PROCESS AND PLANT FOR PRODUCING A SYNTHESIS GAS PRODUCT STREAM HAVING AN ADJUSTABLE H2/CO RATIO AND A PURE HYDROGEN STREAM

Abstract

Proposed are a process and a plant for producing a synthesis gas product stream having an adjustable H.sub.2/CO ratio and a pure hydrogen stream, wherein it is provided according to the invention that a substream of a deacidified synthesis gas stream is supplied to a membrane separation plant fitted with a hydrogen-selective membrane and the remaining substream is supplied to a pressure swing adsorption plant, wherein the latter affords a pure hydrogen stream and a fuel gas stream. The hydrogen-enriched permeate stream obtained from the membrane separation is likewise supplied to the pressure swing adsorption plant, thus enhancing the yield of pure hydrogen. The hydrogen-depleted retentate stream obtained from the membrane separation is discharged as a synthesis gas product stream and if of a suitable composition may be utilized as oxo gas.

Claims

1. A process for producing a synthesis gas product stream having an adjustable hydrogen-carbon monoxide ratio (H.sub.2/CO ratio) and a pure hydrogen stream from an input stream containing hydrocarbons, comprising: (a) providing the input stream containing hydrocarbons; (b) supplying the input stream containing hydrocarbons to a synthesis gas production plant comprising: (b1) a steam reforming stage, or (b2) an autothermal reforming stage (ATR), or (b3) a partial oxidation stage (POX), or (b4) a combination of at least two of the stages (b1) to (b3); (c) at least partial conversion of the input stream containing hydrocarbons in the synthesis gas production plant under synthesis gas production conditions to afford a raw synthesis gas stream containing hydrogen (H.sub.2) and carbon monoxide (CO); (d) discharging a raw synthesis gas stream from the synthesis gas production plant; (e) introducing at least a first proportion of the raw synthesis gas stream into a CO conversion plant comprising at least one CO conversion stage, converting the proportion of the raw synthesis gas stream introduced into the CO conversion plant under CO conversion conditions to afford a converted synthesis gas stream, discharging the converted synthesis gas stream; (f) introducing the raw synthesis gas stream and/or the converted synthesis gas stream into a sorption apparatus for removal of acidic gas constituents, especially carbon dioxide and hydrogen sulfide, using a physical or chemical sorption process, discharging a deacidified synthesis gas stream from the sorption apparatus; (g) introducing at least a second proportion of the deacidified synthesis gas stream into a first hydrogen enrichment stage containing a hydrogen selective membrane as the separating means, separating the deacidified synthesis gas stream into a hydrogen-enriched permeate stream and into a hydrogen-depleted retentate stream; (h) introducing the hydrogen-enriched permeate stream and the proportion of the deacidified synthesis gas stream not passed to the first hydrogen enrichment stage into a second hydrogen enrichment stage operating according to the principle of pressure swing adsorption (PSA); (i) discharging a pure hydrogen stream and a carbon monoxide-containing residual gas stream from the second hydrogen enrichment stage; and (j) discharging the hydrogen-depleted retentate stream from the first hydrogen enrichment stage as a synthesis gas product stream, wherein the first proportion and/or the second proportion are chosen such that the molar H.sub.2/CO ratio required for the synthesis gas product stream is obtained.

2. The process according to claim 1, wherein the first proportion is between 0% and 100% of the raw synthesis gas stream and/or the second proportion is between 0% and 100% of the deacidified synthesis gas stream.

3. The process according to claim 1, wherein a third proportion of the carbon monoxide-containing residual gas stream is passed into the synthesis gas product stream and the first proportion and/or the second proportion and/or the third proportion are chosen such that the H.sub.2/CO ratio required for the synthesis gas product stream is obtained.

4. The process according to claim 3, wherein the first proportion is between 0% and 100% of the raw synthesis gas stream and/or the second proportion is between 0% and 100% of the deacidified synthesis gas stream and/or the third proportion is between 0% and 100% of the carbon monoxide-containing residual gas stream.

5. The process according to claim 1, wherein the molar H.sub.2/CO ratio of the synthesis gas product stream is between 10 and 0.1 mol/mol.

