DE2130774A1 - Synthesis gas sepn process by autorefrigeration - Google Patents

Abstract

In a superatmospheric autorefrigeration process for separating a gaseous mixture comprising hydrogen and carbon dioxide in to an enriched hydrogen product steam and unenriched carbon dioxide product steam, the gaseous feed stream is at a pressure of about 40 to 250 atmos. and is cooled so that 30 to 95% of the carbon dioxide is condensed by non contact counter-flow with the two departing product streams which are separately employed to cool the fractions of the feed stream. The temp. of the enriched carbon dioxide product steam and the temp. of the enriched hydrogen product stream are futher reduced by expansion to about the triple point of carbon dioxide without solid formation. A portion of the enriched carbon dioxide is recycled and combined with the feed to improve separation efficiency of the system.

Description

Process for the separation of carbon dioxide from a process gas The invention relates to an automatic cooling method for separating a gas mixture in one enriched low boiling point and one enriched higher boiling point Product flow. In a particular embodiment, automatic high-pressure cooling is used the gas mixture consisting essentially of C02 and 112 is cooled to such an extent that a considerable amount of CO 2 is selectively condensed and separated.

In the known processes for H2 production, an II2 and CO-containing gas mixture known as synthesis gas by, for example, partial oxidation of hydrocarbonaceous fuels or steam-hydrocarbon reforming generated. In the water gas equilibrium reaction, what is mixed with steam settles CO contained in a gas mixture when flowing over a catalyst. The received Gas mixture consists essentially of CO2 and H2 and can be small Shares Contains water vapor, gaseous hydrocarbons, CO and t12S. Finally will the enriched H2 product stream obtained from the gas mixture if the CO2 fraction and other impurities can be removed or reduced with the aid of the known Process of chemical treatment or solvent adsorption.

Common chemical processes for reducing CO2 from gas mixtures concern the CO2 adsorption in aqueous mono- or diethanolamine. Followed by a lye wash as well as the treatment with hot potash solution or water wash and subsequent adsorption in aqueous monoethanolamine. The gaseous impurities e.g. COS, CS2 and H2S, which are usually present in the synthesis gas, can be used with Solvents that do not adsorb CO2 form non-regenerable compounds.

In the processes currently used, C02 is produced from a flowing Gas mixture condensed out by cooling, with ice and C02 particles on the Lower the reactor walls and reduce the heat exchange performance. Also clog these particles block the passages and thereby prevent the passage of liquid. The moving parts of the apparatus, e.g. valves, cannot be used either. Further disadvantages of the current processes are that the separation of the C02 portion from the gas flow can only take place at pressures up to 57 atmospheres.

A main object of the present invention is to provide an improved automatic tubing process for the separation of large quantities (Shifted) synthesis gas or similar gas mixtures in two fractions: One liquefied Fraction enriched with C02 and a gaseous fraction enriched with H2.

Another object of the present invention is to provide an effective one it automatic cooling process for the separation of a High pressure gas flow of converted synthesis gas, the process pressures being essentially the synthesis gas pressures correspond.

Another task is the development of a drainage method a converted synthesis gas stream with overpressure and the condensation of 30-95% of the C02 and H2S without the use of external cooling systems.

Another task is to devise a method of removal of the C02 from a converted synthesis gas stream, with temperatures below the Triple point of C02 can be applied without the formation of a solid phase.

Finally, it is the object of the invention to provide a method for separation to work out a gas mixture that essentially contains H ″ and CO2 by adding at Atmospheric pressure of each of the separated product streams as a coolant for the separation of the C02 from the inlet gas is used and part of the separated CO2 is used the gas inlet is fed back in order to achieve an improved separation effect.

