LU103148B1 - Process and plant for the synthesis of methanol - Google Patents

Abstract

The invention relates to a method and a plant for the synthesis of methanol (1), wherein a hydrogen stream (35) with external hydrogen is fed to a synthesis gas stream (2), wherein a portion of a residual gas stream (15) discharged from a methanol reactor arrangement (4), and/or a recovery stream (6) optionally fed to a hydrogen recovery arrangement (5), and/or a stream (71) downstream of the hydrogen recovery arrangement (5) is branched off and fed to a synthesis gas reactor arrangement (13) as a recycle stream (40). This concept makes it possible to significantly increase the efficiency of methanol production. Furthermore, unwanted emissions can be reduced and thus the ecological balance of the method or plant can be improved.

Description

' 06.06.2023

LU103148

Process and plant for the synthesis of methanol

The invention relates to a process for the synthesis of methanol according to the preamble of claim 1 and a plant for the synthesis of methanol according to the

Preamble of claim 21.

Methanol is an important basic chemical that is used for the synthesis of higher or functionalized hydrocarbon compounds and as a solvent. Methanol is used, for example, as a starting material for the production of formaldehyde, formic acid and acetic acid.

The production of methanol is usually carried out in a reactor arrangement of a

Plant for the synthesis of methanol (methanol reactor arrangement), to which methanol reactor arrangement a synthesis gas stream containing hydrogen and carbon oxides is fed and in which an (exothermic) chemical reaction to

Production of methanol takes place. Synthesis gas can be used in one of the methanol

Reactor arrangement can be produced in a synthesis gas reactor arrangement upstream of the process. Primarily, carbon-containing gases (i.e. carbon-containing energy sources) such as natural gas or biogas are converted into synthesis gas.

Such carbon-containing energy sources often contain methane. The synthesis gas reactor arrangement and the methanol reactor arrangement can together form a plant for the synthesis of methanol.

To convert the carbon-containing energy source into synthesis gas, the synthesis gas reactor arrangement mentioned can be based on the principle of autothermal reforming or partial oxidation and corresponding

reactors (e.g. a reforming reactor or oxidation reactor). Likewise, the synthesis gas reactor arrangement can include a steam reformer. The use of a steam reformer can be achieved by adding CO, or

Using a CO2-rich carbon-containing energy source such as biogas can be advantageous. This is generally known from the state of the art.

Processes for the synthesis of methanol are described, for example, in the publications WO 2020/058859 A1, WO 2007/108014 A1, DE 10 2016 213 668 A1, WO

? 06.06.2023 2013/144041 A1, WO 2020/048809 A1, DE 10 2019 124 078 A1, US LU103148 2019/0185887 A1 and WO 2020/249923 A1.

Depending on the way in which the synthesis gas stream is obtained and depending on which energy source forms the basis for the synthesis gas, the proportion of hydrogen in the synthesis gas stream obtained can be lower than is actually desired. For example, the proportion of hydrogen can be sub-stoichiometric. To improve the stoichiometry, it is therefore often expedient to recover unreacted hydrogen from a residual gas of the reactor arrangement using a hydrogen recovery arrangement and to

Hydrogen is returned to the reactor arrangement. Such a hydrogen-rich stream returned to the reactor arrangement can compensate to a certain extent for the hydrogen deficiency mentioned above caused by the substoichiometry.

It is also known that a hydrogen deficit during the synthesis of methanol can be (at least partially) compensated by adding external hydrogen. The external hydrogen can come from fossil sources or be generated renewably and added to the synthesis gas stream.

Both in methanol synthesis plants with integrated hydrogen recovery and in plants with an external hydrogen supply, purging

Gas that must be removed from the synthesis or recovery cycle to avoid excessive accumulation of inert components such as nitrogen and methane. Such purge gas is usually used as fuel

Gas is burned off. To ensure a satisfactory ecological balance of such synthesis plants, it is desirable to reduce the amount of purge or

To keep the fuel gas consumption as low as possible.

The invention is based on the object of providing a process and a plant for the synthesis of methanol, with which on the one hand a substoichiometric presence of hydrogen can be compensated and on the other hand the proportion of purge or fuel gas produced can be reduced. A particular object of the invention is therefore on the one hand to increase the efficiency or yield in the

To increase methanol synthesis and, on the other hand, to improve environmental friendliness and the ecological balance.

’ 06.06.2023

LU103148

This object is achieved by a method having the features of claim 1 and a system having the features of claim 21.

Firstly, the invention relates to a process for the synthesis of methanol, wherein a carbon-containing energy carrier stream is fed to a synthesis gas reactor arrangement for obtaining a synthesis gas stream with hydrogen and carbon oxides. Optionally, the synthesis gas stream can be fed to a synthesis gas compressor for increasing the pressure. According to the invention, the synthesis gas stream, optionally the pressure-increased synthesis gas stream, is fed at least partially to a first reactor stage of a

Methanol reactor arrangement is fed, optionally subsequently unreacted residual gas from the first reactor stage is fed to a second reactor stage of the methanol reactor arrangement for at least partial conversion into methanol, wherein a residual gas stream with unreacted carbon oxides is obtained from the methanol reactor arrangement, which residual gas stream is fed to a recycling compressor for increasing the pressure of the residual gas stream, wherein the pressure-increased residual gas stream is fed to the methanol reactor arrangement for at least partial conversion into methanol, wherein optionally an unreacted

A recovery stream comprising residual gas from the first and/or second reactor stage is fed to a hydrogen recovery arrangement for obtaining a H-recycle stream, which H-recycle stream contains unreacted hydrogen from the unreacted residual gas from the first reactor stage and/or from the unreacted

Residual gas from the second reactor stage, whereby the unreacted hydrogen of the

H recycle stream is fed back to the first reactor stage for at least partial conversion into methanol. The process is characterized in that a hydrogen stream with external hydrogen is fed to one of the streams upstream or downstream of the synthesis gas reactor arrangement, and that part of the residual gas stream, and/or the optional recovery stream, and/or a stream downstream of the hydrogen recovery arrangement is branched off and fed to the synthesis gas reactor arrangement as a recycle stream. An embodiment may be preferred in which the water stream with external hydrogen is fed to the synthesis gas stream (downstream of the synthesis gas reactor arrangement).

° 06.06.2023

The proposed process is used for the synthesis of methanol. In the proposed process, a carbon-containing energy carrier stream of a

Synthesis gas reactor arrangement for producing a synthesis gas stream with hydrogen and carbon oxides. The synthesis gas stream therefore contains hydrogen, carbon monoxide and carbon dioxide and can also contain other components such as nitrogen and noble gases. The synthesis gas stream can also be referred to as a fresh gas stream.

The synthesis gas stream can be fed to a synthesis gas compressor to increase the pressure. The synthesis gas compressor can be designed as a single or multi-stage system. The (optionally pressure-increased) synthesis gas stream is fed at least partially to a first

reactor stage of a methanol reactor arrangement. It is preferred that the (optionally pressure-increased) synthesis gas stream is fed essentially completely to the first

reactor stage. It is also possible that part of the synthesis gas stream is diverted beforehand. The feature of “at least partial conversion into methanol” is based on the fact that an unreacted residue of

Educts can escape from the methanol reactor arrangement and therefore the conversion cannot be completed. The methanol reactor arrangement can have several (in particular two, but also more than two) reactor stages or only a single reactor stage. If the methanol reactor arrangement does not have several reactor stages, the first reactor stage is the only reactor stage of the methanol reactor arrangement. The first reactor stage of the

Methanol reactor arrangement is the reactor stage of the methanol reactor arrangement to which the synthesis gas stream is at least partially fed before it or a remaining residual gas stream is fed to another, e.g. a second, reactor stage. The first reactor stage is in this respect the reactor stage of the methanol reactor arrangement that is located first in terms of process technology. This circumstance corresponds to the possible designation of the synthesis gas stream as a fresh gas stream. Each individual reactor stage of the methanol reactor arrangement can have several individual reactors that are connected in parallel to one another in terms of process technology for the

methanol synthesis.

