Device for carrying out endothermic reaction of gas feed

Abstract

The invention relates to a device for carrying out an endothermic reaction of a gas feed, said device comprising:-a preheater (11) arranged to preheat said gas feed,-at least one reaction tube (22),-a furnace (21) arranged to radiatively and / or convectively heat said at least one reaction tube (22), the invention relates to a reactor (1) for producing a gas, comprising a furnace (21) comprising at least one reaction tube (22) at least partially filled with a catalyst material (30) configured to promote an endothermic reaction, the at least one reaction tube (22) comprising:-a tube inlet for a preheated gas feed,-a main reaction tube portion (34) extending inside the furnace (21) and a pre-reaction tube portion (33) extending outside the furnace (21), the pre-reaction tube portion (33) is arranged between the tube inlet and the main reaction tube portion (34), where a portion of the catalyst material (30) extends within the pre-reaction tube portion (33).

Description

Technical Field

[0001] The present invention relates to a device for carrying out an endothermic reaction of a gaseous feed and also to the use of the device for such an endothermic reaction. Background Art

[0002] Endothermic processes for producing synthesis gas from hydrocarbon feedstocks are known. Synthesis gas can be used, in particular, to produce ammonia or hydrogen. Endothermic processes for decomposing ammonia into hydrogen and nitrogen are also known for recovering hydrogen from ammonia. The recovered hydrogen has better combustion properties than ammonia itself and is suitable for industrial use or as a transportation fuel. A typical reformer or cracker unit typically includes one or more fired catalyst-filled tubes.

[0003] It is known to have a pre-reaction step of the gas feed in the main reactor, such as a pre-reforming or pre-cracking step, followed by a main reaction step, such as a main reforming or main cracking step. The pre-reaction step allows the heat load in the main reactor to be reduced for the heat input of the endothermic process. Prior art solutions usually use a simple adiabatic pre-reactor separate from the main reactor for the pre-reaction step. The endothermic heat of the reaction is provided via the preheated gas feed.

[0004] However, these solutions require additional equipment, including a separate pre-reactor and associated piping. Consequently, they require more floor space and are more complex. Summary of the Invention

[0005] The present invention relates to a device for endothermic reaction of gas feed, comprising:

[0006] - a preheater arranged for preheating the gas feed,

[0007] - at least one reaction tube,

[0008] - a furnace arranged for radiative and / or convective heating of the at least one reaction tube,

[0009] The at least one reaction tube is at least partially filled with a catalyst material configured to promote an endothermic reaction, the at least one reaction tube comprising:

[0010] - a pipe inlet for said preheated gas feed,

[0011] a main reaction tube section extending inside the furnace and a pre-reaction tube section extending outside the furnace, the pre-reaction tube section being arranged between the tube inlet and the main reaction tube section,

[0012] A portion of the catalyst material extends within the pre-reaction tube portion.

[0013] The preheated gas feed entering the pre-reaction tube section undergoes a pre-reaction in an endothermic pre-reaction on the catalyst filling the pre-reaction tube section. This reduces the heat load from the furnace to the main reaction tube section, thereby reducing excess heat from the furnace. The present invention achieves this pre-reaction and its advantages without requiring the additional equipment of the prior art, which becomes optional.

[0014] The furnace is in particular arranged for radiative and / or convective heating of the main reaction tube section.

[0015] In one embodiment, the pre-reaction tube section is arranged to partially react the preheated gas feed in a pre-reaction to obtain partially reacted gas, and the main reaction tube section is arranged to further react the partially reacted gas in a main reaction.

[0016] In one embodiment, the length of the pre-reaction tube portion is 30% to 80% of the total reaction tube length, particularly, the length of the pre-reaction tube portion is between 4 meters and 10 meters, and the total reaction tube length is between 12 meters and 18 meters.

[0017] In one embodiment, the furnace includes a radiation and convection chamber surrounding the main reactor tube section for radiative and / or convective heat transfer to the main reactor tube section. The pre-reactor tube section extends beyond the radiation and convection chamber. In particular, the radiation and convection chamber is a continuous chamber surrounding the main reactor tube section. The radiation and convection chamber can be defined by refractory material.

[0018] In one embodiment, the furnace comprises an electric heater arranged for heating said at least one reaction tube. In particular, said electric heater is arranged within said radiation and convection chamber.

