Plant and process for the synthesis of a hydrogen product, method of revamping

Abstract

The present invention relates to a process and plant (1) for the synthesis of a hydrogen product (10) Said plant comprises: a reforming section (2) configured to convert a hydrocarbon feedstock (3) into a raw synthesis gas (4); a post-treatment section (5) of said raw synthesis gas (4) comprising at least a water gas shift (WGS) conversion reactor (6), a liquid-gas separator (7), a carbon dioxide (CO2) removal unit (8), and a hydrogen purification section (9) providing said H2 product (10); wherein said liquid-gas separator (7) is configured for producing a process condensate (12), and wherein said CO2 removal unit (8) is arranged for separating a CO2- enriched stream (14); a stripping column (15) arranged for stripping said process condensate (12) with a stripping medium (16) to obtain a bottom stripped liquid (17) and a top waste stream (18); a washing column (20) arranged for washing said CO2-enriched stream (14) with at least a portion (44) of said bottom stripped liquid (17) thus obtaining a spent liquid (19) containing one or more by-product(s), such as ammonia and / or methanol, and a purified CO2 stream (21); and a line (22) for recycling at least part of said spent liquid (19) to the stripping column (15). The present invention further relates to a method of revamping a plant for the synthesis of a hydrogen product.

Description

[0001] “Plant and process for the synthesis of a hydrogen product, method of revamping

[0002] DESCRIPTION

[0003] Field of the invention

[0004] The invention is in the field of hydrogen or ammonia synthesis. The invention particularly pertains to a process and a plant for the synthesis of hydrogen from synthesis gas.

[0005] Prior art

[0006] In most cases, the production of hydrogen starts with the production of synthesis gas (syngas) which is obtained by treating a hydrocarbon feedstock in a reforming unit that may include an autothermal reformer or, as an alternative, a steam reformer.

[0007] Syngas is a gaseous mixture comprising carbon monoxide (CO), hydrogen (H2) and minor amounts of carbon dioxide (CO2) and methane (CPU).

[0008] In hydrogen plants, the syngas obtained from the reforming unit is subjected to dedicated treatments to increase a hydrogen content of the syngas, e.g. by converting CO to CO2 and / or by removing unconverted compounds.

[0009] So-called “blue hydrogen” is hydrogen produced in a process comprising reforming of natural gas as hydrocarbon feedstock, followed by carbon capture and storage (CCS) of the carbon dioxide obtained as a side product.

[0010] CCS is a necessary measure in view of an environmental need of reducing emissions of carbon dioxide that is one of the most widespread greenhouse gases.

[0011] Continuously evolving regulations may pose increasingly strict requirements also for the purity of captured and stored carbon dioxide in view of possible uses of CO2 as a reagent for downstream processes (e.g. for urea synthesis).

[0012] US 2015 / 315020 A1 belongs to the known art. The Applicant, after long and intensive research and development, has developed a plant and process that provide an adequate response to the existing limitations, drawbacks, and problems.

[0013] Therefore, the subject matter of the present invention is a plant and a process for the synthesis of a hydrogen-containing product, and a method of revamping a plant for the synthesis of a hydrogen product.

[0014] Summary of the invention

[0015] The purpose of the invention is to solve the aforementioned drawbacks of the known art.

[0016] In particular, the present invention comes from the ingenious insight of the inventor that at least a portion of a bottom stripped liquid of the post-treatment may be used for washing a CCh-enriched stream, whereby a spent washing liquid containing one or more by-product(s) can be recirculated to stripping for regenerating the liquid used for washing.

[0017] The present invention relates to a plant for the synthesis of a hydrogen (H2) product comprising:

[0018] - a reforming section configured to convert a hydrocarbon feedstock into a raw synthesis gas;

[0019] - a post-treatment section of said raw synthesis gas comprising at least a water gas shift (WGS) conversion reactor, a liquid-gas separator, a carbon dioxide (CO2) removal unit, and a hydrogen purification section providing said H2 product; wherein said liquid-gas separator is configured for producing a process condensate, and wherein said CO2 removal unit is arranged for separating a CO2-enriched stream;

[0020] - a stripping column arranged for stripping said process condensate with a stripping medium to obtain a bottom stripped liquid and a top waste stream;

[0021] - a washing column arranged for washing said CO2-enriched stream, optionally after compression, with at least a portion (e.g., only a portion) of said bottom stripped liquid thus obtaining a spent liquid containing one or more byproducts), such as ammonia and / or methanol, and a purified CO2 stream; a line for recycling at least part of said spent liquid to the stripping column.

