Coke oven gas methanation system and process

Abstract

The invention belongs to the field of chemical environmental protection, and relates to a coke oven gas methanation system and process. The system comprises a first-stage methanation module and a second-stage methanation module which are sequentially arranged in the airflow direction; the primary methanation module comprises a gas supply main pipe for conveying coke oven gas subjected to fine desulfurization and at least one gas supply branch pipe formed by branches of the gas supply main pipe, and an isothermal bed reactor and a heat exchanger are arranged on each gas supply branch pipe in a complete set; the secondary methanation module comprises two sets of adiabatic bed reactors and heat exchangers which are arranged in a sleeving manner; and an outlet of each gas supply branch pipe is converged with the gas supply main pipe and then is communicated to the secondary methanation module. One end of the second bypass branch pipe is communicated to a pipeline in front of a branch of the air supply main pipe, and the other end of the second bypass branch pipe is communicated to an outlet of the third heat exchanger. The temperature of the reactor is effectively controlled on the premise that a large amount of circulating gas is not needed, and the investment cost and the operation energy consumption are reduced while the production requirement is met.

Description

Technical Field

[0001] The invention belongs to the field of chemical environmental protection and relates to a coke oven gas methanation system and process. Background Art

[0002] Coke oven gas is a byproduct of the coal coking process and a multi-purpose gas source. It is a raw gas generated by the cracking of organic matter after high-temperature dry distillation of coal. The raw gas from the coke oven is sent out of the boundary area as coke oven gas after the initial purification process such as condensation and blasting, desulfurization, ammonia washing, and benzene washing to recover byproducts such as tar, sulfur, ammonia, and benzene. The coke oven gas after preliminary purification is rich in H with a volume fraction of 55% to 60%. 2 , 23% to 27% CH 4 , 5% to 8% CO, 1.5% to 3% CO 2 3%~5%N 2 , 0.3% to 0.5% O 2 2% to 3% C n H m It also contains a large amount of impurities such as tar, benzene, naphthalene, ammonia, hydrogen cyanide, organic sulfur and inorganic sulfur, etc. Its calorific value is about 17-19 MJ / m 3 .

[0003] From the composition of coke oven gas, we can see that coke oven gas has high calorific value and contains H 2 High, containing CH 4 High, rich in a certain amount of CO and CO 2 A large amount of coke oven gas is directly burned and discharged into the atmosphere, which not only causes a huge waste of high-value energy, but also brings serious environmental pollution risks. Therefore, how to reasonably, economically, efficiently and cleanly utilize such a huge amount of coke oven gas is a very important issue.

[0004] At present, the rich hydrogen resources in coke oven gas are used to react with CO and CO 2 The reaction generates CH 4 , improve CH 4 The methanation process of producing synthetic natural gas and extracting hydrogen as a by-product is one of the main ways to clean and efficiently utilize coke oven gas. The methanation process mainly involves the following reactions:

[0005] (1) ΔH 298 =-206KJ / mol

[0006] (2) ΔH 298 =-165KJ / mol

[0007] It can be seen that the above reaction process is a highly exothermic reaction, which will bring about a huge temperature rise (for every 1% increase in CO content, the temperature rises by 72°C; CO 2 For every 1% increase in content, the temperature rises by 60°C). Too high a reaction temperature not only affects the chemical equilibrium of the positive reaction and aggravates the side reaction, but also brings huge hidden dangers to safe production.

[0008] To address this problem, the current methanation process mainly uses a circulating adiabatic fixed bed process, that is, the product of the first reactor or the second reactor is returned to the inlet of the first reactor to dilute the carbon content of the inlet gas. The circulating adiabatic fixed bed process has the advantages of simple operation and easy temperature control, but it also has defects such as low reaction rate, bulky equipment, and difficult heat removal. In order to remove the heat of reaction, it is usually necessary to recycle a large amount of gas to control the reactor temperature, which increases the complexity of the process. In addition, a large amount of circulating gas must be equipped with a corresponding circulating compressor, which is bound to greatly increase the one-time investment and operating energy consumption of the equipment. Summary of the invention

[0009] In view of this, the object of the present invention is to provide a coke oven gas methanation system and process, which can effectively control the temperature of the reactor without requiring a large amount of circulating gas, thereby meeting production requirements while reducing investment costs and operating energy consumption.

