Method for preparing synthesis gas by reforming methane and carbon dioxide

Abstract

The invention relates to a method for preparing synthesis gas by reforming methane and carbon dioxide, which comprises the following steps: feeding a hydrogen production raw material into a hydrodesulfurization reactor after first temperature rise, mixing the obtained desulfurized hydrogen production raw material with water vapor, then performing second temperature rise, and then feeding into a radiation unit of a hydrogen production converter for conversion reaction to obtain crude synthesis gas; the method comprises the following steps: feeding a mixed raw material obtained by mixing carbon dioxide and methane into a dry reforming reactor through a raw material inlet to be in contact with a reforming catalyst, performing catalytic reforming reaction, and obtaining reformed crude synthesis gas from a product outlet of the dry reforming reactor; and feeding the crude synthesis gas into a dry reforming reactor. According to the method, the high-temperature synthesis gas at the outlet of the hydrogen production reformer is used as a reaction heat source of the reforming reaction, the energy consumption of the preparation process is low, high-temperature steam is hardly generated in the preparation process, near-zero emission of carbon dioxide can be realized, meanwhile, the heat utilization efficiency of the hydrogen production reformer can be obviously improved, and energy expansion and efficiency improvement of a hydrogen production device are realized.

Description

Technical Field

[0001] The present invention belongs to the field of reforming synthesis gas, and specifically relates to a method for preparing synthesis gas by reforming methane and carbon dioxide. Background Art

[0002] The petrochemical industry produces a large amount of carbon dioxide emissions into the atmosphere every year, and large amounts of carbon dioxide emissions are one of the main causes of the greenhouse gas effect. Therefore, how to reduce and utilize carbon dioxide has attracted worldwide attention. Carbon dioxide in the petrochemical industry mainly comes from heating furnace fuel combustion, power station boiler combustion, and process emissions. Among the many carbon dioxide conversion and utilization technologies, carbon dioxide methane reforming synthesis gas technology can not only fully utilize carbon dioxide resources to obtain high-value-added chemicals, but also reduce the greenhouse gas effect, and has received great attention from academia and industry.

[0003] Carbon dioxide methane reforming reaction: CH4+CO2→2CO+2H2

[0004] From the reaction equation, it can be seen that the molar ratio of hydrogen to carbon monoxide is 1:1, which can be directly used for Fischer-Tropsch synthesis and carbonyl synthesis reactions. This reaction is a strong endothermic reaction with increased volume, and high temperature and low pressure are conducive to the reaction. From a thermodynamic point of view, the reaction temperature needs to be as high as 900°C to completely convert carbon dioxide and methane into synthesis gas.

[0005] The existing method of producing synthesis gas by reforming carbon dioxide and methane has a high reaction temperature requirement for the complete conversion of carbon dioxide and methane into synthesis gas, which will cause a series of problems such as high energy consumption, large pressure drop and poor adjustment flexibility. Summary of the invention

[0006] The purpose of the present disclosure is to provide a method for preparing synthesis gas by reforming methane and carbon dioxide. The method of the present invention fully utilizes the high-temperature synthesis gas at the outlet of the hydrogen production converter to provide reaction heat for the reforming reaction of methane and carbon dioxide. The preparation process has low energy consumption and almost no high-temperature steam is generated in the preparation process. At the same time, it can significantly improve the heat utilization efficiency of the hydrogen production converter and realize the expansion and efficiency improvement of the hydrogen production device.

[0007] In order to achieve the above object, the present invention provides a method for preparing synthesis gas by reforming methane and carbon dioxide, wherein the method comprises:

[0008] S1: sending the hydrogen production raw material into a hydrodesulfurization reactor after first heating to obtain a desulfurized hydrogen production raw material;

[0009] S2: mixing the desulfurized hydrogen production raw material with water vapor, heating it for a second time, and then sending it to the radiation unit of the hydrogen production converter for conversion reaction to obtain a crude synthesis gas;

[0010] S3: The mixed raw material obtained by mixing carbon dioxide and methane is sent to the dry reforming reactor through the raw material inlet to contact with the reforming catalyst to carry out catalytic reforming reaction, and a reformed crude synthesis gas is obtained from the product outlet of the dry reforming reactor; the crude synthesis gas is sent to the dry reforming reactor.

[0011] Optionally, the method further comprises:

[0012] The crude synthesis gas is fed into the heat medium inlet of the dry reforming reactor, and after heat exchange with the mixed raw material, the first synthesis gas is obtained from the heat supply outlet of the dry reforming reactor; alternatively, the crude synthesis gas, carbon dioxide and methane are mixed and used as the mixed raw material to enter the raw material inlet of the dry reforming reactor.

[0013] Optionally, in step S3, the temperature of the mixed raw material at the raw material inlet of the dry reforming reactor is 250-650° C., and the pressure is 0.3-4.5 MPa;

[0014] The method further comprises: before the mixed raw material of carbon dioxide and methane enters the raw material inlet of the dry reforming reactor, exchanging heat between the mixed raw material and the first synthesis gas in a heat exchanger to obtain a second synthesis gas, and sending the second synthesis gas to a steam generator for cooling; optionally, after the first synthesis gas is cooled by the steam generator, exchanging heat with the mixed raw material of carbon dioxide and methane in a heat exchanger;

[0015] Alternatively, the method further comprises:

[0016] Before the mixed raw material of carbon dioxide and methane enters the raw material inlet of the dry reforming reactor, the mixed raw material enters the convection unit of the hydrogen production converter to increase the temperature.

