DE102016221967A1 - Process for the production of ammonia and ammonia synthesis converter - Google Patents

Abstract

The present invention relates to a process for the preparation of ammonia in an ammonia synthesis converter, in which one passes a Eduktgasstrom first through a first catalyst bed (16), in which a reaction of the educt gases takes place, the first catalyst bed is associated with a heat exchanger (17) and one then passes the process gas stream through a second catalyst bed (20), in which a further reaction of the educt gases takes place, the second catalyst bed is associated with a further heat exchanger (19), wherein the Eduktgasstrom the ammonia synthesis converter in at least two partial streams via separate inlets (11 , 18) in order to influence the temperature of the process gas streams in the ammonia synthesis converter and wherein at least a partial flow of the educt gases can flow as a cooling medium through one of the heat exchangers to heat exchange with a heat exchanger flowing through the reaction heated Prozes to effect gas flow, and wherein according to the invention the process gas stream flowing out of the second catalyst bed (20) then passes through a third catalyst bed (26). The present invention furthermore relates to an ammonia synthesis converter (10) which is used in the aforementioned method. Preference is given to using each space-saving plate heat exchanger, which require a smaller volume at the given heat output and make it possible to use the freed volume for additional catalyst and thus to increase production.

Description

The present invention relates to a process for the preparation of ammonia in an ammonia synthesis converter, in which one passes a Eduktgasstrom first through a first catalyst bed in which a reaction of educt gases takes place, the first catalyst bed is associated with a heat exchanger and then the process gas stream through a second Catalyst bed passes, in which a further reaction of the educt gases takes place, wherein the second catalyst bed is associated with a further heat exchanger, wherein the Eduktgasstrom the ammonia synthesis converter in at least two partial streams via separate inlets to influence the temperature of the process gas streams in the ammonia synthesis converter and wherein at least a partial flow of educt gases can flow as a cooling medium through one of the heat exchangers to effect a heat exchange with a process gas flow through the reaction flowing through the heat exchanger. The present invention furthermore relates to an ammonia synthesis converter which is suitable for the production of ammonia by the abovementioned process.

The volumes of the pressure vessels for ammonia synthesis reactor are divided in principle on the claimed by the catalyst beds, the heat exchangers and the gas channels partial volumes. Due to the generally relatively high working pressures of the synthesis reactors, the pressure vessels are expensive components. A minimization of the specifically correspondingly expensive pressure vessel volumes is therefore generally desirable.

From the US patent US 7,780,925 B2 is a catalytic fixed bed reactor for heterogeneous catalytic reactions known, which is also used for ammonia synthesis, among others. The reactor described therein comprises a first catalyst bed in which a heat exchanger is arranged, which is designed as a plate heat exchanger. Below the first catalyst bed, a second catalyst bed is arranged with a second plate heat exchanger. In its upper region, this reactor has a taper in diameter, so that a kind of bottleneck is formed. In this tapered upper area, a third heat exchanger is arranged, but this is a shell and tube heat exchanger. The chemical reaction takes place here in only two catalyst beds.

In situations where it is necessary to replace the converter inserts because the life limit has been reached, an increase in the capacity of the system is often desired. Ammonia synthesis converter, as shown in the aforementioned U.S. Patent 7,780,925 B2 are known to have a bottle-like shape with a reduced diameter access to the head so that you can not replace the converter insert as a whole unit. An increase in the catalyst volume in this type of converter is difficult because it would require welding within the converter. These welding operations would be extremely risky because the inserts in the converters were in continuous operation for long periods of time in a highly nitriding atmosphere. In addition, a conversion of the converter operation would lead to a longer downtime of the plant and thus to a significant loss of production, which would jeopardize the overall economic viability of the equipment ("revamp") of the plant. In order for a conversion concept of a plant to remain economical, one should refrain from major conversion work within the converter as well as longer and complicated welding work.

