NL8101433A - METHOD FOR CONVERTING CARBON AND / OR HEAVY PETROLEUM FRACTIONS IN HYDROGEN OR AMMONIA SYNTHESIS GAS. - Google Patents

Description

^ V · Λ

Br / Bl / lh / 22

Process for removing coal and / or heavy petroleum fractions in hydrogen or ammonia synthesis gas.

The invention relates to a process for removing coal and / or heavy petroleum fractions as starting material in hydrogen or an ammonia synthesis gas, so-called syngas, which mainly consists only of hydrogen and nitrogen.

The final step in the ammonia synthesis is the conversion of the finally obtained syngas of nitrogen and hydrogen / usually in the stoichiometric ratio of 1: 3, but sometimes also in another ratio, which is often accompanied by small amounts of impurities, in particular argon and methane, which conversion is carried out under high pressure using a catalyst, which in particular consists of iron and various promoters, for example the ammonia synthesis catalyst of the type AM, which is prepared and supplied by Haldor TopsjzSe A / S.

An example of the preparation of ammonia synthesis gas from natural gas and air has been described by H.F.A. Tops ^ e, H.F. Poulson and A. Nielsen in Chemical Engineering Progress, vol.63, no.10, 67.73 (October 1969}. A useful overview of aramonia technology can be found in the book "Ammonia" edited by AV Slack and G Russel James, Marcel Dekker Inc., New York and Basel 1977.

The need for ammonia, not least for fertilizers and starting materials for fertilizers, is increasing sharply. At the same time, the increasing energy scarcity and the extraction cost of natural gas have made it desirable to use other starting materials for the synthesis gas preparation as well as for hydrogen, ie either coal (such as coal, anthracite, lignite, peat and coke including petroleum coke} or heavy petroleum fractions, which are then gasified with the aid of oxygen and steam.When using carbon, the gasification reactions are as follows: 8101433 4 c + h2o x = ^ co + h2 (1) -2-- t C +% 02 - * co (2) where by-products can occur, such as metal and possibly other hydrocarbons and sulfur compounds, in particular hydrogen sulfide and carbonyl sulfide, which are formed from sulfur impurities of the coal, and possibly small amounts of nitrogen, argon and possibly tar materials.

The gasification of mineral oils is more complicated, partly due to the fact that, in particular, the heavy fractions consist of complex mixtures of higher paraffin, olefins and aromatics. An ideal example is the general reaction

CnHm + n / 2 ° 2 - * nC0 + m / 2 H2 (3) 15 but even, with partial oxidation of heavy hydrocarbons, thermal cracking occurs with the formation of free carbon:

CnHm --->; nC + m / 2 H2 (4) 20 In practice, both reactions (3) and (4) occur when oxygen is used, because in practice less than the stoichiometric amount of oxygen is used. Other possible reactions in the partial oxidation of mineral oils include: 25 CnHm + (n + m / 4) 02 hCC> 2 + m / 2 H20 (51 CH + nC0o s ~~ Λ 2ra CO + m / 2 H0 ( 6) nm 2 2 CH + m / 4 → nC + m / 2 H + 0 (7).

nm 2 2 and by the partial oxidation of liquid hydrocarbons with superheated steam: CH + nH-jQ nCO + (m / 2 + nl H9 (81 n iii a λ »and also as secondary reactions reaction (1) and C + CO2) 2C0 (91

Since a normal burn in the gasification reactor is insufficient to allow the reactions (1) and (9) to proceed completely, after the gasification in the raw gas there will always be some carbon black, which amount carbon black when using heavy fuel oil can amount to as much as 3% by weight of the starting material.

The further work-up of the raw gas formed during the gasification to the desired synthesis gas is nowadays mainly carried out in two essentially different ways: both are described by Samuel Strelzoff in an article in Hydrocarbon Processing, December 1974, p. 79.87.

