Method and system for preparing synthesis gas with low hydrogen-carbon ratio

Abstract

The invention belongs to the field of carbon dioxide methane reforming, and discloses a low-hydrogen-carbon-ratio synthesis gas preparation method and a low-hydrogen-carbon-ratio synthesis gas preparation system. The system comprises a dry reforming reactor, a carbon dioxide feeding pipeline, a methane feeding pipeline, a compression device, a hydrogen production reaction device, a reforming crude synthesis gas treatment device and a hydrogen production synthesis gas treatment device. The method not only solves the problems of easy catalyst deactivation, high energy consumption and the like in the technology for preparing the synthesis gas by reforming carbon dioxide methane, but also obtains the synthesis gas with low hydrogen-carbon ratio, and is especially suitable for being used as a raw material for preparing methanol and ethylene glycol. According to the invention, the purpose of increasing the yield of hydrogen (synthesis gas) can be achieved on the basis of not changing the existing hydrogen production furnace. As a typical blue hydrogen preparation method, carbon dioxide is turned into wealth, and economic and environmental benefits are obvious.

Description

Technical Field

[0001] The present invention belongs to the field of carbon dioxide methane reforming, and more specifically, relates to a method and system for preparing low hydrogen-carbon ratio synthesis gas. 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.

[0003] Carbon dioxide in the petrochemical industry mainly comes from the combustion of heating furnace fuel, combustion of power station boilers and process emissions. Among the many carbon dioxide conversion and utilization technologies, carbon dioxide methane reforming to synthesis gas technology can not only make full use of 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.

[0004] Carbon dioxide methane reforming reaction equation: CH4+CO2→2CO+2H2;

[0005] From the reaction equation, it can be seen that the molar ratio of hydrogen to carbon monoxide is 1:1. At this time, hydrogen and carbon monoxide can be directly used for Fischer-Tropsch synthesis and carbonyl synthesis reactions. The carbon dioxide methane reforming reaction is a strong endothermic reaction with increased volume. Therefore, 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 for carbon dioxide and methane to be completely converted into synthesis gas.

[0006] At the same time, in the existing technology, the carbon dioxide methane reforming reaction also has the disadvantages of easy catalyst coking and deactivation, short operation cycle, high energy consumption, large pressure drop and poor adjustment flexibility.

[0007] Based on the engineering experience and professional practice gained by the inventors of the present invention in the long-term scientific research and development and engineering design in the field of hydrogen production technology, the inventors of the present invention are market-oriented and combine production, education and research to solve the shortcomings of the existing carbon dioxide methane dry reforming technology. At the same time, directly prepare low hydrogen-carbon ratio synthesis gas to meet the needs of related industrial production. After repeated research, experiments, engineering design and construction, a method for preparing low hydrogen-carbon ratio synthesis gas by methane carbon dioxide reforming with practical value was unexpectedly discovered. Summary of the invention

[0008] The purpose of the present invention is to provide a method and system for preparing synthesis gas with a low hydrogen-to-carbon ratio in view of the shortcomings of the prior art. The present invention solves the problems of easy catalyst deactivation and high energy consumption in the technology of preparing synthesis gas by reforming carbon dioxide and methane.

[0009] In order to achieve the above-mentioned object, the present invention provides a low hydrogen-to-carbon ratio synthesis gas preparation system on one hand, the system comprising a dry reforming reactor, a carbon dioxide feed pipeline, a methane feed pipeline, a compression device, a hydrogen production reaction device, a reforming raw synthesis gas processing device, and a hydrogen production synthesis gas processing device;

[0010] The dry reforming reactor is provided with a hydrogen production reaction product inlet, a reforming reaction preheating feed inlet, a hydrogen production synthesis gas outlet and a reforming crude synthesis gas outlet;

[0011] The hydrogen production reaction device comprises a radiation unit and a convection unit which are interconnected; the convection unit is provided with a plurality of groups of heat exchange coils, and the radiation unit is provided with a hydrogen production reaction product outlet; the hydrogen production reaction product outlet is connected to the hydrogen production reaction product inlet of the dry reforming reactor;

[0012] The carbon dioxide feed pipeline and the methane feed pipeline are connected to the inlet of the compression device simultaneously or separately, and the outlet of the compression device is connected to the reforming reaction preheating feed port through a heat exchange device;

[0013] The hydrogen production synthesis gas processing device comprises a hydrogen production synthesis gas heat exchanger, a steam generator, a hydrogen production reaction heat recovery unit, a shift reaction unit, a hydrogen production pressure swing adsorption unit and a hydrogen production carbon dioxide separation unit which are connected in sequence; the hydrogen production synthesis gas outlet is connected to the inlet of the hydrogen production synthesis gas heat exchanger;

[0014] The reformed crude syngas processing device comprises a reformed reaction heat recovery unit, a reformed condensate separation unit and a reformed carbon dioxide separation unit which are connected in sequence; the reformed crude syngas outlet is connected to the inlet of the reformed reaction heat recovery unit; the outlet of the reformed carbon dioxide separation unit is connected to a reformed syngas pipeline and a reformed carbon dioxide separation pipeline;

[0015] The heat exchange equipment includes at least one of the convection unit, the hydrogen production reaction heat recovery unit, the reforming reaction heat recovery unit, the hydrogen production synthesis gas heat exchanger and the steam generator.

