阅读说明：本技术 化学合成设备 (Chemical synthesis equipment ) 是由 S·德萨卡尔 T·S·克里斯滕森 M·奥斯特伯格 K·阿斯伯格-彼得森 于 2020-04-07 设计创作，主要内容包括：提供了一种设备,例如烃设备,其由合成气级(用于合成气生成)和合成级(其中合成所述合成气以产生合成气衍生产品如烃产品)组成。该设备有效利用各种流；特别是CO-(2)和H-(2)。该设备不包括外部烃进料。还提供了一种用于产生产品流(例如烃产品流)的方法。(A plant, such as a hydrocarbon plant, is provided that consists of a synthesis gas stage (for synthesis gas generation) and a synthesis stage (in which the synthesis gas is synthesized to produce a synthesis gas derivative)Production products such as hydrocarbon products). The apparatus efficiently utilizes various streams; in particular CO 2 And H 2 . The apparatus does not include an external hydrocarbon feed. A method for producing a product stream (e.g., a hydrocarbon product stream) is also provided.)

1. A device (X), the device comprising:

a. a synthesis gas stage (A) comprising a methanation section (II) and/or a reverse water gas shift (rWGS) section (III) and an autothermal reforming (ATR) section (I), and

b. a synthesis stage (B);

the apparatus comprises:

-a first feed (1) comprising hydrogen to the synthesis gas stage (a);

-a second feed (2) comprising carbon dioxide to the synthesis gas stage (a);

-a third feed (3) comprising oxygen to the ATR section;

wherein the synthesis gas stage (A) is arranged to provide a synthesis gas stream (100) and to feed the synthesis gas stream (100) to a synthesis stage (B); and wherein the apparatus does not include an external hydrocarbon feed.

2. The plant according to claim 1, wherein the syngas stage comprises a methanation section (II) and/or a reverse water gas shift (rWGS) section (III) arranged upstream of the autothermal reforming (ATR) section (I).

3. The plant according to claim 1, wherein the syngas stage comprises a methanation section (II) and/or a reverse water gas shift (rWGS) section (III) arranged in parallel with the autothermal reforming (ATR) section (I).

4. The plant according to any of the preceding claims, wherein the synthesis stage (B) is arranged to convert the synthesis gas stream (100) into at least a product stream (500), and optionally a hydrocarbon-containing off-gas stream (4a,4B,4 c).

5. The plant according to claim 4, wherein at least a portion of the hydrocarbon-containing off-gas stream (4a,4b,4c) or at least a portion of the product stream (500) is fed to the syngas stage (A) as a fourth feed comprising hydrocarbons upstream of the ATR section (I) and between the methanation section (II) and/or reverse water gas shift (rWGS) section (III) and the ATR section (I).

6. Plant according to any one of the preceding claims, wherein the synthesis gas stream (100) is fed directly from the synthesis gas stage (A) to the synthesis stage (B).

7. The plant according to any one of claims 1 to 5, wherein the plant comprises a post-conversion section between the synthesis gas stage (A) and the synthesis stage (B), and comprising CO to the post-conversion section₂Said stream comprising CO₂Is arranged to mix with said synthesis gas stream between the synthesis gas stage (a) and the post-conversion stage.

8. The plant according to any one of the preceding claims, further comprising a fifth feed (5) of steam to the synthesis gas stage (A).

9. Apparatus according to any one of the preceding claims, wherein the synthesis gas stage (A) consists of a methanation section (II) arranged upstream of an autothermal reforming (ATR) section (I).

10. Plant according to any one of the preceding claims, wherein part or all of the first feed (1) is fed to the methanation section (II); and part or all of the second feed (2) is fed to the methanation section (II).

11. Plant according to any one of the preceding claims, wherein the methanation section (II) comprises two or more methanation units, for example three or more methanation units.

12. The plant according to any one of the preceding claims, wherein the synthesis gas stream (100) at the inlet of the synthesis stage (B) has a flow rate of between 1.0 and 4.0; preferably a hydrogen/carbon monoxide ratio in the range of from 1.5 to 3.0, more preferably from 1.5 to 2.1.

13. The apparatus according to any one of the preceding claims, wherein H at the apparatus inlet₂:CO₂The ratio is 1.0 to 9.0, preferably 2.5 to 8.0, more preferably 3.0 to 7.0.

14. Plant according to claim 13, wherein said synthesis stage (B) is an FT synthesis stage and H at the plant inlet₂:CO₂The ratio is in the range of 3.0 to 7.0, or more preferably 3.0 to 6.0, and most preferably 3.0 to 5.0.

15. The plant according to any one of the preceding claims, wherein the synthesis stage (B) is a fischer-tropsch (F-T) stage arranged to convert the synthesis gas stream (100) into a hydrocarbon-containing off-gas stream (4a) in the form of at least a hydrocarbon product stream (500) and a F-T off-gas stream.

16. The plant of any one of claims 1 to 13 wherein the synthesis stage (B) comprises a methanol synthesis stage arranged to provide at least a methanol product stream and a methanol off-gas stream, and wherein at least part of the methanol off-gas stream is fed to synthesis stage (a).

17. The plant defined in any one of the preceding claims further comprises an electrolysis cell arranged to convert water or steam into at least a hydrogen-containing gas stream and an oxygen-containing gas stream and wherein at least a portion of the hydrogen-containing gas stream from the electrolysis cell is supplied to the synthesis gas stage (A) as part or all of the first feed and/or wherein at least a portion of the oxygen-containing gas stream from the electrolysis cell is supplied to the synthesis gas stage (A) as part or all of the third feed.

18. The plant according to any one of the preceding claims, comprising a sixth feed of hydrogen to the synthesis gas stream upstream of the synthesis stage (B).

19. The plant of claim 2, wherein part or all of the first feed is fed to the methanation section and/or reverse water gas shift (rWGS) section; and part or all of the second feed is supplied to the methanation section and/or reverse water gas shift (rWGS) section.

20. The apparatus of any one of claims 5-19, wherein

-said syngas stage (a) comprises an inverse water gas shift (rWGS) section (III) arranged in parallel with said ATR section (I);

-wherein at least a part of the first feed (1) and at least a part of the second feed (2) are arranged to be fed to a rWGS section (III) and the rWGS section (III) is arranged to convert the at least a part of the first feed (1) and at least a part of the second feed (2) into a first synthesis gas stream (41);

-wherein a third feed (3) comprising oxygen is arranged to be fed to the ATR section (I); and wherein the ATR section (I) is arranged to convert the third feed comprising oxygen (3) and the fourth feed comprising hydrocarbons into a second synthesis gas stream (50);

-wherein the first syngas stream (41) from the rWGS section (III) is arranged to be combined with the second syngas stream (50) from the ATR section (I); and the combined syngas stream (100) is arranged to be fed to said synthesis stage (B).

21. The plant according to claim 20, wherein the synthesis gas stream (50) from the ATR section (I) is arranged to provide at least part of the energy required for the endothermic reaction in the rWGS section (III) before being combined with the first synthesis gas stream (40).

22. The apparatus of any one of claims 5-19, wherein

-the synthesis gas stage (a) comprises a methanation section (II) arranged in parallel with the ATR section (I);

-wherein at least a part of the first feed (1) and at least a part of the second feed (2) are arranged to be fed to the methanation section (II) and the methanation section (II) is arranged to convert the at least a part of the first feed (1) and at least a part of the second feed (2) into a first synthesis gas stream (31);

-wherein a third feed (3) comprising oxygen is arranged to be fed to the ATR section (I); and wherein the ATR section (I) is arranged to convert the third feed comprising oxygen (3) and the fourth feed comprising hydrocarbons into a second synthesis gas stream (50);

-wherein the first syngas stream (31) from the methanation section (II) is arranged to be combined with the second syngas stream (50) from the ATR section (I); and the combined syngas stream (100) is arranged to be fed to said synthesis stage (B).

23. A method for producing a product stream, the method comprising the steps of:

-providing a device (X) as defined in any one of the preceding claims;

-supplying a first feed (1) comprising hydrogen to the synthesis gas stage (a);

-supplying a second feed (2) comprising carbon dioxide to the synthesis gas stage (a);

-supplying a third feed (3) comprising oxygen to the ATR section;

-converting said first, second, third and optionally fourth feeds in said synthesis gas stage (a) into a synthesis gas stream (100) and feeding said synthesis gas stream (100) to said synthesis stage (B);

-converting the synthesis gas stream (100) in the synthesis stage (B) into at least a product stream (500) and a hydrocarbon-containing stream (4a,4B,4 c); and

-optionally, feeding at least a part of the hydrocarbon-containing stream (4a,4b,4c) or at least a part of the product stream (500) as a fourth feed comprising hydrocarbons to the syngas stage (a) upstream of the ATR stage (I) and preferably between the methanation stage (II) and/or reverse water gas shift (rWGS) stage (III) and the ATR stage (I).

24. The process according to claim 23, wherein the synthesis stage (B) is a fischer-tropsch (F-T) stage arranged to convert the synthesis gas stream into a hydrocarbon-containing off-gas stream in the form of at least a hydrocarbon product stream and a F-T tail gas stream.

Technical Field

The present invention relates to a plant, such as a hydrocarbon plant, that efficiently utilizes various streams, particularly carbon dioxide. A method for producing a product stream (e.g., a hydrocarbon product stream) is also provided. The apparatus does not include an external hydrocarbon feed. The apparatus and method of the present invention generally make better use of carbon dioxide.