In the proposed process, a residual gas stream containing unreacted carbon oxides is obtained from the methanol reactor arrangement, which residual gas stream is fed to a recycle compressor to increase the pressure of the

) 06.06.2023

The residual gas stream can also contain unreacted hydrogen or even methane (which has not previously been converted to synthesis gas). The residual gas stream can also contain inert components such as nitrogen or noble gases. If the methanol reactor arrangement has more than one reactor stage (e.g. two reactor stages), this residual gas stream can be recovered after any reactor stage. A residual gas stream can also be present between the first reactor stage and the second reactor stage. An unreacted

Substance/ingredient or an unreacted component is here and below a

Substance (in gaseous state) which serves as a reactant for the

Methanol synthesis was fed to a reactor stage of the methanol reactor arrangement, in particular the first reactor stage, and then exited the reactor stage without having participated in a reaction to synthesize methanol. An unreacted substance can be a substance that was fed to the synthesis gas reactor arrangement but not converted there. The recycle compressor serves to circulate the majority of the unreacted residual gas through the methanol reactor arrangement. The process further provides that the pressure-increased residual gas stream is fed to the methanol reactor arrangement for partial conversion into methanol. This is therefore a return of the now pressure-increased residual gas stream to the methanol reactor arrangement from which the residual gas stream was obtained.

In an optional variant, unreacted residual gas from the first and/or second reactor stage can be fed in the form of a recovery stream to a hydrogen recovery arrangement for obtaining an H recycle stream, which H recycle stream comprises unreacted hydrogen from the unreacted residual gas from the first reactor stage and/or from the unreacted residual gas from the second reactor stage, wherein the unreacted hydrogen from the H recycle stream is fed again to the first reactor stage for at least partial conversion into methanol. Usually only a partial stream of the unreacted residual gas (e.g. from the first and/or second reactor stage) is fed to the hydrogen recovery arrangement as a recovery stream. The recovery stream can be obtained from the unreacted residual gas from the first and/or second reactor stage, for example by branching off. This is because a partial stream of the recovery stream can be fed to the synthesis gas reactor arrangement as a recycle stream according to the invention.

° 06.06.2023

The H recycle stream comprises unreacted hydrogen from the unreacted residual gas (of the first and/or second reactor stage), which unreacted hydrogen of the H recycle stream is fed again to the first reactor stage for at least partial conversion into methanol. It may be that the unreacted hydrogen of the H recycle stream is only a part of the total unreacted hydrogen of the first and/or second reactor stage and/or only a part of the total unreacted hydrogen of the unreacted residual gas. The unreacted hydrogen of the H recycle stream can be fed again to the first reactor stage both directly and indirectly. In the case of indirect feeding, the unreacted hydrogen is initially fed to other devices.

The proposed method is characterized in that a hydrogen stream with external hydrogen is fed to one of the streams upstream or downstream of the synthesis gas reactor arrangement, and that part of the residual gas stream and/or the optional recovery stream is branched off and fed to the synthesis gas reactor arrangement as a recycle stream. A preferred embodiment may be one in which the water stream with external hydrogen is fed to the synthesis gas stream (downstream of the synthesis gas reactor arrangement). However, the external hydrogen does not necessarily have to be fed to the synthesis gas stream (i.e. downstream of the synthesis gas reactor arrangement); it may also be provided that the external hydrogen is fed into the system before the synthesis gas is produced.

If external hydrogen is supplied, the hydrogen recovery arrangement mentioned above can be reduced in size or even eliminated completely.

Compared to a process without the addition of external hydrogen, when external hydrogen is supplied, a smaller amount or no internal hydrogen needs to be produced by a hydrogen recovery system.

Both if a hydrogen recovery system is dispensed with completely or if the hydrogen recovery system is reduced in size, the removal of purge gas is necessary in order to avoid an excessive accumulation of inert components such as nitrogen and methane. A hydrogen recovery system that is small in size or

! 06.06.2023 Not doing so can lead to the need to remove purge gas LU103148 or fuel gas, but also to a larger residual gas flow.

To avoid this, the proposed invention provides for a part of the residual gas stream, and/or the optional recovery stream, and/or one of the

hydrogen recovery arrangement and to feed it to the synthesis gas reactor arrangement as a recycle stream. This has the effect that the residual gas flow fed to the recycle compressor and then again to the methanol reactor arrangement is reduced (i.e. less unreacted

Residual gas circulates in the methanol reactor arrangement). Unreacted residual gas from the first reactor stage and/or unreacted residual gas from the optional second reactor stage is thus fed back to the methanol reactor arrangement (i.e. the reactor stages) in a smaller proportion. The proportion of residual gas remaining or circulating in the methanol reactor arrangement is thus reduced. Those components that were not converted to synthesis gas during synthesis gas production (e.g. methane) that entered the synthesis gas stream can be fed back to the synthesis gas reactor arrangement and converted there to synthesis gas. Furthermore, the total proportion of fuel gas produced is reduced by the recirculation, which - since fuel gas is usually burned off - has a positive effect on the ecological balance of methanol synthesis. For example, the residual gas can contain a certain proportion of methane. If this is now fed back to the synthesis gas reactor arrangement instead of being burned off as fuel gas, it can be converted - at least to a certain extent - into synthesis gas and ultimately into methanol. The aforementioned effects can be achieved if only a portion of the residual gas flow is diverted and fed to the synthesis gas reactor arrangement as a recycle stream, but also if only a portion of the recovery stream (this can be optionally provided if a hydrogen recovery arrangement is used) is returned. Since both the recovery stream and the residual gas flow contain unreacted residual gas, the effects described above can be achieved with both recycle variants. A combined recycle of a diverted portion of the residual gas flow and a diverted portion of the

Recovery power can be provided and advantageous.

; 06.06.2023

A “branch” does not necessarily mean a branch in the pipeline, LU103148 but can also be understood as a “feed to” or “line to” (e.g. to the synthesis gas reactor arrangement).

Advantageous embodiments of the invention are described below, including those features of the invention specified in the subclaims.

Further - not specified in the subclaims -

Embodiments or features of the invention are described. All of the further embodiments or features described in the subclaims and the following can specify the invention across category boundaries. Thus, those in connection with the proposed invention

The embodiments or features mentioned in the process (for the synthesis of methanol) also represent embodiments or features of the plant proposed by the invention (for the synthesis of methanol) and vice versa.

The same applies to other categories of claims not mentioned here (e.g. use).

According to a first embodiment of the invention, it can be provided that the

Synthesis gas flow is fed to a heat recovery device for recovering heat from the synthesis gas flow and then to the synthesis gas compressor. It is conceivable that the synthesis gas flow is fed to another device or several other devices between the heat recovery device and the synthesis gas compressor. It should also be noted that the heat recovery device usually represents only one stage of a heat recovery arrangement with several heat recovery devices. In other words, it may be that the synthesis gas flow is fed to only one

Heat recovery device is supplied from several interconnected heat recovery devices.