The solution to these objects according to the invention relates to a method for the separation of CO2 from a process gas, which CO2 and lower boiling gases, which contain or consist of hydrogen, mixed by a) the Process gas in a cooling zone under increased pressure above 7 atü to below the Dew point of the C02 contained in the process gas by countercurrent heat exchange with a Coolant is cooled, whereby C02 condenses out and so is in a separation zone a liquefied fraction with enriched C02 and a gaseous fraction with enriched 112 form; b) the liquefied fraction enriched with CO2 withdrawn from the separation zone and the cooling zone at a pressure which is reduced relative to the separation zone is supplied as part of the coolant required in the cooling zone; c) at the same time the gaseous fraction enriched with II2 is withdrawn from the separation zone and the cooling zone at a reduced pressure relative to the separation zone as a separate one and different further part of the coolant required in the cooling zone is supplied and is then withdrawn as a product stream.

In the method according to the invention, an im. essential 112 uiid C02-containing gas mixture into an enriched H2 product stream and an enriched C02 product stream separated. Most of the unwanted H2S comes along with separated from the CO2 stream be fed dry. Or there will be drying in the following procedure carried out, with no significant drop in the total pressure occurs: The wet Gas stream at a pressure of about 40-250 atmospheres can be dried by in a first cooling zone with a coolant to be described later in countercurrent heat exchange the gas stream is cooled to a temperature below the melting point of the water will. The condensed water is separated from the gas stream in a first separation zone. The gas stream is then completely dehydrated by passing it over aluminum oxide.

The gas stream dried in this way is split into two parts in such a way that that there is a maximum heat exchange. After the individual streams in a second and third cooling zone in the countercurrent heat exchanger cooled down with separate coolants were, the union took place.

In a fourth cooling zone, the precooled gas flow is countercurrently exchanged with a coolant to a temperature of about -48 - -50C, below the C02 melt zpun1ct, cooled down. Depending on the respective pressure, about 30-95% C02 is released from the Gas flow along with about 4% H2, 90% of the H2S and small proportions CO, CH4, N2 and Ar condensed. In a second separation zone, the enriched liquid CO2 phase separated from the enriched gaseous H2 phase. These two Phases form the product streams. When the triple point temperature of the CO2 in the separation zone is reached, the condensed C02 portion increases, while that in the liquid CO dissolved H2 portion remains essentially unchanged.

The temperature of the liquefied CO2 product stream is then increased adiabatic isenthalpic expansion with the help of a first throttle to about -54 - -56.50C, above the triple point of CO2, without a solid phase being formed, lowered. The product stream cooled in this way is then passed through a fourth, the second and sent to the first cooling zone, with coolant and in countercurrent heat exchange Gas stream are guided.

Similarly, if more cooling, e.g.

at the start of the process, it is necessary to set the temperature of the gaseous enriched H2 product stream to about -54 - -73 ° C without the formation of a solid phase lowered by adiabatic isenthalpic expansion with the aid of a second throttle. The gaseous H2 stream cooled in this way then flows through the third cooling zone during in countercurrent heat exchange between part of the inlet gas stream and one Coolant heat exchange takes place.

Provision is made for returning part of the fortified C02 product flow on the gas flow inlet and the production of a gas inlet pressure corresponding pressure. This recirculated gas flow is combined with the fresh gas flow mixed to achieve an improved release effect. By adiabatic isentropic Expansion becomes another part of the enriched CO2 product stream to one temperature cooled from about 7800 and about atmospheric pressure without forming a solid phase, an additional coolant and partially condensation agent for the counterflow To get gas.

In particular through matorial and thermal equilibrium; Certain cases can perform the tasks of the various cooling zones in one or more cooling zones be combined; or if it is appropriate, an additional cooling zone can be built in will.

A preferred embodiment of the method according to the invention is the attached drawing shows the separation of C02, 1125 and H20 water-saturated converted synthesis gas -represents. Of course you can the method according to the invention also applies to the separation and rewinding of others a selective liquefaction accessible gases within the present process prevailing temperatures and pressures are applied: At the inlet (1) flows a Wet gas mixture with a pressure of about 98 atü in the pre-cooler (2), where a Temperature decrease to below the dew point of that contained in the gas mixture Water vapor (about 6-1 80C) by countercurrent heat exchange with the enriched CO2 product stream (3) takes place. Most of the gas is in the pre-cooler (2) contained water condenses. The water is collected in the separator (4) and uoer (5) removed.