[0010] To achieve the above-mentioned purpose, in a first aspect, the present invention provides the following coke oven gas methanation system, comprising a primary methanation module and a secondary methanation module arranged in sequence along the gas flow direction; the primary methanation module comprises a gas supply main pipe for conveying the coke oven gas after fine desulfurization, and at least one gas supply branch formed by branches of the gas supply main pipe, each gas supply branch pipe is provided with an isothermal bed reactor and a heat exchanger in a set; the secondary methanation module comprises two sets of adiabatic bed reactors and heat exchangers in a set configuration; wherein, the outlet of each gas supply branch pipe is connected to the secondary methanation module after merging with the gas supply main pipe.

[0011] Optionally, the primary methanation module includes a first gas supply branch and a second gas supply branch arranged in parallel with the gas supply main, the first gas supply branch is provided with a first isothermal bed reactor and a first heat exchanger, and the second gas supply branch is provided with a second isothermal bed reactor and a second heat exchanger.

[0012] Optionally, the secondary methanation module includes a first adiabatic bed reactor and a third heat exchanger and a second adiabatic bed reactor and a fourth heat exchanger configured as a set.

[0013] Optionally, the methanation system further includes a first bypass branch pipe, one end of which is connected to the pipeline where the gas supply main pipe and the gas supply branch pipe merge, and the other end of which is connected to the outlet of the third heat exchanger.

[0014] Optionally, the methanation system further includes a second bypass branch pipe, one end of which is connected to the pipeline before the gas supply main pipe branches, and the other end of which is connected to the outlet of the third heat exchanger.

[0015] Optionally, the methanation system further includes a tertiary methanation module disposed after the secondary methanation module, and the tertiary methanation module includes a reactor and a fifth heat exchanger.

[0016] Optionally, the first bypass branch pipe is provided with a valve for controlling its on-off, and the second bypass branch pipe is provided with a valve for controlling its on-off and a flow valve for controlling its flow.

[0017] Optionally, flow valves are provided on the gas supply main pipe and each gas supply branch pipe.

[0018] Optionally, the isothermal bed reactor on the gas supply branch has a processing rate not exceeding 10000 Nm 3 / h.

[0019] In a second aspect, the present invention provides a coke oven gas methanation process, which is applied to the aforementioned coke oven gas methanation system. The coke oven gas methanation process comprises: when the temperature rise of the first adiabatic bed reactor is large, opening the second bypass branch pipe to reduce the processing capacity of the primary methanation module, thereby reducing the temperature rise of the coke oven gas after being processed by the primary methanation module, and finally reducing the processing load of the first adiabatic bed reactor.

[0020] When the amount of coke oven gas to be processed is less than 50000Nm 3 / h, the first gas supply branch pipe and the second gas supply branch pipe are opened; the coke oven gas is divided into three routes, entering the first isothermal bed reactor, the second isothermal bed reactor and the gas supply main pipe respectively; the outlet streams of the first isothermal bed reactor and the second isothermal bed reactor are cooled by the corresponding heat exchangers, mixed with the coke oven gas in the gas supply main pipe, and enter the first adiabatic bed reactor together;

[0021] When the amount of coke oven gas to be treated is greater than or equal to 50000Nm 3 / h, the first gas supply branch pipe, the second gas supply branch pipe and the second bypass branch pipe are opened; the coke oven gas is divided into four routes, which respectively enter the first isothermal bed reactor, the second isothermal bed reactor, the gas supply main pipe and the second adiabatic bed reactor; the outlet flows of the first isothermal bed reactor and the second isothermal bed reactor are cooled by the corresponding heat exchangers, mixed with the coke oven gas in the gas supply main pipe, and enter the first adiabatic bed reactor together.

[0022] When the amount of coke oven gas to be processed is 30000Nm 3 / h, the gas volume ratio of the first gas supply branch, the second gas supply branch and the gas supply main is 1:1:2, and the temperatures of the first isothermal bed reactor, the second isothermal bed reactor and the first adiabatic bed reactor are set to 450°C, 450°C, and 530-550°C, respectively.

