DE1231222B - Process for the production of synthesis gas for the production of ammonia - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

COIc

German class: 12 k-1/06

Number: 1231222

File number: M 62582IV a / 12 k

Filing date: September 26, 1964

Opening day: December 29, 1966

It is known that a mixture of hydrogen and nitrogen is used for the synthetic production of ammonia used, which should be free of sulfur compounds and carbon monoxide, because these compounds render the catalyst ineffective. This mixture should also be free of oxygen, because this with the Hydrogen forms water. Finally, the synthesis gas should contain as little inert gas as possible, because this accumulates in the cycle of the unconverted residual gas returned to the synthesis. With regard to nitrogen hydrogenation, inert gases are the noble gases and the median.

Synthesis gas for ammonia synthesis is mostly made solid or liquid through gasification Fuels produced with gasifying agents containing oxygen and water vapor, with initially a raw gas consisting mainly of carbon dioxide, carbon monoxide and hydrogen is generated that is then done by purifying and adding nitrogen to the appropriate composition is brought. The carbon monoxide content of these gases is catalytically converted with water vapor converted to carbon dioxide and hydrogen. Starting fuels are suitable for gasification or prepared hard coal or lignite, mineral oil fractions, especially high-boiling distillation and Crack residues and also refinery fumes.

It is known that the synthesis gas for ammonia synthesis, the nitrogen and hydrogen in the Ratio of 1: 3 should contain, by gasification of solid fuels or by splitting liquid or can produce gaseous hydrocarbons with so much air and water vapor that with Consideration of the hydrogen and oxygen contained in the fuel and that in the air Contained nitrogen a raw gas is created in which after conversion of the contained therein Carbon monoxide with water vapor to carbon dioxide and hydrogen this ratio of nitrogen to Hydrogen is achieved. However, the starting fuel is preferably made with technically pure oxygen and optionally water vapor converted into a carbon monoxide-rich gas in which the carbon monoxide is converted into hydrogen by conversion. The purified hydrogen pure nitrogen from the oxygen recovery system is then mixed in.

When cleaning the raw synthesis gas on the synthesis unit, carbon dioxide, hydrogen sulfide, organic sulfur compounds including carbon oxysuffide and that which is not converted during conversion Remove carbon monoxide.

Process for the production of synthesis gas for
the production of ammonia

Applicant:

Metallgesellschaft Aktiengesellschaft,

Frankfurt / M., Reuterweg 14

Named as inventor:
Dipl.-Ing. Hellmut Heidi,
Bad Homburg vd Höhe;
Dipl.-Ing. Reinhold Seipenbusch,
Dipl.-Ing. Ernst Kapp, Frankfurt / M.

From the gasification of coal or the splitting of liquid or gaseous hydrocarbons The raw gas produced is initially hydrogen sulfide and - if necessary - carbon dioxide washed out. For this purpose, the known, alkaline reacting regenerable absorption solutions, z. B. aqueous solutions of alkali salts of weak inorganic or organic acids are used will. Hydrogen sulfide and carbon dioxide can be used together or in one or more stages be washed separately.

The organic sulfur compounds absorbed by these solutions only to a small extent are converted catalytically to hydrogen sulfide, whereupon this is also removed from the gas is, for example with dry cleaning compound or with the above-mentioned liquid absorbents. These purification stages for the separation of the organic sulfur compounds can be omitted if one has the ability to convert carbon monoxide used with steam, e.g. B. iron oxides or molybdenum containing catalysts, organic sulfur compounds to hydrogen sulfide to hydrate, exploits. Since after the carbon monoxide conversion from the now hydrogen-rich gas already considerable amounts Carbon dioxide are washed out, this also becomes the result of the hydrogenation of the organic Hydrogen sulfide formed from sulfur compounds is washed out.

