Process for the co-production of methanol and natural gas and apparatus therefor

Abstract

The present application relates to the field of petroleum chemical industry, in particular to a method and device for co-production of methanol and natural gas. The method comprises: (1) methanolization of raw gas to obtain methanol and other streams; (2) methanation of the other streams to obtain natural gas; wherein the raw gas comprises coke oven gas and a carbon supplement. The present application first performs methanolization and then methanation after supplementing carbon to the coke oven gas, realizes co-production of methanol and methane, and significantly improves the single-pass selectivity of methane (methane concentration in natural gas).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of petroleum chemical industry, in particular to a method and device for co-production of methanol and natural gas. BACKGROUND

[0002] With the rapid development of modern chemical industry, energy and environment have become a global concern. Methanol, as an important chemical raw material, vehicle fuel and clean energy carrier, plays an irreplaceable role in the field of energy and chemical industry.

[0003] At the same time, the contradiction between the energy structure of "rich coal, poor oil, and little gas" and clean and environmental protection is also increasing. In addition, about 150 billion Nm 3 Coke oven gas, in addition to self-use, domestic and commercial fuel, power generation, a considerable part is directly discharged, wasting resources and polluting the environment; at the same time, comprehensive utilization of CO2 is also the future trend. The use of coke oven gas to supplement CO2 to prepare synthetic natural gas not only can produce high-grade clean natural gas resources, but also can be used for co-production of methanol, realizing the flexible adjustment of natural gas and methanol production, which has great social, environmental and economic benefits.

[0004] However, the current process for co-production of methanol and natural gas has long process, high energy consumption, large investment, high reaction pressure and high reaction temperature, high safety requirements for equipment, high production risk, and low CH4 content in natural gas product, which does not meet the requirements of natural gas pipeline transportation (CH4 content greater than 96%). SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned problems existing in the prior art, and to provide a method and device for co-production of methanol and natural gas, which has the characteristics of short process, low energy consumption, small investment, low reaction temperature, and high methane concentration in the obtained natural gas.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a method for co-production of methanol and natural gas, which comprises:

[0007] (1) methanolization of raw gas to obtain methanol and other streams;

[0008] (2) methanation of other streams to obtain natural gas;

[0009] Wherein, the raw gas comprises coke oven gas (COG) and a supplementary carbon source.

[0010] The second aspect of the present application provides a device for co-production of methanol and natural gas, which comprises:

[0011] A methanol synthesis reactor for converting raw gas to prepare methanol and other streams;

[0012] a methane synthesis reactor connected in series with the methanol synthesis reactor for converting the other materials from the methanol synthesis reactor to produce natural gas;

[0013] a first separator arranged between the methanol synthesis reactor and the methane synthesis reactor for separating the methanolization product to obtain methanol and other materials, and a second separator arranged at the outlet of the methane synthesis reactor product stream for separating the methanization product to obtain natural gas;

[0014] wherein the methanol synthesis reactor is an adiabatic fixed bed reactor and the methane synthesis reactor is an isothermal fixed bed reactor.

[0015] The third aspect of the present application provides a method for co-producing methanol and natural gas using the device provided in the second aspect, which is performed according to the method provided in the first aspect, and the method comprises:

[0016] Catalyst reduction: the methanolization catalyst in the methanol synthesis reactor is subjected to a first reduction with a reduction gas before feeding, and the methanization catalyst in the methane synthesis reactor is subjected to a second reduction with a reduction gas before feeding;

[0017] Heat exchange system establishment: 2-6 vt% of the raw material gas is preheated by a heater and then enters the methane synthesis reactor for reaction, and the boiler water is divided into two parts, one part of the water enters the methane synthesis reactor tube from bottom to top to remove heat for the reaction to generate heat exchange steam, which is exchanged with the raw material gas in the first heat exchanger to generate low-pressure steam; the other part of the water enters the fourth heat exchanger shell side to exchange heat with the discharged material of the methane synthesis reactor to generate heat exchange steam, which is exchanged with the other materials separated by the first gas-liquid separator in the third heat exchanger to generate heat exchange steam, which is exchanged with the discharged material of the methanol synthesis reactor in the second heat exchanger to generate low-pressure steam, and at the same time, the heater is closed when the 2-6 vt% of the raw material gas is finished feeding;

[0018] Operation: the heat exchange steam from the methane synthesis reactor tube is preheated by the raw material gas in the first heat exchanger and then enters the methanol synthesis reactor for reaction, the discharged material of the methanol synthesis reactor is exchanged with the heat exchange steam in the second heat exchanger to generate crude methanol after separation in the first gas-liquid separator, the other materials separated by the first gas-liquid separator are exchanged with the heat exchange steam in the third heat exchanger to enter the methane synthesis reactor for reaction, and the discharged material of the methane synthesis reactor is cooled by the fourth heat exchanger and then dehydrated in the second gas-liquid separator to obtain natural gas;

[0019] wherein,

[0020] The conditions of the first reduction include: the first reduction gas space velocity is 3000-6000 h -1The first reduction pressure is 0.5-1.0 MPa, the first reduction time is 10-14 h, and the first reduction temperature is 180-230 DEG C.

