DD155516A1 - METHOD FOR OBTAINING HYDROGEN AND OTHER DISPOSAL PRODUCTS - Google Patents

Abstract

The process for recovering hydrogen and other decomposition products is used in the operation of methanol synthesis plants to increase the performance characteristics of the forced expansion gases. The qualities of the products obtained by cryogenic treatment should be suitable for use in chemical syntheses, which is achieved according to the invention in that the methanol synthesis plant, a physical laundry, an adsorption device and apparatuses and machines for cryogenic treatment of the cycle exhaust gas are combined. High hydrogen yields are achieved with optimal energy consumption.

Description

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VEB Leuna-Werke Leuna, 20.11.1980

"Walter Ulbricht"

LP 80113 Title of the invention

Process for the control of hydrogen and other decomposition products

Field of application of the invention

The process can be used in the chemical industry in the operation of methanol synthesis plants for the purpose of increasing the performance characteristics of the flash gases inevitably resulting from the methanol synthesis. It is possible to use the invention both in newly installed and existing methanol synthesis plants apply ·

Characteristic of the known technical solutions

It is generally known that the ammonia is first removed from the purge gases obtained in the synthesis of ammonia and consisting of hydrogen, nitrogen, argon, methane and ammonia, and the hydrogen is separated from the components of the sest. The coverage of the cold losses of the separation process

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carried out without (air and refrigeration Jj> (1980) 1, pp. 15 to 19) or with (The oil and gas journal - March j> (1979) p. 182) supply of external refrigeration.

Furthermore, it is generally known to use the residual gas fraction obtained in the hydrogen recovery technology for obtaining further decomposition products, such as argon and methane (Ind. Eng. Chem. Process Des. Develop Jj., 3 (1973), p. 217 bio 220). ,

These processes have the disadvantage that they can not be used in the recovery of hydrogen and, if appropriate, further decomposition products from the expansion gases of the methanol synthesis, since completely different components are contained in the purge gases of the ammonia synthesis in completely different concentrations than in the expansion gases of the methanol synthesis, v Moist particularly from hydrogen, nitrogen, carbon monoxide, argon, methane, carbon dioxide, methanol, higher alcohols, Dinetbyläther u · a, trace impurities exist. Here, the methods that work with the supply of external refrigeration, the further disadvantage of a relatively high energy consumption, operating and investing expenses ·

It is also known that for the separation of gas-steam mixtures, the mixture is cooled in a heat exchanger under pressure and no external cooling takes place at any point in the process, the mixture is expanded to a separator to a lower pressure and after the separator both The process is, inter alia, for the separation of hydrogen from hydrogen-rich gas mixtures applicable (DD-PS 47 120). However, it has the disadvantage that it is not applicable if the lower boiling component contains more than 70 % of hydrogen in the gas mixture and the pressure of the gas mixture is only moderately high. Moreover, it is of particular disadvantage that it is made for the extraction of hydrogen

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the expansion gases of methanol synthesis iat not applicable, because the higher-boiling substances contained in the expansion gases, such as carbon dioxide, methanol, higher alcohols, dimethyl ether u, a · impurities condense or freeze during the cooling of the gas mixture in the apparatus and thus a stable continuous operation at low Temperatures are not possible ·

Finally, it is known to separate a gas mixture containing at least two components with greatly varying volatility by partial condensation under pressure by the gas mixture is cooled to a temperature at which the higher boiling de (n) component (s) substantially as condensate and in the the lower boiling component (s) are present in the desired purity and that in order to cover the refrigeration budget, a work-performing expansion of the gaseous separated component, mixture of this component with a portion of the recovered condensate, evaporation, heating and recycling of the mixture in the gas mixture ( DD-PS 84 031).

The method has the disadvantage that it is applicable only to gas mixtures in which no sublimation cryogenic treatment components are contained ·

Object of the invention

The aim of the invention is to work up the expansion gases obtained forcibly when methanol synthesis is carried out to a higher use value.

