Method for preparing synthesis gas

Abstract

The invention relates to a method for preparing synthesis gas, and the method comprises the following steps: carrying out first heating on a hydrogen production raw material, and sequentially feeding the hydrogen production raw material into a hydrogenation reactor and a hydrodesulfurization reactor to obtain a desulfurized hydrogen production raw material; and mixing the desulfurized hydrogen production raw material, water vapor and a carbon dioxide raw material, carrying out second heating to obtain a mixed raw material, feeding the mixed raw material into a radiation unit of a hydrogen production converter, carrying out a catalytic reforming reaction with a reforming catalyst to obtain a reformed crude synthesis gas, and carrying out heat exchange on the reformed crude synthesis gas and part of the carbon dioxide raw material. According to the invention, the reaction for preparing the synthesis gas by reforming is carried out in the hydrogen production reformer, and the problems of easy carbon deposition and short operation period of the reforming reaction in industrial production are solved by utilizing a high-temperature and water-vapor-containing environment in the hydrogen production reformer; the prepared high-temperature reformed crude synthesis gas exchanges heat with a carbon dioxide raw material, the feeding temperature is increased, the energy utilization efficiency of the hydrogen production reformer is improved, meanwhile, carbon dioxide is recycled, and near-zero emission of carbon dioxide is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of preparing synthesis gas, and in particular relates to a method for preparing synthesis gas. Background Art

[0002] The refining 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 refining industry mainly comes from heating furnace fuel combustion, power station boiler combustion and process emissions. Among them, coal-to-hydrogen and natural gas hydrogen production devices also produce a large amount of carbon dioxide emissions. Under high temperature and water vapor conditions, the natural gas hydrogen production device undergoes a natural gas steam reforming reaction, and the generated CO undergoes a water-gas shift reaction to obtain hydrogen and carbon dioxide, and the carbon dioxide is directly discharged into the atmosphere. In the prior art, the high-temperature heat at the outlet of the hydrogen production furnace directly produces 3.5MPa steam, which is sent to downstream equipment after the temperature drops below 400°C. Among the many carbon dioxide conversion and utilization technologies, carbon dioxide methane reforming to produce synthesis gas and carbon dioxide reverse water-gas shift reaction 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 have received great attention from academia and industry.

[0003] CO2-methane reforming reaction: CH 4 +CO 2 →2CO+2H 2

[0004] Reverse water gas shift reaction: H 2 +CO 2 →CO+H 2 O

[0005] In the CO2-methane dry reforming reaction, 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 for CO2 and methane to be completely converted into synthesis gas. In addition, the reverse water-gas shift is also an endothermic reaction, and high temperature conditions are conducive to the reaction.

[0006] Most of the existing methods for preparing synthesis gas have the disadvantages of catalysts being easily coked and deactivated, carbon deposits being easily formed in industrial production, and having a short operation cycle. At the same time, the complete conversion of carbon dioxide and methane into synthesis gas requires a high reaction temperature, high energy consumption, large pressure drop, and poor adjustment flexibility.

[0007] How to efficiently utilize the high temperature conditions or high temperature heat of the hydrogen production device, while achieving energy conservation and emission reduction of carbon dioxide in the hydrogen production device, turning waste into treasure, and preparing high-value chemical products, is a technical problem that urgently needs to be solved in the current field of hydrogen production technology. Summary of the invention

[0008] The purpose of the present disclosure is to provide a method for preparing synthesis gas. The method of the present invention carries out the reforming reaction of hydrogen production raw materials and carbon dioxide in a hydrogen production converter, making full use of the high temperature and water vapor-containing environment in the furnace tube of the hydrogen production converter to solve the problems of easy carbon deposition and short operation cycle of the reforming reaction in industrial production; on the other hand, the high-temperature reformed crude synthesis gas prepared by the hydrogen production converter is used for heat exchange with the carbon dioxide raw material, thereby increasing the feed temperature, so that almost no high-temperature steam is generated in the preparation process, thereby improving the energy utilization efficiency of the hydrogen production converter, and at the same time the carbon dioxide raw material is recycled to achieve near-zero carbon dioxide emissions in the device.

[0009] In order to achieve the above object, the present invention provides a method for preparing synthesis gas, wherein the method comprises:

[0010] a. sending the hydrogen production raw material to a hydrogenation reactor and a hydrodesulfurization reactor in sequence after the first heating to obtain a desulfurized hydrogen production raw material;

[0011] b. mixing the desulfurized hydrogen production feedstock, water vapor and carbon dioxide feedstock and performing a second heating to obtain a mixed feedstock, sending the mixed feedstock to a radiation unit of a hydrogen production converter to contact with a reforming catalyst to perform a catalytic reforming reaction, obtaining a reformed crude synthesis gas from an outlet of the radiation unit of the hydrogen production converter, and cooling the reformed crude synthesis gas through a steam generator to obtain a first synthesis gas;

[0012] c. optionally sending the first synthesis gas into a shift reactor for a shift reaction to obtain a first shifted gas; sending the first shifted gas into a heat exchanger for heat exchange to obtain a second shifted gas; wherein, before entering the radiation unit, at least part of the carbon dioxide feedstock is allowed to enter the heat exchanger for heat exchange with the first synthesis gas; or

[0013] c' using the first synthesis gas as a deoxygenation heat source for a deaerator.