[0017] Optionally, the sulfur content of the hydrogen production feedstock is 5 to 200 ppm and the C3-C4 hydrocarbon content of the hydrogen production feedstock is 0.000001 to 5.0 mol%;

[0018] Step S1 includes, after the first heating, feeding the hydrogen production raw material into a hydrogenation reactor and a hydrodesulfurization reactor in sequence;

[0019] Optionally, step S2 includes mixing the desulfurized hydrogen production raw material with water vapor and sending it to a pre-conversion reactor for reaction after a second heating, and then sending it to the radiation unit after a third heating.

[0020] Optionally, the method further comprises: in step S3, the reformed raw synthesis gas is sequentially sent to a reforming reaction heat recovery unit, a carbon dioxide separation unit and a methane separation unit to obtain reformed synthesis gas.

[0021] Optionally, the method further comprises: allowing the carbon dioxide separated by the carbon dioxide separation unit to enter a downstream device and / or return to a dry reforming reactor;

[0022] The methane separated by the methane separation unit is fed into a downstream device, returned to a dry reforming reactor, used as a fuel for a convection unit, and used as a hydrogen production raw material, or used as one or more of the above.

[0023] Optionally, the reforming reaction heat recovery unit recovers heat in one or more of the following ways: recovering heat by generating steam through a waste heat boiler, recovering heat by heat exchange with hydrogen production reaction materials, recovering heat by heat exchange with carbon dioxide, recovering heat by heat exchange with methane, recovering heat by heat exchange with the mixed raw materials, and recovering heat by removing oxygen from the heat source through a deaerator.

[0024] Optionally, the method for separating carbon dioxide by the carbon dioxide separation unit is selected from one or more of membrane separation, pressure swing adsorption, wet alcohol amine method, low-temperature methanol washing process, low-temperature separation, hot potassium carbonate method and hydrated carbon dioxide separation method; the method for separating methane by the methane separation unit is selected from one or more of membrane separation, pressure swing adsorption and low-temperature deep freezing process.

[0025] Optionally, the first temperature increase and the second temperature increase are performed in a convection unit of the hydrogen production converter, by heat exchange through a reforming reaction product stream and / or by heat exchange through a hydrogen production product stream;

[0026] The hydrogen production raw material is selected from one or more of light hydrocarbons, naphtha, refinery dry gas, low-fraction gas and coke oven gas, and the reaction temperature of the hydrodesulfurization reactor is 150-400°C;

[0027] In the radiation unit, the conditions for the conversion reaction include: a reaction temperature of 750 to 950°C and a reaction pressure of 0.5 to 4.0 MPa; a temperature of the crude synthesis gas of 750 to 950°C and a pressure of 0.5 to 4.0 MPa;

[0028] In step S3, the dry reforming reactor is one or more of a shell-and-tube reactor, a fixed bed reactor, a radial bed reactor and an axial-radial reactor; the volume ratio of carbon dioxide to methane is (0.5-2):1; the conditions of the catalytic reforming reaction include: a reaction temperature of 550-850°C and a reaction pressure of 0.3-4.5Mpa; the reforming catalyst includes a reforming catalytic active component and an additive, and the reforming catalytic active component is selected from one or more of a nickel active component, a rhodium active component, a ruthenium active component, a platinum active component, a palladium active component and an iridium active component; the additive is selected from one or more of Al2O3, SiO2, SiC, molecular sieves, TiO2, MgO, rare earth metals and rare earth metal oxides.

[0029] Optionally, the molar ratio of hydrogen to carbon monoxide in the reformed crude synthesis gas is (0.1-3):1;

[0030] The content of methane in the reformed synthetic gas is less than 50 ppm, and the molar ratio of hydrogen to carbon monoxide in the reformed synthetic gas is (0.1-3):1.

[0031] Through the above technical scheme, the method of the present invention sets a dry reforming reactor at the outlet of the hydrogen production converter, and uses the high-temperature synthesis gas generated by the hydrogen production converter as the heat source for the methane carbon dioxide reforming reaction, which can significantly reduce the process energy consumption and cost of reforming synthesis gas, and the amount of high-temperature steam generated in the preparation process is small. At the same time, it can significantly improve the heat utilization efficiency of the hydrogen production converter, and realize the expansion and efficiency improvement of the hydrogen production device.

[0032] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 This is a schematic diagram of the process flow of Example 1 of the present invention.

[0035] Figure 2 This is a schematic diagram of the process flow of Example 2 of the present invention.

[0036] Figure 3 This is a schematic diagram of the process flow of Example 3 of the present invention.

[0037] Figure 4 This is a schematic diagram of the process flow of Example 4 of the present invention.

[0038] Figure 5 This is a schematic diagram of the process flow of Example 5 of the present invention.

[0039] Figure 6 This is a schematic diagram of the process flow of Example 6 of the present invention.

[0040] Figure 7 This is a schematic diagram of the process flow of Example 7 of the present invention.