* Presentation of the essence of the invention

It was therefore the task of the components hydrogen and other decomposition products by cryogenic treatment to win from the resulting in methanol synthesis flash gases · The qualities of the hydrogen and other decomposition products largely for use

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The object of the invention is to eliminate the deficiencies and imperfections of the known processes for hydrogen production, especially if the hydrogen-rich gas mixtures contain impurities which freeze during the cryogenic treatment and if relatively high hydrogen concentrations and only moderately high pressures are present ·

Thus, the recovery of hydrogen peroxide and other components from the purge gases of the ammonia synthesis by means of low temperatures necessitates the arrangement of a water scrubber, a drying plant and heat exchangers so that the purge gases from the purge gases, first the ammonia, due to the thermodynamic properties of the components washed out, then the purge gases are dried and separated after their cooling by partial condensation and, if necessary, rectification into their components o

Since the thermodynamic properties of the components contained in the continuous cycle exhaust gas of the methanol synthesis are partly similar and sometimes completely different from those of the components of the purge gases, the recovery of hydrogen and other decomposition products from the recirculation exhaust gas of the methanol synthesis requires the combination of other devices and also other process steps. which can not be derived from the solutions known in the purge gas decomposition «

The process for the separation of gas-vapor mixtures is suitable for separating components with very different thermodynamic properties, in particular with very different boiling points. The separation energy and the cooling losses are thereby covered from the potential energy by throttling the gas mixture or its decomposition products to be separated The parameters of the recirculating exhaust gas obtained in the ethanol ethanol synthesis are essentially dependent on the fuel used

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Synthesis of synthesis gas, the technology of synthesis and the preparation of the components hydrogen, carbon monoxide and carbon dioxide required for synthesis. They are generally between 70 and 85 % hydrogen and about 7 MPa and thus significantly worse at least at the border It requires the procedure for a safe coverage of the separation energy and the cold losses.

Finally, the process of disassembling a gas mixture requires that there are no contaminants in the gas which freeze out during the whole process. In the Kreislaufentspannungsgasen the methanol synthesis, however, with the components of carbon dioxide, methanol, dimethyl ether, higher alcohols u. a. Trace impurities such interfering components present · For the cryogenic treatment of such a gas there are no instructions for technical action

Features of the invention

The object is achieved by a method for recovering hydrogen and other decomposition products from flash gases by cooling, cryogenic treatment under pressure, relaxation, partial condensation and optionally rectification, reheating the recovered fractions and their forwarding for further use, the cold household of the plant with or without supply is covered by external refrigeration from an external refrigeration system, according to the invention achieved in that as expansion gas forcibly obtained in a methanol synthesis plant Kreislaufentspannungsgas, which essentially the components hydrogen, nitrogen, carbon monoxide, argon, Kethan, carbon dioxide, methanol, dimethyl ether, higher hydrocarbons u Contains trace impurities, is used and the methanol synthesis plant, a physical wash, an adsorption as well as apparatuses and machines for cryogenic treatment of the cycle exhaust gas miteinad he combined. In this case, the circulation release gas

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This is preferably the majority of the carbon dioxide contained in the flash gases washed out, recovered during the regeneration process from the Y / ash liquid by relaxation and heating and withdrawn for further use · Thereafter, the freed from carbon dioxide Kreislaufentspannungsgas initiated in a reciprocally operated adsorption and thereby the remaining Kengen carbon dioxide and the amounts still contained methanol, dimethyl ether, higher hydrocarbons, inter alia · Finally, the recirculation exhaust gas is further cooled in heat exchange with the fractions obtained under pressure and passed partially condensed in a cryogenic separator, it is without supply of external energy in a gaseous Wassoffoff fraction and a liquid Reatgasfraktion separated The recovered gaseous hydrogen The recovered fraction of liquid residual gas, which still consists of hydrogen, nitrogen, carbon monoxide, argon and methane, is expanded and either also in heat exchange with the recirculating exhaust gas again heated and withdrawn for further use or supplied to a further Tiefftemperaturabacheidung and there in a hydrogen and carbon monoxide enriched fraction and a methane-enriched Abgasf The fractions obtained in this way are reheated in the heat exchange with the recirculating expansion gas and withdrawn for further use. The cooling losses of the overall process are compensated by throttling relaxation and / or by working expansion of the Kreislaufentspannungsgasea and / or a recovered fraction and / or by supplying cold from an external refrigeration system.