[0021] The second reduction gas space velocity is 3000-6000 h -1 The second reduction pressure is 0.5-1.0 MPa, the second reduction time is 5-10 h, and the second reaction temperature is 400-450 DEG C.

[0022] By the technical scheme, the application has the following beneficial effects:

[0023] The coke oven gas is subjected to methanolization and then methanation after being supplemented with carbon, so that methanol and methane are co-produced, and the single-pass selectivity of methane (the concentration of methane in natural gas) is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a preferred co-production device and process flow diagram of the application.

[0025] REFERENCE SIGNS

[0026] R1-methanol synthesis reactor, R2-methane synthesis reactor, E0-heater, E1-first heat exchanger, E2-second heat exchanger, E3-third heat exchanger, E4-water-gas heat exchanger, V1-first gas-liquid separator, V2-second gas-liquid separator, DWT-boiler. DETAILED DESCRIPTION

[0027] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the application. The endpoints of the ranges and the values are provided as approximations. Any numerical value, however, can inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0028] The first aspect of the application is a method for co-producing methanol and natural gas, which comprises:

[0029] (1) methanolization of raw gas to obtain methanol and other streams;

[0030] (2) methanation of the other streams to obtain natural gas;

[0031] The raw gas comprises coke oven gas and a carbon supplement.

[0032] The coke oven gas is subjected to methanolization and then methanation after carbon supplement, so that methanol and methane are co-produced, and the single-pass selectivity of methane (methane concentration in natural gas) is significantly improved.

[0033] In the present application, the composition of the coke oven gas is not particularly limited and can be obtained according to conventional methods in the art. According to one preferred embodiment of the present application, the composition of the coke oven gas comprises: CO: 8%, CO2: 3%, CH4: 27%, and H2: 62%.

[0034] In the present application, the type of the supplemental carbon source is not particularly limited as long as the object of the present application can be achieved. According to one preferred embodiment of the present application, the supplemental carbon source is selected from carbon monoxide and / or carbon dioxide. By adopting the foregoing preferred scheme, the methane concentration in the obtained natural gas can be further improved.

[0035] According to one preferred embodiment of the present application, the supplemental carbon source is carbon monoxide and carbon dioxide. By adopting the foregoing preferred scheme, the methane concentration in the obtained natural gas can be further improved.

[0036] In the present application, the volume space velocity of the raw material gas can be a conventional selection in the art. According to one preferred embodiment of the present application, the volume space velocity of the raw material gas is 8000-15000 h-1. -1 .

[0037] According to one preferred embodiment of the present application, when the supplemental carbon source is carbon dioxide, the molar ratio of the supplemental carbon source to the coke oven gas is 7-9:100.

[0038] According to one preferred embodiment of the present application, when the supplemental carbon source is carbon monoxide, the molar ratio of the supplemental carbon source to the coke oven gas is 11.5-12:100.

[0039] According to one preferred embodiment of the present application, when the supplemental carbon source is a mixed gas of carbon monoxide and carbon dioxide, the molar ratio of carbon monoxide to the coke oven gas is 5.5-6.8:100, based on the molar ratio of carbon dioxide to the coke oven gas being 4:100.

[0040] In the present application, the conditions for the methanolization can be a conventional selection in the art. According to one preferred embodiment of the present application, the conditions for the methanolization comprise: methanolization temperature 180-260℃, and methanolization pressure 3.0-5.0 MPa. By adopting the foregoing preferred scheme, the methane concentration in the obtained natural gas can be further improved.

[0041] In the present application, the methanation conditions can be conventional selection in the art, according to one preferred embodiment of the present application, the methanation conditions include: methanation temperature 250-380℃, methanation pressure 3.0-5.0MPa. By adopting the foregoing preferred scheme, the methane concentration in the obtained natural gas can be further improved.

[0042] In the present application, as long as the purpose of the present application can be achieved, the methanation catalyst can be conventional selection in the art, according to one preferred embodiment of the present application, the methanation catalyst is a copper-zinc-based catalyst. By adopting the foregoing preferred scheme, the methane concentration in the obtained natural gas can be further improved. For example, the methanation catalyst used in the present application uses copper and zinc bimetal as the active component, alumina as the carrier, and adopts the co-precipitation process to precipitate the copper and zinc bimetal active component, and then mixes and beats the alumina, ages, dries, granulates, calcines, and forms to obtain, wherein the alumina exists in one or more forms of η-Al2O3 or χ-Al2O3 or γ-Al2O3.

[0043] Specifically, according to one preferred embodiment of the present application, the preparation of the methanation catalyst includes:

[0044] 1) Dissolve copper salt and zinc salt in water to prepare a copper-zinc solution;

[0045] 2) Prepare an alkali solution; slowly add the solution to the copper-zinc solution under stirring to perform neutralization precipitation, and control the end point pH value at 7.0-7.5, and age;

[0046] 3) Add alumina to the aged copper-zinc mixture to perform mixing and beating;

[0047] 4) Wash, filter, dry at 100-130℃, and calcine at 260-360℃ the copper-zinc-aluminum mixture obtained after beating to obtain the methanation catalyst.