[0041] Description of Reference Numerals

[0042] 1. Convection unit of hydrogen production reformer; 2. Radiation unit; 3. Hydrodesulfurization reactor; 4. Dry reforming reactor; 5. Hydrogenation reactor; 6. Pre-reforming reactor; 7. Heat exchanger; 8. Steam generator; 9. Carbon dioxide compressor; 10. Methane compressor; 11. Reforming reaction heat recovery unit; 12. Carbon dioxide separation unit; 13. Methane separation unit.

[0043] S1, hydrogen production raw material; S2, steam; S3, radiation unit feed; S4, air; S5, fuel gas; S6, crude synthesis gas; S7, first synthesis gas; S8, carbon dioxide; S9, methane; S10, reformed crude synthesis gas; S11, mixed raw material of preheated carbon dioxide and methane; S12, second synthesis gas; S13, third synthesis gas; S14, first reformed synthesis gas; S15, second reformed synthesis gas; S16, reformed synthesis gas; S17, carbon dioxide separated by the carbon dioxide separation unit; S18, methane separated by the methane separation unit; S19, flue gas. DETAILED DESCRIPTION

[0044] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0045] like Figure 1 As shown, the present invention provides a method for preparing synthesis gas by reforming methane and carbon dioxide, wherein the method comprises:

[0046] a. sending the hydrogen production raw material S1 to the hydrodesulfurization reactor 3 after the first heating to obtain the desulfurized hydrogen production raw material;

[0047] b. mixing the desulfurized hydrogen production raw material with water vapor S2, heating the mixture for the second time, and then feeding the mixture into the radiation unit 2 of the hydrogen production converter for conversion reaction to obtain a crude synthesis gas S6;

[0048] c. The mixed raw material obtained by mixing carbon dioxide and methane is sent to the dry reforming reactor 4 through the raw material inlet to contact with the reforming catalyst to carry out catalytic reforming reaction, and a reformed crude synthesis gas S10 is obtained from the product outlet of the dry reforming reactor 4; the crude synthesis gas S6 is sent to the dry reforming reactor 4.

[0049] The method of the present invention sets a dry reforming reactor at the outlet of the hydrogen production converter, and uses the high-temperature synthesis gas generated by the hydrogen production converter as the heat source of the methane carbon dioxide reforming reaction, which can significantly reduce the process energy consumption and cost of reforming synthesis gas, and the amount of high-temperature steam generated in the preparation process is relatively small. At the same time, it can significantly improve the heat utilization efficiency of the hydrogen production converter, and achieve energy expansion and efficiency improvement of the hydrogen production device. The carbon dioxide methane reforming synthesis gas production method proposed by the present invention is not only suitable for the quality improvement and capacity expansion of existing hydrocarbon hydrogen production devices, and the increase of synthesis gas production, but also suitable for occasions and devices with hydrogen and low hydrogen-carbon ratio synthesis gas demand in refining and chemical integration projects. The device has many product specifications and flexible operation.

[0050] In a specific embodiment of the present invention, Figure 1 As shown, the method further includes: sending the crude synthesis gas S6 to the heat medium inlet of the dry reforming reactor 4, exchanging heat with the mixed raw material, and obtaining the first synthesis gas S7 from the heat supply outlet of the dry reforming reactor 4. In the above embodiment, the high heat of the crude synthesis gas can be used to provide heat for the mixed raw material of carbon dioxide and methane, and the reaction temperature of the reforming reaction can be reached without an additional heat source, which significantly reduces the energy consumption and cost of the reforming synthesis gas production process and improves the energy utilization efficiency of the hydrogen production converter.

[0051] In another specific embodiment, Figure 7 As shown, the crude synthesis gas S6, carbon dioxide S8 and methane S9 are mixed as a mixed raw material and enter the raw material inlet of the dry reforming reactor 4. In the above embodiment, the crude synthesis gas, carbon dioxide and methane are mixed and sent to the dry reforming reactor. On the one hand, the crude synthesis gas is directly used as a high-temperature heat source to heat the reforming reaction raw material. On the other hand, in addition to the reaction between carbon dioxide and methane, the hydrogen in the crude synthesis gas can react chemically with the added carbon dioxide to adjust the hydrogen-to-carbon ratio of the synthesis gas product in a larger range, so that the preparation process has the advantages of flexible operation and can meet the diversified needs of downstream equipment and subsequent use.

[0052] In a specific embodiment of the present invention, in step S3, the temperature of the mixed raw material at the raw material inlet of the dry reforming reactor 4 is 250-650°C, preferably 350-550°C, and the pressure is 0.3-4.5Mpa, preferably 0.5-4.0Mpa;

[0053] In a specific embodiment of the present invention, Figure 5 As shown, the method further includes: before the mixed raw material of carbon dioxide and methane enters the raw material inlet of the dry reforming reactor 4, the mixed raw material is heat exchanged with the first synthesis gas S7 in the heat exchanger 7 to obtain the second synthesis gas S12, and the second synthesis gas S12 is sent to the steam generator 8 for cooling;

[0054] In another embodiment, if Figure 6As shown, the method further includes: before the mixed raw material of carbon dioxide and methane enters the raw material inlet of the dry reforming reactor 4, the first synthesis gas S7 is cooled by the steam generator 8, and then heat-exchanged with the mixed raw material of carbon dioxide and methane in the heat exchanger 7. In the above two embodiments, the mixed raw material of carbon dioxide and methane is heat-exchanged with the first synthesis gas and / or the second synthesis gas to increase the feed temperature of the reforming reaction, so that less steam or no steam is generated during the preparation process, which significantly reduces the energy consumption and cost of the reforming synthesis gas production process, and improves the energy utilization efficiency of the hydrogen production converter.

