Natural gas steam conversion system and process

Abstract

The invention discloses a natural gas steam conversion system and process, and the natural gas steam conversion system comprises a natural gas steam conversion device, a carbon dioxide separation system, a converted gas heat exchanger group and an air preheater; the natural gas steam conversion device comprises a conversion furnace and a reaction gas conversion system consisting of a tubular reactor, a conversion reactor, a gas-liquid separator and a pressure swing adsorption hydrogen extraction system. The heat value of the pressure swing adsorption tail gas is increased through the carbon dioxide separation system to obtain high-heat-value separated gas, and then the high-heat-value separated gas is adopted as fuel gas to be combusted with oxygen-enriched gas to supply heat required by conversion to raw material gas in the tubular reactor; the air preheater is used for preheating oxygen-enriched gas, the fuel gas / converted gas heat exchanger is used for preheating high-calorific-value separated gas, flue gas waste heat is recycled to the maximum extent, the byproduct steam amount is reduced, and the purpose of reducing or not outputting medium-pressure or high-pressure superheated steam is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas steam reforming, and particularly to a natural gas steam reforming system and process. Background Art

[0002] Currently, the processes widely used for producing hydrogen, syngas, pure hydrogen, and pure carbon monoxide include several conventional process routes such as natural gas steam reforming, natural gas partial oxidation, and solid or liquid gasification. Among them, natural gas steam reforming is mainly used worldwide for producing pure hydrogen, and partly for producing syngas or pure hydrogen and pure carbon monoxide products.

[0003] Generally, natural gas steam reforming uses air, fuel gas, and pressure swing adsorption tail gas for combustion to provide the heat required for the natural gas steam reforming process in the reformer. The flue gas discharged from the radiant section of the reformer to the convection section contains a large amount of heat, which needs to be exchanged with the raw material gas, air, boiler feed water, steam, etc. to recover the heat. During the heat exchange process, a large amount of medium-pressure or high-pressure superheated steam is often by-produced. Part of it is used for the natural gas steam reforming process, and the other part is sent out as by-product steam to the off-site medium-pressure or high-pressure superheated steam pipeline network.

[0004] Since conventional natural gas steam reforming units will by-produce a large amount of medium-pressure or high-pressure superheated steam, the factory needs to have corresponding users of the medium-pressure or high-pressure superheated steam pipeline network, such as steam turbines, generators, etc. However, with the increasingly strict requirements for carbon emission indicators, some factories have begun to convert steam to electricity. For example, the air compressors and boosters in the air separation unit have been successively converted to motor drive. This requires that newly built natural gas steam reforming units need to consider reducing or not producing external medium-pressure or high-pressure superheated steam to be applicable to large natural gas steam reforming units and hydrogen refueling stations to be built in the future where there are no medium-pressure or high-pressure superheated steam users nearby.

[0005] When there are no medium-pressure superheated steam users, the conventional natural gas steam reforming process needs to be adjusted to reduce the steam production or not by-produce external medium-pressure superheated steam. At this time, a converted gas self-heat exchange reactor needs to be set at the converted gas outlet, or the process can also be adjusted by adding a raw material adiabatic pre-reactor. By reducing the process heat demand and then reducing the fuel gas volume, the flue gas volume is reduced, and only the medium-pressure superheated steam required for the natural gas steam reforming process itself is produced within the process, and no medium-pressure superheated steam is by-produced and sent out. The natural gas steam reforming device provided with the self-heat exchange reforming reactor and the raw material adiabatic pre-reactor is more complex to operate compared with the process of only setting the reforming reaction furnace tubes. In addition, it also increases the additional work of catalyst loading or replacement. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects that a large amount of medium-pressure or high-pressure superheated steam is by-produced in the existing natural gas steam reforming device, or the process is relatively complex when a conversion gas self-heat exchange reactor and a raw material adiabatic pre-reactor are used for treatment, so as to provide a natural gas steam reforming system and process with reduced by-produced steam output and relatively simple process.