[0022] Furthermore, the present invention relates to a process for the synthesis of a hydrogen (H2) product, said process comprising the following steps:

[0023] (I) reforming of a hydrocarbon feedstock into a raw synthesis gas;

[0024] (II) post-treatment of said raw synthesis gas comprising at least a water gas shift (WGS) conversion, a liquid-gas separation, a carbon dioxide (CO2) removal and a hydrogen purification; wherein said liquid-gas separation produces a process condensate, and wherein said CO2 removal is arranged for separating a CO2-enriched stream;

[0025] (III) stripping of said process condensate with a stripping medium to obtain a bottom stripped liquid and a top waste stream;

[0026] (IV) washing of said CO2-enriched stream, optionally after compression, with at least a portion (e.g., only a portion) of said bottom stripped liquid thus obtaining a spent liquid containing one or more by-product(s), such as ammonia and / or methanol, and a purified CO2 stream;

[0027] (V) recycling at least part of said spent liquid to said stripping of step (III).

[0028] Furthermore, the present invention relates to a method of revamping a plant for the synthesis of a hydrogen (H2) product, said plant to be revamped comprising at least:

[0029] - a reforming section;

[0030] - a water gas shift (WGS) conversion reactor, a liquid-gas separator, a carbon dioxide (CO2) removal unit, and a hydrogen purification section providing said H2 product; said method of revamping comprising: (A) if not already available, installing a stripping column arranged for stripping a process condensate produced by the liquid-gas separator with a stripping medium to obtain a bottom stripped liquid and a top waste stream;

[0031] (B) installing a washing column arranged for washing a CCh-enriched stream separated by the CO2 removal unit with at least a portion (e.g., only a portion) of said bottom stripped liquid thus obtaining a spent liquid containing one or more by-product(s), such as ammonia and / or methanol, and a purified CO2 stream;

[0032] (C) installing a line for recycling at least part of said spent liquid to the stripping column.

[0033] Advantageous effects of the invention

[0034] The invention has the following advantages.

[0035] Advantageously, the plant and process of the present invention makes use of a process condensate that is already available at a suitable pressure required by the stripping and washing steps or apparatuses, so that additional pumps or compressors are not required.

[0036] Advantageously, the plant and process of the present invention allow regeneration of the spent washing liquid in a possibly already existing stripper, i.e. , making use of a stripper having substantially the same size in an already running plant or process.

[0037] Advantageously, in the plant and process of the present invention the stripper performs a purification of both the process condensate and of the spent liquid. This means that the top waste stream contains undesired and condensable substances that are contained after reforming and WGS, and incondensable byproducts of the CO2 washing step or column.

[0038] Advantageously, the top waste stream can be at least partially recycled as feed to the reforming section or step and / or to the WGS conversion reactor or step, thus reducing or eliminating emissions to the environment and thus any further processing of carbon-loaded streams. Advantageously, the method of revamping of the present invention allows the described process to be easily implemented in existing plants.

[0039] Preferred embodiments

[0040] According to a first embodiment, said H2 product 10 is an ammonia synthesis gas comprising hydrogen and nitrogen (N2) in a H2:N2 molar ratio of approx. 3 and, optionally, inert gases (i.e., argon and methane) in an amount of below 0.5% molar.

[0041] According to a second embodiment, said H2 product 10 is a high-purity hydrogen product, i.e., having a hydrogen content higher than 95% molar, more preferably higher than 99% molar, even more preferably higher than 99.7% molar, still more preferably higher than 99.999% molar.

[0042] Said hydrogen product 10 may be used as a reagent for the synthesis of ammonia and / or methanol, or may be a fuel grade hydrogen product. In the former embodiment, the present plant or process are preferably integrated in an ammonia synthesis and / or a methanol synthesis plant or process.

[0043] According to different embodiments, the hydrogen purification section 9 comprises at least one of the following: a pressure swing absorption (PSA) unit, a cryogenic separation unit, a liquid nitrogen wash (LNW), a membrane separator, and combinations thereof, preferably a PSA unit or a combination of a PSA unit and a cryogenic separation unit.