[0016] According to the present invention, preferably, the hydrogen production reaction device comprises a convection unit, a radiation unit, a hydrodesulfurization reactor, a steam pipeline, an air pipeline and a fuel gas pipeline, and optionally further comprises a flue gas treatment unit and / or a pre-reforming reactor;

[0017] The radiation unit includes a hydrogen production conversion tube side and a hydrogen production conversion furnace shell side;

[0018] The convection unit is used to heat the hydrogen production raw material before entering the hydrogen production conversion tube side and to heat the air before entering the hydrogen production conversion shell side;

[0019] The hydrodesulfurization reactor is used to achieve desulfurization and / or hydrogenation saturation treatment of the hydrogen production raw material before it enters the hydrogen production conversion tube;

[0020] The water vapor pipeline is used to input water vapor to the hydrogen production raw material that has undergone desulfurization and / or hydrogenation saturation treatment before entering the hydrogen production conversion tube. Its functions are: first, it serves as a raw material for the reaction; second, the superheated steam can effectively avoid carbon deposition and deactivation of the hydrogen production catalyst, thereby extending the service life of the catalyst;

[0021] The air pipeline and the fuel gas pipeline are connected to the burner in the shell side of the hydrogen production reformer;

[0022] The discharge pipeline of the hydrodesulfurization reactor is connected to the inlet of the hydrogen production converter tube side, and the outlet of the hydrogen production converter tube side is the outlet of the hydrogen production reaction product;

[0023] The flue gas treatment unit comprises a flue gas pretreatment subunit and a flue gas carbon dioxide separation unit connected in sequence; the convection unit is provided with a flue gas outlet, and the flue gas outlet is connected to the flue gas pretreatment subunit; the flue gas pretreatment subunit is also connected to a smoke dust outlet pipeline; the flue gas carbon dioxide separation unit is also connected to a flue gas separation carbon dioxide outlet pipeline and a carbon dioxide-depleted flue gas outlet pipeline;

[0024] The pre-reforming reactor is used to perform pre-reforming treatment on the hydrogen production raw material after being mixed with water vapor.

[0025] In the present invention, if the hydrogen production raw material is light hydrocarbons and / or naphtha, it is necessary to set a pre-conversion reactor before the hydrogen production raw material after mixing with water vapor enters the hydrogen production converter tube process to crack large molecular hydrocarbons into small molecules such as methane and ethane, so as to avoid carbon deposition and deactivation of the hydrogen production converter tube, which is beneficial to extend the operation cycle of the hydrogen production furnace.

[0026] In the present invention, in order to extend the service life of the hydrogen production catalyst in the hydrogen production converter tube, it is necessary to desulfurize the hydrogen production feedstock or hydrogenate the unsaturated hydrocarbons in the hydrogen production feedstock to avoid carbon deposition and deactivation of the hydrogen production catalyst.

[0027] In the present invention, the convection unit provides heat for the hydrogen production raw material, air, carbon dioxide and formaldehyde, thereby further reducing the flue gas temperature at the flue gas outlet of the convection unit to achieve high energy utilization efficiency.

[0028] According to the present invention, preferably, the hydrogen production pressure swing adsorption unit is connected to a hydrogen discharge pipeline; the hydrogen production carbon dioxide separation unit is connected to a hydrogen production carbon dioxide separation pipeline and a decarbonization desorption gas pipeline.

[0029] According to the present invention, preferably, the hydrogen production carbon dioxide separation pipeline, the reforming carbon dioxide separation pipeline and the flue gas separation carbon dioxide outlet pipeline are all connected to downstream devices and / or the carbon dioxide feed pipeline at the same time.

[0030] According to the present invention, preferably, the reformed raw synthesis gas processing device also includes a reformed methane separation unit and / or a hydrogen production raw material heat exchanger; the reformed raw synthesis gas outlet, the hydrogen production raw material heat exchanger, and the inlet of the reforming reaction heat recovery unit are connected in sequence; the reformed synthetic gas pipeline is connected to the inlet of the reformed methane separation unit; the outlet of the reformed methane separation unit is connected to a reformed separation methane pipeline and a methane-lean reformed synthetic gas pipeline; the reformed separation methane pipeline is connected to at least one of the downstream device, the methane feed pipeline, the fuel gas pipeline and the hydrogen production raw material feed inlet of the hydrogen production reaction device.

[0031] According to the present invention, preferably, the heat exchange equipment includes the convection unit and the hydrogen production synthesis gas heat exchanger, and the outlet of the compression device is connected to the reforming reaction preheating feed port through the convection unit and the hydrogen production synthesis gas heat exchanger in sequence.

[0032] According to the present invention, the dry reforming reactor is a shell-and-tube reactor.

[0033] According to the present invention, preferably, the compression device comprises a carbon dioxide compressor and a methane compressor; the carbon dioxide feed pipeline is connected to the inlet of the carbon dioxide compressor; the methane feed pipeline is connected to the inlet of the methane compressor; the outlet of the carbon dioxide compressor and the outlet of the methane compressor are simultaneously or separately connected to the reforming reaction preheating feed port through a heat exchange device;

[0034] or,

[0035] The compression device is a mixed compressor; the carbon dioxide feed pipeline and the methane feed pipeline are simultaneously connected to the inlet of the mixed compressor, and the outlet of the mixed compressor is connected to the reforming reaction preheating feed port through a heat exchange device.

[0036] Another aspect of the present invention provides a method for preparing low hydrogen-to-carbon ratio synthesis gas, the method using the system comprising the following steps:

[0037] S1: After compression and heat exchange treatment, carbon dioxide and methane are sent to a dry reforming reactor to carry out a reforming reaction under the condition of a reforming catalyst; the hydrogen production reaction product from the hydrogen production reaction device is sent to a dry reforming reactor to provide heat for the reforming reaction; the dry reforming reactor obtains hydrogen production synthesis gas and reforming crude synthesis gas respectively;

[0038] S2: sequentially performing heat recovery, condensate separation and carbon dioxide separation on the reformed crude synthesis gas to obtain reformed separated carbon dioxide and reformed synthesis gas;

[0039] S3: The hydrogen production synthesis gas is sequentially subjected to heat recovery, shift reaction, pressure swing adsorption and carbon dioxide separation treatment to obtain hydrogen, hydrogen production separated carbon dioxide and decarbonization desorption gas.