Background

In view of atmospheric CO since the industrial revolution₂With increasing Carbon Capture and Utilization (CCU) becoming increasingly important. In the utilization of CO₂In one mode of (A), CO₂And H₂Can be converted into synthesis gas (a rich in CO and H)₂Gas) that can be further converted into valuable products such as alcohols (including methanol), fuels (such as gasoline, jet fuel, kerosene and/or diesel produced, for example, by a fischer-tropsch (F-T) process), and/or olefins, among others.

The prior art focuses mainly on CO and H₂A separate reverse water gas shift (rWGS) process for conversion to synthesis gas. The syngas can then be converted to valuable products in downstream processes as described above. The reverse water gas shift reaction proceeds according to the following reaction:

the rWGS reaction (1) is an endothermic process that requires a large energy input for the desired conversion. Very high temperatures are required to obtain sufficient conversion of carbon dioxide to carbon monoxide to make the process economically viable. Undesirable by-product formation, such as methane, may also occur. High conversion of carbon dioxideIt is obvious that high H can also be passed₂/CO₂And (4) obtaining the proportion. However, this usually results in synthesis gas having (very) too high a H₂the/CO ratio cannot be used for downstream synthesis.

Techniques that rely on the rWGS reaction have other challenges. In some cases, the internally recycled hydrocarbon stream may be obtained as a co-feed. One example is the availability of hydrocarbons from downstream synthesis stages (e.g., propane and butane rich streams from fischer-tropsch stages; tail gases containing different hydrocarbons from fischer-tropsch stages; naphtha streams from fischer-tropsch stages; propane and butane rich streams from gasoline synthesis stages; hydrocarbon streams from olefin synthesis, etc.). Such hydrocarbons cannot be processed in the rWGS reactor. If the hydrocarbon stream from the downstream synthesis stage is at least partially not used for the additional production of synthesis gas, the entire process may not be feasible from an economic point of view.

In order to solve the problems of the prior art, a new synthesis gas preparation process is proposed herein, which synthesis gas is then synthesized mainly from CO₂、H₂And O₂One or more syngas-derived products of the feed. The proposed layout has at least the following advantages:

1.CO₂、H₂and O₂Can be converted to have the desired H₂Syngas in the CO ratio, without any external hydrocarbon feed to the plant.

2. Any hydrocarbon streams produced by the synthesis stage are used for synthesis gas production.

3. Higher utilization of the carbon dioxide feed is possible compared to the individual rWGS sections. One particular goal is to use more CO₂The feed, rather than the external hydrocarbon feed, acts as a carbon source.

4. If an electrolytic cell is used as part or all of the hydrogen feed source for the process, H is reacted with H in the electrolytic cell₂Some or all of the oxygen produced together may be used as a source of oxygen as required in the proposed process arrangement.

Summary of The Invention

Accordingly, in a first aspect, there is provided a device (plant) comprising:

a. a synthesis gas stage (stage) comprising a methanation section (section) and/or a reverse water gas shift (rWGS) section and an autothermal reforming (ATR) section, and

b. a synthesis stage;

the apparatus further comprises:

-a first feed comprising hydrogen to a synthesis gas stage;

-a second feed comprising carbon dioxide to the synthesis gas stage;

-a third feed comprising oxygen to the ATR section;

wherein the synthesis gas stage is arranged to provide a synthesis gas stream and to supply the synthesis gas stream to the synthesis stage; and wherein the apparatus does not include an external hydrocarbon feed.

Also provided is a method of producing a product stream, particularly a hydrocarbon product stream, using the above apparatus.

Further details of the apparatus and method are set forth in the following detailed description, drawings, and claims.

Figures and description

Fig. 1-4 illustrate schematic layouts of various embodiments of an apparatus.

Detailed Description

Any given percentage of gas content is volume% unless otherwise indicated.

Detailed Description

As described above, a plant, such as a hydrocarbon plant, is provided. The apparatus comprises:

a. a syngas stage comprising a methanation section and/or a reverse water gas shift (rWGS) section and an autothermal reforming (ATR) section, and;

b. and (4) a synthesis stage.

The apparatus includes various feeds. For the avoidance of doubt, the term "feed" when applied to a plant refers to the means by which the gas is supplied to the appropriate stage, reactor or unit; such as piping, tubing, etc. A first feed comprising hydrogen is provided to the syngas stage. Suitably, the first feed consists essentially of hydrogen. The first feed of hydrogen is suitably "hydrogen-rich", meaning that the major portion of the feed is hydrogen; that is, more than 75%, e.g., more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of the feed is hydrogen. One source of the first feed of hydrogen may be one or more electrolytic cell units. In addition to hydrogen, the first feed may also comprise, for example, steam, nitrogen, argon, carbon monoxide, carbon dioxide, and/or hydrocarbons. The first feed suitably comprises only small amounts of hydrocarbons, such as for example less than 5% hydrocarbons or less than 3% hydrocarbons or less than 1% hydrocarbons.

A second feed comprising carbon dioxide is provided to the syngas stage. Suitably, the second feed consists essentially of CO₂And (4) forming. CO 2₂Suitably the second feed of (a) is "CO-enriched₂By "means that the major portion of the feed is CO₂(ii) a That is, more than 75%, e.g., more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of the feed is CO₂. One source of the second feed of carbon dioxide may be one or more waste gas streams from one or more chemical plants. One source of the second feed of carbon dioxide may also be carbon dioxide captured from one or more process streams or the atmosphere. Another source of the second feed may be CO captured or recovered from flue gas, e.g., from fired heaters, steam reformers, and/or power plants₂. The first and second feeds may be mixed prior to addition to the syngas stage. In addition to CO₂In addition, the second feed may also include, for example, steam, oxygen, nitrogen, oxygenates, amines, ammonia, carbon monoxide, and/or hydrocarbons. The second feed suitably comprises only a minor amount of hydrocarbons, for example less than 5% hydrocarbons or less than 3% hydrocarbons or less than 1% hydrocarbons.

H provided at the inlet of the apparatus₂:CO₂The ratio varies between 1.0 and 9.0, preferably between 2.5 and 8, more preferably between 3.0 and 7.0. The actual proportions will depend on the desired end product downstream of the synthesis stage. The ratio is defined as any H in the outer stream₂And CO₂(i.e., excluding any hydrogen and/or carbon dioxide in the recycle stream).

The first and second feeds may be mixed prior to addition to the syngas stage.

Desired H of syngas when the synthesis stage is an FT synthesis stage₂the/CO ratio is generally about 2.0. Using a simple view point, will be per unit of CO₂One unit of hydrogen is required for conversion to CO. O is₂Will also require some hydrogen and will also require hydrogen as an energy source for ancillary uses such as power generation. In summary, this means that for the FT synthesis stage, H at the plant inlet₂:CO₂The ratio (i.e. excluding any hydrogen and/or carbon dioxide in the recycle stream) should be in the range of 3.0 to 7.0, or more preferably 3.0 to 6.0, and most preferably 3.0 to 5.0. Similar considerations can be made if the desired end product is methanol or gasoline (via methanol synthesis and methanol-to-gasoline routes), and in these cases, H at the plant inlet₂:CO₂The ratio should be in the range of 3.0 to 7.0, or more preferably 3.0 to 6.0, and most preferably 3.0 to 5.0.

It should be noted that in some cases, H less than 3.0, e.g., between 2.0-3.0, may be used₂:CO₂And (4) proportion.

A third feed comprising oxygen is provided to the ATR section. Suitably, the third feed consists essentially of oxygen. O is₂Suitably the third feed of (a) is "O-rich₂By "means that the major portion of the feed is O₂(ii) a That is, more than 75%, e.g., more than 90% or more than 95%, e.g., more than 99% of the feed is O₂. The third feed may also contain other components, such as nitrogen, argon, CO₂And/or steam. The third feed typically includes a small amount of steam (e.g., 5-10%). The source of the third feed oxygen may be at least one Air Separation Unit (ASU) and/or at least one membrane unit. The source of oxygen may also be at least one cell unit. Part or all of the first feed and part or all of the third feed may come from at least one electrolytic cell. An electrolytic cell refers to a unit that converts steam or water into hydrogen and oxygen by using electric energy. Steam may be added to the third feed comprising oxygen upstream of the ATR section.

A hydrocarbon-containing off-gas stream (from the synthesis stage) may be supplied to the synthesis gas stage as a fourth feed comprising hydrocarbons. Fourth feedThe source of (b) may be part or all of the hydrocarbon-containing stream produced in the synthesis stage. The fourth feed may additionally comprise other components, for example CO₂And/or CO and/or H₂And/or steam and/or other components such as nitrogen and/or argon. The stream may comprise, for example, methane, ethane, propane, and/or butane. LPG may be produced in, for example, a gasoline synthesis unit or a fischer-tropsch synthesis unit. Another example is a stream comprising naphtha, which is produced at the synthesis stage for the production of liquid fuels by a fischer-tropsch synthesis process. Suitably, the hydrocarbon-containing off-gas stream comprises more than 5%, such as more than 15%, for example more than 30%, preferably more than 40% hydrocarbons. The concentration of hydrocarbons in the stream is determined prior to the addition of any steam (i.e., determined as a "dry concentration"). Many recycle streams may be added to different points of the syngas stage, either mixed or added separately, in other words, the fourth feed may be several separate or mixed streams.

Another possibility is the so-called tail gas from a fischer-tropsch unit. Such tail gases usually contain CO₂、CO、H₂Methane and olefins.

The following table provides some examples (non-exhaustive) of possible sources for the fourth feed and corresponding synthesis stages.