In one of these reaction modes, the raw gas is cooled in a waste gas boiler and then further cooled to below the descent point in a soot removal system. The sulfur is then removed and the hydrogen sulfide is reprocessed, for example in a Claus factory. The next step is the conversion of carbon monoxide into carbon dioxide according to the so-called shifting process: CO + h2o f == - co2 + h2 (10).

which, if this reaction path is used, always takes place according to the high temperature shift reaction (at least 330 ° C) using high temperature shift catalysts, optionally followed by a low temperature shift reaction (up to about 200 ° C ). using a low temperature shifting catalyst. The high temperature shift catalysts consist essentially of oxides of Fe and / or Cr. If this type of shifting catalyst is used, the CO content can be reduced to about 3.5 mol%. If the two stage reaction is conducted using a low temperature shifting catalyst in the second stage, the CO content may be reduced to about 0.3 mol% based on the dry gas. The low-temperature shifting catalysts used in such embodiments of the process always contain Cu and ZnO and ey e a 2 ° 3 *. These catalysts are particularly sensitive to sulfur poisoning and very extensive removal. of all sulfur compounds from the gas is therefore necessary before it can be counted to the low temperature shift reactor. Since CO is a catalyst poison for ammonia catalysts, the residual CO remaining after the shift reaction must be removed, which usually takes place in this reaction way in a cryogenic manner by washing with liquid nitrogen.

If a low temperature shifting catalyst is used, it is also possible to remove the CO by methanation, ie by conversion to methane according to the reaction equation CO + 3HL · CH- + H90 (III 10

The methanation is. economically justified only if the carbon monoxide content is low and therefore cannot be used if the shift reaction is carried out only in the presence of a high temperature shift catalyst. Before washing with nitrogen or methanating, the carbon dioxide must be removed from the gas, which can be carried out by a further washing treatment. Washing with liquid nitrogen removes carbon monoxide, residual amounts of methane, argon and other gaseous impurities while at the same time adding a portion of the required nitrogen to the synthesis gas. In practice, the nitrogen is provided by first fractionating atmospheric air into an oxygen fraction and a nitrogen fraction, after which the former fraction is used for the partial oxidation and the latter fraction for washing with nitrogen.

In the other reaction route, the raw gas formed during the gasification is cooled directly by so-called quenching and at the same time the removal of soot takes place. In the present description, quenching is always understood to mean a cooling of the gas by direct contact with liquid water; it usually has a temperature of 150-250 ° C and is under the associated pressure. After removal of the carbon black, the water content in the raw gas is sufficient to justify the CO conversion at this stage by justifying the shift reaction. Since the gas still contains sulfur, it is necessary to use a sulfur-resistant shift catalyst, and since the sulfur-resistant shift catalysts known at the time of the development of this method are all high temperature -shifting catalysts, the CO conversion in this case is usually carried out at high temperature. Usually this takes place in two steps, after which the removal of sulfur compounds, in particular H2S, and of CO2 usually takes place in a single wash. The hydrogen sulfide is reprocessed, for example in a Claus factory. The purified gas contains about 4.8 mol% CO and is finally washed with liquid nitrogen, whereby the ammonia synthesis gas obtains the necessary amount of nitrogen.

In both cases a synthesis gas is obtained, which is compressed in a known manner and converted into ammonia.

In general, the two processes involve the same energy requirements and roughly the same capital investment for the installation of the necessary factories.

In the preparation of hydrogen, the final gas purification does not take place by washing with liquid N2 but, in contrast, usually by washing with a copper liquid, and the removed CO is recycled to the feed of the shifting department.