[0007] A natural gas steam reforming system, comprising:

[0008] A natural gas steam reforming device, comprising a reforming furnace and a reaction gas reforming system. The reaction gas reforming system includes a tubular reactor, a shift reactor, a gas-liquid separator, and a pressure swing adsorption hydrogen production system that are connected in sequence. The reforming furnace includes a radiant section and a convection section. The tubular reactor is arranged in the radiant section. The tubular reactor has a raw material input end. The pressure swing adsorption hydrogen production system has a hydrogen output end and a pressure swing adsorption tail gas output end. The radiant section has a fuel gas input end and an oxygen-rich gas input end. The convection section has a flue gas discharge end;

[0009] A carbon dioxide separation system, which is connected to the pressure swing adsorption tail gas output end; the carbon dioxide separation system has a carbon dioxide output end and a separated gas output end; the separated gas output end is connected to the fuel gas input end;

[0010] A conversion gas heat exchanger group is arranged on the connecting pipeline between the tubular reactor and the shift reactor; at least a fuel gas / conversion gas heat exchanger is included in the conversion gas heat exchanger group. The separated gas output from the separated gas output end is heated through the fuel gas / conversion gas heat exchanger and then enters the radiant section of the reforming furnace through the fuel gas input end;

[0011] An air preheater is further arranged on the convection section; the oxygen-rich gas is preheated through the air preheater and then input into the radiant section through the oxygen-rich gas input end.

[0012] The reaction gas reforming system further includes a steam generator, and the steam generator is arranged on the convection section of the reforming furnace; a steam drum is further connected to the steam generator. The steam drum includes a water input end, a water output end, a steam output end, and a steam input end. The steam output end is connected to the raw material input end, and the steam input end is connected to the steam outlet of the steam generator.

[0013] The steam generator includes a first steam generator having a first water inlet and a first steam outlet and a second steam generator having a second water inlet and a second steam outlet;

[0014] The water output end is connected to the first water inlet of the first steam generator and the second water inlet of the second steam generator. The first steam outlet is connected to the steam input end of the steam drum;

[0015] An oxygen deaerator is also connected to the water input end of the steam drum, and the second steam outlet of the second steam generator and / or the steam output end of the steam drum communicate with the oxygen deaerator;

[0016] The water in the oxygen deaerator enters the steam drum through the water input end after being deaerated.

[0017] A raw material gas preheater and a steam superheater are also arranged on the convection section; the steam output from the steam output end is heat-exchanged in the steam superheater and then mixed with the raw materials to form a raw material gas (the water-carbon ratio S / C of the raw material gas is about 3.3 - 3.5), and the raw material gas is heat-exchanged in the raw material gas preheater and then input into the tubular reactor through the raw material input end.

[0018] On the convection section, the second steam generator, the raw material gas preheater, the steam superheater, the first steam generator, and the air preheater are arranged in sequence along the conveying direction of the flue gas.

[0019] A shift gas heat exchanger group is arranged on the connecting pipeline between the shift reactor and the gas-liquid separator; the shift gas heat exchanger group includes at least a raw material gas / shift gas heat exchanger;

[0020] There are two raw material gas / shift gas heat exchangers, namely the raw material gas / shift gas heat exchanger I and the raw material gas / shift gas heat exchanger II; the conversion gas heat exchanger group also includes a raw material gas / conversion gas heat exchanger; the raw materials are sequentially heat-exchanged in the raw material gas / conversion gas heat exchanger, the raw material gas / shift gas heat exchanger I, and the raw material gas / shift gas heat exchanger II and then input into the raw material input end of the tubular reactor.

[0021] The conversion gas heat exchanger group also includes a conversion gas waste heat boiler, and the water in the steam drum is input into the conversion gas waste heat boiler to be heat-exchanged with the conversion gas and then returns to the steam drum; the conversion gas waste heat boiler, the fuel gas / conversion gas heat exchanger, and the raw material gas / conversion gas heat exchanger in the conversion gas heat exchanger group are arranged in sequence along the conveying direction of the conversion gas;

[0022] And / or, the reaction gas conversion system also includes a desulfurization / hydrogenation reactor, and the desulfurization / hydrogenation reactor is connected to the raw material outlet of the raw material gas / shift gas heat exchanger II.

[0023] The liquid output end of the gas-liquid separator communicates with the oxygen deaerator; and / or, a demineralized water input end is also arranged on the oxygen deaerator;

[0024] And / or, the shift gas heat exchanger group also includes a deaerated water / shift gas heat exchanger; the water output from the oxygen deaerator enters the deaerated water / shift gas heat exchanger to be heat-exchanged with the shift gas and then enters the steam drum through the water input end.