[0048] In the present application, as long as the purpose of the present application can be achieved, the methanation catalyst can be conventional selection in the art, according to one preferred embodiment of the present application, the methanation catalyst is a nickel-based catalyst. By adopting the foregoing preferred scheme, the methane concentration in the obtained natural gas can be further improved. For example, the methanation catalyst used in the present application uses nickel as the active component, one or more of potassium, cerium, copper, and lanthanum as the auxiliary agent, and magnesium-aluminum composite oxide as the carrier, and adopts the impregnation method to combine with the magnesium-aluminum carrier, and the alumina in the magnesium-aluminum spinel carrier exists in one or more forms of γ-Al2O3, θ-Al2O3, or α-Al2O3.

[0049] Specifically, according to one preferred embodiment of the present application, the preparation of the methanation catalyst includes:

[0050] 1) Dissolve magnesium salt in water to form magnesium solution;

[0051] 2) Add prepared alkali solution into magnesium solution under stirring to carry out neutralization and precipitation, and control the final pH value at 7.0-7.2;

[0052] 3) Remove the supernatant after the above materials are left still;

[0053] 4) Add aluminum oxide into the mother liquor to mix and beat up;

[0054] 5) After filtration, drying and calcination, the materials are pressed into shape;

[0055] 6) Dissolve one or more of the auxiliary salts such as potassium nitrate, cerium nitrate, copper nitrate and lanthanum nitrate in water to form auxiliary solution, and immerse the carrier in the auxiliary solution by equal volume impregnation method, and then take out, dry and calcine to obtain catalyst precursor;

[0056] 7) Dissolve nickel salt in water to form nickel solution, immerse the above catalyst precursor in the nickel solution by equal volume impregnation method, and then take out, dry and calcine to obtain methanation catalyst.

[0057] According to a preferred embodiment of the present application, the methanation catalyst prepared as described above is reduced by using reducing gas such as pure hydrogen before feeding, the reducing gas space velocity is 3000-6000h -1 , the reducing pressure is 0.5-1.0 MPa, the reducing time is 10-14h, and the reducing temperature is 180-230℃; the methanation catalyst prepared as described above is reduced by using reducing gas such as pure hydrogen before feeding, the reducing gas space velocity is 3000-6000h -1 , the reducing pressure is 0.5-1.0 MPa, the reducing time is 5-10h, and the reducing temperature is 400-450℃.

[0058] The second aspect of the present application provides a device for co-production of methanol and natural gas, which comprises:

[0059] a methanol synthesis reactor for converting raw gas to prepare methanol and other streams;

[0060] a methane synthesis reactor connected in series with the methanol synthesis reactor for converting other materials from the methanol synthesis reactor to prepare natural gas;

[0061] a first separator arranged on the connecting pipeline between the methanol synthesis reactor and the methane synthesis reactor, and a second separator arranged on the product stream outlet of the methane synthesis reactor, the first separator is used for separating methanation products to obtain methanol and other streams, and the second separator is used for separating methanation products to obtain natural gas;

[0062] The methanol synthesis reactor is an adiabatic fixed bed reactor, and the methane synthesis reactor is an isothermal fixed bed reactor.

[0063] By using the device, the process flow is short, the equipment is less, the circulating compressor is not needed, the operating pressure is low, and the methane concentration in the obtained natural gas can be further improved.

[0064] According to a preferred embodiment of the present application, the device further comprises a first heat exchanger arranged at the feed inlet of the methanol synthesis reactor.

[0065] According to a preferred embodiment of the present application, the device further comprises a second heat exchanger arranged at the discharge outlet of the methanol synthesis reactor.

[0066] According to a preferred embodiment of the present application, the device further comprises a third heat exchanger arranged at the feed inlet of the methane synthesis reactor.

[0067] According to a preferred embodiment of the present application, the device further comprises a fourth heat exchanger arranged at the discharge outlet of the methane synthesis reactor.

[0068] According to a preferred embodiment of the present application, the device further comprises a heater arranged in parallel with the third heat exchanger at the feed inlet of the methane synthesis reactor, and a boiler in communication with the methanation reactor and the fourth heat exchanger.

[0069] According to a preferred embodiment of the present application, the first heat exchanger, the second heat exchanger and the third heat exchanger are vapor-gas heat exchangers, and the fourth heat exchanger is a water-gas heat exchanger.

[0070] The third aspect of the present application provides a method for co-producing methanol and natural gas by using the device provided in the second aspect, which is performed according to the method provided in the first aspect, and the method comprises:

[0071] Catalyst reduction: the methanation catalyst in the methanol synthesis reactor is subjected to first reduction by using reduction gas before feeding, and the methanation catalyst in the methane synthesis reactor is subjected to second reduction by using reduction gas before feeding.

