DE1272280B - Process for producing NH synthesis gas from hydrogen-containing gas mixtures - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

German class:

Number:
File number:
Registration date:
Display day:

COIc

F25j

12 k -1/06

17 g-2/01

P 12 72 280.4-41 (G 37327)

March 21, 1963

July 11, 1968

The invention relates to a method for producing NHg synthesis gas by regenerative Separation of hydrogen and methane-containing gas mixtures under pressure, the gas mixture in at least one of at least three cyclically exchangeable regenerators for separating condensable Components is so deeply cooled that the bulk of the methane condenses and one Raw hydrogen fraction remains, which is practically all of the hydrogen in the raw gas, however only Contains small amounts of methane, after which the separated condensates are re-evaporated and the raw hydrogen fraction performing work after appropriate heating for the purpose of cooling relaxed and then in a regenerator that has been mainly freed from condensates is warmed to room temperature.

For the production of hydrogen-containing gas mixtures, their hydrogen later for the ammonia synthesis is used, there are several options. For example, arise through gasification solid or liquid fuels or through the oxidative conversion of hydrocarbons and a subsequent conversion of the carbon dioxide gas mixture, which, in addition to hydrogen, a lot of CO. ,, contain more or less nitrogen and still considerable residues of methane, carbon dioxide, etc.

Even when performing these procedural steps, additional measures are sometimes necessary, in order to remove any sulfur compounds that could damage contact, especially organic compounds. In a multitude of steps, each of which has a different working methodology, apparatus and monitoring requires, the cleaning of the converting gas then takes place until it is ready for synthesis Mixture.

It is known _{to remove the CO 2} in physical or chemical scrubbing, which is followed by the even greater effort of a copper lye scrubbing or catalytic methanation for the removal of small amounts of CO, which then remain as methane in the synthesis gas.

In parallel to this, there is also the process of decomposing coke oven gas by means of pressure and cold for the production of synthesis hydrogen. This also requires a previous careful removal of the carbon dioxide and any sulfur compounds. However, it then removes all impurities such as CH ₄ , CO and oxygen from the gas in one operation and, after scrubbing with liquid nitrogen, delivers the purest synthesis gas. This type of production of synthesis gas from coke oven gas, in processes for producing
NH ₃ synthesis gas from hydrogen-containing
Gas mixtures

Applicant:

Linde Aktiengesellschaft,

6200 Wiesbaden, Hildastr. 2-10

Named as inventor:

Dr.-Ing. Ernst Karwat, 8000 Munich-Pullach

The heat exchange takes place in tube countercurrents, however, is due to higher gas and system costs and a higher energy consumption compared to the modern process of producing Synthesis gas from convert gas disadvantaged.

On the other hand, the scrubbing with liquid nitrogen, which brings about the excellent purity of the synthesis gas, is also used to purify converting gas. However, such a system is heavily burdened by the high costs of the necessary preceding CO _{2 scrubbing.}

The object of the present invention is to purify converting gas or other hydrogen-containing gases Gas mixtures, such as coke oven gas, and their subsequent conversion into ready-to-synthesize To simplify hydrogen-nitrogen mixtures and a source of gas that is so diverse for the decomposition such as coke oven gas or nitrogen-containing convert gases to create unchanged applicable processes.

The invention is based on a method proposed by the inventor in which Compressed gas mixtures containing hydrogen and methane in a system with at least three cyclically exchangeable regenerators are dismantled, the gas mixture in at least one of at least three cyclically changeable regenerators for the separation of condensable components so deep is cooled so that most of the methane condenses and a raw hydrogen fraction remains, which contains practically all of the hydrogen in the raw gas, but only small amounts of methane contains, after which the separated condensates are re-evaporated and the raw hydrogen fraction after appropriate heating for the purpose of cooling, relaxed and relaxed while performing work

809 569/5 «

then in a regenerator that has mainly been freed from condensates to room temperature is heated.

