Hydrogen production process and apparatus

Abstract

A method and apparatus for the synthesis of hydrogen comprising a reforming section for the production of synthesis gas and a post-treatment section for the production of hydrogen wherein the reforming section comprises an autothermal reformer and a gas-heated reformer arranged in parallel wherein heat is transferred from the autothermal reformer to the gas-heated reformer, the post-treatment section comprises a hydrogen purification section for separating hydrogen from the tail gas, and the equipment further comprises a pipeline for recycling the tail gas back to the reforming section.

Description

Field of the Invention

[0001] The present invention belongs to the field of hydrogen synthesis. In particular, the present invention relates to a method and apparatus for producing hydrogen from natural gas (NG). Background Art

[0002] In most cases, the production of hydrogen starts with the production of syngas, which is obtained by processing a hydrocarbon feedstock in a reforming section comprising a prereformer reactor and an autothermal reformer or a steam reformer.

[0003] Syngas, also known as synthesis gas, is a gas mixture containing carbon monoxide CO, hydrogen H2 and small amounts of carbon dioxide CO2 and methane CH4.

[0004] In a hydrogen production plant, the syngas thus obtained is subjected to specific treatments, including water-gas shift conversion, in which CO is converted to CO2 and H2 in the presence of water, and hydrogen purification, in which hydrogen is separated from unreacted compounds such as CO, CO2 and CH4.

[0005] Hydrogen production equipment based on reforming technology is also equipped with one or more fired heaters, which are used to accomplish the thermal tasks of the equipment, such as heating the feed streams to the prereformer and autothermal reformer.

[0006] In the art, there is an increasing interest in minimizing the carbon dioxide emissions of hydrogen production equipment, especially considering the evolving regulations regarding greenhouse gas emissions.

[0007] There are several solutions available for reducing the carbon dioxide emissions of hydrogen production equipment, but the most common solution is to capture carbon dioxide from the syngas and store the separated CO2 underground.

[0008] Unfortunately, the carbon dioxide separated from the syngas only addresses a limited part of the total carbon dioxide emissions of the equipment. In practice, the CO2 emitted from the equipment is the sum of several components, including the CO2 produced by the chemical conversion of hydrocarbons to syngas, and also the CO2 produced by the operation of the auxiliary systems of the equipment, such as the fired heaters. The contribution of the latter is not negligible and is rarely considered in the prior art.

[0009] WO 2022 / 038089 A1, US2022 / 194789A1 and US2015 / 129806A1 disclose known methods and equipment comprising a hydrogen production section. Summary of the Invention

[0010] The present invention aims to overcome the above-mentioned drawbacks of the prior art. Specifically, the present invention aims to reduce the CO2 emissions of hydrogen production equipment.

[0011] Accordingly, one aspect of the present invention is an apparatus for synthesizing hydrogen according to claim 1.

[0012] The apparatus comprises a reforming section for producing syngas from the conversion of a hydrocarbon feedstock and a work-up section for separating carbon dioxide from the syngas and producing hydrogen.

[0013] A hydrocarbon feedstock is supplied to the reforming section, which is divided into a first feedstock portion and a second feedstock portion. The first feedstock portion is supplied to an autothermal reformer, while the second feedstock portion is supplied to a gas-heated reformer. The autothermal reformer and the gas-heated reformer are arranged in parallel, and heat is transferred from the autothermal reformer to the gas-heated reformer. The syngas output of the reforming section is processed in a work-up unit comprising a hydrogen purification unit.

[0014] The hydrogen purification unit outputs hydrogen with a purity greater than 95% and a tail gas containing unconverted carbon oxides such as CO, CO2 and methane. To address the CO2 emissions problem of the hydrogen production plant, a portion (preferably: the major portion) of the tail gas generated in the work-up unit is recycled as feed to the gas-heated reformer and / or the autothermal reformer.

[0015] Another aspect of the present invention is a method for synthesizing hydrogen according to the claims.