25 Swedish Patent Publication No. 394,192 (Patent

No. 7215398-4} invoking the priority right of British Patent Application No. 54987/71 of November 26, 1971, describes and claims rights for a process for converting and purifying a raw gas obtained by partial combustion of a fuel and mainly containing hydrogen, carbon monoxide and soot particles, to obtain a hydrogen-rich gas stream. The raw gas is cooled to 220-300 ° C. The cooling may start with a quench, but is terminated in a waste gas boiler, into which it must enter at a temperature of at least 900 ° C. After cooling, the carbon black present in the gas can optionally be partially removed by washing with hot oil or by passing cyclones. The CO

8101 433

»V

the f -6- is converted to soot-containing gas by passing it through (not through) catalyst beds in one or more reactors, which are of a complex construction with a number of wire mesh disks, which are separated and supported by spacers; this construction ensures that the carbon black remains in the gas rather than being deposited on the catalyst. If a number of shift reactors are used for the conversion, the gas is cooled between the real ones to 220-300 ° C, preferably by quenching. When the CO conversion is complete, the gas is cooled in a cooling zone, in which soot and ash are removed. The soot free gas is washed to remove condensate and freed from acidic components (S and CC 2) by purification, after which the residual amount of carbon oxides is methanated. Swedish Patent Publication 394,192 reports that the process is economical is because the conversion by the shifting reaction does not require cooling and reheating and, moreover, states that the process is advantageous because the carbon black does not have to be removed for conversion by the shifting reaction and, moreover, because the sulfur compounds after this conversion can be removed.

In some respects it may be advantageous to leave the carbon black in the gas during the reaction according to the "shift reaction", but in other "aspects this is very disadvantageous because it necessitates the use of the said complicated construction of the reaction" -tor (sl to avoid clogging or damage to the catalytic converter with soot. The fact that the gas - for the same reason - must be passed along the catalyst bed instead of through the catalyst bed is also a part, because this gives rise to an "insufficient contact between gas and catalyst and consequently" a low degree of conversion relative to the volume of the catalyst, necessitating additional capital investment for larger amounts of catalyst and larger reactors than would otherwise be necessary.

The object of the invention is now to provide a conversion of cheap fuels into hydrogen or ammonia synthesis gas, avoiding the above-mentioned drawbacks and which can be carried out at any desired temperature between the drop point and the highest possible temperature, which are determined on the basis of thermodynamic equilibrium considerations, and where both energy consumption and investment costs for the plant can be reduced. This is achieved by a new combination of measures known per se, in which combination, as in the above-mentioned Swedish patent publication, the conversion is carried out by the shift reaction before purification to remove the acidic components (i ^ S and CC ^) and is used for the CO removal.

The above object is achieved according to the method of the invention, which is characterized by the following combination of successive steps: (a) gasification of the starting material at an elevated temperature with an oxygen-containing gas and steam to form a raw gas , (B) cooling the raw gas from step (a) by quenching and / or steam production, (c) washing the cooled raw gas to completely remove soot and other possible solid impurities, (d) reheating the cooled of soot-free raw gas at a desired temperature by heat exchange with the product gas of a subsequent carbon monoxide conversion step (conversion of the washed soot-free reheated raw gas according to a shift reaction around the CO to CO2 and can be converted by passing through once or several times through one or more catalyst beds of one or more sulfur-resistant shifting catalysts, the r reaction heat can be used for the heat exchange with the gas at stage (dl, (f! removal of hydrogen sulfide and carbon dioxide from the gas obtained in the reaction reaction reaction, and subjecting the gas, which in this way has been substantially freed from acidic gaseous components, to a catalytic methylation process to remove the residual convert amounts of carbon oxides into methane.

This method differs in several respects from the method known from the above-mentioned Swedish patent publication. First, simple conventional reactors can be used in the process of the invention and no complicated reactors, as known in the art, are required. Since the carbon black is removed from the gas before the shift reaction, the gas can be passed through the catalyst bed without the risk of deposition of carbon black on the catalyst particles, thereby utilizing the catalyst in a much more effective manner. In contrast to the prior art, the gas is cooled and reheated before the conversion according to the shift reaction, however, a heat exchange is used to utilize the heat of the exothermic shift reaction to preheat the gas, which cooling reheating does not entail any visible disadvantage. It is not necessary to limit the quench application at step (b) to quenching the gas to a temperature above 900 ° C, thereby quenching and cooling by steam production.