[0014] Optionally, the method further comprises:

[0015] d. separating carbon dioxide from the second shifted gas to obtain a reformed synthesis gas; sending the carbon dioxide to the heat exchanger to exchange heat with the first synthesis gas, and then using the carbon dioxide as the carbon dioxide raw material;

[0016] The separation method 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; preferably, the separation includes sending the second conversion gas into a carbon dioxide absorption tower to contact with an absorption liquid to obtain the recombined synthetic gas and rich liquid, sending the rich liquid into a carbon dioxide desorption tower for desorption to obtain the carbon dioxide and regenerated absorption liquid, and returning the regenerated absorption liquid to the carbon dioxide absorption tower for recycling;

[0017] Optionally, the method further comprises: before entering the carbon dioxide absorption tower, allowing the second shifted gas to enter a cooler for cooling, and then enter a liquid separator tank, and the separated tank top gas phase enters the carbon dioxide absorption tower.

[0018] Optionally, the method further comprises: 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 mixing it with the carbon dioxide raw material and sending it to the radiation unit after a third heating.

[0019] Optionally, the method further comprises:

[0020] The flue gas of the hydrogen production reformer is sent to a dust collector, a flue gas carbon dioxide absorption tower and a flue gas carbon dioxide desorption tower to separate carbon dioxide, thereby obtaining carbon dioxide-lean flue gas and carbon dioxide separated from the flue gas of the hydrogen production reformer;

[0021] The carbon dioxide raw material also includes carbon dioxide separated from flue gas of hydrogen production converter and;

[0022] Optionally, the carbon dioxide feedstock also includes carbon dioxide supplemented from outside the device.

[0023] Optionally, the method further comprises: before entering the radiation unit, pressurizing the carbon dioxide raw material to 0.35-7.0 MPa via a carbon dioxide compressor; the carbon dioxide compressor is selected from one or more of a reciprocating compressor, a centrifugal compressor and a screw compressor.

[0024] Optionally, the method further includes: a by-line is provided at the inlet of the shift reactor, and the intake amount of the first synthesis gas is controlled by adjusting a by-line valve, and the proportion of the first synthesis gas entering the shift reactor to the total amount of the first synthesis gas is 0 to 100%.

[0025] Optionally, the shift reactor is one or more of a shell-and-tube reactor, a fixed bed reactor, a radial bed reactor and an axial radial reactor;

[0026] The conditions of the shift reaction include: a reaction temperature of 120 to 500° C. and a reaction pressure of 0.3 to 6.4 MPa.

[0027] Optionally, the sulfur content of the hydrogen production raw material is 0 to 1000 ppm, and the C 3 -C 4 The hydrocarbon content is 0 to 10 mol%;

[0028] 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;

[0029] The first temperature increase, the second temperature increase and the third temperature increase are performed in the radiation unit of the hydrogen production converter and / or through heat exchange of the reforming reaction product stream;

[0030] The reaction temperature of the hydrogenation reactor is 220-450°C, and the reaction temperature of the hydrodesulfurization reactor is 220-430°C.

[0031] Optionally, the conditions of the catalytic reforming reaction include: a reaction temperature of 550 to 950° C., a reaction pressure of 0.3 to 6.5 MPa, a temperature of the reformed crude synthesis gas of 550 to 950° C., and a pressure of 0.3 to 6.4 MPa;

[0032] The hydrogen production converter furnace tube is filled with a reforming reaction catalyst; the reforming catalyst comprises a reforming catalytic active component and an auxiliary agent, 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 Al 2 O 3 、SiO 2 , SiC, molecular sieve, TiO 2 , MgO, rare earth metals and rare earth metal oxides.

[0033] Optionally, the molar ratio of hydrogen to carbon monoxide in the crude synthesis gas is (0.2-3.0):1;

[0034] The content of methane in the reformed synthetic gas is less than 150 ppm, and the content of carbon dioxide is less than 300 ppm; the molar ratio of hydrogen to carbon monoxide in the reformed synthetic gas is (0.5-3.5):1.

[0035] Through the above technical scheme, the preparation method of the present invention places the reaction of hydrogen production raw materials and carbon dioxide reforming to produce synthesis gas in a hydrogen production converter. On the basis of not changing the existing hydrogen production converter, the high temperature and water vapor-containing environment in the furnace tube of the hydrogen production converter are fully utilized to solve the problems of easy carbon deposition and short operation cycle of the reforming reaction in industrial production, and at the same time obtain high value-added reformed synthesis gas; on the other hand, the high-temperature reformed crude synthesis gas prepared by the hydrogen production converter is used for heat exchange with the carbon dioxide raw material, thereby increasing the feed temperature, so that almost no high-temperature steam is generated in the preparation process, which significantly improves the heat utilization efficiency of the hydrogen production converter, reduces the process energy consumption and preparation cost of reforming synthesis gas, and at the same time, the carbon dioxide raw material is recycled in the preparation process to achieve near-zero carbon dioxide emissions, which has obvious environmental advantages.

