Method and device for hydrogen production with low carbon dioxide levels

Abstract

The invention relates to a method and a device for producing a carbon monoxide-free make-up gas (15) consisting largely of hydrogen and nitrogen for an ammonia synthesis, wherein a hydrocarbon-containing feed (1) is converted by reforming (B) and water-gas shift (G) to a carbon monoxide-containing synthesis gas (6) consisting largely of hydrogen and carbon dioxide, from which carbon dioxide (7) is separated to give raw hydrogen (8), at least a portion of which is processed to form a feed (cryo-feed) (10) for a cryogenic gas separation (K) in which the cryo-feed (10) is separated into a hydrogen-rich, carbon monoxide-free first gas fraction (11), which is conducted onward as make-up gas or is supplemented with nitrogen (14) to form the make-up gas (15), and a hydrogen-rich second gas fraction with a low carbon level, which is used as fuel gas (13) for generation of process heat. The characterizing feature here is that the hydrogen-rich second gas fraction (13) with a low carbon level is obtained in the cryogenic gas separation (K) with a carbon content that is lower than that of the cryo-feed (10) and higher than that of the hydrogen-rich, carbon monoxide-free first gas fraction (11).

Description

[0001] Description

[0002] Process and device for low-carbon hydrogen production

[0003] The invention relates to a process for producing a carbon monoxide-free make-up gas for ammonia synthesis, consisting largely of hydrogen and nitrogen, wherein a hydrocarbon-containing feed is converted by reforming and water gas shift to a synthesis gas consisting largely of hydrogen and carbon dioxide and containing carbon monoxide, from which raw hydrogen is produced by separating off carbon dioxide, at least a part of which is processed into a feed (cryogenic feed) for cryogenic gas separation, in which a hydrogen-rich, carbon monoxide-free first gas fraction is produced from the cryogenic feed, which is passed on as make-up gas or supplemented with nitrogen to form the make-up gas, and a hydrogen-rich and low-carbon second gas fraction is produced which is used as fuel gas to generate process heat.

[0004] The invention also relates to a device suitable for carrying out the method according to the invention.

[0005] Ammonia is one of the world's most widely produced chemicals. It serves primarily as a raw material for the production of fertilizers, but is also increasingly gaining importance as an energy source and hydrogen storage medium. On an industrial scale, it is synthesized almost exclusively from nitrogen and hydrogen using the Haber-Bosch process. While hydrogen and nitrogen are still predominantly produced today with the formation and release of large amounts of climate-damaging carbon dioxide, there are increasing efforts to dispose of the resulting carbon dioxide through sequestration or material utilization rather than releasing it into the atmosphere.

[0006] In the Haber-Bosch process, an ammonia synthesis gas consisting primarily of hydrogen and nitrogen, in which the two substances are present in the stoichiometric ratio of 3:1 for ammonia synthesis, is fed into an ammonia synthesis reactor at a pressure between 100 and 200 bar. With catalytic support, it is exothermically converted to ammonia in an ammonia reactor. Due to thermodynamic limitations, however, the conversion is incomplete, resulting in a gas mixture that contains significant amounts of hydrogen and nitrogen in addition to ammonia.This gas mixture leaves the ammonia reactor at a temperature between 400 and 450°C and is subsequently cooled in a series of heat exchangers to separate ammonia by condensation and to obtain a recycle gas consisting largely of hydrogen and nitrogen, containing residues of non-separated ammonia. This recycle gas is returned to the ammonia reactor in a synthesis cycle to increase the ammonia yield and is mixed with a make-up gas to form ammonia synthesis gas.

[0007] According to the state of the art, to produce a make-up gas for ammonia synthesis, a hydrocarbon-containing feedstock, such as natural gas, is desulfurized if necessary and then reformed, for example, by partial oxidation, autothermal, or steam reforming, into a synthesis gas consisting largely of hydrogen, carbon monoxide, and carbon dioxide. This gas also contains significant amounts of argon, especially when reforming is carried out using atmospheric oxygen. The synthesis gas is then subjected to a water-gas shift to convert the contained carbon monoxide with water to hydrogen and carbon dioxide, thereby producing a synthesis gas.Carbon dioxide is usually separated from the synthesis gas by acid gas scrubbing, obtaining a carbon dioxide fraction with a purity sufficient for its sequestration or material use and a hydrogen fraction known as raw hydrogen, which, in addition to hydrogen, also includes residues of carbon monoxide, carbon dioxide and methane and possibly argon.