[0019] In one embodiment, the apparatus, in particular the at least one reaction tube, includes at least one heat exchanger channel, which is arranged to discharge product gas generated by the endothermic reaction from the at least one reaction tube and transfer heat from the product gas, in particular from the discharged product gas, to at least a portion of the catalyst material. In particular, the at least one heat exchanger channel is arranged within the at least one reaction tube. Preferably, the at least one heat exchanger channel extends through at least a portion of the catalyst material within the at least one reaction tube. The at least one heat exchanger channel has, for example, a straight shape, an at least partially coiled shape, or an at least partially spiral shape.

[0020] In one embodiment, the at least one heat exchanger channel is arranged to discharge product gas in countercurrent to the gas feed and product gas circulating within the catalyst material.

[0021] In one embodiment, the portion of the catalyst material extending within the pre-reacter tube portion is an upstream portion of the catalyst material.

[0022] In one embodiment, the at least one heat exchanger channel is arranged to transfer heat from the product gas, particularly from the exhausting product gas, to at least a portion of the upstream portion of the catalyst material. In this latter embodiment, the arrangement enables the hot product gas exhausted through the at least one heat exchanger channel to transfer heat to the endothermic pre-reaction of the gaseous feed in the upstream portion of the catalyst material, thereby increasing the conversion rate of the pre-reaction. In particular, the at least one heat exchanger channel extends through at least a portion of the upstream portion of the catalyst material within the at least one reaction tube.

[0023] In one embodiment, the at least one heat exchanger channel is arranged to transfer heat from the product gas, in particular from the exhaust product gas, to only a portion of the upstream portion of the catalyst material. The degree of heating of the upstream portion of the catalyst material, and therefore the degree of pre-reaction conversion, can be adjusted in this manner. In particular, the at least one heat exchanger channel extends through only a portion of the upstream portion of the catalyst material within the at least one reaction tube.

[0024] In one embodiment, the portion of the catalyst material extending within the pre-reactor tube portion is an upstream portion of the catalyst material, and the downstream portion of the catalyst material extends within the main reactor tube portion.

[0025] In one embodiment, the upstream portion of the catalyst material has a lower catalyst activation temperature than the downstream portion of the catalyst material. For example, the upstream portion comprises an active material that is different from the active catalyst material in the downstream portion and / or the upstream portion comprises a higher content of active catalyst material than the downstream portion. In particular, the upstream portion comprises an active material that has a lower catalyst activation temperature than the active catalyst material in the downstream portion.

[0026] In one embodiment, the at least one heat exchanger channel extends through the downstream portion of the catalyst material and extends through at least a portion of the upstream portion of the catalyst material. In particular, the at least one heat exchanger channel extends only through a portion of the upstream portion of the catalyst material. In one embodiment, the at least one heat exchanger channel has a first shape in the downstream portion and a second shape different from the first shape in the upstream portion. For example, the at least one heat exchanger channel may have a straight tube shape in the downstream portion and a coil or spiral shape in the upstream portion. Conversely, the at least one heat exchanger channel may have a coil or spiral shape in the downstream portion and a straight tube shape in the upstream portion.

[0027] In one embodiment, the at least one heat exchanger channel is arranged to transfer heat from the product gas, particularly from the exhaust product gas, only to the downstream portion of the catalyst material. In this embodiment, the preheating of the gas feed is sufficient to carry out the pre-reaction, and the upstream portion of the catalyst material has a temperature profile similar to that of the catalyst material of the adiabatic reactor. In particular, the at least one heat exchanger channel extends within the at least one reactor tube only through the downstream portion of the catalyst material.

[0028] In one embodiment, the apparatus comprises at least one inlet header connected to said tube inlets for supplying preheated gas feed to said at least one reaction tube.

[0029] In one embodiment, the apparatus includes at least one outlet header connected to at least one heat exchanger channel to discharge product gas generated by the endothermic reaction from the at least one heat exchanger channel.

[0030] In one embodiment, the apparatus includes a fuel and combustion oxidant system configured for combustion of fuel and oxidant gas within the furnace. Specifically, a radiant and convection chamber is configured to provide heat from the fuel and combustion oxidant system to the primary reaction portion of the at least one reaction tube via radiation and / or convection heat transfer. The fuel and combustion oxidant system typically includes at least one burner nozzle opening within the radiant and convection chamber.