[0016] The present invention provides an efficient method for producing high-purity hydrogen from syngas while keeping the greenhouse gas (carbon dioxide or methane) emissions of the apparatus as low as possible.

[0017] The present invention has the following advantages.

[0018] Recycling of the tailstock upstream of the reforming section, i.e., recycling to the gas-heated reformer and / or the autothermal reformer, allows the hydrogen production plant to operate at a low steam / carbon ratio (S / C ratio), since it is no longer necessary to achieve a low slip of carbon monoxide and methane from the reforming section. More steam can be injected at the inlet of the water-gas shift section to increase the carbon monoxide conversion rate. Advantageously, the oxygen consumption of the autothermal reformer is reduced.

[0019] Another advantage of the present invention is that in the work-up section of the apparatus, i.e., in the carbon dioxide removal unit and the hydrogen purification unit, the carbon source generated in the process is eliminated. In the hydrogen purification unit, the tail gas is separated from the hydrogen, and then the separated tail gas is recycled as feed back to the reforming section to avoid carbon dioxide emissions.

[0020] In a preferred embodiment of the present invention, the prereformer is arranged upstream of the autothermal reformer and upstream of the gas heating reactor. The S / C ratio at the inlet of the prereformer is preferably maintained at a value not greater than 1.5, preferably including (being) 0.5 - 1.5, even more preferably including (being) 0.6 - 0.9 or 0.7 - 0.9, for example about 0.8. In addition, steam can also be injected at the inlet of the gas heating reformer so that the steam-to-carbon ratio is greater than 2, typically about 5.

[0021] In addition, additional steam can be injected upstream of the water gas shift section to achieve an oxygen-to-carbon ratio (O / C ratio) preferably in the range of 2.25 - 3, even more preferably between 2.25 - 2.5.

[0022] The possibility of operating at a low S / C ratio at the inlet of the prereformer and the provision of a gas heating reformer in parallel with the autothermal reformer allow the load of the flame heater used to supply steam as a heating source to the reforming section to be reduced by about 20%. And when an air separation unit (ASU) is used to supply oxygen to the autothermal reformer, the size of the ASU can be reduced by 8%.

[0023] In addition, when the heat generated by the autothermal reformer is used to heat the hydrocarbon feedstock converted in the gas heating reformer, the load of the flame heater can be further reduced by 20%.

[0024] The fact that the load of the flame heater is reduced results in a reduction in the carbon intensity of the present method and equipment.

[0025] In practice, the present invention enables the reduction of the load of the flame heater, the size of the ASU, and the recycling of most of the unconverted carbon back into the process. Generally speaking, the CO2 emissions of the equipment are reduced and the efficiency of the equipment is improved. In addition, due to the reduction in the size of the ASU and the flame heater, the capital expenditure of the equipment is also reduced.

[0026] According to another advantageous aspect of the equipment and method of the present invention, the recycle of the tail gas as a feed to the gas heating reformer and / or the autothermal reformer, the parallel arrangement of the autothermal reformer and the gas heating reformer, and the intimate mixing of the synthesis gas stream carried out in the latter allow for a high conversion rate of the hydrocarbon feedstock without the drawback of increased carbon dioxide emissions.

[0027] These advantages are particularly evident when the ATR operates at a low S / C ratio (for example, including (being) 0.7 - 0.9). These S / C ratios are not used in a once-through system equipped with a primary reformer and an ATR in series, which requires a higher S / C ratio (2 - 4) and results in a consequent higher carbon intensity.

[0028] Due to the present invention, high-purity hydrogen is produced, and the carbon intensity of the process can be reduced to the desired value of 0.1 kg CO2 / kgH2. Description of the Invention

[0029] The hydrogen production equipment includes a reforming section configured to convert a hydrocarbon feedstock into syngas. Preferably, the hydrocarbon feedstock is natural gas.