[0025] The desalted water / shift gas heat exchanger is also included in the shift gas heat exchanger group. After heat exchange in the desalted water / shift gas heat exchanger, the desalted water enters the deaerator through the desalted water input end;

[0026] In the shift gas heat exchanger group, the raw material gas / shift gas heat exchanger II, the deaerated water / shift gas heat exchanger, the raw material gas / shift gas heat exchanger I, and the desalted water / shift gas heat exchanger are arranged in sequence along the conveying direction of the shift gas.

[0027] There are two groups of gas-liquid separators, namely the gas-liquid separator I and the gas-liquid separator II arranged in series. A shift gas final cooler is also arranged between the gas-liquid separator I and the gas-liquid separator II.

[0028] A natural gas steam reforming process uses the above-mentioned natural gas steam reforming system for treatment.

[0029] The technical solution of the present invention has the following advantages:

[0030] 1. In the present invention, the carbon dioxide in the pressure swing adsorption tail gas is separated to the greatest extent through the carbon dioxide separation system to increase the calorific value of the pressure swing adsorption tail gas and obtain a high-calorific value separated gas. Then, the high-calorific value separated gas is used as fuel gas to burn with oxygen-rich gas to supply the heat required for the conversion of the raw material gas in the tubular reactor. At the same time, the oxygen-rich gas is preheated through the air preheater, and the separated gas used as fuel gas is preheated through the fuel gas / conversion gas heat exchanger. By cooperating with each other, the waste heat of the flue gas is recovered to the greatest extent, the amount of by-product steam is reduced, and the purpose of reducing the medium-pressure or high-pressure superheated steam output from the natural gas steam reforming device is achieved. Even the purpose of reducing the medium-pressure or high-pressure superheated steam output can be achieved;

[0031] In the present invention, only a carbon dioxide separation system needs to be added. Without the need to set up a self-heat exchange type reforming reactor and a raw material adiabatic pre-reactor, the purpose of reducing or even not outputting medium-pressure or high-pressure superheated steam can be achieved, thereby ensuring the simplicity of the process operation.

[0032] 2. In the present invention, by setting a steam generator in the convection section, the heat obtained from the combustion of fuel gas and oxygen-rich gas can be further effectively utilized, saving energy consumption.

[0033] 3. In the present invention, through the mutual cooperation of the steam drum, the deaerator, and the steam generator, stable steam supply in the tubular reactor can be achieved.

[0034] 4. In the present invention, by setting a raw material gas preheater and a steam superheater in the convection section, the temperature of the raw material gas can be further increased, and then the heat obtained from the combustion of fuel gas and oxygen-rich gas can be more effectively utilized, further saving energy consumption.

[0035] 5. The present invention is arranged successively along the flue gas conveying direction in the convection section according to the different temperature requirements of the substances after heat exchange in the second steam generator, the raw material gas preheater, the steam superheater, the first steam generator, and the air preheater, and is arranged successively along the conveying direction of the conversion gas according to the different temperature requirements of the substances after heat exchange in the conversion gas waste heat boiler, the fuel gas / conversion gas heat exchanger, and the raw material gas / conversion gas heat exchanger. According to the different temperature requirements of the substances after heat exchange in the raw material gas / shift gas heat exchanger II, the deaerated water / shift gas heat exchanger, the raw material gas / shift gas heat exchanger I, and the desalted water / shift gas heat exchanger, it is arranged successively along the conveying direction of the shift gas, which can better utilize the heat of the flue gas, the conversion gas, and the shift gas in the convection section. Through the optimization of the above heat exchange network, finally, all the by-produced medium-pressure steam is used internally in the natural gas steam reforming device, and there is no external output of by-produced medium-pressure superheated steam. At the same time, the heat utilization rate is improved and the energy consumption is reduced.

[0036] 6. The present invention heats the raw material successively through the raw material gas / conversion gas heat exchanger, the raw material gas / shift gas heat exchanger I, and the raw material gas / shift gas heat exchanger II, so as to increase the temperature of the raw material entering the tubular reactor, thereby reducing the heat required to reach the conversion temperature and reducing the energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 is a schematic structural diagram of the present invention;

[0039] Reference Numerals:

[0040] R101 - Desulfurization / Hydrogenation Reactor; R102 - Shift Reactor; R103 - Tubular Reactor; F101 - Reformer; B101 - Blower; B102 - Induced Draft Fan; D101 - Steam Drum; D102 - Deaerator; P101 - Deaerated Water Pump;