[0008] To prevent carbon monoxide from entering the ammonia reactor via the make-up gas and poisoning the catalyst material used there, the raw hydrogen is treated according to the state of the art by methanation, pressure swing adsorption or a cryogenic process, whereby carbon monoxide is converted or separated and a hydrogen fraction is produced which is referred to as carbon monoxide-free due to its low carbon monoxide content, typically below 10 ppmv, and at least a portion of which is passed on as make-up gas or supplemented with nitrogen to form the make-up gas.

[0009] Acid gas scrubbers, such as those used to separate carbon dioxide from synthesis gas, exploit the ability of liquids to selectively absorb carbon dioxide and other acid gases from a gas mixture and retain them in solution. The higher the pressure at which the scrubbing is carried out, the better the acid gases are absorbed and separated from the gas mixture to be purified. Since the synthesis gas in the water-gas shift process is produced at a pressure level typically between 25 and 45 bar(a), the volume flows to be treated are small, allowing carbon dioxide to be separated from the synthesis gas by acid gas scrubbing with comparatively low investment and operating costs.

[0010] Carbon dioxide is also present in flue gases produced during synthesis gas production in reformers and in furnaces used to heat feedstocks, which typically burn natural gas and / or carbon-containing residual gases. Unlike synthesis gas, these flue gases are pressureless. Because they can therefore only be treated very costly and laboriously using acid gas scrubbing or other carbon dioxide separation processes, they are usually released into the atmosphere along with the carbon dioxide produced during combustion.

[0011] Therefore, using the methods described, no more than 90% of the carbon used to produce the makeup gas can be captured in the form of carbon dioxide and disposed of through sequestration or recycled. Depending on legal requirements and penalties for carbon dioxide emissions, it may be advantageous to achieve higher carbon capture rates.

[0012] One possibility for increasing the carbon capture rate is described in patent application EP4328176A1, which proposes processing raw hydrogen using cryogenic gas separation to produce a hydrogen-rich, carbon monoxide-free gas fraction. A first portion of this gas is used as a make-up gas or supplemented with nitrogen to form a make-up gas, and a second portion is used as a fuel gas, the combustion of which does not produce carbon dioxide. The disadvantage of this approach, however, is that part of the complex, hydrogen-rich, carbon monoxide-free gas fraction cannot be converted into ammonia.

[0013] The object of the invention is to provide a method of the generic type and a device for carrying it out, which make it possible to produce a make-up gas for ammonia synthesis with reduced carbon dioxide release, but without the described disadvantages of the prior art.

[0014] The stated object is achieved according to the invention in that the hydrogen-rich and carbon-poor second gas fraction is obtained during the cryogenic gas separation with a carbon content which is lower than that of the cryogenic feed and higher than that of the hydrogen-rich, carbon monoxide-free first gas fraction.

[0015] Preferably, the cryogenic gas separation comprises a nitrogen scrubbing step, in which at least a portion of the cryogenic feedstock, cooled against process streams to be heated, is scrubbed in a column with the aid of imported high-pressure nitrogen, which is obtained, for example, in gaseous form from an air separator and also cooled and liquefied against process streams to be heated. This scrubbing step separates, in particular, carbon monoxide, but also other undesirable substances in the make-up gas, such as carbon dioxide, methane, and argon. The cryogenic feedstock or a separated portion of the cryogenic feedstock is introduced in gaseous form into the lower region of the scrubbing column, where, on its upward path, it is intensively contacted via mass exchange elements with the nitrogen supplied in liquid form at the top of the scrubbing column.The nitrogen becomes enriched with undesirable substances on its downward flow, while the content of undesirable substances in the countercurrent gas phase continuously decreases, so that the purified gas fraction withdrawn from the top of the scrubbing column consists primarily of hydrogen and nitrogen and contains only a non-critical amount of carbon monoxide, which is harmful to the ammonia synthesis catalyst. This top gas, which can therefore be described as carbon monoxide-free, is warmed against process streams that need to be cooled and, if necessary, enriched with nitrogen to achieve the required composition for the make-up gas.