[0030] The reforming section includes an autothermal reformer and a gas-heated reformer arranged in parallel. The autothermal reformer is arranged to receive a first feedstock portion of the hydrocarbon feedstock to produce a first syngas stream under autothermal reforming conditions.

[0031] The gas-heated reformer has a reaction vessel. The gas-heated reformer includes a first side and a second side, wherein the first side is arranged to receive a second portion of the hydrocarbon feedstock. The first side may contain a catalyst for converting the feedstock into syngas. The first side may be the tube side of the gas-heated reformer, which may include a catalyst to produce a second syngas stream. The second side of the gas-heated reformer may be the shell side of the reformer, and the shell side may be arranged to surround the tube side.

[0032] The first side and the second side are arranged such that the fluid passing through the first side can exchange heat with the fluid passing through the second side. In particular, during operation, heat is transferred from the fluid on the second side (hot side) to the fluid on the first side. The first side is in fluid communication with the second side such that the syngas effluent from the first side enters the second side. The second side of the reformer and the syngas effluent from the first side are supplied together to the syngas output of the autothermal reforming section to be mixed with the syngas of the latter, thereby producing a combined syngas on the second side. The combined syngas is the output of the reforming section of the equipment.

[0033] Then, the syngas output of the reforming section is processed in a post-treatment section, which includes a water-gas shift reactor, a carbon dioxide removal unit, and a hydrogen purification unit. The hydrogen purification unit is arranged to separate hydrogen from the tail gas containing unconverted carbon oxides (such as CO, CO2, and CH4).

[0034] The equipment further includes at least one pipeline arranged to recycle the tail gas as a feed to the gas-heated reformer and / or as a feed to the autothermal reformer.

[0035] The hydrogen produced by the equipment has a high purity, preferably higher than 95%, more preferably higher than 99%. The hydrogen can be used as a reagent for ammonia and / or methanol synthesis. According to one embodiment, the hydrogen production equipment of the present invention can be integrated with an ammonia production equipment and / or a methanol production equipment or both.

[0036] According to a particularly interesting embodiment of the present invention, the reforming section further includes a pre-reformer, which is arranged upstream of the autothermal reformer and upstream of the gas-heated reformer. Thus, the autothermal reformer and the gas-heated reformer are supplied with partially reformed gas, which includes unconverted hydrocarbons, i.e., methane.

[0037] The apparatus may also be integrated with a desulfurization unit and / or a natural gas purification unit, which are arranged upstream of the pre-reformer and are used to remove sulfur and / or other possible catalyst poisons from the hydrocarbon feedstock supplied to the pre-reformer. The desulfurization unit is preferably a catalytic reactor.

[0038] The apparatus may further include a recycle line, which is arranged to recycle at least a portion of the tail gas extracted from the hydrogen separator unit upstream of the desulfurization unit.

[0039] Preferably, the hydrogen purification unit is one of the following: a pressure swing adsorption unit, a cryogenic separation unit, or a membrane separator, preferably a pressure swing adsorption unit.

[0040] The apparatus preferably further includes an air separation unit ASU, which is arranged to supply oxygen to the autothermal reformer. Preferably, the autothermal reformer is an oxy-fuel autothermal reformer.

[0041] The apparatus may further include a first heat exchanger arranged upstream of the pre-reformer and / or a second heat exchanger arranged upstream of the gas-heated reformer. The first heat exchanger and the second heat exchanger can be used to preheat the feedstock portion of the hydrocarbon feedstock supplied to the reformer. The load required for such heat exchangers is provided by the hot fluid leaving the hot side of the gas-heated reformer, and then such gas is supplied to the heat recovery section.

[0042] According to a particularly interesting use, the apparatus further includes a heat recovery section arranged downstream of the reforming section and upstream of the post-treatment section. The heat recovery section may include a waste heat boiler, which is arranged to recover heat from the syngas output of the reforming section that generates steam as a by-product.