[0041] E101 - Raw Material Gas / Conversion Gas Heat Exchanger; E102 - Raw Material Gas / Shift Gas Heat Exchanger I; E103 - Raw Material Gas / Shift Gas Heat Exchanger II; E104 - Conversion Gas Waste Heat Boiler; E105 - Fuel Gas / Conversion Gas Heat Exchanger; E106 - Deaerated Water / Shift Gas Heat Exchanger; E107 - Desalted Water / Shift Gas Heat Exchanger; E108 - Shift Gas Final Cooler;

[0042] E111 - Second steam generator; E112 - Feed gas preheater; E113 - Steam superheater; E114 - First steam generator; E115 - Air preheater;

[0043] V101 - Gas - liquid separator I; V102 - Gas - liquid separator II; Z101 - Pressure swing adsorption hydrogen production system; Z102 - Carbon dioxide separation system. Specific embodiments

[0044] The following embodiments are provided to better further understand the present invention. It is not limited to the described best embodiment, and does not limit the content and protection scope of the present invention. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other existing technologies and being the same as or similar to the present invention falls within the protection scope of the present invention.

[0045] In the description of the present invention, it should be noted that the orientation or positional relationships indicated by the terms "side", "upper", "lower", "top", "bottom", "vertical", "horizontal", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0047] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] Embodiment 1

[0049] A natural gas steam reforming system, as Figure 1 shown, and its specific process is as follows:

[0050] The raw material 100 (pressure 3.7MPaG, temperature 40°C) from the off-site pipeline network is heated to 110°C by the raw gas / conversion gas heat exchanger E101, and then enters the raw gas / conversion gas heat exchanger I, i.e. E102. The temperature is further increased to 160°C by the heat exchanger, and then enters the raw gas / conversion gas heat exchanger II, i.e. E103. After being heated to 350°C, it enters the desulfurization / hydrogenation reactor R101, and the desulfurization / hydrogenation saturation reaction is completed in the desulfurization / hydrogenation reactor R101. Figure 1 The desulfurization / hydrogenation reactor R101 is a simple schematic diagram, which combines desulfurization and hydrogenation. The catalyst used for desulfurization is ZnO, and the catalyst used for hydrogenation is Co-Mo catalyst. The desulfurized and hydrogenated raw material is mixed with the medium-pressure superheated steam (pressure 3.7 MPaG, temperature 420°C) sent from the steam superheater E113 of the convection section of the converter F101 to form a raw gas (raw material + medium-pressure superheated steam, water-to-carbon ratio S / C is about 3.3), and then preheated to 550°C ~ 630°C by the raw gas preheater E112 of the convection section of the converter F101 to obtain the raw gas 106. The raw gas 106 enters the tubular reactor R103 in the converter F101. The Ni-based catalyst is used in the tubular reactor R103 for conversion. The temperature of the conversion gas 108 sent out from the bottom of the tubular reactor R103 is about 860°C. After that, the conversion gas enters each heat exchanger in the conversion gas heat exchanger group and the conversion gas heat exchanger group for heat recovery.

[0051] The conversion gas 108 is first cooled to 390°C in the conversion gas waste boiler E104, and the deoxygenated water sent from the drum D101 is partially vaporized in the conversion gas waste boiler E104 and returned to the drum D101 through thermal siphon action. The cooled conversion gas continues to exchange heat with the fuel gas in the fuel gas / conversion gas heat exchanger E105. The conversion gas is then cooled to 340°C after heat exchange in the raw gas / conversion gas heat exchanger E101 and then enters the conversion reactor R102. The catalyst used in the conversion reactor R102 is an Fe-based catalyst.