[0055] In a third specific embodiment of the present invention, the method further comprises:

[0056] Before the mixed feed of carbon dioxide and methane enters the feed inlet of the dry reforming reactor 4, the mixed feed enters the convection unit of the hydrogen production converter to increase its temperature.

[0057] In the above embodiment, a plurality of sets of heat exchange coils or components are arranged in the convection unit of the hydrogen production converter, which can not only preheat the hydrogen production raw materials and combustion air, but also provide heat for the mixed raw materials of carbon dioxide and methane, thereby reducing the temperature of the flue gas at the outlet of the radiation unit, thereby further improving the energy utilization efficiency of the hydrogen production converter.

[0058] In a specific embodiment of the present invention, Figure 2 As shown, step S1 includes, after the hydrogen production raw material S1 is heated for the first time, feeding it into the hydrogenation reactor 5 and the hydrodesulfurization reactor 3 in sequence. The reaction temperature of the hydrogenation reactor 5 is 120-350°C and the pressure is 0.5-4.5MPa; the reaction temperature of the hydrodesulfurization reactor 3 is 120-350°C and the pressure is 0.5-4.5MPa.

[0059] The above implementation is applicable to hydrogen production raw materials with a high sulfur content. The hydrogenation reactor converts the organic sulfur in the hydrogen production raw materials into hydrogen sulfide, and then the sulfur content of the raw gas is reduced to below 0.3 ppm by the hydrodesulfurization reactor and sent to the hydrogen production conversion furnace tube, thereby further improving the quality and performance of the prepared synthesis gas.

[0060] like Figure 3 As shown, in another specific embodiment of the present invention, the hydrogen production feedstock contains 0.000001-5.0 mol% of C3-C4 hydrocarbons, step S1 includes, after the first heating, the hydrogen production feedstock S1 is sequentially sent to the hydrogenation reactor 5 and the hydrodesulfurization reactor 3, step S2 includes, the desulfurized hydrogen production feedstock obtained in step S1 is mixed with water vapor S2 and sent to the pre-conversion reactor 6 for reaction after the second heating, and then sent to the radiation unit 2 after the third heating. The reaction temperature of the pre-conversion reactor 6 is 120-450°C, and the pressure is 0.5-4.5MPa.

[0061] The above embodiment is applicable to hydrogen production raw materials containing heavy hydrocarbon components. The pre-conversion reactor 6 converts the heavy hydrocarbon components into small molecular methane, avoiding carbon deposition and deactivation of the reformer tubes, and further extending the operating cycle of the hydrogen production reformer.

[0062] In a specific embodiment of the present invention, the method further includes: in step S3, the reformed raw synthesis gas S10 is sequentially sent to the reforming reaction heat recovery unit 11, the carbon dioxide separation unit 12 and the methane separation unit 13 to obtain the reformed synthesis gas S16.

[0063] In another specific embodiment of the present invention, the method further comprises: allowing the carbon dioxide separated by the carbon dioxide separation unit 12 to enter a downstream device and / or return to the dry reforming reactor 4;

[0064] The methane separated by the methane separation unit 13 enters a downstream device, returns to the dry reforming reactor 4, is used as a fuel for the radiation unit 2, and is used as one or more of the hydrogen production raw materials S1.

[0065] In the above embodiment, after the reformed crude synthesis gas is cooled by the heat recovery unit, it is separated by the carbon dioxide separation unit to obtain unreacted carbon dioxide, and the unreacted carbon dioxide can be circulated back to the raw material inlet of the dry reforming reactor to continue the catalytic reforming reaction, further improving the utilization rate of carbon dioxide. The reformed crude synthesis gas from which carbon dioxide is separated is separated into unreacted methane by the methane separation unit, and the unreacted methane can be circulated back to the raw material inlet of the dry reforming reactor to continue the catalytic reforming reaction, which, on the one hand, improves the utilization rate of methane, and on the other hand, can meet the quality requirements of synthesis gas with low or no methane content in downstream facilities, and the product quality is excellent and has good stability.

[0066] In a specific embodiment of the present invention, the reforming reaction heat recovery unit 11 recovers heat in one or more of the following ways: recovering heat by generating steam through a waste heat boiler, recovering heat by heat exchange with hydrogen production reaction material S1, recovering heat by heat exchange with carbon dioxide S8, recovering heat by heat exchange with methane S9, recovering heat by heat exchange with mixed raw materials, and recovering heat by deoxidizing heat source through a deaerator. In the above embodiment, heat is further recovered by the reforming reaction heat recovery unit and used for preheating carbon dioxide and methane, further improving the heat utilization rate of the preparation process, and can further improve the quality and performance of the prepared synthesis gas.

[0067] In a specific embodiment of the present invention, the method for separating carbon dioxide by the carbon dioxide separation unit 12 is selected from one or more of membrane separation, pressure swing adsorption (PSA), wet alcohol amine method, low-temperature methanol washing process, low-temperature separation, hot potassium carbonate method and hydrated carbon dioxide separation method, preferably wet alcohol amine method, low-temperature methanol washing process or pressure swing adsorption (PSA); the method for separating methane by the methane separation unit 13 is selected from one or more of membrane separation, pressure swing adsorption (PSA) and low-temperature cryogenic process, preferably low-temperature cryogenic process.