[0036] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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:

[0038] Figure 1 This is a schematic block diagram of the process flow of Example 1 of the present invention.

[0039] Figure 2 This is a schematic block diagram of the process flow of Example 2 of the present invention.

[0040] Figure 3 This is a schematic block diagram of the process flow of Example 3 of the present invention.

[0041] Figure 4 It is a schematic block diagram of the process flow of Example 4 and Example 5 of the present invention.

[0042] Figure 5 This is a schematic block diagram of the process flow of Example 6 of the present invention.

[0043] Figure 6 This is a schematic block diagram of the process flow of Example 7 of the present invention.

[0044] Figure 7 This is a schematic diagram of the process flow of Example 1 of the present invention.

[0045] Figure 8 This is a schematic diagram of the process flow of Example 2 of the present invention.

[0046] Fig. 9 This is a schematic diagram of the process flow of Example 3 of the present invention.

[0047] Fig.10This is a schematic diagram of the process flow of Example 4 of the present invention.

[0048] Fig.11 This is a schematic diagram of the process flow of Example 5 of the present invention.

[0049] Fig.12 This is a schematic diagram of the process flow of Example 6 of the present invention.

[0050] Fig.13 This is a schematic diagram of the process flow of Example 7 of the present invention.

[0051] Description of Reference Numerals

[0052] A1, hydrodesulfurization unit; A2, convection unit; A3, radiation unit; A4, steam generation unit; A5, heat exchange unit; A6, carbon dioxide separation unit; A7, carbon dioxide boosting unit; A8, flue gas pretreatment unit; A9, flue gas carbon dioxide recovery unit; A10, pre-conversion unit.

[0053] 1. Convection unit of hydrogen production reformer; 2. Radiation unit; 3. Hydrodesulfurization reactor; 4. Steam generator; 5. Hydrogenation reactor; 6. Shift reactor; 7. Heat exchanger; 8. Cooler; 9. Separation tank; 10. Carbon dioxide compressor; 11. Carbon dioxide absorption tower; 12. Carbon dioxide desorption tower; 13. Dust collector; 14. Flue gas carbon dioxide absorption tower; 15. Flue gas carbon dioxide desorption tower; 16. Pre-conversion reactor; 17. Deaerator.

[0054] S1, hydrogen production raw material; S2, steam; S3, radiation unit feed; S4, air; S5, fuel gas; S6, reformed raw synthesis gas; S7, first synthesis gas; S8, first shift gas; S9, second shift gas;

[0055] S10, the third conversion gas; S11, condensate; S12, tank top gas phase; S13, carbon dioxide separated from the tank top gas phase; S14, carbon dioxide supplemented outside the device; S15, pressurized carbon dioxide; S16, the first heated carbon dioxide; S17, carbon dioxide raw material; S18, dust-removed flue gas; S19, carbon dioxide-lean flue gas; S20, carbon dioxide separated from flue gas; S21, flue gas; S22, re-integrated synthetic gas; S23, desalted water; S24, heated desalted water. DETAILED DESCRIPTION

[0056] 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.

[0057] like Figure 7 As shown, the present invention provides a method for preparing synthesis gas, wherein the method comprises:

[0058] a. sending the hydrogen production raw material S1 to the hydrogenation reactor 5 and the hydrodesulfurization reactor 3 in sequence after the first heating to obtain the desulfurized hydrogen production raw material;

[0059] b. Mixing the desulfurized hydrogen production raw material, water vapor S2 and carbon dioxide raw material S17 and performing a second heating to obtain a mixed raw material, sending the mixed raw material to the radiation unit 2 of the hydrogen production converter to contact with the reforming catalyst to perform a catalytic reforming reaction, and obtaining a reformed crude synthesis gas S6 from the outlet of the radiation unit 2 of the hydrogen production converter, and cooling the reformed crude synthesis gas S6 through the steam generator 4 to obtain a first synthesis gas S7;

[0060] c. optionally sending the first synthesis gas S7 into a shift reactor 6 for a shift reaction to obtain a first shifted gas S8; sending the first shifted gas S8 into a heat exchanger 7 for heat exchange to obtain a second shifted gas S9; wherein, before entering the radiation unit 2, at least a portion of the carbon dioxide feedstock S17 enters the heat exchanger 7 for heat exchange with the first synthesis gas S7; or

[0061] like Fig.13 As shown, c' uses the first synthesis gas S7 as a deoxygenation heat source for the deaerator.

