DE102012020470A1 - Method for separating methane from synthesis gas that is utilized for e.g. combustion in power plant, involves utilizing liquefied methane-rich fraction process for cooling and vaporizing synthesis gas in heat exchangers - Google Patents

Abstract

The method involves cooling a methane-containing synthesis gas (SYN) in two heat exchangers (E1, E2), and obtaining methane (MET) as a gaseous product from the cooled synthesis gas in a liquefied methane-rich fraction process. The liquefied methane-rich fraction process is utilized in the heat exchangers for cooling and vaporizing the synthesis gas. A refrigerant i.e. dry nitrogen, from a refrigerant circuit is compressed using a circuit compressor. The compressed refrigerant is relaxed and fed into the heat exchangers for cooling of the synthesis gas in the heat exchangers. An independent claim is also included for a device for separating methane from a methane-containing synthesis gas.

Description

The present invention relates to a method for the separation of methane from a methanhaltrgen synthesis gas and a corresponding device.

State of the art

Synthesis gases, which are produced by known methods from coal, oil or natural gas, usually after removal of sour gas in addition to the desired components hydrogen and carbon monoxide and methane still with a typical proportion of 3 to 30 vol.% And smaller amounts of other components , These are, for example, each less than 1 vol.% Nitrogen, oxygen, argon, carbon dioxide and ethane. In particular, since methane is undesirable in the synthesis gas, it is usually separated.

The separation of methane from methane-containing synthesis gas can be carried out in a cryogenic separation plant. This can be operated with a refrigeration cycle in which a refrigerant, for example, multi-stage and under intermediate and aftercooling, is compressed. The compressed refrigerant may then be cooled in one or more heat exchangers. The compressed and cooled refrigerant is relieved cold and thus covers the refrigeration demand of the system.

A method and system for separating methane from methane-containing synthesis gas is for example US 2009/0205367 A1 known.

The refrigeration demand in such cryogenic separation plants, in particular for the cooling of the synthesis gas, is considerable. The required cooling capacity is introduced into the system mainly in the form of compressor capacity. The energy requirement is high. The compressor systems are expensive and expensive to create and maintain due to the required performance.

The invention is therefore based on the object to show more efficient ways to methane separation from a methane-containing synthesis gas.

Disclosure of the invention

Against this background, the present invention proposes a method for the separation of methane from a methane-containing synthesis gas and a corresponding device with the features of the independent claims. Preferred embodiments are the subject of the respective dependent claims and the following description.

In the present application, substances and mixtures of substances in a plant or a process, for example, synthesis gas and refrigerants, referred to as "streams" and "fractions". A stream is usually routed as fluid in a conduit designed for this purpose. A fraction usually denotes a portion of a starting mixture separated from a starting mixture. A political group can generate a corresponding current at any time if it is managed accordingly. Conversely, for example, a stream can serve to provide a starting mixture from which a fraction can be separated.

A stream or fraction may be "rich" or "poor" in one or more of its contained components, with "rich" accounting for greater than 75%, 80%, 85%, 90%, 95%, 99%, 99.5% or 99.9% and "poor" for less than 25%, 20%, 15%, 10%, 5%, 1%, 0.5% or 0.1%, respectively a weight or volume basis, can stand.

Advantages of the invention

The invention can be used, for example, in a process for the separation of methane from a methane-containing synthesis gas, in which the synthesis gas is first cooled in at least one heat exchanger and the methane is first recovered from the cooled synthesis gas in a liquefied methane-rich fraction. According to the invention, however, it is now provided to use the liquefied methane-rich fraction at least partially in the at least one heat exchanger for the cooling of the synthesis gas and in this case to evaporate.

A usable for this purpose cryogenic separation plant was developed by the applicant and is the subject of a parallel patent application. She is partly in the 1 illustrated and is explained in more detail in the figure description.

The methane-containing synthesis gas can be cooled in such a cryogenic separation plant, as mentioned, first by heat exchange. From the cooled methane-containing synthesis gas, a methane-rich and carbon monoxide-containing bottom fraction is cryogenically separated in a first separation column. The methane-rich and carbon monoxide-containing bottoms fraction is transferred to a second separation column in which the carbon monoxide is largely desorbed (stripped off) from the bottom fraction. Among other things, a low-carbon methane fraction and a carbon monoxide-rich overhead stream are obtained. The latter can be recycled as reflux into the first separation column. The low-carbon methane fraction is initially liquid and is conventionally supercooled and taken from the plant in liquid form as a corresponding product. According to the invention, however, this liquid low-carbon methane fraction is used as a refrigerant for cooling the methane-containing synthesis gas.