[0040] In the present invention, in step S1, the hydrogen production reaction product from the hydrogen production reaction device only provides heat for the reforming reaction. As a preferred embodiment, the carbon dioxide, methane and reforming catalyst are in the tubes of the dry reforming reactor (shell-and-tube reactor), and the hydrogen production reaction product from the hydrogen production reaction device is arranged outside the tubes.

[0041] According to the present invention, preferably, the method for preparing the hydrogen production reaction product comprises:

[0042] (1) heating the hydrogen production raw material and air through the convection unit respectively;

[0043] (2) desulfurizing and / or hydrogenating the heated hydrogen production feedstock;

[0044] (3) mixing the hydrogen production feedstock that has been subjected to desulfurization and / or hydrogenation saturation treatment with steam, and optionally, subjecting the hydrogen production feedstock mixed with steam to a pre-conversion treatment;

[0045] (4) inputting fuel gas and air heated in step S1 into the burner in the shell side of the hydrogen production converter, feeding the raw material treated in step (3) into the tube side of the hydrogen production converter and carrying out a hydrogen production reaction under a hydrogen production catalyst and high temperature conditions to obtain the hydrogen production reaction product; optionally, after burning the air and fuel gas in the burner in the shell side of the hydrogen production converter, sequentially performing flue gas pretreatment and flue gas carbon dioxide separation treatment to obtain flue gas separated carbon dioxide and carbon dioxide-depleted flue gas;

[0046] Preferably, the temperature of the hydrogen production reaction is 750-950°C and the pressure is 0.5-4.0MPa;

[0047] Preferably, the hydrogen production raw material is at least one of natural gas, liquefied gas, light hydrocarbons, naphtha, refinery dry gas, low-fraction gas and coke oven gas;

[0048] Preferably, the fuel gas is at least one of natural gas, water gas, liquefied gas, refinery dry gas and low-fraction gas.

[0049] According to the present invention, preferably, the separation methods of the reforming carbon dioxide separation unit, the hydrogen production carbon dioxide separation unit and the flue gas carbon dioxide separation unit are each independently at least one of membrane separation, PSA, wet alcohol amine method, low-temperature methanol washing, low-temperature separation, hot potassium carbonate method and hydrated carbon dioxide separation method.

[0050] According to the present invention, preferably, the method further comprises sending the carbon dioxide separated by reforming, the carbon dioxide separated by hydrogen production and the carbon dioxide separated by flue gas to a downstream device and / or the carbon dioxide feed pipe.

[0051] According to the present invention, preferably, the method further comprises subjecting the reformed synthesized gas to reformed methane separation treatment to obtain reformed separated methane and methane-poor reformed synthesized gas.

[0052] According to the present invention, preferably, the processing method of reforming and separating methane includes at least one of sending to a downstream device, the methane feed pipeline, being used as fuel gas for the radiation unit, and being used as a raw material for hydrogen production.

[0053] According to the present invention, preferably, the methane content in the methane-poor reformed synthetic gas is less than 50 ppm.

[0054] According to the present invention, preferably, the separation method of the reformed methane separation unit is selected from at least one of membrane separation, PSA and cryogenic deep cooling.

[0055] According to the present invention, preferably, the reforming catalyst is selected from at least one active metal of nickel-based, rhodium-based, ruthenium-based, platinum-based, palladium-based and iridium-based; the carrier of the reforming catalyst is selected from at least one of Al2O3, SiO2, SiC, molecular sieve and TiO2; the additive of the reforming catalyst is selected from at least one of MgO, TiO2, rare earth metals and rare earth metal oxides.

[0056] In the present invention, the reforming reaction of carbon dioxide and methane is a strong endothermic reaction with increased volume. Therefore, high temperature and low pressure are conducive to the reaction. According to the present invention, preferably, the reaction temperature of the reforming reaction is 550-850°C, preferably 600-750°C, and the reaction pressure is 0.3-4.5MPa, preferably 1.0-3.5MPa; the temperature of the hydrogen production reaction product is 750-950°C, preferably 800-900°C, and the reaction pressure is 0.5-4.0MPa, preferably 1.0-3.5MPa; the molar ratio of hydrogen to carbon monoxide in the methane-poor reforming synthetic gas is 0.5:1.5-2.5:1.0, preferably 0.8:1.2-1.5:1.0. From a thermodynamic point of view, low pressure is conducive to the balance moving toward the product direction. Under the same equipment volume, the lower the pressure, the lower the yield per unit equipment volume. Therefore, under the condition of a certain equipment volume, the reaction pressure should be increased as much as possible to improve the processing capacity of the equipment.

[0057] According to the present invention, preferably, the compression heat exchange treatment includes compressing carbon dioxide and methane separately and then mixing and exchanging heat, compressing and exchanging heat of a mixture of carbon dioxide and methane, and compressing carbon dioxide and methane separately and then exchanging heat separately;

[0058] Preferably, the carbon dioxide and methane are compressed separately and then mixed for heat exchange;

[0059] The carbon dioxide is pressurized to 0.3-4.5 MPa by a carbon dioxide compressor;

[0060] The methane is pressurized to 0.3-4.5 MPa by a methane compressor;

[0061] or,

[0062] The mixed gas of carbon dioxide and methane is compressed and heat exchanged;

[0063] The mixed gas of carbon dioxide and methane is then pressurized to 0.3-4.5MPa by a mixing compressor;

[0064] The temperatures of the carbon dioxide and methane fed into the dry reforming reactor are each independently 250 to 650°C, preferably, each independently 350 to 550°C.