The (4) leaving overhead, partially dried gas stream is passed through (6) in (7) or (8), where the remainder is water vapor of the gas mixture at suitable Substances such as aluminum oxide or. Silica gel, is adsorbed. The parallel connection the two dryers (7) and (8) allows the regeneration of a dryer while at the same time the treatment of the gas mixture is continued in the other dryer. This arrangement will be described in detail later. Is the gas flow of the plant already supplied dried by using one of the common gas drying methods the part of the overall system that includes drying can be omitted.

The dried gas mixture at essentially the same pressure as the inlet pressure corresponding pressure enters the separation system via (5G) and is divided into the fractions (9) and (10) divided. The fraction is cooled in the cooler (11) (9) to a temperature of around -20 - -290C, indene for the heat exchange of the enriched CO2 product stream (12) is guided in countercurrent. The fraction (10) is in the cooler (13) cooled down to about -17 - -23 ° C, with countercurrent heat exchange in (13) takes place with enriched H2 product stream (14). The fractions (9) and (10) are combined and flow via (15) into the cooler (16). Here is a temperature decrease to below the dew point of C02 (about -48 - -5140C), but above the CO2 triple point (about -56.5 ° C), through countercurrent heat exchange with enriched CO2 product flow (17) made. The coolers (11), (13) and (16) condense about 30-95 mol% CO2 and H2S along with 8-35 mol% of other gaseous ones present in the gas mixture Components.

The enriched liquid CO2 flows through (18) together with the uncondensed part of the gas mixture, which is about 80-95 mol% H2 and about 65-85 Mol- Ar, CO, N2 and still 10-35 mol-% C02 and H2S, into the separator (19).

At the beginning the check valve (20) is closed and the enriched one H2 product stream is overhead at (19) through (21), via the valve (26) and the Relief valve (22), where the pressure is reduced from about 98 atmospheres to around 10 atmospheres is led. During the expansion in (22), the gas temperature drops to about -610C (below the triple point of CO2) without the formation of a solid phase. The enriched H2 product gas flows through (14) into (13) and is here in countercurrent heat exchange used as a coolant to remove the heat from fraction (10). The out (13) Resulting enriched H2 product stream at a temperature of about 1.5-100C passes through (23) into the collector (24) and is via (25) for the following Use, for example in oil shale pyrolysis, of non-catalytic s hydrogenation of petroleum products or in a desired further purification.

Higher cooling capacities are possible if that comes from (21) Under-high pressure gas does not undergo expansion at constant enthalpy in (22), but is expanded at constant entropy. That means, that the gas is an expansion machine or the rotor of a turbo-electric, not shown here Generator drives.

After the start of the process it is due to decreasing loading of the cooler (13) is no longer necessary, (13) to supply a coolant at -68 ° C. Valve (26) is then closed and the enriched H2 product gas is through (21) via the check valve (20) into the cooler (13) with a temperature of about -48 - -540C initiated. This procedure avoids a large pressure drop 1 via the expansion valve (22). The enriched product gas is then over (25) discharged at a temperature of about 1.5-10 ° C at a pressure that is essentially equal to the pressure of the gas mixture entering in (i), reduced by that in the course of the process occurring pressure losses, is. The enriched H2 product gas contains: 75-85 Vol% H2; 9-18 vol% CO2; 3-7% by volume CO; 1-3 vol methane; 0.04-0.2 vol% H2S; 0.1-0.2 Vol-% N2 and 0.02-0.1 Vol- Ar.

The enriched liquid CO2 passes through the bottom of the separator (19) (27) is withdrawn at about -48 - -54 ° C and passes through the expansion valve (28). at the expansion via (28) cools the liquid, enriched CO2 to around -550C without formation of a solid phase, while the pressure from about 98 atü to about 5.5 atü drops. As already described, there is now a series of three successive ones Countercurrent heat exchange processes in the coolers (i6), (11) and (2) between the enriched CO2 product stream and the counter-flowing gas mixture until the CO2 electricity leaves the system. The liquid, enriched one evaporates in the cooler (16) C02 product stream, arrives from (16) via (12) in (11) with a temperature of approx -45 - -54 ° C. In (11) the enriched CO2 product stream is heated before it (11) via (60) leaves. When the valves (61) and (80) are closed, the CO2 electricity in (2) via (81) and (3) with a temperature of about -21 ° C.