[0072] The heat exchange system is established: 2-6vt% of the raw material gas is preheated by the heater and then enters the methane synthesis reactor for reaction at the initial feeding, the boiler water is divided into two parts, one part of the water enters the methane synthesis reactor tube from bottom to top to remove heat for the reaction, to generate heat exchange steam 1, the heat exchange steam 1 is exchanged with the raw material gas in the first heat exchanger to generate low-pressure steam; the other part of the water enters the fourth heat exchanger shell side and exchanges heat with the methane synthesis reactor discharge material c to generate heat exchange steam 2, the heat exchange steam 2 exchanges heat with other streams b separated from the first gas-liquid separator in the third heat exchanger to generate heat exchange steam 3, the heat exchange steam 3 exchanges heat with the methanol synthesis reactor discharge material a in the second heat exchanger to generate low-pressure steam, at the same time, when the 2-6vt% of the raw material gas feeding is completed, the heater is closed;

[0073] Operation: the heat exchange steam 1 from the methane synthesis reactor tube exchanges heat with the raw material gas in the first heat exchanger, and then the raw material gas enters the methanol synthesis reactor for reaction, the methanol synthesis reactor discharge material a exchanges heat with the heat exchange steam 3 in the second heat exchanger, and then the methanol synthesis reactor discharge material a is separated in the first gas-liquid separator to generate crude methanol, the other streams b separated from the first gas-liquid separator exchanges heat with the heat exchange steam 2 in the third heat exchanger, and then the other streams b enter the methane synthesis reactor for reaction, the methane synthesis reactor discharge material c is cooled by the fourth heat exchanger, and then the methane synthesis reactor discharge material c is dehydrated in the second gas-liquid separator to obtain natural gas;

[0074] wherein,

[0075] The conditions of the first reduction include: the first reduction gas space velocity is 3000-6000h -1 -1.0MPa, the first reduction time is 10-14h, and the first reduction temperature is 180-230℃;

[0076] The conditions of the second reduction include: the second reduction gas space velocity is 3000-6000h -1 -1.0MPa, the second reduction time is 5-10h, and the second reaction temperature is 400-450℃.

[0077] As Figure 1 , the catalyst reduction process includes: the methanation catalyst in the methanol synthesis reactor is first reduced by the reducing gas before feeding, and the methanation catalyst in the methane synthesis reactor is secondly reduced by the reducing gas before feeding;

[0078] The starting-up and heat exchange process includes: 2-6 vt% of raw material gas is preheated by the heater E0 after being initially fed, and then enters the methane synthesis reactor R2 to react, the boiler (DWT) water is divided into two parts, one part of the water enters the methane synthesis reactor tube from bottom to top to remove heat for the reaction, to generate heat exchange steam 1, the heat exchange steam 1 exchanges heat with the raw material gas at the first heat exchanger E1 to generate low-pressure steam (LPS); the other part of the water enters the fourth heat exchanger E4 shell side to exchange heat with the methane synthesis reactor discharge material c to generate heat exchange steam 2, the heat exchange steam 2 exchanges heat with other streams b separated out from the first gas-liquid separator at the third heat exchanger E3 to generate heat exchange steam 3, the heat exchange steam 3 exchanges heat with the methanol synthesis reactor discharge material a at the second heat exchanger E2 to generate low-pressure steam (LPS), at the same time, 2-6 vt% of the raw material gas is fed, and the starting-up heater E0 is closed;

[0079] In the present application, the isothermal fixed bed reactor adopts a tube water cooling type heat removal system, the steam generated by the system can meet the temperature requirements of the methanol synthesis reactor and the methane synthesis reactor inlet gas, the E0 heater is stopped after feeding, and the steam generated by the process itself is used to preheat the synthesis gas, so that the energy saving effect is obvious.

[0080] The running process includes: the heat exchange steam 1 from the methane synthesis reactor R2 tube side preheats the raw material gas (COG + carbon source such as CO2) to a certain temperature such as 220 DEG C at the first heat exchanger E1, and then enters the methanol synthesis reactor R1 to react, the reaction temperature is 180-260 DEG C, the methanol synthesis reactor discharge material a exchanges heat with the heat exchange steam 3 at the second heat exchanger E2, and then is separated at a certain temperature such as 50 DEG C at the first gas-liquid separator V1 to generate crude methanol, other streams b separated out from the first gas-liquid separator exchanges heat with the heat exchange steam 2 at the third heat exchanger E3 to a certain temperature such as 300 DEG C, and then enters the methane synthesis reactor R2 to react, the reaction temperature is 250-380 DEG C, the methane synthesis reactor discharge material c is cooled to a certain temperature such as 50 DEG C by the fourth heat exchanger E4, and then is dehydrated in the second gas-liquid separator V2 to obtain natural gas (SNG).

[0081] The present application will be described in detail through examples below. In the following examples:

[0082] The raw materials are all commercially available products;

[0083] The components and contents in the reaction products are detected by Agilent 8890 gas chromatograph;

[0084]

[0085]

[0086] Preparation Example 1

[0087] Preparation of methanol synthesis catalyst:

[0088] 1) Dissolve 175 g of copper nitrate and 58 g of zinc nitrate in water to form a mixed solution;

[0089] 2) Dissolve sodium bicarbonate in water to form a solution with a molar concentration of 1.0 mol / L; slowly add the solution to the copper-zinc solution under stirring, and control the temperature at 50°C to perform neutralization and precipitation, and control the final pH value at 7.0-7.5, and then age at 80°C for 2 h;

[0090] 3) Add 14 g of alumina to the aged copper-zinc mixture, and mix and beat for 1 h;

[0091] 4) Wash and filter the copper-zinc-aluminum mixture, dry at 100-130°C for 4 h, and calcine at 260-360°C for 3 h to obtain a methanol synthesis catalyst with a mass ratio of Cu / Zn / Al of 60:20:7.