[0044] According to other embodiments, the CO2 removal unit 8 may comprise at least one of the following: a pressure swing absorption (PSA) unit, a cryogenic separation unit, a membrane separator, and combinations thereof, preferably a PSA unit or a combination of a PSA unit and a cryogenic separation unit.

[0045] Preferably, the hydrocarbon feedstock is natural gas.

[0046] More preferably, the WGS conversion reactor 6 is arranged for converting said raw synthesis gas 4 into a shifted gas 11 . According to a first embodiment, the liquid-gas separator 7 is arranged upstream of said CO2 removal unit 8.

[0047] Preferably, the liquid-gas separator 7 is configured for separating said shifted gas 11 into said process condensate 12 and a gaseous phase 13 provided to the CO2 removal unit 8.

[0048] According to a second embodiment, the CO2 removal unit 8 is arranged upstream of said liquid-gas separator 7.

[0049] Preferably, the CO2 removal unit 8 is arranged for separating said shifted gas 11 into said CO2-enriched stream 14 and a CO2-depleted stream 30 provided to the liquid-gas separator 7.

[0050] According to an embodiment, the plant comprises at least a line 23, 24 for recycling at least a portion or all of said top waste stream 18 as feed to said reforming section 2 and / or to said WGS conversion reactor 6.

[0051] According to another embodiment, the plant comprises at least a compressor 28 of said CO2-enriched stream 14 arranged upstream of said washing column 20, and, optionally a drying section 26 of the purified CO2 stream 21 providing a dried CO2-enriched stream 27.

[0052] Preferably, for embodiments wherein the CO2 removal unit 8 comprises a combination of a PSA unit and a cryogenic separation unit, a part 48 of said dried CO2-enriched stream 27 may be recycled to the CO2 removal unit 8 to be processed - e.g. in a dedicated PSA unit - to obtain a CO2 product 49.

[0053] According to different embodiments, said at least one compressor 28 is a single- stage or a multi-stage compressor.

[0054] Preferably, one or more compressor stage(s) 25, 25’ of such multi-stage compressor 28 are arranged upstream of said washing column 20, and one or more compressor stage(s) 25” of such multi-stage compressor 28 are arranged downstream of said washing column 20 and of said optional drying section 26.

[0055] These stages 25, 25’, 25” may be driven by common motor means 32, said motor means 32 preferably comprising a steam or gas turbine. According to a preferred embodiment, said reforming section 2 comprises an autothermal reforming (ATR) reactor. Preferably, said reforming section 2 comprises a pre-reformer followed by said ATR reactor. More preferably, said pre-reformer and said ATR reactor are without a primary reforming reactor therebetween.

[0056] Preferably, said pre-reformer comprises at least one adiabatic pre-reformer.

[0057] In a preferred embodiment of the invention a steam to carbon (S / C) ratio at the inlet of the pre-reformer is kept to a value not greater than 1.5, preferably comprised from 0.7 to 1.5, more preferably comprised from 0.9 to 1.4 or 1.1 to 1 .3, for example of about 1 .2.

[0058] According to another embodiment, said reforming section 2 comprises - in this sequence - an optional pre-reformer, a primary reforming reactor followed by a secondary reforming reactor.

[0059] In presence of a pre-reformer, a S / C ratio at the inlet of the pre-reformer is preferably kept to a value not lower than 1 .5.

[0060] In absence of a pre-reformer, a S / C ratio at the inlet of the primary reforming reactor is preferably kept to a value not lower than 2.8.

[0061] According to a first embodiment, the liquid-gas separation 7 is performed before said CO2 removal 8.

[0062] Preferably, said liquid-gas separation 7 is configured for separating said shifted gas 11 into said process condensate 12 and a gaseous phase 13 provided to the CO2 removal 8.

[0063] According to a second embodiment, the CO2 removal 8 is performed before said liquid-gas separation 7.

[0064] Preferably, the CO2 removal 8 is arranged for separating said shifted gas 11 into said CO2-enriched stream 14 and a CCh-depleted stream 30 provided to the liquid-gas separation 7. According to another embodiment, the process comprises recycling 23, 24 at least a portion or all of said top waste stream 18 as feed to said reforming 2 of step (I) and / or to said WGS conversion 6 of step (II).