[0052] The conversion gas undergoes a water-gas shift reaction in the shift reactor R102, where carbon monoxide reacts with water vapor to produce hydrogen and carbon dioxide, maximizing hydrogen production and reducing raw material consumption. After the reaction occurs in the shift reactor R102, the outlet temperature of the shift reactor R102 rises to around 400 °C. The shift gas output from the shift reactor R102 is then cooled to around 355 °C in the raw material gas / shift gas heat exchanger II, i.e., E103. Subsequently, the shift gas is further cooled to around 182 °C in the deoxygenated water / shift gas heat exchanger E106, and then cooled to around 170 °C in the raw material gas / shift gas heat exchanger I, i.e., E102. The cooled shift gas is sent to the demineralized water / shift gas heat exchanger E107 for further cooling to around 160 °C. The cooled shift gas undergoes gas-liquid separation in the gas-liquid separator I, i.e., V101. The shift gas after separating the liquid phase continues to enter the shift gas final cooler E108 (which can be an air cooler, a water cooler, or a combination of an air cooler + water cooler) and is cooled to 40 °C after heat exchange with air and / or circulating water. The shift gas cooled by the shift gas final cooler E108 is further separated in the gas-liquid separator II, i.e., V102 to remove the liquid phase, and then the shift gas after separating the liquid phase is sent to the pressure swing adsorption hydrogen production system Z101. After pressure swing adsorption, pure hydrogen 120 and pressure swing adsorption tail gas are obtained. The pure hydrogen 120 is sent to the off-site pipeline network (a small amount is returned to the raw material gas inlet of the natural gas steam reforming process as recycled hydrogen), and the pressure swing adsorption tail gas is sent to the carbon dioxide separation system Z102.

[0053] The carbon dioxide separation system Z102 separates most of the carbon dioxide components from the pressure swing adsorption tail gas, which can be used for carbon capture or directly discharged to the atmosphere. The main components of the pressure swing adsorption tail gas after decarbonization are hydrogen, methane, and carbon monoxide (which can account for approximately H2 = 45 v%, CH4 = 30 v%, and CO = 20 v% respectively), and the rest are nitrogen, water vapor, and a small amount of carbon dioxide. The LHV of the pressure swing adsorption tail gas after decarbonization is 32.44 MJ / kg, while the LHV of the pressure swing adsorption tail gas without decarbonization is 7.18 MJ / kg. By increasing the calorific value of the pressure swing adsorption tail gas through the carbon dioxide separation system Z102, the fuel gas consumption can be significantly reduced. Reducing the fuel gas means a significant reduction in the flue gas volume of the reformer F101, and the by-product medium-pressure steam volume can also be greatly reduced, or even no off-site medium-pressure superheated steam is by-produced.

[0054] Fuel gas is obtained by adding or not adding supplementary natural gas to the pressure swing adsorption tail gas after decarbonization (the high-calorific value separated gas). The fuel gas is heated to around 320 °C after heat exchange in the fuel gas / conversion gas heat exchanger E105, and the heated fuel gas 129 is sprayed into the reformer F101 for combustion to provide heat for the tubular reactor R103 in the reformer F101.

[0055] Conventional fuel gas is not preheated or the preheated temperature is limited, but natural gas can be heated to about 320℃-350℃, and the maximum preheating temperature of natural gas can be 450℃. The present invention can preheat the fuel gas (decarbonization pressure swing adsorption tail gas + supplementary natural gas) to 320℃ by mixing supplementary natural gas with high calorific value separation gas as fuel gas, which can further reduce the fuel gas consumption, the flue gas volume can also be further reduced, and finally the amount of by-product medium-pressure superheated steam can be reduced to only be used internally in the natural gas steam reforming process, without external transmission of medium-pressure superheated steam.

[0056] The combustion air injected into the reformer F101 together with the fuel gas 129 can be a mixture of air from the atmosphere and oxygen-enriched / pure oxygen, or can be directly drawn from an oxygen-enriched generation system, such as pressure swing adsorption oxygen production, air cryogenic separation and other processes. The air is pressurized by the blower B101 and mixed with oxygen-enriched / pure oxygen to obtain combustion air. The oxygen content of the combustion air is about 35v%. After the combustion air is heated to about 300°C by the air preheater E115 of the convection section of the reformer F101, the heated combustion air 153 is injected into the reformer F101 to react with the fuel gas 129 to provide most of the heat required for the natural gas steam reforming process.

[0057] The liquid phase separated by the gas-liquid separator I is combined with the liquid phase separated by the gas-liquid separator II to form a process condensate, which is sent to the top of the deaerator D102 for stripping, and the preheated desalted water is also sent to the top of the deaerator D102 for stripping. The deoxygenated water after stripping in the deaerator D102 is pressurized by the deoxygenated water pump P101, and the deoxygenated water after pressurization is heat exchanged by the deoxygenated water / conversion gas heat exchanger E106, and the preheated deoxygenated water is directly sent to the drum D101. The drum D101 in the present invention can be divided into a conversion gas drum and a convection section drum, or the two can be combined into one.