The unreacted carbon monoxide is then converted from the gas with an ammoniacal copper oxide solution washed out. Another way of removing the carbon monoxide from the syn-

609 749/356

3 4

thesegas consists in that the gas is at about -180 ° C. It is known, synthesis gases, which are predominantly washed off with liquid nitrogen. Carbon monoxide and hydrogen exist, in that when converting the carbon monoxide to the synthesis unit, the impurities such as carbon dioxide, iron oxides or molybdenum or tungsten and nickel 5 hydrogen sulphide, organic sulfur compounds or cobalt contained in the raw water vapor to form carbon dioxide and hydrogen in gas oxidic or sulphidic form and COS, resin-forming unsaturated and saturated holding catalysts at temperatures between hydrocarbons down to ethane together 350 and 450 ° C can have a residual concentration in the treated gas at pressures under pressure and at temperatures below 0 to about 30 at at carbon -80 ° C with suitable organic neutral solution monoxide of about 4 percent by volume. io washes out agents. Since the moisture content of the It is known that carbon monoxide with tempe gas when falling below 0 ⁰ C for ice formation ratures around 200 ° C leads to copper oxide catalysts, organic water-soluble solvents, steam to carbon dioxide and hydrogen, such as methanol or acetone, are preferred . This work can be carried out, with residual concentration in the gas but also being carried out in several stages, with carbon monoxide concentrations of less than 0.4 percent by volume in the second stage, hydrocarbons or mixtures being achievable. In view of the cheapness of the same can be used.
Equilibrium at the low reaction temperature It is known that hydrogen sulfide and carbon are not required to add a large amount of steam to the gas. On the other hand, that in the gas can be removed by saturation in the case of hydrocarbons. It is also known that at this temperature attainable vapor concentration 20 that toluene and xylene have a low selectivity for sulfur. This way of working will therefore preferably have hydrogen over carbon dioxide. Up to now it has been noted for gases with a low initial concentration that xylene is used for carbon oxy-carbon monoxide. The catalysts sulphide the better absorption coefficient compared to long an absolutely sulfur-free gas. Has hydrogen sulfide. This means that at full • It has been found that the production of constant scrubbing of the hydrogen sulfide can simplify all synthesis gas for the ammonia synthesis, essentially other sulfur compounds including COS, if the conversion of the xylene is taken up. Other physika raw gas containing carbon monoxide with water-lish absorbent with the same property vapor to carbon dioxide and hydrogen in two have so far neither in the literature nor in experimental steps, whereby the main amount of the 30 part was determined first.

Carbon monoxide is formed from iron oxide or molybdenum. It has been found that a physical gas retardant Catalysts at 350 to 400 ° C up to washing with xylene at temperatures from -10 to a residual concentration of about 5 percent by volume -20 ° C, preferably -15 ° C, and at 30 ata is implemented and this residual concentration pressure gives the gas purity, which is required, by further conversion of a copper oxide to the conversion of the carbon monoxide to water catalyst up to less than 0.4 percent by volume of material in a direct series connection is reduced. from hot conversion and cold conversion

This residual CO content can be supplied by hydrogenation.

be converted into methane, which in this low Da for the fine gas purification according to the invention with Amount does not interfere with the ammonia synthesis, as long as the 40 xylene content is a refrigeration machine before the conversion In terms of total inert gases, which is already present in the ammonia, it is expedient to also use the synthesis gas at most 1.2 percent by volume are washing of the carbon dioxide from the converted should not be exceeded. Gas at temperatures below -15 ° C with xylene

That made from the synthesis gas after the carbon monoxide.

45 It has been found that this CO _{a is} free of sulphate and can be used for the production of urea leaching with xylene is gaining in importance as a basic chemical material. and also of argon very considerably diminished. This pure carbon dioxide can also be found in life. In the low-temperature decomposition of the air for medium-sized industries, z. B. for the production of dry ice, 50 production of the pure nitrogen and the found as VerVergabe and fulfills when blowing into the gassing agent serving oxygen, the atmosphere remains the industrial hygiene regulation, no argon for oxygen and thus appears to contain an-sulfur compounds. enriched component in the hydrogen-rich order to the process known per se for the conversion of gas after the conversion when the leaching of the carbon monoxide with steam to 55 of the carbon dioxide by means of the known aqueous, oxidic or sulfidic catalysts is carried out with approximately alkaline absorption solutions. 400 ° C and directly on copper oxide catalysts.It is a particular advantage of xylene that the raw gas required to be able to be connected in series, the absorption of carbon dioxide must already be completely sulfur-free and, in particular, a large amount of detergent that is not purified from organic sulfur compounds. The proportion of the gas that is omitted from hydrogen is considerable, so that no amounts of sulfur can be absorbed in the hot conversion. About hydrogen is reproduced from the CO. The complete desulphurisation of synthesis gases with chemically absorbed 9%> of CH ₄ approx. 26% and of argon approx. 7%. Since the carbon monoxide into methane finally kenden absorbents requires multistage systems with is converted, this means a reduction in one step, in which the organic sulfur 65 of the inert gas content of around 40 ° / _0th The solubility of the compounds completely excreted or hydrogenated by argon in xylene has improved by almost 2 powers of ten. The last stage is in any case a higher one than in aqueous solvents. This results in effective sulfur refinement. the possibility of the traces still contained in the gas

COS .... .. 0.03 Volume percentage CH ₄ .... .. 0.2 Volume percentage N ₂ .. 0.4 Volume percentage Ar .. 0.4 Volume percentage 400 Nm ³ Zh

5 6

of about 0.2 percent by volume of CO through catalytic hydrogenation to methane, with the last traces of CO _{2 also} being recorded.