[0065] The process preferably comprises at least a compression step 28 of said CO2- enriched stream 14 to a target pressure before step (IV) and, optionally, a drying step 26 of the purified CO2 stream 21 providing a dried CO2-enriched stream 27. Said target pressure may be higher than 10 bar gauge (barg), preferably comprised from 10 barg to 55 barg, more preferably comprised from 20 barg to 45 barg, even more preferably comprised from 30 barg to 35 barg.

[0066] According to different embodiments, said at least one compression step 28 is a single-stage or multi-stage compression.

[0067] More preferably, one or more compressor stage(s) 25, 25’ of such multi-stage compression 28 are performed before step (IV), and one or more compression stage(s) 25” of such multi-stage compression are performed after said step (IV) and of said optional drying step 26.

[0068] According to a preferred embodiment, said reforming 2 of step (I) comprises an autothermal reforming (ATR) step. Preferably, said reforming 2 comprises a prereforming step followed by said ATR step. More preferably, said pre-reforming step and said ATR step are without a primary reforming step therebetween.

[0069] According to another embodiment, said reforming 2 of step (I) comprises - in this sequence - an optional pre-reforming step, a primary reforming step followed by a secondary reforming step.

[0070] Preferably, a second portion 45 of the bottom stripped liquid 17 may be sent to a polishing unit 42 to be recovered (preferably as demi water).

[0071] The advantages of the invention will be even more evident from the following detailed description made on the basis of the enclosed figures, which are provided as a non-limiting example. Description of the figures

[0072] From Fig. 1 to Fig. 6: different embodiments of the plant or process of the present invention according to possible embodiments;

[0073] Fig. 7: a detailed view of the liquid-gas separator according to a possible embodiment.

[0074] Detailed description of the invention according to a preferred embodiment

[0075] Fig. 1 shows a process or plant for the synthesis of a hydrogen (H2) product 10 according to a first embodiment of the present invention. Even though the below description will relate to the plant, the process comprises corresponding technical features.

[0076] The plant comprises a reforming section 2, a post-treatment section 5, a stripping column 15, a washing column 20, and a line 22.

[0077] The reforming section 2 is fed with a hydrocarbon feedstock 3, and is configured to convert such hydrocarbon feedstock 3 into a raw synthesis gas 4.

[0078] The post-treatment section 5 of the raw synthesis gas 4 comprises - in sequence and in this order - a water gas shift (WGS) conversion reactor 6, a liquid-gas separator 7, a carbon dioxide (CO2) removal unit 8, and a hydrogen purification section 9.

[0079] The WGS conversion reactor 6 is arranged for converting the raw synthesis gas 4 into a shifted gas 11 . The shifted gas 11 feeds the liquid-gas separator 7.

[0080] The liquid-gas separator 7 is configured for separating the shifted gas 1 1 into a process condensate 12 and a gaseous phase 13 provided to the CO2 removal unit 8.

[0081] The CO2 removal unit 8 is arranged for separating the gaseous phase 13 into a CO2-enriched stream 14 and a CO2-depleted stream 30. The CO2-depleted stream 30 is a stream enriched in hydrogen with respect to the gaseous phase 13. The hydrogen purification section 9 is fed with the CCh-depleted stream 30. The output of the hydrogen purification section 9 is the H2 product 10.

[0082] The stripping column 15 is arranged for stripping the process condensate 12 with a stripping medium 16, e.g., steam, to obtain a bottom stripped liquid 17 and a top waste stream 18.

[0083] At least a portion of (e.g., all) the top waste stream 18 that exits the stripping column 15 overhead is recycled through one or more lines 23, 24 as feed to the reforming section 2 and / or to said WGS conversion reactor 6.

[0084] Upstream of the stripping column 15, the process condensate 12 may exchange heat with the bottom stripped liquid 17 in a first indirect heat exchanger 29.

[0085] The process condensate 12 flows into the stripping column 15 through the line 22.

[0086] The bottom stripped liquid 17, after exchanging heat in the first indirect heat exchanger 29, may be split into a first portion 44 and a second portion 45.

[0087] The second portion 45 of the bottom stripped liquid 17 may be sent to a polishing unit 42 to be recovered e.g. as demi water. The first portion 44 is passed through a further indirect heat exchanger 46 (optional), and is then directed to the washing column 20, wherein it is contacted with the CCh-enriched stream 14.