In some cases, the stream comprising hydrocarbons may be pre-reformed before being provided as a fourth feed to the syngas stage. For example, when the fourth feed is, for example, an LPG and/or naphtha product stream or a natural gas feed, the plant may further comprise a pre-reforming section arranged in the fourth feed upstream of the synthesis gas stage. The steam feed is arranged to be mixed with the LPG and/or naphtha product stream before being fed to the pre-reforming section.

In the pre-reforming step, the following (endothermic) steam reforming reaction and reaction (3) (exothermic) take place to convert higher hydrocarbons. Additional water gas shift and methanation occur via reactions (1) and (3):

(wherein n is more than or equal to 2, and m is more than or equal to 4) (2)

The prereformer outlet stream will comprise CO₂、CH₄、H₂O and H₂And usually minor amounts of CO and possibly other components. The pre-reforming step is typically carried out at 350-600 ℃ or more preferably between 400 and 550 ℃. Steam is added to the hydrocarbon-containing stream upstream of the pre-reforming step. The pre-reforming step may be carried out adiabatically or in a heated reactor packed with a catalyst including, but not limited to, a Ni-based catalyst. Heating may be achieved by a hot gas (e.g., ATR effluent gas) or using, for example, a fired heater in the heating section. Hydrogen or other combustible components may be used to obtain the necessary heat input.

The hydrocarbon-containing offgas stream may also comprise olefins. In this case, the olefins may be hydrogenated to the corresponding paraffins prior to addition to the pre-reformer or syngas stage.

In some cases, the hydrocarbon-containing waste gas stream contains small amounts of poisons, such as sulfur. In this case, the hydrocarbon-containing waste gas stream may be subjected to one or more purification steps, such as desulfurization.

In one aspect, the apparatus further comprises a steam feed to the syngas stage.

Syngas stage

The synthesis gas stage is arranged to provide a synthesis gas stream (from at least the first, second, third feeds) and to supply the synthesis gas stream to the synthesis stage. For the avoidance of doubt, the terms "synthesis gas" and "synthesis gas" are synonymous. Furthermore, the term "providing a synthesis gas stream" in this context must be understood as "generating a synthesis gas stream".

The syngas stage comprises a methanation section and/or a reverse water gas shift (rWGS) section and an autothermal reforming (ATR) section.

In one embodiment, the methanation section and/or reverse water gas shift (rWGS) section is arranged upstream of the autothermal reforming (ATR) section. In another embodiment, a methanation section and/or an inverse water gas shift (rWGS) section is arranged in parallel with the ATR section.

The syngas stage may include additional sections as desired. The respective segments will be described below.

ATR section

The syngas stage comprises an autothermal reforming (ATR) section. The ATR section may comprise one or more autothermal reactors (ATRs). The key part of the ATR stage is the ATR reactor. All feeds were preheated as required. ATR reactors typically comprise a burner, a combustion chamber and a catalyst bed contained within a refractory-lined pressure shell. In an ATR reactor, a hydrocarbon containing feed stream is steam reformed in a fixed bed of steam reforming catalyst after partial combustion with a sub-stoichiometric amount of oxygen. Due to the high temperature, a certain degree of steam reforming also takes place in the combustion chamber. The steam reforming reaction is accompanied by a water gas shift reaction. Typically, for steam reforming and water gas shift reactions, the gases are at or near equilibrium at the reactor outlet. More details and a complete description of ATR can be found in the art, such as "students in Surface Science and Catalysis, Vol.152," Synthesis gas production for FT Synthesis "; chapter 4, page 258-.

Typically, the effluent gas from the ATR reactor has a temperature of 900-. The effluent gas typically contains H₂、CO、CO₂And steam. Other components such as methane, nitrogen and argon may also often be present in small amounts. The operating pressure of the ATR reactor is from 5 to 100 bar, or more preferably from 15 to 60 bar.

The synthesis gas stream from the ATR is cooled in a cooling train (train) which typically comprises one or more Waste Heat Boilers (WHB) and one or more additional heat exchangers. The cooling medium in the WHB is (boiler feed) water that evaporates to steam. The synthesis gas stream is further cooled below the dew point, for example by preheating the facility and/or partially preheating one or more feed streams and cooling in an air cooler and/or water cooler. Condensed H₂O is in separationIs discharged as process condensate in the vessel to provide a product having a low H₂A synthesis gas stream with O content, which is sent to the synthesis stage.

The "ATR section" may be a partial oxidation "POX" section. The POX section is similar to the ATR section except for the fact that the ATR reactor is replaced by a POX reactor. POX reactors typically include a combustor and a combustion chamber contained in a refractory-lined pressure shell. The ATR stage may also be a catalytic partial oxidation (cPOX) stage.

Methanation section

In one aspect, the syngas stage comprises or consists of a methanation section, preferably arranged upstream of the ATR section. The methanation section is in fluid communication with the ATR section. Part or all of the first feed may be fed to the methanation section; part or all of the second feed may be fed to the methanation section.

The heat generated during methanation completely eliminates or significantly reduces the need for external preheating of the feed to the autothermal reforming stage. Such external preheating can be carried out, for example, in a fired heater. The heat required in such fired heaters is generated by, for example, the combustion of hydrogen and/or hydrocarbons. In the former case, this would consume part of the feed, and in the second case, this would lead to CO₂And (5) discharging. In addition, the fired heater is an expensive piece of equipment that may also occupy a significant footprint. Finally, the methanation section preceding the ATR section improves the overall plant efficiency, for example compared to a separate ATR section.

As mentioned above, from CO₂And hydrogen to produce synthesis gas is based on selective RWGS. The combination of methanation and ATR has several advantages over this approach. This includes the possibility of utilizing an internal recirculation flow. Furthermore, the outlet temperature of the ATR reactor in the ATR section is typically in the range of 900-. In most cases this is higher than the temperature possible with a separate RWGS unit. This increases the production of carbon monoxide, since thermodynamically higher temperatures favor this process. It should also be noted that even if methane is formed in the methanation section, the methane content in the final synthesis gas sent to the synthesis stage is low due to the elevated ATR reaction in the ATR sectionThe mouth temperature. Advantageously, the outlet temperature of the ATR is 1000-.

For most applications, it is an advantage that the methane content in the synthesis gas sent to the synthesis stage is low. For most types of synthesis stages, methane is inert, or even a synthesis stage by-product. Thus, in a preferred embodiment, the content of methane in the synthesis gas sent to the synthesis stage is less than 5%, such as less than 3% or even less than 2%.

The insertion of a methanation section upstream of the ATR section seems to be a departure from the conventional wisdom. Methane is formed in the methanation section and then a major part of the formed methane is converted in the ATR section. However, the inventors have found that the heat of methanation can be used to preheat the feed to the ATR section. This avoids or reduces the need for a dedicated feed preheater. In the case where the preheater is a fired heater using a hydrocarbon fuel, reducing the preheating load will also reduce the combustion required to provide the required energy, thereby reducing the CO₂And (4) discharging. The methanation section may comprise one or more methanation units arranged in series, for example two or more methanation units, three or more methanation units or four or more methanation units. In such methanation units, CO₂And H₂Mainly through exothermic methanation reactions to methane and steam. Each methanation unit may be adiabatic or cooled by, for example, boiling water or by heating, for example, a feed gas. Depending on the degree of methanation and the degree of cooling, the temperature of the effluent from each methanation unit may be 250-. Parallel methanation units are also possible.

In some cases, it may be desirable to avoid excessive temperatures in the methanation unit, for example to limit the extent to which the catalyst deactivates due to sintering. This is especially the case if the methanation unit or the methanation reactor is adiabatic. The highest temperature in an adiabatic methanation unit is usually at the outlet. Thus, it may be desirable to control the outlet temperature of one or more methanation units to a temperature in the range of, for example, 600 ℃ and 750 ℃, for example, about 650 ℃, 675 ℃, 700 ℃ or 725 ℃. If more than one methanation unit is present, this may be achieved by controlling the feed stream to each methanation unit in the methanation section. By controlling the molar ratio between the first feed portion and the second feed portion and between the first feed portion and the fifth feed portion (if present) added to the methanation unit, the outlet temperature of the adiabatic methanation unit may be controlled. Obviously, the inlet temperature of the feed stream may also be used for this purpose.

Control of the ratio of the various feed streams to the methanation unit and the ratio of the various feed streams to the methanation section and directly to the methanation section can also be used to affect the syngas composition.

Portions of the first feed comprising hydrogen may be fed separately to different methanation units in the methanation section; or the first feed comprising hydrogen may all be fed together to the methanation unit located most upstream in the methanation section. Similarly, a plurality of portions of the second feed comprising carbon dioxide may be fed separately to different methanation units in a methanation section; or the second feed comprising carbon dioxide may all be fed together to the methanation unit located most upstream in the methanation section.

In a particular embodiment, all of the first feed comprising hydrogen is fed to the first of the methanation units together with part of the second feed comprising carbon dioxide. The remaining part of the carbon dioxide is distributed between the remaining methanation units and the outlet temperature of the final methanation unit is 650-.

Additional H may be added₂Feed and/or CO₂The feed is added to different parts of the methanation section. For example, part of the hydrogen or CO may be added₂The feed is supplied to a second (or even a third … …) methanation unit. Furthermore, part of the effluent from one methanation unit may be cooled and recycled to the inlet of the methanation unit and/or to the inlet of any additional methanation unit located upstream of the one methanation unit. Optionally, the effluent from the methanation section may be cooled below its dew point and may be recycled to the inlet of the methanation unit or any upstream methanation unitA portion of the water was previously removed from the effluent.