[0023] When the amount of coke oven gas to be processed is 50000Nm 3 / h, the gas volume ratio of the first gas supply branch, the second gas supply branch, the gas main and the second bypass branch is 1:1:2:1, and the temperatures of the first isothermal bed reactor, the second isothermal bed reactor, the first adiabatic bed reactor and the second adiabatic bed reactor are set to 480°C, 480°C, 550°C and 530°C, respectively.

[0024] When the amount of coke oven gas to be processed is 60000Nm 3 / h, the gas volume ratio of the first gas supply branch, the second gas supply branch, the gas main and the second bypass branch is 1:1:2:2, and the temperatures of the first isothermal bed reactor, the second isothermal bed reactor, the first adiabatic bed reactor and the second adiabatic bed reactor are set to 480°C, 480°C, 550°C and 580°C, respectively.

[0025] The beneficial effects of the present invention are:

[0026] First, in the traditional methanation process using an adiabatic fixed bed, in order to control the temperature of the reactor, it is often necessary to recirculate a large amount of gas, which not only increases the operating energy consumption, but also significantly increases the equipment investment cost. The coke oven gas methanation system provided by the present invention achieves effective removal of reaction heat by coupling an isothermal bed reactor with an adiabatic bed reactor and setting up multiple heat exchangers, without requiring a large amount of circulating gas to re-enter the reactor inlet, thereby saving energy consumption and investment, and successfully avoiding the defect of the traditional adiabatic fixed bed process requiring large amount of gas circulation.

[0027] Secondly, the present invention achieves effective control of the temperature rise of the methanation process without the need for large-volume circulation by optimizing the pipeline structure and equipment configuration. Specifically, the present invention sets a gas supply main and multiple gas supply branches, and sets an isothermal bed reactor and a heat exchanger on the gas supply branch. The coke oven gas is introduced into each gas supply branch for a primary methanation reaction. This diversion design helps to reduce the processing load and temperature rise pressure of a single reactor. Then, each gas supply branch and the gas supply main pipe are combined and enter the secondary methanation module together, which reduces the content of carbon monoxide and carbon dioxide at the reactor inlet and helps to control the temperature rise inside it. Furthermore, the present invention is provided with a second bypass branch. When the temperature rise of the first adiabatic bed reactor of the secondary methanation module is large, the coke oven gas in the second bypass branch is mixed with the outlet material of the first adiabatic bed reactor and enters the second adiabatic bed reactor together to reduce the processing load of the first adiabatic bed reactor, thereby controlling its temperature rise and ensuring the stable progress of the reaction.

[0028] In addition, since large-volume circulation is avoided, the size of each reactor in the methanation system of the present invention can be reduced accordingly, the equipment layout can be more compact, and the floor space is reduced accordingly. This not only reduces the construction cost, but also facilitates the flexible adjustment and optimization of the process. The present invention flexibly adjusts the reaction load of each reactor through various regulating valves, pipelines, etc., and realizes the function of online material replacement. This means that when replacing the deactivated catalyst, there is no need to interrupt the entire production process, thereby ensuring the continuity and stability of production. Finally, the present invention sets a heat exchanger after the isothermal bed reactor and the adiabatic bed reactor, which can not only effectively cool down the outlet logistics, but also produce steam as a by-product, thereby improving the utilization efficiency of energy and contributing to energy conservation and emission reduction.

[0029] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 This is a structural schematic diagram of the coke oven gas methanation system provided by the present invention.

[0032] Reference numerals:

[0033] 1-first isothermal bed reactor; 2-second isothermal bed reactor; 3-first heat exchanger; 4-second heat exchanger; 5-first adiabatic bed reactor; 6-third heat exchanger; 7-second adiabatic bed reactor; 8-fourth heat exchanger; 9-reactor; 10-fifth heat exchanger; 11-gas supply main; 12-first gas supply branch; 13-second gas supply branch; 14-first bypass branch; 15-second bypass branch; 16-first methanation module; 17-second methanation module; 18-third methanation module. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0035] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0036] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] Coke oven gas has high calorific value and contains H 2 High, containing CH 4 High, rich in a certain amount of CO and CO 2 And other characteristics.