[0068] In a specific embodiment of the present invention, the first temperature increase and the second temperature increase are performed in the convection unit 1 of the hydrogen production converter; in another specific embodiment of the present invention, the first temperature increase and the second temperature increase are performed by heat exchange through the reforming reaction product logistics. In the above embodiment, the high temperature of the reforming synthetic gas is fully utilized to provide heat for the reaction through heat exchange of the reforming reaction product logistics, thereby improving the energy utilization efficiency of the reaction system and further reducing the process energy consumption and cost; in another specific embodiment of the present invention, the first temperature increase and the second temperature increase are performed by heat exchange of the hydrogen production product logistics. In the above embodiment, the high temperature heat source of the reaction products of the hydrogen production converter is fully utilized through heat exchange of the hydrogen production product logistics, thereby further improving the energy utilization efficiency of the hydrogen production converter, which has obvious environmental advantages.

[0069] In a specific embodiment of the present invention, the sulfur content of the hydrogen production feedstock is 5 to 200 ppm, preferably 10 to 150 ppm, and the C3-C4 hydrocarbon content of the hydrogen production feedstock is 0.000001 to 5.0 mol%, preferably 0.000001 to 1.5 mol%.

[0070] In a specific embodiment of the present invention, the hydrogen production raw material is selected from one or more of light hydrocarbons, naphtha, refinery dry gas, low-fraction gas and coke oven gas. Furthermore, the light hydrocarbon in the present invention is preferably natural gas or liquefied gas. Natural gas is mainly methane and contains a small amount of ethane, propane and butane. In addition, it also contains a small amount of hydrogen sulfide and low molecular weight mercaptans, which are easily removed by a hydrodesulfurization reactor. The main components of liquefied gas are propane, propylene, butane and butene, and can be a mixture of one or more of the above hydrocarbons, and It contains a small amount of pentane, pentene and trace sulfide impurities; naphtha is preferably selected from one or more of reformed naphtha, hydrogenated naphtha or catalytic naphtha; refinery dry gas mainly refers to the non-condensable gas produced and recovered in the refinery process, and its main components are ethylene, propylene and methane, ethane, propane and butane, etc.; low-fraction gas mainly refers to the gas separated by a low-pressure separator and some light hydrocarbons; the main components of coke oven gas are hydrogen and methane, and it contains a small amount of carbon monoxide, carbon dioxide, nitrogen and other hydrocarbons. In the above embodiment, for example, when selecting unsaturated hydrocarbon hydrogen production feedstock, in order to avoid carbon deposition and deactivation of the reforming catalyst, it is necessary to set a hydrogenation reactor before entering the hydrodesulfurization reactor to hydrogenate and saturate the unsaturated hydrocarbons to avoid carbon deposition and deactivation of the catalyst in the dry reforming reactor; or, when selecting light hydrocarbons or naphtha and other hydrogen production feedstocks, it is necessary to set a pre-conversion reactor before entering the hydrogen production converter to crack the macromolecular hydrocarbons into small molecules such as methane and ethane to extend the service life of the reforming catalyst in the hydrogen production converter tube; the reaction temperature of the hydrodesulfurization reactor is 120 to 350°C, preferably 180 to 250°C.

[0071] In the radiation unit 2, the conditions for the conversion reaction include: a reaction temperature of 750 to 950°C, preferably 800 to 900°C, a reaction pressure of 0.5 to 4.0 MPa, preferably 1.0 to 3.5 MPa; a temperature of the crude synthesis gas S6 of 750 to 950°C, preferably 800 to 900°C, and a pressure of 0.5 to 4.0 MPa, preferably 1.0 to 3.5 MPa;

[0072] In step S3, the dry reforming reactor 4 is one or more of a shell-and-tube reactor, a fixed bed reactor, a radial bed reactor and an axial radial reactor, preferably a shell-and-tube reactor; the volume ratio of carbon dioxide to methane is (0.5-2):1, preferably (0.8-1.2):1; the conditions for the catalytic reforming reaction include: a reaction temperature of 550-850°C, preferably 600-750°C, a reaction pressure of 0.3-4.5 MPa, preferably 1.0-3.5 MPa; the reforming catalyst includes a reforming catalytic active component and The auxiliary agent, the reforming catalytic active component is selected from one or more of the nickel active component, rhodium active component, ruthenium active component, platinum active component, palladium active component and iridium active component, preferably nickel active component, rhodium active component, ruthenium active component, platinum active component and palladium active component; the auxiliary agent is selected from one or more of Al2O3, SiO2, SiC, molecular sieve, TiO2, MgO, rare earth metals and rare earth metal oxides, preferably Al2O3, SiO2, SiC, TiO2, MgO, rare earth metals and rare earth metal oxides.

[0073] In the above embodiment, when the dry reforming reactor is a tubular reactor, the reforming catalyst can be loaded inside the tube or outside the tube, preferably the reforming catalyst is loaded inside the tube. The space inside the tube is fluidly connected to the raw material inlet and product outlet of the dry reforming reactor, and the space outside the tube is fluidly connected to the heat medium inlet of the dry reforming reactor.