[0065] The beneficial effects of the technical solution of the present invention are as follows:

[0066] 1. The present invention makes full use of the high temperature heat of the hydrogen production reaction product to provide reaction heat for the methane and carbon dioxide reforming reaction, greatly improving the heat utilization efficiency of the hydrogen production reaction product. The reforming reaction of the present invention uses a catalyst with high activity at low temperature and resistance to carbon deposition deactivation, ensuring the long-term stable operation of the system.

[0067] 2. The method of preparing synthesis gas by reforming methane with carbon dioxide of the present invention can adjust the feed ratio of carbon dioxide and methane according to the composition and quality requirements of the reformed synthesis gas by downstream synthesis gas users, and has the advantages of flexible operation and meeting diverse needs.

[0068] 3. In the method for preparing synthesis gas by reforming methane with carbon dioxide of the present invention, the carbon dioxide and methane feed can be heat exchanged with the hydrogen production synthesis gas obtained in step S1, thereby increasing the feed temperature and achieving the purpose of producing less steam or no steam. In addition, the present invention can also use the heat of the high-temperature flue gas of the convection unit to increase the temperature of the carbon dioxide and methane feed, reduce the exhaust temperature of the convection unit, and further improve the energy utilization efficiency of the hydrogen production reaction device.

[0069] 4. The method for preparing synthesis gas by reforming methane with carbon dioxide of the present invention is suitable for large-scale production of synthesis gas with low H / C ratio. The whole crude synthesis gas obtained by the reforming reaction can be separated from the unconverted carbon dioxide after cooling by a heat recovery unit, and the unconverted carbon dioxide can be recycled back to the raw material inlet, thereby improving the utilization rate of carbon dioxide. The reformed synthesis gas of step S2 can be separated from the unreacted methane by a reforming methane separation unit, and the unreacted methane can be recycled back to the raw material inlet, which not only improves the utilization rate of the amount of methane, but also meets the quality requirements of the synthesis gas with low methane content or no methane content of the downstream facilities, and the product quality is stable and reliable.

[0070] 5. In the method of preparing synthesis gas by reforming methane with carbon dioxide of the present invention, the raw carbon dioxide can come from outside the device or from the system itself, such as: separating carbon dioxide by reforming, separating carbon dioxide by hydrogen production, and separating carbon dioxide by flue gas, thus achieving near-zero carbon dioxide emissions from the hydrogen production reaction device and the dry reforming reactor, with obvious environmental advantages.

[0071] 6. The method of preparing synthesis gas by reforming methane with carbon dioxide of the present invention is not only suitable for upgrading the quality and expanding the capacity of existing hydrocarbon hydrogen production equipment to increase the production of synthesis gas (hydrogen), but also suitable for newly built integrated refining and chemical projects with demand for hydrogen and low hydrogen-carbon ratio synthesis gas. The device has multiple product specifications and flexible operation.

[0072] 7. The present invention not only solves the problems of easy deactivation of catalyst and high energy consumption in the technology of preparing synthesis gas by reforming carbon dioxide and methane, but also obtains synthesis gas with a low hydrogen-to-carbon ratio, which is particularly suitable for use as a raw material for preparing methanol and ethylene glycol. The present invention can achieve the purpose of increasing the production of hydrogen (synthesis gas) without changing the existing hydrogen production furnace. As a typical method for preparing blue hydrogen, the present invention realizes the transformation of carbon dioxide into treasure, with obvious economic and environmental benefits.

[0073] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0075] Figure 1 A schematic diagram of a low hydrogen-to-carbon ratio synthesis gas preparation system provided in Example 1 of the present invention is shown.

[0076] Figure 2 A schematic diagram of a low hydrogen-to-carbon ratio synthesis gas preparation system provided in Example 2 of the present invention is shown.

[0077] Figure 3 A schematic diagram of a low hydrogen-to-carbon ratio synthesis gas preparation system provided in Example 3 of the present invention is shown.

[0078] Figure 4 A schematic diagram of a low hydrogen-to-carbon ratio synthesis gas preparation system provided in Example 4 of the present invention is shown.

[0079] The following are the descriptions of the reference numerals:

[0080] 1—convection unit, 2—radiation unit, 3—hydrodesulfurization reactor, 4—dry reforming reactor, 5—hydrogen production conversion tube side, 6—hydrogen production conversion furnace shell side, 7—hydrogen production synthesis gas heat exchanger, 8—steam generator, 9—carbon dioxide compressor, 10—methane compressor, 11—hydrogen production reaction heat recovery unit, 12—shift reaction unit, 13—hydrogen production pressure swing adsorption unit, 14—hydrogen production carbon dioxide separation unit, 15—reforming reaction heat recovery unit, 16—reforming condensate separation unit, 17—reforming carbon dioxide separation unit, 18—flue gas pretreatment subunit, 19—flue gas carbon dioxide separation unit, 20—reforming methane separation unit, 21—hydrogen production feedstock heat exchanger, 22—pre-conversion reactor;

[0081] S1—hydrogen production raw material, S2—water vapor, S3—hydrogen production reformer tube feed, S4—air, S5—fuel gas, S6—hydrogen production reaction product, S7—hydrogen production synthesis gas, S8—carbon dioxide, S9—methane, S10—reforming crude synthesis gas, S11—reforming reaction preheat feed, S12—heat exchange hydrogen production synthesis gas, S13—steam heat exchange hydrogen production synthesis gas, S14—heat recovery hydrogen production synthesis gas, S15—conversion hydrogen production synthesis gas, S16—desorption gas, S17—hydrogen, S18—hydrogen production Separation of carbon dioxide, S19—decarbonization and desorption gas, S20—heat recovery, cooling and reforming into synthetic gas, S21—reforming condensate, cooling and reforming into synthetic gas, S22—reforming into synthetic gas, S23—reforming and separation of carbon dioxide, S24—flue gas, S25—smoke dust, S26—purification of flue gas, S27—carbon dioxide-lean flue gas, S28—flue gas separation of carbon dioxide, S29—reforming and separation of methane, S30—methane-lean reforming into synthetic gas, S31—preheating of hydrogen production raw materials before heat exchange, S32—preheating of hydrogen production raw materials after heat exchange. DETAILED DESCRIPTION