[0016] In a preferred variant of the process according to the invention, in addition to the hydrogen-rich, carbon monoxide-free overhead gas, a hydrogen-rich and low-carbon gas fraction with a carbon content lower than that of the cryogenic feed and higher than that of the overhead gas is withdrawn from the scrubbing column via a side draw and, after heating, used as fuel gas against process streams to be cooled. Unlike in EP4328176A1, only a portion of the cryogenic feed fed to the scrubbing column is subjected to a complete scrub with liquid nitrogen, while the gas fraction provided as fuel gas is obtained by only an incomplete scrub. The nitrogen scrubbing can therefore be carried out with a smaller amount of scrubbing agent compared to the prior art.Particularly when the hydrogen-rich and carbon-poor gas fraction is removed below the topmost mass transfer element of the scrubbing column, the saved nitrogen leads to a significant improvement in efficiency. The choice of side draw position allows the carbon content of the fuel gas to be adjusted to achieve a specified carbon removal rate with minimal investment and operating costs.

[0017] During nitrogen scrubbing, in addition to the undesirable substances in the make-up gas, a portion of the hydrogen contained in the cryogenic feed is inevitably co-absorbed. To recover this hydrogen, at least a portion of the nitrogen laden with the components separated from the cryogenic feed can be withdrawn from the bottom of the scrubbing column and expanded into a separator known as a column bottom separator, where it is separated into a hydrogen-rich, low-carbon gas fraction and a liquid fraction containing the majority of the carbon separated from the cryogenic feed. One embodiment of the process according to the invention provides for the use of at least a portion of the hydrogen-rich, low-carbon gas fraction obtained in the column bottom separator as fuel gas.

[0018] Particularly when the cryogenic feed contains methane, the invention provides for cooling the cryogenic feed during cryogenic gas separation to such an extent that most of the methane it contains condenses out. The resulting two-phase mixture of substances is separated in a separator arranged upstream of the nitrogen scrubber and referred to as a column feed separator, producing a methane-rich liquid fraction and a hydrogen-rich and carbon-poor gas fraction containing a portion of the carbon monoxide present in the cryogenic feed and possibly argon. A first portion of the hydrogen-rich gas fraction, which is depleted in carbon content compared to the cryogenic feed, is discharged from the column feed separator and subjected to scrubbing with liquid nitrogen, while a second portion of the hydrogen-rich and carbon-poor gas fraction, after being warmed against process streams to be cooled, is used as fuel gas.

[0019] Each of the fuel gases produced according to the invention can be combusted either alone or together with one or more other hydrogen-rich and carbon-poor gas fractions obtained in the cryogenic gas separation to generate process heat.

[0020] To avoid blockages caused by freezing water in cryogenic gas separation, the preparation of raw hydrogen for cryogenic use includes a drying step in which water is removed from the possibly pretreated raw hydrogen, preferably by adsorptive means. The regeneration of the adsorbers loaded with water in the drying step is carried out using an anhydrous regeneration gas. According to the invention, an anhydrous gas from cryogenic gas separation is used as the regeneration gas. This gas is obtained by evaporation and heating against process streams to be cooled from at least a portion of the bottom product formed during nitrogen scrubbing and / or at least a portion of the liquid phases obtained in the column bottom separator and / or in the column feed separator.Since each of these gases contains carbon, at least parts of them can be recycled after use as regeneration gas to improve the carbon removal rate of the process or directly recycled and used in the reforming.

[0021] When processed for cryogenic use, the raw hydrogen can be subjected to methanation upstream of the drying step, whereby the carbon monoxide and carbon dioxide contained in the raw hydrogen are converted with hydrogen into water and methane.

[0022] The fuel gas produced according to the invention is preferably used to preheat a feedstock for reforming and / or to provide heat for the reforming reaction and / or to produce or superheat process steam. The process according to the invention can be used particularly advantageously in the production of "blue" ammonia, with the aim of disposing of the carbon dioxide generated during the production of the make-up gas as completely as possible through sequestration or material utilization.