25 can be adjusted in any desired manner, whereby this setting can be used to add exactly a desired amount of water (steam) to the gas. According to the prior art mentioned, it is prescribed that the temperature of the gas upon leaving. each shift reactor should preferably be 360-460 ° C, while in the process of the invention a gas temperature of 190-280 ° C can be set upon exiting the Placed shift reactor. This lower discharge temperature ensures a higher degree of conversion of CO.

The next part of the description is a detailed description and preferred embodiments. The pressure applied during the gasification can be any desired pressure between atmospheric pressure 8101433-9 and 200 bar. The gasification of coal will in many cases take place under atmospheric pressure, while in the gasification of heavy petroleum fractions, usually higher pressures will be applied. If the process aims at preparing ammonia synthesis gas, it will often be effective for the raw gas leaving the gasification stage to be under a pressure within the relatively high pressure range, which is virtually unchanged throughout the conversion of the raw gas into syngas. is maintained, whereby the increase in the pressure of the latter syngas in connection with the final conversion to ammonia, which normally takes place under a pressure of, for example, 150-250 bar, can be carried out in one single compression step. For example, it may be advantageous to obtain the raw gas under a pressure within the range of 30-125 bar, preferably 50-80 bar.

The cooling at step (b) can take place either only by steam generation or only by quenching, whereby partial removal of soot is already achieved at this step. According to the invention, however, the cooling is expediently carried out by a combination of quenching and cooling by producing high pressure steam. Using the combined method of cooling, it is achieved that the water vapor content can be predetermined to a desired value by selecting the appropriate proportion of the amounts of heat, which are partly removed by quenching and partly by steam production. This is especially useful for the next conversion according to the shift reaction, because in this treatment step optimum utilization of the steam content, which is smaller than usual, is achieved by quenching alone.

In many cases it is advantageous to quench the raw gas to. a temperature within the range of 400-800 ° C and the further cooling to be carried out by steam production.

Although some of the solids are removed by quenching, soot is removed by washing with water. The soot removal can be carried out by any conventional method.

Before the CO conversion according to the shift reaction, the soot-free gas is heated to the desired temperature by heat exchange between the inlet and outlet of the CO conversion system. On its own, the reaction can take place at any temperature between the descent point and the maximum temperatures determined by the equilibrium temperature. As noted above, it is desirable for thermodynamic considerations to use the lowest possible conversion temperatures, the temperatures being otherwise limited by the descent point, for example, with an elevation of about 30 ° C, although the temperature limits for the 15 activity of the catalyst must be taken into account.

The conversion according to the shift reaction can take place in one or more shift reactors and with one or more sulfur-resistant shift catalysts. In principle, at least the last part of the shifting process is a low-temperature shifting reaction and is used both as a high temperature shifting catalyst and also as a low-temperature shifting catalyst at temperatures up to about 190 ° C. of a special catalyst capable of operating in a sulfur-containing atmosphere. The availability of such a catalyst is an important requirement for the invention.

A particularly suitable catalyst is described in German Patent Publication No. 1,928,389. According to the invention, therefore, a catalyst with or without catalyst support is suitably used, which consists of (a) at least one alkali metal compound prepared from -3 an acid with dissociation constant of less than 1 x 10, 35 and ( b) a hydrogenation dehydrogenation component of at least one element belonging to group VB (vanadium, niobium, tantalum), VIB (chromium, molybdenum, tungsten) and VIII (iron, cobalt, nickel, the precious metals) of the periodic table '61 01 4 33 -11- or a compound thereof, wherein the ratio a: b is 1: 0.001 to 1:10. The catalyst can be sulfided. Component (a) may advantageously be a kaliura salt or cesium sulfide. As the component (b), a combination of metals or metal compounds, particularly nickel and tungsten, such as molybdenum, cobalt and molybdenum or iron and chromium, is particularly preferably used. As noted, the conversion according to the shift reaction takes place under such conditions, in particular with regard to pressure, temperature and steam content and possibly nitrogen content in the gas, that a final temperature is reached which is only slightly above the drop point of the gas. More particularly, the conditions of the invention can be controlled to achieve the lowest possible final temperature 15, which is sufficiently above the gas drop point to protect the catalyst from condensation of water vapor. The conversion according to the shift reaction takes place particularly advantageously under conditions such that a final temperature of 30-60 ° C above the gas drop point, preferably about 40 ° C above the drop point, is reached. In practice, it is usually possible to carry out the reaction reaction reaction or at least the last part thereof at temperatures within the range of 190-280 ° C.