[0082] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0083] Example 1

[0084] This embodiment provides a low hydrogen-to-carbon ratio synthesis gas preparation system, such as Figure 1 As shown, the system includes a dry reforming reactor 4, a carbon dioxide feed pipeline, a methane feed pipeline, a compression device, a hydrogen production reaction device, a reforming raw synthesis gas processing device, and a hydrogen production synthesis gas processing device;

[0085] The dry reforming reactor 4 is a shell-and-tube reactor, and is provided with a hydrogen production reaction product inlet, a reforming reaction preheating feed inlet, a hydrogen production synthesis gas outlet, and a reforming crude synthesis gas outlet;

[0086] The hydrogen production reaction device comprises a convection unit 1 and a radiation unit 2 which are interconnected, as well as a hydrodesulfurization reactor 3, a water vapor pipeline, an air pipeline and a fuel gas pipeline;

[0087] The convection unit 1 is provided with a plurality of groups of heat exchange coils for heating the hydrogen production raw material S1 before entering the hydrogen production conversion tube side and heating the air S4 before entering the hydrogen production conversion shell side;

[0088] The radiation unit 2 includes a hydrogen production conversion tube side 5 and a hydrogen production conversion furnace shell side 6, and is provided with a hydrogen production reaction product outlet;

[0089] The hydrodesulfurization reactor 3 is used to achieve desulfurization treatment of the hydrogen production raw material S1 before entering the hydrogen production conversion tube 5;

[0090] The water vapor pipeline is used to input water vapor to the hydrogen production raw material that has undergone desulfurization treatment before entering the hydrogen production conversion tube 5;

[0091] The air pipeline and the fuel gas pipeline are connected to the burner in the shell side 6 of the hydrogen production reformer;

[0092] The discharge pipeline of the hydrodesulfurization reactor 3 is connected to the inlet of the hydrogen production converter tube 5, and the outlet of the hydrogen production converter tube 5 is the outlet of the hydrogen production reaction product;

[0093] The hydrogen production reaction product outlet is connected to the hydrogen production reaction product inlet of the dry reforming reactor;

[0094] The compression device comprises a carbon dioxide compressor 9 and a methane compressor 10; the carbon dioxide feed pipeline is connected to the inlet of the carbon dioxide compressor 9; the methane feed pipeline is connected to the inlet of the methane compressor 10; the outlet of the carbon dioxide compressor 9 and the outlet of the methane compressor 10 are simultaneously connected to the reforming reaction preheating feed port through the hydrogen production synthesis gas heat exchanger 7;

[0095] The hydrogen production synthesis gas processing device comprises the hydrogen production synthesis gas heat exchanger 7, the steam generator 8, the hydrogen production reaction heat recovery unit 11, the shift reaction unit 12, the hydrogen production pressure swing adsorption unit 13 and the hydrogen production carbon dioxide separation unit 14 which are connected in sequence; the hydrogen production synthesis gas outlet is connected to the inlet of the hydrogen production synthesis gas heat exchanger 7; the hydrogen production pressure swing adsorption unit 13 is connected to the hydrogen discharge pipeline; the hydrogen production carbon dioxide separation unit is connected to the hydrogen production carbon dioxide separation pipeline and the decarbonization desorption gas pipeline;

[0096] The reformed crude synthesis gas processing device comprises a reforming reaction heat recovery unit 15, a reforming condensate separation unit 16, a reforming carbon dioxide separation unit 17 and a reforming methane separation unit 20 which are connected in sequence; the reformed crude synthesis gas outlet is connected to the inlet of the reforming reaction heat recovery unit 15; the outlet of the reforming carbon dioxide separation unit 17 is connected to a reforming synthesis gas pipeline and a reforming separation carbon dioxide pipeline; the reforming synthesis gas pipeline is connected to the inlet of the reforming methane separation unit 20; the outlet of the reforming methane separation unit 20 is connected to a reforming separation methane pipeline and a methane-poor reforming synthesis gas pipeline;

[0097] In this embodiment, the preparation of low hydrogen-to-carbon ratio synthesis gas using the above system includes the following steps:

[0098] S1: After compression and heat exchange treatment, carbon dioxide S8 and methane S9 are pressurized to 2.55MPa, heat exchanged to 450°C, and sent into the tube of a dry reforming reactor to carry out a reforming reaction under the conditions of a reforming catalyst (nickel-based-ruthenium-based, with a carrier of Al2O3); the hydrogen production reaction product S6 from the hydrogen production reaction device is sent into a dry reforming reactor to provide heat for the reforming reaction; the dry reforming reactor obtains hydrogen production synthesis gas S7 (temperature of 710°C, pressure of 3.15MPa) and reforming crude synthesis gas S10;

[0099] The reaction temperature of the reforming reaction is 600-680°C and the reaction pressure is 2.5MPa;

[0100] The method for preparing the hydrogen production reaction product comprises:

[0101] (1) The hydrogen production raw material S1 natural gas and the air S4 are respectively heated through the convection unit 1;

[0102] (2) desulfurizing the heated hydrogen production raw material;

[0103] (3) mixing the desulfurized hydrogen production raw material with water vapor S2;

[0104] (4) inputting fuel gas (natural gas and decarbonized desorbed gas from a hydrogen production carbon dioxide separation unit) and the air heated in step S1 into the burner in the shell side of the hydrogen production converter, feeding the raw material treated in step (3) into the tube side of the hydrogen production converter and carrying out a hydrogen production reaction under a hydrogen production catalyst and high temperature conditions to obtain the hydrogen production reaction product S6, the temperature of which is 850° C. and the pressure of which is 3.2 MPa;