The cryogenic separation plant comprises a refrigerant circuit with a refrigerant, for example nitrogen. In this, the refrigerant is compressed, for example, multi-stage and intermediate and after-cooling of a low outlet pressure to a high final pressure. The compressed refrigerant is then cooled by heat exchange and then released cold performance. Here, for example, expander and / or expansion valves can be used, wherein the refrigerant can be divided at different temperature levels into several refrigerant streams and can be relaxed separately. A relaxed refrigerant stream can be fed inter alia in a top condenser of the second separation column. After the expansion, the refrigerant is preferably present with a high liquid content, for example as a two-phase stream or completely liquefied.

The present invention makes use of to reduce the energy required to meet the refrigeration demand that with the liquefied methane-rich fraction a suitable refrigerant for cooling is available, from which the previously introduced cooling capacity can be recovered. The invention can be used whenever the separated methane is required as a gaseous product, for example for combustion in a power plant, a feed into a pipeline or as a feedstock for chemical plants.

The proposed measures make it possible, as explained in more detail below, to save compressor performance because at least part of the cooling required for the cooling of the synthesis gas is covered by the liquefied methane-rich fraction. In the conventional systems can thus be saved at least one expander and the expander with the usually coupled Nachverdichter. However, a still-existing expander that may be coupled to a corresponding compressor may still be used to adjust a purity of a recovered synthesis gas product.

The refrigeration cycle of the system can work largely with gaseous refrigerant due to the lower amount of refrigerant required, so that results in a simplified wiring. At the same time, pressure losses are reduced and there are no part-load problems due to entrainment as in conventional systems in which corresponding lines lead two-phase refrigerant.

The invention therefore makes possible a cost-effective separation of methane from synthesis gas which can be realized with minimal mechanical and energy expenditure.

Advantageously, the invention is thus employed in a known process in which a methane-rich and carbon monoxide-containing bottom fraction is separated from the cooled synthesis gas in a first separation column and at least partially desorbed from the bottom fraction in a second separation column to obtain the liquefied, methane-rich fraction carbon monoxide. The invention is used in particular in two-column processes in which the columns are operated at different pressures.

However, it can be used in all processes in which a liquid fraction is separated cryogenically and can then be heated in heat exchange. The method is particularly suitable for methane-containing synthesis gases with hydrogen and carbon monoxide levels of 10 to 95%, for example, for synthesis gases obtained by the coal gasification.

In the method advantageously two heat exchangers are used, wherein the synthesis gas is first cooled in a first and then in a second of the two heat exchangers and the liquefied methane-rich fraction is passed in countercurrent first through the second and then through the first heat exchanger. As explained below, the synthesis gas between the cooling in the first and the second heat exchanger can also be cooled in further heat exchangers.

With particular advantage, the synthesis gas in the first heat exchanger to a temperature of -60 to -110 ° C, especially -80 to -95 ° C and in the second heat exchanger to a temperature of -120 to -170 ° C, in particular - 130 to -160 ° C, cooled. The temperature from -60 to -110 ° C is particularly suitable for subsequent use in another heat exchanger, for example a bottom reboiler or side evaporator of a second separation column. The lower temperature of -120 to -170 ° C leads to a liquefaction of the methane contained in the synthesis gas.

In the method described, for the cooling of the synthesis gas in the at least one heat exchanger advantageously also a refrigerant from a refrigerant circuit is used, wherein the refrigerant in the refrigerant circuit is first compressed, then relaxed, and then fed into the at least one heat exchanger. As explained, this can be used to specifically cover the cooling requirements of the system. Due to the However, according to the invention utilization of the cold of the liquefied methane-rich fraction reduces the equipment and energy costs for the operation of the refrigerant circuit considerably.

Advantageously, the refrigerant circuit for compressing and decompressing the refrigerant comprises at least one expander mechanically coupled to a compressor. This can be advantageously used to produce peak cold, thereby increasing the purity of a recovered synthesis gas product, i. H. whose residual methane content can be specifically controlled.

In the method, at least one cycle compressor can advantageously be used for compressing the refrigerant in the refrigerant circuit. This may be a common cycle compressor, as used in conventional air separation plants. On more complex compressor systems can be omitted. The correspondingly created systems are thus far more cost-effective.

As explained, the method according to the invention can always be used if at least part of the previously liquefied methane-rich fraction used in the at least one heat exchanger for cooling the synthesis gas and vaporized is discharged as gaseous methane product. In a corresponding system, however, a liquid, for example supercooled, methane product can additionally be dispensed.