It is advantageous that the conversion according to the shift reaction can be carried out at least partly and at least as far as the last part thereof is concerned, because this involves a higher degree of conversion of carbon monoxide into carbon dioxide than at higher temperatures, because the reaction (10) is favored thermodynamically to the right by lower temperatures and to the left by higher temperatures. Instead of a content of about 3.5% CO, it is possible in the process according to the invention, if an active low-temperature shifting catalyst is used, even in the presence of gaseous sulfur compounds a content of about 0.5% CO or achieve less. A higher yield of hydrogen is hereby obtained. Furthermore, this has the advantage that the residual amount of CO can be removed by methanation according to the reaction (11). The methanation of such small amounts of CO is economically possible, while moreover. the advantage is achieved that investment costs, operating costs and energy consumption for the cryogenic unit for cooling to temperatures between -175 and -200 ° C, which are necessary when carbon oxides are removed by nitrogen washing, are avoided. As has already been pointed out, it is not possible to economically remove as large amounts of CO as 3.5% by methanation.

As will be apparent from the above comments regarding the known processes for preparing ammonia synthesis gas from petroleum fractions, it is most advantageous to carry out the shift reaction conversion prior to sulfur removal because the sulfur ( especially in the form of hydrogen sulfide) then can simultaneously remove with carbon dioxide in one wash to remove acid gases. Until now, it has not been possible to use low temperature shift catalysts in the presence of sulfur because they are all sensitive were for sulfur and were very quickly poisoned with sulfur. The above-mentioned sulfur-resistant catalysts are not only resistant to sulfur, but even require the presence of a certain minimum amount of H 2 O.

An advantage of the conversion process used is that even at low water to dry gas ratios no significant methanation is caused according to the reaction equations (11) and (12). A significant methanation would give rise to a loss in the hydrogen synthesis. It is true that the methane formed could be utilized as a fuel in the process, but excessive amounts of methane will adversely affect the economic aspect of energy consumption, firstly because it is complimented to a high pressure but must be used under low pressure and secondly because the removal as such (for example 81 01 433 -13- in a cryogenic purge gas extraction unit) requires the supply of energy.

The conversion of the carbon monoxide from the raw gas, which, as noted, forms hydrogen, usually takes place by means of a catalyst, which is useful in the shifting reaction at both low and high temperature, for example at 190-480 ° C. and which permits or even requires the presence of sulfur. The flow rate of the gas is not a critical factor and it is possible to use space velocities commonly used in these reactions, for example, space velocities within the range of 300-30,000 vol. Units of gas per vol. part catalyst per hour (Nm / m '..h). Even if the shift reaction can take place at a high temperature, it is of the greatest advantage for the above reasons to terminate the shift reaction at the lowest possible temperature still above the drop point, because condensation of liquid water on the catalyst can cause damage. of the catalyst.

