DE2705673A1 - Catalytic syntheses with high yields - suitable for mfg. ammonia, methane, methanol, or the conversion of carbon monoxide - Google Patents

Abstract

A reversible, exothermic, gas-phase reaction is undertaken where a gas stream contg. one or more reactants is fed through >=1 catalyst zones to obtain >=1 prods. The gas stream is fed at temp. (T1) into a first reaction zone (R1) using adiabatic conditions so as higher temp. (T2) is attained; T2 is lower than the inactivation temp. of the catalyst. The gas at T2 then flows into a second zone (R2) provided with continuous external cooling to obtain a prod. mixt. leaving zone (R2) at temp. (T3) which is lower than T2. The gas may be recycled through the process and T3 is pref. max. T1. The initial gas is pref. a mixt. of (a) N2 and H2 for mfg. NH3; or (b) H2 and CO for mfg. methanol; or (c) COx and H2 for mfg. methane; or (d) H2 and CO, and using a CO conversion catalyst. Improved yields in the synthesis of cpds. such as CH3 OH or NH3 are obtd. For example, the % of NH3 in the outlet gas can be raised to 20% c.f. 16.5-17.5% obtd. in conventional processes.

Description

gatalytisches procedure

The invention relates to a catalytic process, in particular for carrying out reversible exothermic gas phase reactions that are caused by solid Catalysts are catalyzed.

Typical examples of such reversible exothermic gas phase reactions, which are used on an industrial scale are methanation, methanol synthesis, Ammonia synthesis and CO conversion, to name just a few.

It was recognized long ago that the product yield was reversible exothermic gas phase reaction is small, albeit high temperatures for high reaction speeds are conducive and the response can progress to near equilibrium. If on the other hand the temperature is decreased, the reaction rates are slower although the reaction is to a more favorable product yield and reagent conversion and likewise close to equilibrium. The result is that a correspondingly larger Catalyst volume can be used ms R.

It is also generally accepted that for a given reaction system and a given input gas composition can achieve a maximum conversion, when the temperature along the path of the reactant gases is so controlled that the reaction rate at j Every point of the reaction path in the in concentration values prevailing at that point is as high as possible.

There are many suggestions, the gas composition and the temperature profile of the reactants as they pass through a catalyst bed or beds to keep under control for the purpose of optimal reaction conditions. The achievement However, optimal reaction conditions are at best in all known proposals an approximation.

In the field of ammonia production, an example was used Overview of available procedures given by J. B. Allen (Chemical and Process Engineering, September 1965, Pages 473 to 483). Figure 6 on page 477 of this article shows typical temperature profiles for various reactor designs. These also include adiabatic reaction stages with multiple beds with either indirect cooling between the stages ("indirect quench cooling") or with freezing of cold gas between the stages ("direct quench cooling" or "cold shot1). How As can be seen from the drawing, both solutions show considerable temperature deviations from the ideal response rate curve. As admitted in the article, such cooling converters are not as efficient in terms of catalytic converter utilization like other clay constructions, such as the so-called "pipe-cooled" construction.

The percentage conversion of nitrogen to ammonia in each adiabatic Level is usually quite low (e.g. in the range of about 5 to about 20 % Sales per pass), and high sales require numerous passes through the Catalyst in each case with a subsequent cooling stage. This leads to high investment and operating costs.

With a "tube-cooled" converter, the reactant gases are before passing over the catalyst by passing it through catalyst bed cooling tubes preheated.

With this arrangement, a countercurrent or direct current advance warning of the reactants and a bed cooling achieved. But since the construction is an internal Cooling by the reactant gases themselves is the rate of heat removal by the heat capacity of the incoming gas is limited. As the temperature profile closer to the ideal reaction rate curve, these are tube-cooled Converters compared to converters with quench cooling in terms of catalyst utilization more powerful.

A further overview of ammonia synthesis reactors is contained in Article on ammonia in Ulliazin Encyclopedia of Technical Chemistry, 4th ed. (1973), M. 7, pages 445 to 513, published by Verlag Chemie GmbH.

It has also been suggested to use a tube-cooled reactor that is particularly suitable for the synthesis of methanol, as the first reaction stage Adiabatic stage to be provided.

This proposal is shown, for example, in FIG. 5 on page 387 in M. 13 by Kirk-Othmer, Encyclopaedia of Chemical Technology, 2nd ed., Published at John Wiley & Sons, Inc. Like a simple tube-cooled reactor the amount of heat recovered from the second stage catalyst bed, i.

the tube-cooled bed, can be removed by the heat capacity of the inlet gas limited.

A specific limitation of a pipe-cooled reactor and each another type of reactor using the inlet gas as internal coolant - as already mentioned -the Heat capacity of the input gas. at highly exothermic reactions can cause this limitation to a certain extent Reduction of the inlet gas composition can be remedied, whereby the effective Reduced concentration of one or more reactants and / or the volume of the inert components increased. For example, the reactants with cold Product gas can be diluted. However, this requires a large feedback loop the associated high system and operating costs due to large recirculation fans and / or compresors.

Another type of converter for performing reversible exotherms Gas phase reactions is the so-called pseudo-isothermal converter. With this type of converter, which has found industrial entry in the field of methanol synthesis, is the catalyst bed is cooled externally by a circulating coolant, it can Evaporative cooling or cooling can be used without evaporation; Using of water as a coolant, the high pressure or low pressure steam generated can be anywhere used in the system or at the system boundary for use in other processes be delivered. Because the heat of reaction is continuously dissipated by the coolant is, the initial temperature rise along the reaction path is lower than for an adiabatic bed, and therefore the speed of approach to the Maximum response rate curve slower than that of an adiabatic Bed. As a result, the catalyst utilization is relatively little in this system effectively.

With a pseudo-isothermal converter cooled by evaporation is the coolant temperature over the entire length of the reaction path essentially constant. It is advisable that the coolant temperature be above the light off temperature of the catalytic converter, i.e. the effective minimum temperature of the catalytic converter operation, is to deter the reaction at the entrance of the bed due to the cooling effect to counteract the coolant if in the course of the catalyst aging the Quenching exceeds the rate of heat build-up at the entrance end. As the reactants pass through the bed, the temperature of the gas mixture increases up to a maximum (the "hot spot"); then it decreases as the reaction rate increases slowed down, and exceeds the cooling effect brought about by the coolant the rate of exothermic heat generation. With the aging of the catalytic converter this hot spot moves along the bed away from the entrance end. This can complicate the converter construction because of the movement of the hot spot and the aging of the catalyst must be allowed at the entrance end of the bed.

To some extent, these problems can be overcome by countercurrent cooling can be dissolved without evaporation. In this way, the outlet temperature of the gühlmitter s always like that be chosen so that they match the light-off temperature of the catalyst and possible quenching difficulties are avoided. Nevertheless, they remain with the aging of the catalyst with the shifting of the droppings spot there are problems associated along the catalyst bed.