Another disadvantage of these converters, on which measures have already been often carried out to increase the capacity, that the already high pressure loss makes a further increase in the amount of process gas impossible.

The tube bundle heat exchangers used in ammonia synthesis converters require a relatively large volume per transferred heat output (low heat flow density), so that less volume is available for the catalyst bed. A heat exchanger that requires less volume at the given heat output makes it possible to use the freed volume for additional catalyst to increase production. On the other hand, if it is possible to reduce the pressure loss of the heat exchanger at the same volume, one can achieve the capacity increase solely by increasing the amount of gas and thus without increasing the catalyst volume.

Due to the nature of the specific heat transfer performance of shell and tube heat exchangers is limited and is of other types such. Plate heat exchangers clearly exceeded. In contrast to shell and tube heat exchangers, however, plate heat exchangers are limited to approximately 20 bar with regard to the permissible pressure difference between the two material streams. Since the pressure difference when using the plate heat exchanger in an ammonia synthesis converter of the type described here is limited to the pressure losses in the catalyst beds and flow channels and is below about 5 bar, the use of plate heat exchangers is basically possible.

Standard plate heat exchangers are usually made with a plurality of parallel rectangular ones Plates with four supply pipes (two each for cold and warm electricity). The plates are not flat, but have a complex undulating shape, usually in herringbone pattern to increase the heat transfer surface and to improve the heat transfer through higher turbulence and to ensure the mechanical support of the usually quite thin plates with each other. Less common, but basically known, are round plate heat exchangers.

The object of the present invention is to provide a process for the production of ammonia in an ammonia synthesis converter having the features of the aforementioned type, in which a comparable increase in capacity can be achieved over known converters with a comparable volume of converter. The object of the invention is also to provide an ammonia synthesis converter suitable for this process.

The solution of the aforementioned object provides a method of the type mentioned above with the features of claim 1 and an ammonia synthesis converter with the features of claim 12.

According to the invention, the process gas stream flowing out of the second catalyst bed is subsequently passed through a third catalyst bed.

A preferred further development of the task solution according to the invention provides that the educt gas stream is preheated in a third heat exchanger before the educt gas stream is passed through the first catalyst bed, the third heat exchanger being designed as a plate heat exchanger. This makes it possible to accommodate an effective and space-saving plate heat exchanger in the tapered head region of the ammonia synthesis converter, in which only a reduced space available.

It is advantageous in the context of the present invention, the use of particularly space-saving round plate heat exchanger with direct lateral inflow of the hot gas, as for example in the not previously published earlier application DE 2016 114 713.3 from 09. 08. 2016 are described. These space-saving plate heat exchangers fill the entire available volume, so that the pressure loss can be significantly reduced by increasing the distances between the individual plates. It should be noted here that the pressure loss in the heat exchangers usually accounts for the majority of the total pressure loss in the ammonia converter use. With reduced pressure loss, the feed amount (amount of the feed stream) can be increased, which although the ammonia discharge concentration lowers, but increased by the total larger amount of gas, the absolute amount of synthesized ammonia. Although the pressure loss increases by increasing the amount of gas, but remains well below the critical values.

The plate heat exchangers used in the present invention are preferably particularly space-saving round heat exchangers of the aforementioned type. These have the advantage that the process gas stream can first completely flow through the first catalyst bed substantially in the radial direction and then the first heat exchanger associated with this catalyst bed flows through. The plate heat exchanger thus does not reduce the volume of the catalyst bed, since it does not protrude into the catalyst bed, as in the prior art, but is arranged concentrically radially inwardly to the catalyst bed, so that the catalyst bed surrounds the heat exchanger on the outside ring.

According to a preferred development of the present invention, it is accordingly provided that the process gas stream first flows through the second catalyst bed substantially completely in the radial direction and then flows through a second heat exchanger assigned to this catalyst bed.