According to a further embodiment of the proposed method, the unreacted hydrogen of the H recycle stream can be at least partially pressure-increased from the first reactor stage to the point of being fed back into the first reactor stage by the recycle compressor with the unreacted carbon oxides. In other words, at least part of the unreacted hydrogen in the H recycle stream can be pressurized between the outlet of this unreacted

Hydrogen from the first reactor stage and the re-feeding of this un-

’ 06.06.2023 reacted hydrogen to the first reactor stage, a pressure increase can be carried out by LU103148 the recycle compressor. Since the recycle compressor - as already described - increases the pressure of the residual gas stream with unreacted carbon oxides, the pressure increase of the unreacted hydrogen can take place through the recycle compressor together with the unreacted carbon oxides. The unreacted hydrogen of the H recycle stream can be pressure increased essentially completely from the first reactor stage until it is fed back to the first reactor stage by the recycle compressor with the unreacted carbon oxides.

The synthesis gas reactor arrangement, the synthesis gas compressor, the methanol

Reactor assembly, heat recovery device, recycle compressor and hydrogen recovery assembly can be operated by a plant for

Synthesis of methanol may be included.

In principle, the residual gas stream fed to the recycle compressor can have any composition, as long as the residual gas stream contains unreacted carbon oxides in any proportion and optionally unreacted

hydrogen from the recovery stream.

According to a further embodiment of the proposed method, it can be provided that the hydrogen stream, for example from a hydrogen recovery device, is fed to the synthesis gas stream after it has left the heat recovery device. Thus, the

Supply of the hydrogen stream to the synthesis gas stream does not allow for the heat recovery from the synthesis gas stream, which is advantageous for ecological reasons (e.g. by a possible temperature reduction after supply of the hydrogen stream). It is also advantageous that the hydrogen stream is supplied to the synthesis gas stream before it is fed into the synthesis gas compressor. This ensures that a substoichiometric hydrogen content in the synthesis gas stream before the synthesis gas enters the first reactor stage of the methanol

reactor arrangement can be at least partially compensated. The hydrogen flow, as well as the external hydrogen, can in principle be fed into the system at any point, including before the recycle compressor, after the first reactor stage, before the synthesis gas reactor arrangement, etc.

June 6, 2023

According to a further embodiment of the proposed method, unreacted hydrogen from the H recycling stream can be added to the (external) hydrogen stream. In this case, the hydrogen stream is composed of external hydrogen and hydrogen recycled from the recovery stream in the recovery arrangement. Whether hydrogen recovery is required depends largely on the respective

The need for hydrogen recovery depends on the plant design and the amount of hydrogen (or hydrogen content) present in the synthesis gas stream. Furthermore, the need for hydrogen recovery depends on the feed gas used and the amount of hydrogen

available hydrogen. By means of appropriate hydrogen recovery, additional hydrogen can be added to the synthesis gas stream in addition to the external hydrogen via the hydrogen stream mentioned above (which can compensate for any hydrogen deficit).

The hydrogen stream can be pressure-increased by means of a hydrogen compressor before being fed into the methanol reactor arrangement, in particular into the synthesis gas stream. This is advantageous in order to raise the hydrogen stream to the pressure level of the synthesis gas stream if necessary or to achieve a desired

The transport of a hydrogen stream at increased pressure can be advantageous, as this can be done in smaller lines than the transport of a hydrogen stream without increased pressure. It can be advantageous to spatially adjust the pressure of the hydrogen stream just before it is fed to the

Methanol reactor arrangement or to compress it to the synthesis gas stream (i.e. to increase the pressure). From a plant engineering point of view, the transport of hydrogen over short distances is advantageous. The hydrogen compressor can have one or more

compressor units.

According to a further embodiment of a proposed process, it can be provided that the unreacted hydrogen from the H-recycle stream is

Hydrogen stream is supplied via the hydrogen compressor, in particular that the unreacted hydrogen and the external hydrogen are jointly pressure-increased by means of the hydrogen compressor. A joint pressure increase in the hydrogen compressor can have cost advantages.

According to a further embodiment of a proposed method, it can be provided that the external hydrogen is supplied to the hydrogen stream from an electrolysis hydrogen stream which is supplied from an electrolysis arrangement to the

June 6, 2023

Decomposition of water into external hydrogen and oxygen is obtained. LU103148

The electrolysis arrangement can be installed externally to the proposed plant for

The electrolysis hydrogen stream preferably comprises mainly hydrogen. The electrolysis referred to is therefore an electrolysis of water (water electrolysis). In such a

In water electrolysis, water (H,O) is broken down into its components hydrogen (H2) and oxygen (O,) using electrical current. It is particularly advantageous if the electrical current used is generated from renewable energy sources (e.g. wind, sun, biomass, etc.). The oxygen produced during water electrolysis can also be used in the reforming reactor (in the case of

Using autothermal reforming) or in the oxidation reactor (in the case of

Use of partial oxidation) to produce the synthesis gas.

Preferably, the methanol reactor arrangement comprises a first methanol

Separation device for recovering the unreacted residual gas from the first reactor stage and a first crude methanol stream from the first reactor stage. In particular, the first methanol separation device can comprise a first condensation device for recovering the unreacted residual gas from the first reactor stage and the first

crude methanol stream of the first reactor stage by condensation. Optionally, the methanol reactor arrangement can comprise a second methanol separation device for obtaining the unreacted residual gas of the second reactor stage and a second crude methanol stream of the second reactor stage, wherein in particular the second methanol separation device comprises a second condensation device for obtaining the unreacted residual gas of the second reactor stage and the second crude methanol stream of the second reactor stage by condensation. In principle, the first and/or second methanol separation device can be designed in any desired manner. As mentioned, it can be advantageous for the first and/or second methanol separation device to comprise a first or second condensation device.

As already stated, in principle it can be provided that the methanol reactor arrangement comprises only a single (first) methanol reactor stage. However, the methanol reactor arrangement can also have a plurality of reactor stages connected in series for methanol synthesis, in which case

06.06.2023 for example a first reactor stage and a second reactor stage downstream of the first reactor stage in terms of process technology. Each individual reactor stage can have one or more reactors. The reactors of a reactor stage can in particular be arranged in parallel with one another in terms of process technology.

Furthermore, a methanol separation device may be used to recover a respective unreacted residual gas from each of the plurality of reactor stages.

Each reactor stage can be assigned a separate methanol separation device. A common methanol separation device can also be assigned to several or all reactor stages, in which case the reactor stages are connected in parallel. In this case, the term "reactor stage" is not to be understood as referring to "stages" of reactors connected in series in terms of process technology, but rather to "reactors" connected in parallel.

The fact that the first and second reactor stages are connected in series in terms of process technology (the second reactor stage is connected downstream of the first reactor stage) means that residual gas from a reactor stage - unless it is the last reactor stage in a series of several reactor stages - is fed directly or indirectly to the reactor stage connected after it. In the case of a first and second reactor stage, residual gas from the first reactor stage is fed directly or indirectly to the second reactor stage. In principle, the above recycle compressor can be arranged in any way with respect to the plurality of reactor stages. One variant is that the recycle compressor is arranged between two reactor stages in terms of process technology, for example in the case of two reactor stages between the first and second reactor stages. This means that at least part of the unreacted residual gas from a

reactor stage as a residual gas stream and the pressure-increased residual gas stream is then fed to the reactor stage downstream of this reactor stage.

In principle, the H recycle stream mentioned can be conducted in any way as long as at least part of its hydrogen is converted into methanol. According to an advantageous embodiment of the process, it can be provided that the

H-recycle stream is fed to the unreacted residual gas of a reactor stage that is downstream of the first reactor stage (e.g. second). If there are two reactor stages, the unreacted hydrogen from the H-recycle stream can be fed to the unreacted residual gas of the second reactor stage.