[0092] Among them, there are three forms of η-Al2O3, χ-Al2O3 and γ-Al2O3 in the alumina.

[0093] Preparation Example 2

[0094] Preparation of methane synthesis catalyst:

[0095] 1) Dissolve 800 g of magnesium nitrate hexahydrate in water to form a solution;

[0096] 2) Under stirring, add the prepared sodium bicarbonate solution with a molar concentration of 1.0 mol / L to the magnesium nitrate solution to perform neutralization, and control the reaction temperature at 80°C and the final pH value at 7.0-7.2;

[0097] 3) After the above materials are left still for 2 h, remove the supernatant;

[0098] 4) Add 350 g of γ-Al2O3 to the above mother liquor to mix and beat;

[0099] 5) After the materials are filtered, dried at 120°C for 3 h, and calcined at 900°C for 2 h, press them into carrier tablets with a diameter of Φ5х5;

[0100] 6) Dissolve one or more of potassium nitrate, cerium nitrate, copper nitrate and lanthanum nitrate in water to form a solution with a molar concentration of 0.0002 mol / ml in terms of metal potassium, cerium, copper and lanthanum; immerse the carrier in the mixed solution of one or more of potassium nitrate, cerium nitrate, copper nitrate and lanthanum nitrate in an equal volume by the water absorption rate of the carrier for 2 h, take it out, dry at 120°C for 1 h, and calcine at 400°C for 2 h to obtain a catalyst precursor;

[0101] 7) Dissolve nickel nitrate hexahydrate in water to prepare a solution with a molar concentration of 0.003 mol / ml based on metallic nickel. According to the water absorption rate of the above support, the above catalyst precursor is immersed in the nickel nitrate solution for 2 hours using the equal volume impregnation method. After being taken out, dried at 120℃ for 1 hour and calcined at 450℃ for 2 hours, a methane synthesis catalyst with a mass ratio of NiO: auxiliary oxide: magnesium aluminum composite support of 20:2:78 is obtained.

[0102] Example 1

[0103] according to Figure 1 The process flow shown involves reducing the catalyst used in the methanol synthesis reactor with pure hydrogen gas before feeding, at a space velocity of 4500 h⁻¹. -1 The pressure was 1.0 MPa, the reduction time was 12 h, and the reaction temperature was 200 °C. The catalyst used in the methane synthesis reactor was reduced with pure hydrogen gas before feeding, with a space velocity of 4500 h⁻¹. -1 The pressure was 1.0 MPa, the reduction time was 8 h, and the reaction temperature was 425 °C.

[0104] according to Figure 1 The process flow shown has a pressure of 3.0 MPa, and the composition of the feed gas (the molar ratio of supplementary carbon source carbon dioxide to coke oven gas is 8:100) is: CO: 7.41%, CO2: 10.19%, CH4: 25.0%, H2: 57.4%; the space velocity is 8000 h⁻¹. -1 ;

[0105] The heat exchange system is established as follows: 5% of the feed gas is preheated to 280°C by heater E0 and then enters the methane synthesis reactor R2. The reaction temperature is 350°C. Water cooling in the reactor tubes generates heat exchange steam 1. Heat exchange steam 1 exchanges heat with the feed gas at the first heat exchanger E1 to generate low-pressure steam LPS. The effluent c from the methane synthesis reactor exchanges heat with the boiler water in the shell side of the fourth heat exchanger E4 to generate heat exchange steam 2. Heat exchange steam 2 exchanges heat with other stream b separated from the first gas-liquid separator at the third heat exchanger E3 to generate heat exchange steam 3. Heat exchange steam 3 exchanges heat with effluent a from the methanol synthesis reactor at the second heat exchanger E2 to generate LPS.

[0106] During operation: the heat exchange steam 1 from the R2 pipe passes through the first heat exchanger E1 to preheat the raw material gas to 180°C, and then enters the methanol synthesis reactor R1 to react, the reaction temperature is 240°C, the material a from the methanol synthesis reactor passes through the third heat exchange steam 3 in the heat exchanger E2 to exchange heat, and then is separated at 50°C in the first gas-liquid separator V1 to obtain the crude methanol, the other material b separated from the first gas-liquid separator passes through the second heat exchange steam 2 in the third heat exchanger E3 to exchange heat, and then enters the methane synthesis reactor R2 to react at 250°C, the reaction temperature is 340°C, the material c from the methane synthesis reactor passes through the fourth heat exchanger E4 to cool to 50°C, and then is dehydrated in the second gas-liquid separator V2 to obtain the SNG.

[0107] Analysis shows that the total conversion rate of CO in the raw material gas is 100%, the content of METHA in the crude methanol is 95.3%, and the content of CH4 in the SNG is 97.7%.