A corresponding method advantageously comprises the use of at least one further heat exchanger in which a fluid removed at a defined removal height of the second separation column is heated. In this case, such a further heat exchanger can be designed, for example, as a so-called bottom reboiler, in which bottom reboiler a fluid withdrawn from the bottom of the second separation column can be heated and optionally evaporated. Furthermore, such a further heat exchanger may be provided in the form of a side evaporator. In this, a withdrawn, for example, in a separating bottom fluid heated and optionally evaporated. By using appropriate heat exchangers, the separation efficiency increases in the second separation column.

For heating the fluid removed in the at least one defined removal height of the second separation column in the at least one heat exchanger, for example in a bottom reboiler, at least the methane-containing synthesis gas cooled in the first heat exchanger is used according to an advantageous embodiment. This further reduces the energy required to cool the methane-containing synthesis gas. Alternatively or additionally, it may also be advantageous to use at least a portion of a refrigerant from the refrigerant circuit for heating the fluid removed in the at least one defined removal height of the second separation column, for example in a bottom reboiler.

It may also be advantageous to heat at least a portion of the carbon monoxide-containing bottoms fraction deposited in the first separation column in such a process in the second heat exchanger. As a result, it is possible to dispense with an otherwise required further heat exchanger (bottom reboiler and / or side evaporator).

The device according to the invention is set up for carrying out the method explained for the separation of methane from a methane-containing synthesis gas and has corresponding means. It benefits from the advantages explained above in the same way so that reference can be made to them.

The device is designed as a cryogenic separation plant and has at least one heat exchanger which is adapted to cool the synthesis gas and at least one device which is adapted to recover the methane from the cooled synthesis gas in a liquefied methane-rich fraction on. Means are also provided which are adapted to at least partially use the liquefied methane-rich fraction in the at least one heat exchanger for the cooling of the synthesis gas.

The invention will be further elucidated with reference to the accompanying figures which show inter alia preferred embodiments of the invention.

Brief description of the drawings

1 shows a plant for the separation of methane from a methane-containing synthesis gas according to the prior art in a schematic representation.

2 shows a plant for the separation of methane from a methane-containing synthesis gas according to an embodiment of the invention in a schematic representation.

3 shows a plant for the separation of methane from a methane-containing synthesis gas according to an embodiment of the invention in a schematic representation.

4 shows a plant for the separation of methane from a methane-containing synthesis gas according to an embodiment of the invention in a schematic representation.

In the figures, the same or corresponding elements are provided with identical reference numerals. The in terms of the 1 The statements made in terms of pressures, temperatures, compositions and the like also apply to those in the 2 to 4 illustrated embodiments of the invention, unless otherwise specified therein.

Detailed description of the drawings

1 shows a system not according to the invention for the separation of methane from a methane-containing synthesis gas. The plant is in total with 100 designated.

The attachment 100 has a first separation column S1 and a second separation column S2. The first separation column S1 and the second separation column S2 are operated at different pressures. The pressure difference is for example 5 to 30 bar, in particular 10 to 20 bar. The pressure of the second separation column S2, in order to ensure a density difference between gas and liquid phase of at least 240 kg / m ³ , in particular at least 270 kg / m ³ , be limited to 25 to 30 bar.

A methane-containing synthesis gas SYN is in a first heat exchanger E1 to a temperature of for example -60 to -110 ° C, in particular -80 to -95 ° C, and in a second heat exchanger E2 to a temperature of for example -120 to -170 ° C. , in particular -130 to -160 ° C, cooled and fed to the first separation column S1 in a defined feed height. In the first separation column S1, methane can be washed out of the methane-containing synthesis gas SYN by means of a carbon monoxide-rich reflux pumped by a pump L1. In this way a low-methane head fraction and a methane-rich and carbon monoxide-containing bottom fraction are obtained.

The carbon monoxide-containing bottoms fraction is deposited at the bottom of the first separation column S1. The low-methane overhead fraction is withdrawn from the top of the first separation column S1, heated in the heat exchangers E2 and E1 and depleted to a residual methane content of, for example, 0.01 to 1.00 vol.%, In particular 0.1 to 0.5 vol.% Synthesis gas product PRO delivered.