[0058] The deoxygenated water in the drum D101 can also be sent to the reforming gas waste boiler E104 and the first steam generator E114 of the convection section through the thermosyphon effect for heat exchange and partial vaporization, and then return to the drum D101. The medium-pressure saturated steam is then heated to 420°C by the steam superheater E113 of the convection section to obtain the pressurized and heated steam 144, and the steam 144 is merged into the raw gas pipeline. The deoxygenated water in the drum D101 can also be sent to the second steam generator E111 of the convection section through the thermosyphon effect for heating to obtain a steam-water mixture, which can be first sent to the drum D101, and then extracted from the drum D101 through the gas phase and sent to the deaerator D102. For simplicity, the figure only shows that it is directly sent to the deaerator D102.

[0059] Through the above natural gas steam reforming process, the present invention reduces or even eliminates the need to send medium-pressure / high-pressure superheated steam externally by coordinating processes such as combustion of oxygen-rich gas and pressure swing adsorption tail gas with high calorific value, raw material gas preheating, oxygen-rich gas / pure oxygen preheating, air preheating, and carbon dioxide separation. This can meet the requirements of a new natural gas steam reforming plant without medium-pressure / high-pressure superheated steam users around it.

[0060] In this embodiment, the main material parameters of the above natural gas steam reforming process without by-product steam output are shown in Table 1 below.

[0061] Table 1 - Inlet and outlet material table of natural gas steam reforming process

[0062] Unit 100 106 108 129 144 153 120 Temperature ℃ 40 550 860 320 420 300 40 Pressure BarA 38 33 30 4.5 38 1.15 26 C1 0.9291 0.2055 0.0333 0.3281 / / / C2 0.0313 0.0069 / 0.0017 / / / C3 0.0090 0.0020 / 0.0005 / / / H2 / 0.0111 0.4576 0.4314 / / 0.9999 CO / / 0.0796 0.1938 / / Traces CO2 0.0069 0.0015 0.0565 0.0004 / / / O2 / / / / / 0.35 / N2 0.0183 0.0041 0.0030 0.0258 / 0.65 Traces H2O / 0.7677 0.3700 0.0181 1.0000 / /

[0063] In the above table, the contents in materials such as raw material 100 are volume percentage content values. For the actual product H2, it is required that H2≥99.9v%. Under the system and process of the present invention, H2≥99.99v% can be achieved in conventional production, and there is no by-product steam output.

[0064] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A natural gas steam reforming system, characterized in that, Comprising: A natural gas steam reforming device, including a reforming furnace (F101) and a reaction gas reforming system. The reaction gas reforming system includes a tubular reactor (R103), a shift reactor (R102), a gas-liquid separator, and a pressure swing adsorption hydrogen production system (Z101) connected in sequence. The reforming furnace (F101) includes a radiant section and a convection section. The tubular reactor (R103) is arranged in the radiant section. The tubular reactor (R103) has a raw material input end. The pressure swing adsorption hydrogen production system (Z101) has a hydrogen output end and a pressure swing adsorption tail gas output end. The radiant section has a fuel gas input end and an oxygen-rich gas input end. The convection section has a flue gas discharge end; A carbon dioxide separation system (Z102), connected to the pressure swing adsorption tail gas output end. The carbon dioxide separation system (Z102) has a carbon dioxide output end and a separated gas output end. The separated gas output end is connected to the fuel gas input end; A conversion gas heat exchanger group is arranged on the connecting pipeline between the tubular reactor (R103) and the shift reactor (R102). The conversion gas heat exchanger group at least includes a fuel gas / conversion gas heat exchanger (E105). The separated gas output from the separated gas output end is heated by the fuel gas / conversion gas heat exchanger (E105) and then enters the radiant section of the reforming furnace (F101) through the fuel gas input end; An air preheater (E115) is also arranged on the convection section. The oxygen-rich gas is preheated by the air preheater (E115) and then input into the radiant section through the oxygen-rich gas input end.

2. The natural gas steam reforming system according to claim 1, characterized in that The reaction gas reforming system further includes a steam generator, which is arranged on the convection section of the reforming furnace (F101). A steam drum (D101) is also connected to the steam generator. The steam drum (D101) includes a water input end, a water output end, a steam output end, and a steam input end. The steam output end is connected to the raw material input end. The steam input end is connected to the steam outlet of the steam generator.

