EP2997320A2

EP2997320A2 - Installation for reducing a carbon dioxide content of a gas flow which contains carbon dioxide and is rich in hydrocarbons, and a corresponding method

Info

Publication number: EP2997320A2
Application number: EP14879279.9A
Authority: EP
Inventors: Robert Adler; Sascha Dorner; Ekkehardt Klein; Christoph Nagl
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2013-05-16
Filing date: 2014-05-08
Publication date: 2016-03-23
Also published as: DE102013008535A1; WO2015154786A3; WO2015154786A2

Abstract

The invention relates to an installation (1) configured to reduce a carbon dioxide content of a gas flow (A) that contains carbon dioxide and is rich in hydrocarbons, comprising a first and a second segregating unit (10, 20) each of which has a cryogenic condenser (11, 21) that is arranged in a segregation chamber (12, 22) and can be supplied with a coolant (C), and means (30, 40) being provided that are configured, in a first operating mode, to guide the coolant (C) through the cryogenic condenser (11) of only the first segregating unit (10) and to guide the carbon dioxide-containing, hydrocarbon-rich gas flow (A) through the segregation chamber (12) of only the first segregating unit (10), and to heat the second segregating unit (20) and remove a carbon dioxide-rich flow (D) from said second segregating unit (20); and being configured, in a second operating mode, to guide the coolant (C) through the cryogenic condenser (21) of only the second segregating unit (20) and to guide the carbon dioxide-containing, hydrocarbon-rich gas flow (A) through the segregation chamber (22) of only the second segregating unit (20), and to heat the first segregating unit (10) and remove a carbon dioxide-rich flow (D) therefrom. The invention also relates to a corresponding method.

Description

description

Plant for reducing a carbon dioxide content of a carbon dioxide-containing and hydrocarbon-rich gas stream and corresponding method

The invention relates to a system for reducing a carbon dioxide content of a carbon dioxide-containing and hydrocarbon-rich gas stream and a

corresponding procedure.

PRIOR ART Typical natural gases are gas mixtures whose chemical

Composition may vary considerably depending on the deposit. In addition to the main constituent methane (between 75% and 99% on a molar basis), natural gas often also contains higher levels of ethane (between 1% and 15%), propane (between 1% and 10%), butane and ethene. Other ingredients include hydrogen sulphide (between 0% and 35%), nitrogen (between 0% and 15%, in extreme cases up to 70%), carbon dioxide (between 0% and 10%) and water.

Hydrogen sulphide, carbon dioxide and water must be separated from the natural gas because they are either toxic, can attack the pipelines used or form solid deposits by hydrate formation. Carbon dioxide and water can also freeze out during natural gas liquefaction.

Other hydrocarbon-rich gas mixtures such as biogas, sewage gas and

Landfill gas i.d.R. a high carbon dioxide content (between 25% and 55%). This, too, must be at least reduced before use.

To reduce the carbon dioxide content of carbon dioxide-containing gas streams, different methods are known from the prior art. For example, so-called gas scrubbing can be used to reduce the carbon dioxide content of exhaust gases, as disclosed in DE10 2009 017 228 A1. After such gas scrubbing, however, possibly too high carbon dioxide contents remain. Adsorptive processes for reducing the carbon dioxide content, for example with adsorption on zeolites as disclosed in EP 2 158 020 A1, also have disadvantages. In particular, the regeneration of the adsorbent at relatively high temperatures between 120 and 250 ° C must take place. Due to the temperature change, the adsorbent is heavily stressed and its life reduced. The removal of carbon dioxide by membrane or pressure swing adsorption also has disadvantages, in particular because specific pressures must be maintained here.

There is therefore a need for improved ways of reducing the carbon dioxide content of carbon dioxide-rich and hydrocarbon-rich

Gas flows, in particular of natural gas and non-fossil gas mixtures.

DISCLOSURE OF THE INVENTION This object is achieved by a system for reducing a carbon dioxide content of a carbon dioxide-containing and hydrocarbon-rich gas stream and a corresponding method having the features of the independent patent claims. Preferred embodiments are each the subject of the dependent

Claims and the following description.