One embodiment of a wind direct "quench cooling converter" is shown in U.S. Patent 2,898,183.

An example of a cold shot type ammonia converter is shown in Figure 24 on page 287 of Vol. 2 in tirk-Othmer, Encyclopaedia of Chemical Technology, 2nd edition. Other embodiments of converters of the Cold Shot fZps are bat play-wise described in U.S. Patent 3,254,967 and British Patent 1,213,045.

Converters with different internal cooling for example described in GB-PS 1,272,001, 1,356,151 and 1,387,044 and in U.S. Patent 3,440,021.

Pseudo-isothermal reactors with evaporative cooling are described in GB-PBs 1,219,973 and 1,223,761 and in US-PS 2,662,911. A multi-stage The individually cooled stage reactor is described and illustrated in U.S. Patent 2 590 436 The present invention is therefore based on the object of known reactors and processes discussed above to improve.

According to the invention, a reversible, exothermic gas phase reaction is proposed to be carried out catalytically under adiabatic conditions in a first reaction zone to a hot, near-equilibrium gas mixture, which is followed by an externally cooled second The reaction zone arranged on the downstream side is connected, so that the reaction temperature is continuously reduced. In this way, the heat of reaction and the palpable The heat of the gas mixture increases as the gas flows through the second reaction zone Dimensions removed, so that there is an overall improvement in the reaction kinetics.

According to the invention, a method for carrying out a reversible Exothermic gas phase reaction provided in which one or more gaseous reactants exothermic and reversible with the formation of one or more gaseous products react, characterized in that there is a gaseous reactant feed stream containing a first temperature of a first reaction zone supplies the one for the gate analysis of the exothermic reaction at the first temperature contains effective catalyst, the feed stream under essentially adiabatic conditions Allows conditions in the first reaction zone to react, from the first reaction zone withdraws a gas mixture at a second temperature which is higher than the first temperature, the gas mixture at substantially the second temperature a second reaction zone is fed, one for catalyzing the exothermic reaction contains effective catalyst at the second temperature, the heat of reaction from the gas stream as it passes through the second reaction zone by external heat exchange discharges continuously with a coolant and from the second reaction zone at a third temperature, which is lower than the second temperature, contains a product Gas mixture withdraws, the first temperature and the composition of the feed stream are chosen so that the second temperature is below the inactivation temperature of the catalyst or catalysts of the first and second reaction zones held will.

The invention also provides an apparatus for performing a reversible exothermic gas phase reaction in which one or more gaseous reactants exothermic and reversible with each other with the formation of one or more gaseous Products react, characterized by a first, a first reaction zone determining reactor, the first one, effective for catalyzing the reaction catalyst contains, feed means for the supply of a gaseous reactant containing Feed stream at a temperature above the catalyst light-off temperature of the first catalyst bed, defining a second, second reaction zone Reactor containing a second catalyst bed effective for catalyzing the reaction contains, wherein the second reaction zone is connected to the first reaction zone, heat exchangers assigned to the second reaction zone, which are used to remove the in the heat developed in the second reaction zone serve and with this zone in heat exchange stand, means for supplying a coolant to the heat exchangers and Means for brewing a stream containing the gas product from the second reaction zone, wherein, during operation, the gaseous reactant or the gaseous reactants the first reaction zone at a temperature above the light-off temperature of the are fed to the first catalyst bed in a reaction in the first reaction zone under essentially adiabatic conditions and an exit from the zone at a second temperature above the first temperature, but below that Inactivation temperature of the catalyst or the catalysts of the first and second reaction zone, and wherein the gas mixture from the first Reaction zone essentially at the second temperature of the second reaction zone for further implementation and the wire exchanger for ongoing Removal of the heat of reaction from the gas mixture as it passes through the second Serve reaction zone so that the mixture with a third temperature from this Exits zone which is below the second temperature, and from the second reaction zone a mixture containing the gaseous product is obtained.

The inlet gas composition and inlet temperature are common the first adiabatic reaction zone is chosen, and the first reaction zone is designed in such a way that the reaction creates a hot, equal weight at its outlet end Mixture has formed. This near-equilibrium mixture then serves as feed for the second reaction zone, the heat dissipation through the external coolant a change in the near-equilibrium mixture caused by the fact that a constant temperature decrease along the catalyst bed brought about and so more Implementation to the desired product is made possible. An uncooled first reaction zone under essentially adiabatic conditions (neglecting heat losses, which are unavoidable in practice) enables the reaction to occur with the greatest possible Speed on temperature / composition terms and conditions the maximum catalyst activity increases, so that the maximum utilization of the catalyst results.

When the conditions in the first reaction zone are such that the Reaction to a state of equilibrium, the outlet temperature from the first reaction zone, i.e. the second temperature, are precisely determined in advance, when the appropriate thermodynamic data are available.

In this way, the second reaction zone is with a gas stream charged of known predetermined temperature and composition, and - since the The hot spot lies in the first and not in the second reaction zone - the construction the container for the second reaction zone is facilitated.

The cooling can in the second reaction zone except for any desired outlet temperature (third temperature). As a precaution, the Coolant supply controlled so that the temperature / composition conditions in the second reaction zone at or near the line of the maximum reaction rate being held. In this way, the efficiency of the catalyst utilization will be increased maximized in the second reaction zone.

In certain cases it will be appreciated if the first reaction zone is designed so that the temperature does not peak in the first reaction zone reached, but instead its at the entrance end of the second reaction zone continues to rise slightly. In such cases the hot spot is in the second reaction zone, and the second temperature (i.e. the exit temperature of the first reaction zone) can be found on a temperature / composition diagram on the opposite page the curve of maximum reaction rate from the equilibrium curve. Of course, only then will one benefit from the first reaction zone in this way if it is possible to get closer to the curve of maximum speed as if the reaction in the first reaction zone was essentially adiabatically runs to equilibrium so that the hot spot is in the first reaction zone occurs and corresponds to the second temperature. With the aging of the catalytic converter it can also happen that the hot spot is at the inlet end of the cooled second Zone advances, although by design it should be in the first reaction zone.

However, since the adiabatic response is usually very fast up to is the difference between the second Temperature and the peak temperature of the hot spot - if it exists at all - usually very small, e.g. on the order of 10 to 20 ° C or the like, see above that the hot spot remains close to the entrance end of the second reaction zone and so the Design of the second reaction zone simplified.

In an expedient management, the first and the second Reaction zone adjoining parts of a plug flow reactor. In the first Part of the reactor near the inlet end, the reaction takes place essentially adiabatically, and the temperature rises as the gas passes along the bed.