[0074] In the present invention, the appropriate volume ratio of carbon dioxide to methane can be adjusted according to the requirements of the downstream equipment for the composition and quality of the synthesis gas, and the process flow is flexible in operation, which has the advantage of being able to meet diverse needs. The reforming catalyst selected in the present invention has good low-temperature activity and excellent anti-carbon deposition performance, and can more fully utilize the synthesis gas heat at the outlet of the hydrogen production converter, and can ensure the stability of the device under long-term operation of the device.

[0075] In a specific embodiment of the present invention, the molar ratio of hydrogen to carbon monoxide in the reformed crude synthesis gas S10 is (0.1-3):1, preferably (0.8-1.5):1;

[0076] The methane content in the reformed synthetic gas S16 is less than 50 ppm, preferably less than 30 ppm, and the molar ratio of hydrogen to carbon monoxide in the reformed synthetic gas S16 is (0.1-3):1, preferably (0.8-1.2):1.

[0077] The reformed synthetic gas prepared by the present invention has a low hydrogen-to-carbon ratio and high added value, and can be directly used as a raw material for preparing high-carbon alcohols or carbonyl oxygen-containing compounds by Fischer-Tropsch synthesis.

[0078] The present invention is further described below by way of examples, but the present invention is not limited thereto.

[0079] Example 1

[0080] The hydrogen production raw material of this embodiment is natural gas, the sulfur content of natural gas is 20ppm, and the fuel of the hydrogen production converter is natural gas and the desorbed gas separated by the PSA unit. The dry reforming reactor used in this embodiment is a shell-and-tube reactor, and the shell-and-tube reactor is filled with a reforming catalyst. The active component of the reforming catalyst is a nickel-ruthenium active component, and the auxiliary agent is Al2O3. The preparation process flow chart is shown in FIG. Figure 1 shown.

[0081] a. The hydrogen production raw material S1 is heated to 280°C and sent to the hydrodesulfurization reactor 3 to obtain a desulfurized hydrogen production raw material.

[0082] b. Mix the desulfurized hydrogen-producing raw material of step a with water vapor S2, heat it to 540°C, and feed it into the radiation unit 2 of the hydrogen production converter for conversion reaction to obtain a crude synthesis gas S6, wherein the reaction temperature is 860°C, the reaction pressure is 3.4Mpa, the temperature of the crude synthesis gas S6 is 860°C, the pressure is 3.4Mpa, the catalyst used for the conversion reaction is a ruthenium active component, and the sulfur content of the radiation unit feed S3 is 5ppm.

[0083] c. The crude synthesis gas S6 of step b is fed into the heat medium inlet of the dry reforming reactor 4 to provide heat for the catalytic reforming reaction, and after heat exchange with the mixed raw material, the first synthesis gas S7 is obtained from the heat supply outlet of the dry reforming reactor 4; the carbon dioxide S8 and methane S9 are respectively pressurized to 2.55 MPa by a compressor and then mixed to obtain a mixed raw material, and the mixed raw material is fed into the raw material inlet of the dry reforming reactor 4 to contact with the reforming catalyst to carry out a catalytic reforming reaction, and a reformed crude synthesis gas S10 is obtained from the product outlet of the dry reforming reactor 4. Among them, the temperature of the mixed raw material at the raw material inlet of the dry reforming reactor 4 is 450°C, the temperature of the catalytic reforming reaction is 600°C, the reaction pressure is 2.5 MPa, the temperature of the crude synthesis gas S6 is 850°C, the pressure is 3.2 MPa, and the temperature of the first synthesis gas S7 is 710°C, and the pressure is 3.15 MPa.

[0084] Example 2

[0085] The hydrogen production raw material in this embodiment is refinery dry gas, and the sulfur content of the hydrogen production raw material is 150ppm. Figure 2 shown.

[0086] The method of Example 1 is adopted, the only difference being that a separate hydrogenation reactor 5 is provided before the hydrodesulfurization reactor 3. The sulfur content of the radiation unit feed S3 is less than 0.3 ppm.

[0087] Example 3

[0088] The hydrogen production raw material of this embodiment is light hydrocarbon from refinery, and the C3-C4 hydrocarbon content of the hydrogen production raw material is 1.5 mol%. Figure 3 shown.

[0089] The method of Example 2 is adopted, the only difference being that a pre-conversion reactor 6 is provided before the hydrogen production raw material enters the hydrogen production conversion furnace tube.

[0090] Example 4

[0091] Preparation process flow chart Figure 4 shown.

[0092] The method of Example 1 is adopted, and the only difference is that the reformed crude synthesis gas S10 obtained in step c is sequentially sent to the reforming reaction heat recovery unit 11, the carbon dioxide separation unit 12 and the methane separation unit 13 to obtain the reformed synthesis gas S16. Among them, the reforming reaction heat recovery unit 11 is mainly equipped with equipment such as a steam generator, a raw material heat exchanger and a deaerator; the carbon dioxide separation unit 12 uses the MDEA wet decarbonization method to separate unreacted carbon dioxide; and the methane separation unit 13 uses a low-temperature deep-cold process to separate unreacted methane.

[0093] Example 5

[0094] Preparation process flow chart Figure 5 shown.