Thanks to the sulfur tolerance of the catalyst, the acid gases, ie mainly carbon dioxide and hydrogen sulfide, can be removed after the shift reaction, which is of the greatest advantage for the reasons mentioned above in terms of the economic aspect of the energy consumption. The removal can take place in a known manner and a number of suitable methods are described in the article "Merits of acid-gas removal processes" by K.G. Christensen and W.J. Stupin, Hydrocarbon Processing, February 1978, pp. 125-130. As examples, here the absorption in a polyethylene glycol dimethyl ether-containing solvent (the "Selexol" process), the absorption in a promoter-containing hot potassium carbonate solution (the Ben-field process), the absorption in potassium salt solutions (the "Catacarb" process), the absorption in methanol (the "Rectisol" -35 process), the absorption in diglycolamine and the absorption i ... with various other amines are mentioned.

The low temperature at the end of the shift reaction allows, as noted, a high degree of conversion of CO 1014 14 33-14, so that the residual content of the carbon oxides, CO and CC 2, after the removal of the acid gases is low is enough to remove it advantageously by methanation. This avoids washing with nitrogen, which is expensive because of the high energy consumption for cooling.

The process and the catalyst used also have the advantage of achieving a more complete conversion of carbonyl sulfide to CO2, which can be easily removed by removing the acidic gases, whereby the washed gas will not contain sulfur compounds which disrupt later processes, such as the ammonia synthesis.

The purification of the gas from acid gases obtained in the shift reaction, that is to say in particular H 2 S and CC 2, can be carried out by a number of known methods. After the removal of the acidic gases, a small amount of CO remains, and a small amount of CO2 may possibly also remain in the gas. Both are almost completely removed by said methanation treatment, which, as far as the CO is concerned, takes place according to the reaction (11) while the methanation of the CO2 proceeds according to the reaction scheme CCL + 4H0 -> CH, + 2H-0 (12).

25 *

If the process is used to prepare hydrogen, it is completed. If the process is used to prepare aramonia synthesis gas, nitrogen must be added. This can take place by direct addition of N2, but according to the invention can take place in a very favorable manner by using oxygen-enriched air as the oxygen source for the gasification of the starting material, whereby the nitrogen will be present in the gas during the entire series. reactions 35 of (b) - (g).

This has the advantage that a dilution of the raw gas is achieved, whereby the equilibrium content of methane in the raw gas under conditions of equal total pressure and temperature will be lower than under conditions, whereby the gasification with pure oxygen is carried out. The presence of nitrogen in the raw gas also provides an increase in the heat capacity of the gas and a decrease in the descent point, which in turn implies that the shift reaction can be carried out at a lower temperature thereby providing a favorable thermodynamic conversion equilibrium that is to say a higher degree of conversion to H 2 than would otherwise be the case. Finally, by using oxygen-enriched air in gasification, savings are made on the purchase of pure oxygen or on setting up a factory for oxygen production.

In the conventional nitrogen wash as used, for example, in the above-described known processes, an N2 content in the purified gas of about 10% is reached, after which N2 is further added to the stoichiometric ratio of H2 to N2 for the ammonia synthesis reach. Therefore, gasification with oxygen enriched air is not advantageous in combination with nitrogen washing because an N2 content above about 10% would simply condense in the wash column, leading to a significant increase in the energy required for cooling.

The method according to the invention is particularly useful if heavy petroleum fractions are used as starting material. The crude gas is formed by the gasification of the hydrocarbon cool material either with pure oxygen, if hydrogen is to be prepared, or for the preparation of ammonia synthesis gas, preferably with oxygen-enriched air, in both cases steam is added for the exotherm reactions (3) and (8). This usually raises the temperature to 1300-1400 ° C. The crude gas formed by the gasification is cooled, preferably for the reasons set forth above, by a combination of quenching and further boiler cooling. Thus, during cooling, the heat content of the raw gas can be partly utilized in a waste gas boiler for the production of high-pressure steam. After cooling, the gas is further cooled in a carbon black washer to remove carbon black and possibly other solids in a known manner. The cooling takes place to a temperature close to the drop point of the raw gas. The temperature reached and the steam concentration achieved in the gas depend on the total pressure and the relative ratio of the amounts of heat that are removed by quenching, respectively. steam production. Advantageously, these parameters are mutually adjusted so that the steam concentration reaches exactly that concentration, which is optimal for the later shift reaction.