[0105] S2: The reformed crude synthesis gas S10 is sequentially subjected to heat recovery, condensate separation and carbon dioxide separation treatment to obtain reformed separated carbon dioxide S23 and reformed synthetic gas S22; the reformed separated carbon dioxide S23 is sent to a downstream device; the reformed synthetic gas S22 is subjected to reformed methane separation treatment to obtain reformed separated methane S29 and a methane-poor reformed synthetic gas S30; the methane content in the methane-poor reformed synthetic gas S30 is less than 50 ppm; the molar ratio of hydrogen to carbon monoxide in the methane-poor reformed synthetic gas S30 is 1.0:1.0; the reformed separated methane S29 is sent to a downstream device;

[0106] S3: The hydrogen production synthesis gas S7 is sequentially subjected to heat recovery, shift reaction, pressure swing adsorption and carbon dioxide separation treatment to obtain hydrogen S17, hydrogen production separation carbon dioxide S18 and decarbonization desorption gas S19. The hydrogen production separation carbon dioxide S18 is sent to a downstream device.

[0107] The separation methods of the reforming carbon dioxide separation unit 17 and the hydrogen production carbon dioxide separation unit 14 are each independently PSA;

[0108] The separation method of the reforming methane separation unit 20 is cryogenic deep cooling.

[0109] Example 2

[0110] This embodiment provides a low hydrogen-to-carbon ratio synthesis gas preparation system, such as Figure 2 As shown, the difference between this embodiment and embodiment 1 is only that:

[0111] The hydrogen production raw material contains 0.5% (mol) of C3-C4 components, so the hydrogen production reaction device also includes a pre-conversion reactor 22; the pre-conversion reactor 22 is used to perform pre-conversion treatment on the hydrogen production raw material after mixing with water vapor, cracking large molecular hydrocarbons into small molecules such as methane and ethane, avoiding carbon deposition and deactivation of the hydrogen production converter tube, which is beneficial to extending the operation cycle of the hydrogen production furnace.

[0112] Example 3

[0113] This embodiment provides a low hydrogen-to-carbon ratio synthesis gas preparation system, such as Figure 3 As shown, the difference between this embodiment and embodiment 1 is only that:

[0114] The outlet of the carbon dioxide compressor 9 and the outlet of the methane compressor 10 are simultaneously connected to the reforming reaction preheating feed port through the convection unit 1 and the hydrogen production synthesis gas heat exchanger 7 in sequence;

[0115] The reformed crude syngas processing device comprises a reforming reaction heat recovery unit 15, a reforming condensate separation unit 16, and a reforming carbon dioxide separation unit 17 which are connected in sequence; the reformed crude syngas outlet is connected to the inlet of the reforming reaction heat recovery unit 15; the outlet of the reforming carbon dioxide separation unit 17 is connected to a reforming syngas pipeline and a reforming carbon dioxide separation pipeline;

[0116] The hydrogen production reaction device also includes a flue gas treatment unit, which includes a flue gas pretreatment subunit 18 and a flue gas carbon dioxide separation unit 19 connected in sequence; the convection unit 1 is provided with a flue gas outlet, which is connected to the flue gas pretreatment subunit 18; the flue gas pretreatment subunit 18 is also connected to a smoke dust outlet pipeline; the flue gas carbon dioxide separation unit is also connected to a flue gas separation carbon dioxide outlet pipeline and a carbon dioxide-depleted flue gas outlet pipeline;

[0117] The hydrogen production carbon dioxide separation pipeline, the reforming carbon dioxide separation pipeline and the flue gas separation carbon dioxide outlet pipeline are all connected to the carbon dioxide feed pipeline at the same time;

[0118] This embodiment adopts the above system to prepare low hydrogen-to-carbon ratio synthesis gas, which differs from the embodiment 1 only in that:

[0119] S1: After compression, the carbon dioxide S8 and methane S9 are pressurized to 2.55 MPa respectively, heat exchanged to 230° C. by the convection unit 1, and then heat exchanged to 490° C. by the hydrogen production synthesis gas heat exchanger 7.

[0120] After burning the air S4 and the fuel gas S5 in the burner in the shell side 6 of the hydrogen production reformer, flue gas pretreatment and flue gas carbon dioxide separation treatment are performed in sequence to obtain flue gas separated carbon dioxide S28 and carbon dioxide-depleted flue gas S27; the separation method of the flue gas carbon dioxide separation unit is PSA;

[0121] S2: The reformed crude synthesis gas is subjected to heat recovery, condensate separation and carbon dioxide separation treatment in sequence to obtain reformed separated carbon dioxide S23 and reformed synthetic gas S22; the molar ratio of hydrogen to carbon monoxide in the reformed synthetic gas S22 is 1.0:0.98; the reformed separated carbon dioxide S23, hydrogen production separated carbon dioxide S18 and flue gas separated carbon dioxide S28 are fed into the carbon dioxide feed pipe.

[0122] Example 4

[0123] This embodiment provides a low hydrogen-to-carbon ratio synthesis gas preparation system, such as Figure 4 As shown, the difference between this embodiment and embodiment 1 is only that:

[0124] The reformed crude synthesis gas processing device further includes a hydrogen production raw material heat exchanger 21; the reformed crude synthesis gas outlet, the hydrogen production raw material heat exchanger 21, and the inlet of the reforming reaction heat recovery unit 15 are connected in sequence;

[0125] After the hydrogen production raw material S1 is heated by the convection unit 1, it is heat-exchanged with the gas at the outlet of the reformed raw synthesis gas before being desulfurized.