Advantages of the invention

The invention proposes a plant adapted to reduce a carbon dioxide content of a carbon dioxide-rich and hydrocarbon-rich gas stream. The system according to the invention has a first and a second separation unit. In each case, the first and the second separation unit comprise a cryocapacitor arranged in a separation space and furthermore each with a particularly cryogenic refrigerant. In the context of this application, a "separation unit" is understood to mean an apparatus through which a gas stream can be passed, and which has a device for cooling at least one surface which comes into contact with the gas stream. The cooling device is formed in the context of the present invention as a cryocapacitor. A "cryocondensator" is understood here to mean a unit which can be flowed through by a suitable cryogenic refrigerant and which, as a result, makes contact on the surface which comes into contact with the gas flow Temperature, which can be adjusted so that a gaseous component separates from the gas stream at the surface. The in the

gaseous component deposited according to the invention is carbon dioxide, which is deposited in particular in solid form on the corresponding surface. Since the transition from the gaseous state takes place directly into the solid state, this is a desublimation. The desublimation takes place at a pressure and a temperature below the triple point of

Carbon dioxide (-56.6 ° C and 5.19 bar) is located. The cryocapacitor may have suitable surface structures, for example for enlarging the surface and / or for forming suitable collecting devices for the component deposited in solid form on the surface.

For the purposes of this application, a "carbon dioxide-rich and hydrocarbon-rich gas stream" is understood to mean a gas stream which is at least 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95% hydrocarbons, in particular methane, at a molar, Volume or mass basis. The remainder may consist entirely of carbon dioxide or in turn have at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95% carbon dioxide on a molar, volume or mass basis. Examples of such carbon dioxide-containing and hydrocarbon-rich gas streams are, for example, natural gas and biogas.

The separation units each have an otherwise closed region in which the cryocontainer is located, and can be traversed by the carbon dioxide-containing and hydrocarbon-rich gas stream. This is referred to here as a "separation room". The speed of the carbon dioxide-rich and hydrocarbon-rich gas stream, its pressure, its temperature and the temperature at the surface of the cryocapacitor are adjusted so that a desired proportion of each component to be separated, here carbon dioxide, deposits on the surface of the cryocapacitor. Ideally, the component to be separated would be completely removed from the carbon dioxide-rich and hydrocarbon-rich gas stream, but in practice, certain residual contents may also be acceptable. As previously mentioned, for example, by means of conventional carbon dioxide scrubbing, the carbon dioxide can usually only be removed to a residual content of about 3% from a corresponding carbon dioxide-containing and hydrocarbon-rich gas stream, but this for the purposes the earth or biogas treatment is insufficient. In contrast, according to the invention, much lower residual contents can be achieved, which are in any case less than 1%, in particular less than 0.5%, 0.4%, 0.3%, 0.2% or 0.1%. The invention allows

for example, by adjusting the flow velocity of

carbon dioxide-rich and hydrocarbon-rich gas stream to adjust this residual content of operational and / or economic demands. The system according to the invention can also be coupled at any time with pre- and / or post-purification steps, for example with adsorptive processes or with carbon dioxide scrubbing.

According to the invention, a corresponding installation has means which, for example as a valve arrangement (s), in particular with a suitable control device, are realized and arranged for, in a first operating mode, the refrigerant through the cryocondenser only the first separation unit and the gas flow through the separation room only the first Lead separator and the second

To heat separating unit and from the second separation unit a

withdrawing carbon dioxide-rich stream. These means are further adapted to lead in a second mode of operation, the refrigerant through the cryocapacitor only the second separation unit and the gas flow through the separation chamber only the second separation unit and to heat the first separation unit and deduct from the first separation unit a carbon dioxide-rich stream.

The invention thus proposes a plant operated with cryogenic capacitors

Separating carbon dioxide from a carbon dioxide-containing and

hydrocarbon-rich gas stream, in which two separation units can each be flowed through in alternating operation with the carbon dioxide-containing and hydrocarbon-rich gas stream. A changeover from a deposition in a first separation unit to a deposition in a second separation unit always takes place when the corresponding separation unit is there due to the separation unit

deposited amount of carbon dioxide is no longer operable and requires regeneration. This occurs, for example, by the fact that

Carbon dioxide (dry ice) firmly deposited on a surface of a cryocapacitor and thus insulating acts, so that with the carbon dioxide-containing and

hydrocarbon-rich gas stream coming into contact surface no

has sufficient temperature to achieve a predetermined degree of separation more. Switching can also take place in fixed time cycles. The cryocapacitor previously used for deposition is warmed up after switching (active or passive). As soon as the temperature at the surface of the

Cryo-condenser or in the separation unit exceeds a certain, pressure-dependent value, the carbon dioxide liquefies (above the triple point) or it sublimated (below the triple point). By appropriate pressurization (or a constant or reduce a previously set pressure) can thus win a liquid or gaseous carbon dioxide-rich stream and drain out of the plant. In the case of sublimation, a carbon dioxide-rich atmosphere from the condensation space can also be used using suitable gases

be pressed out (so-called purges).