If, according to the method of the invention, hydrogen is to be prepared, pure oxygen is also used for the gasification. If ammonia synthesis gas is to be prepared, it is advantageous to use oxygen-enriched air instead, which is obtained by mixing air from the atmosphere with oxygen. »> The ratio can be calculated in such a way that the synthesis gas is the methanation process and an optional mixing of a hydrogen-rich fraction, which comes either from the process according to the invention of a raw gas, which is formed by gasification with steam and pure oxygen, or from an extraction unit for purge gas, containing substantially the stoichiometric amount of nitrogen to form ammonia, i.e., a H 2: N 2 ratio of about 3: 1. However, other hydrogen to nitrogen ratios are also eligible.

The method according to the invention will now. are illustrated by a calculated example for the preparation of ammonia synthesis gas from heavy oil, which is gasified with enriched air.

Example 35 It is assumed that the following flows must be gassed:

Fuel oil: 32.2 t / h (C 85.3%> H 10.5%, S 4.0%, N 0.2%)

Enriched air: 55.281 Nm3 / h (02 43.9%, N2 55%, Ar 1.1% 8101433 -17- Λ Λ overpressure 85 kg / cm, 600 C, prepared by mixing 98.5% 02 with air.

Steam: 13.0 t / h.

This produces a raw gas of the following composition (water vapor is disregarded):

Mol% H2 34.0 N2 24.2 CO 37.0 10 CO2 3.4

Ar 0.5 CH4 0.25 H2S 0.7 COS 0.01 2 15 Temperature 1365 ° C, overpressure 80 kg / cm, flow 3 3 speed 125,920 Nm / h calculated as drying gas and 135,350 Nm / h calculated as wet gas .

The discharged gas is quenched to 650 ° C and further cooled to 340 ° C in a boiler. About 42 t / h of saturated steam of 115 bar are thereby formed.

After the boiler, the gas is further quenched in a washer to a drop point of 240 ° C, thereby achieving a water to dry gas ratio of 0.78. The total amount of quenching water is 71,830 kg / h.

25 CO conversion

The purified gas exiting the soot scrubber is heated by heat exchange between inlet and outlet to 280 ° C and passed through three interconnected CO converters which converters are all reactors with a downward flow and a fixed catalyst bed.

The composition of the dry gas (mol%) after the converters as well as further data are shown in the following table: 8101433 -18-

Converter 1 - Converter - 2.- Converter 3 [H2 49'2 51.2 51.4 N2 18r6 * 7.8 17.8 C0 5? 2 Ir1 0.7 C02 25.9 28.8 29.0

Ar 0.4 0.4 0; 4 CH4 ° 2 0.2 0.2 H2S ° r5 0.5 0r5 COS 100 ppm 21 ppm 13 ppm

Drained flow of dry gas,

Nm3 / h 164,000 170,710 171,410

Supply / exhaust temperature (OC) 280/441 250/280 245/248

HoO / dry gas, supply 0.78 0.37 0.32.

The heat of the reaction is used to generate high-pressure steam by preheating the boiler feed water as much as possible. Optionally, an absorption cooling device can be used to recover heat up to 120 ° C.

Acid gas removal.

The gas obtained in the process is sent to a factory to remove acidic gases, for example a Selsxol plant, in which CO2 and H2S are removed and separated, thereby obtaining an H20-rich stream, which is used in a Claus factory .

The thus purified gas is then methanized to remove the residual CO and CO2.

The composition (mol%) after removal of the acid gases and the methanation as well as other data are shown in the following table.