[0088] The CO2-enriched stream 14 is thus freed from any by-product(s) deriving from the upstream reactions. These by-products may comprise ammonia and / or methanol. Ammonia may be formed in the reforming section. Methanol may be a side product formed in the WGS conversion reactor.

[0089] A spent liquid 19 containing said by-product(s) and a purified CO2 stream 21 are drawn from the washing column 20. The purified CO2 stream 21 may be stored or exported from the plant 1 . The spent liquid 19 is mixed with the process condensate 12, flows through the first indirect heat exchanger 29 and - through line 22 - is recycled to the stripping column 15.

[0090] Fig. 2 shows a process or plant for the synthesis of a H2 product 10 according to a second embodiment of the present invention.

[0091] The embodiment of Fig. 2 differs from the embodiment of Fig. 1 in that the liquidgas separator 7 and the CO2 removal unit 8 are arranged in reversed order. Accordingly, the post-treatment section 5 of the raw synthesis gas 4 comprises - in sequence and in this order - the WGS conversion reactor 6, the CO2 removal unit 8, the liquid-gas separator 7, and the hydrogen purification section 9.

[0092] According to such embodiment, the CO2 removal unit 8 is fed with the shifted gas 11 and is arranged for separating the shifted gas 11 into the CO2-enriched stream 14 and the CO2-depleted stream 30. The CO2-enriched stream 14 is fed to the washing column 20 wherein it is contacted with the bottom stripped liquid 17. The CO2-depleted stream 30 provided to the liquid-gas separator 7.

[0093] In the liquid-gas separator 7 the CO2-depleted stream 30 is separated into the process condensate 12 and the gaseous phase 13. The gaseous phase 13 is directed to the H2 purification section 9. The process condensate 12 is fed to the stripping column 15 flowing through the first indirect heat exchanger 29.

[0094] Fig. 3 shows a process or plant for the synthesis of a H2 product 10 according to a third embodiment of the present invention.

[0095] The embodiment of Fig. 3 differs from the embodiment of Fig. 1 in that the CO2- enriched stream 14 is compressed in a compressor 28, in this case having a single-compressor stage 25. A first compressed stream 31 leaves the compressor 28 and is fed to the washing column 20.

[0096] Another difference with respect to Fig. 1 is that the purified CO2 stream 21 may be passed through an optional drying section 26 to obtain a dried CO2-enriched stream 27. Still another difference with respect to Fig. 1 is that, for embodiments wherein the CO2 removal unit 8 comprises a combination of a PSA unit and a cryogenic separation unit, the purified CO2 stream 21 or dried CO2-enriched stream 27 may be split in at least a first part 47 and a second part 48.

[0097] The first part 47 may be stored or exported from the plant 1 .

[0098] The second part 48 may be recycled to the CO2 removal unit 8 to be processed - e.g. in a dedicated cryogenic separation unit - to obtain a CO2 product 49. The CO2 product 49 may be stored or exported from the plant 1 .

[0099] Fig. 4 shows a process or plant for the synthesis of a H2 product 10 according to a fourth embodiment of the present invention.

[0100] The embodiment of Fig. 4 differs from the embodiment of Fig. 2 in that the CO2- enriched stream 14 is compressed in a compressor 28, in this case having a single-compressor stage 25. The first compressed stream 31 leaves the compressor 28 and is fed to the washing column 20.

[0101] Another difference with respect to Fig. 2 is that the purified CO2 stream 21 may be passed through an optional drying section 26 to obtain a dried CO2-enriched stream 27. The dried CO2-enriched stream 27 may be stored or exported from the plant 1 .

[0102] Still another difference with respect to Fig. 2 is that, for embodiments wherein the CO2 removal unit 8 comprises a combination of a PSA unit and a cryogenic separation unit, the purified CO2 stream 21 or dried CO2-enriched stream 27 may be split in at least a first part 47 and a second part 48.

[0103] The first part 47 may be stored or exported from the plant 1 .

[0104] The second part 48 may be recycled to the CO2 removal unit 8 to be processed - e.g. in a dedicated cryogenic separation unit - to obtain a CO2 product 49. The CO2 product 49 may be stored or exported from the plant 1 . Fig. 5 shows a process or plant for the synthesis of a H2 product 10 according to a fifth embodiment of the present invention.