The temperature of the converted synthesis gas in the pre-cooler (2) is kept above the freezing point of the condensed water to the line to To protect the separator (4) from icing and blocking. The temperature control in (2) takes place with the help of the shunts (82) and (83) and the valve (80).

A side stream of approximately 0.028-0.085 m3 / minute of enriched CO2 product stream through (60) can be used to discharge the in the dryers (7) and (8) in the reactivation circuit serve adsorbed water. The dryers (7) and (8), consisting of 'white adsorbers, are connected to each other via a shuttle valve with manual switching, and the after to be able to perform eight hours reversal in a continuous process.

Each adsorber contains enough activated adsorbent around water dew points Can be reached in the temperature range of -67 ° C when water is at the saturation temperature up to 37 ° C.

The reactivation is achieved by heating the exhausted adsorber in about four hours with the help of ileice elements arranged in the adsorbent rich t. During this time, the sewage gas removes the remaining water. This is followed by cooling with continued gas purging for a further four hours. A sufficient number of valves in the manifold connecting the adsorbers ensures for the control of the gas streams brought in for adsorption or reactivation and to release excess pressure or to build up higher pressures. For example, will the dryer - (7) by opening the valves (61) - (62) - (63) - (64) and closing of the valves (65) - (66), and introduction of enriched CO2 product gas into (7) via (67) - (68) - (69) - (70), reactivated. The flushing gas laden with water leaves (7) then via (71) - (72) - (73) - (74) and can, if necessary, the circulation (33) are fed back.

The one escaping from (2) at a temperature of about -9 ° C enriched CO2 stream is fed into (30) via (29) and collected there. From (30) to (31) and the outlet (32) the CO2 can be used for subsequent use, for example in urea production (after further cleaning beforehand), incinerated for sulfur recovery or for energy generation. The enriched CO2-Produk @ gas is at the exit (32) with a temperature of about -9.0 ° C and a Pressure of about 5.5 atm available. It contains; 70-80 vol% CO2; 15-30 vol% H2; 2-4 Vol% CO; 0.2-0.9 vol% H2S; 0.5-1.9% by volume methane; 0.02-0.10 vol% N2 and 0.03-0.08 Vol% Ar.

About the "separating effect" of the system, defined as the number of CO2 moles in the enriched CO2 product stream divided by the total number of CO2 moles in the converted To improve syngas input flow multiplied by 100, eill becomes part of the The separated C02 is returned to the input as a bypass flow. Part of the enriched CO2 product gas stream can be returned to the cycle compressor (34) via (31) and (33) where the C02 gas receives the necessary process pressure again. Takes place from (34) via (35) the return to (1), where it is converted with the incoming syngas is mixed. The advantages of this mode of operation are discussed later.

If a lower temperature to condense out during operation If more C02 is required, the temperature sensor (36) sends a signal to the temperature control (37) given to open the valve (28) to release more liquid C02 via (17) at (16) provide. If the liquid level in (19) falls, a control signal is given from the level measurement (38) to the level control '(39) to the control valve (40) open. As a result, a larger return flow is achieved from (33). That An increase in the return speed causes an increase in the proportion of CO2 and it more CO2 is available for cooling and condensation in (2), (11), (16) and (19). If the liquid level in (19) is too high, becomes a control signal from the level measurement (38) to the level control (39) to close the control valve (40) given. This reduces the return speed and the returned CO2 part, so that less CO2 is given to (1). In this particular return control the level in (19) is determined by the amount of return flow and the temperature III (19) controlled.

By lowering the temperature in (19) becomes an increasing amount C02 and H2S condensed out of the gas stream, with the H2 loss in the enriched CO2 product flow is relatively constant. For example, when printing 98-99 atü and a separator temperature in (19) of -51 ° C, 82% CO2 and 85% H2S obtained while at a temperature of -s4 c 90% CO2 and 92 ao H2S are obtained will.