Due to the inventively made combination of the methanol synthesis plant u. a. with the physical wash

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it is advantageous if the physical washing of the cycle exhaust gas under pressure * by means of methanol at a reduced temperature, preferably at about 213 K to 233 K, is made.

It has been shown that it is then particularly favorable for the removal and recovery of the carbon dioxide contained in the recirculation exhaust gas, when the recirculation exhaust gas and the methanol are cooled and passed under pressure into a scrubbing tower and there!,! Ethanol led in countercurrent to the recirculation release gas becomes. In this case, the washing liquid loads with the carbon dioxide contained in the Kreislaufentspannungsgas. The loaded methanol is heated again to about Nornaltemperatur or above and relaxed in a carbon dioxide. As a result, the carbon dioxide is released and can be withdrawn in gaseous form from the carbon dioxide separator for further use. The liquid deposited in the separator methanol is brought back to increased pressure and recycled in the circuit after its cooling to the physical washing process. The purified in this way Zreislaufentspannungsgas is withdrawn under pressure and at low temperature for further treatment of the scrubbing tower.

On the carbon dioxide and the circulation method of Methanoles can be omitted if the methanol obtained in the methanol synthesis plant is used as a washing liquid. In this Pail, the relaxed and reheated, loaded with carbon dioxide methanol is passed into the existing due to the technology of methanol production methanol separator and the released carbon dioxide is removed together with the product expansion gas of the methanol synthesis from the methanol separator for further use.

The production of the methanol synthesis plant can be increased if the carbon dioxide-enriched product expansion gas withdrawn from the methanol separator satisfies the syn-

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thesegas for methanol synthesis is added «

For the removal of the residual contaminants contained in the recirculation release gas, such as carbon dioxide, methanol, methyl ether and Dirnethyläther. a. Trace impurities which would interfere with the cryogenic treatment of the cycle exhaust gas, it has proved to be advantageous to use a reciprocating adsorption means using silica gel and / or molecular sieves.

It has proven to be particularly advantageous if the alternately operated adsorption under pressure and at low temperature, preferably at temperatures between 213 and 233 K, operated and the regeneration of the adsorbent by heating preferably to temperatures of about 430 K to 650 K takes place.

High hydrogen yields with optimum energy consumption can be obtained by operating the cryogenic separator under a pressure of about 4 l.IPa or at the pressure of the recirculating exhaust gas present and the gaseous hydrogen fraction present in the cryogenic separator without the addition of external energy under almost the same pressure withdraws further use.

For the purpose of securing the refrigeration budget of the overall process, as well as the achievement of favorable quality and Energiekenn'ziffern, it has proved to be advantageous in the Teiftemperaturabscheider recovered residual gas fraction to a low pressure, preferably to a pressure between 0.12 and 0.35 i .IPa to relax and regulate the amount of this fraction so that due to the Wasserst offgehaltes the partial pressure of the residual components is above their melting point. If the residual gas fraction continues to be used to obtain a fraction enriched in Y / oxygen and carbon monoxide and enriched with methane, it is particularly advantageous to supply the residual gas fraction to a second cryogenic separator and to supply it without supply of external energy at a pressure between 0.12 and

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0.25 I IPa to operate. The Lie ng en the withdrawn from the second Tiefteniperaturabscheider fraction are then adjusted so that the enriched with hydrogen and carbon monoxide gaseous fraction at the head and the methane-enriched liquid fraction of exhaust gas at the bottom and due to the hydrogen content in the enriched methane exhaust fraction of the partial pressure the higher boiling components is above the melting point. Both recovered fractions are withdrawn from the second cryogenic separator after their heating for further use and it has been found that the flow control can also be carried out in such a way that a quantitative ratio of hydrogen to carbon monoxide in the enriched with hydrogen and carbon monoxide Fraction is formed with which this fraction can be fed into the synthesis gas for the synthesis of methanol, thus increasing the production of methanol.