The object is achieved according to the invention in that the raw hydrogen undergoes a subsequent purification is subjected by washing with liquid nitrogen that the heating before the relaxation of the Raw hydrogen takes place through heat exchange with pressurized nitrogen and thus the nitrogen scrubbing

branched off a partial flow from him, warmed up and then reunited with the main flow, so that, from starting from the increased mixing temperature, the expansion of the raw hydrogen without the formation of condensate runs. The final temperature of relaxation is a few degrees below that temperature with which the raw hydrogen exits from the first regenerator.

The heating of the raw hydrogen before his

Required cold is supplied and that the re-io relaxation with the help of the branched off partial flow Evaporation of the deposited in the regenerator works even when the nitrogen scrubbing

Condensate fraction completed by passing a gaseous carbon oxide-nitrogen mixture over it which is taken from the bottom of the nitrogen washing column.

According to a special embodiment of the inventive concept, part of the gas mixture to be processed can be subjected to partial oxidation with O ₂ or H ₂ O to form a mixture of mainly H ₂ , CO and CO ₂ and the reaction product

not yet working, so that after a standstill the regenerator system is cold on its own can be driven. The warm additional hydrogen can also be taken from the already warmed up to room temperature and raw hydrogen re-compressed to synthesis gas pressure can be diverted, but is sometimes required nor the removal of any traces of water vapor and carbon dioxide that may have been carried along.

An essential feature of the new way of working

High-pressure compressor for 80 to 200 atü, compression to, for example, 13 ata, the pressure of the

N ₂ -WaSdIe.

after its conversion with the unchanged is that the refrigeration for the regenerator part the hydrogen and methane-containing gas system with the refrigeration for the nitrogen mixture mixed laundry is linked before the regenerative decomposition. The preparation of the synthesis gases is considerably simplified if a

To carry out the method according to the invention, a regenerator system consisting of precompressed, precooled and then liquefied from three cyclically exchangeable regenerators is used as a detergent, each of which is used in terms of time So behind- nitrogen is transferred and so the loss of cold that each other does those work steps that are covered during the nitrogen scrubbing system. Then each switching period in the three regenerators 30 eliminates the high pressure that is otherwise common in such systems. This regenerator nitrogen cycle, and instead of the expensive multi-stage system, also includes an expansion turbine.
Further essential parts for carrying out the method according to the invention are a nitrogen washing column and a plurality of heating elements
exchange. Is a nitrogen scrubbing final stage of the
Purification of hydrogen from its accompanying substances,
then the synthesized gas produced must not be used under any circumstances
become contaminated during heating. The raw hydrogen is therefore warmed to room temperature, if necessary after the work step, the process of preliminary expansion, in the regenerator plant differs from all previously known sales, and then in the opposite direction to the decomposition of coke oven gas: from class flow to nitrogen-hydrogen Mixture is cooled again in tubular niches with exchangers working in tubular countercurrents, before it is driven to the washing column, in that the constituents are conducted in the latter. The advantage of the coke oven gas as C ₃ , C ₂ , methane and CO is deliberately omitted, the cold raw hydrogen is formed separately from the cold fraction in the course of freezing at the end of a regenerator directly from the washing column and usually also obtained separately ; and to supply, although after separating from those processes in which coke oven gas in coke oven gas already has the low temperature, the pure regenerators are cooled by the fact that with these means and has the pressure with which it usually ends the cooling is when ethylene and carbon nitrogen scrubbing is added. dioxide together with a small part of the methane

This rule can be deviated from in so far as the evaporated bottom product of the nitrogen washing column is heated in a regenerator and to compensate for the heat equivalent amount Hydrogen instead of going through the regenerators directly to the

If NH ₃ synthesis gas is to be produced from coke oven gas according to the method of the present invention, then in the first regenerator the vast majority of the methane contained in the coke oven gas (85 to 95%) is separated out. With this

Washing column is performed.

So that the raw hydrogen when it is heated in the third regenerator is actually used by everyone To clean residues of non-evaporated condensate, it is advisable to close it beforehand for the purpose of cooling relax and thus increase the volume with which it is heated by this regenerator goes out. The raw hydrogen to be expanded is

are condensed. Only outside the regenerator is a CH ₄ fraction formed there with further cooling.