June 6, 2023

LU103148

In other words, the unreacted hydrogen of the H recycle stream is treated after feeding together with at least a portion of the unreacted residual gas from a reactor stage other than the first reactor stage. In this way, the H recycle stream “skips” one or more reactor stages after the first reactor stage. The advantage of such an approach is that this

The pressure loss of the H recycle stream due to hydrogen recovery is essentially parallel to the pressure loss of the unreacted residual gas of the downstream (e.g. second) reactor stage in this reactor stage. In other words, the respective pressure of this unreacted residual gas and the H

recycle stream closer together, which in turn reduces the pressure loss that occurs when they are combined by adjusting to the lower pressure level. The H recycle stream can be fed to the recycle compressor with the residual gas stream to increase the pressure.

According to a further embodiment of the method, it can be provided that the residual gas stream is obtained from a reactor stage that is downstream of the first reactor stage in terms of process technology, in particular the second reactor stage. In other words, the residual gas stream fed to the recycle compressor does not originate from the first reactor stage - i.e. the reactor stage to which the synthesis gas stream is at least partially fed directly - but from a downstream reactor stage. Furthermore, the recycle compressor can feed the pressure-increased residual gas stream to the first reactor stage. In principle, the pressure-increased residual gas stream can also be fed to another reactor stage of the

It is also possible for the pressurized residual gas flow to be split and fed to several reactor stages of the plurality of reactor stages.

According to a further embodiment of the proposed method, it can be provided that the residual gas stream is obtained from a reactor stage that is stored last in terms of process technology of the plurality of reactor stages. In the case of two reactor stages, the second reactor stage represents the reactor stage that is stored last. This and the previous variant also make it possible to

to reduce the pressure losses required to combine streams.

June 6, 2023

In principle, the recovery stream can be obtained at any location and from any origin within the methanol reactor arrangement. The recovery stream contains unreacted hydrogen from an unreacted residual gas from the first reactor stage and/or the second reactor stage.

One variant provides that the recovery stream is at least partially diverted from the unreacted residual gas of the first reactor stage. According to another variant, the recovery stream (if two reactor stages are provided) can be diverted from the unreacted residual gas of the second reactor stage. It is also conceivable that the recovery stream is diverted from both the unreacted residual gas of the first reactor stage and the unreacted residual gas of the second reactor stage. It is therefore possible that the recovery stream is at least partially diverted upstream of the recycle compressor in terms of process technology.

Basically, it should be noted that hydrogen recovery from the

Recovery stream and at least partial re-feeding of the H recycle stream to the first reactor stage, the hydrogen content in the first reactor stage can be increased and thus the stoichiometry for methanol synthesis can be improved. The same applies to the case of the feed of external hydrogen into the synthesis gas stream (via the hydrogen stream) and the subsequent feed to the first reactor stage. This also applies to a combination of external hydrogen and recovered hydrogen from the recovery stream.

The synthesis gas reactor arrangement may comprise a reforming reactor or a

Oxidation reactor. In particular, an oxygen-containing stream can be fed to the synthesis gas reactor arrangement to obtain the synthesis gas stream. In particular, it can be provided that in the synthesis gas reactor arrangement the synthesis gas stream is reformed by an autothermal reforming in the

reforming reactor or a partial oxidation in the oxidation reactor from the carbon-containing energy carrier stream.

The synthesis gas reactor arrangement can be used in addition to a reactor for producing the

synthesis gas. The synthesis gas reactor arrangement can have a device for desulfurization of the carbon-containing energy carrier stream, a saturation

06.06.2023 stage for saturating the carbon-containing energy carrier stream with water, a LU103148

Pre-reforming reactor (pre-reformer) for pre-reforming the carbon-containing energy carrier stream and/or a device for heating the carbon-containing energy carrier stream.

In principle, the synthesis gas stream can be obtained from the energy carrier stream in any way. It is preferred that the synthesis gas stream is obtained

Synthesis gas stream an oxygen-containing stream is fed to the synthesis gas reactor arrangement. In principle, the oxygen-containing stream can be fed into the

Oxygen can also contain other components. The oxygen-containing stream can also be ambient air.

In principle, the synthesis gas stream can be converted into a carbon-containing gas by steam reforming (using a steam reformer as the reforming reactor)

The use of a steam reformer can be achieved by adding CO, or using a CO, rich carbonaceous

energy source electricity (such as biogas) may make sense.

A further preferred embodiment of the process is characterized in that in the synthesis gas reactor arrangement the synthesis gas stream is obtained from the carbon-containing energy carrier stream by autothermal reforming, namely in the reforming reactor mentioned. In such autothermal reforming (ATR), catalytic partial oxidation provides the heat required for the endothermic reforming reactions. Compared to pure steam reforming, autothermal reforming offers the

Advantage that the synthesis gas stream can be provided at a higher pressure. Alternatively or additionally, the synthesis gas stream can be obtained in the synthesis gas reactor arrangement by partial oxidation from the carbon-containing energy carrier stream, namely in the oxidation reactor mentioned.

In principle, autothermal reforming can also be carried out with ambient air. However, it is preferred that the oxygen contained in the oxygen-containing stream is obtained from an air separation device to obtain a

oxygen stream is obtained from ambient air. The air separation device can also be set up to obtain a nitrogen stream

06.06.2023. In particular, it may then be the case that the oxygen-containing stream essentially comprises oxygen. In this way, the proportion of inert gases in the methanol synthesis is reduced, so that various devices in the plant can be made smaller. Preferably, the plant for

Synthesis of methanol the air separation device.

According to a further embodiment of the proposed method, the oxygen contained in the oxygen-containing stream can be obtained from the electrolysis arrangement. When external hydrogen is produced by means of water electrolysis, oxygen is also produced due to the chemical reaction underlying this process. Using this oxygen, which is produced anyway, to produce synthesis gas (autothermal reforming or partial oxidation) makes the proposed method particularly efficient and at the same time improves its ecological balance. Otherwise, the oxygen produced would have to be stored for other purposes, passed on or discarded.

According to a further embodiment of the proposed method, it can be provided that the recycle stream of the synthesis gas reactor arrangement is fed upstream of the reforming reactor or the oxidation reactor. This enables the recycle stream and the components contained therein to pass through the reforming reactor (e.g. an autothermal reforming reactor or steam reformer) or the oxidation reactor (for partial oxidation) again. The components contained in the recycle stream, in particular methane, can then pass through the (chemical) processes taking place in the synthesis gas reactor arrangement again and be converted into synthesis gas. If catalysts are used, this allows the components of the recycle stream to come into contact again with the catalysts used to produce synthesis gas.

According to a further embodiment of the proposed process, it can be provided that upstream of the reforming reactor, a

Pre-reforming reactor (pre-reformer) is arranged, whereby the recycle stream is fed to the synthesis gas reactor arrangement between the pre-reforming reactor and the reforming reactor. Since the components of the

recycle stream the pre-reforming reactor already in a previous

06.06.2023, a further passage through the pre-reforming reactor may not be necessary. A further processing in the sense of a

Pre-reforming can therefore be omitted.

In principle, the H recycle stream can have any composition, provided that it contains the unreacted hydrogen from the unreacted residual gas of the first reactor stage. According to a further preferred embodiment of the process, the H recycle stream has a higher molar

proportion of hydrogen than the recovery stream. This refers not only to the unreacted hydrogen from the unreacted residual gas from the first reactor stage, but to the hydrogen in the H recycle stream as a whole. In other words, the hydrogen in the H recycle stream is enriched compared to the recovery stream. It is also preferred that the H recycle stream has a higher molar proportion of hydrogen than the purge stream.

In principle, the hydrogen recovery arrangement can function according to any principle, for example based on a membrane arrangement or a cooling device. According to a further embodiment of the method, the hydrogen recovery arrangement can have a pressure swing adsorption device (PSA) for obtaining the H recycle stream from the recovery stream. In this way, a high recovery of hydrogen in the H

Recycle stream can be achieved. The pressure losses in such a

Pressure swing adsorption device is acceptable. Although a high hydrogen purity is not required in principle in this case, it can still be achieved. It is therefore possible that the H recycle stream essentially contains hydrogen.