The task of the return flow is to make the portion condensable Increase C02 from the gas stream. More in (19) condensed liquid CO2 allowed a drop in temperature in the separator. The return is below when printing 98 atii more effective than at higher working pressures, because this increases the temperature to the C02 Taupun middle temperature appropriate pressure influenced wii d. The C02 dew point is directly from the partial pressure and inversely proportional to the separator temperature dependent.

The volume of the enriched CO2 return flow (33), which for an influence on the desired CO2 condensation is required, can be done with the help of known methods can be determined.

Another embodiment of the present invention is that the cooling effect by adiabatic isentropic expansion of the whole or a part of the enriched CO2 product gas from (32) can be improved, whereby the coolant - without the formation of a solid phase - a temperature of about -79 ° C and a pressure of 1 atmosphere reached. This coolant can be used in countercurrent heat exchange with the gas flow in (2), (11), (13) or (16) or a part of it is available for the coolers belonging to (34).

The following examples are provided to aid understanding of the present Invention reproduced, but do not limit the invention to this . Material flows,, gas analyzes and process conditions are in the for example 1 associated Table I is given.

Example I: About 169 kg / hour heavy fuel oil with the API density 12.8, a combustion value of 10 kcal / kg and the analysis result (in% by weight) of C: 84.08; H2: 10.60; S: 4.51, are with 169 kg / hour O2 (95 vol-) in a synthesis gas generator, which corresponds, for example, to that described in US Pat. No. 2,582,938. The temperature in the reaction zone was 933dC, the pressure 103 atm.

About 385 kg / hour of crude synthesis gas containing essentially 48.58 Mol-Qp 112 and 40.23 mol% CO were supplied by the generator, which was quenched directly was cooled with water below 316 ° C. The cooled gases were washed with water, heated to around 400 C and put into a converter (shift converter) at around 105 Atü mixed with Dalnpf passed over a suitable catalyst, e.g. iron oxide.

About 179 kg / hour of water-saturated shifted synthesis gas and about 2.3 kg / hour of CO2 circulated are according to drawing at (i) introduced into the CO2 condensation plant. About 36 grams / hour of water were used at (2) condensed from the gas mixture and removed from the system in (4). Additionally 8.9 grams / hour of water vapor was removed in dryers (7) and (8). The dry gas analysis is given in Table I.

TABLE I material flows m3 / h kg / h moles / h synthesis gas at (1) 232 180 21.6 anger. CO2 product flow at (32) 81 110 7.5 anger. H2 - "" at (25) 118 44 10.9 fraction (9) 65 50 6.0 fraction (10) 188 145 17.4 dry gas analysis Inlet gas activated CO2 product activated H2 product stream current % By volume kg-mole / h% by volume kg-mole / h% by volume kg-mole / h H2 57.07 4.78 25.34 0.87 78.93 3.91 CO2 34.66 2.90 68.82 2.35 10.74 0.53 CO 5.06 0.43 3.62 0.10 6.49 0.32 CH4 2.91 0.24 1.87 0.06 3.56 0.18 H2S 0.06 0.005 0.25 0.008 0.04 0.002 N2 0.16 0.014 0.04 0.001 0.16 0.008 Ar 0.08 0.007 0.06 0.002 0.08 0.004 Total 100.0 8.376 100.00 3.391 100.00 4.954 Mid- leres Molge weight 18.3857 32.2328 8.7972 Process conditions a) Temperatures in ° C cooler (2) (11) (13) (16) Jacket, inside -21.1 -54 -61.1 55.6 outside 11.7 -21.1 3.3 -54 Cool beating, inside 21.1 8.9 8.9 -20.6 outside 8.9 -26.7 -20.0 -54 b) Pressure in atmospheric inlet stream at (1): 99.8 anger. CO2 product stream at (32): 5.6 anger. H2 product stream at (25): 9.8 at the beginning of 98 during operation TABLE II return temperature CO dew inlet gas inlet gas anger. anger. CO2 above (33) in (19) point with return CO2 product H2 product Separation effect m3 / h ° C ° C% CO2% H2% CO2% H2% CO2% H2% CO2% H2% 0 -38.9 - 3.55 33.30 62.33 33.30 62.33 74.09 22.03 16.69 78.49 62.2 2.5 -41.2 -3.17 33.30 62.33 33.69 61.93 72.97 21.97 17.20 78.70 63.2 4.8 -43.6 -2.72 33.30 62.33 34.02 61.59 75.61 22.27 15.58 79.10 67.0 6.8 -45.6 -2.33 33.30 62.33 34.46 61.29 78.11 22.56 13.92 79.53 70.8 8.7 -47, 8 -1.95 33.30 62.33 34.85 61.03 80.48 22.84 12.23 79.97 74.6 10.5 -47.2 -1.50 33.30 62.33 35 .24 60.79 82.73 23.09 10.51 80.42 78.4 11.3 -51.1 -1.28 33.30 62.33 35.43 60.68 83.80 23.21 9 , 64 80.65 80.3 The drying gas stream was divided into fraction (9), about 50 kg / hour and fraction (10), about 145 kg / hour.