The re-evaporation of the condensates will now be discussed using the example of the processing of coke oven gas. The processing of hydrogen mixtures other than coke oven gas using the new process is described later. Apart from the fact that instead of 60 methane and nitrogen then mainly CO ₂ and

Nitrogen are by-products of hydrogen, all work processes are so similar that the Re-evaporation of the condensates using the example of coke oven gas processing with general applicability

holds after its ab- 65 can be explained in the first regenerator, separation from the hydrogen-rich gas mixture At the end of the loading period of the first rain

still condensable accompanying substances such as CH ₄ , CO and rators or before the evaporation of the deposited N ₂ , but no CO ₂ . Before the expansion is made from condensates, the regenerator contains in addition to that

Condensate still contains a considerable amount of gaseous hydrogen, which, however, must not go into the residual gas together with the condensate, but has to be combined with the raw hydrogen. For this purpose, before the start of re- _{evaporation of the condensate, the H 2} content of the second regenerator is expanded via its cold end into the raw hydrogen flowing through the third regenerator. The remaining hydrogen in the second regenerator can be fed via the cold end of the regenerator to a pair of auxiliary generators, heated in them and fed to a compressor, which compresses it to operating pressure and mixes it with the coke oven gas to be broken down. The alternating pair of auxiliary regenerators is supplied with compressed coke oven gas to compensate for heat, where it is broken down into raw hydrogen and condensate, the latter being returned to the coke gas stream from the relaxed hydrogen residue in the next switching period.

A shut-off valve is now opened at the warm end of the second regenerator, which has been completely depleted of its hydrogen content. First of all, those condensates which, like CH ₄ , have been deposited at a higher pressure than atmospheric pressure escape, and condensates located in higher temperature regions sublime, such as CO ₂ or H ₂ O.

The re-evaporation of all condensates is facilitated if the pressure above the condensates is reduced, i.e. if they are suctioned off at a pressure lower than 1 ata, and / or if an auxiliary gas is fed from the outside via the cold end via the condensates to the warm end. Evaporated CO-N ₂ mixture, which is obtained as a liquid at the bottom of the N ₂ washing column, is ideally suited. If more than 2% of the raw gas amount of this mixture is to be passed through the regenerators instead of through the heat exchangers of the nitrogen scrubbing, an equal amount of hydrogen must be fed directly to the scrubbing column instead of being heated in the regenerators. This of course presupposes that the pressure in the nitrogen scrubber and the pressure in the regenerator system are appropriately coordinated, and also does not affect more than 10 to 15% of the total amount of H ₂ produced.

A significant advantage of the process according to the invention can be seen in the fact that the same process and the same apparatus as in the processing of coke oven gas can also be used to obtain the synthesis hydrogen from converting gases from their generation from fuel and air and the subsequent conversion It contains little methane, but still contains N _{2 in} addition to a lot of carbon dioxide, namely nitrogen in at least the amount necessary to sublimate the carbon dioxide. This necessary amount is available when the vaporized gases such as N ₂ , CO and CH ₄ coming from the cold end of the second regenerator occupy a greater effective volume in their pressure-temperature state when subliming the CO _{2 than the accompanying gases H 2} , N ₂ , CO etc. in their pressure-temperature state when the CO _{2 is} condensed. In practice, the ratio of the two effective volumes should be greater than 1.1, while to compensate for this, an equivalent amount of raw hydrogen is not fed in the regenerator, but cold to the washing column.

This removal of the sublimation gas from the washing column sump is appropriate for the converting gases, which are very poor in N ₂ , etc., because they are generated with oxygen or water vapor. A disruptive shortage of sublimation gas can be countered by adding air to the oxygen or water vapor or of flue gas to the converting gas.

The purity and treatment of the raw hydrogen by letting down the pressure, warming up and washing with liquid N ₂ is the same as described above.