[0062] The preparation method of the present invention places the reaction of hydrogen production raw materials and carbon dioxide reforming to produce synthesis gas in a hydrogen production converter. On the basis of not changing the existing hydrogen production converter, it fully utilizes the high temperature and water vapor-containing environment in the furnace tube of the hydrogen production converter to solve the problems of easy carbon deposition and short operation cycle of the reforming reaction in industrial production; on the other hand, the high-temperature reformed crude synthesis gas prepared by the hydrogen production converter is used for heat exchange with the carbon dioxide raw material, thereby increasing the feed temperature, so that almost no high-temperature steam is generated in the preparation process, which significantly improves the heat utilization efficiency of the hydrogen production converter, reduces the process energy consumption and preparation cost of reforming synthesis gas, and at the same time, the carbon dioxide raw material is recycled in the preparation process to achieve near-zero carbon dioxide emissions, which has obvious environmental advantages.

[0063] In the above embodiment, in the present invention, the first synthesis gas can be used as a deoxygenation heat source for the deaerator in a low hydrogen-to-carbon ratio, hydrogen production process or a high hydrogen-to-carbon ratio process, and can fully utilize the high temperature of the reformed raw synthesis gas to provide a heat source for the deaerator, thereby further improving the heat utilization efficiency of the reforming reaction.

[0064] In a specific embodiment of the present invention, Figure 7 As shown, the method also includes:

[0065] d. Separate the carbon dioxide S13 from the second shifted gas S9 to obtain a recombined synthesis gas S22; send the carbon dioxide S13 to the heat exchanger 7 to exchange heat with the first synthesis gas S7, and then use it as the carbon dioxide raw material S17.

[0066] The separation method 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 and hot potassium carbonate method; in a preferred specific embodiment of the present invention, the separation includes sending the second conversion gas S9 into a carbon dioxide absorption tower 11 to contact with an absorption liquid to obtain a recombined synthetic gas S22 and a rich liquid, sending the rich liquid into a carbon dioxide desorption tower 12 for desorption to obtain carbon dioxide S13 and a regenerated absorption liquid, and returning the regenerated absorption liquid to the carbon dioxide absorption tower 11 for recycling.

[0067] In another specific embodiment of the present invention, Figure 7 As shown, the method further includes: before entering the carbon dioxide absorption tower 11 , the second shifted gas S9 enters the cooler 8 to cool down, and then enters the liquid separator 9 , and the separated tank top gas phase enters the carbon dioxide absorption tower 11 .

[0068] In the above-mentioned embodiment, the carbon dioxide separated from the conversion gas is heat exchanged with the high-temperature synthesis gas and returned to the hydrogen production converter as part of the carbon dioxide feedstock to continue the reforming reaction. On the one hand, the reformed crude synthesis gas is fully utilized to provide heat for the reforming reaction feedstock. On the other hand, the separated carbon dioxide is recycled to achieve near-zero carbon dioxide emissions in the synthesis gas production device, which has obvious environmental advantages.

[0069] In a specific embodiment of the present invention, Fig. 9 As shown, the method also includes: mixing the desulfurized hydrogen production raw material and water vapor S2 and sending them to the pre-conversion reactor 16 for reaction after a second heating, and then mixing them with the carbon dioxide raw material S17 and sending them to the radiation unit 2 after a third heating.

[0070] The above embodiment is applicable to hydrogen production raw materials containing heavy hydrocarbon components. The pre-conversion reactor 16 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.

[0071] In a specific embodiment of the present invention, Figure 7 As shown, the method also includes:

[0072] The flue gas S21 of the hydrogen production reformer is sent to the dust collector 13, the flue gas carbon dioxide absorption tower 14 and the flue gas carbon dioxide desorption tower 15 to separate carbon dioxide to obtain the carbon dioxide-depleted flue gas S19 and the carbon dioxide S20 separated from the flue gas of the hydrogen production reformer;

[0073] The carbon dioxide raw material also includes carbon dioxide S20 separated from the reformer flue gas S21 and;

[0074] The carbon dioxide raw material also includes carbon dioxide S14 supplemented from outside the device.

[0075] In the above-mentioned embodiment, the carbon dioxide separated from the flue gas of the hydrogen production converter is heat exchanged with the high-temperature synthesis gas, and returned to the hydrogen production converter as part of the carbon dioxide feedstock to continue the reforming reaction, thereby making full use of the reformed crude synthesis gas to provide heat for the separated carbon dioxide. On the other hand, the separated carbon dioxide is recycled, and the carbon dioxide content in the flue gas discharged from the device is low, thereby achieving near-zero carbon dioxide emissions in the synthesis gas production device, which has obvious environmental advantages.

[0076] In a specific embodiment of the present invention, Figure 7 As shown, the method also includes: before entering the radiation unit 2, the carbon dioxide raw material is pressurized to 0.35-7.0 MPa, preferably 0.35-4.5 MPa through a carbon dioxide compressor 10; the carbon dioxide compressor 10 is selected from one or more of a reciprocating compressor, a centrifugal compressor and a screw compressor, preferably a reciprocating compressor and a screw compressor.

[0077] In a specific embodiment of the present invention, Figure 7 As shown, the method also includes: a bypass line is provided at the inlet of the conversion reactor 6, and the intake amount of the first synthesis gas S7 is controlled by adjusting the bypass line valve. The proportion of the first synthesis gas entering the conversion reactor 6 to the total amount of the first synthesis gas S7 is 0-100%, preferably 0-80%, and it is most preferred that the first synthesis gas S7 does not enter the conversion reactor 6.