[0105] The embodiment of Fig. 5 differs from the embodiment of Fig. 3 in that the CO2- enriched stream 14 is compressed in a multi-stage compressor 28, in this case having at least two (or only two) compressor stages 25, 25’ arranged upstream of the washing column 20 and one or more compressor stage(s) 25” arranged downstream of the washing column 20 and of said optional drying section 26. These stages 25, 25’, 25” may be driven by common motor means 32.

[0106] The first compressed stream 31 leaves a first compressor stage 25 and enters a suction side of a second compressor stage 25’. A second compressed stream 33 leaves a delivery side of the second compressor stage 25’ and is fed to the washing column 20.

[0107] At least a first part 47 of the purified CO2 stream 21 or the dried CO2-enriched stream 27 enters a suction side of a third compressor stage 25”, and a third compressed stream 34 leaves a delivery side of the third compressor stage 25”.

[0108] The third compressed stream 34 may be stored or exported from the plant 1 .

[0109] Still another difference with respect to Fig. 3 is that, for embodiments wherein the CO2 removal unit 8 comprises a combination of a PSA unit and a cryogenic separation unit, a second part 48 of said purified CO2 stream 21 or dried CO2- enriched stream 27 may be recycled to the CO2 removal unit 8 to be processed - e.g. in a dedicated cryogenic separation unit - to obtain a CO2 product 49. The CO2 product 49 may be fed to the suction side of the third compressor stage 25”.

[0110] Fig. 6 shows a process or plant for the synthesis of a H2 product 10 according to a sixth embodiment of the present invention.

[0111] The embodiment of Fig. 6 differs from the embodiment of Fig. 3 in that the CO2- enriched stream 14 is compressed in a multi-stage compressor 28, in this case having at least two (or only two) compressor stages 25, 25’ arranged upstream of the washing column 20 and one or more compressor stage(s) 25” arranged downstream of the washing column 20 and of said optional drying section 26.

[0112] These stages 25, 25’, 25” may be driven by common motor means 32.

[0113] The first compressed stream 31 leaves a first compressor stage 25 and enters a suction side of a second compressor stage 25’. A second compressed stream 33 leaves a delivery side of the second compressor stage 25’ and is fed to the washing column 20.

[0114] At least a first part 47 of the purified CO2 stream 21 or the dried CCh-enriched stream 27 enters a suction side of a third compressor stage 25”, and a third compressed stream 34 leaves a delivery side of the third compressor stage 25”. The third compressed stream 34 may be stored or exported from the plant 1 .

[0115] Still another difference with respect to Fig. 3 is that, for embodiments wherein the CO2 removal unit 8 comprises a combination of a PSA unit and a cryogenic separation unit, a second part 48 of said purified CO2 stream 21 or dried CO2- enriched stream 27 may be recycled to the CO2 removal unit 8 to be processed - e.g. in a dedicated cryogenic separation unit - to obtain a CO2 product 49. The CO2 product 49 may be fed to the suction side of the third compressor stage 25”.

[0116] Fig. 7 shows a detailed view of a liquid-gas separator, according to a possible embodiment, that can be implemented in any of the previous embodiments.

[0117] The liquid-gas separator 7 according to such embodiment comprises a second indirect heat exchanger 40, a first condensate separator 35, a second condensate separator 38, and a flash drum 41 .

[0118] The shifted gas 11 or the CO2-depleted stream 30 is cooled in the second indirect heat exchanger 40, and a cooled shifted gas 1 T or cooled CO2-depleted stream 30’ drawn from such heat exchanger 40 is fed to the first condensate separator 35 wherein said gas 1 T or stream 30’ is separated into a first bottom liquid 36 and a first head gas 37. The first head gas 37 is fed to the second condensate separator 38 wherein said first head gas 37 is separated into the gaseous phase 13 and a second bottom liquid 39.

[0119] The first bottom liquid 36 and the second bottom liquid 39 are both fed to the flash drum 41 . A second head gas 43 and the process condensate 12 are drawn from the flash drum 41 . The second head gas 43 may be combusted and vented.

[0120] Even if not specified above, a person skilled in the art may envisage, using the expertise typical of this technological field, varying, or replacing some of the above features with other technically equivalent elements. These variations or replacements also fall within the scope defined by the following claims.

[0121] Furthermore, each alternative illustrated in connection with a particular embodiment can be realised independently of the other embodiments here described.