[0031] In one embodiment, the apparatus comprises an equipment chamber separate from the furnace, said equipment chamber comprising at least a portion of the fuel and combustion oxidant system and / or comprising said at least one inlet header and / or said at least one outlet header. In particular, said equipment chamber is free of refractory material.

[0032] In one embodiment, the furnace is bounded by a furnace wall, in particular, by the furnace wall and the apparatus chamber, and the pre-reaction tube section is bounded by the furnace wall and the main reaction tube section. In particular, the fuel and combustion oxidant system are mounted on the furnace wall. The furnace wall is preferably lined with refractory material on the furnace side. The furnace wall is typically the upper wall of the furnace.

[0033] In one embodiment, the at least one inlet header and / or the at least one outlet header are installed in the apparatus above the at least one reaction tube.

[0034] Compared to conventional reformers, the inlet and / or outlet headers can be installed near the end of the at least one reaction tube, away from the fuel and combustion oxidant systems installed near the boundary / limit between the pre-reaction tube section and the main reaction tube section (where the furnace begins). This makes the spatial integration and construction of each of these elements more convenient.

[0035] In one embodiment, the furnace is a top-fired furnace and the pre-reaction tube portion is an upper portion of the at least one reaction tube.

[0036] In one embodiment, the apparatus includes a plurality of reaction tubes, each comprising a catalyst material configured to promote an endothermic reaction. A furnace is arranged to heat each of the reaction tubes radiatively and / or convectively. Each of the plurality of reaction tubes includes a tube inlet for preheating a gas feed, a main reaction tube portion, and a pre-reaction tube portion disposed between the tube inlet and the main reaction tube portion. Each pre-reaction tube portion extends outside the furnace, and each main reaction tube portion extends within the furnace. A portion of each catalyst material extends within the pre-reaction tube portion.

[0037] In one embodiment, the apparatus, particularly each of the plurality of reaction tubes, includes a plurality of heat exchanger channels arranged to remove product gas generated by the endothermic reaction from each of the plurality of reaction tubes and transfer heat from the product gas to at least a portion of the catalyst material. In particular, each of the plurality of heat exchanger channels is arranged within each of the plurality of reaction tubes. Preferably, each of the plurality of heat exchanger channels extends through at least a portion of the catalyst material within each of the plurality of reaction tubes. The plurality of heat exchanger channels have, for example, a coiled or spiral shape.

[0038] The present invention also relates to the use of the apparatus described above for a cracking reaction of an ammonia feed as the gas feed. In particular, the pre-reaction tube section is arranged to perform a pre-cracking reaction on the preheated ammonia feed, thereby obtaining a partially converted ammonia stream, and the main reaction tube section is arranged to perform a further cracking reaction on the partially converted ammonia stream, thereby forming a cracked gas comprising hydrogen, nitrogen, and possibly unconverted ammonia.

[0039] The invention also relates to the use of a device as described above for converting a hydrocarbon feed into a hydrogen-containing synthesis gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other characteristics, details and advantages of the invention will become more apparent upon reading the following detailed description and several embodiments provided purely by way of example and indication, with reference to the accompanying schematic drawings, in which:

[0041] Figure 1 A device for carrying out an endothermic process according to the prior art is shown.

[0042] Figure 2 An apparatus according to the invention is shown according to one embodiment.

[0043] Figure 3 Shown Figure 2 More details of the embodiments. DETAILED DESCRIPTION

[0044] Figure 1 A reformer according to the prior art is depicted. The reformer includes one or more catalyst-filled reaction tubes 2 extending through a furnace 1. Each tube includes an inlet (not shown) and catalyst material 10 (shown by hatching in the figure). The reformer is a top-fired reformer, and a burner 3 is part of the fuel and combustion oxidant system mounted on the top of the furnace 1. The burner 3 heats the furnace 1, driving the endothermic reforming reaction forward. A top-level equipment chamber 4 houses an inlet header 5 and an outlet header 6 for supplying hydrocarbon feed to the tubes 2 and exhausting the synthesis gas produced by the endothermic reaction. A combustion air header 7 is housed in the same top-level equipment chamber 4 and supplies combustion air as an oxidant gas to the burners for combustion of the fuel. The fuel is supplied to the burners 3 via a fuel header 8. For simplicity, only one inlet header 5, one outlet header 6, one combustion air header 7, and two fuel headers 8 are shown. The nozzles of the burners 3 are directed toward the interior of the furnace 1 to produce flames within the furnace 1. The interior of the furnace 1 constitutes a radiant and convective chamber in which convective and radiant heat is transferred from the flame to the tubes 2 and ultimately to the catalyst material in each tube.