[0023] Furthermore, the invention relates to a device for producing a carbon monoxide-free make-up gas for ammonia synthesis, consisting largely of hydrogen and nitrogen, with a reforming device in which a hydrocarbon-containing feed can be converted in order to obtain a synthesis raw gas containing hydrogen, carbon monoxide and carbon dioxide, a water gas shift and a carbon dioxide separation, with the aid of which a hydrogen-rich fraction comprising carbon monoxide residues, referred to as raw hydrogen, can be produced from the synthesis raw gas, a processing device with which at least a part of the raw hydrogen can be processed into a hydrogen-rich feed gas containing carbon compounds (cryogenic feed) for a cryogenic gas separation unit, and a cryogenic gas separation unit with which a hydrogen-rich,a carbon monoxide-free first gas fraction and a hydrogen-rich and carbon-poor second gas fraction can be formed, whereby the first gas fraction can be passed on as make-up gas or supplemented with nitrogen to form the make-up gas, and the second gas fraction can be used as fuel gas to generate process heat.

[0024] In terms of the device, the stated task is solved in that the cryogenic gas separator is designed to produce a hydrogen-rich and carbon-poor second gas fraction as fuel gas, the carbon content of which is lower than that of the cryogenic feed and higher than that of the hydrogen-rich, carbon monoxide-free first gas fraction.

[0025] In a preferred embodiment of the device according to the invention, the cryogenic gas separation device comprises a scrubbing column with mass transfer elements, in which at least a portion of the cryogenic feed can be scrubbed with liquid nitrogen to remove carbon monoxide, with the hydrogen-rich, carbon monoxide-free first gas fraction being withdrawn from the top of the scrubbing column. Particularly preferably, the scrubbing column is designed with a side draw, through which a hydrogen-rich and carbon-poor second gas fraction can be removed as fuel gas. The side draw is advantageously located between the lowest and highest mass transfer elements of the scrubbing column.

[0026] In a further embodiment of the device according to the invention, the cryogenic gas separation device comprises a separator connected to the scrubbing column, referred to as a column bottom separator, into which at least a portion of the nitrogen loaded with separated components in the scrubbing column can be expanded in order to be separated into a liquid phase enriched with carbon compounds and a hydrogen-rich and carbon-poor gas phase, at least a portion of which can be withdrawn as fuel gas.

[0027] In another embodiment of the device according to the invention, the cryogenic gas separator is designed to form a two-phase mixture of substances from at least a portion of the cryogenic feed by cooling and to separate it in a separator connected to the wash column, referred to as a column feed separator, into a liquid phase enriched with carbon compounds and a hydrogen-rich and carbon-poor gas phase, of which a first portion can be fed to the wash column for washing with liquid nitrogen and a second portion can be withdrawn as fuel gas.

[0028] The treatment device of the device according to the invention preferably comprises an adsorptive gas dryer, with which water can be separated from the optionally pretreated raw hydrogen to obtain a dry cryogenic feed. The adsorptive gas dryer is expediently connected to the cryogenic gas separator in such a way that a gas obtainable in anhydrous form in the cryogenic gas separator can be supplied to it as regeneration gas. The connection is preferably designed such that at least a portion of the bottom product obtained during the nitrogen scrubbing and / or at least a portion of the liquid phases obtainable in the column bottom separator and / or in the column feed separator can be used as regeneration gas after heating and evaporation against process streams to be cooled.Since each of these gases contains carbon, the device according to the invention advantageously has a connection via which at least a part of one of these gases can be recycled after its use as regeneration gas or directly and used in the reforming.

[0029] The treatment facility may further comprise a methanation reactor arranged upstream of the gas dryer, with which the raw hydrogen can be subjected to methanation.

[0030] Embodiments of the device according to the invention further provide a burner-fired furnace designed to preheat a feedstock for reforming or to provide heat for the reforming reaction or to produce or superheat process steam, in which a fuel gas that can be produced according to the invention can be burned.

[0031] In the following, the invention will be explained in more detail with reference to two embodiments shown schematically in Figures 1 and 2.

[0032] Figure 1 shows a preferred variant of a device according to the invention for generating a make-up gas for ammonia synthesis.