In the first adiabatic reaction zone, the conversion of the starting material can in the product will be low as a result of the high temperature reached, which is the equilibrium concentration of the desired product. By connecting a cooling stage to this In the adiabatic stage, the heat of reaction is increasingly derived from the gas stream dissipated, the temperature is continuously reduced, the equilibrium is shifted, and a further conversion to the desired product can take place. Because the heat of reaction is now continuously discharged, the reaction also proceeds, provided that that the catalyst bed is sufficiently large for the reacting gases to cool down are that either the reaction comes to a standstill or has ended.

According to another embodiment, the first and the second Reaction zone separate reaction vessels.

The catalyst of the first reaction zone can with that of the second Reaction zone identical or different from it be in which Fall the second temperature also below the inactivation temperature of the catalyst must lie in the second zone. Any catalyst that works for the reaction in question suitable can be used in the process according to the invention.

The reaction can be any reversible gas phase exothermic reaction and any suitable solid catalyst can be used. Reactions Of particular interest, however, are the methanation (methane formation) of carbon monoxide and / or carbon dioxide, methanol synthesis from carbon monoxide, carbon monoxide conversion and the synthesis of ammonia.

Carbon monoxide and hydrogen react together according to the reversible reaction The forward reaction (methanation) can be used to form a replacement natural gas, while the reverse reaction is known as the steam reforming of methane and is an important basis for the production of synthesis gas. A similar reaction occurs between carbon dioxide and hydrogen according to the reaction equation These reactions (1) and (2) can be carried out under atmospheric pressure or elevated pressure. Low temperatures, for example in the range from about 180 to about 400 ° C., promote the highly exothermic methanation reaction, while high temperatures, usually in the range from about 750 to about 900 ° C., promote the endothermic reverse reaction. Suitable catalysts for reactions (1) and (2) are the catalysts containing a Group VIII metal, such as supported nickel oxide catalysts, for example a catalyst composed of nickel on aluminum oxide.

Other methanation catalysts are catalysts based on Ruthenium, platinum and palladium.

When carrying out the methanation reaction on a larger scale for generating a substitute natural gas according to the present invention the feed stream is a mixture of one or more carbon oxides, preferably Carbon monoxide alone, and hydrogen. The catalyst of the first and the second The reaction zone is a methanation catalyst, e.g. one of the methanation catalysts mentioned above, and the first and second temperatures are at least as high as the light off temperature of the methylation catalyst of the first and the second reaction zone. The composition of the inlet gas stream is preferably chosen so that a suitable amount of hydrogen is present in proportion to carbon oxide or carbon oxides, as in the above Equations (1) and / or (2) is required. Usually the pressure at this Process in the range of atmospheric pressure or less than atmospheric pressure up to about 100 atmospheres or more. The first temperature depends on the catalyst chosen and is usually in the range of about 200 OP up to about 600 ° C, while the second temperature is in the range of about 400 ° C. to about 1200 ° C. or above, preferably in the range of about 800 to about 900,000. The third temperature is preferably in the range from about 200 0C to about 350 OC, the exact temperature values depend on the species the catalyst used, the inlet gas composition, the design of the Reaction zones, the rate of heat dissipation by the coolant and other factors.

Methanol is produced on an industrial scale by reacting carbon monoxide with hydrogen after the reversible reaction manufactured.

This equilibrium reaction is directed towards the methanol synthesis Favorable by increased pressure, but adversely affected by an increase in temperature. The forward reaction, i.e. the methanol synthesis, is the same as in reactions (1) and (2) exothermic, while the reverse reaction, the decomposition of methanol, is endothermic. In the For methanol production, the temperature is usually maintained at about 200 to 300 ° C at a reaction pressure in the range of about 20 to about 360 atmospheres. Suitable Catalysts are mixed oxides of zinc, Chromium, manganese or aluminum, e.g. zinc oxide with chromium oxide as a promoter (with a content of e.g. 10 Wt .-% chromium oxide) and copper oxide supported catalysts. Other catalysts are for example, described by Richard M. Stephenson, Introduction to the Chemical Process Industries, (1966) pages 306-308, published by Reinhold Publishing Corporation.

According to the invention, the methanol synthesis takes place in a first and a second reaction zone with a methanol synthesis catalyst, e.g. methanol synthesis catalysts mentioned above, and the feed stream comprises one Mixture of hydrogen and carbon monoxide (preferably in a ratio of H2: CO of 2: 1), while the first and second temperatures are at least as high as the Light-off temperature of the ethanol synthesis catalyst of the first or the second Are reaction zone. Since the methanol synthesis is accompanied by a reduction in volume, the reaction is promoted by increased pressures, the pressures expediently for example, in the range of about 5 to about 360 atmospheres or more and, inter alia, on the catalyst activity and the reaction temperature ranges used in the process depend. Preferred methanol synthesis pressures are in the process according to the invention in the range of about 10 to about 150 atmospheres, for example in the range of about 20 to about 100 atmospheres.

The temperatures used can vary within wide limits.

For example, the first temperature can be in the range of approximately 150 to about 300,000, the second temperature in the range of about 200 to about 350 ° C. and the third temperature preferably in the range from about 150 to about 300 ° C.

Another reversible exothermic gas phase reaction of industrial importance is ammonia synthesis. This takes place after the reaction The forward reaction is favored by high pressures and low temperatures, while the reverse reaction is supported by high temperatures and low pressures. Typical operating conditions in a conventional anonia synthesis plant are 350 to 550 ° C and 50 to 350 atmospheres. The catalyst is usually an iron oxide catalyst, which can contain silicon dioxide and, for example, aluminum oxide and potassium oxide as promoters. Under these conditions, nitrogen to ammonia conversions of the order of 15 to 50% can be achieved in a single pass; normally the unreacted nitrogen and hydrogen are returned to the reaction after removal of the ammonia product.

An example of a commercial ammonia synthesis catalyst is an iron oxide such as magnetite (Fe304) with a content of 0.6 to 2.0% Al203 and 0.3 to 1.5% K20. Other catalysts for the synthesis of anonia are for example on pages 112 to 115 of the aforementioned book by Richard Pl. Stephenson described.

If the invention is used in the field of AzEImonisynthesis the feed stream of a mixture of nitrogen and hydrogen, preferably in a ratio of N2 to H2 of 1: 3. The catalyst of the first and second Reaction zone is an ammonia synthesis catalyst, while the first and second Temperature at least as high as the light-off temperature of the catalyst of the first or the second reaction zone. The pressure can be in the range of about 20 atmospheres or less up to about 400 atmospheres or more. Typical operating conditions range from about 30 atmospheres to about 250 atmospheres. The catalyst or the catalysts can, for example, be any of the above-mentioned monoxide synthesis catalysts be. The first temperature can be in the range from about 200 to about 600 ° C., preferably in the range from about 300 to about 500 OC and especially in the range of about 350 to about 480 OC.