[0078] In the above-mentioned embodiment, the intake amount of the first synthesis gas entering the shift reactor is controlled to adjust the hydrogen-carbon ratio of the synthesis gas product, so that the preparation process has the advantages of flexible operation and the ability to meet diversified needs; for example, in one embodiment, hydrogen is used as the target product, and the first synthesis gas S7 needs to be sent to the shift reactor in its entirety; in another embodiment, the preparation of synthesis gas is used as the main product, and the hydrogen-carbon ratio in the synthesis gas is adjusted at the same time, so part of the synthesis gas is adjusted to be sent to the shift reactor; in the third embodiment, the preparation of low hydrogen-carbon ratio synthesis gas is used as the target product, and the first synthesis gas does not enter the shift reactor, but is directly sent to the downstream equipment for separation.

[0079] In a specific embodiment of the present invention, the shift reactor 6 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 fixed bed reactor or a radial bed reactor;

[0080] The conditions for the shift reaction include: a reaction temperature of 120 to 500° C., preferably 200 to 420° C., and a reaction pressure of 0.3 to 6.4 MPa, preferably 0.5 to 3.5 MPa.

[0081] In the present invention, the system of the preparation process of the present invention comprises a hydrodesulfurization unit A1, a convection unit A2, a radiation unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8, a flue gas carbon dioxide recovery unit A9 and a pre-conversion unit A10. The reformed crude synthesis gas S6 is sequentially fed into the steam generation unit A4 and the heat exchange unit A5, and the steam source in the steam generation unit A4 includes one or more of the steam generated by the waste heat boiler, the steam generated by the heat exchange unit A5 and the hydrogen production raw material S1, the steam generated by the heat exchange unit A5 and the carbon dioxide S8, and the steam generated in the deoxidation heat source of the deaerator.

[0082] In a specific embodiment of the present invention, the sulfur content of the hydrogen production feedstock is 0 to 1000 ppm, preferably 0 to 250 ppm. 3 -C 4 The hydrocarbon content is 0 to 10 mol%, preferably 0 to 7.5 mol%.

[0083] In a specific embodiment of the present invention, 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. 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. Compounds, and contain 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 non-condensable gases produced and recovered during the oil refining process of the refinery, and the 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; coke oven gas is mainly composed of hydrogen and methane, and contains a small amount of carbon monoxide, carbon dioxide, nitrogen and other hydrocarbons. In the above embodiment, for example, when selecting hydrogen production raw materials such as light hydrocarbons or naphtha, it is necessary to set a pre-conversion reactor before entering the hydrogen production converter to crack large molecular hydrocarbons into small molecules such as methane and ethane, avoid carbon deposition and deactivation of the hydrogen production converter tube, so as to extend the service life of the reforming catalyst in the hydrogen production converter tube, and further extend the operation cycle and service life of the hydrogen production converter.

[0084] In a specific embodiment of the present invention, the first temperature increase, the second temperature increase and the third temperature increase are performed in the convection unit 1 of the hydrogen production converter and / or through heat exchange of the reforming reaction product flow.

[0085] In a specific embodiment of the present invention, the reaction temperature of the hydrogenation reactor 5 is 220-450°C, preferably 250-350°C, and the reaction temperature of the hydrodesulfurization reactor 3 is 220-430°C, preferably 205-360°C.

[0086] In a specific embodiment of the present invention, the conditions of the catalytic reforming reaction include: a reaction temperature of 550 to 950°C, preferably 600 to 750°C, a reaction pressure of 0.3 to 6.5 MPa, preferably 1.0 to 3.5 MPa, a temperature of the reformed crude synthesis gas S6 of 550 to 950°C, preferably 800 to 900°C, and a pressure of 0.3 to 6.4 MPa, preferably 1.0 to 3.5 MPa.

[0087] In a specific embodiment of the present invention, a reforming reaction catalyst is loaded in the furnace tube of the hydrogen production converter; the reforming catalyst comprises a reforming catalytic active component and an auxiliary agent, 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, preferably a nickel active component, a rhodium active component, a ruthenium active component, a platinum active component and a palladium active component; the auxiliary agent is selected from Al 2 O 3 、SiO 2 , SiC, molecular sieve, TiO 2 , MgO, rare earth metals and rare earth metal oxides, preferably Al 2 O 3 、SiO 2 、SiC、TiO 2 , MgO, rare earth metals and rare earth metal oxides. In the above embodiment, the reforming catalyst selected by the present invention has good low temperature activity and excellent anti-carbon deposition performance, can make more full use of the heat of the synthesis gas at the outlet of the hydrogen production converter, and can ensure the stability of the device under long-term operation of the device.

[0088] In a specific embodiment of the present invention, the molar ratio of hydrogen to carbon monoxide in the crude synthesis gas (S6) is (0.2-3.0):1, preferably (0.4-2.5):1;

[0089] The content of methane in the reformed synthetic gas S22 is less than 150 ppm, preferably less than 100 ppm, and the content of carbon dioxide is less than 300 ppm, preferably less than 200 ppm; the molar ratio of hydrogen to carbon monoxide in the reformed synthetic gas S22 is (0.5-3.5):1, preferably (0.7-3.5):1.