According to a preferred development of the present invention, the process gas stream flows into the first and / or the second heat exchanger essentially in the radial direction and flows out of the respective heat exchanger in the axial direction. This is possible by a specific compact and space-saving design of the plate heat exchanger. Substantially axially out of the first heat exchanger effluent process gas, for example, in a space between the first catalyst bed and the second catalyst bed again flow radially outward, so that the process gas stream then enters the second catalyst bed again from radially outside and flows through this from outside to inside, thereafter to flow through the second heat exchanger after heating by the reaction in the catalyst bed.

According to a preferred development of the process according to the invention, a first educt gas stream, which constitutes a main gas stream of the educt gases, in a lower region through a first inlet to the ammonia synthesis converter, then guides this main gas stream upwards in the ammonia synthesis converter in a radially outer region, then passes it through the third heat exchanger and so warms him and then leads him to the first catalyst bed.

Furthermore, it is preferred to introduce a second educt gas stream, which represents a smaller partial gas stream of the educt gases compared to the main gas stream, to the ammonia synthesis converter in a central region through a second inlet, then directs it in the ammonia synthesis converter as coolant through the second heat exchanger, warming it up and leading it then him to the first catalyst bed.

Furthermore, it is preferable to introduce a third reactant gas stream, which represents a smaller partial gas stream of the educt gases compared to the main gas stream, to the ammonia synthesis converter in an upper region through a third inlet, then conduct it in the ammonia synthesis converter as coolant through the first heat exchanger, thus heating and leading it then him to the first catalyst bed.

In this way, it is preferred to introduce at least three different partial streams of educt gases into the ammonia synthesis converter in three different regions and to pass all three partial streams of the educt gases first through the first catalyst bed, then through the second catalyst bed and then through the third catalyst bed, so that all partial streams each participate in the reaction in all three catalyst beds.

Due to its specific current flow of the process gas stream in the ammonia converter, the abovementioned preferred solution according to the invention has a further advantage over previously known approaches, in which a comparatively large proportion of the cold educt gases (for example of the order of about 25% of the total feed gas stream) for cooling the product gas after first catalyst bed is used by direct admixture (so-called quench). This has the consequence that the product gas formed by reaction in the first catalyst bed is diluted by the supplied fresh quench gas stream. The solution according to the invention makes it possible to significantly reduce this proportion of quenching gas. The fresh educt gases introduced as the main stream into the ammonia synthesis converter are now first indirectly preheated in a heat exchanger and after mixing with the "cold" substreams, which are also each passed through a heat exchanger, the combined process gas stream is fed to the first catalyst bed.

A further preferred embodiment of the method according to the invention provides that a partial gas stream, which is passed as a coolant through the second heat exchanger, then passes through the outlet ports of the heat exchange fluid of the first heat exchanger and combined with the flow of the exiting heat exchange fluid of the first heat exchanger. This measure saves space for additional supply lines and also improves the mixing of the partial streams before the entry of the educt gas stream into the first catalyst bed.

The present invention furthermore relates to an ammonia synthesis converter comprising a pressure vessel, a first annular catalyst bed in this pressure vessel and at least one first heat exchanger associated with this catalyst bed in the region between the first catalyst bed and an inner wall of the pressure vessel, further comprising a second annular catalyst bed in said pressure vessel and at least one second heat exchanger associated with this catalyst bed in the region between the second catalyst bed and an inner wall of the pressure vessel, wherein the first and the second heat exchanger are each formed as a plate heat exchanger, wherein at least a third heat exchanger is provided, which in the flow direction of the Eduktgasstroms flowing into the pressure vessel is seen upstream of the first catalyst bed and wherein according to the invention, the third heat exchanger as a plate heat auscher is formed.

Preferably, the ammonia synthesis converter comprises a third catalyst bed, which is connected downstream of the second catalyst bed and the second heat exchanger in the flow path of the process gas stream.