Fraction (9) was ill the cooling coils full (11) and fraction (10) entered into that of (13). The fractions were cooled and combined introduced in (16) where 81.5% of the CO2 and H2S along with small amounts of others Gases were condensed from the gas stream. Analysis of these condensed gases can be found in Table I and is there as "enriched CO2 product stream" designated. This product stream is separated from the uncondensed gases in (19). The analysis of the uncondensed gases is also given in Table I. and is referred to as the "enriched H2 product stream". This product stream contains about 87% of the 112 present in the gas mixture. About 110 kg / hour of enriched CO2 product streams were expanded via (28) and the cooled product was sequentially into the jacket surrounding the cooling coils for the one to be carried out with the gas mixture Countercurrent heat exchange given at (16), (11) and (2). About 43.5 kg / hour des enriched H2 product stream are expanded in an analogous manner at (22) and the cooled product is poured into (13) as a coolant.

The temperatures and pressures of the various streams at the respective Appendix points are given in Table I.

Example II: 10.8 kg-moles / hour of a gas stream at 3.6 kg-moles / hour CO2 is introduced into the CO2 condensation system at a pressure of 99.86 atmospheres.

From the results of Example II, summarized in Table II, the result is that the condensed proportion of CO2 can grow from 62.2 to 80.3%, if the proportion of the enriched CO2 product gas carried in the return via (33) and (35) is increased.

As the volume of the circulating gas increases, the gas drops Temperature in (59), the CO2 separation effect increases and the CO2 content in the enriched H2 product flow decreases sharply, while the H2 portion in the enriched CO2 product flow changes slightly.

Without CO2 backfilling, 2.93 kg-moles / hour become enriched CO2 product gas containing 2.17 kg-moles / hour of CO2 at -39 ° C. As already described in detail about 80% of the CO2 present in the input mixture is condensed out, if in (19) - 51 ° C are reached. The separator temperature actually required in (19) and return speed to achieve a desired separation effect at a constant initial separator temperature and input speed can -experimentally or calculated with the aid of scanned methods.

The inventive method has been described in general and by way of examples, the gaseous starting materials of various composition and prints used, backed up for better understanding and illustration to get. From the foregoing it will be clear that various procedural modifications and other starting materials can be used without departing from the scope of the invention is left.