3. The natural gas steam reforming system according to claim 2, wherein The steam generator includes a first steam generator (E114) having a first water inlet and a first steam outlet and a second steam generator (E111) having a second water inlet and a second steam outlet; The water output end is connected to the first water inlet of the first steam generator (E114) and the second water inlet of the second steam generator (E111). The first steam outlet is connected to the steam input end of the steam drum (D101); An deaerator (D102) is also connected to the water input end of the steam drum (D101). The second steam outlet of the second steam generator (E111) and / or the steam output end of the steam drum (D101) is connected to the deaerator (D102); The water in the deaerator (D102) enters the steam drum (D101) through the water input end after being deaerated.

4. The natural gas steam reforming system according to claim 3, wherein An air preheater (E112) and a steam superheater (E113) are also provided on the convection section; the steam output from the steam output end is mixed with the raw materials after heat exchange in the steam superheater (E113) to form raw material gas, and the raw material gas is input into the tubular reactor (R103) through the raw material input end after heat exchange in the raw material gas preheater (E112).

5. The natural gas steam reforming system according to claim 4, wherein a second steam generator (E111), a raw material gas preheater (E112), a steam superheater (E113), a first steam generator (E114), and an air preheater (E115) are sequentially arranged on the convection section along the conveying direction of the flue gas.

6. The natural gas steam reforming system according to any one of claims 3-5, wherein a conversion gas heat exchanger group is provided on the connecting pipeline between the conversion reactor (R102) and the gas-liquid separator; the conversion gas heat exchanger group includes at least a raw material gas / conversion gas heat exchanger. There are two raw material gas / conversion gas heat exchangers, namely a raw material gas / conversion gas heat exchanger I (E102) and a raw material gas / conversion gas heat exchanger II (E103); the conversion gas heat exchanger group also includes a raw material gas / conversion gas heat exchanger (E101); the raw materials are sequentially input into the raw material input end of the tubular reactor (R103) after heat exchange in the raw material gas / conversion gas heat exchanger (E101), the raw material gas / conversion gas heat exchanger I (E102), and the raw material gas / conversion gas heat exchanger II (E103).

7. The natural gas steam reforming system according to claim 6, wherein the conversion gas heat exchanger group also includes a conversion gas waste heat boiler (E104), the water in the steam drum (D101) is input into the conversion gas waste heat boiler (E104) for heat exchange with the conversion gas and then returns to the steam drum (D101); the conversion gas waste heat boiler (E104), the fuel gas / conversion gas heat exchanger (E105), and the raw material gas / conversion gas heat exchanger (E101) in the conversion gas heat exchanger group are sequentially arranged along the conveying direction of the conversion gas; and / or, the reaction gas reforming system further includes a desulfurization / hydrogenation reactor (R101), and the desulfurization / hydrogenation reactor (R101) is connected to the raw material outlet of the raw material gas / conversion gas heat exchanger II (E103); and / or, the liquid output end of the gas-liquid separator is communicated with a deaerator (D102); and / or, a demineralized water input end is also provided on the deaerator (D102); and / or, the conversion gas heat exchanger group also includes a deaerated water / conversion gas heat exchanger (E106); the water output from the deaerator (D102) enters the deaerated water / conversion gas heat exchanger (E106) for heat exchange with the conversion gas and then enters the steam drum (D101) through the water input end.

8. The natural gas steam reforming system according to claim 7, wherein The demineralized water / converted gas heat exchanger (E107) is also included in the converted gas heat exchanger group. After heat exchange through the demineralized water / converted gas heat exchanger (E107), the demineralized water enters the deaerator (D102) through the demineralized water input end. The raw material gas / converted gas heat exchanger II (E103), the deaerated water / converted gas heat exchanger (E106), the raw material gas / converted gas heat exchanger I (E102), and the demineralized water / converted gas heat exchanger (E107) in the converted gas heat exchanger group are arranged in sequence along the conveying direction of the converted gas.

9. The natural gas steam reforming system according to claim 8, characterized in that, There are two groups of the gas-liquid separators, namely the gas-liquid separator I (V101) and the gas-liquid separator II (V102) arranged in series. A converted gas final cooler (E108) is also arranged between the gas-liquid separator I (V101) and the gas-liquid separator II (V102).

10. A natural gas steam reforming process, characterized in that it is processed by using the natural gas steam reforming system described in claims 1-9.

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