This third catalyst bed preferably extends further in the ammonia synthesis converter radially inward than the other two catalyst beds. In particular, no further heat exchanger is provided at the level of the third catalyst bed, so that the radial extent of the third catalyst bed can reach almost to the center of the container and thus this catalyst bed can have a larger volume. Cooling to some extent, however, the product gases exiting from the third catalyst bed, if they are, as preferred in the process according to the invention, passed before flowing out of the converter through the third plate heat exchanger, in countercurrent to the incoming main gas stream of educt gases preheated here become.

Preferably, the inlet for the educt gas stream is arranged in the lower region of the pressure vessel and the third heat exchanger is arranged in the upper region of the pressure vessel above the first catalyst bed. In this conception, the educt gases entering the converter are first led upwards outside the reactor space in the converter and then flow off above by the provided there third plate heat exchanger before they enter the first catalyst bed.

Preferably, the second catalyst bed is disposed in the pressure vessel below the first catalyst bed, and the third catalyst bed is in turn disposed below the second catalyst bed and at the bottom of the vessel.

Preferably, an axial central pipe or an axial central piping system is arranged in the container, in which the product gas stream flows in from the bottom after passing through the third catalyst bed and which has an outlet for a product gas stream in the upper region of the container. The container has a compact design. The educt gas (or its main stream) flowing in at the bottom first flows upwards outside the catalyst beds, then flows through all three catalyst beds from top to bottom in the interior and then undergoes a flow diversion and flows through an approximately central pipeline from bottom to top, where it exits exits the converter.

The aforementioned axial central pipeline for the product gas stream is then passed through the third heat exchanger in the upper region of the converter and in its outflow region before it exits the converter.

A preferred constructional embodiment of the ammonia synthesis converter according to the invention provides that the third heat exchanger is arranged in an upper region, narrowed in cross-section, of the pressure vessel. This cross-sectional constriction is present in certain converter types and can be used according to the invention for the accommodation of the third plate heat exchanger. The catalyst beds, of which the first and the second preferably in each case surround a plate heat exchanger annular, so are at the same axial height in the container as each associated with a plate heat exchanger, require more space and are therefore located in the region located below the cross-sectional constriction of the converter, in which the converter has a larger cross-section.

• 1 eine schematisch vereinfachte Darstellung eines Längsschnitts durch eine Hälfte eines erfindungsgemäßen Ammoniaksynthesekonverters.

Hereinafter, the present invention will be described with reference to an embodiment with reference to the accompanying drawings. Showing:

• 1 a schematically simplified representation of a longitudinal section through one half of an ammonia synthesis according to the invention.

The following is first referring to 1 the basic structure of an inventive Ammoniaksynthesekonverters explained, which in total by the reference numeral 10 is named. In the drawing according to 1 is essentially only the left half of the ammonia synthesis converter 10 shown. This comprises a pressure vessel, in which via an inlet 11 in the lower region of the pressure vessel, a main stream of the educt gases nitrogen and hydrogen are introduced, which are converted in the ammonia synthesis converter according to the Haber-Bosch process to ammonia gas. This main flow of educt gases flows in the pressure vessel initially in a radially outer channel 12 in the direction of the arrows 13 upwards. In its uppermost section, the ammonia synthesis converter 10 a tapered head area 14 which has a reduced diameter compared to the entire underlying area. In this tapered head area 14 is a third plate heat exchanger 15 arranged, which flows through the incoming cold educt gas from top to bottom, wherein the Eduktgasstrom by countercurrently through this plate heat exchanger 15 Pre-heated flowing exiting hot product gas. The preheated Eduktgasstrom then flows after direction reversal from top to bottom in the interior of the ammonia synthesis converter, wherein the Eduktgasstrom is initially passed in the upper region radially outward, then into a first catalyst bed 16 enter. This first catalyst bed 16 flows through the educt gas stream from radially outside to radially inside. In this catalyst bed, the reaction of the educt gases nitrogen and hydrogen to ammonia gas takes place, which usually does not complete conversion, so that the resulting product gas stream also contains portions of the educt gases.