The inventive method for production
of ammonia synthesis gas flows through gasification 5
liquid or solid fuels containing oxygen
Gases and steam, cleaning of the raw gas
and catalytic conversion of its carbon dioxide The 100,000 Nm ³ / h of this gas are made of hydrogen and carbon dioxide, which 34,500 kg / h vacuum residue oil is washed out with a sulfur compound, mixing the water content of 3 percent by weight by gasification with substance-rich Gas with nitrogen and subsequent 26,000 Nm ^{3 of} oxygen and 141 high-pressure steam with compression consists in that after 1600 ⁰ C generated from the raw gas. The gas is cooled by direct cooling of the usual separation of condensable substances with water with the separation of soot and, finally, water vapor, the sulfur compounds in sizable constituents and occurs under a known manner at -10 to -20 ° C with xylene full pressure of 30 ata and are ^{constantly washed out with +35 0} C in the gas cleaning, then the treated one. Mixed for subsequent desulfurization through a gas with steam and heated to about 350 ⁰ C Xylolwäsche at -15 ° C the gas in a heat heated exchanger initially in a known manner to a brown indirectly sulfur-free with cold gas is oxydkatalysator at temperatures of 400 ⁰ C and cooled and at the same time sprinkled with cold methanol on a copper of the substances at 200 to 220 ° C to prevent ice after renewed addition of water vapor in a manner which also condenses and for easier separation. Oxide catalyst then takes place except for a CO content of approximately the leaching of H ₂ S and COS by means of xylene is converted to 0.4 percent by volume, so that now with reference to A b b. 2 explained annex,
more hydrogen-rich gas the CO ₂ in known

Way by washing with xylene at about _{-15 ° C to a 5} ^The desulphurized gas (98 200 Nm ³ / h) has the

collect with proportions of CO, CH ₄ and argon from the following analysis:

is washed, and that the CO ₂ 3.8 percent by volume is then consumed in the gas

remaining CO hydrogenated to methane in a known manner ^, ~ . _n ~ _ΛΤ ,

is, whereupon the CO-free gas by adding ^{C0 49} ' ^{3 volume percent}

pure N ₂ to an H ₂ : N ₂ ratio of 3: 1 one-30 H ₂ 45.9 percent by volume

and put to the pressure of the NH ₃ synthesis _{CH 0 2} percent by volume

is sealed.

This for plant and operating costs of a plant ^N a 0.4 percent by volume

for the production of ammonia synthesis gas very difficult Ar 0.4 percent by volume 396 Nm ³ / h

eight advantages are based on the one hand on the 35

unused property of xylene, carbon. The H ₂ S and COS content of the gas is lower

Oxysulphide dissolves better than hydrogen sulphide, and al 1 ppm. The absolute argon content of the gas is

on the other hand, reduced by means of xylene except by 4 Nm ³ / h.

Carbon dioxide also significant amounts of the inert gas. This gas is washed out in the direct and indirect heat gas component, namely methane and argon. 40 exchange with hot water and with the partial from this in turn results in the possibility of a converted gas ^{heated to about 350 0} C and saturated with hot conversion and a cold conversion of the water vapor and then passed into the first stage of carbon monoxide directly in series with CO conversion.

and the small carbon monoxide residues due to a pressure of 28.8 ata and a temperature

multiple methanation to be able to render harmless 45 rature from 350 to 420 ⁰ C is here in a z. B. with

nen. Brown oxide catalyst filled reactor of the CO

On the basis of the figures, let the content of the gas according to the invention go from 49 to about 5 percent by volume

Procedure explained in more detail: reduced.