The methane-rich and carbon monoxide-containing bottoms fraction from the first separation column S1 is expanded via a valve V3 to the pressure of the second separation column S2 and, again in a defined feed height, fed into the same. The second separation column S2 is operated as a so-called carbon monoxide stripper. Here, a third and a fourth heat exchangers E3 and E4 are provided, which are operated as a bottom reboiler (third heat exchanger E3) on the one hand and as a side evaporator (fourth heat exchanger E4) on the other hand and heated with a refrigerant. The second separation column S2 also has a condenser E5, which is designed, for example, as a top condenser and in which vapors ascending in the second separation column S2 can be condensed out.

In the bottom of the second separation column S2, a low-carbon methane fraction having a concentration of, for example, 0.01 to 1.00 vol.%, In particular 0.1 to 0.5 vol.% Carbon monoxide - the liquefied methane-rich fraction - can be obtained. This can be performed for example by the heat exchanger E2. It can be delivered in the form of a methane product LNG either as a boiling or supercooled liquid.

A gaseous overhead fraction of the second separation column S2 is recompressed in a recompressor C4 to the pressure of the first separation column S1 and admixed with the feed stream SYN to the first separation column S1.

A liquid, carbon monoxide-rich overhead stream is withdrawn from the top bottom of the second separation column S2, pumped in the mentioned pump L1 to the pressure of the first separation column S1 and fed to the first separation column S1 as a carbon monoxide-rich reflux. This is used to wash out the methane in the first separation column S1.

For cooling or heating the second separation column S2, d. H. for the operation of the third heat exchanger E3, the fourth heat exchanger E4 and the condenser E5, a preferably closed refrigerant circuit is provided.

This comprises a preferably multi-stage main compressor C1 with intermediate coolers E6, E7 and E8 and a first and a second booster C2 and C3 with an aftercooler E9. In the main compressor C1 and the secondary compressors C2 and C3, a gaseous refrigerant, such as technically pure, dry nitrogen, from an initial pressure PA of, for example, 5 to 20 bar, in particular 8 to 15 bar via corresponding intermediate pressures to a final pressure PE, for example 50 to 100 bar, in particular 60 to 90 bar, are compressed. The outlet pressure PA is according to the definition made here suction side of the main compressor C1, the final pressure PE pressure side of the post-compressor C3, as illustrated by dashed lines shown in the figure.

The first after-compressor C2 and the second after-compressor C3 can each be driven via expander X2 and X1, which are also operated with the refrigerant. The refrigerant is expanded in the expander X2 and X1 each working and cold-performing, the freeing cold respectively for the operation of the first and second heat exchangers E1 and E2 and the released mechanical power to operate the first and second booster C2 and C3 is used. The expanders X1 and X2 are referred to hereinafter as "warm" and "cold" expanders X2 and X1, respectively, according to the temperatures of the optionally expanded refrigerant therein, the warm expander X2 being the first after-compressor C2 and the first expander the second after-compressor C3 is assigned.

The "warm" portion of the refrigerant can be relaxed in the warm expander X2 to a pressure of for example 5 to 20 bar, in particular 8 to 15 bar, cold and work. The expanded refrigerant stream can then be further warmed in the first heat exchanger E1 and then fed to the main compressor C1 again.

Subsequently, a proportion of the refrigerant, for example, 50 to 97%, diverted and, as explained above, be performed by the third and the fourth heat exchanger E3 and E4. This is done, as mentioned, a corresponding cooling. After reconnecting with a residue not passed through the third and fourth heat exchangers E3 and E4, the refrigerant has an intermediate temperature TI resulting from the cooling in the first heat exchanger E1 on the one hand and the partial further cooling in the heat exchangers E3 and E4 on the other results. As explained, the refrigerant in the first heat exchanger E1 is at a temperature of, for example, -60 to -120 ° C; especially -90 to -110 ° C, cooled. In the third and the fourth heat exchangers E3 and E4, a further cooling of a correspondingly branched portion to a temperature of, for example, -80 to -130 ° C, in particular -100 to -120 ° C. Thus, the intermediate temperature TI between these temperatures, but in any case higher than the final temperature TE, which is achieved in the second heat exchanger with, for example, -140 to -180 ° C, especially -150 to -170 ° C.

The refrigerant with the intermediate temperature TI is now again divided into a first and a second portion. A first portion, for example 60 to 95% of the refrigerant, is supplied to the cold expander X1. The intermediate temperature TI of the refrigerant supplied to the cold expander X1 is adjusted so that no liquefaction takes place in the expander X1. The released by the relaxation of cold is used for cooling in the second heat exchanger E2, with a released mechanical power of the booster C3 is driven.