[0090] 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.

[0091] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0092] Example 1

[0093] This embodiment includes a hydrodesulfurization unit A1, a radiation unit A2, a convection unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8 and a flue gas carbon dioxide recovery unit A9.

[0094] The raw material for hydrogen production in this embodiment is natural gas, the sulfur content of natural gas is 50ppm, and the fuel of the hydrogen production converter is natural gas and the desorbed gas separated by the PSA unit. The active component of the reforming catalyst used in this embodiment is a nickel-ruthenium active component, and the auxiliary agent is Al 2 O 3 The carbon dioxide compressor 10 used in this embodiment is a reciprocating compressor. The preparation process flow chart is as follows Figure 1 , Figure 7 shown.

[0095] a. The hydrogen production raw material S1 is heated to 150°C and sent to the hydrogenation reactor 5 and the hydrodesulfurization reactor 3 in sequence to obtain a desulfurized hydrogen production raw material.

[0096] b. Mix the desulfurized hydrogen production raw material S1, water vapor S2 and carbon dioxide raw material S17 of step a, heat them to 550° C. to obtain a mixed raw material, send the mixed raw material into the radiation unit 2 of the hydrogen production converter to contact with the reforming catalyst, and carry out a catalytic reforming reaction, and obtain a reformed crude synthesis gas S6 from the outlet of the radiation unit 2 of the hydrogen production converter, and cool the reformed crude synthesis gas S6 through the steam generator 4 to obtain a first synthesis gas S7. Among them, the temperature of the catalytic reforming reaction is 850° C., the reaction pressure is 3.3 MPa, the temperature of the reformed crude synthesis gas S6 is 830° C., the pressure is 3.2 MPa, and the temperature of the first synthesis gas S7 is 410° C., and the pressure is 3.15 MPa.

[0097] c. Send all the first synthesis gas S7 in step b to the by-line of the shift reactor without entering the shift reactor. The first synthesis gas S7 is sequentially sent to the shell inlet of the heat exchanger 7 through the by-line of the shift reactor to obtain the second shift gas S9. The second shift gas S9 is sent to the cooler 8 for cooling to obtain the third shift gas S10. The third shift gas S10 enters the separator 9. The condensate is separated from the bottom of the separator 9. The top gas phase S12 is sent to the carbon dioxide absorption tower 11 to separate carbon dioxide. Among them, the top gas phase S12 contacts with the MDEA solution in the carbon dioxide absorption tower 11 to obtain the recombined synthesis gas S22 and the rich liquid. The rich liquid that absorbs carbon dioxide is desorbed in the carbon dioxide desorption tower 12 to obtain carbon dioxide S13 and the regenerated absorption liquid.

[0098] d. The flue gas S21 at the outlet of the radiation unit 1 is sequentially sent to the dust collector 13, the flue gas carbon dioxide absorption tower 14 and the flue gas carbon dioxide desorption tower 15 to separate and obtain carbon dioxide S20. The flue gas S21 contacts with the MEDA solution in the flue gas carbon dioxide absorption tower 14 to absorb and desorb.

[0099] e. The carbon dioxide S13 in step c, the carbon dioxide S20 in step d and the carbon dioxide S14 supplemented outside the device are sent to the carbon dioxide compressor 10 to be pressurized to 3.6MPa to obtain pressurized carbon dioxide S15. The pressurized carbon dioxide S15 is heat exchanged with the first synthesis gas S7 in the heat exchanger 7 to obtain the first heated carbon dioxide S16. The first heated carbon dioxide S16 is sent to the convection unit 1 to be heated to 350°C to obtain carbon dioxide raw material S17. The carbon dioxide raw material S17 is mixed with the hydrogen production raw material S1 and water vapor S2 and heated to 550°C before being sent to the hydrogen production converter to continue the reforming reaction.

[0100] Example 2

[0101] This embodiment includes a hydrodesulfurization unit A1, a radiation unit A2, a convection unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8 and a flue gas carbon dioxide recovery unit A9.

[0102] The preparation process flow chart of this embodiment is as follows Figure 2 , Figure 8 shown.

[0103] The method of Example 1 is adopted, the only difference being that the carbon dioxide in the flue gas S21 at the outlet of the hydrogen production converter is not separated, wherein the carbon dioxide raw material S17 includes carbon dioxide S13 separated from the tank top gas phase S12 and carbon dioxide S14 supplemented outside the device.

[0104] Example 3

[0105] This embodiment includes a hydrodesulfurization unit A1, a radiation unit A2, a convection unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8, a flue gas carbon dioxide recovery unit A9 and a pre-conversion reaction unit A10.

[0106] The hydrogen production raw material in this embodiment is refinery dry gas, and the C 3 -C 4 The hydrocarbon content is 5.5 mol%. The preparation process flow chart is as follows Figure 3 , Fig. 9 shown.