A b b. 1 is the flow diagram of the invention. This gas is after cooling in the indirect Process with the hourly mass 50 heat exchange with the sulfur-free, in the con amounts as well as the respective pressures and temperature control entering gas by injecting ratures; Water to the temperature of the second conversion

A b b. 2 is the flow diagram of the desulphurisation stage, around 200 to 220 ° C, and at the same time again

plant before conversion; saturated with water vapor.

Fig. 3 is the flow diagram of the converter on the 55 At this point between the two converters The subsequent xylene wash to the greatest possible extent can result in a partial washout of carbon dioxide separation of carbon dioxide and the partial elimination take place in such a way that a partial flow of the gas is scrubbed of methane and argon, cools, passed through a pressurized water wash and

is then added to the main stream again. These

τλ T? r η u ™ t, + _1mmnM s / ur ^ ^6o measure can be useful to the texture

f «Sun« 7i , ϊϋΓΑ ,, ηΐ 'of ^{the gas after the first} * conversion stage to the

the following composition. _{Activity of the copper oxide catalyst of the second}

Adjust level.

^c ° 2 ⁴ > ² percent by volume I _{n of the} second stage of the CO conversion

CO 48.87 percent by volume 65 at a pressure of 27.8 ata and at a temperature

_u / ic ο Λ7- 1 ^{of e} ^ ^wa 220 ⁰ C in a with copper oxide catalyst

^H 2 ⁴⁵ ' ² percent by volume of the reactor filled the CO content of the gas of 5

H ₈ S 0.7 percent by volume reduced by about 0.4 percent by volume. After the con-

7 8

carbon monoxide is about 118,000 when 1 ppm COS and H ₂ S) is washed. The heat ^{of absorption occurring at Nm 3} / h with the following composition: the absorption heat

by indirect heat exchange of the gas and

CO ₂ 35.3 percent by volume of the detergent with your in the evaporator 7 one

CO ... 04 volume percent ⁵ refrigerating machine evaporating ammonia discharged.

H ₂ '.'. '.'. '.'. '. 63,464 volume percent? ^The scrubbed sulfur-free gas flows in the

* - .. ,,,,.,. Line 8 through the heat exchanger 2 and flows

^CH * 0.166 percent by volume with + 25 ⁰ C to CO conversion.

N ₂ 0.34 percent by volume The laden xylene running off from the washing tower 6

Ar 0.33 percent by volume 396 Nm ³ / h io is heated in the heat exchanger 9 and into the

Regeneration column 10 passed. The heating of the

This gas is in a plant according to A b b. 3 Column 10 takes place in the heater 11 by heating steam, washed with xylene at -15 ° C and 26.8 ata, whereby the regeneration is carried out at 2 ata and in the case of a sump in addition to the carbon dioxide also considerable proportions of about 165 ° C,
of methane, carbon dioxide and argon with 15 The expelled gas scrubbing _{rich in H 2} S and COS. Then the amount of gas mixture is about 1800 Nm ³ / h, leaving the return ^{about 75 820 Nm s} / h. The gas then has the following condenser 12 through line 13. It contains approximately the following composition: 38 percent by volume H ₂ S and is for extraction

rr> η ι Λ / ν ^ π ™ bitten · /, ™ «+ elemental sulfur in a Claus furnace.

^ w ₂ u, ± ν oiumproicnL. . ·, · -, τ · ± - *

20 The regenerated detergent is m the line 14

^{CU U} ' ^b6 volume percent _{through the} heat exchanger 9 and through the NH ₃ -

H ₂ 98.02 volume percent vaporizer 15 out and gets deep-frozen on the

CH ₄ 0.198 volume percent washing tower 6. By the methanol injection in the

N ₂ 0.512 percent by volume of heat exchanger 2 gets methanol vapors into

Ar '.'. '.'. '.'. '. 0.48 percent by volume 368 Nm ³ / h ² S the detergent circuit of the xylene wash. To the

To keep the methanol content of the xylene at about 2 ° / _0,

In the configuration of the xylene wash, a branch stream of detergent is then passed through line 16,

Taken care that no xylene vapors in pure form - which contains xylene, methanol and some water,

gas remain. for separation by distillation in the distillation column 17

The residues still remaining in the gas then passed to 30. The column 17 is heated in

CO and CO ₂ are at 25.5 ata and 250 ° C on a heater 18 indirectly by heating steam. At about

Nickel-containing catalyst to methane about 1.5 ata and at a sump temperature of about

sets so that the gas before the compression following + 150 ° C are methanol, water and a portion

