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EP-4741336-A1 - PROCESS FOR EXCHANGING A PACKED BED FROM A PRE-CRACKING REACTOR

EP4741336A1EP 4741336 A1EP4741336 A1EP 4741336A1EP-4741336-A1

Abstract

Process for exchanging a packed bed from a pre-cracking reactor (201) of an installation (200) for producing a hydrogen product from an ammonia feedstock stream, comprising the following steps: • opening (2) the bypass line valve (211) to open the bypass line (210), • closing (3) the pre-cracking reactor inlet valve (213) and the pre-cracking reactor outlet valve (214) to isolate the pre-cracking reactor (201), • unloading (4) the packed bed from the pre-cracking reactor (201), • loading (5) a new packed bed inside the pre-cracking reactor (201), • opening (6) the pre-cracking reactor inlet valve and the pre-cracking reactor outlet valve, the process being performed while: - providing (100) an ammonia feedstock stream, - in the main ammonia cracking reactor (203), performing (101) an endothermic reaction of ammonia cracking for producing said hydrogen product with said provided ammonia feedstock stream as a feed.

Inventors

  • ULBER, DIETER
  • Knoedl, Dominik
  • LUTZ, MICHAEL
  • Doomra, Arsh
  • VICARI, Lorenzo

Assignees

  • L'AIR LIQUIDE, SOCIETE ANONYME POUR L'ETUDE ET L'EXPLOITATION DES PROCEDES GEORGES CLAUDE

Dates

Publication Date
20260513
Application Date
20241112

Claims (15)

