DE102017204208A1 - Process and plant for the production and preparation of a synthesis gas mixture - Google Patents

Abstract

The present invention relates to a process for the production and preparation of a synthesis gas mixture for the production of ammonia, in which a hydrocarbon and steam-containing starting gas mixture is converted in an autothermal reformer (49) by means of oxygen in a Rohsynthesegasgemisch, which after further processing at least one ammonia synthesis (15, 45) is fed, in which according to the invention only a partial stream (48) of the starting gas mixture to the autothermal reformer (49) supplies while a further partial stream (32) of the starting gas mixture a primary reformer (33) and then the secondary reformer (20) feeds and the gas mixture produced in these primary and secondary reformers optionally after further treatment also an ammonia synthesis (15, 45), wherein a final nitrogen addition takes place immediately prior to synthesis and wherein the nitrogen is pumped or compressed to the synthesis pressure. An advantage of this method is that a massive relief of all process units between the secondary reformer and the main synthesis is achieved, including the process air compressor and the synthesis gas compressor. Compared to a variant with only one autothermal reformer, among other advantages, for example, an advantage of the combination according to the invention with the primary reformer is that the heat in the flue gas channel of the primary reformer can be used.

Description

The present invention relates to a process for the production and preparation of a synthesis gas mixture for the production of ammonia, in which a hydrocarbon-containing starting gas mixture is converted in an autothermal reformer (ATR) by means of steam and oxygen in a Rohsynthesegasgemisch, which optionally supplied after further treatment at least one ammonia synthesis reactor becomes.

In the case of existing ammonia plants, there are bottlenecks in the area of various plant components which prevent a desired increase in capacity. These are in particular the primary reformer, the secondary reformer, the process air compressor, the CO ₂ scrubbing, the synthesis gas compressor and the ammonia synthesis reactor. The circumvention of these bottlenecks requires expensive measures. There are different concepts from different providers for the economic transformation and renewal of existing plants (so-called "revamp").

From the DE 100 55 818 A1 a method for the catalytic production of ammonia from a nitrogen-hydrogen mixture is known in which one passes natural gas together with an oxygen-rich gas in an autothermal reformer, where at temperatures in the range of 900 ° C to 1200 ° C, a pressure of 40 to 100 bar and in the presence of a cleavage catalyst produces a crude synthesis gas, wherein this crude synthesis gas is withdrawn from the autothermal reformer, cooled, passes through a catalytic conversion for converting CO into H ₂ and a converted synthesis gas having an H ₂ content of subtracting at least 55% by volume and a CO content of at most 8% by volume, subjecting the converted synthesis gas to a multistage gas purification to remove CO ₂ , CO and CH ₄ and produce an N ₂ -H ₂ mixture, which is fed to ammonia synthesis for the catalytic production of ammonia. In this known method, only an autothermal reformer is provided for reforming and the ammonia synthesis takes place at only one pressure level. The liquid nitrogen is also used after the air separation plant before the synthesis gas compressor for nitrogen scrubbing, with which all inert (argon and methane) and all O ₂ -containing components (CO, CO ₂ , H ₂ O) are washed out and with the necessary ratio H ₂ : N _{2 is set} equal to 3: 1. The fresh make-up gas prior to synthesis thus contains only N ₂ and H ₂ .

In the EP 1339641 B1 a method for the synthesis of ammonia at two pressure levels is described. Here, the production of ammonia from fresh synthesis gas, which contains in addition to the reactants hydrogen and nitrogen inert constituents, successively in different synthesis systems, wherein produced in all synthesis systems in each case from a portion of the synthesis gas ammonia and a part thereof is discharged and each subsequent synthesis system a higher Pressure than the previous synthesis system.

In the WO 2016/198487 A1 also a Mehrdruckverfahren for the production of ammonia is described in which a starting gas mixture comprising hydrogen, nitrogen, water, methane, optionally argon, carbon monoxide and carbon dioxide is prepared by reforming hydrocarbons, wherein the reforming takes place in an autothermal reformer, which with pure oxygen or operated with oxygen enriched air or with air.

The object of the present invention is to provide a process for the production and preparation of a synthesis gas mixture for the production of ammonia having the features of the aforementioned type, which allows an increase in capacity of an ammonia plant bypassing or significantly weakening the abovementioned bottlenecks ,

Another concern of the present invention is to efficiently integrate an air separation plant into the revamping operations of an existing ammonia plant.