It is a great advantage of the process of the invention that the same apparatus and method of operation can be used _{to remove large amounts of nitrogen in addition to CO 2} , such as are present in converting gases that have been generated with air. This has achieved the long-sought goal of making NH ₃ synthesis particularly cheap types of gas, such as air-containing mine gas, blast furnace top gas, products of dust gasification, fluidized bed gasification, generator gas from ash-rich fuels, etc., accessible. Gasification and conversion are preferably carried out under pressure, but also at such a low pressure that the sublimation of the CO _{2 is} ensured in the regenerators and the cooling requirement can be met.

The oxygen that _{arises in the N 2} production is about a third of the total requirement for synthesis gas generation. The gasification air is expediently enriched with it. As with all other forms of application of the method of the invention, the raw gas can be cooled to the temperature corresponding to _{the H 2 purity of 90%.}

With the amount of nitrogen to be condensed in the regenerator, the weight of the regenerator filling increases and so does the pressure drop in the regenerator. The heating surfaces can be cheaper if the nitrogen excretion is partially transferred to the countercurrent heat exchanger of the N _{2 scrubbing and if sufficient N 2 is} still excreted in the regenerator for the CO ₂ sublimation.

The usability of the new process is not yet exhausted. There are e.g. B. in the production of synthesis gas from coke oven gas several problems that make a modification of the process described above desirable. One such problem is a lack of available coke oven gas for the production of a certain amount of synthesis gas. This problem is old and has hitherto been solved in such a way that the methane contained in the raw gas or separated from it by freezing is oxidatively converted into CO and H _{2 with O 2} or H ₂ O, and the CO is converted with steam to H ₂ and CO ₂ , the CO _{2 was} washed out and then the hydrogen was finely purified, e.g. B. by methanation of CO or by freezing and washing with liquid nitrogen. Before deep freezing, the carbon dioxide is removed from the gas stream with a pressurized water wash and a subsequent wash with caustic or in a low-temperature wash with methanol or in a potash wash.

In dealing with this problem according to the method of the invention, two partial flows are fed to the regenerator system, the first being a mixture of H ₂ and hydrocarbons, the second being a mixture of H ₂ with CO ₂ and N ₂ . The two partial flows are split up into two fractions in the regenerators by means of pressure and cold, one of which, gaseous, practically represents the

contains all of the hydrogen from the two substreams in addition to residues of CH ₄ , CO and N ₂ , while the other fraction, which is deposited as condensate on the storage mass, contains practically all of the other components of the two substreams. These fractions are treated further in the manner already described.

Mixtures of H ₂ with hydrocarbons, as they are used alone or as the first substream to run the

The elimination of a special facility for CO ₂ removal is the most important effect of combining both partial flows in the regenerator.

An advantage of combining two partial flows, 5 each of which supplies a different type of condensate, is the more favorable distribution of the condensates in the regenerator. In the first partial flow, the low-boiling gases such as CH ₄ , CO and N ₂ predominate among the accompanying substances of the hydrogen and in the second

Process of the invention are used, if the partial stream is high-boiling, such as CO ₂ , the

z. B. coke oven gas, refinery gases, exhaust gases of the hy- regenerator over its length and over the temperature

Drier technology and products of the catalytic reforming field much more evenly with condensate formation

of gasoline, provided that it already pollutes as much water as the regenerators with one type of gas alone,

contain substance that its separation from the loading as if z. B. coke oven gas is applied,

lubricants due to pressure and cold in the regenerator 15 If only coke oven gas were processed in the regenerator,

is economical.