6. The process according to claim 1, wherein the raw synthesis gas stream less the first proportion is directly supplied to the sorption apparatus.

7. The process according to claim 1, wherein the deacidified synthesis gas stream less the second proportion is directly supplied to the second hydrogen enrichment stage.

8. The process according to claim 3, wherein the residual gas stream less the third proportion is discharged from the process as fuel gas.

9. The process according to claim 1, wherein the carbon monoxide-containing residual gas stream is compressed before supplying to the synthesis gas product stream.

10. The process according to claim 1, wherein the carbon monoxide-containing residual gas stream is supplied to a fine purification stage before supplying to the synthesis gas product stream or is supplied to a joint fine purification stage after supplying to the synthesis gas product stream.

11. The process according to claim 1, wherein the hydrogen-enriched permeate stream is compressed before supplying to the second hydrogen enrichment stage.

12. A plant for producing a synthesis gas product stream having an adjustable hydrogen-carbon monoxide ratio (H.sub.2/CO ratio) and a pure hydrogen stream from an input stream containing hydrocarbons, comprising the following assemblies and constituents in fluid connection with one another: (a) means for providing the input stream containing hydrocarbons, (b) a synthesis gas production plant comprising means for supplying the input stream containing hydrocarbons to the synthesis gas production plant, the synthesis gas production plant further comprising: (b1) a steam reforming stage (SMR), or (b2) an autothermal reforming stage (ATR), or (b3) a partial oxidation stage (POX), or (b4) a combination of at least two of the stages (b1) to (b3); (c) means for discharging a raw synthesis gas stream containing hydrogen (H.sub.2) and carbon monoxide (CO) from the synthesis gas production plant, (d) a CO conversion plant comprising at least one CO conversion stage, means for dividing the raw synthesis gas stream and means for introducing at least a first proportion of the raw synthesis gas stream into the CO conversion plant, means for discharging a converted synthesis gas stream; (e) a sorption apparatus suitable for removal of acidic gas constituents, especially carbon monoxide and hydrogen sulfide, using a physical or chemical sorption process, means for introducing the raw synthesis gas stream and/or the converted synthesis gas stream into the sorption apparatus, means for discharging a deacidified synthesis gas stream from the sorption apparatus; (f) a first hydrogen enrichment stage containing a hydrogen-selective membrane as the separating means suitable for separating the deacidified synthesis gas stream into a hydrogen-enriched permeate stream and into a hydrogen-depleted retentate stream, means for dividing the deacidified synthesis gas stream and means for introducing at least a second proportion of the deacidified synthesis gas stream into the first hydrogen enrichment stage, means for discharging the hydrogen-enriched permeate stream and the hydrogen-depleted retentate stream; (g) a second hydrogen enrichment stage operating according to the principle of pressure swing adsorption (PSA), means for introducing the hydrogen-enriched permeate stream and the proportion of the deacidified synthesis gas stream not passed to the first hydrogen enrichment stage into the second hydrogen enrichment stage; (h) means for discharging a pure hydrogen stream and a carbon monoxide-containing residual gas stream from the second hydrogen enrichment stage; and (i) means for discharging the hydrogen-depleted retentate stream from the first hydrogen enrichment stage as a synthesis gas product stream.

13. The plant according to claim 12, wherein the means for dividing the raw synthesis gas stream and the means for dividing the acidified synthesis gas stream are constituted such that the first proportion and/or the second proportion can be chosen such that the molar H.sub.2/CO ratio required for the synthesis gas product stream is obtained.

14. The plant according to claim 12, further comprising means for dividing the carbon monoxide-containing residual gas stream and means for introducing a third proportion of residual gas stream into the synthesis gas product stream, wherein the means are constituted such that the first proportion and/or the second proportion and/or the third proportion can be chosen such that the H.sub.2/CO ratio required for the synthesis gas product stream is obtained.

15. The plant according to claim 12, further comprising means which allow the carbon monoxide-containing residual gas stream to be compressed before supplying to the synthesis gas product stream.