If a recirculation vent gas of the methanol synthesis is used to produce hydrogen and other decomposition products whose volumetric content is more than 70 # and / or which is only under moderately high pressure, the refrigeration losses of the overall process can not be covered by throttle relaxation alone. For this case, it has been found to be particularly advantageous to compensate for the cooling losses of the overall process by throttle relaxation and / or by work-performing expansion of a portion of the enforced by the physical laundry Kreislaufentspannungsgasmenge. For this purpose, the work expanded relaxing Kreislaufentspannungsgas is heated either directly in the heat exchange to be cooled Kreislaufentspannungsgas and withdrawn for further use or the relaxed from the cryogenic separator liquid residual gas fraction or separated in the second cryogenic separator enriched with methane exhaust gas fraction and gas-vapor mixture in the heat exchange heated to the cooling cycle exhaust gas to be cooled and withdrawn for further use. The outlet temperature from the work-performing expansion device is only on the

- -IO -

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Adjusted temperature level at which the physical Y / ash of Kreislaufentspannungsgases made "or the recovery of the liquid residual gas or the methane-enriched waste gas fraction is performed.

To be particularly favorable, a temperature of about 208 or 80 li has proven to be the outlet temperature from the work-performing expansion device.

embodiments

The invention will be explained in more detail below with reference to 2 examples and the accompanying drawings v / ground.

Example 1 shows the scheme of a combination in which the carbon dioxide removal from the recycle vent gas is carried out by means of methanol at reduced temperatures. The recovered Y / acid fraction is removed under pressure from the overall process. The liquid residual gas fraction is re-heated in the / arm exchange with the expansion gases and withdrawn for further use. The cold budget of the process is covered by supply of cold, which is generated in an external refrigeration system operated by freons and by throttling the flash gas in the cryogenic separator and the liquid residual gas fraction.

Example 2 shows the scheme of a combination with a carbon dioxide removal according to Example 1. The recovered hydrogen fraction is withdrawn at nearly the same pressure from the overall process as the Sntsung gas is used. The liquid residual gas fraction is expanded into the second cryogenic soother and there obtained a enriched with hydrogen and carbon monoxide and a methane-enriched fraction. The cold household of the gas separation plant is due to work-relaxing a subset

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covered by carbon dioxide and other impurities "relaxation gas and by throttling incurred in the cryogenic separator liquid residual gas fraction.

The exemplary embodiments which illustrate the process according to the invention "describe the essential basic possibilities of obtaining hydrogen and other decomposition products from flash gases of the methanol synthesis." Moreover, within the process according to the invention, further combinations of the devices are available which derive from the respective technological and operational requirements.

For example, u. a.

- The technology described in Example 1 to cover the refrigeration budget are also replaced by work-related relaxation of a Teilnenge the Kreislaufentspannungsgases;

- The technology described in Example 1 and 2 to cover the refrigeration budget are also replaced by a work-performing expansion of the hydrogen fraction obtained in the cryogenic separator.

example 1

1, synthesis gas, which consists essentially of the components Hp, N2, CO, Ar, CH- and COp, is known to be fed to a methanol synthesis ₂ through the line 1, the methanol formed being expanded through the line 3 into the methanol separator 4, the thereby separated crude methanol fed through the line 5 of the distillation 6 and withdrawn from this as pure methanol through the line 7. In order to avoid inert gas enrichment 2 Kreislaufentspannungsgas is withdrawn through the line 8 from the methanol synthesis. The product expansion gas released during expansion in the methanol separator 4 is withdrawn through the conduit 9. Cycle exhaust gas and product exhaust gas are generally burned.