The second partial stream of H ₂ and CO ₂ can be obtained from the same type of gas from which the first partial stream is formed by oxidative conversion of the

90% of the condensates CH ₄ , N ₂ and CO were thus obtained near the cold end of the regenerator. If only H ₂ -CO ₂ mixture is processed, 90% of the CO _{2 would be} in the temperature range from 160 to

Hydrocarbons and conversion of the resulting 20 220 ° K accrue,

which CO is produced, but can also be applied to other

Way, e.g. B. by gasifying heavy fuel oil with accordingly the quantitative ratio of the partial flows both

Oxygen and subsequent conversion formed the warm zone for condensing CO ₂ as well

will. Hard coal, lignite, gasoline or natural gas are the cold zones for condensing CH ₄ .

can be starting fuels and used as 25. The different levels of heat of vaporization

gassing agents can be used in addition to or instead of CH ₄ and CO ₂ corresponds to the difference in

Oxygen also air or water vapor are used to specific heat of the storage mass in the two

the. Of course, with an H ₂ -CO ₂ mixture, the temperature ranges. To obtain the same H ₂ -

Process of the invention can also be carried out alone. Quantities may be used by the regenerators for the process.

the, if there is only enough N ₂ for the sublimation 30 rensweise of the added substreams mostly something

of the CO ₂ contains. be smaller than the regenerators for the process

To cover the costs of generating the H ₂ -CO, -stream wisely without substreams. But they get just as big

to keep it low, larger quantities may not be made in it, which only costs some storage mass, like that

decomposed hydrocarbons remain, the system may, depending on the market situation for raw gas, residual

after the conversion with steam, a large gas, heating oil and coal, for both processes

rer remainder of CO remain in the gas, because both usable.

Excess CH ₄ as well as CO are in the regeneration. Working with two different partial flows

rator or in the subsequent wash with liquid gives much greater freedom in the selection of raw materials

According to nitrogen, very substances for gas generation with practically no additional effort.

40

completely secluded.

When the nitrogen is produced from the air for the N ₂ scrubbing, an equivalent amount of oxygen is produced. It is economically advantageous to generate the second substream with oxygen and

the amount of the second partial flow of this existing 45 fits or can be regulated. Adjust the amount of oxygen. The invention is based on the

Is used for the oxidative conversion of fuel systematically shown device on several Beibeim Production of the second partial stream water vapor play described, used and the heat required for this through consumption. ·, <

burning of residual gas is supplied, so the after 50 example!

The amount of heat to be given off outside is reduced and sales difficulties for the residual gas are met.

When working with two partial flows, the
Re-evaporation of the CO ₂ -Kondensats according to the invention consisting of the first part stream at lower tempera- 55 makes Each regenerator consecutively deposited dieperaturgebieten gas components CH _4, jenigen steps that used during a switching-CO and N _2. Surprisingly, the re-evaporation of the CO ₂ succeeds in the three regenerators next to each other, especially when it is running: 53000Nm ³ coke oven gas with 60% H ₂ if it is still supported by negative pressure and purging gas which is increased to a pressure of 10 kg / cm ² in the compressor 4, exceptionally completely . In spite of this, compressed, via line 5 into the regenerator 1, the raw hydrogen reaches the raw hydrogen when it is fed into the and cooled there. The most condensed switching period flows over the storage mass of the convertible components, including the largest identical regenerator, and individual volume parts of the methane on the storage mass lower CO ₂ per million, and a look-up is required. The substance leaving the regenerator 1 with heat treatment when this raw water temperature of about 83 ° K is cooled again via line 6 before the N ₂ wash. The favoring of the raw hydrogen contains about 90% H ₂ , 0.6% CH ₄ , re-evaporation of the CO ₂ by means of lower 4% CO, 5.3% N ₂ , 0.1% O ₂ . A partial flow of CH ₄ or N ₂ and about 2% coming from temperature regions is passed through line 7 and valve 8

The usability of the residual gas makes a significant contribution if, according to the invention, with the quantity ratio, in which the partial flows are fed to the regenerator, the burning properties - calorific value and density of the gas - desired values

Decomposition of coke oven gas (H ₂ hydrocarbon

Mixture)

1, 2 and 3 are three cyclically exchangeable regenerators as cold storage and heat exchangers.

branched off, warmed in a coil 9 and reunited via line 10 with the main stream brought in line 12 after the latter has cooled compressed nitrogen in heat exchanger 11 and warmed up in the process. The raw hydrogen is expanded in the turbine 13 to about 3 kg / cm ² pressure and enters the regenerator via the line 14, where it is heated to the usual temperature.