It is also possible to recover the product containing H downstream from the ATR₂And/or CO₂And recycled to the methanation section.

It is also possible to carry out the addition of steam to the methanation section and/or between the methanation section and the ATR section.

In this regard, the exothermic nature of the methanation reaction may be used to preheat the ATR feed. Some heating of the ATR section by external means may be required or desired, for example for control purposes. Thus, the heat of reaction of the methanation reaction may only lead to an increase in the temperature of the portion upstream of the ATR section.

The methanation reaction can be represented by the following formula:

in many cases, the gas composition at the outlet of each methanation unit will be at or near chemical equilibrium with respect to the water gas shift/reverse water gas shift and methanation reactions at the outlet temperature and pressure of the methanation unit.

The methanation reaction (3) is strongly exothermic. In some cases, it may be desirable to adjust the temperature at the outlet of the methanation unit or from the methanation section to a given value, which may be in the range of 550-. If a fourth feed comprising partly or totally hydrocarbons is added to the methanation unit, this may lower the outlet temperature due to the fact that steam reforming (reverse reaction of reaction (3) and/or reaction (2)) will take place.

If the effluent from the pre-reforming step is added to a methanation unit, the outlet temperature from such a methanation unit will typically be lower than if no such stream is added. The methane in the effluent of the prereforming step will react according to the endothermic steam reforming reaction:

the presence of methane in the feed will limit the extent of the methanation reaction due to chemical equilibrium.

The output of the methanation section is a stream comprising CO₂、H₂、CO、H₂O and CH₄The flow of (2).

The off-gas from the FT synthesis stage is typically not added to the methanation unit but is fed directly to the ATR stage. If excess tail gas from the FT synthesis stage is available, it may be hydrogenated and fed to the methanation section.

In one embodiment, the inlet temperature of at least one methanation unit is 300-.

Control of the ratio of the individual feed streams to the methanation unit and the ratio of the individual feed streams to the methanation section and directly to the methanation section may also be used to influence the syngas composition.

The degree of methanation (and hence the composition of the gas to the ATR stage) depends on a number of factors, including the proportion of the feed stream to the methanation stage and the inlet and outlet temperatures to and from each methanation unit and the degree of water removal (if any) from the methanation stage. The synthesis gas from the ATR depends on the amount of oxygen added for a given gas composition and gas temperature to the ATR stage. Increasing the amount of oxygen increases the ATR reactor outlet temperature, thereby decreasing H₂The ratio of/CO.

In another embodiment (as shown in fig. 2 c), the syngas stage (a) comprises a methanation section (II) arranged in parallel with the ATR section (I). At least a portion of the first feed and at least a portion of the second feed are arranged to be fed to a methanation section (II) and the methanation section (II) is arranged to convert the at least a portion of the first feed and at least a portion of the second feed into a first synthesis gas stream. Arranging a third feed of oxygen to be fed to the ATR section (I); and wherein the ATR section (I) is arranged to convert part or all of the internally recycled hydrocarbon stream and the third feed comprising oxygen together with the remaining portions of the first and second streams into a second synthesis gas stream. The first syngas stream from the methanation section (II) is arranged to be combined with the second syngas stream from the ATR section (I); and the combined syngas stream is arranged to be fed to the synthesis stage (B).

This embodiment reduces the amount of oxygen required compared to a series of methanation and ATR stages.

Reverse water gas shift (rWGS) section

In another aspect, the syngas stage comprises or consists of a reverse water gas shift (rWGS) section, preferably arranged upstream of the ATR section. A reverse water gas shift (rWGS) section is in fluid communication with the ATR section. Feeding part or all of the first feed to the rWGS section; and part or all of the second feed is fed to the rWGS section.

As mentioned above, from CO₂And hydrogen to produce synthesis gas is based on selective RWGS. The combination of RWGS and ATR has several advantages over this approach. This includes the possibility of utilizing an internal recirculation flow. Such a stream can be added to the ATR section and used for additional syngas production than would be possible with a separate and selective RWGS. Furthermore, the outlet temperature of the ATR reactor in the ATR section is typically in the range of 900-. In most cases this is higher than the temperature that a separate RWGS unit can reach. This increases the production of carbon monoxide, since thermodynamically higher temperatures favor this process.

In one aspect, the rWGS section comprises one or more rWGS units arranged in series, for example two or more rWGS units, for example three or more rWGS units. In this rWGS unit, CO₂And H₂Conversion to CO and H by reaction (1) above₂. Parallel reverse water gas shift units are also contemplated.

Multiple portions of a first feed comprising hydrogen may be fed to different rWGS units in the rWGS section, respectively; or the first feed comprising hydrogen is all fed together to the inverse WGS unit located most upstream in the rWGS section. Similarly, multiple portions of the second feed comprising carbon dioxide may be fed to different rWGS units in the rWGS section, respectively; or the second feed comprising carbon dioxide may all be fed together to the rWGS unit located furthest upstream in the rWGS section.

Each rWGS unit may be an adiabatic or heated reactor. Heating may be achieved by hot effluent from the ATR or using the heat of combustion of, for example, a hydrocarbon-containing stream and/or a hydrogen-containing stream. The effluent from the rWGS stage is CO-containing₂、H₂、CO、H₂A stream of O. The rWGS effluent temperature from each rWGS unit may be 400-900 deg.C, preferably 500-900 deg.C, more preferably 500-750 deg.C, depending on the extent of rWGS and the extent of heating.

The effluent from the rWGS section is fed to the ATR section. In a particular embodiment, a methanation section may be placed between the rWGS section and the ATR section. In this case, the effluent from the rWGS section is fed to the methanation section and the effluent from the methanation section is fed to the ATR. Reverse water gas shift (rWGS) section-alternative arrangement

In another aspect, the syngas stage comprises an inverse water gas shift (rWGS) section arranged in parallel with said ATR section. A reverse water gas shift (rWGS) section is in fluid communication with the ATR section. Feeding part or all of the first feed to the rWGS section; feeding part or all of the second feed to the rWGS section; wherein the rWGS section is arranged to convert at least a portion of the first feed and at least a portion of the second feed to comprise H₂、CO、CO₂And H₂A syngas stream of O.

Arranging a third feed comprising oxygen together with an optional portion of the first feed comprising hydrogen and/or an optional portion of the second feed comprising carbon dioxide to feed the ATR section; wherein the ATR section is arranged to convert the feed stream to comprise H₂、CO、CO₂、CH₄And H₂O and another syngas stream. A third feed comprising oxygen and a fourth feed of hydrocarbons are also added to the ATR section.

In this respect, the syngas streams from the rWGS section and the ATR section are arranged to be combined to obtain a final syngas stream; wherein the final syngas stream is fed to a synthesis stage.

As mentioned above, from CO₂And hydrogen to produce synthesis gas is based on selective RWGS. In contrast to this solution, parallel connectionThe combination of RWGS and ATR of (a) has several advantages. This includes the possibility of utilizing an internal recirculation flow. CO in rWGS section₂The conversion of a part has the advantage that the overall oxygen consumption can be reduced.

As mentioned above, the rWGS section may comprise one or more rWGS units arranged in series, for example two or more rWGS units, for example three or more rWGS units. In such rWGS units, CO₂And H₂Conversion to CO and H by reaction (1) above₂. Parallel reverse water gas shift units are also conceivable.

Multiple portions of a first feed comprising hydrogen may be fed to different rWGS units in the rWGS section, respectively; or the first feed comprising hydrogen is all fed together to the inverse WGS unit located most upstream in the rWGS section. Similarly, multiple portions of the second feed comprising carbon dioxide may be fed to different rWGS units in the rWGS section, respectively; or the second feed comprising carbon dioxide may all be fed together to the rWGS unit located furthest upstream in the rWGS section.

Each rWGS unit may be an adiabatic or heated reactor. Heating may be achieved by hot effluent from the ATR or using the heat of combustion of, for example, a hydrocarbon-containing stream and/or a hydrogen-containing stream. The effluent from the rWGS stage is CO-containing₂、H₂、CO、H₂A stream of O. The rWGS effluent temperature from each rWGS unit may be 400-900 deg.C, preferably 500-900 deg.C, more preferably 500-750 deg.C, depending on the extent of rWGS and the extent of heating.

CO after ATR₂Conversion unit

In another aspect, the apparatus comprises a post-reforming (post-ATR reforming, PAC) unit or reactor located downstream of the ATR stage.

The PAC unit may be an adiabatic or heated reactor using, for example, Ni-based catalysts and/or catalysts containing noble metals such as Ru, Rh, Pd and/or Ir as active materials. In such PAC units, a stream comprising carbon dioxide, for example part of the second feed, and part or all of the syngas from the ATR section, is mixed and directed to the PAC unit. In the PAC unit, by the two reactions (3) and(1) the combined stream is converted to synthesis gas having a relatively high carbon monoxide content. Reactions (3) and (1) are typically at or near chemical equilibrium at the exit of the PAC unit. The effluent from the PAC stage is comprising CO₂、H₂、CO、H₂O and CH₄The flow of (2). The PAC effluent temperature for each PAC unit may be 700-1000 deg.C, preferably 800-950 deg.C, more preferably 850-920 deg.C. The PAC unit has the advantage of being able to produce effluent streams having a lower H than the effluent stream from the ATR section₂Syngas in a/CO ratio. Furthermore, the fact that a stream comprising carbon dioxide, e.g. a portion of the second feed, is directed to the PAC unit (e.g. adiabatic PAC unit) instead of the ATR section reduces the size of the ATR section. In some cases, this may reduce overall cost.