[0043] The steam generated can be used to partially satisfy the heat load of the apparatus, or alternatively, the steam generated can be further superheated in a fired heater and then used as a processing medium for power generation in the apparatus, such as in a steam turbine.

[0044] The apparatus preferably includes one or more fired heaters for satisfying the heat load of the apparatus. The fired heaters can be used to supply heat to the feed streams of the hydrodesulfurization reactor, the pre-reformer, the gas-heated reformer, and the autothermal reformer, and to superheat the steam generated in the heat recovery section.

[0045] In some embodiments, the apparatus further includes a falling film saturator disposed downstream of the waste heat boiler, the falling film saturator being configured to supply all or part of the process steam to the prereformer. The falling film saturator is configured to evaporate process condensate, or fresh water, or process condensate and fresh water. More precisely, in the falling film saturator, the natural gas stream enters from below and the liquid water enters from above, forming a film within the plurality of tubes of the saturator. The hot effluent stream from the GHR provides (preferably after passing through the waste heat boiler) the heat required to evaporate water in the tubes in order to produce a water-saturated stream.

[0046] Another object of the present invention is a method for producing hydrogen. The method includes providing a hydrocarbon feedstock and dividing the hydrocarbon feedstock into a first feedstock portion and a second feedstock portion.

[0047] The method includes subjecting the hydrocarbon feedstock to a reforming process to produce syngas. The reforming process includes an autothermal reforming step and a gas heated reforming step carried out in parallel.

[0048] The autothermal reforming step is carried out on the first feedstock portion and the gas heated reforming step is carried out on the second feedstock portion. Heat is transferred from the autothermal reforming step to the gas heated reforming step.

[0049] According to the present invention, the syngas output of the autothermal reforming step is mixed with the syngas output on the first side of the gas heated reforming step to produce a combined syngas stream. The heat transfer from the ATR to the gas heated reformer is achieved by allowing the combined syngas to flow on the second side of the gas heated reformer.

[0050] Preferably, the shell side of the gas heated reformer surrounds the tube side of the reformer such that when the combined syngas passes through the second side of the reformer, heat is transferred from the combined syngas to the first portion of hydrocarbons undergoing reforming on the first side of the gas heated reforming.

[0051] The method further includes a post-treatment process for the syngas output of the gas heated reforming step, the post-treatment process including a water gas shift conversion, a carbon dioxide removal step, and a hydrogen purification step.

[0052] The hydrogen purification step produces hydrogen and a tail gas containing carbon monoxide, carbon dioxide, and residual hydrogen. The tail gas is recycled as a feed to the gas heated reforming step and / or the autothermal reforming step.

[0053] According to a preferred embodiment, the first feedstock portion accounts for 80 vol% to 98 vol% of all the hydrocarbon feedstock processed in the reforming section.

[0054] According to a preferred embodiment, the amount of tail gas recycled as a feed to the gas heated reformer accounts for 10 vol% to 100 vol% of all the tail gas produced in the hydrogen purification step.

[0055] According to an embodiment of particular interest of the present invention, a hydrodesulfurization step and an adiabatic prereforming step are carried out before the reforming process. The adiabatic prereforming step is preferably carried out on the hydrocarbon feedstock that has been desulfurized.

[0056] Preferably, the output of the prereformer is a partially reformed gas containing unreacted hydrocarbons. The prereformed gas can then be split into a first gas stream and a second gas stream, and the first and second gas streams are then subjected to the reforming process described above.

[0057] Preferably, the steam-to-carbon ratio (S / C ratio) at the inlet of the adiabatic prereforming step is not greater than 1.5, preferably ranges from (is) 0.5 - 1.5, and even more preferably ranges from (is) 0.6 - 0.9 or 0.7 - 0.9, for example about 0.8. In addition, steam can also be injected at the inlet of the gas-heated reformer such that the steam-to-carbon ratio is greater than 2, typically about 5.

[0058] According to an embodiment of the present invention, a portion of the tail gas obtained from the hydrogen purification step is recycled upstream of the hydrodesulfurization step.