The solution of the aforementioned object provides a process for the production and preparation of a synthesis gas mixture for the production of ammonia of the type mentioned above with the features of claim 1.

According to the invention, it is provided that only a partial stream of the starting gas mixture is fed to the autothermal reformer while a further partial stream of the starting gas mixture is fed to a primary reformer and preferably subsequently to a secondary reformer and the gas mixture produced there is also fed to an ammonia synthesis reactor, if appropriate after further, known, treatment steps. wherein the synthesis gas mixture is brought to an elevated pressure and feeds it from at least one line further nitrogen before the synthesis gas mixture enters into a one- or multi-stage ammonia synthesis

Preferably, a first partial stream fed to the primary reformer is branched off from a line containing the hydrocarbons and steam and leads the others Partial flow of this gas mixture to the autothermal reformer too.

Preferably, in the variant using a primary reformer, the gas mixture leaving the primary reformer is fed to a secondary reformer.

In this preferred variant of the method according to the invention, a primary reformer and a secondary reformer are thus provided in addition to the autothermal reformer. The secondary reformer can be operated, for example, with enriched air.

According to a preferred embodiment of the invention, the crude synthesis gas stream treated in the autothermal reformer and the crude synthesis gas stream treated in the primary reformer are combined and then a common treatment of these gas streams takes place before these are fed to an ammonia synthesis reactor. The combining preferably takes place before the CO conversion, more preferably before the cooling-down, i. immediately after leaving the ATR and from the secondary reformer.

According to a preferred development of the invention, the combined treatment of these gas streams comprises at least one step in which CO conversion and / or CO ₂ scrubbing and / or methanation occur.

If the production of ammonia is a so-called multi-pressure process, then according to a preferred development of the invention, the treated synthesis gas stream is fed to at least one synthesis gas compressor where it is compressed to an increased pressure p ₁ , which is higher than the initial pressure, then to a first synthesis unit (" Once-through or "OT" ammonia synthesis, generally comprising a gas preheating, an ammonia converter (optionally comprising a plurality of catalyst beds with a gas intercooling), a gas cooling, an ammonia converter Condensation and ammonia deposition), supplied, wherein the gas stream is compressed after the ammonia deposition in the multi-pressure process by means of a further compression stage or another synthesis gas compressor to a pressure p ₂ , which is higher than the pressure p ₁ and this gas stream is then a second synthesis unit ("cycle" ammonia synthesis, also usually comprising a gas preheating, an ammonia converter (this comprising optionally a plurality of catalyst beds with a gas intermediate cooling), a gas cooling, a NH ₃ condensation and an ammonia deposition) supplied.

If, however, it is a variant of the ammonia synthesis with only one pressure level, then, according to a preferred embodiment of the invention, the treated synthesis gas stream at least one synthesis gas compressor are fed there compressed to an elevated pressure and then fed to one or more ammonia synthesis reactors.

According to a preferred embodiment of the invention, the synthesis gas mixture brought to an elevated pressure before it is fed to the cyclic ammonia synthesis and / or before it is supplied in the multi-pressure variant of an OT ammonia synthesis, in each case via a line further nitrogen.

It is particularly advantageous according to a development of the invention, when the supplied additional nitrogen produced in an air separation plant and then liquefied and pumped to the pressure p ₁ or p ₂ .

The nitrogen flowing through the secondary reformer is added, for example, between a second and a third synthesis gas compressor stage of the OT ammonia synthesis, wherein it is possible to operate at a pressure p _{1 of} the order of about 100 bar. By contrast, the nitrogen from the air separation plant is preferably pumped directly to the pressure p _{2 of} the circulatory ammonia synthesis of about 200 bar and is thus guided past the synthesis gas compressor.

However, part of the nitrogen from the air separation plant can be added to the OT ammonia synthesis to increase the ammonia yield. Preferably, different from the prior art according to DE 100 55 818 A1 Methane is not removed during gas purification, but it even creates additional methane in the methanation unit. The fresh gas before the ammonia synthesis thus contains, besides nitrogen and hydrogen, also the argon and methane gases, which are inert in relation to the ammonia synthesis, and possibly helium.

An existing air separation plant is preferably modernized so far that the products O ₂ and N _{2 are} almost pure and in liquid form, the argon is preferably separated.