The second temperature is preferably in the range of about 400 ° C to about 650 ° C, preferably in the range of about 480 ° C to about 550 ° C.

Another reversible exothermic gas phase reaction of industrial importance is the so-called CO shift reaction, in which carbon monoxide and water vapor according to the reaction equation react.

The forward reaction is exothermic, so that the conversion to carbon dioxide is favored by low temperatures. The reaction is through the so-called Boch temperature conversion catalysts, such as iron oxide / chromium oxide catalysts, which are generally effective in the temperature range of about 300 to about 600 ° C are, as well as by the so-called low-temperature shift catalysts, such as copper oxide / chromium oxide / zinc oxide catalysts or copper oxide / zinc oxide / aluminum oxide catalysts catalyzed, which occurs at lower temperatures, e.g.

operate in the range of about 175 to about 225 OC. Metals of Group VIII, such as nickel, are also effective as CO shift catalysts. Other conversion catalysts are the so-called medium-temperature conversion catalysts, the generally mixed cobalt and molybdenum oxides on a suitable carrier are. Figure it is recommended an operating temperature of about 280 to about 500 ° C.

When performing a CO conversion according to the invention, has the feed stream comprises a mixture of carbon monoxide and steam, the catalyst in the first and second reaction zone consists of a CO conversion catalyst, e.g. one of the above-mentioned shifting catalysts, and the first and second Temperature are at least as high as the light-off temperature of the CO conversion catalyst the first and the second reaction zone, respectively. When a low temperature shift catalyst is used, lies the first Temperature preferably in that Range from about 120 to about 300 ° C, the second temperature in the range of about 200 to about 350 ° C and the third temperature in the range of about 150 to about 300 ° C. When using a medium-temperature conversion catalyst is preferred the first temperature in the range from about 250 to about 400 OC, the second temperature preferably in the range from about 350 to about 500 ° C. and the third temperature preferably in the range of about 250 to about 400 ° C. When using a high temperature toning catalyst the first temperature is preferably in the range of about 300 to about 500 ° C, the second temperature in the range of about 400 to about 600 ° C, and the third Temperature in the range of about 300 to about 450 ° C. The operating pressure can be Atmospheric pressure or below or at elevated pressures. However, since the Response does not change in volume, results from working at increased Printing is not an advantage.

Any reversible exothermic gas phase catalytic reaction the values of the first, second and third temperature all depend on one another and on the gas composition at the entrance to the first reaction zone, the feed rate this gas, the size and shape of the reaction zones and the second and third Temperature of the coolant supply. As far as published thermodynamic If data are available for the reaction in question, a person skilled in the art can choose from them any value for any of these variables based on assumed values for determined the other variables.

In some cases it may be desirable to receive the first Feed stream fed to the reaction zone, e.g. about 0.1 to 10% or to add more gas from a point downstream of the second reaction zone is returned. Usually the amount of recycled gas exceeds not about 5% of the feed gas mixture.

The third temperature can be selected independently of the first temperature it is usually advantageous to keep the third temperature as low as possible to be chosen as far as the catalyst activity permits. As a result, the third Temperature can be greater than, equal to or less than the first temperature.

In either case, the feed gas for the first reaction zone contain any gaseous component in addition to the reactants that is not the desired reaction takes part in a significant way and not the catalyst activity destroyed or substantially reduced. These inert gaseous components can be present in variable amounts depending on the type of reaction.

In a typical case, an ammonia synthesis gas stream contains alongside the N2 and H2 up to about 15% by volume or more inert gases, such as methane, during a Feed gas stream for a methanation reactor in some cases up to 50% by volume or more inert gases such as methane.

A methanol synthesis gas, for example, can contain up to about 15% by volume or contain more inert components such as methane.

In the case of CO conversion, the percentage of not participating in the reaction participating ingredients in the feed gas of about 1% by volume or less up to 50% by volume or more of the feed gas stream. The origin of the The feed gas stream is insignificant as long as it has the desired reactants in sufficient concentration and proportion and essentially does not contain any interfering substances or substances that could poison the catalyst.

The second reaction zone can be a tubular reactor with one or more tubes filled with catalyst, each of which has an outer cooling jacket or they all have a common cooling jacket. Alternatively, the second Reaction zone consist of one or more catalyst beds in which in suitable Way cooling tubes are arranged.

The cooling takes place using a suitable coolant. Although in some cases a gaseous coolant, like air, Can apply, its heat capacity will usually not be sufficient to the desired course at the practical flow rates of the cooling gas to reach the Kühlkuve. Accordingly, one usually becomes a liquid refrigerant Select. So you can choose a vaporizable coolant such as Freon 12 or Freon 22, which at least partially evaporates with cooling of the second reaction zone. on In this way, part of the heat of reaction can be absorbed by evaporation of the coolant will. In one mode of operation, the coolant is consequently evaporable Liquid with an inlet temperature and a pressure at which it is liquid is introduced into a cooling zone located outside the second reaction zone and which is removed from the cooling zone at a temperature and under a pressure is, in which at least part of the coolant is vaporous, so that at least part of the heat of reaction as heat of evaporation from the second reaction zone is discharged.

In many cases, water is a suitable coolant; the refrigerator compartment can then be used as a waste heat boiler for the generation of low pressure steam for example 1.4 to 7 atmospheres, or high pressure steam of, for example, 7 to 105 atmospheres. Mercury can also be used as a vaporizable coolant; for cost reasons However, it is usually not used.

The invention also relates to a mode of operation in which the coolant enters the cooling zone located outside the second reaction zone and the Entry and exit temperature of the coolant and the pressure under which the Cooling zone is held, are chosen so that the coolant when passing through the cooling zone not evaporated. So can salts or salt mixtures, which at the reaction temperature melted, can be used as a coolant in certain cases. Examples of suitable ones Salts are the halides (e.g. chlorides and bromides) and nitrates of the alkali metals (e.g. sodium and potassium), alkaline earth metals (magnesium and calcium) and transition metals (e.g. zinc and copper) and mixtures of two or more of these salts. aside from that is it possible in certain cases to use substances such as Dowtherm, Diphenyl, Thermex (eutectic mixture of 26.5% diphenyl and 73.5% diphenyl oxide) and the like. In certain cases, liquid metals such as lead, Tin, sodium, mercury and the like can be used.

The coolant can be cocurrent or countercurrent to the gas flow flow through the second reaction zone. The cooling surface of the second reaction zone can be divided into two or more parts, each of which has its own Has coolant supply and each independently of the other part or parts like that is arranged that the coolant flows therein in cocurrent or countercurrent.