[0038] At present, methanation of coke oven gas is one of the main ways to clean and efficiently utilize coke oven gas. Specifically, the rich hydrogen resources in coke oven gas are used to react with CO and CO2 The reaction generates CH 4 , improve CH 4 The content of methanogens is used to produce synthetic natural gas and extract hydrogen as a byproduct. However, the chemical reaction involved in the methanogenization process is a highly exothermic reaction, and the reaction process will cause a huge temperature rise. Excessively high reaction temperature not only affects the chemical equilibrium of the positive reaction and aggravates the side reaction, but also brings huge hidden dangers to safe production.

[0039] To address this problem, the current methanation process mainly uses a circulating adiabatic fixed bed process. In order to remove the reaction heat and control the temperature of the reactor, it is often necessary to recirculate a large amount of gas, which not only increases the operating energy consumption, but also significantly increases the equipment investment cost. The isothermal bed reactor is equipped with a heat exchanger, which can remove the reaction heat through a cooling device to maintain the thermal stability of the system. The isothermal bed reactor can reasonably control the flow rate of the cooling medium according to the difference in catalysts, so that the catalyst activity reaches the optimal reaction temperature, and it does not require a large amount of circulating gas to re-enter the reactor inlet. However, the internal structure of the isothermal bed reactor is complex and the processing is difficult, and the large-scale industrial application of the isothermal bed reactor still has bottlenecks.

[0040] Based on this, the present invention proposes a coke oven gas methanation system, which realizes efficient and clean utilization of coke oven gas by coupling an isothermal bed reactor with an adiabatic bed reactor and optimizing the system pipeline configuration, which not only avoids the large gas volume circulation problem in the traditional process, but also saves equipment investment and operating costs. At the same time, the flexibility of the process and energy utilization efficiency are further improved by measures such as flexible adjustment of reaction load, online material replacement and by-product steam.

[0041] See also Figure 1 The present invention provides a coke oven gas methanation system, comprising a primary methanation module 16, a secondary methanation module 17 and a tertiary methanation module 18 arranged in sequence along the airflow direction. The primary methanation module 16, the secondary methanation module 17 and the tertiary methanation module 18 adopt a strategy of split flow reaction and coordinated temperature control for the coke oven gas to achieve step temperature control in the methanation process, avoid excessive temperature rise of a single reactor, and improve production efficiency.

[0042] Specifically, the primary methanation module 16 includes a gas supply main 11 for conveying finely desulfurized coke oven gas, and at least one gas supply branch formed by branching the gas supply main 11, and each gas supply branch is provided with an isothermal bed reactor and a heat exchanger. Preferably, the primary methanation module 16 includes a first gas supply branch 12 and a second gas supply branch 13 arranged in parallel with the gas supply main 11, the first gas supply branch 12 is provided with a first isothermal bed reactor 1 and a first heat exchanger 3, and the second gas supply branch 13 is provided with a second isothermal bed reactor 2 and a second heat exchanger 4. Furthermore, the outlets of the first gas supply branch pipe 12 and the second gas supply branch pipe 13 are both connected to the secondary methanation module 17 after merging with the gas supply main pipe 11, and the coke oven gas undergoes primary methanation treatment and primary cooling in the first gas supply branch pipe 12 and the second gas supply branch pipe 13 respectively, and then is mixed with the coke oven gas in the gas supply main pipe 11, and then is sent into the secondary methanation module 17 together.

[0043] The secondary methanation module 17 includes two sets of adiabatic bed reactors and heat exchangers configured as a set; preferably, the secondary methanation module 17 includes a first adiabatic bed reactor 5 and a third heat exchanger 6 and a second adiabatic bed reactor 7 and a fourth heat exchanger 8 configured as a set.