According to the invention, an autothermal reformer is provided in parallel to the existing primary reformer and optionally secondary reformer, which can preferably be operated with pure oxygen from the air separation plant. The liquid oxygen is pumped to the working pressure of the autothermal reformer, for example, about 40 bar and then evaporated, the cold of the liquid oxygen is used.

The starting gas mixture, for example natural gas, is usually mixed with steam before it is introduced into the autothermal reformer or primary reformer. Since both an autothermal reformer and a primary reformer are used in the process of the present invention, the natural gas-steam mixture for the autothermal reformer may advantageously be diverted from the main stream directed into the primary reformer only before the primary reformer. In this way, one obtains two piping systems, each with at least one reformer, in which the reforming process takes place in parallel and you can use the previously generated natural gas-steam mixture in both parallel piping systems. It is advantageous to bring both Rohsynthesegasstrom after reforming in the autothermal reformer or in the primary reformer and secondary reformer together again and then process together in further process steps. This treatment can comprise, for example, CO conversion and / or CO ₂ scrubbing and / or methanation.

The liquid nitrogen from the air separation plant is preferably pumped to the final synthesis pressure of, for example, about 200 bar and mixed with the fresh gas only after the synthesis gas compressor. The cold of the supercritical nitrogen can be used.

Part of the ammonia can be formed by the OT ammonia synthesis between the compression stages of a syngas compressor (typically between the second and third stages). Optionally, a portion of the nitrogen from the air separation plant after the second compression stage of the synthesis gas compressor is added to the make-up gas to optimize the gas composition prior to OT ammonia synthesis.

Part of the oxygen is added to the secondary reformer to reduce the residual methane content so that the methane residue after the secondary reformer and after the autothermal reformer is approximately equal. This is advantageous for the economy of the process, since a lower methane residue leads to higher ammonia production.

In the method according to the invention, the distribution of the gas is new compared to the aforementioned known solutions. One advantage is, among other things, the massive relief of all process units between the secondary reformer and the main synthesis, including the process air compressor and the synthesis gas compressor. Compared to a variant with the reforming in only one autothermal reformer, an advantage of the combination according to the invention with the primary reformer is that the heat in the flue gas channel of the primary reformer can be used. Thus, the preheating of the inlet streams for the autothermal reformer in the flue gas channel of the primary reformer is possible.

According to a preferred embodiment of the invention, it is such that the supplied additional nitrogen from the air separation plant brought by at least one pump to the intended ammonia synthesis pressure and then via a line immediately before the cyclic ammonia synthesis or partially before the OT Ammonia synthesis is supplied.

A preferred embodiment of the invention provides that both the autothermal reformer and the secondary reformer oxygen is supplied, which was obtained in an air separation plant.

A preferred embodiment of the invention provides that the secondary reformer process air is supplied, which was preferably previously brought by means of a compressor to an elevated pressure and / or by means of a heat exchanger, preferably in the flue gas duct of the primary reformer, was preheated.

The process air can be additionally mixed with oxygen from outside, which was obtained in an air separation plant, and this oxygen-enriched air can be supplied to the secondary reformer.

The present invention furthermore relates to a process for the production of ammonia, in which the preparation of the ammonia is carried out using a synthesis gas mixture produced and prepared in the manner described above.

According to a preferred embodiment of the invention, a synthesis gas mixture is first generated in this process for the production of ammonia, which contains the gases hydrogen and nitrogen in a ratio H ₂ : N ₂ greater than 3 and this superstoichiometric synthesis gas mixture is then prior to introduction into the ammonia synthesis reactor added more nitrogen. This additional nitrogen was preferably produced in an air separation plant.

In the process according to the invention, the ammonia synthesis can be carried out either at only one pressure level or alternatively it can be a multi-pressure process.

The present invention further relates to a plant for the production and processing of a synthesis gas mixture for the Production of ammonia, in which a hydrocarbon-containing starting gas mixture is converted in an autothermal reformer by means of steam and oxygen / air in a Rohsynthesegasgemisch which is supplied after further treatment at least one Ammoniaksynthesereaktor, according to the invention this plant in addition to at least one autothermal reformer at least one primary reformer and preferably further comprises at least one downstream of the primary reformer in the flow path secondary reformer.