Although it is usually sufficient, a single initial reaction and Providing a single second reaction zone, it is possible in many cases that Process according to the invention twice or more times in succession with the gas stream perform on its gas flow path. In this case, two or more first reaction zones be provided, between each one of them and the or an adjacent first reaction zone, a suitable second reaction zone is arranged.

The invention is illustrated with reference to the accompanying schematic Drawing further explained. Figures 1 (a) and 1 (b) show a temperature / conversion diagram a typical exothermic catalytic gas phase reaction or a schematic Representation of the associated apparatus using the cold shot technique; figure 2 (a) and 2 (b) corresponding representations for a pseudoisothermal reactor with external evaporative cooling; FIG. 3 a temperature / conversion diagram for a pseudoisotherm Reactor with external cooling without evaporation; Figure 4 (a) shows a typical temperature / conversion curve for a method according to the present invention; Figure 4 (b) and 4 (c) other embodiments of the plant with which the curve of FIG. 4 (a) is obtained can; FIG. 5 shows a conventional embodiment of a methanol plant; Figure 6 a methanol plant which is operated according to the method according to the invention; figure 7 shows a conventional ammonia plant; FIG. 8 shows a diagram with equilibrium conversion curves in a range of temperatures and pressures in a single pass through one Methanol synthesis reactor using a stoichiometric feed gas (H2: CO 2: 1); FIG. 9 shows a diagram similar to FIG. 8 for the ammonia synthesis and FIG 10 is a diagram showing the temperature / conversion curves no. Three different interpretations of an ammonia tank shows.

Various reactors and other plant components were shown in the drawing simply shown schematically. A large number of different types of reactors are available known to the person skilled in the art and can be used according to the invention. For reasons of simplicity, valves and other system components, such as temperature sensors and pressure control systems are omitted. It is obvious to those skilled in the art that such additional plant components are necessary for the successful operation of the process, and the arrangement and use of these aids of the system are not part of the subject of the invention and correspond to normal chemical engineering practice.

In the drawing, FIG. 1 shows a typical cold gas quench cooling reactor with three beds. Relatively cold gas enters the system through line 10, and About 40% of the total gas flows through the heat exchanger 11 to the line 12 and enter the first catalyst bed 13, which is operated adiabatically. To Figure 1 (a) the temperature rises rapidly to point B. The gas leaves the Reactor as a mixture close to equilibrium, its temperature and composition are indicated in Figure 1 (a). If the first catalyst bed 13 were infinitely long, the gas mixture emerging from the catalyst bed 13 would correspond to point C in FIG 1 (a) have the appropriate temperature and composition. The more the reaction however, as it approaches point C, the slower the reaction speed becomes. Therefore the gas mixture leaving the adiabatic reactor 13 is a weight-bearing factor close mixture and not a fully equilibrated mixture.

The product gas from the reactor 13 is then with further relative cold gas from line 14 mixed. At the entry point D to the further one, too adiabatically operated, catalytic reactor 15 are the temperature and composition of the mixture as indicated by point D in Figure 1 (a). In in the reactor 15 the reaction continues and the temperature rises again towards the equilibrium point F indicated in FIG. 1 (a). As with the reactor 13 here too the reaction will not lead completely to equilibrium, so that the mixture exiting the reactor 15 has the composition and temperature, indicated by point E in Figure 1 (a). With the exit gas stream out Reactor 15 is mixed with further cold gas, which is supplied through line 16. The combined gas enters the third catalytic reactor. The temperature and the composition of the mixture at the inlet of the reactor 17 are shown in Figure 1 (a) indicated by the point G. The composition and temperature of the reactor 17 leaving gas mixture are indicated by the point H in Figure 1 (a).

Finally, the gas leaving the reactor 17, which is now a Temperature T 'has, through the heat exchanger 11, in which it is the temperature of the incoming Gas raises to the temperature T °.

When operating the system of Figure 1 (b), the temperature at the inlet to the first reactor 13, i.e. the temperature TO above the light-off temperature of the catalyst located in the reactor 13. In addition, she is allowed through the point B in Figure 1 (a) is the inactivation temperature of the Do not exceed the catalytic converter.

As can be seen from Figure 1 (a), points B, D, E, G and H a certain distance from the curve of maximum speed L-M. Hence runs essentially the entire reaction proceeds at sub-optimal rates, so that the catalyst is being used in a relatively ineffective manner.

An alternative to the cold shot system (or system with direct Quench cooling or direct quenching) is the so-called system with indirect Quench cooling, in which all the gas is passed through a series of adiabatic reactors flows alternately with indirect cooling between the adiabatic stages. In this Case will have a similar reaction profile as the line A-B-D-E-G-H of Figure 1 (a) obtained, however, in the case of indirect quench cooling, the lines B-D and lines corresponding to E-G of Figure 1 (a) are parallel to the temperature axis. Again, essentially all of the reaction occurs at different reaction rates than the optimum reaction speed represented by the line L-M.

In the cold shot system as well as in the system with indirect quench cooling a considerable number of beds is required to achieve a low outlet temperature and consequently to achieve a high percentage conversion of the desired product.

Figure 2 (a) shows the corresponding temperature / conversion curve for a in Figure 2 (b) shown pseudoisothermal reactor using a Constant temperature evaporation coolant. This coolant passes through Line 22 into the cooling jacket 20 surrounding the tube 21 filled with catalyst and exits through line 23. The inlet gas enters the reactor as indicated by arrow 24, and leaves the reactor at the opposite end, such as indicated by arrow 25. The refrigerant is an evaporative refrigerant, such as e.g. water, and its temperature in the cooling jacket is shown in Figure 2 (a) by the dashed line indicated at temperature T0. The temperature T0 represents the The light-off temperature of the catalytic converter is, and the temperature T1 is the inlet temperature when the catalyst is fresh. As can be seen from Figure 2 (a), the temperature rises except for the hot spot B and then falls again, so that when leaving the reactor a temperature and a composition corresponding to point C in Figure 2 (a) prevail. Again, a large part of the reaction proceeds under conditions far from line L-M maximum reaction speed are removed, so that the catalyst utilization is relatively ineffective. Furthermore, with a As the catalyst ages, employ a quench cooling, as indicated by the line A'-Q is specified.

Even if the inlet temperature is kept at T1, the Catalyst aging reason for an enlarged heat transfer area in the turnover unit, and it may be necessary to increase the feed temperature to reduce the loss to compensate for catalyst activity. If it doesn't, it is almost inevitably there will be a substantial decrease in product concentration. As the catalyst ages, the hot spot shifts the length of the catalyst bed down; this can lead to difficulties in the case of a satisfactory design of the reactor to lead.