[0126] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A low hydrogen-to-carbon ratio synthesis gas preparation system, characterized in that: The system includes a dry reforming reactor, a carbon dioxide feed pipeline, a methane feed pipeline, a compression device, a hydrogen production reaction device, a reforming raw synthesis gas processing device, and a hydrogen production synthesis gas processing device; The dry reforming reactor is provided with a hydrogen production reaction product inlet, a reforming reaction preheating feed inlet, a hydrogen production synthesis gas outlet and a reforming crude synthesis gas outlet; The hydrogen production reaction device comprises a radiation unit and a convection unit which are interconnected; the convection unit is provided with a plurality of groups of heat exchange coils, and the radiation unit is provided with a hydrogen production reaction product outlet; the hydrogen production reaction product outlet is connected to the hydrogen production reaction product inlet of the dry reforming reactor; The carbon dioxide feed pipeline and the methane feed pipeline are connected to the inlet of the compression device simultaneously or separately, and the outlet of the compression device is connected to the reforming reaction preheating feed port through a heat exchange device; The hydrogen production synthesis gas processing device comprises a hydrogen production synthesis gas heat exchanger, a steam generator, a hydrogen production reaction heat recovery unit, a shift reaction unit, a hydrogen production pressure swing adsorption unit and a hydrogen production carbon dioxide separation unit which are connected in sequence; the hydrogen production synthesis gas outlet is connected to the inlet of the hydrogen production synthesis gas heat exchanger; The reformed crude syngas processing device comprises a reformed reaction heat recovery unit, a reformed condensate separation unit and a reformed carbon dioxide separation unit which are connected in sequence; the reformed crude syngas outlet is connected to the inlet of the reformed reaction heat recovery unit; the outlet of the reformed carbon dioxide separation unit is connected to a reformed syngas pipeline and a reformed carbon dioxide separation pipeline; The heat exchange equipment includes at least one of the convection unit, the hydrogen production reaction heat recovery unit, the reforming reaction heat recovery unit, the hydrogen production synthesis gas heat exchanger and the steam generator.

2. The low hydrogen-to-carbon ratio synthesis gas production system according to claim 1, wherein: The hydrogen production reaction device comprises a convection unit, a radiation unit, a hydrodesulfurization reactor, a steam pipeline, an air pipeline and a fuel gas pipeline, and optionally further comprises a flue gas treatment unit and / or a pre-reforming reactor; The radiation unit includes a hydrogen production conversion tube side and a hydrogen production conversion furnace shell side; The convection unit is used to heat the hydrogen production raw material before entering the hydrogen production conversion tube side and to heat the air before entering the hydrogen production conversion shell side; The hydrodesulfurization reactor is used to achieve desulfurization and / or hydrogenation saturation treatment of the hydrogen production raw material before it enters the hydrogen production conversion tube; The water vapor pipeline is used to input water vapor to the hydrogen production raw material that has undergone desulfurization and / or hydrogenation saturation treatment before entering the hydrogen production conversion tube process; The air pipeline and the fuel gas pipeline are connected to the burner in the shell side of the hydrogen production reformer; The discharge pipeline of the hydrodesulfurization reactor is connected to the inlet of the hydrogen production converter tube side, and the outlet of the hydrogen production converter tube side is the outlet of the hydrogen production reaction product; The flue gas treatment unit comprises a flue gas pretreatment subunit and a flue gas carbon dioxide separation unit connected in sequence; the convection unit is provided with a flue gas outlet, and the flue gas outlet is connected to the flue gas pretreatment subunit; the flue gas pretreatment subunit is also connected to a smoke dust outlet pipeline; the flue gas carbon dioxide separation unit is also connected to a flue gas separation carbon dioxide outlet pipeline and a carbon dioxide-depleted flue gas outlet pipeline; The pre-reforming reactor is used to perform pre-reforming treatment on the hydrogen production raw material after being mixed with water vapor.

3. The low hydrogen-to-carbon ratio synthesis gas production system according to claim 2, wherein: The hydrogen production pressure swing adsorption unit is connected to a hydrogen discharge pipeline; the hydrogen production carbon dioxide separation unit is connected to a hydrogen production carbon dioxide separation pipeline and a decarbonization desorption gas pipeline; The hydrogen production carbon dioxide separation pipeline, the reforming carbon dioxide separation pipeline and the flue gas separation carbon dioxide outlet pipeline are all connected to the downstream device and / or the carbon dioxide feed pipeline at the same time; The reformed raw synthesis gas processing device also includes a reformed methane separation unit and / or a hydrogen production raw material heat exchanger; the reformed raw synthesis gas outlet, the hydrogen production raw material heat exchanger, and the inlet of the reforming reaction heat recovery unit are connected in sequence; the reformed synthesis gas pipeline is connected to the inlet of the reformed methane separation unit; the outlet of the reformed methane separation unit is connected to a reformed separation methane pipeline and a methane-poor reformed synthesis gas pipeline; the reformed separation methane pipeline is connected to at least one of a downstream device, the methane feed pipeline, a fuel gas pipeline, and a hydrogen production raw material feed port of the hydrogen production reaction device; The heat exchange equipment includes the convection unit and the hydrogen production synthesis gas heat exchanger, and the outlet of the compression device is connected to the reforming reaction preheating feed port through the convection unit and the hydrogen production synthesis gas heat exchanger in sequence; The dry reforming reactor is a shell-and-tube reactor.

4. The low hydrogen-to-carbon ratio synthesis gas production system according to claim 1, wherein: The compression device comprises a carbon dioxide compressor and a methane compressor; the carbon dioxide feed pipeline is connected to the inlet of the carbon dioxide compressor; the methane feed pipeline is connected to the inlet of the methane compressor; the outlet of the carbon dioxide compressor and the outlet of the methane compressor are simultaneously or separately connected to the reforming reaction preheating feed port through a heat exchange device; or, The compression device is a mixed compressor; the carbon dioxide feed pipeline and the methane feed pipeline are simultaneously connected to the inlet of the mixed compressor, and the outlet of the mixed compressor is connected to the reforming reaction preheating feed port through a heat exchange device.