By contrast, the second portion, ie the remainder, is then cooled directly from said intermediate temperature TI to the end temperature TE explained several times, as mentioned, for example, -140 to -180 ° C., in particular -150 to -170 ° C. Via a relaxation valve V1, this second portion of the refrigerant is expanded to a feed pressure PC and fed into the condenser E5. As a result, the refrigerant is partially or completely liquefied.

In other words, the demand for liquid refrigerant for the condenser C5 is covered by the expansion valve V1 and a refrigerant having the final temperature TE. The cold expander X1, on the other hand, is supplied with a refrigerant having a higher temperature TI, so that the refrigerant in the expander X1 does not liquefy. However, the released cooling and working power can still be used to operate the second heat exchanger E2 and the post-compressor C3.

The invention can also be used in plants with a different configuration. Thus, for example, the expander X1, a cooled to a much lower temperature refrigerant can be supplied, so that there is a two-phase mixture after the relaxation.

In the condenser E5 at least a portion of the liquid fraction is evaporated. Subsequently, the refrigerant, which may now have a liquid content of, for example, 0 to 20%, in particular 0 to 10%, on the one hand via a liquid line with a valve V4 and on the other hand via a gas line separated from the head of the condenser E5 and with the in the cold expander X1 vaporized first portion of the refrigerant to be united.

The refrigerant is then combined with the first portion and in the heat exchangers E2 and E1, if necessary, completely evaporated and optionally superheated, and then fed back to the main compressor C1.

In 2 is a plant for the separation of methane from a methane-containing synthesis gas according to an embodiment of the invention shown schematically and in total with 10 designated. The attachment 10 has the essential components of the above-mentioned plant 100 on.

Also in the plant 10 In the bottom of the second separation column S2, a low-carbon methane fraction having a concentration of, for example, 0.01 to 1.00% by volume, in particular 0.1 to 0.5% by volume, of carbon monoxide is obtained. This methane-rich liquefied fraction is in contrast to the plant 100 However, in the heat exchanger E2 and then the heat exchanger E1 each cold side supplied and heated and evaporated in this, so that the methane-rich liquefied fraction can be vaporized and discharged as a gaseous methane product MET at any pressure. For example, a pressure in the range of 1 to 100 bar is selected. A division of the methane product MET into several parallel product streams with different release states, such. As liquid, boiling, supercooled and / or gaseous, is also possible.

By using the methane-rich liquefied fraction as the refrigerant in the first and the second heat exchangers E1 and E2, the warm expander X2, and thus the compressor C2 coupled thereto, which is in 1 is shown waived. However, a booster expander assembly including the booster C3 and the expander X1 may still be provided to provide the peak cooling required to adjust the purity of the syngas product.

In 3 is a plant for the separation of methane from a methane-containing synthesis gas according to an embodiment of the invention shown schematically and in total with 11 designated. The attachment 11 has up to the fourth heat exchanger E4, the essential components of the previously described system 100 on.

Instead of using a fourth heat exchanger E4 designed as a side evaporator, it is provided to lead a portion of the bottom-side separated in the first separation column S1 rich methane and carbon monoxide sump fraction via a pressure relief valve V5 and to heat in the second heat exchanger E2. The fraction of the bottoms fraction which has been decompressed via the expansion valve V5 and heated in the second heat exchanger E2 is then fed into the second separation column S2 at a defined feed height, whereby heating takes place here. In this way, the function of the fourth heat exchanger E4 can be realized with less equipment expense, which saves costs.

In the plant 11 the intermediate temperature TI of the refrigerant thus results from the cooling in the first heat exchanger E1 and the further cooling of a corresponding proportion in the third heat exchanger E3.

Another plant for the separation of methane from a methane-containing synthesis gas according to an embodiment of the invention is in 4 shown schematically and in total with 12 designated. The attachment 12 has the essential components of the above-mentioned plant 11 on.

In the plant 12 However, the third heat exchanger operated as a bottom reboiler is not supplied with a refrigerant from the refrigerant circuit, but with at least a partial flow of the cooled in the first heat exchanger E1 methane-containing synthesis gas SYN. This is therefore performed here first via the first heat exchanger E1, then via the third heat exchanger E3 and then via the second heat exchanger E2. The attachment 12 This can be operated even more efficiently.

In the plant 12 The intermediate temperature TI of the refrigerant thus essentially results only from the cooling in the first heat exchanger E1.