According to a further preferred development of the system according to the invention, the autothermal reformer and the secondary reformer are arranged in mutually parallel piping systems, wherein the respective output lines of autothermal reformer and secondary reformer lead into a common conduit system for synthesis gas, preferably before the CO conversion.

According to a further preferred development of the system according to the invention, this comprises at least one CO conversion and / or at least one CO ₂ scrubbing and / or at least one methanation device, which are arranged in the common synthesis gas line system downstream of autothermal reformer and secondary reformer.

The present invention further relates to a plant for the production of ammonia comprising a plant for the production and processing of a synthesis gas mixture of the type described above, this plant further comprises according to the invention at least one of the autothermal reformer and the primary reformer and optionally the secondary reformer in the flow downstream ammonia synthesis reactor. In particular, in a multi-pressure process, these may also be two or more ammonia synthesis reactors, which operate at different pressures.

• 1 ein schematisch vereinfachtes Fließbild einer ersten beispielhaften erfindungsgemäßen Anlage;
• 2 ein schematisch vereinfachtes Fließbild einer zweiten beispielhaften erfindungsgemäßen Anlage gemäß einer alternativen Variante der vorliegenden Erfindung.

Hereinafter, the present invention will be explained in more detail with reference to two embodiments with reference to the accompanying drawings. Showing:

• 1 a schematically simplified flow diagram of a first exemplary system according to the invention;
• 2 a schematically simplified flow diagram of a second exemplary system according to the invention according to an alternative variant of the present invention.

The following is with reference to 1 a first possible embodiment of the present invention explained in more detail. The illustration shows a simplified flow diagram of an exemplary plant according to the invention for the production and preparation of a synthesis gas mixture and for the subsequent production of ammonia from this synthesis gas mixture. In an air separation plant 10 Argon is separated and liquid nitrogen from the air separation plant 10 is over the line 11 a pump 12 fed and brought there to a pressure of for example about 200 bar, in a heat exchanger 13 warmed up and then over the line 14 fed to the recycle gas before this cycle ammonia synthesis 15 is forwarded.

The liquid oxygen from the air separation plant 10 is over the line 16 a pump 17 fed there, brought there to a higher pressure of for example about 40 bar, then in an evaporator 18 vaporizes and part of the gaseous oxygen is then over the line 19 the process air from the line 24 mixed before the enriched air to a secondary reformer 20 is supplied.

The natural gas is via a compressor 25 and the line 26 supplied to the system, then in a heat exchanger 27 , Preferably in the flue gas channel of the primary reformer, heated to a temperature of, for example, about 380 ° C, in a corresponding device 28 desulfurizes, then flows over the pipe 29 where an admixture of steam takes place, then through another heat exchanger 30 in the flue gas channel of the primary reformer, where the gas is heated, for example up to about 480 ° C to 600 ° C and then leaves this heat exchanger 30 over the line 31 where then a division of the natural gas / steam mixture into two partial flows, of which a partial flow through the line 32 the primary reformer 33 is supplied. In the primary reformer 33 the reaction of the hydrocarbons with the water vapor to a synthesis gas mixture containing carbon monoxide and hydrogen as the main components.

In steam reforming, methane usually reacts with water vapor in the primary reformer according to the following reaction equations (1) and (3): CH ₄ + H ₂ O → CO + 3 H ₂ (1)

As in the primary reformer 33 no complete conversion of the methane is carried out to increase the yield of hydrogen that is the primary reformer 33 leaving Rohsynthesegasgemisch over the line 34 the secondary reformer described above 20 fed in by the supply of air or oxygen methane to carbon monoxide and hydrogen according to the Reaction equation (1) and (3) and partially the following reaction equation (2) is reacted. 2 CH ₄ + O ₂ → 2 CO + 4 H ₂ (2)

That's the secondary reformer 20 leaving synthesis gas mixture is then cooled, whereby steam is generated, and is passed over the line 35 a CO conversion 36 fed. This cooling is called "waste heat recovery" (WHR), in which the gas gives off the heat to water, which then evaporates, so that the gas is cooled and heat is recovered.

The so-called CO conversion, also referred to as the water gas shift reaction, is used to reduce the carbon monoxide content in the syngas and generate additional hydrogen. It is an exothermic equilibrium reaction which follows the reaction equation (3) given below: CO + H ₂ O⇔CO ₂ + H ₂ (3)

Following the CO conversion 36 a CO ₂ scrubbing 37 is provided to remove the CO ₂ from the synthesis gas mixture.