According to a further embodiment of the proposed method, it can be provided that the hydrogen recovery arrangement outputs a purge stream, and/or that a purge stream is branched off from the recycle stream, and/or that a purge stream is branched off from the recovery stream, and/or that a purge stream is branched off from the residual gas stream. The

Purge stream is preferably fed to a combustion facility or directed to a flare.

June 6, 2023

According to a further development of the proposed procedure, a LU103148

Ratio of a first mass flow formed by a sum of carbon-containing compounds present in the purge stream relative to a first mass flow formed by a sum of carbon-containing compounds present in the synthesis gas stream.

Compounds formed by the second mass flow can assume a value of 10-> to 0.4, and preferably assume a value of 0.0001 to 0.3, and more preferably assume a value of 0.0005 to 0.21. The first and/or second mass flow can in particular comprise CO, CO,, CH4 and/or methanol as carbon-containing compounds. In particular, the said ratio can assume a value of approximately 0.0005, 0.05 or 0.22, preferably of exactly 0.0005, 0.015 or 0.22. These (low) ratios can embody reduced emissions compared to the prior art. Furthermore, in a process or plant that uses the said connections, the recycle stream in the methanol synthesis can be kept low.

In addition to the described process for the synthesis of methanol, the object underlying the invention is also achieved by a plant for the synthesis of methanol.

A plant for the synthesis of methanol is proposed with a synthesis gas reactor arrangement for obtaining a synthesis gas stream with hydrogen and carbon oxides from a carbon-containing energy carrier stream fed to the synthesis gas reactor arrangement, optionally with a synthesis gas compressor for increasing the pressure of the synthesis gas stream, with a methanol reactor arrangement which has a first reactor stage and optionally a second reactor stage, with a recycle compressor, and optionally with a hydrogen recovery arrangement. The plant also comprises a device for at least partial

Feeding the (optionally pressure-increased) synthesis gas stream into the first reactor stage for at least partial conversion into methanol. The "device" can be a physical device that is designed to at least partially feed the (optionally pressure-increased) synthesis gas stream into the first reactor stage. Such a "device" can be a line, for example. The "device" can include general valve systems, control and regulating systems.

June 6, 2023

The plant may further comprise an optional device for supplying unreacted residual gas from the first reactor stage to the optional second reactor stage for at least partial conversion into methanol. The "device" may be a physical device designed to supply unreacted residual gas from the first reactor stage to the optional second reactor stage. Such a "device" may be, for example, a line.

The “equipment” may include general valve systems, pumping systems, control and regulation systems.

The plant further comprises a device for recovering a residual gas stream from the methanol reactor arrangement containing unreacted carbon oxides. This “device” is understood to mean a physical device used to recover a residual gas stream from the methanol reactor arrangement containing unreacted carbon oxides.

carbon oxides. For example, this could be a methanol separation device including the associated piping system.

The system also includes a device for feeding the residual gas flow into the recycle compressor to increase the pressure of the residual gas flow. The “device” can be a physical device used to feed the

residual gas flow into the recycle compressor. Such a "device" can be, for example, a line. The "device" can contain general

Valve systems, pump systems, control and regulation systems.

The system also includes a device for supplying the pressure-increased

residual gas flow into the methanol reactor arrangement for at least partial conversion into methanol. The "device" can be a physical device that is designed to feed the pressure-increased residual gas flow into the methanol reactor arrangement. Such a "device" can be, for example, a line. The "device" can be general valve systems,

control and regulation systems.

Furthermore, the system can optionally include a device for supplying an unreacted

Residual gas of the first and/or second reactor stage into the hydrogen recovery arrangement for obtaining a H-recycle stream, wherein the H-recycle stream comprises unreacted hydrogen from the unreacted residual gas of the first reactor stage and/or from the unreacted

June 6, 2023

Residual gas from the second reactor stage. The "device" may be a physical device which is designed to feed a recovery stream comprising unreacted residual gas from the first and/or second reactor stage into the hydrogen recovery arrangement. Such a "device" may, for example, be a line. The "device" may include general valve systems, pump systems, control and regulating systems. Furthermore, the system may optionally comprise a device for re-feeding the unreacted

hydrogen from the H recycle stream into the first reactor stage for at least partial conversion into methanol. The “device” may be a physical device used to re-feed the unreacted

hydrogen from the H recycle stream into the first reactor stage. Such a "device" can be, for example, a line. The "device" can include general valve systems, control and regulation systems.

The system is characterized by a device for supplying a hydrogen stream with external hydrogen to one of the streams upstream or downstream of the synthesis gas reactor arrangement. It can be advantageous to supply the hydrogen stream with external hydrogen into the synthesis gas stream. The "device" can be a physical device that is designed to supply a hydrogen stream with external hydrogen into the synthesis gas stream. This "device" can be a line, for example. The "device" can include general valve systems, control and regulation systems.

The “device” may also include a hydrogen compressor.

The facility is further characterized by one or more devices for

Branching off and supplying a portion of the residual gas flow, and/or the optional

recovery stream, and/or a stream downstream of the hydrogen recovery arrangement into the synthesis gas reactor arrangement as a recycle stream. The said “equipment(s)” may be physical

Device(s) designed to divert and supply a portion of the residual gas stream, and/or the optional recovery stream, and/or one of the

Hydrogen recovery arrangement downstream stream into the synthesis gas reactor arrangement as a recycle stream. This "device" can be, for example, a line. The "device" can be general

valve systems, control and regulation systems.

June 6, 2023

The characteristics, advantages and properties of the proposed plant correspond to the characteristics, advantages and properties of the proposed process and vice versa.

Further details, features, objects and advantages of the present invention are explained below with reference to the drawings which only show exemplary embodiments. In the drawings,

Fig. 1 schematically shows the flow diagram of a known from the prior art

Plant for the synthesis of methanol,

Fig. 2 schematically shows the flow diagram of the plant for the synthesis of methanol according to

Figure 1, but with further known from the prior art

specifications,

Fig. 3 schematically shows the flow diagram of a plant for carrying out the proposed method according to a first embodiment,

Fig. 4 schematically shows the flow diagram of a plant for carrying out the proposed method according to a second embodiment,

Fig. 5 schematically shows the flow diagram of a plant for carrying out the proposed method according to a third embodiment,

Fig. 6 schematically shows the flow diagram of a plant for carrying out the proposed method according to a fourth embodiment,

Fig. 7 schematically shows the flow diagram of a plant for carrying out the proposed method according to a fifth embodiment,

June 6, 2023

Fig. 8 schematically shows the flow diagram of a plant for carrying out the proposed process, whereby the external hydrogen is produced on the basis of water electrolysis,

Fig. 9 schematically shows the flow diagram of a plant for carrying out the proposed method according to a further embodiment,

Fig. 10 schematically shows the flow diagram of a plant for carrying out the proposed method according to a further embodiment.

The system shown in Fig. 1, which is known from the prior art, serves the

Synthesis of methanol 1. Unless otherwise stated or explained, the components or processes known from this plant can be transferred to the plant or the process proposed according to the invention. This also applies to the reference symbols used. Those from the prior art

Technology known or equivalent across the embodiments

In order to avoid unnecessary repetition, characteristics are explained only once.