[0122] LIST OF THE REFERNCE SIGNS plant or process reforming section or step hydrocarbon feedstock, preferably natural gas raw synthesis gas post-treatment section or step water gas shift (WGS) conversion reactor or step liquid-gas separator or separation carbon dioxide (CO2) removal unit or step hydrogen purification section or step hydrogen (H2)-containing product shifted gas ’ cooled shifted gas process condensate gaseous phase

[0123] CO2-enriched stream stripping column or step stripping medium, preferably steam bottom stripped liquid top waste stream spent liquid washing column purified CO2 stream recycling line or step of at least part of the spent liquid line for recycling at least a portion of the top waste stream line for recycling at least a portion of the top waste stream compressor or compression stage ’ compressor or compression stage ” compressor or compression stage drying section or step dried CCh-enriched stream compressor or compression step, preferably single-stage or multi-stage compressor or compression indirect heat exchanger

[0124] CO2-depleted stream ’ cooled CO2-depleted stream first compressed stream motor means, preferably a steam or gas turbine second compressed stream third compressed stream first condensate separator first bottom liquid first head gas second condensate separator second bottom liquid second indirect heat exchanger, preferably water-cooled indirect heat exchanger flash drum polishing unit or step second head gas

[0125] (first) portion of the bottom stripped liquid

[0126] (second) portion of the bottom stripped liquid further indirect heat exchanger

[0127] (first) part of the dried CCh-enriched stream or purified CO2 stream

[0128] (second) part of the dried CCh-enriched stream or purified CO2 stream carbon dioxide (CO2) product

Claims

CLAIMS1 . A plant (1 ) for the synthesis of a hydrogen (H2) product (10) comprising:- a reforming section (2) configured to convert a hydrocarbon feedstock (3) into a raw synthesis gas (4);- a post-treatment section (5) of said raw synthesis gas (4) comprising at least a water gas shift (WGS) conversion reactor (6), a liquid-gas separator (7), a carbon dioxide (CO2) removal unit (8), and a hydrogen purification section (9) providing said H2 product (10); wherein said liquid-gas separator (7) is configured for producing a process condensate (12), and wherein said CO2 removal unit (8) is arranged for separating a CCh-enriched stream (14);- a stripping column (15) arranged for stripping said process condensate (12) with a stripping medium (16) to obtain a bottom stripped liquid (17) and a top waste stream (18);- a washing column (20) arranged for washing said CCh-enriched stream (14) with at least a portion (44) said bottom stripped liquid (17) thus obtaining a spent liquid (19) containing one or more by-product(s), such as ammonia and / or methanol, and a purified CO2 stream (21 );- a line (22) for recycling at least part of said spent liquid (19) to the stripping column (15).

2. The plant according to claim 1 , wherein said liquid-gas separator (7) is arranged upstream of said CO2 removal unit (8), said WGS conversion reactor (6) being arranged for converting said raw synthesis gas (4) into a shifted gas (11 ), and wherein said liquid-gas separator (7) is configured for separating said shifted gas (11 ) into said process condensate (12) and a gaseous phase (13) provided to the CO2 removal unit (8).

3. The plant according to claim 1 , wherein said CO2 removal unit (8) is arranged upstream of said liquid-gas separator (7), said WGS conversion reactor (6) being arranged for converting said raw synthesis gas (4) into a shifted gas (11 ), and wherein said CO2 removal unit (8) is arranged forseparating said shifted gas (11 ) into said CC -enriched stream (14) and a CCh-depleted stream (30) provided to the liquid-gas separator (7).

4. The plant according to any of the previous claims, comprising:- at least a line (23, 24) for recycling at least a portion or all of said top waste stream (18) as feed to said reforming section (2) and / or to said WGS conversion reactor (6).

5. The plant according to any of the previous claims, comprising:- at least a compressor (28) of said CCh-enriched stream (14) arranged upstream of said washing column (20);- and optionally a drying section (26) of the purified CO2 stream (21 ) providing a dried CCh-enriched stream (27).

6. The plant according to the previous claim, wherein said at least one compressor (28) is a multi-stage compressor, one or more compressor stage(s) (25, 25’) of such multi-stage compressor (28) being arranged upstream of said washing column (20), and one or more compressor stage(s) (25”) of such multi-stage compressor (28) being arranged downstream of said washing column (20) and of said optional drying section (26).