Following the CO ₂ scrubbing, the synthesis gas flows through a device 38 for methanation, in which carbon monoxide or carbon dioxide react at elevated temperatures according to the reaction equations (4) and (5) reproduced below with hydrogen to give methane and water: CO + 3H ₂ → CH ₄ + H ₂ O (4) CO ₂ + 4H ₂ → CH ₄ + 2H ₂ O (5)

After methanation, the educt gases hydrogen and nitrogen are present in the generated synthesis gas mixture in a superstoichiometric ratio of more than 3: 1, that is, it contains more hydrogen in the gas mixture relative to nitrogen than is needed for the ammonia synthesis reaction. About the line 39 then passes the synthesis gas mixture in the synthesis gas compressor, this example, with two successive compression stages 40 and 41 can work and takes place in two stages, an increase in pressure, for example, 100 bar. As long as the water content in the fresh gas is too high (water deactivates the catalyst in the ammonia converter), the water is separated after each pressure increase, as exemplified by a device 42 will be shown. This can be done both by the condensation and by other methods known in the art. Thereafter, the fresh gas enters the OT (once through) ammonia synthesis 15, consisting of the gas preheating, an ammonia converter (possibly several catalyst beds with a gas intercooling), a gas cooling, an ammonia condensation and ammonia deposition). After the ammonia deposition, the remaining gas mixture in the present embodiment according to 1 illustrated two-pressure process in another compressor stage 43 compressed to a higher pressure of, for example, about 200 bar and then over the line 44 a second ammonia synthesis, the circulation ammonia synthesis 45 also consisting of the gas preheating, ammonia converter (several catalyst beds with a gas intercooling), gas cooling, ammonia condensation and ammonia deposition. In this cyclic ammonia synthesis, a further synthesis of ammonia takes place at a higher pressure level. From the two ammonia syntheses 15 and 45 The ammonia is as a product over the lines 46 respectively. 47 dissipated.

To the ratio of hydrogen to nitrogen in the direction 3 : 1 to change -this over the wire 39 supplied synthesis gas mixture indeed contains hydrogen in excess, - can the fresh gas before the first ammonia synthesis 15 , the OT ammonia synthesis, over from the line 14 branching branch line 57 additional nitrogen are supplied. The remaining nitrogen from the pipe 14 opens before the second ammonia synthesis, the circulation ammonia synthesis, in the line 44 , From the circulatory ammonia synthesis 45 is the ammonia as a product over the line 47 dissipated. Thus, the inert for the ammonia synthesis methane and argon and possibly helium in the recycle gas does not accumulate, a part of the gas - the so-called purge gas - after the synthesis 45 and before the mixing of the fresh gas via the line 53 dissipated. To compensate for the pressure losses in the synthesis cycle, the gas mixture over the line 54 another compressor or a further compressor stage 55 supplied in this to an elevated pressure required for the reaction and then via the return lines 56 . 44 and after admixing the fresh gas and the nitrogen from the line 14 , the circuit ammonia synthesis 45 supplied so that you can lead unreacted starting materials in the circulation and can bring in the ammonia synthesis reactor again to react.

It has already been stated above that only one branched off first partial stream of the natural gas / vapor mixture via the branch line 32 into the primary reformer. The second partial flow is after the branch over the line 48 an autothermal reformer 49 fed, which oxygen over one from the line 19 branched partial flow 19 a is supplied. The autothermal reforming is a combination of Steam reforming and partial oxidation to optimize efficiency. In this case, a hydrocarbon such as natural gas can be reformed. By combining steam reforming with partial oxidation, the advantage of oxidation, which provides thermal energy, adds to the advantage of steam reforming, which results in higher hydrogen yield. The air and water supply must be precisely metered here. That's the autothermal reformer 49 over the line 50 leaving raw synthesis gas mixture then contains approximately the same methane residue as that from the secondary reformer 20 over the line 35 emerging synthesis gas mixture. The two gas streams are best left after the cooling section before the CO conversion at the branch 51 Unite and the combined synthesis gas stream can subsequently be converted to CO 36 be initiated. After unification, therefore, the combined synthesis gas stream from the lines 50 and 35 jointly further treated and finally the ammonia synthesis 15 and 45 be supplied.