Figure 1 shows the supply of an energy carrier stream 11, formed from e.g. natural gas or biogas and thus containing carbon, into a synthesis gas reactor arrangement 13. In the synthesis gas reactor arrangement 13, a synthesis gas stream 2 comprising hydrogen, carbon monoxide and carbon dioxide is generated from the energy carrier stream 11. The synthesis gas reactor arrangement 13 can have a reforming reactor 30 or an oxidation reactor 31. Assuming the

Synthesis gas reactor arrangement 13 comprises a reforming reactor 30, so in the synthesis gas reactor arrangement 13 an autothermal reforming takes place to

Obtaining the synthesis gas stream 2 takes place. For the autothermal reforming, an oxygen-containing stream 22 is supplied, which was obtained here from an air separation device 23 and essentially comprises oxygen. The

Air separation device 23 is designed to obtain an oxygen stream - in this case the oxygen-containing stream 22 - from the ambient air.

The synthesis gas stream 2 is first fed to a heat recovery device in which the synthesis gas stream 2 is cooled and then

June 6, 2023

In this way, part of the heat generated during the autothermal reforming is recovered. The synthesis gas stream 2 is then fed to a synthesis gas compressor 3 in the plant for further pressure increase.

Subsequently, the synthesis gas stream 2 of the first reactor stage 21a is fed to a methanol reactor arrangement 4, in which first reactor stage 21a a

Methanol synthesis takes place and at least part of the synthesis gas stream 2 in

methanol 1. Unreacted residual gas 16a from the first reactor stage 21a is then fed to a second reactor stage 21b of the methanol reactor arrangement 4 for at least partial conversion into methanol 1. A residual gas stream 15 with unreacted carbon oxides is then obtained from the methanol reactor arrangement 4 and fed to a recycling compressor.

The plant has a pressure swing adsorption system 24 - which is also known as

PSA - designed hydrogen recovery arrangement 5, which recovers a H-recycle stream 7 from a recovery stream 6, which H-recycle stream 7 essentially comprises hydrogen. The

Recovery stream 6 is branched off from unreacted residual gas 16a of the first reactor stage in accordance with the plant concept shown in Figure 1. The remaining gas is also used by the hydrogen recovery arrangement 5 as purge

Stream 8 is output and then burned in a fired heating device of the plant (not shown here). The H-recycle stream 7 is fed to the residual gas stream 15.

As already mentioned, the system has a recycle compressor 14, which

Residual gas stream 15 is compressed. The residual gas stream 15 comprises unreacted residual gas 16b of the second reactor stage 21b, which in turn essentially comprises those components of the synthesis gas which were not converted into methanol 1 in the methanol reactor arrangement 4. Accordingly, the

Residual gas stream 15 contains particularly unreacted carbon oxides. The pressure-increased residual gas stream 15 is initially fed back into the methanol

reactor arrangement 4, namely the first reactor stage.

The unreacted residual gas 16a, b is removed from a first methanol separation device 17a and a second methanol separation device 17b of the methanol reactor system.

06.06.2023 order 4. By condensation, the unreacted LU103148

Residual gas 16a, b on the one hand and a respective first and second crude methanol stream 19a, b on the other hand. The crude methanol streams 19a, b are then subjected to a

Distillation 20 of the plant so that the methanol 1 can be obtained from the raw methanol streams 19a, b. The first methanol separation device 17a is connected downstream of the first reactor stage 21a. The second

The methanol separation device 17b is connected downstream of the second reactor stage 21b.

In the system of Fig. 1, the methanol reactor arrangement 4 - as mentioned - has two reactor stages 21a, b connected in series for the purpose of methanol synthesis. The first reactor stage 21a has two isothermal reactors arranged parallel to one another and the second reactor stage 21b has a single isothermal reactor. The product stream from one reactor stage 21a, b is fed to each of the two methanol separation devices 17a, 17b.

The reactor stage 21a to which the synthesis gas stream 2 is fed directly is referred to as the first reactor stage 21a. The reactor stage 21b is then downstream of this in the sense that the unreacted

Residual gas 16a from the first reactor stage 21a is fed for conversion into methanol 1.

In addition to the unreacted carbon oxides already mentioned, the residual gas stream 15 also contains unreacted hydrogen from the first reactor stage 21a. Any unreacted hydrogen from the residual gas 16a of the first reactor stage 21a is fed to the second reactor stage 21b. Since the hydrogen does not react completely in the second reactor stage 21b either, the unreacted residual gas 16b of the second reactor stage 21b also contains unreacted hydrogen from the first reactor stage 21a.

In the plant according to Fig. 1, a ratio of a first mass flow formed by a sum of carbon-containing compounds present in the purge stream 8 relative to a second mass flow formed by a sum of carbon-containing compounds present in the synthesis gas stream 2 assumes a value of approximately or exactly 0.22.

June 6, 2023

The system shown in Figure 2 comprises all components of the system already described in LU103148

Figure 1 shows the plant. Nevertheless, Figure 2 specifies the type of synthesis gas production based on autothermal reforming in a reforming reactor 30. Before entering the reforming reactor 30, the energy carrier stream 11 is passed through a pre-reforming reactor 29. After adding steam 33, the pre-reformed energy carrier stream 11 enters the

reforming reactor 30. A generated synthesis gas stream 2 then enters a heat recovery device 10.

Figure 3 shows a first embodiment of a system according to the invention. The

Synthesis gas production takes place in a reforming reactor 30 (see the previous explanations for Figure 2). In this example, the reforming reactor 30 thus represents the synthesis gas reactor arrangement 13 or part of the

Synthesis gas reactor arrangement 13 is provided. A hydrogen stream 35 with external hydrogen is supplied to the synthesis gas stream 2 between the heat recovery device 10 and the entry into the synthesis gas compressor 3. The hydrogen stream 35 is heated to 250 ° C by means of a

Hydrogen compressor 45 is pressurized. Furthermore, part of the recovery stream 6 (alternatively from the residual gas 16a) is branched off and fed to the synthesis gas reactor arrangement 13 as a recycle stream 40, namely directly between the pre-reforming reactor 29 and the reforming reactor 30. Alternatively or additionally, a recycle stream can be branched off from a stream 71 downstream of the hydrogen recovery arrangement 5 (here, for example, a pressure swing adsorption device 24), as indicated in dashed lines. The recycle stream 40 is fed to the synthesis gas reactor arrangement 13 as a recycle stream 40, namely directly between

Pre-reforming reactor 29 and reforming reactor 30.

The second embodiment of the proposed system, shown in the

Fig. 4, differs from the embodiment of Fig. 3 in that the

Recovery stream 6 is branched off from the residual gas stream 15 or the residual gas 16b (downstream of the second reactor stage 21b). As in the embodiment according to Fig. 3, the H-recycle stream 7 is fed to the residual gas 16b of the second reactor stage 21b downstream of the first reactor stage 21a. Alternatively, the H-recycle stream 7 can be fed to the synthesis gas stream upstream of the synthesis gas compressor 3. In particular, this feed takes place upstream of the pressure

06.06.2023 increase by the recycle compressor 14. The hydrogen in the H recycle stream 7 corresponding to the unreacted hydrogen from the residual gas 16a of the first reactor stage 21a in the recovery stream 6 thus receives a pressure increase by the recycle compressor 14 with the other unreacted residual gas 16b of the second reactor stage 21b and in particular with unreacted carbon oxides. This pressure increase takes place before this unreacted hydrogen is fed back to the first reactor stage 21a. As already shown in the example according to Figure 3, in this example too - as indicated in dashed lines - a recycle stream 40 can be branched off from a stream 71 downstream of the hydrogen recovery arrangement 5 (here, for example, a pressure swing adsorption device 24). The recycle stream 40 is fed to the synthesis gas reactor arrangement 13 as recycle stream 40, namely directly between the pre-reforming reactor 29 and the reforming reactor 30. As in the example according to Figure 3, a portion of the recovery stream 6 can also be branched off and fed to the synthesis gas reactor arrangement 13 as recycle stream.