After flowing through the first catalyst bed 16 In approximately horizontal flow from radially outside to radially inside, the process gas stream heated due to the exothermic reaction enters a first plate heat exchanger 17 where cooling takes place by means of a cooling gas stream which flows through the first plate heat exchanger in cocurrent (or optionally alternatively in countercurrent) to the process gas stream. In this cooling gas stream is a supplied from the outside smaller partial flow of educt gases, which via a supply line 18 the first plate heat exchanger 17 is supplied. Relative to the main gas flow passing through the lower inlet 11 enters the ammonia synthesis converter, it is the partial flow through the supply line 18 by a percentage lower proportion of the total of the ammonia synthesis converter 10 fed educt gases. An advantage of the present invention, however, is that this second lower Partial flow also on the reaction in the first catalyst bed 16 participates. This is achieved by passing this partial flow after passing through the first plate heat exchanger 17 radially inward in the direction of the arrows in approximately axial flow leads upwards, then over the first plate heat exchanger 17 mixed with the incoming from above main gas stream of educt gases and radially outward passes, where the resulting total flow from radially outside the first catalyst bed 16 flows through. By this measure, on the one hand, a higher yield of product gas is achieved and at the same time a cooling of the by the reaction in the first catalyst bed 16 achieved process gas achieved.

The first plate heat exchanger 17 is concentric with the first catalyst bed 16 arranged so that it is surrounded by the annular first catalyst bed annular. In the ammonia synthesis converter according to the invention 10 used plate heat exchangers are particularly space-saving constructions with direct lateral inflow of the hot gas, which fill the entire available volume in the container and have a high specific heat transfer performance. Below the first plate heat exchanger 17 is a correspondingly designed second plate heat exchanger 19 arranged. Furthermore, it is located below the first catalyst bed 16 in the ammonia synthesis converter 10 a second catalyst bed 20 which in turn is the second plate heat exchanger 19 The outer ring concentrically surrounds.

The process gas leaves after the reaction in the first catalyst bed 16 and after flowing through the first plate heat exchanger 17 down and then flows above the second catalyst bed 20 in the direction of the arrow 21 radially outward and then enters from radially outward into the second catalyst bed 20 in which a reaction to ammonia gas occurs again. After flowing through the second catalyst bed 20 the heated process gas stream passes from radially outside into the second plate heat exchanger 19 and flows through this radially inward in an approximately horizontal flow, with a cooling of the previously heated by the reaction process gas takes place. For cooling in this second plate heat exchanger 19 Another cool partial gas flow of educt gas is used, which via a supply line 22 flows from the outside into the ammonia synthesis converter and then at the bottom in the second plate heat exchanger 19 initially flows in vertically and then after deflection horizontally this second plate heat exchanger 19 in cocurrent (or alternatively, if appropriate, in countercurrent) to the hot process gas from the second catalyst bed 20 flows through and then radially inside in an approximately axial direction at the second plate heat exchanger 19 and on the first plate heat exchanger 17 flows upwards.

Here one recognizes a further advantage of the flow guidance according to the invention of the partial flows, since the cooling partial flow from the supply line 22 passing through the second plate heat exchanger 19 flows axially upward in the central area of the converter and then directly through the ports of the first plate heat exchanger 17 flows and with the first plate heat exchanger leaving the partial flow from the supply line 18 mixed. This combined process gas stream flows above the first plate heat exchanger 17 in the direction of the arrow 23 radially outward and then mixes with the incoming from above main stream of educt gas, so that all three partial streams after union then the first catalyst bed 16 from outside to inside and from the reaction in the first catalyst bed 16 take part. Also, the partial flow through the supply line 22 occurs, thus fulfilling an additional function, namely the cooling of the hot process gases in the second plate heat exchanger 19 after the reaction in the second catalyst bed 20 , Nevertheless, this partial stream is not lost in the conversion to ammonia gas, but participates in the reaction in all three catalyst beds, whereby the overall yield of the reaction is further increased.