[0108] Example 2

[0109] The same as example 1, except that the pressure is 3.0 MPa, and the raw material gas (the molar ratio of the supplementary carbon source carbon dioxide to the coke oven gas is 8.3:100) has the following composition: CO: 7.39%, CO2: 10.43%, CH4: 24.93%, H2: 57.25%; the space velocity of the raw material gas is 15000h -1 ;

[0110] The heat exchange system is established: 2% of the raw material gas is preheated to 300°C by the heater E0, and then enters the methane synthesis reactor R2, and the reaction temperature is 380°C;

[0111] During operation: the heat exchange steam 1 from the R2 pipe passes through the first heat exchanger E1 to preheat the raw material gas to 220°C, and then enters the methanol synthesis reactor R1 to react, the reaction temperature is 260°C, the other material b separated from the first gas-liquid separator passes through the second heat exchange steam 2 in the third heat exchanger E3 to exchange heat to 300°C, and then enters the methane synthesis reactor R2 to react, the reaction temperature is 360°C;

[0112] Analysis shows that the total conversion rate of CO in the raw material gas is 100%, the content of METHA in the crude methanol is 95.7%, and the content of CH4 in the SNG is 96.9%.

[0113] Example 3

[0114] The same as example 1, except that the raw material gas (the molar ratio of the supplementary carbon source carbon monoxide to the coke oven gas is 11.5:100) has the following composition: CO: 17.49%, CO2: 2.69%, CH4: 24.21%, H2: 55.61%; the pressure of the raw material gas is 5.0 MPa, and the space velocity of the raw material gas is 12000h -1 ;

[0115] Heat exchange system: 6% of the feed gas is preheated to 360°C by heater E0 and then enters the methane synthesis reactor R2, with a reaction temperature of 360°C;

[0116] During operation: the heat exchange steam 1 from the R2 tube passes through the first heat exchanger E1 to preheat the feed gas to 210°C, which then enters the methanol synthesis reactor R1 for reaction, with a reaction temperature of 250°C. The other stream b separated by the first gas-liquid separator is subjected to steam-gas heat exchange to 260°C by the third heat exchanger E3, and then enters the methane synthesis reactor R2 for reaction, with a reaction temperature of 360°C.

[0117] Analysis shows: the total conversion rate of CO in the feed gas is 100%, the METHA content in the crude methanol is 96.7%, and the CH4 content in the SNG is 96.2%.

[0118] Example 4

[0119] The same as Example 1, except that the pressure is 4.0 MPa, and the composition of the feed gas (the molar ratio of the supplementary carbon source carbon dioxide to coke oven gas is 7:100) is: CO: 7.48%, CO2: 9.35%, CH4: 25.23%, H2: 57.94%; the space velocity is 10000 h -1 ;

[0120] Heat exchange system: 4% of the feed gas is preheated to 280°C by heater E0 and then enters the methane synthesis reactor R2, with a reaction temperature of 380°C;

[0121] During operation: the heat exchange steam 1 from the R2 tube passes through the first heat exchanger E1 to preheat the feed gas to 220°C, which then enters the methanol synthesis reactor R1 for reaction, with a reaction temperature of 260°C. The other stream b separated by the first gas-liquid separator is subjected to steam-gas heat exchange to 280°C by the third heat exchanger E3, and then enters the methane synthesis reactor R2 for reaction, with a reaction temperature of 380°C.

[0122] Analysis shows: the total conversion rate of CO in the feed gas is 100%, the METHA content in the crude methanol is 96.8%, and the CH4 content in the SNG is 96.8%.

[0123] Example 5

[0124] The same as Example 1, except that the pressure is 3.0 MPa, and the composition of the feed gas (the molar ratio of the supplementary carbon source carbon dioxide to coke oven gas is 9:100) is: CO: 7.34%, CO2: 11.01%, CH4: 24.77%, H2: 56.88%; the space velocity is 10000 h -1 ;

[0125] Heat exchange system: 5% of the feed gas is preheated to 270°C by heater E0 and then enters the methane synthesis reactor R2, with a reaction temperature of 380°C;

[0126] During operation: the heat exchange steam 1 from the R2 tube passes through the first heat exchanger E1 to preheat the feed gas to 220°C, which then enters the methanol synthesis reactor R1 for reaction at a reaction temperature of 260°C. The other stream b separated by the first gas-liquid separator is subjected to steam-gas heat exchange with the second heat exchange steam 2 at the third heat exchanger E3 to 270°C, which then enters the methane synthesis reactor R2 for reaction at a reaction temperature of 350°C;

[0127] Analysis shows: the total conversion rate of CO in the feed gas is 100%, the METHA content in the crude methanol is 96.3%, and the CH4 content in the SNG is 96.5%.