[0044] In some optional embodiments, the methanation system further includes a first bypass branch 14, one end of which is connected to the pipeline after the gas supply main pipe 11 and the gas supply branch pipe merge, and the other end is connected to the outlet of the third heat exchanger 6. A valve for controlling its on and off is provided on the first bypass branch 14. It can be understood that the first adiabatic bed reactor 5 and the second adiabatic bed reactor 7 can be used as backup for each other. When the methanation catalyst in the first adiabatic bed reactor 5 is deactivated, the pipeline connecting the gas supply main pipe and the first adiabatic bed reactor 5 is immediately cut off, and the first bypass branch 14 is opened at the same time, and the gas supply main pipe is connected to the inlet of the second adiabatic bed reactor 7. At this time, the first adiabatic bed reactor 5 has been cut out of the system, and the catalyst in the first adiabatic bed reactor 5 can be replaced. After the catalyst is replaced, the first bypass branch 14 is closed, and the gas supply main pipe is restored to the first adiabatic bed reactor 5. By setting the first bypass branch 14, it can be ensured that the first adiabatic bed reactor 5 can be continuously produced without affecting the material replacement.

[0045] In some optional embodiments, the methanation system further includes a second bypass branch 15, one end of which is connected to the pipeline before the gas supply main 11 branches, and the other end is connected to the outlet of the third heat exchanger 6. The second bypass branch 15 is provided with a valve for controlling its on-off and a flow valve for controlling its flow. It can be understood that the second bypass branch 15 is led out from the gas supply main and directly connected to the second adiabatic bed reactor 7 across the primary methanation module 16. When the temperature rise of the first adiabatic bed reactor 5 is large, opening the second bypass branch 15 can reduce the processing capacity of the primary methanation module 16, directly reduce the temperature rise of the coke oven gas after the primary methanation post-treatment, thereby reducing the processing load of the first adiabatic bed reactor 5, and achieving the purpose of controlling the temperature rise. Alternatively, when the amount of coke oven gas to be processed introduced into the gas supply main 11 is large, the second bypass branch 15 can be directly opened, and the coke oven gas is divided into four paths, which respectively enter the first gas supply branch 12, the second gas supply branch 13, the gas supply main 11 and the second adiabatic bed reactor 7 to disperse the processing load of the first adiabatic bed reactor 5.

[0046] The tertiary methanation module 18 includes a reactor 9 and a fifth heat exchanger 10. The reactor 9 is used to react the remaining CO and CO in the coke oven gas. 2 The fifth heat exchanger 10 is used to perform the final cooling process on the coke oven gas so that the temperature of the final product and the carbon-containing gas content meet the standards for entering the next process.

[0047] In some optional embodiments, flow valves are provided on the gas supply main pipe 11 and each gas supply branch pipe to control the flow ratio of each route of blast furnace gas. The processing rate of the isothermal bed reactor on the gas supply branch pipe does not exceed 10000Nm 3 / h.

[0048] The present invention also provides a coke oven gas methanation process, which is applied to the above-mentioned coke oven gas methanation system. Specifically, when the temperature rise of the first adiabatic bed reactor 5 is large, the second bypass branch pipe 5 is opened to reduce the processing capacity of the primary methanation module 16, thereby reducing the temperature rise of the coke oven gas after being processed by the primary methanation module 16, and finally reducing the processing load of the first adiabatic bed reactor 5.

[0049] When the amount of coke oven gas to be processed is less than 50000Nm 3 / h, the first gas supply branch pipe 12 and the second gas supply branch pipe 13 are opened; the coke oven gas is divided into three paths, entering the first isothermal bed reactor 1, the second isothermal bed reactor 2 and the gas supply main pipe 11 respectively; the outlet streams of the first isothermal bed reactor 1 and the second isothermal bed reactor 2 are cooled by the corresponding heat exchangers, mixed with the coke oven gas in the gas supply main pipe 11, and enter the first adiabatic bed reactor 5 together;

[0050] When the amount of coke oven gas to be treated is greater than or equal to 50000Nm 3 / h, the first gas supply branch pipe 12, the second gas supply branch pipe 13 and the second bypass branch pipe 15 are opened; the coke oven gas is divided into four routes, which respectively enter the first isothermal bed reactor 1, the second isothermal bed reactor 2, the gas supply main pipe 15 and the second adiabatic bed reactor 7; the outlet logistics of the first isothermal bed reactor 1 and the second isothermal bed reactor 2 are cooled by the corresponding heat exchangers, mixed with the coke oven gas in the gas supply main pipe 11, and enter the first adiabatic bed reactor 5 together.