The effluent stream from the PAC unit is cooled as described above to provide a synthesis gas stream for the synthesis stage.

The CO is₂A Conversion (PAC) unit may be included in any of the aspects described above.

Synthesis stage

The synthesis stage is typically arranged to convert the synthesis gas stream into at least a product stream. A hydrocarbon-containing waste gas stream is typically produced in the synthesis stage. Suitably, at least a portion of the hydrocarbon-containing offgas stream is fed as a fourth feed to a synthesis gas stage upstream of the ATR section, preferably between the methanation and/or reverse water gas shift (rWGS) section and the ATR section.

As noted above, the plant does not include an external hydrocarbon feed, such as a natural gas feed. Thus, the only carbon sources fed to the synthesis stage are from the second feed of carbon dioxide and the recycle stream from the synthesis stage.

The synthesis gas stream at the inlet of the synthesis stage suitably has a pressure in the range 1.00 to 4.00; preferably 1.50 to 3.00, more preferably 1.50 to 2.10, of H₂The proportion of CO. If the synthesis stage is FT stage, then H₂The CO ratio is preferably in the range of 1.50-2.10.

In another embodiment, the synthesis gas stream at the inlet of the synthesis stage suitably has a pressure in the range of from 1.50 to 2.50; preferably 1.80 to 2.30, more preferably 1.90 to 2.20 (H)₂-CO₂)/(CO+CO₂) And (4) proportion.

Some potential examples of synthesis stages are provided below.

Fischer-tropsch synthesis stage

In one aspect, the synthesis stage is a Fischer-Tropsch (F-T) stage. The fischer-tropsch stage comprises a fischer-tropsch (F-T) synthesis section, wherein synthesis gas from the synthesis gas stage is first converted into a hydrocarbon-containing off-gas stream in the form of a crude product comprising at least hydrocarbons and a F-T tail gas stream, followed by a hydrotreating and hydrocracking section, wherein the crude product is converted into at least one or more hydrocarbon product streams. The ratio between long-chain hydrocarbons and olefins in the crude product from the FT synthesis section depends on the type of catalyst used in the process, the reaction temperature, etc.

A hydrocarbon-containing waste gas stream in the form of a fischer-tropsch tail gas stream is produced as a by-product. The F-T tail gas stream typically comprises carbon monoxide (10-40 vol.%), hydrogen (10-40 vol.%), carbon dioxide (10-50 vol.%), and methane (10-40 vol.%). Other components such as argon, nitrogen, olefins and paraffins having two or more carbon atoms may also be present in lesser amounts.

At least a portion of the F-T tail gas stream can be supplied to a syngas stage as the fourth feed comprising hydrocarbons. Suitably, to avoid excessive accumulation of inert components that may be present in the ft tail gas, only a portion of the ft tail gas stream is fed to the synthesis gas stage as a fourth feed; and another portion of the fischer-tropsch tail gas may be purged and/or used as fuel and/or converted to power. In one embodiment, the power, if present, may be used as (part of) the source of the electrolysis unit. Alternatively, the power may be output. Note that the ft-tail gas will typically be fed between the methanation section and the ATR section.

In one embodiment, the primary products from the fischer-tropsch synthesis stage are typically jet fuel and/or kerosene (e.g., comprising primarily C)₁₂–C₁₅) And/or diesel (e.g., comprising primarily C)₁₅–C₂₀). Further, naphtha (e.g., mainly containing C)₅–C₁₂) And LPG (e.g. consisting essentially of C)₃–C₄) The streams are also produced in the F-T synthesis stage. Part or all of such LPG and/or naphtha streams from the F-T synthesis stage may also be used as the feed streamThe fourth feed comprising a hydrocarbon. Part or all of such LPG and/or naphtha streams may be added to the methanation section and/or directly to the ATR section. In another embodiment, some or all of such LPG and/or naphtha may be subjected to a pre-reforming section prior to addition to the methanation section and/or ATR section.

Thus, in a particular embodiment, the synthesis stage is a fischer-tropsch (F-T) stage arranged to convert said synthesis gas stream into at least one hydrocarbon product stream, i.e. a diesel stream; and/or LPG and/or a naphtha product stream and/or a kerosene or jet fuel product stream, and wherein at least a portion of the diesel stream; and LPG and/or naphtha product stream and/or kerosene or jet fuel product stream is fed to the synthesis gas stage. In one aspect, at least a portion of the FT tail gas, at least a portion of the LPG and at least a portion of the naphtha product stream are fed to a synthesis gas stage. In another aspect, at least a portion of the FT tail gas and at least a portion of the LPG are supplied to a syngas stage. The LPG and/or naphtha streams may be treated by pre-reforming before being fed to the syngas stage.

Note that the term "FT stage" herein may include further process steps, such as hydrotreating of the crude effluent from the FT reactor.

Methanol synthesis stage

In another embodiment, the synthesis stage is a methanol (MeOH) synthesis stage. The stage comprises a MeOH synthesis section, wherein synthesis gas from the synthesis gas stage is first converted into a crude MeOH stream, followed by a purification section, wherein the crude MeOH stream is purified to obtain a MeOH product stream. The MeOH synthesis stage produces a purge stream, which typically contains hydrogen, carbon dioxide, carbon monoxide, and methane. Additional components such as argon, nitrogen or oxygenates having two or more carbon atoms may also be present in lesser amounts.

At least a portion of the MeOH purge stream may be supplied to the syngas stage as a fourth feed comprising hydrocarbons. The MeOH purge stream may be purified prior to being fed to the syngas stage. Suitably, to avoid excessive build-up of inert components that may be present in the MeOH purge gas, only a portion of the MeOH purge gas stream may be fed to the syngas stage; and another portion of the MeOH purge gas may be purged and/or used as fuel.

In particular, when the synthesis stage is a methanol synthesis stage, the synthesis gas stream at the outlet of said synthesis stage has a pressure as defined herein between 1.80 and 2.30; modulus in the range of 1.90-2.20 is preferred. The term "modulus" is defined as:

methanol To Gasoline (MTG) synthesis grade

In another embodiment, the synthesis stage is a methanol-to-gasoline (MTG) synthesis stage comprising a MeOH synthesis section, wherein synthesis gas from the synthesis gas stage is first converted into a raw MeOH stream, followed by a gasoline synthesis section, wherein the raw MeOH stream is converted into a gasoline product stream.

The MTG synthesis stage also produces a purge gas stream. This purge stream may be used similarly as explained in the previous section "methanol synthesis stage".

MTG Synthesis grade produces LPG (e.g., comprising primarily C)₃–C₄) And (4) streaming. Part or all of such LPG stream from the MTG synthesis stage may also be fed to the syngas stage as a fourth feed comprising hydrocarbons. Part or the whole LPG stream may be added to the methanation section and/or directly to the ATR section. In another embodiment, part or all of the LPG stream may be pre-reformed before being added to the methanation section and/or ATR section.

Higher Alcohol (HA) synthesis

In another embodiment, the synthesis stage is a Higher Alcohol (HA) synthesis stage comprising an HA synthesis section, wherein the synthesis gas from the synthesis gas stage is first converted into a crude alcohol stream, followed by a purification section, wherein the crude alcohol stream is purified to obtain an HA product stream.

The HA synthesis stage may produce a tail gas stream, which typically contains hydrogen, carbon dioxide, carbon monoxide. Additional components such as argon, nitrogen, methane or oxygenates having two or more carbon atoms may also be present in lesser amounts.

The HA synthesis stage may also produce a methane-rich stream, which typically comprises methane, hydrogen and carbon monoxide. Additional components such as argon, nitrogen, carbon dioxide or oxygenates having two or more carbon atoms may also be present in lesser amounts.

At least a portion of the tail gas and/or the methane-rich stream may be fed to a syngas stage. Suitably, in order to avoid an excessive accumulation of inert components that may be present in the tail gas and/or the methane-rich stream, only a portion of the tail gas and/or the methane-rich stream may be supplied to the synthesis gas stage as the fourth feed; and another portion may be purged and/or used as fuel.

Synthesis of olefins from synthesis gas (STO)

In another embodiment, the synthesis stage is a Syngas To Olefins (STO) synthesis stage comprising an STO synthesis section wherein the syngas from the syngas stage is first converted into a crude olefin-rich stream followed by a purification section wherein the crude olefin-rich stream is purified to obtain an olefin product stream.

The STO synthesis stage can produce a tail gas stream, which typically contains hydrogen, carbon dioxide, carbon monoxide. Additional components such as argon, nitrogen or hydrocarbons having two or more carbon atoms may also be present in lesser amounts.

The STO synthesis stage can also produce a hydrocarbon-rich stream, which typically comprises methane and higher hydrocarbons having two or more carbon atoms. The higher hydrocarbons may be both olefins and paraffins. Additional components such as hydrogen, carbon dioxide, carbon monoxide, argon, nitrogen may also be present in minor amounts.

At least a portion of the tail gas and/or the hydrocarbon-rich stream may be fed to a syngas stage. Suitably, in order to avoid an excessive accumulation of inert components that may be present in the off-gas and/or the hydrocarbon-rich stream, only a portion of the off-gas and/or the hydrocarbon-rich stream may be supplied to the synthesis gas stage as the fourth feed; and another portion may be purged and/or used as fuel.