[0033] Figure 2 shows a cryogenic gas separation which can be used particularly advantageously for the production of the make-up gas according to the invention.

[0034] In Figure 1, a hydrocarbon-containing feed 1, which is for example natural gas, is fed to a desulfurization device A in order to obtain a desulfurized hydrocarbon-containing feed 2, which is converted in the reforming device B using oxygen 3, which is obtained from air 4 in an air separator F, for example by partial oxidation or autothermal reforming, into a synthesis raw gas 5 containing hydrogen, carbon monoxide, carbon dioxide, methane and argon. To increase the hydrogen content, the synthesis raw gas 5 is subjected to a water gas conversion G, in which carbon monoxide reacts with water to form hydrogen and carbon dioxide, and a low-carbon monoxide gas fraction 6 is produced, from which the majority of the carbon dioxide is removed in a sour gas scrubber H.The removed carbon dioxide 7 is sequestered or used for material purposes, while the remaining gas fraction 8, which is rich in hydrogen and contains carbon monoxide and is referred to as raw hydrogen, is passed on to the processing facility M, where it is converted into the hydrogen-rich cryogenic feed 10 containing methane and argon using a preferably adsorptive gas dryer L. Optionally, the raw hydrogen 8 can be subjected to methanation J in the processing facility M, in which carbon monoxide and carbon dioxide are converted with hydrogen to methane, producing a gas mixture 9 largely free of carbon monoxide and carbon dioxide for further feeding to the gas dryer L.In the cryogenic gas separator K, at least one hydrogen-rich, carbon monoxide-free gas fraction 11, a methane-rich, argon- and nitrogen-poor residual gas 12 and a hydrogen-rich and carbon-poor gas fraction 13 are obtained from the cryogenic feed 10, the carbon content of which is lower than that of the cryogenic feed 10 and higher than that of the hydrogen-rich, carbon monoxide-free gas fraction 11. While the hydrogen-rich, carbon monoxide-free gas fraction 11 is supplemented with nitrogen 14 to form the make-up gas 15 for ammonia synthesis (not shown) and the methane-rich, argon- and nitrogen-poor residual gas 12 is returned to the reforming device B via the compressor P, the hydrogen-rich and carbon-poor gas fraction 13 is fed as fuel gas to a furnace O used in the reforming device B to heat the hydrocarbon-containing feed 2 and is burned to form a largely carbon dioxide-free flue gas 16.

[0035] In the cryogenic gas separation unit K shown in Figure 2, arranged in a cold box C, the cryogenic feed 10 is cooled in the heat exchangers E1 and E2 to such an extent that the methane it contains condenses almost completely. The two-phase mixture 20 formed during cooling is separated in the column feed separator D1 into a methane-rich liquid phase 21 and a hydrogen-rich and carbon-poor gas phase 22, which also contains the majority of the argon and carbon monoxide present in the cryogenic feed 10. The majority of the hydrogen-rich and carbon-poor gas phase 22 is introduced into the lower section of the scrubbing column W via line 23.

[0036] Nitrogen, which is drawn in gaseous form at elevated pressure from the air separator F, is introduced into the cold box C via line 26, where cooling in the heat exchangers E1 and E2 produces the liquid nitrogen stream 27, the majority of which is expanded via valve b as scrubbing nitrogen 28 to the top of the scrubbing column W. The hydrogen-rich gas phase 23 is conducted upward in the scrubbing column W and brought into intensive contact with the scrubbing nitrogen 28, whereby in particular the carbon monoxide contained therein, as well as methane residues and a large portion of the argon present in the cryogenic feed 10, are scrubbed out and pass into the bottoms fraction. The top stream 11 of the scrubbing column W is a hydrogen-rich and carbon monoxide-free gas fraction that contains nitrogen and is free of methane and argon. Although it meets the purity requirements for the make-up gas for ammonia synthesis, its nitrogen content is too low.Therefore, after a first warm-up step in heat exchanger E2, pre-cooled nitrogen 31 is added to the head stream 11 via valve c. After a second warm-up step in heat exchanger E1, a further amount of nitrogen 32 is added via valve d to obtain the make-up gas 15 with the required hydrogen / nitrogen ratio.