[0095] The method of Example 1 is adopted, and the only difference is that the first synthesis gas S7 in step c is sent to the tube side of the heat exchanger 7 to obtain the second synthesis gas S12; carbon dioxide and methane are respectively pressurized to 3.0 MPa by a compressor and then mixed to obtain a mixed raw material, and the mixed raw material is sent to the shell side of the heat exchanger 7, and after heat exchange with the first synthesis gas S7, it is sent to the raw material inlet of the dry reforming reactor 4, contacts with the reforming catalyst, performs catalytic reforming reaction, and obtains the reformed crude synthesis gas S10 from the product outlet of the dry reforming reactor 4. Among them, the temperature of the mixed raw material after heat exchange is 450°C.

[0096] Example 6

[0097] Preparation process flow chart Figure 6 shown.

[0098] The method of Example 1 is adopted, and the only difference is that the first synthesis gas S7 in step c is sent to the steam generator 8 to obtain the second synthesis gas S12, and the second synthesis gas S12 is sent to the heat exchanger 7 to obtain the third synthesis gas S13; carbon dioxide and methane are respectively pressurized to 3.0 MPa by a compressor and then mixed to obtain a mixed raw material, and the mixed raw material is sent to the shell side of the heat exchanger 7, and after heat exchange with the second synthesis gas S12, it is sent to the raw material inlet of the dry reforming reactor 4, contacted with the reforming catalyst, and catalytic reforming reaction is carried out, and the reformed crude synthesis gas S10 is obtained from the product outlet of the dry reforming reactor 4. Among them, the temperature of the mixed raw material after heat exchange is 350°C.

[0099] Example 7

[0100] The dry reforming reactor used in this embodiment is a fixed bed reactor, the active component of the reforming catalyst is a nickel-rhodium active component, and the auxiliary agent is Al2O3-rare earth metal. Figure 7 shown.

[0101] The method of Example 1 is adopted, except that, in step c, the crude synthesis gas S6 of step b, the pressurized carbon dioxide S8 and methane S9 are mixed as a mixed raw material and sent to the raw material inlet of the dry reforming reactor 4, contacted with the reforming catalyst, and subjected to a catalytic reforming reaction, and a reformed crude synthesis gas S10 is obtained from the product outlet of the dry reforming reactor 4. The temperature of the mixed raw material at the raw material inlet of the dry reforming reactor 4 is 480° C., the temperature of the catalytic reforming reaction is 600° C., and the reaction pressure is 2.9 MPa.

[0102] Test Case

[0103] The reformed raw synthesis gas S10 of Examples 1 to 7 and the reformed synthesis gas S16 of Example 4 were tested as follows:

[0104] The molar ratio of hydrogen to carbon monoxide in the synthesis gas is measured by an online analyzer arranged on the synthesis gas product line;

[0105] The methane content was determined by gas chromatography, and the steam amount was read directly by a mass flow meter set in the steam line.

[0106] Table 1

[0107]

[0108]

[0109] According to the test results in Table 1, it can be seen that the preparation method provided by the present invention can significantly reduce the process energy consumption and cost of reforming synthesis gas, and the amount of steam generated in the preparation process is relatively small. At the same time, it can significantly improve the heat utilization efficiency of the hydrogen production converter, and realize the capacity expansion and efficiency improvement of the hydrogen production device; on the other hand, the unconverted carbon dioxide and methane in the crude synthesis gas, the carbon dioxide separated from the desorbed gas, and the carbon dioxide separated from the flue gas in the hydrogen production converter can continue to be used as reforming reaction raw materials for catalytic reforming reaction, which has obvious environmental advantages.

[0110] It can be seen from the test results of Examples 1-7 that the hydrogen-carbon ratio of the reformed synthetic gas prepared by the preparation method of the present invention can meet the diversified needs of downstream equipment and subsequent use, the reformed synthetic gas has high added value, the amount of steam generated by the device is relatively low, the environmental protection advantage is obvious, and the equipment operation cycle and service life are long; the traditional synthesis gas preparation can adopt natural gas steam reforming process, coal gasification process and coke oven gas conversion process, among which natural gas steam reforming is more widely used. Natural gas and water vapor generate crude synthesis gas under a certain pressure (3.0MPa), temperature (850-900℃) and nickel-based reforming catalyst, and synthesis gas is obtained after cooling and liquid separation. The processing energy consumption of the traditional natural gas to synthesis gas process is about 950kgoe / t (synthesis gas). Compared with the traditional technology process, the energy consumption of the present application process is reduced.

[0111] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0112] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0113] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing synthesis gas by reforming methane and carbon dioxide, wherein: The method includes: a. feeding the hydrogen production raw material (S1) into a hydrodesulfurization reactor (3) after first heating to obtain a desulfurized hydrogen production raw material; b. mixing the desulfurized hydrogen production raw material with water vapor (S2), heating the mixture for a second time, and then feeding the mixture into the radiation unit (2) of the hydrogen production converter for conversion reaction to obtain a crude synthesis gas (S6); c. The mixed raw material obtained by mixing carbon dioxide and methane is sent to the dry reforming reactor (4) through the raw material inlet to contact with the reforming catalyst to carry out a catalytic reforming reaction, and a reformed crude synthesis gas (S10) is obtained from the product outlet of the dry reforming reactor (4); the crude synthesis gas (S6) is sent to the dry reforming reactor (4).