Composition has: xylene blown overhead, in the condenser 19

35 liquid and in the container 20, which acts as a separator

H _{2 is formed} 98.11 percent by volume, collected. That in the container through

CH ₄ 0.88 percent by volume of xylene separated by volume

N ₂ o, 52 percent by volume the line 21 in the washing circuit to the washing

Ar o'49 volume percent tower 6 returned. The methanol-water mixture

40 is transferred from the container 20 through the line 22

The amount of gas is about 74 150 Nm ³ / h. The inert gas content, mainly as reflux to the column 17, CH ₄ and Ar, is 1.37 percent by volume. given, partly together with the Me-Da the _{nitrogen-water mixture required for the NH 3} synthesis from the heat exchanger 2, about 23 850 Nm ³ / h, still small amounts of acid through the line 23 and may contain the steam-heated precursor, which must be kept away from the synthesis 45 heater 24 in an indirect by means of the heater 26, the nitrogen is expediently already passed to the steam-heated column 25. 1.5 ata the gas admixed prior to the methanation, it and is reacted at a bottom temperature of about +110 ⁰ C the oxygen to water. In the the methanol is distilled off from the water, ^{liquefied in the compression of the mixture (about 98,000 Nm 3} / h) on condenser 27, collected in container 28 about 325 ata takes place in the usual way and partly through line 29 as reflux drying by condensation. The inert gas content returned to column 25, partly through line 3 of the compressed synthesis gas, is finally returned to heat exchanger 2. From just 1.04 percent by volume. The bottom of the column 25 flows over the cooler 30 and

The desulfurization of the raw gas takes place in the line 31 from water.

Annex according to A b b. 2. The leaching of carbon dioxide from the inflowing gas (100,000 Nm ³ / h) ^{in gas line 1 55 is saturated with water vapor at + 35 0} C and gas after the conversion of carbon monoxide 30 ata. It is carried out in the annex according to A b b. 3. The gas heat exchanger 2 sprinkled with methanol (about 118,000 Nm ³ / h) passes through the line 32 with the heat-washed gas cooled to -15 ° C. by indirect heat exchange with the cold at a pressure of about 26.8 ata in the heat-washed gas. 60 by the exchanger 33 and is in this indirectly by injecting methanol from the line 3, the cold purified gas is cooled to about -15 ⁰ C and prevents the formation of ice in the heat exchanger. 2 The methanol-water mixture, which is simultaneously sprinkled with methanol from line 34, is passed in line 4 to separate out the water vapor content and perform a distillative separation. To prevent ice formation. The cooled gas flows The gas cooled to -15 ° C then flows through the 65 into the scrubbing tower 35, in which the CO ₂ line 5 enters the scrubbing tower 6, in which it is at 26 ata and up to 0.1 percent by volume with about 1250 m ³ / h xylene -15 ° C and 125m ³ / h of technical grade xylene to by Ca for at -15 ⁰ C and about 26 ata from the gas CO conversion required purity (wash is less, at the same time in addition to the carbon

Dioxyd also shares of methane, argon and CO are absorbed. The detergent is a commercially available mixture of m-xylene and o-xylene and contains about 2 percent by weight of methanol. The refrigeration requirement for cooling the gas from −15 ° C. to the lower temperature of approximately −25 ° C. at the head of the washing tower 35 and all the cold _{losses are covered in the NH 3} evaporator 36 of a refrigerating machine. This is for the desulphurisation system according to A b b. 2 and for the car wash according to A b b. 3 jointly provided and is expediently designed as an absorption refrigeration system, which is operated with the waste heat from the converted gas. The CO ₂ -free gas is fed through line 62 to the synthesis plant. The loaded detergent flows through the line 37 into the first stage of an expansion system 38 consisting of turbines and pumps. Here, the detergent is expanded to about 9 ata with the release of energy. The detergent is then degassed in the lower part of the expansion tower 39 at about 9 ata and -16 ° C. In line 40 the expansion gas flows into an exhaust pipe 46. The detergent, which has been expanded to 9 ata, flows through line 41 into the second stage of the unit 38. Here the detergent is relaxed to about 2 ata with further energy release. The detergent arrives through the conduit 42 to the upper part of the flash tower 39 and is degassed at about 1.4 ata and -25 ⁰ C. _{A very pure CO 2} (approx. 35,000 Nm ⁸ / h), which can be used to generate urinary storr, is produced as a relaxation gas through line 43. The detergent relaxed to 1.4 ata flows through the siphon 44 into the middle part of the expansion tower 39 and is degassed in this at 1.3 ata and -26 ° C. by blowing out (stripping) with cold dry air. The stripping gas flows through line 45 and a heat exchanger 54 into exhaust line 46.