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In this known technology, for example, 10.10 in (K) / h of cycle vent gas accumulates in line 8, which consists of approximately 81 # H ₂ , 5 # CO, 8 # CH ₄₅ 4 # CO ₂ , -0.3 0 CH ^ OH, 0.04 # H ₂ O, traces of dimethyl ether, amines and higher hydrocarbons open, balance N ₂ and Ar. It is at a pressure of about 7 IvIPa and a temperature of about 298 K the heat exchanger 10 au and there in countercurrent to the recovered products to about 253 Kabgekühlt. Through line 11, the cooled gas is passed into the scrubbing tower 12. This works at etv / a 233 KL and et v / a 7 LIPa. Here, a countercurrent treatment with cold Liethanöl as washing liquid, whereby preferably the CO _{2 is} washed out. The loaded with CO ₂ Liethanöl is withdrawn through the line from the scrubbing tower 12, the expansion valve 14 is relaxed there to about 0.2 LIPa, fed through the line 15 to the heat exchanger 16, there heated to at least 300 K and through the Line 17 fed into the CO ₉ separator 18. Here, the separation of the released in the relaxation and heating CO _{2 takes place} . About 0.4. 10 ⁵ m ⁵ (N) / h CO ₂ leave through the line 19 the CO ₂ separator 18 for further use. The C0 ₂ ~ free methanol is fed through the line 20 of the pump 21. This increases the pressure of the liquid methanol to about 7 LTa. The C0 _2- free ethanol is fed to the heat exchanger 16 through the line 22, where it is cooled in countercurrent to the CO ₂ -containing methanol and fed back to the scrubbing tower 12 'through the line 23 as washing liquid. The amounts of methanol condensed out of the recirculating exhaust gas in the process are supplied from the pump 21 through the pipe 24 to the raw-methanol line 5. At the same time an enrichment of the scrubbing tower is avoided with impurities. It is also possible to supply any existing methanol losses through the line 24 from the Rohhmethanolleitung 5 of the pump 21. In addition, it is possible to superimpose this methanol exchange a Methanoikreislauf au, with the line through the 24 additional amounts of methanol on the

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Pump 21, the line 22, the heat exchanger 16, the line 23 are supplied to the scrubbing tower 12 and are fed back from the line 20 via the line 24 of the Rohhmethanolleitung 5. This eliminates accumulation of impurities in the liquid methanol with certainty. To cover the refrigeration budget of the methanol wash liquid refrigerant is introduced from an external refrigeration system 25 through the line 26 into the cooling coil 27, there evaporated and fed through the line 28 of the external refrigeration system 25 again.

The only contaminated with traces of C0 _p and in particular with CH- * OH gas is withdrawn through line 29 from the scrubbing tower 12 and alternately fed via the lines 30.1 or 30.2 the alternately operated adsorbers 31.1 and 31.2. Here, at about 233 K and 7 HPa, the adsorption of the remaining impurities COp »CH, OH, dimethyl ether, amines and higher sols is open to molecular sieves.

By the lines 32.1 or 32.2 and the line 33 ver

3, about 9.5.10 m (N) / hr of purified recirculating exhaust gas leaves the adsorbers. They are fed to the heat exchanger 34, where they are cooled down to etv / a 90, partially condensed, fed through the line 35 to the Sntspannungsventil 36, there relaxed to about 4 LIPa and introduced through the line 37 into the cryogenic 38. Here, the separation takes place in a gaseous H ₂ fraction, which consists of about 7.3.10 ³ m ⁵ (N) / h H ₂ and 0.3.10 ⁵ m ³ (N) / h N ₂ , CO, Ar and CH ₄ and which is heated to about 295 K via line 39, heat exchanger 34, line 40, and heated to about 295 K and withdrawn through line 41 at about 4 MPa for further use. In the cryogenic 38 fall about 2.1O ⁵ m ⁵ (N) / h liquid residual gas fraction, consisting essentially of Hp, Np j CO, Ar and CH., On and are au by the line 42 the Sntspannungsventil 43 a, there to about 0th 2 LlPa relaxed, fed through line 44 to the heat exchanger 34, where the components N ₂ j CO, Ar and CHj evaporated under their partial pressure and heated by the line 45 to the heat exchanger 10, respectively. After heating, the residual gas fraction leaves the heat exchanger 10

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through line 46 with about 0.2 LIPa for further use.