7. The plant according to any of the previous claims, wherein said reforming section (2) comprises an autothermal reforming (ATR) reactor, preferably a pre-reformer followed by said ATR reactor, more preferably without a primary reforming reactor therebetween.

8. A process (1 ) for the synthesis of a hydrogen (H2) product (10), said process comprising the following steps:(I) reforming (2) of a hydrocarbon feedstock (3) into a raw synthesis gas (4);(II) post-treatment (5) of said raw synthesis gas (4) comprising at least a water gas shift (WGS) conversion (6), a liquid-gas separation (7), a carbon dioxide (CO2) removal (8) and a hydrogen purification (9); wherein said liquid-gas separation (7) produces a process condensate(12), and wherein said CO2 removal (8) is arranged for separating a CO2-enriched stream (14);(III) stripping (15) of said process condensate (12) with a stripping medium (16) to obtain a bottom stripped liquid (17) and a top waste stream (18);(IV) washing (20) of said CO2-enriched stream (14) with at least a portion (44) of said bottom stripped liquid (17) thus obtaining a spent liquid (19) containing one or more by-product(s), such as ammonia and / or methanol, and a purified CO2 stream (21 );(V) recycling (22) at least part of said spent liquid (19) to said stripping (15) of step (III).

9. The process according to claim 8, wherein said liquid-gas separation (7) is performed before said CO2 removal (8), said WGS conversion (6) being arranged for converting said raw synthesis gas (4) into a shifted gas (11 ), and wherein said liquid-gas separation (7) is configured for separating said shifted gas (11 ) into said process condensate (12) and a gaseous phase(13) provided to the CO2 removal (8).

10. The process according to claim 8, wherein said CO2 removal (8) is performed before said liquid-gas separation (7), said WGS conversion (6) being arranged for converting said raw synthesis gas (4) into a shifted gas (11 ), and wherein said CO2 removal (8) is arranged for separating said shifted gas (11 ) into said CO2-enriched stream (14) and a CO2-depleted stream (30) provided to the liquid-gas separation (7).11 . The process according to any of claims 8-10, comprising:- recycling (23, 24) at least a portion or all of said top waste stream (18) as feed to said reforming (2) of step (I) and / or to said WGS conversion (6) of step (II).

12. The process according to any of claims 8-11 , comprising:- at least a compression step (28) of said CCh-enriched stream (14) to a target pressure before step (IV);- and optionally a drying step (26) of the purified CO2 stream (21 ) providing a dried CCh-enriched stream (27); preferably wherein said at least one compression step (28) is a multi-stage compression, one or more compressor stage(s) (25, 25’) of such multistage compression (28) being performed before said step (IV), and one or more compression stage(s) (25”) of such multi-stage compression being performed after said step (IV) and of said optional drying step (26).

13. The process according to any of claims 8-12, wherein said H2 product (10) is:- an ammonia synthesis gas comprising at least hydrogen and nitrogen (N2) in a H2:N2 molar ratio of approx. 3; or- a high-purity hydrogen product, i.e. , having a hydrogen content higher than 95% molar, more preferably higher than 99% molar, even more preferably higher than 99.7% molar, still more preferably higher than 99.999% molar.

14. The process according to any of claims 8-13, wherein said reforming (2) of step (I) comprises an autothermal reforming (ATR) step, preferably a prereforming step followed by said ATR step, more preferably without a primary reforming step therebetween.

15. A method of revamping a plant for the synthesis of a hydrogen (H2) product, said plant to be revamped comprising at least: a reforming section;- a water gas shift (WGS) conversion reactor, a liquid-gas separator, a carbon dioxide (CO2) removal unit, and a hydrogen purification section providing said H2 product; said method of revamping comprising: (A) if not already available, installing a stripping column (15) arranged for stripping a process condensate (12) produced by the liquid-gas separator (7) with a stripping medium (16) to obtain a bottom stripped liquid (17) and a top waste stream (18);(B) installing a washing column (20) arranged for washing a CO2-enriched stream (14) separated by the CO2 removal unit (8) with at least a portion(44) of said bottom stripped liquid (17) thus obtaining a spent liquid (19) containing one or more by-product(s), such as ammonia and / or methanol, and a purified CO2 stream (21 );(C) installing a line (22) for recycling at least part of said spent liquid (19) to the stripping column (15).

Images