The peculiarity of the method according to the invention is thus that the process gas stream, that is, the natural gas / steam mixture is divided into two partial streams, one of which is a partial stream via the branch line 32 to reform a primary reformer 33 is fed while the other partial flow via the second branch line 48 in the autothermal reformer 49 is reformed, wherein the two partial streams then after the respective reforming at the branch 51 reunited and then treated together in the further process.

Another advantage of the method according to the invention is that the liquid nitrogen from the air separation plant 10 pumped to the final synthesis pressure of, for example, about 200 bar (with significantly less energy expenditure compared to the compression of gaseous nitrogen to the same pressure) and then over the line 14 bypassing the synthesis gas compressor 40 is mixed with fresh gas, which over the line 44 for circulatory ammonia synthesis 45 flows, so that the synthesis gas compressor is relieved. The cold of the supercritical nitrogen is used beforehand.

The following is with reference to 2 a second possible embodiment of the present invention explained in more detail. The illustration shows a simplified flow diagram according to a second alternative variant of an exemplary plant according to the invention for the production of ammonia. In this variant, the synthesis of the ammonia takes place at only one pressure level.

Large areas of the plant scheme agree with the one previously described by 1 described embodiment match.

At the in 2 illustrated variant of the system are the reference numerals 10 to 50 designated equipment parts, previously with reference to 1 have already been explained, present in the same form, so that their function is not described here again, but to the above comments 1 Reference is made.

As long as the water content in the fresh gas is too high (water deactivates the catalyst in the ammonia converter), the water is separated after each pressure increase, as exemplified by a device 42 will be shown. This can be done both by the condensation and by other methods known in the art. In the last compressor stage 43 the fresh gas is compressed to the synthesis pressure of, for example, about 200 bar and then over the line 44 the circulatory ammonia synthesis 45 fed, in which the ammonia synthesis takes place. In order to produce the necessary for the reaction stoichiometric ratio of hydrogen to nitrogen = 3: 1, - because that over the line 52 supplied synthesis gas mixture indeed contains hydrogen in excess, - is the gas mixture before the cyclic ammonia synthesis 45 over the line 14 fed additional nitrogen. To do this, the nitrogen pipe opens 14 into the pipe 44 that carries the synthesis gas mixture. From the circulatory ammonia synthesis 45 is the ammonia as a product over the line 47 dissipated. Thus, the inert for the ammonia synthesis methane and argon and possibly helium in the recycle gas does not accumulate, a part of the gas - the so-called purge gas - after the synthesis 45 and before the mixing of the fresh gas via the line 53 dissipated. To compensate for the pressure losses in the synthesis cycle, the gas mixture over the line 54 another compressor or a further compressor stage 55 supplied in this to an elevated pressure required for the reaction and then via the return lines 56 . 44 and after admixing the fresh gas and the nitrogen from the line 14 , the circuit ammonia synthesis 45 supplied so that you can lead unreacted starting materials in the circulation and can bring in the ammonia synthesis reactor again to react. Above it has already been stated that only a branched first partial flow of the natural gas / steam mixture via the branch line 32 into the primary reformer. The second partial flow is after the branch over the line 48 an autothermal reformer 49 fed, which oxygen over one from the line 19 branched partial stream is supplied. That's the autothermal reformer 49 over the line 50 leaving raw synthesis gas mixture then contains about the same Methane residue like that from the secondary reformer 20 over the line 35 emerging synthesis gas mixture. The two gas streams are best left after the cooling section before the CO conversion at the branch 51 combine and the combined synthesis gas stream can subsequently be converted to CO 36 be initiated. After unification, therefore, the combined synthesis gas stream from the lines 50 and 35 jointly further treated and finally the cyclic ammonia synthesis 45 be supplied.

The peculiarity of the method according to the invention is thus that the process gas stream, that is, the natural gas / steam mixture is divided into two partial streams, one of which is a partial stream via the branch line 32 to reform a primary reformer 33 and then fed to a secondary reformer while the other substream is via the second branch line 48 in the autothermal reformer 49 is reformed, wherein the two partial streams then after the respective reforming at the branch 51 reunited and then treated together in the further process.