These problems can to some extent through use a non-evaporable coolant can be overcome, as shown in FIG is. In this figure, countercurrent cooling is assumed, with the coolant inlet temperature with Xc 'and the coolant outlet temperature by 2 the temperature Tc and the Coolant temperature curve are indicated as a dashed line. However, it is still impossible to move the hot spot downwards in a satisfactory manner to calculate the catalyst bed in the course of the catalyst aging. As with the temperature profile of Figure 2 (a), the catalyst utilization is relatively ineffective because it is large part the reaction takes place away from the curve L-M of maximum reaction rate. This means that the reaction vessel must be enlarged accordingly.

Figure 4 (a) shows the temperature profile when working according to the invention Procedure. In this figure, TD means the inactivation temperature of the catalyst, T1 the temperature at the entrance to the first adiabatic reaction zone, T2 the second temperature or the exit temperature from the adiabatic part and T3 the temperature of the gaseous reaction mixture when it emerges from the externally cooled second reaction zone. T4 gives the coolant inlet temperature and the coolant outlet temperature at. The line L-M represents the maximum response speed curve and the line x-r represents the equilibrium curve.

Figures 4 (b) and 4 (c) indicate embodiments of the apparatus, with which curve A-3-C of Figure 4 (a) can be obtained. In Figure 4 (b) occurs the non-evaporating coolant through line 32 into the cooling jacket 30 of the with Catalyst-filled pipe 31 and exits the cooling jacket via line 33 the end. The inlet gas passes through line 34 into the first adiabatic reaction zone 35, exits through line 36 and flows to the inlet end of the catalyst-filled one Tube 31, which forms the second, externally cooled reaction zone. The product gas mixture exits through line 37.

The reactor of Figure 4 (c) is similar, with like parts also bear the same reference numbers. In this embodiment, however, the separate one adiabatic reaction vessel 35 of FIG. 4 (b) by an uncooled piece 38 of the pipe filled with catalyst replaced.

The devices of Figures 4 (b) and 4 (c) and the associated temperature profile of Figure 4 (a) offer over the pseudoisothermal reactor in several ways certain benefits regardless of whether you are using a non-evaporation coolant or an evaporation coolant begins. When using an uncooled adiabatic part, the second Temperature, i.e. the temperature at the exit from the adiabatic reaction zone, are precisely predetermined, so that a perfect protection temperature sensitive Catalysts is possible.

In addition, the temperature range in the adiabatic reaction zone, i.e. the difference between the second temperature T2 and the first temperature T1 can be selected independently of the third temperature T3. In the case of a pseudoisotherm Reactor with external evaporation or non-evaporation cooling can set the maximum temperature cannot be predetermined at the hot spot, which leads to difficulties in the design of the reactor leads.

It also causes a loss of coolant or a rise in coolant temperature in the case of a pseudoisothermal reactor, temperature excursions at the hot spot. At extremes In some cases, this can mean that the hot spot temperature is the inactivation temperature of Catalyst exceeds, whereby the catalyst activity can be lost.

In Figures 4 (b) and 4 (c), the tube is filled with catalyst shown as a single rectilinear reactor for simplicity. The pipe can have any desired, but usually circular, cross-section, and if so desired Spiral, U-shaped or bent in another shape.

Several parallel pipes can be used instead of a single pipe Find.

Figures 5 to 10 are further below in connection with the The following examples are described which illustrate the invention. The examples 1,4,6,8,11 and 14 are comparative examples and examples 2,3,5,7,9,10,12,13 and FIGS. 15 to 17 explain the method according to the invention.

Example 1 (comparative example) A conventional methanol plant is used at a pressure of 95 atmospheres using a cycle gas as follows operated according to volume composition: component percentage CH4 1.44 CO2 4.57 CO 16.02 H2 56.89 N2 21.08 This system is shown schematically in Figure 5 shown. It comprises 5 adiabatic reactors 121, 122, 123, 124 and 125 of suitable size, connected in series by lines 126, 127, 128 and 129 are. Each of the reactors 121 to 125 contains a common ethanol synthesis catalyst. The starting gas of bed 125 passes via line 130 to a flethanol recovery plant 131, from which methanol is drawn off via line 132 in an amount of 417 kmol / h. Unreacted gas is returned to the compression unit 134 through line 133, in which the pressure is increased back to the operating pressure. The administration 135 is used to replenish gas from a conventional synthesis gas system, and the line 136 is a gas discharge pipe through which inert components such as methane and nitrogen can be removed from the system.

The process gas is fed through line 137 via heating stage 138 to the input of the reactor 121 promoted. The inlet temperature at the inlet of the reactor 121 is 245 0C (that is a temperature above the light-off temperature of the catalytic converter).

Additional process gas is supplied via lines 139, 140, 141 and 142 fed according to the cold shot technique, so as to adjust the inlet temperature of the corresponding to reduce the following reactors and to enable further methanol synthesis.

Example 2 In this example, the system of FIG. 6 is used. This is generally similar to the system of Figure 5; it will - where applicable - the same reference numbers are used. The plant differs however, differs from that in FIG. 5 in that lines 139, 140, 141 and 142 have been omitted and the reactors 121, 122, 123, 124 and 125 by an adiabatic Reactor 151 and a waste heat boiler with a jacket 153, a cooling water inlet 154 and a steam outlet connection 155 designed reactor 152 are replaced. The composition of the circulating gas is the same as in Example 1, and the ethanol yield is also 417 kmol / h. The gas inlet temperature at the adiabatic reactor 151 is in this case 210 ° C. (again above the Light-off temperature of the catalyst), and the reactor 152 is operated so that the gas stream exiting the boiler 152 also has a temperature of 210.degree having. The outlet temperature of the reactor 151 is in the region of 280 to 290 0C. The operating pressure is only 33 atmospheres. This means that the compressors the compression stage 134 can be smaller and less energy than during operation Consume according to Example 1.

Example 3 The procedure of Example 1 is repeated, wherein however, the operating pressure is 95 atmospheres. In this case it decreases compared the amount of gas recirculated from the methanol separation stage 131 by 45% with Examples 1 and 2. Accordingly, the compressors of the compression stage 134 be smaller, and they consume less energy than when operating according to the example 1.

Example 4 (comparative example) The one shown in FIG. 7 is shown schematically shown system used. This has four reactors 161, 162, 163 and 164, of which Each contains an ammonia synthesis catalyst and is operated adiabatically, wherein between two adjacent reactors through lines 165, 166 and 167 gas introduced by the cold shot method. Inlet gas from a mixture of H2: N2 of about 3: 1 is fed through line 168 to compression stage 169, from where it reaches the heating stage 170 via line 171. The gas arrives at an inlet temperature of 520 0C (i.e. a temperature above the light-off temperature of the catalytic converter) and a pressure of 221 atmospheres via line 172 to reactor 161 and above the gas distributor 173 in the lines 165, 166 and 167. The gas injection after the Cold shot technology via lines 165, 166 and 167 enables the continuation the reaction in each of the subsequent reactors 162, 163 and 164. That is the reactor 164 leaving gas has the following volumetric composition constituent percentage CH4 13.54 N2 17.88 H2 52.40 NH3 16.18 It reaches an anonia separation stage 174, from which the azmo niac is withdrawn via line 175. Over line 176 is a repulsion taken to prevent the accumulation of non-reactive components, like methane, to avoid.