At the beginning of this flushing period, the raw hydrogen still absorbs the hydrogen, which escapes from the previously loaded regenerator 2 when the valve 15 is opened until the pressure in this has dropped from 10 to 3 ata. During this period of time, the regenerator 3 is freed from the condensate residues that were left in the previous period of re-evaporation. Such a period of re-evaporation takes place in the regenerator 2 during the switching period described. With the initial pressure of 3 kg / cm ² , the regenerator 2 is emptied via the lines 16 and 17, ie via the warm end. Components that were condensed at higher pressure, such as CH _{4 in} addition to a residue of hydrogen, flow off at overpressure and evaporate ethylene in the process; Ethane, carbon dioxide, water, etc. Finally, the fan 18 lowers the pressure in the regenerator to 0.5 kg / cm ² . The evaporation, especially of the methane at the cold end, is significantly promoted by the fact that a CO-N ₂ mixture originating from the bottom of the washing column 19 is transferred via line 20 to heat exchanger 21, in which it evaporates, and from there via line 22 is fed to the regenerator 2, is relaxed in this from the cold end of the regenerator. The raw hydrogen leaving the regenerator 3 through the line 23 - laden with condensate residues is compressed in the compressor 24 to the pressure of the nitrogen scrubber, via the line 25 to the heat exchanger 26 and from there the line 27 is fed to the heat exchanger 21 and cooled to low temperature. The rolling hydrogen enters the nitrogen washing column 19 through the lines 28 and 30 and the separator 29, with liquid nitrogen flowing in from above through the line 36. This is compressed in the compressor 31 to the pressure of the nitrogen scrubber before entering the washing column; fed via line 32 to the heat exchanger 33, there in countercurrent to the bottom product of the washing column evaporated in the heat exchanger 21 and a part of the pure H ₂ -N ₂ mixture and cooled via line 34 to the _; Heat exchanger 11 and from there the heat exchangers 21 and 3 $ fed, where the nitrogen is further cooled. Line 36 connects the last two heat exchangers to washing column 19. At the top of this washing column, a synthesized H ₂ -N ₂ mixture is drawn off via line 41, which is heated partly in heat exchanger 26, partly via line 42, and warmed up in heat exchanger 33 and can be taken from line 43. Traces of water and carbon dioxide are removed from the raw hydrogen with adsorbers. Methane is for the most part already separated from the raw hydrogen in the exchanger 21 and in the separator 29 before it enters the scrubbing column, so that the CO-N ₂ mixture obtained in the bottom of the scrubbing column 19 is sufficiently poor in methane to still be in the regenerator 2 to be able to evaporate solid CH _4. From the separator 29, the liquid methane passes via line 37 into the heat exchanger 35, where it is evaporated and from where it is evaporated through line 38 together with the evaporated CO-N ₂ mixture coming from heat exchanger 21 via line 39 through the heat exchanger 33 and through line 40 to the residual gas line 17 is performed. The function of washing with liquid N ₂ is the usual one. The plant produces 40 700 Nm ^{3 of} mixture of 75% H ₂ , 25% N ₂ and ^{23,500 Nm 3 of} rich gas with an upper calorific value of 6800 kcal / Nm ³ per hour. 160 · 10 ^e kcal are for sale. The energy consumption for the The provision of the synthesis gas is only 75% of the energy consumption in a classic plant.