Another advantage of the method according to the invention is that the liquid nitrogen from the air separation plant 10 pumped to the final synthesis pressure of, for example, about 200 bar (with significantly less energy expenditure compared to the compression of gaseous nitrogen to the same pressure) and then over the line 14 bypassing the synthesis gas compressor 40 is mixed with fresh gas, which over the line 44 for circulatory ammonia synthesis 45 flows. The cold of the supercritical nitrogen is used beforehand.

LIST OF REFERENCE NUMBERS

10

Air separation plant

11

Nitrogen pipe (liquid)

12

Nitrogen-pump

13

Nitrogen preheating

14

Nitrogen line (gaseous)

15

"Once Through" or OT ammonia synthesis, consisting of a gas preheating, ammonia converter (possibly several catalyst beds with a gas intercooling), gas cooling, ammonia condensation and ammonia deposition

16

Oxygen line (liquid)

17

Oxygen pump

18

Oxygen evaporator

19

Oxygen line (gaseous)

19a

Oxygen partial flow (gaseous)

20

secondary reformer

21

Process Air Compressor

22

Line for process air

23

Preheating process air

24

Line for process air

25

Compressor for natural gas

26

Pipe for natural gas

27

Preheating natural gas before desulphurisation

28

Device for desulfurization

29

Pipe for natural gas

30

Preheating natural gas / steam mixture

31

Pipe for natural gas / steam

32

Branch line for partial flow

33

primary reformer

34

Direction for partially reformed synthesis gas after the primary reformer

35

Line for raw synthesis gas after the cooling section after the secondary reformer

36

CO conversion

37

CO ₂ laundry

38

Device for methanation

39

Line for fresh gas

40

first compression stage of the synthesis gas compressor

41

second compression stage of the synthesis gas compressor

42

Device for separating water

43

additional compressor stage (s)

44

management

45

Circulation ammonia synthesis consisting of gas preheating, ammonia converter (multiple catalyst beds with gas intercooling), gas cooling, ammonia condensation and separation

46

Line for ammonia (liquid)

47

Line for ammonia (liquid)

48

Line for second partial flow

49

autothermal reformer

50

Line for raw synthesis gas

51

Combine the crude synthesis gas after the secondary reformer and the autothermal reformer

53

Pipe for purge gas

54

Return line

55

Circulation compressor (stage)

56

Return line

57

Branch line for nitrogen

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

• DE 10055818 A1 [0003, 0020]
• EP 1339641 B1 [0004]
• WO 2016/198487 A1 [0005]

Claims (21)