Example 5 A plant of the type shown schematically in FIG. 6 is used for the synthesis of ammonia. A gas mixture with an H2: N2 ratio of 3: 1 is introduced through line 135 and the ammonia separation stage 131 becomes withdrawn through line 132 ammonia. As in Examples 2 and 3, the reactor 151 operated adiabatically. The reactor 152 is circulating in cocurrent with a Cooled mixture of molten salts, available under the name Hitec (Hitec is a mixture of 50% NaN02 and 50 X Kr03).

Both reactors 151 and 152 contain a conventional ammonia synthesis catalyst. The system is operated with an inlet temperature at reactor 151 of 400 0C (a temperature above the light-off temperature of the catalyst) and with a gas outlet temperature driven at the reactor 152 of 450 ° C. The outlet temperature at reactor 151 is around 500 ° C. The operating pressure is 120 atmospheres.

The compressors of compression stage 134 and their energy consumption are therefore smaller than in the embodiment according to Example 4. The composition of the starting gas of the reactor 152 agrees with the starting gas composition of the Example 4 match.

Example 6 (comparative example) A methanol plant of the type shown in FIG The type shown is with a gas inlet temperature to the reactor 121 of 210 ° C and operated at a pressure of 50 atmospheres. The outlet temperature at the reactor 125 is 270 ° C. The gas circulation rate is 1 211 963 m3 / h with a rejection rate over line 136 of 6.52%. The methanol concentration in line 130 is 3.65%. In addition, synthesis gas (H2: CO 2: 1) is supplied through line 135 added at a rate of 182 062 m3 / h.

Example 7 A methanol plant of the type shown in Figure 6 is with operated at a gas circulation rate of 1 211 963 m3 / h. The inlet temperature to the reactor 151 is 210 dC, and the output temperature of this reactor is in the region of 280 to 290 00. The outlet temperature of the reactor 152 is 210 00. The reactor 152 is cooled with water and therefore functions as a waste heat boiler. The rejection rate through line 136 is 3.2% and the methanol content of the gas in line 130 at 3.65%. However, it is used to supplement synthesis gas (H2: CO 2: 1) added via line 135 at a rate of 144,990 m3 / h, a reduction of 20.4% compared to Example 6. This provides a significant saving the plant and operating costs of the synthesis gas plant, which the fortifying gas supplies.

Although the repulsion current is lower compared to Example 6 and consequently less exhaust gas is available as an energy source in the overall process is the cost of the additional fuel that is used to supplement the energy source serving repulsive current is required by reducing the operating costs of the synthesis gas plant more than balanced.

Figure 8 shows the percentage equilibrium conversion curves in one Temperature and pressure range for a single pass through a methanol synthesis reactor and using a stoichiometric feed gas (CO + 2 H2). These sales curves can be drawn from available thermodynamic data. With a conventional one Methanol plant is determined by the composition of the mixture leaving the reactor the outlet temperature is determined. If the catalyst bed is sufficiently large, the starting gas composition approaches the equilibrium composition at this temperature. However, when designing a methanol reactor, it is common assumed that the composition of the starting gas is the composition of a Equilibrium mixture at a slightly above the outlet temperature Temperature corresponds. This is how the gas emerging from a reactor at 260 ° C. can be used have approximately the composition of an equilibrium mixture at 288 ° C.

The method according to the invention essentially comprises a first adiabatic reaction stage, followed by an externally cooled reaction stage. If the process is used in a methanol plant with an externally cooled catalyst bed (or bed part) following an essentially adiabatically operated catalyst bed (or bed part) is used, the outlet temperature can be reduced.

Example 8 (comparative example) An adiabatic methanol reactor, which contains a conventional nethanol synthesis catalyst, is with a mixture charged from CO and H2 in a ratio of 1: 2 with an inlet temperature of 210 ° C. The outlet temperature is 260 ° C. and the pressure is 100 atmospheres. As As can be seen from FIG. 8, the percentage conversion of CO is approximately 50%, corresponding to an equilibrium temperature of 288 ° C.

Example 9 The reactor of Figure 4 (c) uses the same methanol synthesis catalyst filled as used in Example 8. The reactor is using the same CO: H2 mixture also charged with an inlet temperature of 210 ° C.

The maximum temperature reached in the adiabatic reaction zone 38 is in the range of about 282 to about 291 ° C, at which temperature the mixture in the second reaction Zone 31 enters. The outlet temperature the second reaction zone 31 is reduced to 204 ° C. in this case. The coolant is water, so that the second reaction zone acts as a waste heat boiler. From Figure 8 it can be seen that at an operating pressure of 100 atmospheres, the percentage CO conversion is increased to about 77% corresponding to an equilibrium temperature of 232 ° C.

Example 10 The procedure of Example 9 is at an operating pressure repeated from 33 atmospheres. A CO conversion of about 50% is achieved.

From Examples 9 and 10 it can be seen that the inventive Process can serve in the methanol synthesis compared to the usual, the procedure illustrated by Example 8 to increase the yield per pass or to reduce the operating pressure with the same conversion yield per pass. As a result the method according to the invention allows a reduction in the amount required for a maximization the number of reaction stages required for methanol production or it result reduced capital and operating costs for gas compression.

Figure 9 shows a similar series of percent equilibrium conversion curves in a temperature and pressure range for ammonia synthesis. In this case the feed gas is a mixture of H2 and N2 in proportion 3: 1.

These curves can also be obtained from published thermodynamic data be put together.

Example 11 (comparative example) An ammonia synthesis reactor is used adiabatically at a pressure of 220 atmospheres with a feed gas mixture operated by H2 and N2 in a ratio of 3: 1. The inlet temperature is 399 ° C and the outlet temperature is 482 ° C. The outlet gas corresponds to an equilibrium mixture at 510 0C. The conversion is 26 to 30%.

Example 12 In one with a conventional ammonia synthesis catalyst filled reactor of the type shown in Figure 4 (c) has the same inlet gas as in Example 11 under a pressure of 75 atmospheres and an inlet temperature used at 399 oC. The outlet temperature at the outlet end of the reactor is 399 ° C. corresponding to a 26 to 30 conversion of nitrogen to ammonia an equilibrium temperature of 427 0C. The coolant is the one mentioned above melted salt mixture Hitec. The coolant flows in cocurrent with the gas mixture. Alternatively, a countercurrent can also be used. The peak temperature reached is around 504 ° C.