[0051] More specifically, when the amount of coke oven gas to be processed is 30000 Nm 3 / h, the gas volume ratio of the first gas supply branch pipe 12, the second gas supply branch pipe 13 and the gas supply main pipe 15 is 1:1:2, and the temperatures of the first isothermal bed reactor 1, the second isothermal bed reactor 2 and the first adiabatic bed reactor 5 are set to 450°C, 450°C, 530-550°C, respectively.

[0052] When the amount of coke oven gas to be processed is 50000Nm 3 / h, the gas volume ratio of the first gas supply branch 12, the second gas supply branch 13, the gas supply main 15 and the second bypass branch 15 is 1:1:2:1, and the temperatures of the first isothermal bed reactor 1, the second isothermal bed reactor 2, the first adiabatic bed reactor 5 and the second adiabatic bed reactor 7 are set to 480°C, 480°C, 550°C and 530°C, respectively.

[0053] When the amount of coke oven gas to be processed is 60000Nm 3 / h, the gas volume ratio of the first gas supply branch pipe 12, the second gas supply branch pipe 13, the gas supply main pipe 15 and the second bypass branch pipe 15 is 1:1:2:2, and the temperatures of the first isothermal bed reactor 1, the second isothermal bed reactor 2, the first adiabatic bed reactor 5 and the second adiabatic bed reactor 7 are set to 480°C, 480°C, 550°C and 580°C, respectively.

[0054] Based on the above coke oven gas methanation system and methanation process, the present invention provides the following embodiments:

[0055] Example 1

[0056] The amount of coke oven gas to be processed is 30000Nm 3 / h, that is, the amount of coke oven gas introduced into the gas supply main 11 is 30000Nm 3 / h.

[0057] Specifically, the gas supply main pipe 11 branches to form two gas supply branches, namely the first gas supply branch pipe 12 and the second gas supply branch pipe 13. The coke oven gas (temperature 250-300°C) after fine desulfurization is divided into three routes, respectively entering the first isothermal bed reactor 1 (reactor temperature of about 450°C), the second isothermal bed reactor 2 (reactor temperature of about 450°C) and the gas supply main pipe 11, with a gas volume ratio of 1:1:2. The outlet flow of the first isothermal bed reactor 1 and the second isothermal bed reactor 2 is cooled to 300°C by the first heat exchanger 3 and the second heat exchanger 4, and then mixed with the coke oven gas in the gas supply main pipe 11, and enters the first adiabatic bed reactor 5 (reactor temperature 530°C-550°C).

[0058] The outlet flow of the first adiabatic bed reactor 5 is cooled to 300-350°C by the third heat exchanger 6, and then enters the second adiabatic bed reactor 7 (reactor temperature 500-520°C). The outlet flow of the second adiabatic bed reactor 7 is cooled to 230°C by the fourth heat exchanger 8 and then enters the reactor 9. The outlet flow of the reactor 9 is cooled to 40°C by the fifth heat exchanger 10 to complete the methanation treatment and enter the subsequent process section.

[0059] Example 2

[0060] The amount of coke oven gas to be processed is 50000Nm 3 / h, that is, the amount of coke oven gas introduced into the gas supply main 11 is 50000Nm 3 / h.

[0061] Specifically, the gas supply main 11 is branched to form two gas supply branches, namely the first gas supply branch 12 and the second gas supply branch 13, and the second bypass branch 15 is opened. The coke oven gas (temperature 250-300°C) after fine desulfurization is divided into four routes, respectively entering the first isothermal bed reactor 1 (reactor temperature of about 480°C), the second isothermal bed reactor 2 (reactor temperature of about 480°C), the gas supply main 11 and the second adiabatic bed reactor 7 (reactor temperature of 530°C), with a gas volume ratio of 1:1:2:1. The outlet flow of the first isothermal bed reactor 1 and the second isothermal bed reactor 2 is cooled to 300°C by the first heat exchanger 3 and the second heat exchanger 4, and then mixed with the coke oven gas in the gas supply main 11, and enters the first adiabatic bed reactor 5 (reactor temperature of 550°C) together.