[0037] The bottoms fraction is withdrawn from the scrubbing column W via line 29 and expanded via the throttle device a into the column bottom separator D2, where it is separated into a liquid phase 40 consisting largely of nitrogen, carbon compounds, and argon, and a hydrogen-rich and carbon-poor gas phase 41. Together with the hydrogen-rich and carbon-poor gas fraction 42 obtained by incomplete nitrogen scrubbing, which is conducted from the scrubbing column W via a side takeoff and is passed on through line 13, and, after being warmed against process streams to be cooled, is released as fuel gas in the heat exchangers E1 and E2. In addition, a portion 24 of the hydrogen-rich and carbon-poor gas phase 22 from the column feed separator D1 can be mixed into the fuel gas 13 in a controlled manner via the valve h.

[0038] The methane-rich liquid phase 21 present at the pressure of the cryogenic feed 10 is withdrawn from the column feed separator D1 via the valve e and combined with a first portion 33 of the liquid phase 40 obtained in the column bottom separator D2, supplied via the valve f, to form the material stream 34 which, after evaporation and heating in the heat exchangers E2 and E1, forms the methane-rich and nitrogen-poor residual gas 12 which is returned before the reforming R. In order to prevent argon enrichment in the reformer circuit, a second portion 35 of the liquid phase 40 is withdrawn via the valve g and, after evaporation and heating in the heat exchangers E2 and E1, is discharged from the process as purge gas 43.

[0039] To compensate for cooling losses and to balance the cooling balance, liquid nitrogen 36 is introduced into the cold box C and supplemented by a portion 37 of the liquefied nitrogen 27 supplied via valve i to form the nitrogen stream 38, which, after evaporation and heating in the heat exchangers E2 and E1, is disposed of via line 39 or fed for further use.

Claims

Patent claims 1. A process for producing a carbon monoxide-free, largely hydrogen and nitrogen-containing make-up gas (15) for ammonia synthesis, wherein a hydrocarbon-containing feedstock (1) is converted by reforming (B) and water gas shift (G) into a synthesis gas (6) consisting largely of hydrogen and carbon dioxide and containing carbon monoxide, from which raw hydrogen (8) is produced by separating carbon dioxide (7), at least a portion of which is processed into a feedstock (cryogenic feedstock) (10) for cryogenic gas separation (K), in which a hydrogen-rich, carbon monoxide-free first gas fraction (11) is produced from the cryogenic feedstock (10), which is passed on as make-up gas or supplemented with nitrogen (14) to form make-up gas (15), and a hydrogen-rich and low-carbon second gas fraction is produced as fuel gas (13) for generating process heat, characterized in thatthat the hydrogen-rich and carbon-poor second gas fraction (13) is obtained during the cryogenic gas separation (K) with a carbon content which is lower than that of the cryogenic feed (10) and higher than that of the hydrogen-rich, carbon monoxide-free first gas fraction (11).

2. Process according to claim 1, characterized in that in the cryogenic gas separation (K) at least a part (23) of the cryogenic feed (10) is washed with liquid nitrogen (28) in a washing column (W) to separate carbon compounds, the hydrogen-rich, carbon monoxide-free gas fraction (30) being withdrawn from the top and a hydrogen-rich and carbon-poor gas fraction (42) being withdrawn as fuel gas (13) via a side take-off from the washing column (W).

3. Process according to claim 2, characterized in that a bottom fraction (29) containing nitrogen-rich and carbon compounds, obtainable in the washing column (W), is separated into a nitrogen-rich liquid phase (40) enriched with carbon compounds and a hydrogen-rich and carbon-poor gas phase (41), at least a part of which is withdrawn as fuel gas (13).

4. Method according to claim 2 or 3, characterized in that in the cryogenic gas separation (K) from at least a part of the cryogenic insert (10) by cooling, a two-phase mixture of substances (20) is formed, which is separated into a liquid phase (21) enriched with carbon compounds and a hydrogen-rich and carbon-poor gas phase (22), of which a first part (23) is subjected to washing with liquid nitrogen (28), while a second part (24) is withdrawn as fuel gas (13).

5. Method according to one of claims 1 to 4, characterized in that the raw hydrogen (8) for forming the cryogenic feedstock (10) is subjected to methanation (J) in order to convert carbon monoxide and carbon dioxide with hydrogen into methane and water.