[0128] Example 6

[0129] The same as Example 1, except that the pressure is 4.0 MPa, and the composition of the feed gas (the molar ratio of the supplementary carbon source carbon monoxide to coke oven gas is 12:100) is: CO: 17.86%, CO2: 2.68%, CH4: 24.11%, H2: 55.35%; the space velocity is 15000 h -1 ;

[0130] Heat exchange system: 5% of the feed gas is preheated to 270°C by heater E0 and then enters the methane synthesis reactor R2, with a reaction temperature of 380°C;

[0131] During operation: the heat exchange steam 1 from the R2 tube passes through the first heat exchanger E1 to preheat the feed gas to 220°C, which then enters the methanol synthesis reactor R1 for reaction at a reaction temperature of 260°C. The other stream b separated by the first gas-liquid separator is subjected to steam-gas heat exchange with the second heat exchange steam 2 at the third heat exchanger E3 to 270°C, which then enters the methane synthesis reactor R2 for reaction at a reaction temperature of 350°C;

[0132] Analysis shows: the total conversion rate of CO in the feed gas is 100%, the METHA content in the crude methanol is 96.3%, and the CH4 content in the SNG is 96.5%.

[0133] Example 7

[0134] The same as Example 1, except that the pressure is 3.0 MPa, and the composition of the feed gas (the molar ratio of the supplementary carbon source carbon dioxide to coke oven gas is 10:100) is: CO: 7.27%, CO2: 11.82%, CH4: 24.55%, H2: 56.36%; the space velocity is 8000 h -1 .

[0135] The analysis found that the total conversion rate of CO in the raw gas was 100%, the METHA content in the crude methanol was 95.4%, and the CH4 content in the SNG was 92.4%.

[0136] Example 8

[0137] The same as Example 1, except that the pressure was 3.0 MPa, and the raw gas (the supplementary carbon source was a mixture of carbon monoxide and carbon dioxide, and the molar ratio of carbon monoxide, carbon dioxide and coke oven gas was 6.8:4:100) had a composition of: CO: 13.36%, CO2: 6.32%, CH4: 24.37%, H2: 55.96%; the space velocity was 8000 h-1. -1 .

[0138] The analysis found that the total conversion rate of CO in the raw gas was 100%, the METHA content in the crude methanol was 96.4%, and the CH4 content in the SNG was 98.2%.

[0139] Example 9

[0140] The same as Example 1, except that the methanation synthesizer used an adiabatic fixed bed reactor.

[0141] During operation: since the methanation synthesizer used an adiabatic fixed bed reactor, the entire process used two-stage fixed bed reactors in series for methanolization and methanation, and there was no normal operation of the isothermal fixed bed reactor (tubular water-cooled type) to generate steam to maintain the reaction, so before the reaction started, the raw gas was preheated to 180°C using the first-stage electric heater and then entered the methanol synthesis reactor R1 for reaction, and the reaction temperature was 240°C. The material a from the methanol synthesis reactor outlet was subjected to water-steam heat exchange at the outlet, and then separated at 50°C in the first gas-liquid separator V1 to generate crude methanol. The other material b separated from the first gas-liquid separator was preheated to 250°C using the second-stage electric heater and then entered the methanation reactor R2 for reaction, and the reaction temperature was 640°C. The material c from the methanation reactor outlet was cooled to 50°C through multi-stage heat exchange and then dehydrated in the second gas-liquid separator V2 to obtain SNG. During the entire reaction process, in order to achieve the minimum use temperature of the catalyst, the inlet temperature conditions of each reactor were achieved by heating twice using electric heaters, but the methanation reaction was a strong exothermic reaction, and the adiabatic fixed bed reactor of the methanation could not remove a large amount of reaction heat, which not only limited the forward progress of the reaction, but also required several heat exchange devices to be set after the methanation reactor to cool the outlet gas, which would generate a large amount of steam. If the steam was not collected, energy would be wasted, and if the devices were added for recovery, the process would be too long.

[0142] The analysis found that the total conversion rate of CO in the raw gas was 100%, the METHA content in the crude methanol was 95.3%, and the CH4 content in the SNG was 77.2%.

[0143] Comparative Example 1

[0144] The same as Example 1, except that no additional carbon source is used.

[0145] Analysis found: the total conversion rate of CO in the raw gas was 100%, the METHA content in the crude methanol was 95.5%, and the CH4 content in the SNG was 70.8%.

[0146] The results show that, by using the technical solution of the present application, the excess hydrogen in the coke oven gas can be effectively utilized by adding a carbon source, and converted into useful methanol and methane. By using the preferred solution of the present application, the CH4 content in the SNG can reach more than 96%, meeting the national natural gas pipeline transportation standard.