It is understood that to remove the carbon dioxide from the respective

Time required for the separating unit to be shorter than the time during which the other separating unit is available for separating the carbon dioxide from the carbon dioxide-containing and hydrocarbon-rich gas stream. In this case, no more carbon dioxide is discharged from the corresponding separation unit, but this can already be pre-cooled and is then immediately available for a new separation cycle. It is therefore a further (third) mode of operation.

Any required pressure-temperature combinations, the skilled artisan easily removes the state diagram of carbon dioxide. Thus, a liquefaction of the carbon dioxide deposited in solid form can always be effected if a pressure of more than 5.19 bar, in particular a pressure of 6 to 100 bar, for example 6 to 20 bar, is maintained in the condensation space. The

Obtaining a liquid carbon dioxide-rich stream is particularly advantageous and allows a space and energy-saving storage of carbon dioxide. The system according to the invention has a number of other advantages. Thus, the removal of carbon dioxide, as proposed according to the invention, proves to be much less costly than deposition by means of carbon dioxide scrubbing.

In particular, no large quantities of washing media are required here, which have to be regenerated in a complicated and, in particular, high energy expenditure. With As can be mentioned, the residual contents of carbon dioxide which can be achieved in the system according to the invention are markedly lower than those for carbon dioxide washing.

In the context of the present invention, furthermore, only very small results

Gas losses, which at most by the regeneration of the respective

Cryo-condenser by sublimation of the carbon dioxide deposited thereon. The gas mixture present in a corresponding condensation space prior to the regeneration must then possibly be forced out of the condensation space together with the carbon dioxide-rich stream. However, these losses can be significantly reduced by converting the carbon dioxide from the solid to the liquid state, as explained above. Liquid carbon dioxide can be removed in this case very easily and with low losses via a bottom-side vent from the condensation space. Furthermore, the energy expenditure for the removal of carbon dioxide from the carbon dioxide-containing and hydrocarbon-rich gas mixture is extremely low, because no high temperatures for the regeneration of adsorbers are required. In contrast, a refrigerant used in the context of the invention can be obtained with comparatively low expenditure of energy and optionally (re) liquefied. The remaining energy expenditure is essentially composed of the pumping power required for feeding the corresponding media.

Also in terms of plant technology, the present invention proves to be simpler and less expensive, since a smaller number of components is required. The system according to the invention can also be adapted (scaled) to a wide variety of volume flows and can therefore be used, for example, in comparatively small biogas plants and in large tanker terminals in the same way. The invention can also be used for the removal of carbon dioxide from high pressure gases since it does not rely on the adjustment of certain pressure ratios (such as pressure swing adsorption).

In a system according to the invention, cryocapacitors are advantageously used in each case in the first and the second separation unit, which are set up for operation with liquid nitrogen or liquid natural gas as the refrigerant. These cryogenic refrigerants can be generated in other plants that anyway present at the respective location. For example, liquid nitrogen can be obtained in an air separation plant which is set up for the production of oxygen and in which liquid nitrogen is obtained as excess product. The liquid nitrogen can also be used in a vaporized form for further purposes after use in the system according to the invention, for example as pressure nitrogen for the mechanical system control and / or for inerting fire-prone areas of a corresponding natural gas plant. The use of liquid natural gas as a refrigerant proves to be particularly advantageous if the system according to the invention is implemented at a location of a natural gas liquefaction plant. Part of the liquefied natural gas can then be used as a refrigerant to remove carbon dioxide. A vaporized fraction can be re-liquefied at any time in the natural gas liquefaction plant. As with the use of liquid nitrogen can therefore be dispensed with a refrigeration cycle with a corresponding refrigerator. It goes without saying, however, that others too

Refrigerants or refrigerant mixtures can be used, which can be provided by means of a refrigeration cycle with a chiller.