Example 13 The procedure of Example 12 is with one print of 220 atmospheres and the same inlet and outlet temperatures. A conversion of nitrogen to ammonia of about 48% is achieved.

Comparing Example 11 with Example 12 or 13 is apparent that it is possible with the method according to the invention, either at the same conversion as with a conventional ammonia synthesis plant the operating pressure of the system or, with the same pressure, a higher conversion per pass to reach. In this way, the plant and operating costs for the gas compression reduced, or the return line with the associated auxiliary equipment can can be reduced in size.

Examples 14 and 15 These examples use carbon oxide conversion carried out catalytically on the one hand (Example 14) using a conventional one single-stage adiabatic converter and on the other hand (example 15) in a converter, of the type shown in Figure 4 (c). The catalyst is an iron oxide with chromium as a promoter. The results are summarized below: units Example 14 Example 15 (comparison) Gas velocity, wet Em3 / h 100 000 100 000 catalyst volume m3 46.3 37.0 inlet temperature ° C 340 400 outlet temperature 0c 510 400 In Example 15, that reached in the adiabatic reaction zone 38 is Maximum temperature 516.5 ° C. The outlet temperature given in the table is the temperature of the exit from zone 31.

In each case, the inlet and outlet gas compositions are as follows: inlet (mol%) outlet (mol-j6) inert components 0.750 0.750 CO2 1.903 17.843 CO 20.290 4.350 H2 17.870 33.770 H20 59.187 43.287 The with the invention Achievable savings in catalyst volume are from the above to the method Results presented in Examples 14 and 15 are apparent. It is also to be expected that the catalyst at the downstream end of the reactor used in Example 15 a longer service life than the catalyst at the downstream end of the corresponding reactor from Example 14 because it has a lower temperature Example 16 In this example Synthetic natural gas SNG is produced by making a synthesis gas of the following Composition% by volume CH4 0.434 CO 24.822 H2 74.466 N2 0.278 by an adiabatic Sends reactor containing a nickel methanation catalyst. The inlet temperature is 520 0C and the inlet pressure is 68 atmospheres. The one emerging from the reactor Gas is essentially in equilibrium, has a temperature of 950 0C and contains 9.3% by volume methane. This gas then becomes one with the same catalyst Filled, externally cooled reactor (e.g. one equipped with a waste heat boiler Tubular reactor) fed.

The coolant flow can be countercurrent or cocurrent. The outlet temperature is 280 ° C. The product gas contains 95.11% methane and has a calorific value of 8450 kcal / Nm3.

Example 17 (a) A feed gas for anonia synthesis with a Volume ratio H2: N2 of 3: 1 and a low concentration at Inert components (less than 0.5% by volume) and with a content of about 3% by volume recycled ammonia is a conventional reactor with 212 atmospheres direct quench cooling and three adiabatic stages with cold gas injection between fed to the stages. The inlet temperature to the first stage is around 400 ° C. The exit gas from the third adiabatic stage is at about 490 ° C and contains 16.5% ammonia. The temperature / concentration curve is shown in Figure 10 as line A-A shown. Lines D-D and E-E are the equilibrium curve and the curve of maximal, respectively Reaction speed.

(b) The same feed gas as in the previous section (a) is using a two-stage converter with indirect at 360 ° C and 212 atmospheres Quench cooling fed.

The outlet temperature is again 490 ° C and the ammonia concentration 17.5%. The temperature / concentration curve is shown in Figure 10 as line B-B. The catalyst volume is the same as the direct quench reactor of the previous paragraph (a).

(c) The same feed gas as in paragraphs (a) above and (b) at 420 ° C and 212 atmospheres becomes one with a plurality of tubes equipped reactor of the type shown in Figure 4 (c) with cocurrent salt cooling (using Hitec's molten salt mixture).

The temperature at the exit from the uncooled adiabatic zone 38 is about 510 ° C. The hot spot is located in the second cooled reaction zone 31 at around 520 ° C. The outlet temperature at the downstream end of the cooled reaction zone 31 is 460 ° C, producing an ammonia concentration of 20.0%. the The temperature / concentration curve is line C-C in Figure 10. The catalyst volume is the same as the direct and indirect quench cooling reactors in accordance with paragraphs (b) and (c) above.

These results are summarized in the following table: Table Pressure Percent NR in the gases at the 3 exit (a) R Conventional converter ata sen Reactor with direct quench cooling (Cold Shot) 212 16.5 (b) Converter with indirect Quench Cooling 212 17.5 (c) Converter 212 According to the Invention 212 20.0 Accordingly it can be seen that the conversion per pass in the procedure according to the invention can be increased by at least 2.5% compared to the current technical Reactor designs assuming the same catalyst content in each Case.

Claims (7)

Claims 1. A method for performing a reversible exothermic Gas phase reaction in which a feed stream with one or more gaseous Reactants exothermic and reversible in one or more, one the exothermic reaction catalyzing catalyst containing reaction zones to form one or more gaseous products reacts, characterized in that the Supplies feed stream at a first temperature to a first reaction zone, react in this under essentially adiabatic reaction conditions and allows a second temperature to be reached which is higher than the first temperature, However, below the inactivation temperature of the catalyst, the resulting Gas mixture then essentially at the second temperature of a second externally cooled one Reaction zone feeds the heat of reaction from the gas stream as it passes through discharges continuously through the second reaction zone and the product mixture with a third temperature from the second reaction zone which is below the second temperature withdraws. 2. The method according to claim 1, characterized in that the gaseous Feed stream contains a gas portion, from one place was returned on the offshoot side of the second reaction zone. 3. The method according to claim 1 or 2, characterized in that the third temperature is chosen to be equal to or lower than the first temperature. 4. The method according to any one of claims 1 to 3, characterized in that that the feed stream contains a mixture of nitrogen and hydrogen and the catalyst of the first and second reaction zones is an ammonia synthesis catalyst is. 5. The method according to any one of claims 1 to 3, characterized in that that the feed stream contains a mixture of hydrogen and carbon monoxide and the catalyst of the first and second reaction zones is an ethano1 synthesis catalyst is. 6. The method according to any one of claims 1 to 3, characterized in that that the feed stream is a mixture of one or more carbon oxides and hydrogen and the catalyst of the first and second reaction zones is a methanation catalyst is. 7. The method according to any one of claims 1 to 3, characterized in that that the feed stream contains a mixture of carbon monoxide and water vapor, the catalyst of the first and second reaction zones is a CO converting catalyst and the first and second temperatures are at least as high as the light-off temperature of the CO conversion catalyst of the first and second reaction zones, respectively.