The third embodiment of the proposed plant, shown in Fig. 5, differs from the embodiment of Fig. 4 in that the hydrogen recovery arrangement 5 is a membrane arrangement 25. An H recycle stream 7 obtained in the membrane arrangement 25 is added to the hydrogen stream 35 before being fed into the synthesis gas stream 2 via the

Hydrogen compressor 45 and the pressure is increased there. A portion of the recovery stream 6 (here branched off from the residual gas 16b or residual gas stream 15) is fed to the synthesis gas reactor arrangement 13 as a recycle stream 40 after passing through the membrane arrangement 25. This can also be understood as a "branch" from a stream 71 downstream of the hydrogen recovery arrangement 5. A "branch" does not necessarily mean a branch in the pipeline, but can also be referred to as a "feed to" or "line to" (e.g.

B. to the synthesis gas reactor arrangement 13). The supply takes place upstream of the reforming reactor 30. A purge stream 8 is branched off from the recycle stream 40 and burned off. In this embodiment, the H recycle stream 7 is not returned to the residual gas 16b or.

Residual gas stream 15, but via the hydrogen compressor 45 back into the

synthesis loop.

June 6, 2023

The fourth embodiment of the proposed system, shown in Fig. LU103148 6, differs from the embodiment according to Fig. 5 in that the

Purge stream 8 is not branched off from the recycle stream 40 (Fig. 5), but directly from the recovery stream 6. The stream 71 downstream of the hydrogen recovery arrangement 5 is, in this example, directly returned as recycle stream 40 to the synthesis gas reactor arrangement 13 or upstream of the reforming reactor 30. A "branch" in the line engineering

There is no direct return in the sense of the terminology used here, but an immediate return can also be understood as a “branch”.

The fifth embodiment of the proposed system, shown in Fig. 7, differs from the previous embodiments by a

Dispensing with a hydrogen recovery arrangement 5 including H recycle stream 7 and recovery stream 6. A recycle stream 40 is branched off from the residual gas stream 15 and fed to the synthesis gas reactor arrangement 13, namely between pre-reforming reactor 29 and reforming reactor 30. A purge stream 8 is branched off from the recovery stream 40 and burned off. In the system according to Fig. 7, a ratio of a first mass flow formed by a sum of carbon-containing compounds present in the purge stream 8 relative to a mass flow formed by a sum of carbon-containing compounds present in the

The second mass flow formed by the carbon-containing compounds present in synthesis gas stream 2 has a value of approximately or exactly 0.0008.

Figure 8 shows a section of a proposed system in which the oxygen-containing stream 22 fed to the reforming reactor 30 is not obtained from an air separation device 23, but from an electrolysis arrangement 60. The oxygen-containing stream 22 can be supplemented with oxygen from another source, e.g. an air separation device 23. This is an electrolysis arrangement 60 for water electrolysis. This produces oxygen (O,) and hydrogen (H,), the oxygen being/can be pressure-increased before the oxygen-containing stream 22 is formed. The hydrogen produced during the electrolysis can also be used, namely by feeding an electrolysis hydrogen stream 50 to the synthesis gas stream 2 as hydrogen stream 35 after the pressure has been increased by the hydrogen compressor 45. Accordingly, the external hydrogen supplied to the synthesis gas stream 2 can originate from the electrolysis arrangement 60. For reasons of clarity

06.06.2023 the plant components and flows shown in Figures 1 to 7 are excluded in the form of a bracket in LU103148 of Figure 8, namely those components and flows between the first reactor stage 21a and the methanol 1 produced. All of the embodiments, features and flows shown in Figures 3 to 7 can be combined with the generation of external hydrogen by an electrolysis arrangement 60 illustrated in Figure 8. This also applies to the use of an oxidation reactor 31 instead of a reforming reactor. In particular, the methanol reactor arrangement 4 in this example can have only a single reactor stage, but also several reactor stages.

In this example, a residual gas stream 15 can be pressure-increased in a recycle compressor 14. After the pressure increase (but also before),

A recycle stream 40 can be branched off from the residual gas stream 15 and returned to the reforming reactor 30. From the residual gas stream 15, a

Purge stream 8 can be branched off and burned. In the example according to Fig. 8, the carbon-containing energy carrier stream 11 can in particular be

Biogas or another CO, rich gas, for example mixed with CO,

Natural gas. It should be mentioned that when biogas is used as a carbon-containing energy source stream 11, the pre-reformer 29 can be omitted, since biogas hardly contains any higher hydrocarbons.

Fig. 9 shows an embodiment of the proposed system, in which

In contrast to the embodiment according to Fig. 7, a synthesis gas compressor 3 is dispensed with. After the pressure has been increased in the recycle compressor 14, a recycle stream 40 is branched off from the residual gas stream 15 and fed to the synthesis gas reactor arrangement 13, namely between the pre-reforming reactor 29 and the reforming reactor 30. In an alternative, the recycle stream can also be branched off before the pressure increase, compressed in a separate compressor and fed to the synthesis gas reactor arrangement 13. From the

A purge stream 8 is branched off from the residual gas stream 15 and burned off. In the system according to Fig. 9, a ratio of a sum of the purge

The ratio of the first mass flow formed by the carbon-containing compounds present in the stream 8 to a second mass flow formed by a sum of the carbon-containing compounds present in the synthesis gas stream 2 has a value of approximately or exactly 0.005.

June 6, 2023

Fig. 10 shows a further embodiment of the proposed plant, where the reforming reactor 30 is designed as a steam reformer. A carbon-containing energy carrier stream 11 is first fed to a preparation stage 71 and then, with the addition of water vapor 72 and CO, the steam

Reformer trained reforming reactor 30. It is only a

Methanol reactor arrangement 4 with a single reactor stage (the first reactor stage 21a) is provided. Accordingly, only a first methanol separation device 17a is provided downstream of the reactor stage 21. From the

A recirculation stream 40 is branched off from the residual gas stream 15 and fed back to the reforming reactor 30. In this embodiment, the carbon-containing energy carrier stream 11 can be the same energy carrier as in the embodiments according to Figs. 1 to 7, but can also be biogas.

In the plant according to Fig. 10, a ratio of a first mass flow formed by a sum of carbon-containing compounds present in the purge stream 8 relative to a second mass flow formed by a sum of carbon-containing compounds present in the synthesis gas stream 2 assumes a value of approximately or exactly 0.015 or even values < 0.015.

Claims (21)