The process gas stream after the reaction in the second catalyst bed 20 from the second plate heat exchanger 19 flows vertically downwards, then flows in a gap 24 in the direction of the arrow 25 radially outward and then enters from the outside in a third catalyst bed 26 in order to then flow through this radially inward. This third catalyst bed 26 is arranged in the lower region of the pressure vessel and thus below the second catalyst bed 20 but with the third catalyst bed 26 unlike the second catalyst bed 20 extends annularly further radially inward because inside no plate heat exchanger is arranged for this. After flowing through the third catalyst bed 26 the product gas exits at this radially inside and then flows in the direction of the arrows 27 axially upward, and then in a centrally axially arranged in the ammonia synthesis converter flow channel 28 to flow vertically upwards. In the upper end of the ammonia synthesis converter 10 The hot product gas then flows through the third plate heat exchanger approximately vertically from bottom to top 15 who is in the rejuvenated head area 14 of the ammonia synthesis converter 10 located. Thus, this hot product gas before it leaves the pressure vessel flows in the third plate heat exchanger in countercurrent to that in the Pressure vessel inflowing cold main flow of educt gas and heats this.

LIST OF REFERENCE NUMBERS

10

Ammonia synthesis converter

11

Inlet below

12

channel

13

arrows

14

tapered head area

15

third plate heat exchanger

16

first catalyst bed

17

first plate heat exchanger

18

supply

19

second plate heat exchanger

20

second catalyst bed

21

arrow

22

supply

23

arrow

24

gap

25

arrow

26

third catalyst bed

27

arrow

28

central flow channel

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7780925 B2 [0003, 0004]
• DE 2016114713 [0013]

Claims (19)