[0107] The method of Example 1 is adopted, with the only difference that the desulfurized hydrogen-producing raw material and water vapor S2 are mixed and heated to 430°C, and sent to the pre-conversion reactor 16 for reaction to obtain a reaction material; the carbon dioxide raw material S17 is mixed with the reaction material and heated to 570°C, and then sent to the radiation unit 2 of the hydrogen-producing converter.

[0108] Example 4

[0109] This embodiment includes a hydrodesulfurization unit A1, a radiation unit A2, a convection unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8 and a flue gas carbon dioxide recovery unit A9.

[0110] The carbon dioxide compressor 10 used in this embodiment is a screw compressor. The preparation process flow chart of this embodiment is as follows Figure 4 , Fig.10 shown.

[0111] The method of Example 1 is adopted, with the only difference that the carbon dioxide raw material S17 is entirely derived from the carbon dioxide S14 supplemented outside the device, wherein the carbon dioxide S14 supplemented outside the device is pressurized to 4.5 MPa by a screw compressor to obtain pressurized carbon dioxide S15, the pressurized carbon dioxide S15 is heat exchanged with the first synthesis gas S7 in a heat exchanger 7 to obtain a first heated carbon dioxide S16, the first heated carbon dioxide S16 is sent to a convection unit 1 to be heated to 380°C to obtain a carbon dioxide raw material S17, the carbon dioxide raw material S17 is mixed with a hydrogen production raw material S1 and water vapor S2, the temperature is raised to 550°C, and then sent to a hydrogen production converter to continue the reforming reaction.

[0112] Example 5

[0113] This embodiment includes a hydrodesulfurization unit A1, a radiation unit A2, a convection unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8 and a flue gas carbon dioxide recovery unit A9.

[0114] The carbon dioxide compressor 10 used in this embodiment is a screw compressor. The preparation process flow chart of this embodiment is as follows Figure 4 , Fig.11 shown.

[0115] The method of Example 4 is adopted, the only difference being that the pressurized carbon dioxide S15 is heat exchanged with the first synthesis gas S7 in the heat exchanger 7 to obtain the carbon dioxide raw material S17, and the temperature of the carbon dioxide raw material S17 is 350°C.

[0116] Example 6

[0117] This embodiment includes a hydrodesulfurization unit A1, a radiation unit A2, a convection unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8 and a flue gas carbon dioxide recovery unit A9.

[0118] The preparation process flow chart of this embodiment is as follows Figure 5 , Fig.12 shown.

[0119] The method of Example 3 is adopted, the only difference being that the carbon dioxide raw material S17 is entirely derived from carbon dioxide S14 supplemented outside the device.

[0120] Example 7

[0121] This embodiment includes a hydrodesulfurization unit A1, a radiation unit A2, a convection unit A3, a steam generation unit A4, a heat exchange unit A5, a carbon dioxide separation unit A6, a carbon dioxide boosting unit A7, a flue gas pretreatment unit A8 and a flue gas carbon dioxide recovery unit A9.

[0122] The preparation process flow chart of this embodiment is as follows Figure 6 , Fig.13 shown.

[0123] The method of Example 3 is adopted, except that the carbon dioxide raw material S17 is entirely derived from the carbon dioxide S14 supplemented outside the device, and the pressurized carbon dioxide S15 is sent to the convection unit 1 of the hydrogen production converter to be heated to 370° C. to obtain the carbon dioxide raw material S17. Among them, 30% of the first synthesis gas S7 is sent to the shift reactor 6, and the heat exchanger 7 is not set on the outlet pipeline of the shift reactor 6, and a deaerator 17 is set to fully utilize the heat of the synthesis gas.

[0124] Test Case

[0125] The reformed synthetic gas S22 of Examples 1 to 7 was tested as follows:

[0126] 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;

[0127] The methane content was determined by gas chromatography, the carbon dioxide content was determined by gas chromatography, and the steam amount was read directly by a mass flow meter set in the steam line.

[0128] Table 1

[0129]

[0130] According to the test results in Table 1, it can be seen that the preparation method provided by the present invention can prepare low hydrogen-to-carbon ratio, high value-added reformed synthetic gas without changing the existing hydrogen production converter, and the carbon dioxide raw material is recycled in the preparation process, which can achieve near-zero carbon dioxide emissions and has obvious environmental advantages; at the same time, the process equipment has a long operating cycle and service life, and the process energy consumption and cost are low.

[0131] 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, and the content of carbon dioxide in the reformed synthetic gas is low, the carbon dioxide emissions of the device are low, the environmental protection advantages are obvious, and the operation cycle is long.

[0132] 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.

[0133] 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.