As mentioned, in certain cases it may prove advantageous to provide means adapted to the carbon dioxide-containing and

hydrocarbon-rich gas stream to lead under pressure through the gas space of the first and second separation unit. A corresponding system proves to be particularly suitable in this case for the removal of carbon dioxide from a

corresponding compressed gas. The said means may be formed, for example, as pressure-resistant lines, valves, compressors, etc. In particular, means may also be provided which are adapted to set a corresponding pressure during the mentioned regeneration (either by holding, increasing or decreasing a prevailing pressure), so that the removal of the carbon dioxide from a corresponding condensation space or from the surface of the

Cryo-condenser by liquefaction or sublimation is possible.

To accelerate the regeneration (liquefaction or sublimation), a corresponding system can also be formed with separation units, each of which has a heating device. This allows a very quick transfer of the

Carbon dioxide in the desired state. A method for reducing a carbon dioxide content of a carbon dioxide-rich, hydrocarbon-rich gas stream, in which a plant is used as explained above, is also the subject of the present invention. In the method according to the invention, in the first operating mode, according to a first method alternative, the refrigerant is passed through the cryocapacitor only the first separation unit and the gas flow through the separation chamber of only the first separation unit and the second separation unit is heated and withdrawn from this a carbon dioxide-rich stream. In the second mode of operation - according to a second alternative method - the refrigerant is passed through the cryocapacitor only the second separation unit and the gas flow through the separation chamber only the second separation unit and the first separation unit heated and deducted from this a carbon dioxide-rich stream. The method according to the invention has the advantages explained above, to which reference is expressly made. As also mentioned, in such a method in the first

Operating mode in the separation chamber of the first separation unit and in the second operating mode in the separation chamber of the second separation unit and / or on the respective cryogenic condensers carbon dioxide deposited in solid or liquid form. Particularly advantageous is a deposit in solid form, because this allows a very extensive removal of carbon dioxide.

In particular, in the method according to the invention in the first operating mode, one surface of the cryocapacitor of the first deposition unit and in the second operation mode, one surface of the cryocapacitor of the second

Abscheideeinheit to a temperature of 180 to 220 K, in particular of 195 K, cooled. It has been found that this temperature range allows a particularly effective separation of carbon dioxide.

A corresponding method advantageously comprises passing the carbon dioxide-containing and hydrocarbon-rich gas stream in each case at a pressure of 5 to 50 bar through the corresponding separation chamber. The invention

Thus, as already mentioned, the method can also be used for high-pressure gases. The invention can be used with all hydrocarbon-rich and carbon dioxide-containing gas mixtures and is not limited to natural gas. The

Method is particularly suitable for biogas, sewage gas and / or landfill gas. The method according to the invention may also comprise, in each case, determining an amount of carbon dioxide in the first or second separation unit and in

Dependence thereof to switch from the first to the second operating mode or vice versa. It can be both the amount of deposited during deposition from a corresponding carbon dioxide-containing and hydrocarbon-rich gas stream as well as the amount of during regeneration yet

remaining carbon dioxide can be determined. Exceeds the amount of carbon dioxide formed during the deposition of a corresponding gas stream, for example, a default value, can be changed to the other operating mode. The same applies to the regeneration, with a here

Completeness of the removal can be determined.

To determine the amount of carbon dioxide in the first and the second

Separating unit, for example, an optical measuring method and / or a weighing device can be used.

The invention will be explained in more detail below with reference to the accompanying drawings, which show an embodiment of the invention.

Brief description of the drawings

Figure 1 shows a system according to an embodiment of the invention in

schematic representation in a first phase of operation

FIG. 2 shows the system according to FIG. 1 in a second operating phase.

Embodiments of the invention

In Figure 1, a system according to an embodiment of the invention is shown schematically in a first phase of operation and generally designated 1. The plant 1 can be fed via a line a a hydrocarbon-rich and carbon dioxide-containing gas stream A. To remove carbon dioxide from the gas stream A is a first separation unit 10 and a second

Separating unit 20 is provided. A gas stream B having a reduced carbon dioxide content obtained by means of a respective separation unit 10 or 20 can be discharged from the installation 1 via a line b.

The first separation unit 10 and the second separation unit 20 each have a cryocontainer 11 or 21, which is arranged in each case in a separating chamber 12 or 22 formed in the separation units 10 and 20, respectively. A deep-cold

Refrigerant C for supplying the cryocapacitors 11 and 21 can be provided via a line c and withdrawn via a line d. The lines c and d can also be connected, for example, to a chiller (not shown). In the example shown, however, it is also possible in particular for liquid nitrogen to be fed in as refrigerant C via line c and vaporized via line d (partially) and further used downstream in a suitable manner.