[0045] Each reactor tube 2 includes a tubular heat exchanger channel 9 extending through the catalyst material, which is used to discharge the syngas from the lower portion of the tube to the outlet header 6. The discharged hot syngas further transfers heat to the catalyst material, thereby reducing heat loss through the syngas. For simplicity, only one heat exchanger channel 9 in each tube is schematically represented by a curve. Each tube can include more than one heat exchanger channel. The heat exchanger channels typically have a coiled shape.

[0046] Figure 2 is a schematic diagram of an embodiment of an ammonia cracker of an apparatus according to the present invention. Here again, for simplicity, only one inlet header 25, one outlet header 26, one combustion air header 27, and two fuel headers 28 are shown. Ammonia feed is provided and preheated in preheater 11. The superheated feed leaves the preheater and enters cracker unit 12.

[0047] Figure 3 The details of the cracker unit are shown. It is similar to the Figure 1 The differences in the reformers are explained below.

[0048] The inlet of each reaction tube is fluidically connected to the preheater 11. In this embodiment, the reaction tubes 22 are 14 meters long. A six-meter section 33 of the reaction tubes 22 extends outside the furnace 21, while an eight-meter section 34 of the tubes extends within the furnace 21 and is directly heated by the furnace 21. The cracker unit includes a top-level equipment chamber 24. No refractory material is required within this top-level equipment chamber 24, as no burner heating occurs therein. Generally speaking, the amount of refractory material required for construction is reduced compared to prior art reformers. The furnace 21 is separated from the top-level equipment chamber by a furnace wall 32, which is lined with refractory material on the sides of the interior of the furnace 21. The reaction tubes 22 extend through the furnace wall 32. The furnace wall 32 demarcates the tube sections 33 and 43. In this embodiment, the combustion air manifold 27 and fuel manifold 28, as well as the burners 23 and the rest of the fuel and oxidant systems, can be relocated below the inlet and outlet manifolds 25 and 26. This solves the main practical problem of space integration in the top equipment chamber 24.

[0049] The tubes 22 are filled with catalyst material 30 to a level above the furnace wall 32. Thus, a portion of the catalyst material 30 (at an upstream location relative to the gas circulation in the tubes 22) extends outside the furnace 21 and is therefore not directly heated by the furnace 21. When the preheated gas feed enters the portion 33 of the tubes outside the furnace 21, some cracking will begin due to contact between the superheated ammonia feed and this upstream portion of the catalyst material 30. The portion 33 of the tubes 22 extending outside the furnace 21 serves as a pre-cracker, in which a partially cracked gas comprising ammonia, nitrogen, and hydrogen is produced, while the portion 34 of the tubes within the furnace serves as a main cracker, in which the partially cracked gas is further cracked to obtain a cracked gas.

[0050] The upstream portion of the catalyst material 30 can be different from the downstream portion of the catalyst material to accommodate different heating conditions compared to the downstream portion of the catalyst material 30 that is heated directly by the furnace. A different active catalyst material can be selected than the active catalyst material in the downstream portion of the catalyst material. For example, ruthenium can be selected for the upstream portion of the catalyst material because ruthenium has a higher catalytic activity at lower temperatures, while nickel can be selected for the downstream portion of the catalyst material. Alternatively, nickel can be selected for both the upstream and downstream portions, but the upstream portion can contain a higher weight percentage (wt%) of nickel than the downstream portion.

[0051] Here, each reaction tube 22 also includes a tubular heat exchanger channel 31 for discharging cracked gas and heating the catalyst material 30 by the discharged hot cracked gas. For simplicity, only one heat exchanger channel 31 is shown in one tube, but here, each tube may include more than one heat exchanger channel. Figure 3In the embodiment, the upper portion of the heat exchanger channel 31 extends through the upstream portion of the catalyst material 30, thereby heating this upstream portion. This increases the degree of precracking even outside the tube length / section directly heated by the furnace 21. Compared to prior art adiabatic crackers, the precracking conversion rate is improved. The shape of the heat exchanger channel 31 can be optimized for each section 33, 34 of the tube 22. For example, a coiled or spiral shape can be selected for the section 33 of the tube extending outside the furnace 21 to increase heat transfer from the hot exhaust cracked gas to this section of the tube, while a straight tubular channel can be selected for the section 34 of the tube extending inside the furnace 21.