Example 2

According to FIG. 2, 10.10 m (N) / * ¹ cycle release gas is produced in the same known ethanol ethanol as described in Example 1 in ethanol synthesis 2. They are passed through line 8 with a composition of about 81 % H ₂ , 5 # CO, 8 0 CH ₄ , 4 # CO ₂ , 0.3 # CH ₃ OH, 0.04 # H ₂ O, traces of dimethyl ether, Amines and higher hydrocarbons, remainder N ₂ and Ar at a pressure of about 4 LlPa and at a temperature of about 298 K supplied to the heat exchanger 10 where it is cooled to about 213 K and fed through line 11 to the scrubbing tower 12. The scrubbing tower operates at about 213 K and about 4 MPa. There, a countercurrent treatment with cold methanol as a washing liquid, wherein the COp is washed out of the Kreislaufentspannungsgas · The ethanol loaded with CO ₂ is withdrawn under pressure through the line 13 from the 7 / ash tower 12, the expansion valve 14 is fed, except for 0.2 LZPa relaxed, fed through the conduit 15 to the heat exchanger 16, there heated to at least 300 K and fed through the conduit 17 into the Methanolabsoheider 4. Here, the separation of the released during the relaxation and heating CO ₉ . About 0.4 × 10 m (N) / h of CO ₂ leave through the line 9 the methanol separator 4 together with the product obtained in the technology of the methanol synthesis reaction gas. It is the synthesis gas of line 1 mixed again. The amount of methanol required in the washing tower 12 is withdrawn from the line 5 as crude methanol and fed through the line 24 of the pump 21 duroh. This increases the pressure of the liquid methanol to about 4 MPa. Through the line 22, the liquid methanol is fed to the heat exchanger 16, where it is cooled to about 213 K and fed through the line 23 as washing liquid to the scrubbing tower 12. The only contaminated with traces of CO ₂ and in particular with methanol gas is withdrawn from the scrubbing tower 12 through the line 29 and alternately operated via the lines 30,1 or 30.2 the mutually operated

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Adsorbers 31.1 and 31.2 supplied. Here at etv / a 213 K and 4 MPa the adsorption of the remaining impurities CO ₂ , CE ₅ OH, dimethyl ether, amines and higher hydrocarbons to molecular sieves takes place. Through the lines 32.1 and 32.2

3 3

and the line 33 leave about 9.5.10 m (N) / h of purified cycle exhaust gas, the adsorber and the heat exchanger 34, respectively. Here is a further cooling of the Kreislaufentspannungsgases up to about 85 K. In this case, the Kreislaufentspannungsgas is partially condensed. Through line 35, it is introduced into the cryogenic separator 38. Here, the separation into a gaseous Hg fraction, which consists of about 96 % H ₂ and 4 ^ N ₂ , Ar and CH ₄ . It is fed via the line 39, the heat exchanger 34 and the line 40 to the heat exchanger 10 and heated to about 295 K. Through line 41, the Hp fraction is withdrawn at a pressure of about 4 MPa for further use »The obtained in the cryogenic separator liquid residual gas fraction consisting essentially of H ₂ , N ₂ , CO, Ar and CH. is passed through the line 42 to the expansion valve 43, there relaxed to a pressure of about 0.2 MPa, fed through the conduit 44 to the second cryogenic 47 and there in an enriched with E ₂ and CO fraction and one with CH. Enriched exhaust fraction separated. The enriched with H ₂ and CO fraction, which is still substantially N ₂ and Ar and relatively small amounts of CH. Contains as impurities is supplied through the conduit 48 to the heat exchanger 34, there heated, fed via the line 49 to the Y / exchanger 10, further heated there and zugemisoht after compression by the line 50 with about 295 K the synthesis gas of the line 1. The exhaust gas fraction enriched in CH, which still contains N ₂ , CO and Ar as contaminants, accumulated in the second cryogenic separator 47, is withdrawn through line 51. At the same time a portion of the freed from impurities Kreislaufentspannungsgases are withdrawn from the heat exchanger 34 through line 52 and fed to the work-performing expansion device 53. In doing so, a