Via a line e can be deducted from the separation units 10 and 20 each have a carbon dioxide-rich stream (liquid or gaseous).

As mentioned several times, the system 1 according to the invention has means which are set up in a first operating mode, the refrigerant C by the cryocapacitor 11 only the first separation unit 10 and the

hydrocarbon-rich and carbon dioxide-containing gas stream A through the

Separating chamber 12 to lead only the first separation unit 10 and the second

To heat precipitator 20 and deduct from this the carbon dioxide-rich stream D. These means are further arranged in a second

Operating mode, the refrigerant C through the cryocapacitor 21 only the second separation unit 20 and the hydrocarbon-rich and carbon dioxide-containing gas stream A through the separation chamber 22 only the second separation unit 20 to lead and heat the first separation unit 10 and from this

carbon dioxide-rich stream D deduct. The illustrated in Figure 1

Operating state of the system 1 corresponds to the first operating state. The mentioned means are formed in the illustrated Appendix 1 as a first valve assembly 30 and as a second valve assembly 40. It should be emphasized that the term "valve arrangement" and the designation with corresponding reference numerals 30 and 40 are made solely for illustrative purposes, the mentioned means may also be designed differently and provided in particular in a different spatial arrangement. A part may be formed, for example in the form of directional valves, sliders and the like.

The first valve assembly 30 comprises the valves 31 and 32 in the lines f and g, in which the branched line a and the valves 33 and 34 in the lines h and i, which lead from the separation chambers 12 and 22 and to the Line b are united. Furthermore, the first valve arrangement 30 comprises the valves 35 and 36 which are arranged in the lines k and I, which lead from the cryo-condensers 11 and 21 and are combined to the line d.

The second valve arrangement 40 comprises the valves 41 and 42 in the lines m and n, in which the line c branches and the valves 43 and 44 in the lines o and p, the bottom side of the cryo-condensers 11 and 21 lead and then to the Line e be united.

In Appendix 1, in Figure 1 and in Figure 2, explained below, are active, i. lines traversed by a fluid, each with solid lines and arrows and non-active, i. empty and / or blocked lines each shown with dashed lines and arrows. The respective valves 31 to 36 and 41 to 44 which are in the blocking position are black, continuously connected valves 31 to 36 and 41 to 44 are shown in white.

In the operating mode shown in FIG. 1, the hydrocarbon-rich and carbon dioxide-containing gas stream A can flow through the lines a and f and the valve 31 into the separation chamber 12 of the first separation unit 10. By the same time through the lines c and m and the valve 41 into the cryocapacitor 11th

inflowing refrigerant C, which is discharged via the lines k and d and the valve 35, a temperature in the separation chamber 12 of the first

Abscheideeinheit 10 or on the surface of the cryocapacitor 11 so much reduced that carbon dioxide in the first separation unit 10 and on the Surface of the corresponding cryocapacitor 11 firmly separates. Therefore, via the lines h and b and the valve 33, the gas stream B can be withdrawn with a reduced carbon dioxide content. This is in the second separation unit 20 or on the surface of the

Cryo-condenser 21 already takes place in a previous cycle, so that here is a corresponding amount of carbon dioxide in solid form. Because the valves 42 and 36 are closed, no refrigerant C can flow through the lines c and n or I and d. As a result, a temperature in the separation chamber 22 of the second separation unit 20 or on the surface of the cryocapacitor 21 increases. This results in carbon dioxide depositing in liquid form at the bottom of the separation chamber 22 of the second separation unit 20 or this in the gas phase in the separation chamber 22 sublimated. This carbon dioxide, or a corresponding carbon dioxide-rich stream D, can be withdrawn via the lines p and e or the valve 44. In support, a gas stream may be used to push out a carbon dioxide-rich stream D from line p (not shown).

After the carbon dioxide is preferably completely from the separation chamber 22 of the second separation unit 20 and from the surface of the corresponding

Cryo-condenser 21 has been removed, the second separation unit 20 is again ready for the deposition of carbon dioxide. It can now be pre-cooled by opening the valves 42 and 36. If necessary, in particular if the amount of carbon dioxide in the first separation unit 10 or on the surface of the cryocapacitor 11 exceeds a predetermined value, the plant 1 is switched over to the operating mode shown in FIG.