6. Process according to one of claims 1 to 5, characterized in that at least one methane-rich liquid phase (34) obtained during the cryogenic gas separation (K) is fed, after evaporation and heating, wholly or partly to the reforming device (B) as feed.

7. Process according to one of claims 1 to 6, characterized in that the fuel gas (13) obtained in the cryogenic gas separation (K) is burned to heat a feedstock (2) intended for the reforming (B).

8. Apparatus for producing a carbon monoxide-free make-up gas (15) consisting largely of hydrogen and nitrogen for ammonia synthesis, comprising a reforming device (B) in which a hydrocarbon-containing feedstock (1) can be converted to obtain a synthesis raw gas (5) containing hydrogen, carbon monoxide and carbon dioxide, a water gas shift (G) and a carbon dioxide separation (H), with the aid of which a hydrogen-rich fraction comprising carbon monoxide residues, referred to as raw hydrogen (8), can be produced from the synthesis raw gas (5), a processing device (M) with which at least a portion of the raw hydrogen (8) can be processed to a hydrogen-rich feedstock gas (cryogenic feedstock) (10) containing carbon compounds for a cryogenic gas separation unit (K), and a cryogenic gas separation unit (K) with which a hydrogen-rich,carbon monoxide-free first gas fraction (11) and a hydrogen-rich and carbon-poor second gas fraction (13) can be formed, wherein the first gas fraction (11) can be passed on as make-up gas or supplemented with nitrogen (14) to form make-up gas (15), and the second gas fraction (13) can be used as fuel gas for producing, Process heat is usable, characterized in that the cryogenic gas separator (K) is designed to produce a hydrogen-rich and carbon-poor second gas fraction (13) as fuel gas, the carbon content of which is lower than that of the cryogenic feed (10) and higher than that of the hydrogen-rich, carbon monoxide-free first gas fraction (11).

9. Device according to claim 8, characterized in that the cryogenic gas separator (K) comprises a scrubbing column in which at least a part (23) of the cryogenic feed (10) can be subjected to a scrubbing with liquid nitrogen (28) to separate carbon compounds, wherein the hydrogen-rich, carbon monoxide-free first gas fraction (30) from the top and a hydrogen-rich and carbon-poor second gas fraction (42) can be withdrawn as fuel gas (13) via a side take-off from the scrubbing column (W).

10. Device according to claim 9, characterized in that the cryogenic gas separation unit (K) comprises a separator (D2) connected to the washing column (W) and referred to as a column bottom separator, into which at least part of the nitrogen (29) loaded with separated components in the washing column (W) can be expanded in order to be separated into a liquid phase (40) enriched with carbon compounds and a hydrogen-rich and carbon-poor gas phase (41), at least part of which can be withdrawn as fuel gas (13). 1 1. Device according to one of claims 9 or 10, characterized in that from at least a part of the cryogenic insert (10) in the cryogenic gas separator (K) a two-phase mixture of substances (20) can be formed by cooling, which mixture can be separated in a separator (20) referred to as a column insert separator and arranged in the cryogenic gas separator (K) into a liquid phase (21) enriched with carbon compounds and a hydrogen-rich and carbon-poor gas phase (22), of which a first part (23) can be fed to the scrubbing column (W) for scrubbing with liquid nitrogen (28) and a second part (24) can be withdrawn as fuel gas (13).

12. Device according to one of claims 8 to 11, characterized in that the processing device (M) comprises a methanation reactor (J) with which carbon dioxide and carbon monoxide present in the raw hydrogen (8) can be converted with hydrogen into methane and water.

13. Device according to one of claims 8 to 12, characterized in that the cryogenic gas separator (K) is connected to the reforming device (B) in such a way that a liquid phase (21, 40) comprising carbon compounds arising in the cryogenic gas separator (K) can be fed, after evaporation and heating, in whole or in part to the reforming device (B) as feed.

14. Device according to one of claims 8 to 13, characterized in that it comprises a furnace (O) in which a fuel gas (13) obtainable in the cryogenic gas separator (K) can be burned to heat a feedstock (2) that can be fed to the reforming device (B).

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