[0134] 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, wherein: The method includes: a. feeding the hydrogen production raw material (S1) into the hydrogenation reactor (5) and the hydrodesulfurization reactor (3) in sequence after the first heating to obtain a desulfurized hydrogen production raw material; b. mixing the desulfurized hydrogen production raw material (S1), water vapor (S2) and carbon dioxide raw material (S17) and performing a second heating to obtain a mixed raw material, feeding the mixed raw material into a radiation unit (2) of a hydrogen production converter to contact with a reforming catalyst to perform a catalytic reforming reaction, obtaining a reformed crude synthesis gas (S6) from the outlet of the radiation unit (2) of the hydrogen production converter, and cooling the reformed crude synthesis gas (S6) through a steam generator (4) to obtain a first synthesis gas (S7); c. optionally sending the first synthesis gas (S7) into a shift reactor (6) for a shift reaction to obtain a first shifted gas (S8); sending the first shifted gas (S8) into a heat exchanger (7) for heat exchange to obtain a second shifted gas (S9); wherein, before entering the radiation unit (2), at least a portion of the carbon dioxide feedstock (S17) is allowed to enter the heat exchanger (7) for heat exchange with the first synthesis gas (S7); or c' Using the first synthesis gas (S7) as a deoxygenation heat source for a deaerator.

2. The method according to claim 1, wherein: The method further includes: d. separating the carbon dioxide (S13) from the second shifted gas (S9) to obtain a reformed synthesis gas (S22); sending the carbon dioxide (S13) to the heat exchanger (7) to exchange heat with the first synthesis gas (S7), and then using it as the carbon dioxide raw material (S17); The separation method 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; preferably, the separation includes sending the second conversion gas (S9) into a carbon dioxide absorption tower (11) to contact with an absorption liquid to obtain the recombined synthetic gas (S22) and rich liquid, sending the rich liquid into a carbon dioxide desorption tower (12) for desorption to obtain the carbon dioxide (S13) and regenerated absorption liquid, and returning the regenerated absorption liquid to the carbon dioxide absorption tower (11) for recycling; Optionally, the method further comprises: before entering the carbon dioxide absorption tower (11), allowing the second conversion gas (S9) to enter a cooler (8) for cooling, and then enter a liquid separator (9), and the separated tank top gas phase enters the carbon dioxide absorption tower (11).

3. The method according to claim 1, wherein: The method further comprises: mixing the desulfurized hydrogen production raw material and water vapor (S2) and sending them into a pre-conversion reactor (16) for reaction after a second heating, and then mixing them with the carbon dioxide raw material (S17) and sending them into the radiation unit (2) after a third heating.

4. The method according to claim 1, wherein: The method further includes: The flue gas (S21) of the hydrogen production reformer is sent to a dust collector (13), a flue gas carbon dioxide absorption tower (14) and a flue gas carbon dioxide desorption tower (15) to separate carbon dioxide, thereby obtaining carbon dioxide-depleted flue gas (S19) and carbon dioxide separated from the flue gas of the hydrogen production reformer (S20); The carbon dioxide raw material also includes carbon dioxide (S20) separated from the flue gas (S21) of the hydrogen production converter and; Optionally, the carbon dioxide raw material also includes carbon dioxide supplemented from outside the device (S14).

5. The method according to claim 1, wherein: The method further comprises: before entering the radiation unit (2), the carbon dioxide raw material is pressurized to 0.35-7.0 MPa by a carbon dioxide compressor (10); the carbon dioxide compressor (10) is selected from one or more of a reciprocating compressor, a centrifugal compressor and a screw compressor.

6. The method according to claim 1, wherein: The method also includes: a secondary line is provided at the inlet of the shift reactor (6), and the intake amount of the first synthesis gas (S7) is controlled by adjusting the secondary line valve, and the proportion of the first synthesis gas entering the shift reactor (6) to the total amount of the first synthesis gas (S7) is 0 to 100%.

7. The method according to claim 1, wherein: The shift reactor (6) is one or more of a shell-and-tube reactor, a fixed bed reactor, a radial bed reactor and an axial radial reactor; The conditions of the shift reaction include: a reaction temperature of 120 to 500° C. and a reaction pressure of 0.3 to 6.4 MPa.

8. The method according to claim 1, wherein: The sulfur content of the hydrogen production raw material is 0 to 1000 ppm, and the C3-C4 hydrocarbon content of the hydrogen production raw material is 0 to 10 mol%; 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; The first temperature increase, the second temperature increase and the third temperature increase are carried out in the radiation unit (1) of the hydrogen production converter and / or through heat exchange of the reforming reaction product stream; The reaction temperature of the hydrogenation reactor (5) is 220-450°C, and the reaction temperature of the hydrodesulfurization reactor (3) is 220-430°C.

9. The method according to claim 1, wherein: The conditions of the catalytic reforming reaction include: a reaction temperature of 550-950°C, a reaction pressure of 0.3-6.5 MPa, a temperature of the reformed crude synthesis gas (S6) of 550-950°C, and a pressure of 0.3-6.4 MPa; The furnace tube of the hydrogen production converter is filled with a reforming reaction catalyst; the reforming catalyst includes a reforming catalytic active component and an auxiliary agent, 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 crude synthesis gas (S6) is (0.2-3.0):1; The content of methane in the reformed synthetic gas (S22) is less than 150 ppm, and the content of carbon dioxide is less than 300 ppm; the molar ratio of hydrogen to carbon monoxide in the reformed synthetic gas (S22) is (0.5-3.5):1.

Images