Synthesis of ethylene oxide from synthesis gas (STEtO)

In another embodiment, the synthesis stage is a syngas to ethylene oxide (STEtO) synthesis stage. The STEtO stage comprises a synthesis gas to olefins (STO) synthesis section in which synthesis gas is first converted to olefin products (primarily ethylene) and then an ethylene oxide synthesis section.

The STO synthesis stage can produce a tail gas stream, which typically contains hydrogen, carbon dioxide, carbon monoxide. Additional components such as argon, nitrogen or hydrocarbons having two or more carbon atoms may also be present in lesser amounts.

The STO synthesis stage can also produce a hydrocarbon-rich stream, which typically comprises methane and higher hydrocarbons having two or more carbon atoms. The higher hydrocarbons may be both olefins and paraffins. Additional components such as hydrogen, carbon dioxide, carbon monoxide, argon, nitrogen may also be present in minor amounts.

At least a portion of the tail gas and/or the hydrocarbon-rich stream may be fed to a syngas stage. Suitably, in order to avoid an excessive accumulation of inert components that may be present in the off-gas and/or the hydrocarbon-rich stream, only a portion of the off-gas and/or the hydrocarbon-rich stream may be supplied to the synthesis gas stage; and another portion may be purged and/or used as fuel.

The ethylene oxide synthesis stage may use at least a portion of the fourth feed (O)₂). During the synthesis of ethylene oxide, a large amount of CO is produced₂As a by-product. CO 2₂The by-products can be recycled and use at least a portion of the first feed to the syngas stage.

Combined production of gasoline and diesel

In another embodiment, the synthesis stage may be a combination of a fischer-tropsch stage and a methanol-to-gasoline (MTG) synthesis stage in parallel with a common syngas feed from the synthesis stage. The F-T section produces middle distillate products (diesel/jet/kerosene etc.) and MTG produces gasoline with the desired octane number. In this embodiment, the syngas stage provides a suitable quality of syngas to the F-T and MTG sections that are operated in parallel with each other. At least a portion of the recycle gas from the F-T and/or at least a portion of the LPG stream from the MTG stage and/or at least a portion of the purge stream from the MeOH synthesis stage may be used as a fourth feed to the syngas stage.

Electrolytic cell

The plant may further comprise an electrolysis cell arranged to convert water or steam into at least a hydrogen containing gas stream and an oxygen containing gas stream, wherein at least a portion of said hydrogen containing gas stream from the electrolysis cell is fed to the synthesis gas stage as said first feed and/or wherein at least a portion of said oxygen containing gas stream from the electrolysis cell is fed to the synthesis gas stage as said third feed. The electrolytic cell may comprise one or more electrolysis cells, e.g. based on solid oxide electrolysis.

Thus, in a preferred embodiment, the apparatus further comprises an electrolytic cell located upstream of the synthesis gas stage. The electrolytic cell is arranged to convert water or steam into at least a hydrogen containing gas stream and an oxygen containing gas stream.

At least a portion of the hydrogen-containing gas stream from the electrolysis cell is fed to the synthesis gas stage as said first feed. Alternatively or additionally, at least a portion of the oxygen containing gas stream from the electrolysis cell is fed to the syngas stage as said third feed. This provides an efficient source of the first and third feeds.

In a preferred aspect, all of the hydrogen in the first feed and all of the oxygen in the third feed is produced by electrolysis. In this way, the hydrogen and oxygen required by the plant are produced from steam and electricity. Furthermore, if the power is produced from renewable energy sources only, the hydrogen and oxygen in the first and third feeds, respectively, are produced without fossil feedstock or fuel.

Preferably, the water or steam supplied to the electrolytic cell is obtained from one or more units or stages in the apparatus. The use of an electrolytic cell may be combined with any of the embodiments described in this document.

Additional aspects

Optionally, the apparatus may comprise a sixth feed comprising hydrogen to the synthesis gas stream upstream of the synthesis stage. The sixth feed may have the same composition as the first feed comprising hydrogen, i.e. the sixth feed consists essentially of hydrogen and more than 75%, e.g. more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of the feed may be hydrogen.

If desired, the sixth feed can be used to adjust the syngas composition (e.g., H) in the syngas stream₂the/CO ratio). In a preferred aspect, at least a portion of the hydrogen-containing stream from the electrolysis cell is fed into the synthesis gas stream upstream of the synthesis stage as said sixth hydrogen feed. This provides additional opportunities for a system that does not require additional external gas input and allows for final adjustment of the gas composition upstream of the synthesis stage.

The composition of the syngas from the syngas stage can be adjusted by other means. For example, the plant may further comprise a hydrogen removal section between the synthesis gas stage and the synthesis stage arranged to remove at least a portion of the hydrogen from the synthesis gas stream. In this case, at least a portion of the hydrogen removed from the synthesis gas stream in the hydrogen removal stage may be compressed and supplied to the synthesis gas stage as the portion of the first feed. The hydrogen removal unit may be, but is not limited to, a Pressure Swing Adsorption (PSA) unit or a membrane unit.

Furthermore, the plant may further comprise a carbon dioxide removal section between the synthesis gas stage and the synthesis stage arranged to remove at least a portion of the carbon dioxide from the synthesis gas stream. In this case, at least a portion of the carbon dioxide removed from the syngas stream in the carbon dioxide removal stage may be compressed and supplied to the syngas stage as part of the second feed. The carbon dioxide removal unit may be, but is not limited to, an amine-based unit or a membrane unit.

The exhaust stream may be treated to remove one or more components or to alter the chemistry of one or more components prior to being fed to the syngas stage. The tail gas, for example when it is a fischer-tropsch tail gas, may comprise olefins. At high temperatures, olefins increase the risk of carbon deposition and/or metal dusting. Accordingly, the plant may further comprise a hydrogenator disposed in the fischer-tropsch tail gas recycle stream. The hydrogenator is arranged to hydrogenate said fourth feed prior to entering the syngas stage. In this way, olefins can be efficiently converted to saturated hydrocarbons before entering the syngas stage.

The waste or partial waste stream that is not recycled to the syngas stage or used for other purposes may be used to generate additional syngas in a separate syngas generator. Such syngas generators may include techniques known in the art, such as ATR, steam reforming (SMR), and/or adiabatic prereforming, although other techniques are also known. This additional syngas may be fed to the synthesis stage. For example, tail gas from a fischer-tropsch synthesis stage may be converted to additional synthesis gas by means known in the art, including for example hydrogenation, followed by water gas shift and autothermal reforming.

Method

A method for producing a product stream is provided, the method comprising the steps of:

-providing a device as defined herein;

-supplying a first feed comprising hydrogen to a synthesis gas stage;

-supplying a second feed comprising carbon dioxide to the synthesis gas stage;

-supplying a third feed comprising oxygen to the ATR section; and

-converting the first, second, third and optionally fourth feeds into a synthesis gas stream in the synthesis gas stage and feeding the synthesis gas stream to the synthesis stage;

-converting the synthesis gas stream in the synthesis stage into at least a product stream and a hydrocarbon-containing off-gas stream; and

-optionally, feeding at least a portion of said hydrocarbon-containing off-gas stream (3b) or at least a portion of said product stream as a fourth feed comprising hydrocarbons to the syngas stage upstream of said ATR section and preferably between the methanation section and/or reverse water-gas shift section (rWG) section and said ATR section.

All aspects relating to the apparatus described above apply equally to the method of using the apparatus. The term "feed" when applied to the process of the present invention means to provide a stream of the gas to an appropriate stage, reactor or unit. In particular, the following aspects are noted which are particularly important for the process of the invention:

-converting the synthesis gas in the synthesis stage into at least a product stream and optionally a hydrocarbon-containing off-gas stream.

-feeding at least a portion of the hydrocarbon-containing off-gas section as a fourth feed comprising hydrocarbons to the syngas stage upstream of the ATR section and preferably between the methanation section and/or reverse water-gas shift section (rWG) section and the ATR section.

-the synthesis stage may be a fischer-tropsch (F-T) stage arranged to convert the synthesis gas stream into a hydrocarbon-containing off-gas stream in the form of at least a hydrocarbon product stream and a F-T tail gas stream.

The electrolysis cell may be located upstream of the synthesis gas stage and the process may further comprise converting water or steam into at least a hydrogen containing gas stream and an oxygen containing gas stream. The method may further comprise the steps of; at least a portion of said hydrogen-containing gas stream from the electrolysis cell is supplied to the synthesis gas stage as said first hydrogen feed and/or at least a portion of said oxygen-containing gas stream from the electrolysis cell is supplied to the synthesis gas stage as said fourth oxygen feed. The method may further comprise obtaining water or steam supplied to the electrolytic cell, the water or steam being obtained as condensate or steam from one or more units or stages in the hydrocarbon plant.