A further advantageous embodiment of the method, which is not shown in the figures, however, relates to the heat exchangers E1 and / or E2. Advantageously, separate heat exchangers for methane / LNG, methane-containing synthesis gas SYN and / or the product stream PRO on the one hand and the refrigerant streams on the other can also be provided here. This allows a more cost-effective implementation. This applies in particular to the heat exchanger E1, but may also be advantageous with respect to the heat exchanger E2. The illustrated heat exchangers E1 and / or E2 can therefore also be realized in the form of two or more structural units.

With the present invention, plants can be operated in which a methane-containing synthesis gas SYN between an entry into and an exit from the overall process, here defined respectively as inlet and outlet into and out of the first heat exchanger E1, only a pressure difference , in particular a pressure drop, in the range of 1 to 3 bar, for example from 1.5 to 2.5 bar, is subjected.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2009/0205367 A1 [0004]

Claims (14)

Process for the separation of methane (MET) from a methane-containing synthesis gas (SYN), in which the synthesis gas (SYN) is first cooled in at least one heat exchanger (E1, E2) and the methane (MET) from the cooled synthesis gas (SYN) in a liquefied one methane-rich fraction is recovered, characterized in that is used, the liquefied methane-rich fraction is at least partially in the at least one heat exchanger (E1, E2) to the cooling of the synthesis gas (SYN) and thereby evaporated. Process according to claim 1, wherein a methane-rich and carbon monoxide-containing bottoms fraction is separated from the cooled synthesis gas (SYN) in a first separation column (S2) and at least partially desorbed from the bottom fraction in a second separation column to obtain the liquefied, methane-rich fraction carbon monoxide , Method according to claim 1 or 2, in which two heat exchangers (E1, E2) are used, wherein the synthesis gas (SYN) is cooled first in a first (E1) and then in a second (E2) of the two heat exchangers and the liquefied methane-rich fraction in the Counterflow initially through the second (E2) and then passed through the first (E1) heat exchanger and thereby evaporated. The method of claim 3, wherein the synthesis gas (SYN) in the first heat exchanger (E1) to a temperature of -60 to -110 ° C, in particular -80 to -95 ° C and in the second heat exchanger (E2) to a temperature from -120 to -170 ° C, especially -130 to -160 ° C, is cooled. Method according to one of the preceding claims, in which for the cooling of the synthesis gas (SYN) in the at least one heat exchanger (E1, E2) further comprises a refrigerant from a refrigerant circuit is used, wherein the refrigerant in the refrigerant circuit first compressed, then relaxed and then in the at least one heat exchanger (E1, E2) is fed. Method according to Claim 5, in which at least one expander (X1) mechanically coupled to a compressor (C3) is used for compressing and depressurizing the refrigerant in the refrigerant circuit. A method according to claim 5 or 6, wherein at least one cycle compressor is used for compressing the refrigerant in the refrigerant circuit. Method according to one of claims 5 to 7, wherein technically dry nitrogen is used as the refrigerant. Method according to one of claims 5 to 8, wherein a partial flow of the refrigerant is expanded in the at least one expander (X1), wherein the cold generated by the at least one expander (X1) is used to supply the second heat exchanger (E2), and wherein a further partial flow of the refrigerant in the second heat exchanger (E2) further cooled and then to provide cold for a heat exchanger (E5) of a top condenser of the second separation column (S2) is relaxed. Method according to one of the preceding claims, in which at least part of the previously liquefied methane-rich fraction used and evaporated in the at least one heat exchanger (E1, E2) for the cooling of the synthesis gas (SYN) is discharged as gaseous methane product (MET) , Method according to one of claims 2 to 10, wherein at least one further heat exchanger (E3, E4) is used, in which a in a defined removal height of the second separation column (S2) removed fluid is heated. The method of claim 11, wherein in the at least one further heat exchanger, at least a portion of the synthesis gas (SYN) is cooled. Method according to one of claims 3 to 12, wherein in the second heat exchanger (E2) at least a portion of the deposited in the first separation column carbon monoxide-containing bottom fraction is heated. Contraption ( 10 . 11 . 12 ) arranged to carry out a process for the separation of methane (LNG) from a methane-containing synthesis gas (SYN) according to any one of the preceding claims and as a cryogenic separation plant ( 10 ) is formed, with at least one heat exchanger (E1, E2), which is adapted to cool the synthesis gas (SYN), and at least one device which is adapted to the methane (MET) from the cooled synthesis gas (SYN) in a liquefied methane-rich fraction, further comprising means adapted to use the liquefied methane-rich fraction at least partially in the at least one heat exchanger (E1, E2) for the cooling of the synthesis gas (SYN).

Images