5. A method for preparing low hydrogen-to-carbon ratio synthesis gas, characterized in that: The method adopts the system according to any one of claims 1 to 4, comprising the following steps: S1: After compression and heat exchange treatment, carbon dioxide and methane are sent to a dry reforming reactor to carry out a reforming reaction under the condition of a reforming catalyst; the hydrogen production reaction product from the hydrogen production reaction device is sent to a dry reforming reactor to provide heat for the reforming reaction; the dry reforming reactor obtains hydrogen production synthesis gas and reforming crude synthesis gas respectively; S2: sequentially performing heat recovery, condensate separation and carbon dioxide separation on the reformed crude synthesis gas to obtain reformed separated carbon dioxide and reformed synthesis gas; S3: The hydrogen production synthesis gas is sequentially subjected to heat recovery, shift reaction, pressure swing adsorption and carbon dioxide separation treatment to obtain hydrogen, hydrogen production separated carbon dioxide and decarbonization desorption gas.

6. The method for preparing low hydrogen-to-carbon ratio synthesis gas according to claim 5, wherein: The method for preparing the hydrogen production reaction product comprises: (1) heating the hydrogen production raw material and air through the convection unit respectively; (2) desulfurizing and / or hydrogenating the heated hydrogen production feedstock; (3) mixing the hydrogen production feedstock that has been subjected to desulfurization and / or hydrogenation saturation treatment with steam, and optionally, subjecting the hydrogen production feedstock mixed with steam to a pre-conversion treatment; (4) inputting fuel gas and air heated in step S1 into the burner in the shell side of the hydrogen production converter, feeding the raw material treated in step (3) into the tube side of the hydrogen production converter and carrying out a hydrogen production reaction under a hydrogen production catalyst and high temperature conditions to obtain the hydrogen production reaction product; optionally, after burning the air and fuel gas in the burner in the shell side of the hydrogen production converter, sequentially performing flue gas pretreatment and flue gas carbon dioxide separation treatment to obtain flue gas separated carbon dioxide and carbon dioxide-depleted flue gas; Preferably, the temperature of the hydrogen production reaction is 750-950°C and the pressure is 0.5-4.0MPa; Preferably, the hydrogen production raw material is at least one of natural gas, liquefied gas, light hydrocarbons, naphtha, refinery dry gas, low-fraction gas and coke oven gas; Preferably, the fuel gas is at least one of natural gas, water gas, liquefied gas, refinery dry gas and low-fraction gas.

7. The method for preparing low hydrogen-to-carbon ratio synthesis gas according to claim 6, wherein: The separation methods of the reforming carbon dioxide separation unit, the hydrogen production carbon dioxide separation unit and the flue gas carbon dioxide separation unit are each independently at least one of membrane separation, PSA, wet alcohol amine method, low-temperature methanol washing, low-temperature separation, hot potassium carbonate method and hydrated carbon dioxide separation method; The method further comprises sending the carbon dioxide separated by reforming, the carbon dioxide separated by hydrogen production and the carbon dioxide separated by flue gas to a downstream device and / or the carbon dioxide feed pipe.

8. The method for preparing low hydrogen-to-carbon ratio synthesis gas according to claim 6, wherein: The method further comprises subjecting the reformed synthesized gas to reformed methane separation treatment to obtain reformed separated methane and methane-poor reformed synthesized gas; The processing method of reforming separated methane includes sending it to a downstream device, the methane feed pipeline, using it as fuel gas for the radiation unit, and using it as at least one of a raw material for hydrogen production; The methane content in the methane-poor reformed synthetic gas is less than 50 ppm; Preferably, the separation method of the reformed methane separation unit is selected from at least one of membrane separation, PSA and cryogenic deep cooling.

9. The method for preparing low hydrogen-to-carbon ratio synthesis gas according to claim 5, wherein: The reforming catalyst is selected from at least one active metal of nickel-based, rhodium-based, ruthenium-based, platinum-based, palladium-based and iridium-based; the carrier of the reforming catalyst is selected from at least one of Al2O3, SiO2, SiC, molecular sieve and TiO2; the promoter of the reforming catalyst is selected from at least one of MgO, TiO2, rare earth metals and rare earth metal oxides; The reaction temperature of the reforming reaction is 550-850°C, preferably 600-750°C, and the reaction pressure is 0.3-4.5MPa, preferably 1.0-3.5MPa; the temperature of the hydrogen production reaction product is 750-950°C, preferably 800-900°C, and the reaction pressure is 0.5-4.0MPa, preferably 1.0-3.5MPa; the molar ratio of hydrogen to carbon monoxide in the methane-poor reforming synthetic gas is 0.5:1.5-2.5:1.

0.

10. The method for preparing low hydrogen-to-carbon ratio synthesis gas according to claim 5, wherein: The compression heat exchange treatment includes compressing carbon dioxide and methane separately and then mixing and exchanging heat, compressing and exchanging heat of a mixture of carbon dioxide and methane, and compressing carbon dioxide and methane separately and then exchanging heat separately; Preferably, the carbon dioxide and methane are compressed separately and then mixed for heat exchange; The carbon dioxide is pressurized to 0.3-4.5 MPa by a carbon dioxide compressor; The methane is pressurized to 0.3-4.5 MPa by a methane compressor; or, The mixed gas of carbon dioxide and methane is compressed and heat exchanged; The mixed gas of carbon dioxide and methane is then pressurized to 0.3-4.5MPa by a mixing compressor; The temperatures of the carbon dioxide and methane fed into the dry reforming reactor are each independently 250 to 650°C, preferably, each independently 350 to 550°C.

Images