Detailed description of the drawings

FIG. 1 shows a schematic layout of a first embodiment of the apparatus

A Synthesis gas stage

B synthesis stage

1 first feed (containing hydrogen) to Synthesis gas stage (A)

2 second feed (comprising carbon dioxide) to the Synthesis gas stage (A)

3 third feed (containing oxygen) to the Synthesis gas stage (A)

100 Synthesis gas product from Synthesis gas stage (A)

500 products from Synthesis stage (B)

Fig. 1a shows a schematic view of a first embodiment of the apparatus, including the recycle of a hydrocarbon-containing stream as a fourth feed comprising hydrocarbons. The reference numbers apply to fig. 1, plus:

4a part of the fourth feed from the synthesis stage to the synthesis gas stage (A) (e.g. tail gas from F-T)

4b Another part of the fourth feed from the Synthesis stage to the Synthesis gas stage (A) (for example the LPG stream from F-T)

4c Another part of the fourth feed from the Synthesis stage to the Synthesis gas stage (A) (for example a naphtha stream from F-T)

Fig. 2 shows a schematic layout of another embodiment of the plant, wherein the syngas stage comprises a methanation section (II) and an ATR section (I). The effluent from the methanation stage (II) is sent to the ATR stage (I). The reference numerals are the same as in the previous figures, with the addition of:

(I) ATR section

(II) methanation section

30 effluent from the methanation stage (II) to the ATR stage (I)

Fig. 2a shows a variation of the schematic layout depicted in fig. 2. In this embodiment of the plant, the hydrocarbon feed is treated in a pre-reforming section (Ia) and then fed to a methanation section (II) followed by an ATR section (I). A fifth feed steam (5) is introduced into the pre-reforming section. The reference numerals are the same as in the previous figures, with the addition of:

(Ia) Pre-reforming section

1a part of the first feed to the prereforming stage (Ia)

1b part of the first feed to the ATR section (I)

20 Pre-reformed hydrocarbons to methanation section (II)

5 fifth feed (steam)

Fig. 2b shows a schematic layout of another embodiment of the plant, wherein the syngas stage comprises a pre-reforming section (Ia), a methanation section (II) plus ATR section (I), and steam addition to methanation section (II) (5b) and to pre-reforming section (5 a). The effluent from the methanation stage (II) is sent to the ATR stage (I). The reference numerals are the same as in the previous figures, with the addition of:

5a part of the fifth feed to the prereforming stage (Ia)

5b part of the fifth feed to the methanation section (II)

Fig. 2c shows a schematic layout of another embodiment of the plant, wherein the syngas stage comprises a pre-reforming section (Ia), a methanation section (II) and an ATR section (I), and wherein the methanation section (II) and ATR section (I) are arranged in parallel. The reference numerals are the same as in the previous figures, with the addition of:

31 first Synthesis gas stream from methanation section (II)

50 second syngas stream from ATR section (II)

100 combined syngas stream

Fig. 3 shows a schematic layout of another embodiment of the plant, wherein the syngas stage comprises a pre-reforming section (Ia), an rWGS section (III) plus an ATR section (I). The reference numerals are the same as in the previous figures, with the addition of:

(III) rWGS section

1c part of the first feed to rWGS section (III)

10 Pre-reformed Hydrocarbon to ATR section (I)

40 effluent from rWGS section (III) to ATR section (I)

Fig. 3a shows a schematic layout of another embodiment of the plant, wherein the syngas stage comprises a rWGS section (III) plus an ATR section (I). In this arrangement, the rWGS section (III) and the ATR section (I) are connected in parallel with one another. The reference numerals are the same as in the previous figures, with the addition of:

41 first syngas from rWGS section (III)

50 second syngas stream from ATR section (I)

Fig. 3b shows a schematic layout of another embodiment of the hydrocarbon plant according to fig. 3 a. In the arrangement of fig. 3b, the syngas stream 50 from the ATR section (I) is arranged to heat the rWGS section (III). The effluent from the ATR stage (I) is cooled by heat exchange with the rWGS stage to a synthesis gas stream 60 and then combined with the synthesis gas stream 41 from the rWGS stage (III).

60 cooled syngas stream from ATR section (I) after cooling in rWGS section (III)

FIG. 4 shows a schematic layout of another embodiment of the plant, in which there is a component recovery stage (C), i.e. hydrogen or more CO, between the synthesis gas stage (A) and the synthesis stage (B)₂Recovery and recycling. The reference numerals are the same as in the previous figures, with the addition of:

c component recovery grade

150 recycle gas from component recovery stage

200 Synthesis gas from component recovery stage

Examples

In this section, the pairs are used to utilize CO-rich feedstocks based on hydrocarbon feeds₂The advantages of the novel process of feeding are quantified and compared with conventional equipment.

In C1, important process parameters for a conventionally designed syngas stage (a) that consumes mostly hydrocarbon feed are shown. The synthesis gas stage comprises an autothermal reforming (ATR) section (I) to which synthesis gas is supplied to synthesis stage (B) for the production of liquid fuel by fischer-tropsch (FT) synthesis. In this example, CO has been maximized in the traditional syngas stage without affecting the integrity of the existing equipment₂. However, the utilization of the internal recycle of the hydrocarbon stream from the synthesis stage (B) is compromised.

In C2-C4, CO is enriched₂Feed (2) and H-rich₂The feed (1) of (2) has been mainly used as a feed. The layout of the synthesis gas stage (a) is based on a methanation section (II) followed by an ATR section. A third feed (3) of oxygen is used in the ATR section (I) together with an internal recycle hydrocarbon stream from a synthesis stage (B) that produces a liquid fuel based on fischer-tropsch synthesis.

TABLE 1

In Table 1, relative CO₂The emissions are based on CO relative to C1₂And (4) estimating the emission amount. As can be seen from C2-C4, no hydrocarbon combustion occurs and syngas stage (A) has no CO₂And (5) discharging. In addition, the CO-rich gas is utilized₂Can achieve similar or even better feeding into the synthesis gas in the synthesis gas stage (A)And (4) converting CO. The examples also show that the layout is flexible enough to produce different H's suitable for the downstream synthesis stage (B)₂Syngas in a/CO ratio.

The following numbered aspects are provided:

an apparatus, the apparatus comprising:

a. a synthesis gas stage comprising a methanation section and/or a reverse water gas shift (rWGS) section, and an autothermal reforming (ATR) section, and

b. a synthesis stage;

the apparatus comprises:

-a first feed comprising hydrogen to a synthesis gas stage;

-a second feed comprising carbon dioxide to the synthesis gas stage;

-a third feed comprising oxygen to the ATR section;

wherein the synthesis gas stage is arranged to provide a synthesis gas stream and to supply the synthesis gas stream to the synthesis stage; and wherein the apparatus does not include an external hydrocarbon feed.

The plant according to aspect 1, wherein the syngas stage comprises a methanation section (II) and/or a reverse water gas shift (rWGS) section (III) arranged upstream of the autothermal reforming (ATR) section (I).

Aspect 3. the apparatus of aspect 1, wherein the syngas stage comprises a methanation section (II) and/or a reverse water gas shift (rWGS) section (III) arranged in parallel with an autothermal reforming (ATR) section (I).

Aspect 4. the apparatus according to any of the preceding aspects, wherein a synthesis stage is arranged to convert the synthesis gas stream into at least a product stream, and optionally a hydrocarbon-containing waste gas stream.

The apparatus according to aspect 5. the apparatus according to aspect 4, wherein at least a portion of the hydrocarbon-containing offgas stream or at least a portion of the product stream is fed to the syngas stage as a fourth feed comprising a hydrocarbon upstream of the ATR section, preferably between the methanation section and/or reverse water gas shift (rWGS) section and the ATR section.

Aspect 6. the plant of any preceding aspect wherein the synthesis gas stream is fed directly from the synthesis stage to the synthesis stage.

Aspect 7. the apparatus of any of aspects 1-6, wherein the apparatus comprises a post-conversion stage between the syngas stage and the synthesis stage, and a CO-containing stream to the post-conversion stage₂Said stream comprising CO₂Is arranged to mix with the synthesis gas stream between the synthesis gas stage (a) and the post-conversion stage.

The plant of any of the preceding aspects, further comprising a fifth feed of steam to the syngas stage.

The apparatus of aspect 9. according to any of the preceding aspects, wherein the syngas stage comprises a methanation section and an autothermal reforming (ATR) section.

The apparatus according to any one of the preceding aspects, wherein part or all of the first feed is fed to the methanation section; and part or all of the second feed is fed to the methanation section.

The apparatus of any preceding aspect, wherein the methanation section comprises two or more methanation units, for example three or more methanation units.

Aspect 12 the apparatus of aspect 11, wherein multiple portions of the first feed comprising hydrogen are fed separately to different methanation units in the methanation section; or the first feed comprising hydrogen is all fed together to the methanation unit located most upstream in the methanation section.

Aspect 13. the apparatus of any of aspects 11-12, wherein multiple portions of the second feed comprising carbon dioxide are fed separately to different methanation units in a methanation section; or the second feed comprising carbon dioxide is all fed together to the methanation unit located most upstream in the methanation section.

Aspect 14. the apparatus according to any of aspects 11-13, wherein multiple portions of the third feed comprising hydrocarbon are separately fed to different methanation units in the methanation section; or a third feed comprising hydrocarbons is all fed together to one methanation unit in the methanation section.

Aspect 15. the apparatus according to any of aspects 11-14, wherein a portion of the effluent from one methanation unit is cooled and recycled to the inlet of the methanation unit and/or to the inlet of any additional methanation unit upstream of the one methanation unit.

The plant according to any of the preceding aspects, wherein the syngas stage comprises an inverse water gas shift (rWGS) section and an autothermal reforming (ATR) section.

The apparatus according to any one of the preceding aspects, wherein part or all of the first feed is fed to the rWGS section; and part or all of the second feed is fed to the rWGS section.

The apparatus according to any preceding aspect, wherein the rWGS section comprises two or more rWGS units, for example three or more rWGS units.

The apparatus of aspect 19. the apparatus of aspect 18 wherein multiple portions of the first feed comprising hydrogen are fed to different rWGS units in the rWGS section, respectively; or the first feed containing hydrogen is all fed together to the inverse WGS unit located most upstream in the rWGS section.

