AMMONIA PLANT HAVING A START-UP FURNACE AND METHOD FOR PRODUCING AMMONIA

Abstract

An ammonia plant having a first and second reactor and a start-up oven having at least one first heat exchanger. The first reactor operates under a higher internal pressure than the second reactor. The start-up oven is connected via a piping system for at least one synthesis gas to the first and second reactor. Ammonia is produced by heating synthesis gas in the start-up oven and transferring the heated synthesis gas to the first reactor for initiating the chemical reaction. Synthesis gas is heated with the same start-up oven and is transferred to the second reactor for initiating the chemical reaction, wherein high-pressure synthesis of ammonia occurs in the first reactor and low-pressure synthesis of ammonia occurs in the second reactor at a lower process pressure than in the first reactor.

Claims

1-12. (canceled)

13. An ammonia plant, comprising: a first reactor configured to generate a first ammonia synthesis; a second reactor configured to generate a second ammonia synthesis; a start-up oven having at least one first heat exchanger; and a piping system interconnecting the start-up oven to the first and second reactor; wherein said start-up oven is connected to the first reactor via first pipes of the piping system for delivering reactants for a first ammonia synthesis and connected to the second reactor via second pipes of the piping system for delivering reactants for a second ammonia synthesis; wherein the start-up oven is arranged in the flow path of the piping system such that the start-up oven is selectably connectable only to the first pipes or only to the second pipes.

14. The ammonia plant of claim 13, further comprising at least one compressor having at least two compressor stages, wherein the compressor is arranged in the flow path of the piping system and configured to produce an elevation of the process pressure in the second pipes of the second reactor while maintaining the process pressure in the first pipes of the first reactor.

15. The ammonia plant of claim 13, further comprising shutoff valves arranged in the piping system, the shutoff valves configured to switch the delivery of reactants to one or the other of the first and second reactor.

16. The ammonia plant of claim 13 wherein the start-up oven further comprises a second heat exchanger, wherein first heat exchanger is connected to the first reactor via the first pipes and the second heat exchanger is connected to the second reactor via the second pipes.

17. The ammonia plant of claim 13 wherein the first heat exchanger is connected to the first reactor via the first pipes, and wherein a third pipe branches off from the first pipes, wherein the first heat exchanger is connected to the second reactor via the third pipe.

18. The ammonia plant of claim 17 wherein at least one first shutoff valve is operatively associated with the first pipes and configured to decouple the first reactor from the third pipe and the first heat exchanger, wherein at least one second shutoff valve is operatively associated with the third pipe and configured to decouple the first pipe from the second reactor.

19. A method of producing ammonia, comprising: heating, with a start-up oven, a first synthesis gas for a first ammonia synthesis in a first reactor; transferring the heated first synthesis gas to the first reactor for initiating a chemical reaction; heating, with the start-up oven, a second synthesis gas for a second ammonia synthesis in a second reactor; and transferring the heated second synthesis gas to the second reactor for initiating a chemical reaction, wherein a high-pressure synthesis of ammonia is carried out in the first reactor and a low-pressure synthesis of ammonia is carried out in the second reactor at a process pressure which is lower than the process pressure in the first reactor.

20. The method of claim 19 wherein the start-up oven comprises a first heat exchanger and a second heat exchanger which are independent of one another, wherein the first synthesis gas has a higher partial pressure in the first heat exchanger and/or upon introduction into the first reactor than the second synthesis gas in the second heat exchanger and/or upon introduction into the second reactor.

21. The method of claim 19 wherein the transfer of the first synthesis gas to the first reactor and the transfer of the second synthesis gas to the second reactor are carried out successively, wherein a transfer of the first synthesis gas through the first heat exchanger and into the first reactor is followed by a transfer of the second synthesis gas through the first heat exchanger and into the second reactor.

22. The method of claim 19 wherein the transfer of the first and second synthesis gas is carried out simultaneously, wherein a transfer of the first synthesis gas through the first heat exchanger and into the first reactor is carried out and a proportion of the first synthesis gas is diverted into the second reactor after heating by the first heat exchanger.

23. The method of claim 20 wherein the transfer is carried out simultaneously or successively, wherein the first synthesis gas is passed through the first heat exchanger and into the first reactor and the second synthesis gas is passed through the second heat exchanger and into the second reactor, wherein the first and second heat exchanger are arranged in the start-up oven.

24. The method of claim 19 wherein the start-up oven comprises burners operated with the same gas also used as reformer gas for producing hydrogen for the ammonia synthesis and/or the start-up oven heats the first heat exchanger under atmospheric pressure.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] In the figures:

[0042] FIG. 1 shows a schematic view of a first embodiment of the industrial plant in the context of the invention;

[0043] FIG. 2 shows a schematic view of a second embodiment of the industrial plant in the context of the invention;

[0044] FIG. 3 shows a schematic view of a third embodiment of the industrial plant in the context of the invention.