Example 2

A converting gas is produced with 27.7% CO ₂ , 38.5% H ₂ , 3% CO, 2% CH by gasifying flame charcoal at 6 ata with an air-oxygen mixture with 28% O _{2 and reacting with water vapor 4} , 29.4% N ₂ . ^{16,500 Nm 3 of} raw hydrogen 91% H ₂ , 3% CO, 5.5% N ₂ , 0.6% CH _{4 are} branched off from 40 800 Nm ³ convert gas at 5.5 ata pressure in the regenerator system, after appropriate preheating in the pipe coil 9 or im- heat exchanger 11 in the turbine 13 to 1.4 ata relaxed, heated in the regenerator 3, then compressed in the compressor 24 to 13 ata and after renewed cooling in the heat exchangers 26 and 21 by washing with liquid nitrogen in the washing column 19 converted into synthesis mixture H ₂ + N ₂ . The CO-N ₂ mixture occurring in the washing column sump is evaporated and heated in countercurrent to the raw hydrogen and pure nitrogen in the heat exchanger 21 and the residual gas is added, which by evaporation of 11350Nm ³ CO ₂ with 500 CH ₄ , 500 CO and -750 H / -und 11 3QONm ³ N _{2 is created} in the regenerator 2! The gas stream of 29,500 Nm ³ H ₂ + N ₂ + CO + CH ₄ , of which 11,350 Nm ³ i-, CO _{a are} deposited when the regenerator is loaded, has an effective volume of 5.4 ata, of 5480 m ^s . When re-evaporation: stream 12,300 Nm ³ »N ₂ + CO + CH ₄ at a mean pressure of 0.75 ata over the CO ₂ condensate with an effective volume of 16,400 cm ³ (temperature influence both times not taken into account).

At the sublimation ratio '

4,6,400
5480

^; = ^r 3'tst the

Complete "evaporation dej" CO ₂ ensured. The energy consumption per ton of NET ₃ in this example is 10% higher than that in example 1. The price of the heat unit in hydrogen gas from flame coal is, however, a third lower than from stove gas and that is crucial for the synthesis price

; - Example 3

j A gas produced by gasifying fuel oil with oxygen and then converted contains 34.4% CO ₂ , 0.2% H ₂ S, 62.2% H ₂ , 3.2%; N ₂ + CH ₄ + CO.

For the purpose of more favorable sublimation of the CO ₂ in the regenerator, so much air was added to the oxygen that the content of N ₂ + CO + CH ₄ rises to 9%. If the mixture (32.4% CO ₂ , 0.2% H ₂ S, 58.4% H ₂ , 9% N ₂ + CO + CH ₄ ) is decomposed at 10 ata in the regenerator and the condensate at 0.5 ata re-evaporated, so is the sublimation ratio

809 569/543

I 272

the effective volumes during evaporation and condensation tripled compared to the sublimation ratio before the addition of air, i.e. cheaper. The greater the addition of air, the less CO ₂ goes with the raw _{hydrogen for N 2} scrubbing.

Examples 4 and 5

Further embodiments show how when using the same starting material, eg. B. coke oven gas, for three types of process, the amount of coke oven gas used and the amount, the calorific value and the density of the residual gas for sale can be varied within very wide limits can.

Example 1 related to the production of 30,000 Nm ³ H ₂ per hour (heat of combustion 3000 kcal / Nm ³ ) in a 40,000 Nm ³ H ₂ -N ₂ mixture from 53,000 Nm ^{3 of} coke oven gas (heat of combustion 4750 kcal / Nm ³ ) and 11,000 Nm ³ N ₂ . This resulted in an hourly total of 23,000 Nm ^{3 of} residual gas (heat of combustion 6800 kcal / Nm ³ ) from regenerators and nitrogen scrubbing.

Section A of the table shows these amounts of substance and their heat value, distributed 'over the starting material, Hydrogen and residual gas.

Example 4 (Section B of the table) relates in the production of 30,000 Nm ³ H ₂ according to Example 1 to the possibility of introducing 32 600 Nm ^{3 of} coke oven gas into the regenerators as the first substream and converting it to ^{16 350 Nm 3 of} _{converted H 2} - Mix in CO ₂ mixture, which was created by converting 8150 Nm ³ coke gas with 2040 Nm ³ O ₂ with the addition of 0.851 coke and 500 Nm ³ steam. The oxygen comes from the air separation plant in which the nitrogen for the synthesis mixture is obtained. The quantitative ratio of the two substreams was chosen so that the heat of combustion of the residual gas coming from the regenerators and the nitrogen scrubber is H ₀ = 5300 kcal and the gas density of the residual gas, based on air, is 0.72. Example5 (sections of the table) relates to the possibility of generating the second substream by oxidative conversion of 13700Nm ^s coke oven gas with water vapor at around 700 ° C and subsequent conversion of the CO to 25 260 Nm * H ₂ + CO ₂ , which then together with the first partial flow of 18,800 Nm ³ coke oven gas enter the regenerator system. Only 155 · 10 ^e kcal are added to the system, i.e. 100 · 10 "kcal less than in method A. 68 · 10 · ⁵ kcal remain in 14 260 Nm ³ residual gas, the density of which is so great that its burning properties are assessed from the Quotien TT