  1. Process for exchanging a packed bed from a pre-cracking reactor (201) of an installation (200) for producing a hydrogen product from an ammonia feedstock stream, the installation comprising: - a feed end (202) of the installation, - said pre-cracking reactor (201) configured to contain said packed bed, said pre-cracking reactor being arranged for receiving the ammonia feedstock stream from said feed end (202) to produce a partially converted ammonia stream, - a main ammonia cracking reactor (203), arranged for receiving the partially converted ammonia stream, - a bypass line (210) arranged for routing the ammonia feedstock stream to the main ammonia cracking reactor (203) while bypassing the pre-cracking reactor (201), said bypass line comprising a bypass line valve (211), arranged to fluidically open or close said bypass line, - a pre-cracking reactor inlet valve (213) and a pre-cracking reactor outlet valve (214), arranged to fluidically isolate the pre-cracking reactor (201) from said feed end (202) and from said main ammonia cracking reactor (203), the process for exchanging the packed bed comprising the following steps: • opening (2) the bypass line valve (211) to open the bypass line (210), • closing (3) the pre-cracking reactor inlet valve (213) and the pre-cracking reactor outlet valve (214) to isolate the pre-cracking reactor (201), • unloading (4) the packed bed from the pre-cracking reactor (201), • loading (5) a new packed bed inside the pre-cracking reactor (201), • opening (6) the pre-cracking reactor inlet valve and the pre-cracking reactor outlet valve, the process being performed while: - providing (100) an ammonia feedstock stream, - in the main ammonia cracking reactor (203), performing (101) an endothermic reaction of ammonia cracking for producing said hydrogen product with said provided ammonia feedstock stream as a feed.
  2. Process according to claim 1, wherein the steps of unloading (4) the packed bed from the pre-cracking reactor and loading (5) a new packed bed inside the pre-cracking reactor (201) are performed while routing the provided ammonia feedstock stream to the main ammonia cracking reactor (203), in particular from the feed end (202) of the installation to the main ammonia cracking reactor (203), through said bypass line (210).
  3. Process according to any one of the preceding claims, wherein the step of providing (100) an ammonia feedstock stream comprises a step of pre-heating (102) the ammonia feedstock stream, performed in a feed pre-heater (204), thereby producing a pre-heated ammonia stream, the process comprising a step (9) of reducing the temperature of the pre-heated ammonia stream performed before the step (2) of opening the bypass line valve (211) to open the bypass line (210).
  4. Process according to any one of the preceding claims, wherein the step of providing (100) an ammonia feedstock stream comprises a step of superheating the partially converted ammonia stream, performed in a feed superheater (205), thereby producing a superheated ammonia feedstock stream.
  5. Process according to any one of the preceding claims, comprising a step (7) of reducing the load of the installation, performed before the step (2) of opening the bypass line valve to open the bypass line.
  6. Process according to any one of the preceding claims, comprising a step (14) of purging the pre-cracking reactor (201) with nitrogen by routing a purging nitrogen stream through the pre-cracking reactor.
  7. Process according to any of the preceding claims, comprising a step of (22) heating up the new packed bed of the pre-cracking reactor (201).
  8. Process according to claim 7, wherein the step (22) of heating up the new packed bed of the pre-cracking reactor (201) comprises: - a step (23) of fluidically connecting the pre-cracking reactor to a start-up loop of the installation, - a step (24) of flowing a nitrogen heat-up stream through the start-up loop and the pre-cracking reactor.
  9. Process according to any one of the preceding claims, comprising a step (35) of increasing the load of the installation, this step being performed after the step (5) of loading the new packed bed to the pre-cracking reactor (201).
  10. Process according to any of claims 5 to 9 in combination with claim 4 or according to claim 4, comprising a step of routing a first part of the ammonia feedstock stream to the pre-cracking reactor (201) for performing an endothermic reaction of ammonia pre-cracking and routing a second part of the ammonia feedstock stream through the bypass line to the main ammonia cracking (203) reactor for performing an endothermic reaction of ammonia cracking and a step of controlling a flow rate of the ammonia feedstock stream through the bypass line by controlling the bypass line valve opening, such as to control the temperature at the feed superheater (205).
  11. Installation (200) for producing a hydrogen product from an ammonia feedstock stream, said installation comprising: - a feed end (202) of the installation, - a pre-cracking reactor (201) configured to contain a packed bed and arranged for receiving the ammonia feedstock stream from said feed end (202) to produce a partially converted ammonia stream, - a main ammonia cracking reactor (203) arranged for receiving the partially converted ammonia stream, - a bypass line (210), said bypass line comprising: • a bypass line valve (211), arranged to fluidically open or close said bypass line, • a bypass line duct (212) arranged for routing the ammonia feedstock stream to the main ammonia cracking reactor (203) while bypassing the pre-cracking reactor (201), - a pre-cracking reactor inlet valve (213) and a pre-cracking reactor outlet valve (214) arranged to fluidically isolate the pre-cracking reactor (201) from said feed end (202) and from said main ammonia cracking reactor (203).
  12. Installation (200) according to claim 11, wherein the bypass line duct (212) is arranged for routing the ammonia feedstock stream from the feed end (202) of the installation to the main ammonia cracking reactor (203) while bypassing the pre-cracking reactor (201).
  13. Installation according to any one of the claims 11 to 12, comprising a nitrogen stream purge line (235) arranged for routing a purging nitrogen stream through the pre-cracking reactor (201), said nitrogen stream purge line (235) comprising: - a nitrogen supply (236) duct arranged for routing the purging nitrogen stream to the pre-cracking reactor (201), - a purge discharge duct (235) arranged for routing the purging nitrogen stream from the pre-cracking reactor (201) to a fired equipment (222) as a portion of a waste gas or to an open vent, - at least one nitrogen stream purging valve (238) arranged to open or to close the nitrogen stream purge line (235).
  14. Installation according to any one of the claims 11 to 13, comprising at least one double block and bleed valve, said double block and bleed valve comprising: - two shut-off valves (245) fluidically arranged in series, each shut-off valve being configured for, in a closed position of the shut-off valve, preventing a gas stream from circulating, - a bleed valve (246) fluidically connected between said two shut off valves (245) to purge a gas contained between said shut-off valves in said closed position.
  15. Installation (200) according to claim 14, wherein the bypass line valve (211) and/or the pre-cracking reactor inlet valve (213) and/or the pre-cracking reactor outlet valve (214) is a double block and bleed valve as in claim 14.

