentage, 48.7%~57.5% H2, 20.1%~24.6% CH4, 3.5%~8.3% N2, 0.55%~0.83% C2H6, 0.20%~0.85% O2, 1.95%~2.75% C2H4, 9.7%~11.3% CO, 0~0.12% C3H8, 3.3%~4.8% CO2 and 0~0.7% C3H6.

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