16. The plant according to claim 12, further comprising means which allow the carbon monoxide-containing residual gas stream to be subjected to a fine purification before supplying to the synthesis gas product stream or subjected to a joint fine purification after supplying to the synthesis gas product stream.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Developments, advantages and possible applications of the invention are also apparent from the following description of exemplary embodiments and the drawings. All the features described and/or shown in images, alone or in any combination, form the invention, irrespective of the way in which they are combined in the claims or the dependency references therein.

[0052] In the figures:

[0053] FIG. 1 is a first example of a process/a plant for producing an oxo gas according to the prior art,

[0054] FIG. 2 is a second example of a process/a plant for producing an oxo gas according to the prior art,

[0055] FIG. 3 is a third example of a process/a plant for producing an oxo gas according to the prior art,

[0056] FIG. 4 is an exemplary embodiment of a process/a plant according to the invention for producing an oxo gas.

DETAILED DESCRIPTION OF THE INVENTION

[0057] FIGS. 1 to 4 are in the form of block flow diagrams which show the essential functional blocks and important connection conduits between these without showing individual fittings and equipment parts such as for example heat exchangers, heaters, coolers, valves, mixing apparatuses, connecting apparatuses, dividing apparatuses, pumps, blowers and compressors separately. A person skilled in the art will be able to select and dimension fittings and equipment parts with reference to his knowledge of the art via general requirements for the respective function block and/or subsequent specific requirements. The same applies for any required auxiliary streams, for example the steam required as a reaction partner in CO conversion.

[0058] In the block flow diagram shown in FIG. 1 according to a first example of the process/of the plant according to the prior art, conduit 11 passes a proportion of a raw synthesis gas produced for example using a synthesis gas production plant (not shown) which is configured as a steam reforming stage, as an autothermal reforming stage, as a partial oxidation stage or as a combination of at least two of the abovementioned synthesis gas production stages to a CO conversion plant 10 comprising at least one CO conversion stage and introduces it into said stage. The CO conversion plant converts the introduced proportion 1 of the crude synthesis gas stream under CO conversion conditions into a converted synthesis gas stream which is subsequently discharged from the CO conversion plant via conduit 14. The conduit 12 arranged as a bypass is used to run the remaining proportion of the raw synthesis gas past the CO conversion plant and directly into the conduit 14.

[0059] The mixed gas stream obtained from converted synthesis gas and unconverted raw synthesis gas is introduced via conduit 14 into a sorption apparatus 20 for removal of acidic gas constituents, especially carbon dioxide and hydrogen sulfide, by means of a physical or chemical sorption process. This may be configured for example as a gas scrubbing with cryogenic methanol as the absorbent/scrubbing medium according to the Rectisol process known per se. Conduit 22 then effects discharging of a deacidified synthesis gas stream from the sorption apparatus and introduction into a plant for cryogenic gas fractionation 30.

[0060] The plant for cryogenic gas fractionation, which may be configured as a liquid methane scrubbing or as a partial condensation for example, effects separation of a synthesis gas product stream, for example an oxo gas stream, which via conduit 34 may be discharged from the process/the plant and sent for subsequent storage, treatment or further processing (not shown). The cryogenic gas fractionation further affords a hydrogen-enriched synthesis gas stream which is supplied via conduit 32 to a pressure swing adsorption plant 40.

[0061] The pressure swing adsorption plant effects resolution of the hydrogen-enriched synthesis gas stream into a pure hydrogen product stream which may be discharged from the pressure swing adsorption plant as a further product stream via conduit 42 and sent for subsequent storage, treatment or further processing (not shown). Also obtained is a residual gas stream which still comprises carbon monoxide and possibly methane, argon and further impurities. Said stream is discharged from the pressure swing adsorption plant via conduit 44 and may be sent for subsequent storage, treatment or further processing (not shown). Due to its heating value it is often utilized as a fuel gas stream and for example supplied to the synthesis gas production plant.

[0062] The disadvantage of the process shown in FIG. 1 is the use of the costly and high-complexity cryogenic fractionation process. Altering the composition of the synthesis gas product is possible only with difficulty and within narrow limits and necessitates deep interventions into the cryogenic gas fractionation.