To blow out the detergent in the middle section of the tower 39, about 16,000 Nm ³ / h of air are required. This air is sucked in through the line 47, compressed to about 1.6 ata by the fan 48 and cooled to about -35 ° C. in the cooler 49. The air is further cooled in the heat exchanger 50 and in the cooling tower 51. To avoid ice formation in the heat exchanger 50, methanol is injected from the line 52. In the cooling tower 51, the air is cooled directly to -18 ° C. by sprinkling with a cold methanol-water mixture. The methanol-water mixture circulating in line 53 through the cooling tower is cooled indirectly in heat exchanger 54 by cold stripping gas. Some water is constantly introduced into the cooling tower 51 by the strip air. In order to limit the water content in the circulating coolant to a maximum of 5 percent by weight, a partial flow is withdrawn through line 55 and collected in line 58 together with the methanol-water mixture from lines 56 and 57. This methanol-water mixture is worked up together with the methanol-water mixture obtained in the desulfurization system in the distillation column 25 (A b b. 2). The distilled methanol returns to the plant through line 59. The gas cooled in the presence of methanol in the heat exchanger 33 entrains small amounts of methanol and water into the scrubbing tower 35. In order to maintain a methanol content of about 2 percent by weight in the detergent, a corresponding substream is constantly branched off from the washing circuit in line 60 and passed into the common distillation column 17 (Fig. 2) in the two washing plants. The xylene freed from methanol and water

.5 returns through line 61 to the second gas scrubbing system.

The investment costs and the resource requirements of the method according to the invention are compared to the conventional process considerably smaller.

ίο Another advantage of the method according to the invention results from the inert gas balance between raw gas and synthesis gas, with both the sulfur compounds before the conversion of the carbon monoxide as well as the carbon dioxide and parts of the Inerts can be washed out with xylene at -15 ° C after the carbon monoxide has been converted.

CH ₁ argon 20th
There are included
in the raw gas
in the desulphurized gas
and after the conversion
²⁵ tation
in the clean gas 200Nm ³ / h
196Nm ³ / h
150 Nm ³ / h 400Nm ³ / h
396 Nm ³ / h
358 Nm ³ / h Reduction of the inerts 25% 8 ° / o

In the second Xylolwäsche of the remaining carbon monoxide about 9 ° / ₀ washed and the methanation be withdrawn. Since 1 mole of carbon monoxide 1 mole of methane yields of inert gas for about 40 ° / ₀ is detected by the Xylolwäsche.

Claims (3)

Patent claims: 1.' Process for the production of ammonia synthesis gas by gasifying solid or liquid fuels with oxygen and water vapor, cleaning the raw gas, catalytic conversion of the carbon monoxide contained in the gas with water vapor to carbon dioxide and hydrogen, washing out the carbon dioxide, mixing the now hydrogen-rich gas with nitrogen in a ratio of N ₂ : 3 H ₂ and compression of the mixture to the pressure of ammonia synthesis, characterized in that the sulfur compounds are completely washed out of the raw gas after the usual separation of condensable substances including water vapor in a known manner at -10 to -20 ° C with xylene that the sulfur-free gas is heated to about 350 ° C and mixed with steam to convert the carbon monoxide contained therein is passed through two immediately successive catalyst stages, the first of which is operated in a known manner with a catalyst effective at temperatures around 400 ° C d, the second, after renewed addition of steam, also works in a manner known per se at 200 to 220 ° C with a copper oxide catalyst that is washed out of the gas in a known manner by means of xylene at temperatures below -15 ° C, the carbon dioxide together with the proportions of methane and argon and that the gas to remove the last traces of carbon 609 749/356 monoxide and carbon dioxide in a known manner via a methane-forming nickel catalyst is passed at 200 to 220 ° C. 2. The method according to claim 1, characterized in that the nitrogen is the hydrogen-rich Gas is added before methanation. 3. The method according to claim 1, characterized in that between the two stages for Conversion of the carbon monoxide into hydrogen from a partial flow of the gas by means of a known per se pressurized water washing, the carbon dioxide formed is washed out. 1 sheet of drawings 609 749/356 12.66 © Bundesdruckerei Berlin