[0052] The present invention has been described in detail in the context of an ammonia cracker, but it should be noted that the present invention also encompasses devices and uses thereof for other endothermic processes, such as hydrocarbon reforming.

Claims

1. A device for endothermic reaction of a gas feed, comprising: - a preheater (11) arranged for preheating the gas feed, - at least one reaction tube (22), a furnace (21) arranged for radiative and / or convective heating of the at least one reaction tube (22), The at least one reaction tube (22) is at least partially filled with a catalyst material (30) configured to promote an endothermic reaction, the at least one reaction tube (22) comprising: - a pipe inlet for said preheated gas feed, a main reaction tube section (34) extending inside the furnace (21) and a pre-reaction tube section (33) extending outside the furnace (21), the pre-reaction tube section (33) being arranged between the tube inlet and the main reaction tube section (34), Part of the catalyst material (30) extends within the pre-reaction tube portion (33).

2. The device according to the preceding claim, wherein The length of the pre-reaction tube section (33) is between 30% and 80% of the length of the total reaction tube (22).

3. The apparatus according to any one of the preceding claims, comprising at least one heat exchanger channel (31) arranged to discharge product gas generated by the endothermic reaction from the at least one reaction tube (22) and to transfer heat from the product gas to at least a portion of the catalyst material (30).

4. The device according to the preceding claim, wherein The portion of the catalyst material extending within the pre-reacter tube portion (33) is an upstream portion of the catalyst material (30), and the at least one heat exchanger channel (31) is arranged to transfer heat from the product gas to at least a portion of the upstream portion of the catalyst material.

5. Device according to the preceding claim, wherein The at least one heat exchanger channel (31) is arranged to transfer heat from the product gas to only a portion of the upstream portion of the catalyst material (30).

6. The apparatus according to any one of the preceding claims, comprising at least one inlet header (25) connected to the tube inlets for supplying preheated gas feed to the at least one reaction tube (22), and / or comprising at least one outlet header (26) connected to the at least one heat exchanger channel (31) for discharging product gas resulting from the endothermic reaction from the at least one heat exchanger channel (31), wherein the at least one inlet header (25) and / or the at least one outlet header (26) are installed in the apparatus above the at least one reaction tube (22).

7. A device according to any one of the preceding claims, wherein The portion of the catalyst material extending within the pre-reaction tube portion (33) is an upstream portion of the catalyst material (30), and a downstream portion of the catalyst material (30) extends within the main reaction tube portion (34).

8. Device according to the preceding claim, wherein An upstream portion of the catalyst material (30) has a lower catalyst activation temperature than a downstream portion of the catalyst material (30).

9. Apparatus according to any one of claims 7 or 8 in combination with any one of claims 3 to 5 or according to any one of claims 7 or 8 in combination with claim 6 when dependent on any one of claims 3 to 5, wherein The at least one heat exchanger channel (31) extends through a downstream portion of the catalyst material (30) and through at least a portion of the upstream portion of the catalyst material (30), the at least one heat exchanger channel (31) having a first shape in the downstream portion and a second shape different from the first shape in the upstream portion.

10. Apparatus according to any one of claims 7 or 8 in combination with any one of claims 3 to 5 or according to any one of claims 7 or 8 in combination with claim 6 when dependent on any one of claims 3 to 5, wherein The at least one heat exchanger channel (31) is arranged to transfer heat from the product gas only to a downstream portion of the catalyst material (30).

11. An apparatus according to any one of the preceding claims, comprising a fuel and combustion oxidant system arranged for burning fuel and oxidant gas in a furnace (21), wherein The furnace (21) is defined by a furnace wall (32), the pre-reaction tube section (33) is delimited from the main reaction tube section (34) by the furnace wall (32), and the fuel and combustion oxidant system is mounted on the furnace wall (32).

12. The device according to any one of the preceding claims, wherein The furnace (21) is a top-fired furnace, and the pre-reaction tube portion (33) is the upper portion of the at least one reaction tube (22).

13. Use of the device according to any one of the preceding claims for carrying out a cracking reaction of an ammonia feed.

14. Use of the apparatus according to any one of claims 1 to 12 for converting a hydrocarbon feed into a hydrogen-containing synthesis gas.

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