[0059] Preferably, the portion of the tail gas recycled upstream of the hydrodesulfurization step contains 1 vol% to 15 vol% of the tail gas generated in the hydrogen purification step.

[0060] The syngas output of the reforming section is preferably used to indirectly heat the hydrocarbon feedstock or supply the prereformed gas to the autothermal reformer and / or the gas-heated reformer.

[0061] In one embodiment, steam is injected upstream of the gas-heated reforming step such that the steam-to-carbon ratio at the inlet of the gas-heated reformer is greater than 2, preferably greater than 5.

[0062] In addition, additional steam can also be injected upstream of the water-gas shift section so that the O / C ratio is preferably in the range of 2.25 - 3 and even more preferably between 2.25 - 2.5.

[0063] According to a particularly interesting embodiment, about 90% of all the hydrocarbon feedstock processed in the reforming section of the plant is sent to the autothermal reformer step, and the remaining portion is sent to the gas-heated reformer step. Preferably, the steam-to-carbon ratio at the inlet of the preformer is less than 1, and more preferably about 0.8.

[0064] Preferably, about 90% of all the tail gas generated in the hydrogen purification step is recycled at the inlet of the ATR inlet, and the remaining portion is sent back to the desulfurization unit or the gas-heated reformer or both. In this way, the hydrogen content of the ATR feed is maximized, and carbon deposition and soot formation in the ATR are reduced.

[0065] In some embodiments, the hydrogen recovery unit can be placed after the water-gas shift reactor and upstream of the carbon dioxide recovery unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 An apparatus for synthesizing hydrogen according to a preferred embodiment of the present invention is shown.

[0067] Figure 2 The reforming section of the hydrogen production apparatus of the present invention is shown.

[0068] Figure 3 A schematic diagram of an apparatus for synthesizing hydrogen according to an embodiment of the present invention.

[0069] Figures 4 to 7 Different embodiments of the present invention are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070] Figure 1 An apparatus 100 for synthesizing hydrogen is shown, which includes a reforming section 101 and a post-treatment section 103.

[0071] The reforming section 101 includes a hydrodesulfurization reactor 2, a prereformer 4, an autothermal reformer ATR 7, and a gas-heated reformer GHR 11. The ATR 7 and the GHR 11 are arranged in parallel.

[0072] The post-treatment section 103 includes a water-gas shift reactor 14, a CO2 removal unit 16, and a pressure swing adsorption unit 20.

[0073] The apparatus operates as follows: A hydrocarbon feedstock 1 composed of natural gas is supplied to the hydrodesulfurization reactor 2 to produce a desulfurized natural gas stream 3. The desulfurized natural gas stream 3 is prereformed in the prereformer 4. The output of the prereformer 4 is a prereformed gas 5, which includes unreacted hydrocarbons such as methane. The prereformed gas 5 is divided into a first portion of the prereformed gas 6 and a second portion of the prereformed gas 10. Preferably, the first portion of the prereformed gas 6 is at least 90% of all the prereformed gas 5.

[0074] The first portion of the prereformed gas 6 is supplied to the ATR 7 together with an oxygen stream 8 generated in the air separation unit 9. The output of the ATR 7 is a first synthesis gas stream 12.

[0075] The second portion 10 of the prereformed gas is supplied to the GHR 11 in the tube side of the GHR to produce a second synthesis gas stream 26 (as Figure 2 shown). The second synthesis gas stream 26 is mixed with the first synthesis gas stream 12 in the shell side of the GHR 11 to obtain a syngas 13A.

[0076] On the second side of the GHR 11, the gas stream 13A exchanges heat with the second part of the pre-reformed gas 10 that is reformed on the reactor tube side. After the heat exchange, the gas stream 13A reaches the conditions of the gas stream 13 that is the output of the reforming section.