EMBODIMENTS OF THE INVENTION

[0045] Where reference is made in the description which follows to “reactants” this is, in the synthesis of ammonia, in each case to be understood as meaning synthesis gases containing the gases nitrogen and hydrogen as reactants. FIG. 1 shows a first embodiment of the industrial plant 1 comprising a first reactor 21 and a second reactor 23 and also a start-up oven 3 having at least one first heat exchanger 5, wherein the first reactor 21 is configured and adapted for a higher internal pressure than the second reactor 23, wherein said start-up oven 3 is connected via a piping system 9, 11, 13, 15 for at least one reactant both to the first and to the second reactor. In this embodiment the first heat exchanger 5 is connected via the first pipe 9, 11 to the first reactor 21, wherein a third pipe 15 branches off from the first pipe 9, wherein the first heat exchanger 5 is connected via the third pipe 15 to the second reactor 23. Here, the third pipe 15 branches off after the first pipe 9 has passed through the start-up oven 3. There is a first source 25 comprising a feed conduit 11 for reactants for the first reactor 21 and a second source 27 comprising a further feed conduit 13 for reactants for the first reactor 23. Said sources 25, 27 are thus not identical. A fourth pipe in the form of a feed conduit 13 which opens into the first pipe 11 is provided and the reactants may be transferred through the fourth pipe 13 via a section of the first pipe through the heat exchanger 5 into the third pipe 15. Shutoff valves 9′, 11′ in the first pipe are provided so as to separate the first reactor 21 and the first source 25 of the reactants from the third and fourth pipe 13, 15. The third and fourth pipe 13, 15 likewise have valves to allow separation of the second reactor 23 and a second source 27 from a closed circuit comprising the first source 25, the first heat exchanger 5 and the first reactor 21. Furthermore, orifice plates 9″, 11″, 13″, 15″ are in each case provided in order to be able to regulate the flow. A burner 17 is also depicted.

[0046] When using the industrial plant as shown in FIG. 1 the transfer of the at least one first reactant and/or second reactant into the first and second reactor 21, 23 is preferably carried out successively, wherein a transfer of the first reactants from the first source 25 through the first heat exchanger 5 and into the first reactor 21 is followed by a transfer of the second reactant from the second source 27 through the first heat exchanger 5 and into the second reactor 23.

[0047] FIG. 2 shows a second embodiment of the industrial plant 101 comprising a first reactor 121 and a second reactor 123 and also a start-up oven 103 having at least one first heat exchanger 105 and a second heat exchanger 107, wherein the first reactor 121 is configured and adapted for a higher internal pressure than the second reactor 123, wherein said start-up oven 103 is connected via a piping system 109, 111, 113, 115 for at least one reactant both to the first and to the second reactor 121, 123. The piping system has a first pipe 113, 115 and a second pipe 111, 109, wherein the first heat exchanger 105 is connected via the first pipe 109, 111 to the first reactor 121 and the second heat exchanger 107 is connected via the second pipe 113, 115 to the second reactor 123. It is provided that the first pipe 109, 111 and the second pipe 113, 115 are spaced apart from one another and separate from one another and not connected to one another via further pipes. It has surprisingly been found that both heat exchangers 105, 107 of the one start-up oven may be heated together, in particular utilizing the same burners. Separate first and second sources 125, 127 are also provided for and may be decoupled from the corresponding reactors 121, 123 via valves 113′, 115′, 109′, 111′. A burner 117 is also depicted.

[0048] When using the industrial plant as shown in FIG. 2 the transfer is preferably carried out simultaneously, wherein the first reactant from the first source 125 is passed through the first heat exchanger 105 and into the first reactor 121 and the second reactant from the second source 127 is passed through a second heat exchanger 107 into the second reactor 123.

[0049] FIG. 3 shows a third embodiment of the industrial plant 201 comprising a first reactor 221 and a second reactor 223 and also a start-up oven 203 having at least one first heat exchanger 205, wherein the first reactor 221 is configured and adapted for a higher internal pressure than the second reactor 223, wherein said start-up oven 203 is connected via a piping system 209, 211, 215 for at least one reactant both to the first and to the second reactor 221, 223. The first heat exchanger 205 is connected via the first pipe 211, 209 to the first reactor 221, wherein a third pipe 215 branches off from the first pipe 209, wherein the first heat exchanger 205 is connected via the third pipe 215 to the second reactor 223. The third pipe 215 branches off after the first pipe 209, 211 has passed through the start-up oven 203. Simultaneous operation is possible, wherein the third pipe 215 is supplied with reactants via the first pipe 209, 211, i.e. a fourth pipe is not provided and the source 225 of the reactants for the first and second reactor 221, 223 is identical. A valve 215′ is provided to allow decoupling of the second reactor 223 from the first pipe 209, 211. Further valves 209′, 211′ make it possible to decouple the first reactor 221 and/or the first source 225. In this embodiment the orifice plate 215″ which assists in flow regulation is of particular importance. A burner 217 is also depicted.

[0050] When using the industrial plant as shown in FIG. 3 the transfer is preferably carried out successively, wherein the first reactant from the source 225 is passed through the first heat exchanger 205 into the first reactor 221 and a proportion of the first reactant is diverted into the second reactor 223 after heating by the first heat exchanger 205.

[0051] The features of the invention disclosed in the above description, the claims and the drawings may be advantageous for realizing the invention both individually and in any desired combination.