ten -j-, despite the calorific value of 4800 kcal, are not satisfactory.

For the regenerator rich gas fraction of 11090 Nm ³ with a heat of combustion of

So 5720 kcal and a molecular weight of 23.5 good burning properties are to be expected. Therefore, the CO-N ₂ fraction is not combined with the rich gas, but _{consumed separately to cover the heat demand of the CH 4} conversion. Only for the 27.2 kcal

The regenerator rich gas fraction is used as the amount that is still missing. For sale are 41 · 10 ⁶ kcal in 7150 Nm ³ rich gas fraction with 5.72 · 10 ³ kcal / Nm ³ with the desired burning properties.

^{The comparison with the 160 · 10 e} kcal with 6800 kcal / Nm ³ for sale in the process without partial streams shows that the possibility of selling very large amounts of high calorific value gas is essential for the economic viability of process example 1, while the partial stream processes are in place there are where only calorific value gas has a market. The partial flow formation is not limited to the use of coke oven gas as the starting material.

Coke oven gas
Nm ¹ Deployed
Amount of heat
kcal hydrogen
Nm ¹ Useful
warmth
kcal Residual gas eir
(CO + N ₂ i finally
)-Fraction
kcal / Nm ³ rest
warmth
kcal A.
B. First partial flow
Second partial stream
(H ₂ + CO ₂ 53000
32 600
8150
16350) 10 « 30000
18700
11300 10 « Nm * 10 ³ 10 » C. Coke oven gas
first partial flow
CH ₄ + H ₂ O
second partial flow 40750
18 800
13 700 252 30000
10 800
19200 90 23.5
14300
5050 6,800
1.127 160 32500 193 30000 90 19 350 5,300 155 90 8200
6060 6.8
2.0 103 14260
Effort ui
at Umw id losses
action 68.2
-27.2 7150 Nm ³ I. 41.0

Claims (2)

Patent claims: 1. A method for producing NH ₃ -SVnthesegas by regenerative decomposition of hydrogen- and methane-containing gas mixtures under pressure, the gas mixture being so deeply cooled in at least one of at least three cyclically changeable regenerators for separating condensable components that the bulk of the methane condenses and a raw hydrogen fraction remains, which is practical contains all of the hydrogen in the raw gas, but only small amounts of methane, after which the separated condensates are re-evaporated and the raw hydrogen fraction after appropriate weaning for the purpose of cooling, relaxed and then doing work in a regenerator that has mainly been freed from condensates to room temperature is heated, characterized in that that the raw hydrogen of a post-purification by washing with liquid nitrogen is subjected to the heating of the raw hydrogen before it is released Heat exchange with pressurized nitrogen takes place and IO so that the necessary cold is supplied to the nitrogen scrubbing and that the re-evaporation the condensate fraction separated in the regenerator by passing a gaseous carbon oxide-nitrogen mixture over it is completed, which is taken from the bottom of the nitrogen wash column. 2. The method according to claim 1, characterized in that part of the gas mixture is subjected to partial oxidation with O ₂ or H ₂ O to a mixture of mainly H ₂ , CO and CO ₂ and the reaction product after its conversion with the unchanged part of the hydrogen - and methane-containing gas mixture is mixed before the regenerative decomposition. 1 sheet of drawings 809 569/543 7.68 © Bundesdruckerei Berlin