[0077] Then the syngas 13 is processed in the water gas shift reactor 14 to obtain a shifted gas 15 rich in hydrogen, which is then sent to the CO2 removal unit 16. The output of the CO2 removal unit 16 is a first carbon dioxide stream 18 that is recycled back to the hydrodesulfurization reactor 2, a second carbon dioxide stream 50 that is further sent for compression and storage underground, and a carbon dioxide-depleted gas stream 19 rich in hydrogen.

[0078] Then the carbon dioxide-depleted gas stream 19 is processed in the pressure swing adsorption unit 19 to produce a hydrogen gas stream 22 and a tail gas 21, and the tail gas 21 contains hydrogen, residual unreacted hydrocarbons such as methane and carbon monoxide.

[0079] Then a part of the tail gas 21 (preferably its main part; i.e., >95% by volume) can be recycled as a feed via the pipeline 30 to the gas heated reformer 11 and / or via the pipeline 31 to the autothermal reformer ATR, and in some embodiments, via the pipeline 32 to the hydrodesulfurization reactor 2. The remaining part of the tail gas 21 can be discharged from the system and used as fuel for a flame heater (not shown in the figure).

[0080] The device further includes a flame heater (not shown in the figure) that is used to supply heat to the hydrodesulfurization reactor 2, the pre-reformer 4, and the autothermal reformer 7 and / or superheat the steam generated by the process. The steam superheated by the flame heater can also be transported to a steam generator for power generation.

[0081] A part of the tail gas stream 21 and the hydrogen gas stream 22 can also be supplied to the flame heater.

[0082] Figure 2 The arrangement of the ATR 7 and the GHR 11 is shown in detail.

[0083] The first part of the hydrocarbon feedstock 6 is supplied to the autothermal reformer 7, or in a hydrogen production device 100 equipped with a pre-reformer, the first part of the pre-reformed gas is supplied to the ATR 7.

[0084] The output of the ATR is a first syngas stream 12, which is then supplied to the second side 25 of the gas heated reformer 11.

[0085] Conversely, either the second part of the hydrocarbon feedstock 10 is supplied to the gas heated reformer 11, or in a hydrogen production device 100 equipped with a pre-reformer 4, the second part of the pre-reformed gas is supplied to the GHR 11.

[0086] The second part of the hydrocarbon feedstock 10 reacts in the tube side of the reformer to produce a second synthesis gas stream 26. The latter is mixed with the first synthesis gas stream 12 to produce a combined synthesis gas 13A on the shell side of the reactor.

[0087] Note that the first synthesis gas stream 12 leaving the ATR 7 has a temperature of 850 °C to 1100 °C, and in the present invention, this gas is mixed with the gas stream 26 to produce a gas stream 13A having a temperature of 800 °C to 1050 °C. The gas stream 13A is used for heat exchange with the second part of the hydrocarbon feedstock 10 undergoing reforming in the tube side of the GHR 11. After heat exchange, the gas stream 13A is cooled to the temperature of the gas stream 13, which is the final output of the reforming section.

[0088] Figure 3 An embodiment of the present invention is shown, in which the apparatus further includes a heat recovery section 104, which includes a waste heat boiler WHB 34.

[0089] Note that the synthesis gas 13 output from the GHR 11 is cooled in the waste heat boiler 34 to generate steam. The steam generated in the WHB 34 can be used to meet the heat load of the apparatus.

[0090] Figure 4 Another embodiment of the present invention is shown, in which the apparatus 100 further includes a first heat exchanger 51 arranged before the pre-reformer 4. The heat exchanger 51 is used to preheat the pre-reforming mixed feed (3, 53) of gas and steam supplied to the pre-reformer 4. In this embodiment, the pre-reformer heating coil 40 may not be present.

[0091] Steam can also be injected upstream of the GHR 11 to adjust the S / C ratio at the inlet of the gas heating reformer 11.