[0062] The outlet flow of the first adiabatic bed reactor 5 is cooled to 300-350°C by the third heat exchanger 6, and then mixed with the coke oven gas of the second bypass branch 15 and enters the second adiabatic bed reactor 7 together. The outlet flow of the second adiabatic bed reactor 7 is cooled to 220°C by the fourth heat exchanger 8 and enters the reactor 9. The outlet flow of the reactor 9 is cooled to 40°C by the fifth heat exchanger 10 to complete the methanation treatment and enter the subsequent process section.

[0063] Example 3

[0064] The amount of coke oven gas to be processed is 60000Nm 3 / h, that is, the amount of coke oven gas introduced into the gas supply main 11 is 60000Nm 3 / h.

[0065] Specifically, the gas supply main 11 is branched to form two gas supply branches, namely the first gas supply branch 12 and the second gas supply branch 13, and the second bypass branch 15 is opened. The coke oven gas (temperature 270°C) after fine desulfurization is divided into four routes, respectively entering the first isothermal bed reactor 1 (reactor temperature of about 480°C), the second isothermal bed reactor 2 (reactor temperature of about 480°C), the gas supply main 11 and the second adiabatic bed reactor 7 (reactor temperature of 580°C), with a gas volume ratio of 1:1:2:2. The outlet logistics of the first isothermal bed reactor 1 and the second isothermal bed reactor 2 are cooled to 290°C by the first heat exchanger 3 and the second heat exchanger 4, and then mixed with the coke oven gas in the gas supply main 11, and enter the first adiabatic bed reactor 5 (reactor temperature of 550°C) together.

[0066] The outlet flow of the first adiabatic bed reactor 5 is cooled to 280°C by the third heat exchanger 6, and then mixed with the coke oven gas of the second bypass branch 15 and enters the second adiabatic bed reactor 7 together. The outlet flow of the second adiabatic bed reactor 7 is cooled to 230°C by the fourth heat exchanger 8 and enters the reactor 9. The outlet flow of the reactor 9 is cooled to 40°C by the fifth heat exchanger 10 to complete the methanation treatment and enter the subsequent process section.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A coke oven gas methanation system, characterized in that: It comprises a primary methanation module (16) and a secondary methanation module (17) which are arranged in sequence along the airflow direction; The primary methanation module (16) comprises a gas supply main pipe (11) for conveying finely desulfurized coke oven gas, and at least one gas supply branch pipe formed by branching the gas supply main pipe (11), each of the gas supply branches being provided with an isothermal bed reactor and a heat exchanger as a set; wherein the isothermal bed reactor comprises a first isothermal bed reactor (1) and a second isothermal bed reactor (2), and the heat exchanger comprises a first heat exchanger (3) and a second heat exchanger (4); The secondary methanation module (17) comprises two sets of adiabatic bed reactors and heat exchangers configured in an integrated manner; wherein the adiabatic bed reactor comprises a first adiabatic bed reactor (5) and a second adiabatic bed reactor (7), and the heat exchanger comprises a third heat exchanger (6) and a fourth heat exchanger (8); The outlet of each gas supply branch pipe is connected to the gas supply main pipe (11) and then connected to the secondary methanation module (17).

2. The coke oven gas methanation system according to claim 1, characterized in that: The primary methanation module (16) comprises a first gas supply branch pipe (12) and a second gas supply branch pipe (13) which are arranged in parallel with the gas supply main pipe (11); a first isothermal bed reactor (1) and a first heat exchanger (3) are arranged on the first gas supply branch pipe (12); and a second isothermal bed reactor (2) and a second heat exchanger (4) are arranged on the second gas supply branch pipe (13).

3. The coke oven gas methanation system according to claim 1, characterized in that: The secondary methanation module (17) comprises a first adiabatic bed reactor (5) and a third heat exchanger (6) as well as a second adiabatic bed reactor (7) and a fourth heat exchanger (8) configured in a complete set.

4. The coke oven gas methanation system according to claim 3, characterized in that: The methanation system further comprises a first bypass branch pipe (14), one end of which is connected to the pipeline where the gas supply main pipe (11) and the gas supply branch pipe merge, and the other end of which is connected to the outlet of the third heat exchanger (6).