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Cooling of the gas to about 80 K. The expanded gas is through, the lines 54 and 55 with the CH. enriched liquid waste gas fraction from the line 51 admixed. The mixture is fed through line 56 to heat exchanger 34, there the components Np ₅ CO, Ar and CH. evaporated under their partial pressure and heated through the conduit 51 introduced into the heat exchanger 10. Through line 58, this fraction is withdrawn at 295 K and 0.2 MPa for further use. The withdrawn through the line 52 amount of expansion gas is thereby regulated so that the Kreislaufentspannungsgas in the line 35 reaches a temperature of at least 85 K. To cover the cold losses of methanol scrubbing a portion of the work-relaxing relaxed Kreislaufentspannungsgases is withdrawn from the line 54, fed via the line 59 of the cooling coil 27, thereby heated and mixed through the line 60 of the line 51 .

Claims (12)

22 63 17 Claim for invention 1. A process for the recovery of hydrogen and other decomposition products from a flash gas by cooling, cryogenic treatment under pressure, relaxation, partial condensation and optionally rectification of the flash gas, reheating the recovered fractions and their forwarding for further use, the cold budget of the overall process with or without supply is covered by external refrigeration from an external refrigeration system, characterized in that contains as expansion gas forcibly obtained in a methanol synthesis plant Kreislaufentspannungsgas containing substantially the components of hydrogen, nitrogen, carbon monoxide, argon, methane, carbon dioxide, methanol, dimethyl ether, higher hydrocarbons and other trace impurities , is used and the methanol synthesis plant, a physical wash, an adsorption device and apparatuses and machines for cryogenic treatment of the cycle exhaust gas mitei nander combined by the Kreislaufentspannungsgas first cooled under pressure, fed to the physical V / äsehe, there washed out essentially the carbon dioxide and recovered from the washing liquid by relaxation and heating, then passed the freed from carbon dioxide Kreislaufentspannungsgas by the alternately operated adsorption , The remaining amounts of carbon dioxide and the amounts still contained methanol, dimethyl ether, higher hydrocarbons and other trace impurities are removed, finally the recirculation vent gas in the heat exchange to the obtained fractions further cooled under pressure and partially condensed introduced into a cryogenic temperature, thereby without supply of external energy in separated a gaseous hydrogen fraction and a liquid residual gas fraction, the recovered gaseous hydrogen fraction in the heat exchange to the Kreislaufentspannungsgas under pressure again he warms and for the further -ie- 226317 Withdrawn use, the recovered liquid residual gas fraction, which still consists of hydrogen, nitrogen, carbon monoxide, argon and methane, relaxed and either also heated in the heat exchange to the recirculation exhaust gas reheated and withdrawn for v / eiteren use or v / eiteren Cryogenic deposited and there in a fraction enriched with hydrogen and carbon monoxide as well as a methane-enriched waste gas fraction and this recovered fractions in heat exchange to the Kreislaufentspannungsgas v / re-heated and deducted for further use v / earth and wherein the cooling losses of the overall process by throttling relaxation and / or work-related relaxation of the Kreislaufentspannungsgases and / or .one of the obtained fractions and / or be compensated by supplying cold from an external refrigeration system. 2. The method according to item 1, characterized in that the physical scrubbing of the Kreislaufentspannungsgases by means of methanol under pressure at a lowered temperature, preferably at about 213 to 233 K occurs. 