8101433 -19-

After removal Na of acid gases iaethaniserinq H2._ 73.0 72.04 N2 ~ 25.2 26.06 CO 1.0 CO2 0.1

Ar 0.5 0.52 CH, 0.25 1.38 4 o

Dry gas discharge, Nm / h 120,440 116,400

Temperature inlet / outlet (° C) 320/389 2

Overpressure 70 kg / cm

Ammonia synthesis

The methanized gas is mixed with a Herijk gas, which comes from a purge gas recovery device, after which the resulting synthesis gas is fed to the synthesis after compression.

The synthesis reactor, which is operated under an overpressure of 2 160 kg / cm, is a reactor, as described in Danish patent application no. 1041/77, with a steam boiler and a boiler water preheater for cooling the gas, which reactor.

The purge gas is passed to a cryogenic purge gas recovery device, in which most of the Ar and CH 2 are removed by condensation and the hydrogen-rich fraction is recycled to the suction side of the compressor 15.

The gas composition (mol%) and amounts of the Streams are as follows:

Hydrogen-rich Supplemental gas Reactor gas from the remainder for the supply discharge gas extraction synthesis unit____ H2 89.96 73.57 64.62 52.97 N2 8.39 24.55 21.55 17.67 NH3 3.82 17 99

Ar 0.98 0.56 3.00 3.40 CH4 0.67 1.32 7.01 7.97

Dry gas flow Nicr / h 10,890 127,290 457,270 402,350 8101433

Claims (9)

1. Process for the conversion of coal and / or heavy petroleum fractions as starting material to hydrogen or an ammonia synthesis gas consisting essentially only of hydrogen and nitrogen, characterized by the following combination of successive steps: (a) gasification of the starting material at an elevated temperature with an oxygen-containing gas and steam to form a raw gas, (b) cooling the raw gas from step (a) by quenching and / or steam production, (c) washing the cooled raw gas to remove soot and other possibly present to completely remove solid impurities, (d) reheating the cooled soot-free crude gas to a desired temperature by heat exchange with next stage product gas for carbon monoxide conversion, (e) crop conversion , of soot-free, reheated crude gas according to a shift reaction to convert the CO into CO2 and H2 by passing through one or more times through one or multiple catalyst beds of one or more sulfur-resistant shift catalysts, the heat of reaction of which is utilized for heat exchange with the gas in step (d), (f) removal of hydrogen sulfide and carbon dioxide from the gas obtained in the shift reaction, and (g) Topics of the gas liberated in this way from acid gas constituents in a catalytic methanation to convert residual amounts of carbon oxides into methane. 2. Process according to claim 1, characterized in that the raw gas is cooled at step (b) by a combination of quenching and production of high-pressure steam. Method according to claim 1 or 2, characterized in that the gas is quenched to a temperature of 500-800 ° C in step (b), at 8101433 ft -21. 4. Method according to any one of claims 1-3, characterized in that two or more reactors for the CO shift reaction are used in step (e) and the gas between the reactors is cooled by heating boiler feed water and high develop pressure steam. 5. Process according to any one of claims 1-4, characterized in that the shift reaction is carried out under such conditions that the lowest possible final temperature is reached, which is sufficiently above the drop point of the gas to prevent the catalyst from condensation of steam to protect. 6. Process according to claim 5, characterized in that the shifting reaction is carried out under such conditions that a final temperature of 30-60 ° C above the descent point of the gas, preferably about 40 ° C above the descent point, is reached. 7. Process according to claim 1, characterized in that the shift reaction is terminated at a temperature within the range of 190-280 ° C. 8. Process according to one or more of the preceding claims, characterized in that as the sulfur-resistant catalyst for the shift reaction a catalyst with or without support is used, which consists of (a) at least one alkali metal compound prepared from a -3 acid with a dissociation constant of less than 1 x 10, and (b) a hydrogenation dehydrogenation component of at least one element of group VB, VIB and VIII of periodic system or compound thereof, wherein the ratio of a: b 1: 0.001 to 1:10. Process according to any one of the preceding claims, characterized in that oxygen-enriched air is used as the oxygen source for gasification in step (a). 8101433