Claims (12)

P a t e n t a n 9 p r ii c b e 1. Process for the separation of CO2 from a process gas, which CO2 and lower boiling gases containing or consisting of hydrogen, mixed contains, characterized in that a) the process gas in a cooling zone under increased Pressure above 7 atü to below the dew point of the C02 contained in the process gas is cooled by countercurrent heat exchange with a coolant, with CO 2 condensing out and a liquefied fraction with enriched C02 and form a 6-ds-shaped fraction with enriched H2; b) the liquefied with CO2-enriched fraction withdrawn from the separation zone and the cooling zone at rela tively reduced pressure to the separation zone as part of that required in the cooling zone Coolant is supplied; c) at the same time the gaseous one enriched with 112 Fraction withdrawn from the separation zone and the cooling zone at relative to the separation zone reduced pressure as a separate and distinct further part of the in the cooling zone required coolant is supplied and then as a product stream is deducted. 2. The method according to claim 1, characterized ennze lehne t that a part to maintain the flow of coolant enriched with CO2 that comes out of the cooling zone a uniform pressure of the process gas flow is compressed again and the thus compressed CO 2 stream with the incoming process gas to improve the CO2 separation effect is mixed. 3. The method according to claim 1, characterized in that the pressure reduction the liquefied fraction enriched with C02 by expansion through a throttle is effected, the CO 2 fraction cooling to about -48 - -56 ° C. 4. The method according to claim 1, characterized in that the pressure reduction the gaseous fraction enriched with H2 is effected by expansion, wherein the gaseous fraction enriched with 112 is cooled to about -54 - -79 ° C, without a solid phase being formed. 5. The method according to claim 4, characterized in that at least part of the gaseous fraction enriched with H2 by expansion in a Expansion device is cooled to about -54 - -79 ° C. 6. The method according to claim 4, characterized in that at least a part of the gaseous fraction enriched with 112 by expansion over a The throttle is cooled to around -54 - -73 ° C. 7. The method according to claim 1, characterized in that the entire C02-enriched coolant coming from the cooling zone or part of it is cooled to -54 --79 ° C and reduced to low pressure by adiabatic isentropic expansion in a gas turbine without the formation of a solid phase, whereby additional Coolant is available for process gas cooling. 8. The method according to claim 1, characterized in that the with H2-enriched gaseous product stream is withdrawn at a pressure that is not is significantly lower than the process gas pressure. 9. The method according to claim 1, characterized in that first one The process gas is dried in a cooling zone. IO.Verfahren according to claim 9, characterized in that the drying however, by cooling in the cooling zone to below the dew point of the water vapor above the dew point of the CO2 contained in the process gas through countercurrent heat exchange takes place with the coolant, whereby the condensation of part of the water occurs, the water is separated from the non-condensed gases in a separation zone and the non-condensed gases are dewatered in a dry zone. 11. The method according to any one of the preceding claims, characterized in, that a converted (shifted) synthesis gas into a product stream enriched with CO2 and separating a gaseous H2-enriched product stream by a) a synthesis gas flow at overpressure in countercurrent heat exchange step by step in a plurality of separate cooling zones is cooled, b) in each separate cooling zone one of two cooling liquids with different compositions, the following are produced in the process, enters into heat exchange with a synthesis gas stream, the cooling of the synthesis gas stream to below the dew point at a given Synthesis gas pressure takes place, c) in mindes-tells one of the separate Cooling zones the synthesis gas stream is split into individual tones and each individual stream enters into heat exchange with separate product streams of different composition and d) separation into a liquefied CO 2 enriched product stream and a gaseous product stream enriched with H2 in a gas-liquid separation zone he follows; e) at least part of the liquefied C02-enriched product stream withdrawn from the separation zone and at essentially the same temperature at which the CO2 stream was withdrawn, expanded and the expanded stream through at least a cooling zone as a cooling liquid at a pressure which is reduced relative to the separation zone and finally the product stream enriched with C02 as a gaseous phase is withdrawn at a higher temperature than that prevailing in the separation zone; f) at the same time at least part of the gaseous product stream enriched with H2 withdrawn from the separation zone and as a second coolant stream through at least one Cooling zone, which is different and separated from the cooling zones, which by the first Coolant flow is cooled, is sent, and g) the gaseous enriched with H2 Product stream at a temperature which is higher than the temperature of the separation zone is withdrawn. 12. The method according to claim 11, characterized in that the converted Synthesis gas stream has a low H2S content, which essentially consists of the Synthesis gas flow through condensation and mixing with that enriched in C02 Product gas stream is removed.