' 06.06.2023 LU103148 Patent claims 1. Process for the synthesis of methanol (1), wherein a carbon-containing energy carrier stream (11) is fed to a synthesis gas reactor arrangement (13) for obtaining a synthesis gas stream (2) with hydrogen and carbon oxides, wherein the synthesis gas stream (2) is at least partially fed to a first reactor stage (21a) of a methanol reactor arrangement (4) for at least partial conversion into methanol (1), wherein optionally unreacted residual gas (16a) from the first reactor stage (21a) is then fed to a second reactor stage (21b) of the methanol reactor arrangement (4) for at least partial conversion into methanol (1), wherein a residual gas stream (15) with unreacted carbon oxides is obtained from the methanol reactor arrangement (4), which residual gas stream (15) is fed to a recycle compressor (14) for increasing the pressure of the residual gas stream (15), wherein the pressure-increased residual gas stream (15) is fed to the methanol reactor arrangement (4) for at least partial conversion into methanol (1), wherein optionally a recovery stream (6) comprising unreacted residual gas (16a, 16b) of the first and/or second reactor stage (21a, 21b) is fed to a hydrogen recovery arrangement (5) for obtaining an H recycle stream (7), which H recycle stream (7) comprises unreacted hydrogen from the unreacted residual gas (16a) of the first reactor stage (21a) and/or from the unreacted residual gas (16b) of the second reactor stage (21b), wherein the unreacted hydrogen of the H recycle stream (7) is fed again to the first reactor stage (21a) for at least partial conversion into methanol (1), characterized in that upstream or downstream of the synthesis gas reactor arrangement one of the streams (2, 6, 7, 11, 15) is supplied with a hydrogen stream (35) containing external hydrogen, and that a portion of the residual gas stream (15), and/or the optional recovery stream (6), and/or a stream (71) downstream of the hydrogen recovery arrangement (5) is branched off and fed to the synthesis gas reactor arrangement (13) as a recycle stream (40). June 6, 2023 2. Process according to claim 1, characterized in that the synthesis gas stream (2) is fed to a synthesis gas compressor (3) for increasing the pressure. 3. Process according to claim 2, characterized in that the synthesis gas stream (2) is fed to a heat recovery device (10) for recovering heat from the synthesis gas stream (2) and then to the synthesis gas compressor (3). 4. The method according to claim 3, characterized in that the hydrogen stream (35) is fed to the synthesis gas stream (2) after it leaves the heat recovery device (10). 5. Method according to one of claims 1 to 4, characterized in that the hydrogen stream (35) is fed to the synthesis gas stream (2) before it is fed into the synthesis gas compressor (3). 6. Method according to one of the preceding claims, characterized in that unreacted hydrogen from the H recycle stream (7) is additionally fed to the hydrogen stream (35). 7. Method according to one of the preceding claims, characterized in that the hydrogen stream (35) is pressure-increased by means of a hydrogen compressor (45) before being fed into the methanol reactor arrangement (4), in particular into the synthesis gas stream (2). 8. The method according to claim 6 and 7, characterized in that the unreacted hydrogen from the H recycle stream (7) is fed to the hydrogen stream (35) via the hydrogen compressor (45), in particular that the unreacted hydrogen and the external hydrogen are jointly pressure-increased by means of the hydrogen compressor (45). 9. Process according to one of the preceding claims, characterized in that the unreacted hydrogen from the H recycle stream (7) is fed to the unreacted residual gas (16b) of the second reactor stage (21b). ’ 06.06.2023 10.Process according to one of the preceding claims, characterized in that the external hydrogen is supplied to the hydrogen stream (35) from an electrolysis hydrogen stream (50) which is obtained from an electrolysis arrangement (60) for decomposing water into the external hydrogen and oxygen. 11.Process according to one of the preceding claims, characterized in that the methanol reactor arrangement (4) comprises a first methanol separation device (17a) for obtaining the unreacted residual gas (16a) of the first reactor stage (21a) and a first crude methanol stream (19a) of the first reactor stage (21a), in particular that the first methanol separation device (17) comprises a first condensation device (18a) for obtaining the unreacted residual gas (16a) of the first reactor stage (21a) and the first crude methanol stream (19a) of the first reactor stage (21a) by condensation, and optionally further characterized in that the methanol reactor arrangement (4) comprises a second methanol separation device (17b) for obtaining the unreacted residual gas (16b) of the second reactor stage (21b) and a second crude methanol stream (19b) of the second reactor stage (21b), in particular that the second methanol separation device (17b) comprises a second condensation device (18b) for recovering the unreacted residual gas (16b) of the second reactor stage (21b) and the second crude methanol stream (19b) of the second reactor stage (21b) by condensation. 12.Process according to one of the preceding claims, characterized in that the second reactor stage (21b) is arranged downstream of the first reactor stage (21a) in terms of process technology, wherein the recycle compressor (14) is preferably arranged between the two reactor stages (21a, b) in terms of process technology. 13.Process according to one of the preceding claims, characterized in that the residual gas stream (15) is obtained from the second reactor stage (21b), in particular that the recycle compressor (14) supplies the pressure-increased residual gas stream (15) to the first reactor stage (21a). June 6, 2023 14.Process according to one of the preceding claims, characterized in that the synthesis gas reactor arrangement (13) comprises a reforming reactor (30) or an oxidation reactor (31). 15. Method according to one of the preceding claims, characterized in that an oxygen-containing stream (22) is fed to the synthesis gas reactor arrangement (13), the oxygen comprised in the oxygen-containing stream (22) being obtained from an air separation device (23) for obtaining oxygen from ambient air, and/or the oxygen comprised in the oxygen-containing stream (22) being obtained from the electrolysis arrangement (60). 16.Process according to one of the preceding claims, characterized in that the recycle stream (40) of the synthesis gas reactor arrangement (13) is fed upstream of the reforming reactor (30) or the oxidation reactor (31). 17.Process according to one of the preceding claims, in that a pre-reforming reactor (29) is arranged upstream of the reforming reactor (30), wherein the recycle stream (40) is fed to the synthesis gas reactor arrangement (13) between the pre-reforming reactor (29) and the reforming reactor (30). 18.Process according to one of the preceding claims, characterized in that the hydrogen recovery arrangement (5) has a pressure swing adsorption device (24) or a membrane arrangement (25) for obtaining the H recycle stream (7) from the recovery stream (6). 19.Process according to one of the preceding claims, characterized in that the hydrogen recovery arrangement (5) outputs a purge stream (8), and/or that a purge stream (8) is branched off from the recycle stream (40), and/or that a purge stream (8) is branched off from the recovery stream (6), and/or that a purge stream (8) is branched off from the residual gas stream (15), wherein the purge stream is preferably fed to a combustion facility or fed to a flare. ) 06.06.2023 20.Process according to one of the preceding claims, characterized in that a ratio of a molar mass flow of carbon-containing compounds in the purge stream (8) relative to the synthesis gas stream (2) assumes a value of 10-° to 0.4, and preferably assumes a value of 0.0001 to 0.3, and more preferably assumes a value of 0.0005 to 0.21. 21.Plant for the synthesis of methanol (1) with a synthesis gas reactor arrangement (13) for obtaining a synthesis gas stream (2) with hydrogen and carbon oxides from a carbon-containing energy carrier stream (11) fed to the synthesis gas reactor arrangement (13), with a methanol reactor arrangement (4) which has a first reactor stage (21a) and optionally a second reactor stage (21b), with a recycle compressor (14), and optionally with a hydrogen recovery arrangement (5), a device for at least partially feeding the synthesis gas stream (2) into the first reactor stage (21a) for at least partial conversion into methanol (1), an optional device for feeding unreacted residual gas (16a) from the first reactor stage (21a) to the optional second reactor stage (21b) for at least partial conversion into methanol (1), with a device for obtaining a residual gas stream (15) from the methanol reactor arrangement (4) with unreacted carbon oxides, with a device for feeding the residual gas stream (15) into the recycle compressor (14) to increase the pressure of the residual gas stream (15), with a device for feeding the pressure-increased residual gas stream (15) into the methanol reactor arrangement (4) for at least partial conversion into methanol (1), with an optional device for feeding a recovery stream (6) comprising unreacted residual gas (16a, 16b) of the first and/or second reactor stage (21a, 21b) into the hydrogen recovery arrangement (5) to obtain a H recycle stream (7), wherein the H recycle stream (7) contains unreacted hydrogen from the unreacted residual gas (16a) of the first reactor stage (21a) and/or from the unreacted residual gas (16b) of the second reactor stage (21b), with a device for re-feeding the unreacted hydrogen of the H recycle stream (7) into the first reactor stage (21a) for at least partial conversion into methanol (1), characterized by a device for feeding a hydrogen stream (35) with external hydrogen to one of the streams (2, 6, 7, 11, ° 06.06.2023 15) upstream or downstream of the synthesis gas reactor arrangement, one or LU103148 several devices for branching off and feeding a portion of the residual gas stream (15), and/or the optional recovery stream (6), and/or a stream (71) downstream of the hydrogen recovery arrangement (5) into the synthesis gas reactor arrangement (13) as a recycle stream (40).