[0063] In the block flow diagram shown in FIG. 2 according to a second example of the process/of the plant according to the prior art, conduit 11 passes the entirety of the raw synthesis gas produced for example using a synthesis gas production plant (not shown) which is configured as a steam reforming stage, as an autothermal reforming stage, as a partial oxidation stage or as a combination of at least two of the abovementioned synthesis gas production stages to a CO conversion plant 10 comprising at least one CO conversion stage and introduces it into said stage. This exemplary embodiment lacks a bypass past the CO conversion plant.

[0064] The CO conversion plant converts the crude synthesis gas stream under CO conversion conditions into a converted synthesis gas stream which is subsequently discharged from the CO conversion plant via conduit 14. Depending on the configuration and performance of the CO conversion, it is possible to achieve a complete or partial conversion of CO to H.sub.2 and CO.sub.2 and there are therefore certain adjustment possibilities for the H.sub.2/CO ratio to be achieved in the synthesis gas product.

[0065] The converted raw synthesis gas stream is introduced via conduit 14 into a sorption apparatus 20 for removal of acidic gas constituents, especially carbon dioxide and hydrogen sulfide, by means of a physical or chemical sorption process. This may be configured for example as a gas scrubbing with cryogenic methanol as the absorbent/scrubbing medium according to the Rectisol process known per se. Conduit 22 then effects discharging of a deacidified synthesis gas stream from the sorption apparatus and introduction into a pressure swing adsorption plant 40.

[0066] The pressure swing adsorption plant effects resolution of the hydrogen-enriched synthesis gas stream into a pure hydrogen product stream which may be discharged from the pressure swing adsorption plant as a product stream via conduit 42 and sent for subsequent storage, treatment or further processing (not shown). Also obtained is a synthesis gas product stream which is discharged from the pressure swing adsorption plant via conduit 44 and may be sent for subsequent storage, treatment or further processing (not shown). Due to its heating value it is often utilized as a fuel gas stream and for example supplied to the synthesis gas production plant.

[0067] The disadvantage of the process shown in FIG. 2 is that due to the low operating pressure of the PSA, the synthesis gas product, for example oxo gas, is obtained at low pressure and must be compressed for subsequent use. Furthermore, purity requirements for the synthesis gas product are often not achievable since it is obtained essentially as a waste product of the PSA and the cyclic operation of the PSA often leads to temporal fluctuations in the composition of the synthesis gas product. Finally, low availability of the synthesis gas product due to the combination of a PSA and a compressor is also a disadvantage.

[0068] In the block flow diagram shown in FIG. 3 according to a third example of the process/of the plant according to the prior art, a raw synthesis gas produced using a synthesis gas production plant (not shown), which is configured, for example, as a steam reforming stage, as an autothermal reforming stage, as a partial oxidation stage or as a combination of at least two of the abovementioned synthesis gas production stages, is divided into two proportions which are sent on via the conduits 11 and 13. Via conduit 11 the first proportion is passed to a CO conversion plant 10 comprising at least one CO conversion stage and introduced into said plant. The CO conversion plant converts the introduced proportion of the crude synthesis gas stream under CO conversion conditions into a converted synthesis gas stream which is subsequently discharged from the CO conversion plant via conduit 14 and introduced into a first sorption plant 20a. The remaining unconverted proportion of the raw synthesis gas stream is introduced via conduit 13 into a second sorption plant 20a.

[0069] The first and second sorption apparatuses 20a, 20b effect removal of acidic gas constituents, in particular carbon dioxide and hydrogen sulfide, using a physical or chemical sorption process. The sorption apparatuses may be configured for example as a gas scrubbing with cryogenic methanol as the absorbent/scrubbing medium according to the Rectisol process known per se. Conduit 22 then effects discharging of a converted, deacidified synthesis gas stream from the sorption apparatus 20a and introduction into a pressure swing adsorption plant 40. By contrast, an unconverted, deacidified synthesis gas stream is discharged from the process from the sorption apparatus 20b via conduit 23 and may be sent for subsequent storage, treatment or further processing (not shown), for example as oxo gas.