Aspect 20 the apparatus of any one of aspects 18-19, wherein multiple portions of the second feed comprising carbon dioxide are fed to different rWGS units in the rWGS section, respectively; or a second feed containing carbon dioxide is all fed together to the rWGS unit located furthest upstream in the rWGS section.

Aspect 21. the apparatus of any preceding aspect, wherein the synthesis gas stream at the synthesis stage inlet has a pressure in the range of 1.00 to 4.00; preferably a hydrogen/carbon monoxide ratio in the range of from 1.50 to 3.00, more preferably from 1.50 to 2.10.

The apparatus according to any one of the preceding aspects, wherein the syngas stream at the outlet of the ATR section has a modulus as defined above in the range 1.90-2.30.

Aspect 23. the apparatus according to any one of the preceding aspects, wherein H is provided at the apparatus inlet₂:CO₂The ratio is 1.0 to 9.0, preferably 2.5 to 8.0, more preferably 3.0 to 7.0.

Aspect 24. the plant according to any of the preceding aspects, wherein the synthesis stage is a fischer-tropsch (F-T) stage, and wherein H is provided at the plant inlet₂:CO₂The ratio is in the range of 1.0 to 9.0, preferably 2.5 to 8.0, more preferably 3.0 to 7.0.

Aspect 25. the apparatus of any preceding aspect, wherein the first feed consists essentially of hydrogen, i.e. more than 75%, such as more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of the first feed is hydrogen.

Aspect 26. the apparatus according to any of the preceding aspects, wherein the second feed consists essentially of carbon dioxide, i.e. more than 75%, such as more than 85%, preferably more than 90%, more preferably more than 95%, even more preferably more than 99% of the second feed is carbon dioxide.

Aspect 27. the apparatus according to any one of the preceding aspects, wherein the third feed consists essentially of oxygen, i.e. more than 75%, such as more than 90% or more than 95%, such as more than 99% of the third feed is oxygen.

Aspect 28. the apparatus of any of aspects 5-27, wherein the fourth feed further comprises CO₂And/or CO and/or H₂。

Aspect 29. the apparatus of any of the preceding aspects, wherein the third feed further comprises steam.

An aspect 30. the plant according to any of the preceding aspects, wherein the synthesis stage is a fischer-tropsch (F-T) stage arranged to convert the synthesis gas into a hydrocarbon-containing off-gas stream in the form of at least a hydrocarbon product stream and a F-T tail gas stream.

An aspect 31. the apparatus according to any preceding aspect, wherein the synthesis stage is a fischer-tropsch (F-T) stage arranged to convert the synthesis gas stream into at least a hydrocarbon product stream, i.e. a diesel stream; and/or an LPG and/or naphtha product stream and wherein at least a portion of the LPG and/or naphtha product stream is fed to a synthesis gas stage.

Aspect 32. the apparatus of aspect 31, wherein multiple portions of the portion of the LPG and/or the naphtha product stream to a syngas stage are fed separately to different methanation units in a methanation section; or the portion of the LPG and/or naphtha product stream going to the syngas stage is fed all together to one methanation unit in the methanation section.

Aspect 33. the apparatus of any of aspects 1-28, wherein the synthesis stage comprises a methanol synthesis stage arranged to provide at least a methanol product stream and a methanol off-gas stream, wherein at least a portion of the methanol off-gas stream is fed to the synthesis stage.

Aspect 34 the plant of aspect 33, wherein the synthesis stage further comprises a methanol-to-gasoline (MTG) synthesis stage arranged to receive a methanol product stream from the methanol synthesis stage and convert it into at least a gasoline stream and an LPG product stream, and wherein optionally a portion of the LPG product stream is supplied to the synthesis stage.

Aspect 35. the apparatus according to any one of the preceding aspects, wherein when the LPG and/or naphtha product stream is fed to the synthesis gas stage, the apparatus further comprises a pre-reforming section upstream of the synthesis gas stage, arranged in the LPG and/or naphtha product stream, and wherein the steam feed is arranged to be mixed with the LPG and/or naphtha product stream prior to being fed to the pre-reforming section.

The apparatus according to any one of the preceding aspects, wherein the exhaust from the ATR section is arranged to heat the pre-reforming section.

Aspect 37. the apparatus according to any one of the preceding aspects, further comprising an electrolysis cell arranged to convert water or steam into at least a hydrogen-containing gas stream and an oxygen-containing gas stream, wherein at least a portion of the hydrogen-containing gas stream from the electrolysis cell is supplied to the synthesis gas stage as part or all of the first feed and/or wherein at least a portion of the oxygen-containing gas stream from the electrolysis cell is supplied to the synthesis gas stage as part or all of the third feed.

Aspect 38 the apparatus of aspect 37, wherein the water or steam supplied to the electrolytic cell is obtained from one or more units or stages in the apparatus.

Aspect 39. the apparatus of any preceding aspect, comprising a sixth feed comprising hydrogen supplied to the synthesis gas stream upstream of the synthesis stage.

Aspect 40 the apparatus of aspect 39 wherein at least a portion of the hydrogen-containing stream from the electrolysis cell is fed as the sixth feed comprising hydrogen into the synthesis gas stream upstream of the synthesis stage.

Aspect 41. the apparatus of any of aspects 5-40, wherein the apparatus further comprises a hydrogenator arranged to hydrogenate the fourth feed prior to entering the syngas stage.

Aspect 42. the apparatus of any preceding aspect, further comprising a hydrogen removal section located between the synthesis gas stage and the synthesis stage and arranged to remove hydrogen from the synthesis gas stream.

Aspect 43 the plant of aspect 42 wherein at least a portion of the hydrogen removed from the synthesis gas stream in the hydrogen removal stage is compressed and supplied to the synthesis gas stage as at least a portion of the first feed.

An aspect 44. the plant of any preceding aspect, further comprising a carbon dioxide removal section located between the synthesis gas stage and the synthesis stage and arranged to remove carbon dioxide from the synthesis gas stream.

Aspect 45 the plant of aspect 44 wherein at least a portion of the carbon dioxide removed from the synthesis gas stream in the carbon dioxide removal stage is compressed and supplied to the synthesis gas stage as at least a portion of the second feed.

The apparatus of any preceding aspect, wherein the syngas stage further comprises an inverse water gas shift (rWGS) section and a methanation section; and wherein an inverse water gas shift (rWGS) section is arranged upstream of the methanation section and the methanation section is arranged upstream of the ATR section.

Aspect 47. the apparatus of any preceding aspect, wherein

-the synthesis gas stage (a) comprises an inverse water gas shift (rWGS) section (III) arranged in parallel with said ATR section (I);

-wherein at least a part of the first feed (1) and at least a part of the second feed (2) are arranged to be fed to a rWGS section (III) and the rWGS section (III) is arranged to convert the at least a part of the first feed (1) and at least a part of the second feed (2) into a first synthesis gas stream (40);

-wherein a third feed (3) comprising hydrocarbon and a fourth feed (4) comprising oxygen are arranged to be fed to the ATR section (I); and wherein the ATR section (I) is arranged to convert the third feed comprising oxygen (3) and the fourth feed comprising hydrocarbons (4) into a second synthesis gas stream (50);

-wherein the first syngas stream (41) from the rWGS section (III) is arranged to be combined with the second syngas stream (50) from the ATR section (I); and the combined syngas stream (100) is arranged to be fed to a synthesis stage (B).

Aspect 48. the apparatus according to aspect 47, wherein the second syngas stream (50) from the ATR section (I) is arranged to provide at least part of the energy required for the endothermic reaction in the rWGS section (III) before being combined with the first and second syngas streams.

Aspect 49 the apparatus of any one of aspects 1-46, wherein

-the synthesis gas stage (a) comprises a methanation section (II) arranged in parallel with the ATR section (I);

-wherein at least a portion of the first feed (1) and at least a portion of the second feed (2) are arranged to be fed to a methanation section (II) and the rWGS section (III) is arranged to convert the at least a portion of the first feed (1) and at least a portion of the second feed (2) into a first synthesis gas stream (31);

-wherein a third feed (3) comprising hydrocarbon and a fourth feed (4) comprising oxygen are arranged to be fed to the ATR section (I); and wherein the ATR section (I) is arranged to convert the third feed comprising oxygen (3) and the fourth feed comprising hydrocarbons (4) into a second synthesis gas stream (50);

-wherein the first syngas stream (31) from the methanation section (II) is arranged to be combined with the second syngas stream (50) from the ATR section (I); and the combined syngas stream (100) is arranged to be fed to a synthesis stage (B).

Aspect 50. a method for producing a product stream, the method comprising the steps of:

-providing a device as defined in any of the preceding aspects;

-supplying a first feed comprising hydrogen to a synthesis gas stage;

-supplying a second feed comprising carbon dioxide to the synthesis gas stage;

-supplying a third feed comprising oxygen to the ATR section;

-converting said first, second, third and fourth feeds into a synthesis gas stream in said synthesis gas stage and feeding said synthesis gas stream to the synthesis stage;

-converting said synthesis gas stream in said synthesis stage into at least a product stream and a hydrocarbon-containing waste gas stream; and

-feeding at least a portion of the hydrocarbon-containing off-gas stream or at least a portion of the product stream to a syngas stage upstream of the ATR section (I) and preferably between a methanation section and/or a reverse water gas shift (rWGS) section and the ATR section as a fourth feed comprising a hydrocarbon.

Aspect 51. the process of aspect 50, wherein the synthesis stage is a fischer-tropsch (F-T) stage arranged to convert the synthesis gas stream into a hydrocarbon-containing off-gas stream in the form of at least a hydrocarbon product stream and a F-T tail gas stream.