2. The method according to claim 1, wherein: The method further includes: The crude synthesis gas (S6) is fed into the heat medium inlet of the dry reforming reactor (4), and after heat exchange with the mixed raw material, a first synthesis gas (S7) is obtained from the heat supply outlet of the dry reforming reactor (4); alternatively, the crude synthesis gas (S6), carbon dioxide (S8) and methane (S9) are mixed as the mixed raw material and enter the raw material inlet of the dry reforming reactor (4).

3. The method according to claim 1, wherein: In step c, the temperature of the mixed raw material at the raw material inlet of the dry reforming reactor (4) is 250-650° C. and the pressure is 0.3-4.5 MPa; The method further comprises: before the mixed raw material of carbon dioxide and methane enters the raw material inlet of the dry reforming reactor (4), exchanging heat between the mixed raw material and the first synthesis gas (S7) in a heat exchanger (7) to obtain a second synthesis gas (S12), and sending the second synthesis gas (S12) into a steam generator (8) for cooling; Alternatively, the method further comprises, before the mixed raw material of carbon dioxide and methane enters the raw material inlet of the dry reforming reactor (4), cooling the first synthesis gas (S7) through a steam generator (8), and then exchanging heat with the mixed raw material of carbon dioxide and methane in a heat exchanger (7); Alternatively, the method further comprises: Before the mixed raw material of carbon dioxide and methane enters the raw material inlet of the dry reforming reactor (4), the mixed raw material is heated by entering the convection unit of the hydrogen production converter.

4. The method according to claim 1, wherein: The sulfur content of the hydrogen production raw material is 5 to 200 ppm, and the C3-C4 hydrocarbon content of the hydrogen production raw material is 0.000001 to 5.0 mol%; Step S1 comprises: sending the hydrogen production raw material (S1) into a hydrogenation reactor (5) and a hydrodesulfurization reactor (3) in sequence after a first heating; Optionally, step S2 comprises mixing the desulfurized hydrogen production raw material with water vapor (S2) and sending it to a pre-conversion reactor (6) for reaction after a second heating, and then sending it to the radiation unit (2) after a third heating.

5. The method according to claim 1, wherein: The method further comprises: in step S3, the reformed raw synthesis gas (S10) is sequentially sent to a reforming reaction heat recovery unit (11), a carbon dioxide separation unit (12) and a methane separation unit (13) to obtain a reformed synthesis gas (S16).

6. The method according to claim 5, wherein: The method further comprises: allowing the carbon dioxide separated by the carbon dioxide separation unit (12) to enter a downstream device and / or return to a dry reforming reactor (4); The methane separated by the methane separation unit (13) enters a downstream device, returns to the dry reforming reactor (4), is used as a fuel for the radiation unit (2), and is used as a hydrogen production raw material (S1), or is used as one or more of the above.

7. The method according to claim 5, wherein: The reforming reaction heat recovery unit (11) recovers heat by generating steam through a waste heat boiler, recovering heat through heat exchange with hydrogen production reaction materials (S1), recovering heat through heat exchange with carbon dioxide (S8), recovering heat through heat exchange with methane (S9), recovering heat through heat exchange with the mixed raw material, and recovering heat through a deoxidizer deoxygenation heat source. One or more of the methods.

8. The method according to claim 5, wherein: The method for separating carbon dioxide in the carbon dioxide separation unit (12) is selected from one or more of membrane separation, pressure swing adsorption, wet alcohol amine method, low-temperature methanol washing process, low-temperature separation, hot potassium carbonate method and hydrated carbon dioxide separation method; the method for separating methane in the methane separation unit (13) is selected from one or more of membrane separation, pressure swing adsorption and low-temperature deep freezing process.

9. The method according to claim 1, wherein: The first temperature increase and the second temperature increase are performed in the convection unit (1) of the hydrogen production reformer, through heat exchange of the reforming reaction product stream and / or through heat exchange of the hydrogen production product stream; The hydrogen production raw material is selected from one or more of natural gas, liquefied gas, light hydrocarbons, naphtha, refinery dry gas, low-fraction gas and coke oven gas, and the reaction temperature of the hydrodesulfurization reactor is 150-400°C; In the radiation flow unit (2), the conditions for the conversion reaction include: a reaction temperature of 750 to 950°C and a reaction pressure of 0.5 to 4.0 MPa; a temperature of the crude synthesis gas (S6) of 750 to 950°C and a pressure of 0.5 to 4.0 MPa; In step S3, the dry reforming reactor (4) is one or more of a shell-and-tube reactor, a fixed bed reactor, a radial bed reactor and an axial radial reactor; the volume ratio of carbon dioxide to methane is (0.5-2):1; the conditions of the catalytic reforming reaction include: a reaction temperature of 550-850°C and a reaction pressure of 0.3-4.5Mpa; the reforming catalyst includes a reforming catalytic active component and an auxiliary agent, and the reforming catalytic active component is selected from one or more of a nickel active component, a rhodium active component, a ruthenium active component, a platinum active component, a palladium active component and an iridium active component; the auxiliary agent is selected from one or more of Al2O3, SiO2, SiC, molecular sieves, TiO2, MgO, rare earth metals and rare earth metal oxides.

10. The method according to claim 1, wherein: The molar ratio of hydrogen to carbon monoxide in the reformed crude synthesis gas (S10) is (0.1-3):1; The content of methane in the reformed synthetic gas (S16) is less than 50 ppm, and the molar ratio of hydrogen to carbon monoxide in the reformed synthetic gas (S16) is (0.1-3):1.

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