[0070] The pressure swing adsorption plant effects resolution of the converted, deacidified synthesis gas stream into a pure hydrogen product stream which may be discharged from the pressure swing adsorption plant as a further product stream via conduit 42 and sent for subsequent storage, treatment or further processing (not shown). Also obtained is a synthesis gas product stream which is discharged from the pressure swing adsorption plant via conduit 44 and may be sent for subsequent storage, treatment or further processing (not shown). Due to its heating value it is often utilized as a fuel gas stream and for example supplied to the synthesis gas production plant.

[0071] Disadvantages of the process shown in FIG. 3 are especially the specifically high capital costs for the treatment of the synthesis gas product stream, in particular for parallel operation of two sorption plants, and moreover in the case of coproduction of a small amount of the synthesis gas product in addition to large amounts of pure hydrogen. There is only limited flexibility to vary the product quantities and there is no direct option for influencing the H.sub.2/CO ratio in the synthesis gas product. Further disadvantages include the high complexity of the process chain and the considerable costs resulting from measures for ensuring a high availability of the synthesis gas product.

[0072] FIG. 4 now shows an exemplary embodiment of a process/a plant according to the invention for producing a synthesis gas product stream having an adjustable H.sub.2/CO ratio, especially an oxo gas, and a pure hydrogen stream. In the block flow diagram shown, conduit 11 passes a proportion 1 of a raw synthesis gas produced for example using a synthesis gas production plant (not shown), which is configured, for example, as a steam reforming stage, as an autothermal reforming stage, as a partial oxidation stage or as a combination of at least two of the abovementioned synthesis gas production stages, to a CO conversion plant 10 comprising at least one CO conversion stage and introduces it into said stage.

[0073] In addition to other considerations the configuration of the synthesis gas production plant should also be guided by the desired quantity ratio of the synthesis gas product stream and the pure hydrogen stream and by the desired H.sub.2/CO ratio of the synthesis gas product stream. When a large amount of a synthesis gas product to be employed as an oxo gas is required, noncatalytic partial oxidation is especially suitable on account of the produced raw synthesis gas having a high CO content.

[0074] The CO conversion plant converts the introduced proportion 1 of the crude synthesis gas stream under CO conversion conditions into a converted synthesis gas stream which is subsequently discharged from the CO conversion plant via conduit 14. The conduit 12 arranged as a bypass is used to run the remaining proportion of the raw synthesis gas past the CO conversion plant and directly into the conduit 14.

[0075] The mixed gas stream obtained from converted synthesis gas and unconverted raw synthesis gas is introduced via conduit 14 into a sorption apparatus 20 for removal of acidic gas constituents, especially carbon dioxide and hydrogen sulfide, by means of a physical or chemical sorption process. This may be configured for example as a gas scrubbing with cryogenic methanol as the absorbent/scrubbing medium according to the Rectisol process known per se. Conduit 22 then effects discharging of a deacidified synthesis gas stream from the sorption apparatus and introduction into a pressure swing adsorption plant 40. However, prior to this a proportion 2 of the deacidified synthesis gas stream is discharged via conduit 25 into a first hydrogen enrichment stage 50 containing a hydrogen-selective membrane as the separating means. The first hydrogen enrichment stage effects resolution of the deacidified synthesis gas stream into a hydrogen-enriched permeate stream which is discharged via conduit 52 and, jointly with the deacidified synthesis gas stream conducted in conduit 22, introduced into the pressure swing adsorption plant and into a hydrogen-depleted retentate stream which is discharged from the process via conduit 54 as a synthesis gas product stream and may be sent for subsequent storage, treatment or further processing (not shown). This synthesis gas product stream is especially sent to a subsequent plant for oxo synthesis (not shown).