5. The coke oven gas methanation system according to claim 3 or 4, characterized in that: The methanation system further comprises a second bypass branch pipe (15), one end of which is connected to the pipeline before the branch of the gas supply main pipe (11), and the other end of which is connected to the outlet of the third heat exchanger (6).

6. The coke oven gas methanation system according to claim 1, characterized in that: The methanation system further comprises a tertiary methanation module (18) arranged after the secondary methanation module (17), wherein the tertiary methanation module (18) comprises a reactor (9) and a fifth heat exchanger (10).

7. The coke oven gas methanation system according to claim 4, characterized in that: The first bypass branch pipe (14) is provided with a valve for controlling its on and off.

8. The coke oven gas methanation system according to claim 5, characterized in that: The second bypass branch pipe (15) is provided with a valve for controlling its on and off and a flow valve for controlling its flow; the gas supply main pipe (11) and each of the gas supply branch pipes are provided with a flow valve.

9. A coke oven gas methanation process, applied to the coke oven gas methanation system according to any of the preceding claims, characterized in that: When the temperature rise of the first adiabatic bed reactor (5) is large, the second bypass branch pipe (5) is opened to reduce the processing capacity of the primary methanation module (16), thereby reducing the temperature rise of the coke oven gas after being processed by the primary methanation module (16), and ultimately reducing the processing load of the first adiabatic bed reactor (5).

10. The coke oven gas methanation process according to claim 9, characterized in that: When the amount of coke oven gas to be processed is less than 50000Nm 3 / h, the first gas supply branch pipe (12) and the second gas supply branch pipe (13) are opened; the coke oven gas is divided into three paths, which respectively enter the first isothermal bed reactor (1), the second isothermal bed reactor (2) and the gas supply main pipe (11); The outlet streams of the first isothermal bed reactor (1) and the second isothermal bed reactor (2) are cooled in corresponding heat exchangers and then mixed with the coke oven gas in the gas supply main pipe (11) and enter the first adiabatic bed reactor (5) together; When the amount of coke oven gas to be treated is greater than or equal to 50000Nm 3 / h, the first gas supply branch pipe (12), the second gas supply branch pipe (13) and the second bypass branch pipe (15) are opened; the coke oven gas is divided into four paths, which respectively enter the first isothermal bed reactor (1), the second isothermal bed reactor (2), the gas supply main pipe (15) and the second adiabatic bed reactor (7); The outlet flows of the first isothermal bed reactor (1) and the second isothermal bed reactor (2) are cooled by corresponding heat exchangers and then mixed with the coke oven gas in the gas supply main (11) and enter the first adiabatic bed reactor (5) together.

11. The coke oven gas methanation process according to claim 10, characterized in that: When the amount of coke oven gas to be processed is 30000Nm 3 / h, the gas volume ratio of the first gas supply branch pipe (12), the second gas supply branch pipe (13) and the gas supply main pipe (15) is 1:1:2, and the temperatures of the first isothermal bed reactor (1), the second isothermal bed reactor (2) and the first adiabatic bed reactor (5) are set to 450°C, 450°C, and 530-550°C, respectively.

12. The coke oven gas methanation process according to claim 10, characterized in that: When the amount of coke oven gas to be processed is 50000Nm 3 / h, the gas volume ratio of the first gas supply branch pipe (12), the second gas supply branch pipe (13), the gas supply main pipe (15) and the second bypass branch pipe (15) is 1:1:2:1, and the temperatures of the first isothermal bed reactor (1), the second isothermal bed reactor (2), the first adiabatic bed reactor (5) and the second adiabatic bed reactor (7) are set to 480°C, 480°C, 550°C and 530°C, respectively.

13. The coke oven gas methanation process according to claim 10, characterized in that: When the amount of coke oven gas to be processed is 60000Nm 3 / h, the gas volume ratio of the first gas supply branch pipe (12), the second gas supply branch pipe (13), the gas supply main pipe (15) and the second bypass branch pipe (15) is 1:1:2:2, and the temperatures of the first isothermal bed reactor (1), the second isothermal bed reactor (2), the first adiabatic bed reactor (5) and the second adiabatic bed reactor (7) are set to 480°C, 480°C, 550°C and 580°C, respectively.

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