Description

The field of the present invention is that of a process for producing hydrogen product from ammonia. The present invention also relates to a system for producing hydrogen product from ammonia. Ammonia Cracking is a new technology for large scale hydrogen production. The production of a hydrogen product by an endothermic cracking reaction of ammonia feedstock can be done in a cracking reactor at elevated temperature. Systems comprising an adiabatic pre-cracking reactor followed by a cracking reactor for producing hydrogen from ammonia are known from the prior art. Pre-cracking is an important step in the overall cracking process in order to have high heat integration and not co-produce export steam. The cracking reactor and the pre-cracking reactor can typically contain one or several packed beds, for example containing precious and non-precious metal catalysts. However, those packed beds can be damaged by poisons, excursions or by fast aging. As packed bed examples, both the Ruthenium and the high Nickel containing catalysts are sensitive to catalyst poisons. Ammonia can contain poisons, originating from oil-lubricated compressors or from ship transport. Also the small water content (0.2-0.5%) in industrial ammonia can be detrimental to certain catalysts. Upset operating conditions, like temperature excursions, in the pre-cracker or cracker can also lead to loss of catalyst performance by thermal or hydrothermal aging and agglomeration of the catalyst particles. Furthermore, the ammonia pre-cracking catalysts are newly developed products without a long-term industrial reference. Catalyst vendors cannot provide long catalyst guaranteed lifetimes of 3-4 years as requested by customers. It is then necessary to regularly exchange said catalysts creating long plant standstill and hydrogen production loss. This exchange poses particularly crucial safety issues when the process implies ammonia, as it is more dangerous and toxic than natural gas. There is currently a need for a maintenance process allowing to exchange one or several packed bed while managing the toxicity of the ammonia and while preserving safe operating conditions. There is currently a need to improve the plant yield for the production of hydrogen from ammonia at a reasonable cost. An aim of the present invention is to improve the hydrogen production in order to increase the yield of the pre-cracking and cracking stages and reduce the cost of the production method. For this purpose, the invention proposes a process for exchanging a packed bed from a pre-cracking reactor of an installation for producing a hydrogen product from an ammonia feedstock stream, the installation comprising: a feed end of the installation,said pre-cracking reactor configured to contain said packed bed, said pre-cracking reactor being arranged for receiving the ammonia feedstock stream from said feed end to produce a partially converted ammonia stream,a main ammonia cracking reactor, arranged for receiving the partially converted ammonia stream,a bypass line arranged for routing the ammonia feedstock stream to the main ammonia cracking reactor while bypassing the pre-cracking reactor, said bypass line comprising a bypass line valve, arranged to fluidically open or close said bypass line,a pre-cracking reactor inlet valve and a pre-cracking reactor outlet valve, arranged to fluidically isolate the pre-cracking reactor from said feed end and from said main ammonia cracking reactor, the process for exchanging the packed bed comprising the following steps: opening the bypass line valve to open the bypass line,closing the pre-cracking reactor inlet valve and the pre-cracking reactor outlet valve to isolate the pre-cracking reactor,unloading the packed bed from the pre-cracking reactor,loading a new packed bed inside the pre-cracking reactor,opening the pre-cracking reactor inlet valve and the pre-cracking reactor outlet valve,the process being performed while: providing an ammonia feedstock stream,in the main ammonia cracking reactor, performing an endothermic reaction of ammonia cracking for producing said hydrogen product with said provided ammonia feedstock stream as a feed. The process may comprise one or more of the following optional features alone or in combination: The process is performed while routing the provided ammonia feedstock stream to the main ammonia cracking reactor for performing said endothermic reaction of ammonia cracking. The bypass line is arranged for routing the ammonia feedstock stream from the feed end of the installation to the main ammonia cracking reactor while bypassing the pre-cracking reactor. In particular, the steps of unloading the packed bed from the pre-cracking reactor and loading a new packed bed inside the pre-cracking reactor are performed while routing the provided ammonia feedstock stream to the main ammonia cracking reactor, in particular from the feed end of the installation to the main ammonia cracking reactor, through said bypass