[0147] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solution of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A process for the co-production of methanol and natural gas, characterized in that, The method is performed in a device, The device comprises: a methanol synthesis reactor for converting a feed gas to produce methanol and other streams; a methane synthesis reactor connected in series with the methanol synthesis reactor for converting the other streams from the methanol synthesis reactor to produce natural gas; a first separator arranged on a pipeline connecting the methanol synthesis reactor and the methane synthesis reactor, and a second separator arranged at an outlet of a product stream of the methane synthesis reactor, the first separator being used to separate methanation products to obtain methanol and other streams, and the second separator being used to separate methanation products to obtain natural gas; wherein the methanol synthesis reactor is an adiabatic fixed bed reactor, and the methane synthesis reactor is an isothermal fixed bed reactor; a first heat exchanger arranged at an inlet of the methanol synthesis reactor; a second heat exchanger arranged at an outlet of the methanol synthesis reactor; a third heat exchanger arranged at an inlet of the methane synthesis reactor; a heater arranged in parallel with the third heat exchanger at the inlet of the methane synthesis reactor; a fourth heat exchanger arranged at an outlet of the methane synthesis reactor; and a boiler connected with the methane synthesis reactor and the fourth heat exchanger; The method comprises: (1) methanating a feed gas to obtain methanol and other streams; (2) methanating the other streams to obtain natural gas; wherein the feed gas comprises coke oven gas and a supplementary carbon source; the methanation conditions include a methanation temperature of 180-260℃ and a methanation pressure of 3.0-5.0 MPa; the methanation conditions include a methanation temperature of 250-380℃ and a methanation pressure of 3.0-5.0 MPa; The heat exchange system is established as follows: 2-6 vt% of the feed gas is preheated by the heater and then enters the methane synthesis reactor for reaction, the boiler water is divided into two parts, one part of the water enters the methane synthesis reactor tubes from bottom to top to remove heat from the reaction to generate first heat exchange steam (1), the first heat exchange steam (1) exchanges heat with the feed gas at the first heat exchanger to generate low-pressure steam; the other part of the water enters the fourth heat exchanger shell side to exchange heat with the methane synthesis reactor outlet material (c) to generate second heat exchange steam (2), the second heat exchange steam (2) exchanges heat with the other streams (b) separated from the first gas-liquid separator at the third heat exchanger to generate third heat exchange steam (3), the third heat exchange steam (3) exchanges heat with the methanol synthesis reactor outlet material (a) at the second heat exchanger to generate low-pressure steam, and at the same time, 2-6 vt% of the feed gas is stopped at the end, and the heater is closed.

2. The method of claim 1, wherein, The supplementary carbon source is selected from carbon monoxide and / or carbon dioxide.

3. The method of claim 1, wherein, The volume space velocity of the raw material gas is 8000-15000h -1 ; and / or the molar ratio of the supplementary carbon source to the coke oven gas in the feed gas is 7-12:

100.

4. The method of claim 1, wherein, when the supplementary carbon source is carbon dioxide, the molar ratio of the supplementary carbon source to the coke oven gas is 7-9:100; or when the supplementary carbon source is carbon monoxide, the molar ratio of the supplementary carbon source to the coke oven gas is 11.5-12:100; or When the supplementary carbon source is a mixed gas of carbon monoxide and carbon dioxide, the molar ratio of carbon monoxide to coke oven gas is 5.5-6.8:100, and the molar ratio of carbon dioxide to coke oven gas is 4:

100.

5. The method of claim 1, wherein, The methanation catalyst is a copper-zinc-based catalyst.

6. The method of claim 1, wherein, The methanation catalyst is a nickel-based catalyst.

7. The method of claim 1, wherein, The first heat exchanger, the second heat exchanger and the third heat exchanger are vapor-gas heat exchangers, and the fourth heat exchanger is a water-gas heat exchanger.

8. The method of claim 1, wherein, The method comprises: Catalyst reduction: the methanation catalyst in the methanol synthesis reactor is subjected to first reduction with a reducing gas before feeding, and the methanation catalyst in the methane synthesis reactor is subjected to second reduction with a reducing gas before feeding; Heat exchange system establishment: 2-6 vt% of the raw material gas is preheated by a heater and then enters the methane synthesis reactor for reaction, the boiler water is divided into two parts, one part of the water enters the methane synthesis reactor tube from bottom to top to remove heat for the reaction to generate first heat exchange steam (1), and the first heat exchange steam (1) exchanges heat with the raw material gas at the first heat exchanger to generate low-pressure steam; the other part of the water enters the fourth heat exchanger shell side to exchange heat with the methane synthesis reactor discharge material (c) to generate second heat exchange steam (2), and the second heat exchange steam (2) exchanges heat with other streams (b) separated from the first gas-liquid separator at the third heat exchanger to generate third heat exchange steam (3), and the third heat exchange steam (3) exchanges heat with the methanol synthesis reactor discharge material (a) at the second heat exchanger to generate low-pressure steam, and at the same time, the heater is closed when 2-6 vt% of the raw material gas is fed; The running process comprises: the first heat exchange steam (1) from the methane synthesis reactor tube side preheats the raw material gas at the first heat exchanger and then enters the methanol synthesis reactor for reaction, the methanol synthesis reactor discharge material (a) exchanges heat with the third heat exchange steam (3) at the second heat exchanger, and then is separated at the first gas-liquid separator to generate crude methanol, other streams (b) separated from the first gas-liquid separator exchange heat with the second heat exchange steam (2) at the third heat exchanger and then enter the methane synthesis reactor for reaction, and the methane synthesis reactor discharge material (c) is cooled by the fourth heat exchanger and then dehydrated in the second gas-liquid separator to obtain natural gas; wherein, The first reduction conditions include: the first reduction gas space velocity is 3000-6000h -1 -1.0MPa, the first reduction time is 10-14h, and the first reduction temperature is 180-230℃. The conditions of the second reduction include: the second reduction gas space velocity is 3000-6000h -1 -1.0MPa, the second reduction time is 5-10h, and the second reaction temperature is 400-450℃.

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