Process for the preparation of ammonia in an ammonia synthesis converter (10), in which a feed gas stream first passes through a first catalyst bed (16), in which a reaction of the educt gases takes place, the first catalyst bed is associated with a heat exchanger (17) and then the Process gas stream passes through a second catalyst bed (20), in which a further reaction of the educt gases takes place, the second catalyst bed is associated with a further heat exchanger (19), wherein the Eduktgasstrom the ammonia synthesis converter in at least two partial streams via separate inlets supplies to the Temperature of the process gas streams in the ammonia synthesis converter to influence and wherein at least a partial stream of educt gases as cooling medium flow through one of the heat exchangers to effect an indirect heat exchange with a heat exchanger flowing through the reaction heated process gas stream before the this partial stream is combined with another or possibly several other partial streams of the educt gases, characterized in that the process gas stream flowing out of the heat exchanger (19) to the second catalyst bed (20) is subsequently passed through a third catalyst bed (26). Process for the production of ammonia in an ammonia synthesis converter according to Claim 1 , characterized in that preheating a Eduktgasstrom in a third heat exchanger (15) before the Eduktgasstrom is passed through the first catalyst bed (16), wherein the third heat exchanger (15) is designed as a plate heat exchanger. Process for the production of ammonia in an ammonia synthesis converter according to Claim 1 or 2 , characterized in that the process gas stream first flows through the first catalyst bed (16) substantially completely in the radial direction and then flows through a first heat exchanger (17) assigned to this catalyst bed. Process for the production of ammonia in an ammonia synthesis converter according to Claim 3 , characterized in that the process gas stream flows into the first heat exchanger (17) substantially in the radial direction and flows out in the axial direction from the first heat exchanger (17). Process for the production of ammonia in an ammonia synthesis converter according to one of the Claims 1 to 4 , characterized in that the process gas stream first flows through the second catalyst bed (20) substantially completely in the radial direction and then flows through a second heat exchanger (19) assigned to this catalyst bed. Process for the production of ammonia in an ammonia synthesis converter according to one of the Claims 1 to 5 , characterized in that the process gas stream flows into the second heat exchanger (19) essentially in the radial direction and flows out in the axial direction from the second heat exchanger (19). Process for the production of ammonia in an ammonia synthesis converter according to one of the Claims 2 to 6 characterized in that a first feed gas stream, which is a main gas stream of educt gases, is fed to the ammonia synthesis converter (10) in a lower region through a first inlet (11), then upwardly in a radially outer region in the ammonia synthesis converter, then through the third heat exchanger (15) passes and preheats and then the first catalyst bed (16) feeds. Process for the production of ammonia in an ammonia synthesis converter according to one of the Claims 1 to 7 , characterized in that a second reactant gas stream, which represents a lower partial gas stream of the educt gases compared to the main gas stream, in a central region through a second inlet (22) the ammonia synthesis converter (10), then in the ammonia synthesis converter as a coolant through the second heat exchanger ( 19) conducts and preheats and then the first catalyst bed (16) feeds. Process for the production of ammonia in an ammonia synthesis converter according to one of the Claims 1 to 8th , characterized in that a third Eduktgasstrom, which represents a lower compared to the main gas flow partial gas flow of educt gases in an upper region through a third inlet (18) the ammonia synthesis converter (10), then in the ammonia synthesis converter as a coolant through the first heat exchanger ( 17) and preheats and then the first catalyst bed (16) feeds. Method according to Claim 9 characterized in that one passes all three partial streams of the educt gases first through the first catalyst bed (16), then through the second catalyst bed (20) and then through the third catalyst bed (26). Method according to one of Claims 8 to 10 , characterized in that one passes a partial gas flow, which is passed as a coolant through the second heat exchanger (19), then through the outlet ports of the heat exchange fluid of the first heat exchanger (17) and with the flow of exiting heat exchange fluid of the first heat exchanger (17) united. Ammonia synthesis converter comprising a pressure vessel, a first annular catalyst bed formed in this pressure vessel and at least one first associated with this catalyst bed heat exchanger in the region between the first catalyst bed and an inner wall of the pressure vessel, further comprising a second annular catalyst bed formed in this pressure vessel and at least one second associated with this catalyst bed Heat exchangers in the region between the second catalyst bed and an inner wall of the pressure vessel, wherein the first and the second heat exchanger are each formed as a plate heat exchanger, wherein at least a third heat exchanger is provided, which is seen upstream of the first catalyst bed in the flow direction of the educt gas stream flowing into the pressure vessel, characterized in that the third heat exchanger (15) is designed as a plate heat exchanger. Ammonia synthesis converter after Claim 12 , characterized in that it comprises a third catalyst bed (26), which is connected downstream of the second catalyst bed (20) and the second heat exchanger (19) in the flow path of the process gas stream. Ammonia synthesis converter according to one of Claims 12 or 13 , characterized in that the inlet (11) is arranged for the Eduktgasstrom in the lower region of the pressure vessel and the third heat exchanger (15) in the upper region of the pressure vessel above the first catalyst bed (16) is arranged. Ammonia synthesis converter according to one of Claims 12 to 14 characterized in that the second catalyst bed (20) is disposed in the pressure vessel below the first catalyst bed (16) and the third catalyst bed (26) is located below the second catalyst bed (20) and at the bottom of the vessel. Ammonia synthesis converter according to one of Claims 12 to 15 characterized in that an axial central conduit (28) or an axial central conduit system is disposed in the vessel into which the product gas stream, after passing through the third catalyst bed (26), flows from below and which provides an outlet for a product gas stream in the upper region of the Container has. Ammonia synthesis converter after Claim 16 , characterized in that the axial central pipe (28) for the product gas stream in its outflow region is passed through the third heat exchanger (15). Ammonia synthesis converter according to one of Claims 12 to 17 , characterized in that the third heat exchanger (15) is arranged in an upper narrowed in cross-section region of the pressure vessel. Ammonia synthesis converter according to one of Claims 12 to 18 characterized in that the third catalyst bed (26) extends radially further toward the center of the container than the first catalyst bed (16) and / or the second catalyst bed (20).

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