[0092] Note that in this embodiment, the heat recovery section 104 for recovering heat from the synthesis gas 13 includes a waste heat boiler WHB 34 and a heat exchanger 51 for preheating the hydrocarbon feedstock 3 and steam 53.

[0093] The hydrocarbon feedstock 3 and steam 53 are mixed and preheated in the heat exchanger 51, and then can be further heated in the pre-reforming heat exchanger 40, and then react with the desulfurized gas stream 3 in the pre-reformer 4.

[0094] Figure 5 An embodiment is shown in which the synthesis gas 13 output from the GHR 11 is used to preheat the second part of the pre-reformed gas 10 in the heat exchanger 54. Note that steam 37, 56 can be added before the pre-reforming heat exchanger 40 and before the heat exchanger 54 to adjust the steam-to-carbon ratio. The GHR heating coil 36 may not be present in this embodiment.

[0095] Figure 6 shows a hydrogen production device integrating Figure 4 and Figure 5 the embodiment shown.

[0096] Figure 7 shows a device configuration, where the heat recovery section further includes a falling film saturator (FFS) heat exchanger 57; in the FFS heat exchanger 57, the desulfurized natural gas stream 3 contacts the water stream 60 to obtain a mixture containing steam and desulfurized natural gas; this mixture is heated by indirect heat exchange with the hot reformed syngas 13. Thus, the reformed syngas 13 sequentially passes through the FFS heat exchanger 57, transferring heat to the mixture of the water-containing 60 and the natural gas stream 3. The desulfurized hydrocarbon feedstock 3 and water 60 are supplied to the tube side of the FFS heat exchanger 57. This water 60 can be process condensate or fresh water. The effluent of the WHB 34 can be used to provide the heat required for the saturated gas stream 3 to generate the water-saturated gas stream 38. In order to achieve the required S / C ratio at the inlet of the prereformer 4, additional steam 56 can be added to the gas stream 38.

Claims

1. An apparatus (100) for producing hydrogen (22), comprising: A reforming section (101) configured to convert a hydrocarbon feedstock (5) into synthesis gas (13), wherein the reforming section (101) includes an autothermal reformer (7) and a gas-heated reformer (11) arranged in parallel, wherein: The autothermal reformer (7) is arranged to receive a first feedstock portion (6) of the hydrocarbon feedstock (5) and produce a first synthesis gas stream (12); The gas-heated reformer (11) includes a first side (24) and a second side (25), wherein the gas-heated reformer (11) is arranged to receive a second feedstock portion (10) of the hydrocarbon feedstock (5) at the first side (24) and produce a second synthesis gas stream (26) at the same side, and the first synthesis gas stream (12) and the second synthesis gas stream (26) are mixed at the second side (25) to produce the synthesis gas (13); A post-treatment section (103) of the synthesis gas (13), the post-treatment section (103) including a water-gas shift reactor (14), a carbon dioxide removal unit (16) and a hydrogen purification unit (20), the hydrogen purification unit (20) being arranged to separate hydrogen (22) from the tail gas (21); At least one pipeline (30, 31) arranged to recycle the tail gas (21) as a feed to the gas-heated reformer (11) and / or as a feed to the autothermal reformer (7).

2. The apparatus according to claim 1, wherein the reforming section (101) further includes a pre-reformer (4) arranged upstream of the autothermal reformer (7) and upstream of the gas-heated reformer (11).

3. The apparatus according to claim 2, further comprising a desulfurization unit (2) and a recycle pipeline (32), the desulfurization unit (2) being arranged upstream of the pre-reformer (4), and the recycle pipeline (32) being arranged upstream of the desulfurization unit (2) to recycle at least a portion of the tail gas (21).

4. The apparatus according to any one of the preceding claims, wherein the hydrogen purification unit (20) is one of: a pressure swing adsorption unit, a cryogenic separation unit or a membrane separator.

5. The apparatus according to any one of the preceding claims, wherein the gas-heated reformer (11) is a shell-and-tube reformer, wherein the first side (24) is the tube side and the second side (25) is the shell side.