[0076] The pressure swing adsorption plant effects resolution of the hydrogen-enriched synthesis gas stream into a pure hydrogen product stream which may be discharged from the pressure swing adsorption plant as a further product stream via conduit 42 and sent for subsequent storage, treatment or further processing (not shown). Also obtained is a residual gas stream which still comprises carbon monoxide and possibly methane, argon and further impurities. Said stream is discharged from the pressure swing adsorption plant via conduit 44 and may be sent for subsequent storage, treatment or further processing (not shown). Due to its heating value it is often utilized as a fuel gas stream and for example supplied to the synthesis gas production plant.

[0077] Establishment of the molar H.sub.2/CO ratio required for the synthesis gas product stream is made possible by appropriate selection of the proportion 1 and/or the proportion 2.

[0078] However, it is also possible to pass a proportion 3 of the carbon monoxide-containing residual gas stream into the synthesis gas product stream and to choose the proportion 1 and/or the proportion 2 and/or the proportion 3 such that the H.sub.2/CO ratio required for the synthesis gas product stream is obtained. This allows the composition of the synthesis gas product to be altered and adjusted finely and in targeted fashion, for example to produce an oxo gas having a predefined composition. This embodiment is advantageous especially when the residual gas stream comprises only a small proportion of impurities such as CO.sub.2, methane or argon. These impurities may optionally be removed using one or more purification stages (not shown) to ensure that the purity specifications for the oxo gas can be observed.

Numerical Examples

[0079] The table which follows summarizes the compositions of individual material streams and their total quantity flows and pressures for an inventive process/a corresponding plant according to FIG. 4.

[0080] In the present numerical example a raw synthesis gas stream of about 14 000 kmol/h having an H.sub.2 content of about 40 mol % and a CO content of about 52 mol % affords the following product streams: a pure hydrogen stream of about 9800 kmol/h having an H.sub.2 content of 99.9 mol %, an oxo gas stream of about 1000 kmol/h having an H.sub.2 content and a CO content of about 48 mol % each, a fuel gas stream of about 1900 kmol/h having an H.sub.2 content of about 74 mol % and a CO content of about 25 mol %.

[0081] While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

[0082] The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.

[0083] “Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.

[0084] “Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

[0085] Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

[0086] Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

LIST OF REFERENCE NUMERALS

[0087] [10] CO conversion plant [0088] [11]-[14] Conduit [0089] [20] Sorption apparatus [0090] [20a] Sorption apparatus [0091] [20b] Sorption apparatus [0092] [22]-[23] Conduit [0093] [25] Conduit [0094] [30] Plant for cryogenic gas fractionation [0095] [32] Conduit [0096] [34] Conduit [0097] [40] Pressure swing adsorption plant [0098] [42] Conduit [0099] [44] Conduit [0100] [46] Conduit [0101] [50] Membrane separation plant [0102] [52] Conduit [0103] [54] Conduit

TABLE-US-00002 TABLE Material streams and compositions for inventive exemplary embodiment according to FIG. 4 Conduit No. 11 14 22 + 25 25 54 52 22 22 + 52 44 42 From block No. PL 10 20 20 50 50 20 20 + 50 40 40 To block No. 10 20 40 50 PL 40 40 40 PL PL H2 mol % 39.9 92.7 91.8 91.8 48.2 98.5 91.8 95.6 73.7 99.9 CO mol % 51.9 5.0 7.7 7.7 48.2 1.5 7.7 4.1 25.2 <10 ppm CO2 mol % 5 34.6 <10 ppm <10 ppm <10 ppm <10 ppm <10 ppm <10 ppm <10 ppm 0.0 CH4 mol % 0.3 0.2 0.3 0.3 1.9 0.0 0.3 0.1 0.8 0.0 Remainder mol % 2.9 2.0 0.3 0.3 1.3 0.0 0.3 0.1 0.3 0.1 (N2, Ar) Total kmol/h 14012 20284 12791 7720 1023 6698 5070 11765 1928 9839 stream “dry” Pressure barg 54 50 48 48 46 20 48 48 0.5 47 PL = plant limits

Remarks:

[0104] Flow in conduit 42 (pure hydrogen): CO concentration <10 ppm according to pure hydrogen specification

[0105] Flows in conduits 22, 25, 44, 52, 54: CO.sub.2 concentration <10 ppm according to oxo gas specification