3. The method according to item 1 and 2, characterized in that for removing and recovering the carbon dioxide contained in the Kreislaufentspannungsgas the Kreislaufentspannungsgas and the methanol are passed with reduced temperature under pressure in a Y / ash tower, where the methanol is passed in countercurrent to the Kreislaufentspannungsgas wherein it is loaded with the carbon dioxide contained in the Kreislaufentspannungsgas, heated again to about normal temperature or above and expanded in a carbon dioxide, while the carbon dioxide is released and is withdrawn in gaseous form from the carbon dioxide for v / eiteren use, while liquid in the carbon dioxide separated methanol under pressure in the circulation after its cooling the physical WaschprozeI3 v / ieder fed and wherein the -19 - 22 63 17 Purified purge gas, pressurized and withdrawn from the scrubbing tower at low temperature for further treatment. Method according to items 1 to 3, characterized in that the methanol used in the methanol synthesis plant is used for the physical treatment and the methanol loaded with carbon dioxide is released into the methanol separator present on the basis of the methanol production technology the carbon dioxide released during the expansion is withdrawn from the methanol separator together with the product expansion gas of the methanol synthesis. 5. The method according to item 1 to 4, characterized in that the withdrawn from the methanol separator together with the product expansion gas of the methanol synthesis carbon dioxide is fed to the synthesis gas for the synthesis of methanol. 6. The method according to item 1 to 5, characterized in that the remaining amounts of carbon dioxide, methanol, Diinethylather, higher hydrocarbons and other trace impurities are removed by means of silica gel and / or molecular sieves from the Kreislaufentspannungsgas in the alternately operated adsorption. 7. The method according to item 1 to 6, characterized in that the alternately operated adsorption is operated under pressure, preferably at temperatures between 213 and 233 K, and the regeneration of the adsorbent by heating, preferably to temperatures of about 430 K to 650 K, he follows. 8. The method according to item 1 to 7, characterized in that the operated under pressure cryogenic separator operated at about 4 MPa or the existing pressure of the Kreislaufentspannungsgases and in the cryogenic separator -20- 226317 recovered hydrogen fraction is withdrawn after its warming under almost the same pressure for wider use. 9. Method according to item 1 to 7, characterized the liquid residual gas fraction obtained in the low-temperature separator is expanded to a slight overpressure, preferably to a pressure between 0.12 and 0.35 L ¹ Pa, and the amount of this fraction is adjusted so that the melting point of the higher-boiling components is not undershot. 10. The method according to item 1 to 9, characterized in that the further cryogenic separation takes place at a pressure between 0.12 and 0.25 1.IPa in a zv / eiten Cryogenic without external energy supply and the quantities d ^ r from the second Cryogenic fractions withdrawn fractions v / ground so that a hydrogenated and carbon monoxide enriched gaseous fraction at the head and a methane-enriched liquid waste gas fraction at the bottom of the second cryogenic separator is formed and the melting point of the higher-boiling components is not exceeded and these fractions after their heating for further use, optionally with the hydrogen and carbon monoxide enriched fraction is fed to the synthesis gas for the synthesis of methanol. 11. The method according to item 1 to 10, characterized in that the cooling losses of the overall process by throttling relaxation and / or work-performing expansion of a part of the enforced by the physical laundry Kreislaufentspannungsgasmenge v / earth, the work expanded relaxed Kreislaufentspannungsgas heated and withdrawn for further use or the relaxed from the cryogenic liquid residual gas fraction or the 2263 1 7 "separated in the second cryogenic separation, enriched with methane exhaust gas fraction and heated and withdrawn as a gas-vapor mixture, and the outlet temperature is regulated from the work-performing expansion device to the temperature level, carried out in the physical washing of the Kreislaufentspannungsgases or the recovery of liquid Restgasbzw , the exhaust fraction is carried out. 12. Terfahren according to item 1 to 11, characterized in that the outlet temperature is regulated from the work-performing expansion device to about 208 or about 80 K. This includes 2 sheets of drawing