6. The apparatus according to any one of the preceding claims, further comprising an air separation unit (9) arranged to supply an oxygen stream (8) to the autothermal reformer (7).

7. The apparatus according to any one of the preceding claims, further comprising a first heat exchanger (51) and / or a second heat exchanger (36), wherein the first heat exchanger (51) is arranged upstream of the prereformer (4) and is configured to preheat the hydrocarbon feedstock (3) and steam (53), and the second heat exchanger (36) is arranged upstream of the gas heating reactor (11) and is arranged to preheat the second feedstock portion (10) of the hydrocarbon feedstock (5).

8. The apparatus according to any one of the preceding claims, further comprising a heat recovery section (104), wherein the heat recovery section (104) is arranged downstream of the reforming section (101) and upstream of the post-treatment section (103), and the heat recovery section (104) includes a waste heat boiler (34) which is arranged to recover heat from the syngas (13) output of the reforming section (101).

9. The apparatus according to any one of the preceding claims, further comprising a falling film saturator (57), wherein the falling film saturator (57) is arranged downstream of the waste heat boiler (34) and is configured to supply all or part of the process steam to the prereformer, and the falling film saturator (57) is configured to evaporate process condensate, or fresh water, or process condensate and fresh water.

10. A method (100) for producing hydrogen (22), comprising the following steps: - providing a hydrocarbon feedstock (5) and dividing the hydrocarbon feedstock (5) into a first feedstock portion (6) and a second feedstock portion (10); - performing a reforming process (101) to produce syngas (13), wherein the reforming process includes an autothermal reforming step (7) and a gas heating reforming step (11) carried out in parallel, wherein the autothermal reforming step (7) is carried out on the first feedstock portion (6), the gas heating reforming step (11) is carried out on the second feedstock portion (10), and heat is transferred from the autothermal reforming step (7) to the gas heating reforming step (11); - performing post-treatment on the syngas (13), the post-treatment including a water gas shift conversion step (14), a carbon dioxide removal step (16) and a hydrogen purification step (21), wherein the hydrogen purification step (21) produces a hydrogen stream (22) and a tail gas (18) containing carbon monoxide, carbon dioxide and residual hydrogen; - recovering the tail gas (21) as a feed for at least one of the following steps: the gas heating reforming step (11) and / or the autothermal reforming step (7).

11. The method according to claim 10, wherein the first feedstock portion (6) contains 80 vol% to 98 vol% of the hydrocarbon feedstock (5).

12. The method according to claim 10 or 11, wherein the amount of the tail gas recycled as a feed to the gas heating reformer (11) is 10 vol% to 100 vol% of the tail gas (21) produced in the hydrogen purification step (20).

13. The method according to any one of the preceding claims 10 - 12, wherein the reforming process (101) is preceded by a hydrodesulfurization step (2) and an adiabatic prereforming step (4).

14. The method according to claim 13, wherein the steam - to - carbon ratio at the inlet of the adiabatic prereforming step (4) is not greater than 1.5, preferably comprises 0.5 - 1.5, or even more preferably comprises 0.6 - 0.9 or 0.7 - 0.9, for example about 0.

8.

15. The method according to any one of the preceding claims 10 - 14, wherein a portion (32) of the tail gas (21) is recycled upstream of the hydrodesulfurization step (2), preferably the portion (32) comprises 1 vol% to 15 vol% of the tail gas (21) produced in the hydrogen purification step (20).

16. The method according to any one of the preceding claims 10 - 15, further comprising indirectly transferring heat from the synthesis gas (13) output of the reforming process (101) to the first feedstock portion (6) and / or the second feedstock portion (10).

17. The method according to any one of the preceding claims 10 - 16, further comprising the step of injecting steam (37) upstream of the gas - heated reforming process (11) such that the steam - to - carbon ratio at the inlet of the gas - heated reformer is greater than 2, preferably greater than 5.

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