The operating mode of the system 1 shown in Figure 2 differs from the operating mode of the system 1 shown in Figure 1 essentially by the respective inverse position of the valves 31 to 36 and 41 to 44. Therefore, now the first separation unit 10, as above with respect to Figure 1 and the second

Separator 20 explained, be regenerated. By contrast, the second separation unit 20 can be used to remove carbon dioxide from the gas stream A, as explained above with regard to FIG. 1 and the first separation unit 10.

Claims

claims

1. Annex (1), which aims to reduce the carbon dioxide content of a

carbon dioxide-rich and hydrocarbon-rich gas stream (A) is arranged, with a first and a second separation unit (10, 20) each having a in a separation chamber (12, 22) arranged and with a refrigerant (C) fed cryogenic condenser (11, 21) in which means (30, 40) are provided, which are adapted, in a first operating mode, the refrigerant (C) through the cryocondensator (1 1) of only the first separation unit (10) and the carbon dioxide-rich and hydrocarbon-rich gas stream (A) through the Separating chamber (12) only the first separation unit (10) to lead and the second

Heat separating unit (20) and deduct from the second separation unit (20) a carbon dioxide-rich stream (D), and which are further adapted, in a second operating mode, the refrigerant (C) through the

Cryo-condenser (21) only the second separation unit (20) and the

carbon dioxide-rich and hydrocarbon-rich gas stream (A) through the

Separating chamber (22) only the second separation unit (20) to lead and the first separation unit (10) to heat and deduct from this a carbon dioxide-rich stream (D).

2. Plant (1) according to claim 1, wherein the cryocapacitors (1 1, 21) of the first and the second separation unit (10, 20) are each configured for operation with liquid nitrogen or liquid natural gas as a refrigerant (C). 3. Plant (1) according to claim 1 or 2, are provided in the means for that

are furnished, the carbon dioxide-containing and hydrocarbon-rich

Gas flow (A) under pressure through the gas space (12, 22) of the first and the second separation unit (10, 20) to lead. 4. Plant (1) according to one of the preceding claims, wherein the first and the

second separation unit (10, 20) each having a heating device. A method for reducing a carbon dioxide content of a carbon dioxide-rich, hydrocarbon-rich gas stream (A) using a plant (1) according to any one of the preceding claims, wherein in the first operating mode the refrigerant (C) through the cryocondensator (11) only the first separation unit ( 10) and the carbon dioxide-rich and hydrocarbon-rich gas stream (1) passed through the separation chamber (12) only the first separation unit (10) and the second separation unit (20) heated and from this a carbon dioxide-rich stream (D) is withdrawn, and wherein in the second Operating mode the

Refrigerant (C) through the cryocapacitor (21) only the second separation unit (20) and the carbon dioxide-rich and hydrocarbon-rich gas stream (A) through the separation chamber (22) only the second separation unit (20) and the first separation unit (10) heated and off this one carbon dioxide-rich stream (D) is subtracted.

Method according to claim 5, wherein in the first mode of operation in the

Separating chamber (12) of the first separation unit (10) and in the second

Operating mode in the separation chamber (22) of the second separation unit (20) and / or on the respective cryogenic condensers (11, 21) carbon dioxide is deposited in solid or liquid form.

The method of claim 5 or 6, wherein in the first mode of operation, a surface of the cryocapacitor (11) of the first separation unit (10) and in the second mode of operation, a surface of the cryocapacitor (21) of the second separation unit (20) to a temperature of 180 to 220K,

in particular of 195 K, is cooled.

Method according to one of claims 5 to 7, wherein the carbon dioxide-containing and hydrocarbon-rich gas stream (A) each with a pressure of 5 to 50 bar through the corresponding separation chamber (12, 22) is passed.

Method according to one of claims 5 to 8, wherein the carbon dioxide-rich stream (D) in each case in liquid or gaseous form from the corresponding separation chamber (12, 22) is withdrawn.

10. The method of claim 9, wherein the carbon dioxide-rich stream (D) is formed by feeding a purge gas into the corresponding separation chamber (12, 22) under pressure.

11. The method according to any one of claims 5 to 10, wherein a natural gas stream, a

Biogas stream, a sewage gas stream and / or a landfill gas stream than the

carbon dioxide-rich and hydrocarbon-rich gas stream (A) is used.

12. The method according to any one of claims 5 to 11, wherein the nitrogen or

Liquefied natural gas is used as the refrigerant (C).

13. The method according to any one of claims 5 to 12, wherein each determines an amount of carbon dioxide in the first and second deposition unit (10, 20) and in response thereto from the first to the second operating mode or from the second to the first operating mode is switched.