A process for the production and purification of a synthesis gas mixture for the production of ammonia, in which a hydrocarbon and steam containing feed gas mixture is converted into an autothermal reformer (49) by means of oxygen in a Rohsynthesegasgemisch which, in at least one ammonia synthesis (15, 45) is fed by in that only one substream (48) of the starting gas mixture is fed to the autothermal reformer (49), while a further substream (32) of the starting gas mixture is fed to a primary reformer (33) and the gas mixture produced in the primary reformer is likewise fed to an ammonia synthesis (15, 45) in which the synthesis gas mixture (44) is brought to an elevated pressure and fed thereto from at least one line (14, 57) further nitrogen, before the synthesis gas mixture enters into a one- or multi-stage ammonia synthesis. Method according to Claim 1 , characterized in that the gas mixture produced in the primary reformer (33) is then fed to a secondary reformer (20). Method according to Claim 1 or 2 , characterized in that a first, the primary reformer (33) and optionally then the secondary reformer (20) supplied partial stream (32) from a hydrocarbon mixture and steam-containing gas mixture leading line (31) branches off and the remaining part stream (48) of this gas mixture the autothermal reformer (49) feeds. Method according to one of Claims 1 to 3 , characterized in that the ammonia synthesis (15, 45) comprises a gas preheating before the reaction in an ammonia converter, and a subsequent gas cooling, ammonia condensation and ammonia deposition. Method according to Claim 4 , characterized in that the ammonia synthesis takes place in an ammonia converter with a plurality of catalyst beds, wherein a gas intermediate cooling is provided. Method according to one of Claims 2 to 5 , characterized in that in the autothermal reformer (49) treated Rohsynthesegasstrom (50) and in the secondary reformer (20) treated Rohsynthesegasstrom (35) combined and then carried out a common treatment of these gas streams, before this ammonia synthesis (15, 45 ). Method according to Claim 6 , characterized in that the combined treatment of these gas streams comprises at least one step in which a CO conversion (36) and / or a CO ₂ scrubbing (37) and / or a methanation (38) takes place. Method according to one of Claims 6 or 7 , characterized in that the processed synthesis gas stream is fed to at least one synthesis gas compressor (40, 41) where it is compressed to an elevated pressure p ₁ , which is higher than the initial pressure, then fed to a first ammonia synthesis (15), preferably comprising one Gas preheating, an ammonia converter, optionally with a plurality of catalyst beds and with a gas intermediate cooling, a gas cooling, ammonia condensation and ammonia deposition, then the ammonia synthesis (15) leaving the product gas mixture by means of at least one another compression stage (43) is compressed to a pressure p ₂ , which is higher than the pressure p ₁ and this gas stream (44) after the admixture of the nitrogen from the conduit (14) then a second ammonia synthesis (45), also preferably comprising a Gas preheating, an ammonia converter, optionally with multiple catalyst beds and with a gas-Zwi shear cooling, a gas cooling, an ammonia condensation and an ammonia deposition, is supplied. Method according to one of Claims 1 to 8th , characterized in that the supplied additional nitrogen in an air separation plant (10) was generated. Method according to Claim 9 , characterized in that the supplied further nitrogen from the air separation plant (10) by means of at least one compressor or a pump (12) brought to the intended ammonia synthesis pressure and then via a line (14) or 57 the gas mixture immediately before the ammonia synthesis ( 45) or in each case before the ammonia synthesis (15, 45) is supplied. Method according to one of Claims 2 to 10 , comprising, characterized in that both the autothermal reformer (49) and the secondary reformer (20) oxygen is supplied, which was obtained in an air separation plant (10). Method according to one of Claims 2 to 11 , characterized in that the secondary reformer (20) process air is supplied, which was previously brought by means of a compressor (21) to an elevated pressure which is higher than the outlet pressure and which has been preheated by means of at least one heat exchanger (23). Process for the preparation of ammonia, characterized in that the preparation of the Ammonia using a method according to any one of Claims 1 to 12 produced and prepared synthesis gas mixture takes place. Process for the preparation of ammonia Claim 13 , characterized in that in this a synthesis gas mixture is generated, which contains the gases hydrogen and nitrogen in a ratio H ₂ : N ₂ greater than 3 and this superstoichiometric synthesis gas mixture either after at least one compression stage of a synthesis gas compressor (40, 41), or if it has almost synthesis pressure, before being introduced into the ammonia synthesis, more nitrogen is added. Process for the preparation of ammonia according to one of Claims 13 or 14 , characterized in that in this method, the ammonia synthesis is carried out at only one pressure level. Method according to one of Claims 13 or 14 , characterized in that the ammonia synthesis is carried out at two or more pressure levels. Plant for the production and preparation of a synthesis gas mixture for the production of ammonia, wherein a hydrocarbon and steam-containing starting gas mixture is converted in an autothermal reformer (49) by means of oxygen in a Rohsynthesegasgemisch which after further processing at least one ammonia synthesis (15, 45), respectively , preferably for carrying out a method according to one of Claims 1 to 12 , characterized in that the system comprises at least one primary reformer (33) in addition to at least one autothermal reformer (49). Plant after Claim 17 , characterized in that it further comprises at least one secondary reformer (20) connected downstream of the primary reformer (33) in the flow path . Plant after Claim 18 , characterized in that the autothermal reformer (49) and the secondary reformer (20) are arranged in mutually parallel piping systems, wherein the respective output lines of autothermal reformer and secondary reformer lead into a common system of synthesis gas. Plant according to one of the Claims 18 or 19 characterized in that it comprises at least one CO conversion (36) and / or at least one CO ₂ scrubbing (37) and / or at least one methanation device (38) operating in the common synthesis gas manifold downstream of autothermal reformer (49) and secondary reformer (20) are arranged. Plant for the production of ammonia comprising a plant for the production and treatment of a synthesis gas mixture according to one of Claims 18 to 20 characterized in that it further comprises at least one ammonia synthesis (15, 45) downstream of the autothermal reformer (49) and the primary reformer (20) in the flow path, each preferably comprising a gas preheating, at least one ammonia Converter with one or more catalyst beds, with optional gas intercooling, gas cooling, ammonia condensation and ammonia deposition.

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