AU2017295491A1

AU2017295491A1 - Compact methanol reformer for a submarine

Info

Publication number: AU2017295491A1
Application number: AU2017295491A
Authority: AU
Inventors: Stefan Krummrich; Marc Pein; Dennis Ruser
Original assignee: ThyssenKrupp AG; ThyssenKrupp Marine Systems GmbH
Current assignee: ThyssenKrupp AG; ThyssenKrupp Marine Systems GmbH
Priority date: 2016-07-13
Filing date: 2017-07-04
Publication date: 2019-01-31
Anticipated expiration: 2037-07-04
Also published as: EP3484607B1; KR20190018164A; WO2018011026A1; ES2795661T3; AU2017295491B2; EP3484607A1; KR102228364B1; DE102016212757A1

Abstract

The present invention relates to a methanol reformer (10) having a reaction region (20), a charging region (30) and a discharge region (40). The reaction region (20), the charging region (30) and the discharge region (40) are arranged one above the other with the reaction region (20) at the bottom. At least one first coaxial reaction tube (50) is arranged vertically in the reaction region (20), the at least one first coaxial reaction tube (50) having an outer tube region (52) and an inner tube region (54), the outer tube region (52) being filled with a catalyst. The outer tube region (52) is connected to the charging region (30) and the inner tube region (54) is connected to the discharge region (40). A preheating device (100) for preheating the methanol-water mixture is disposed in the reaction region (20).

Description

Compact methanol reformer for a submarine

The invention relates to a methanol reformer for the generation of hydrogen for use in a fuel cell, in particular for use of the methanol reformer on board a water-craft, in particular on board a submarine.

Modern submarines, for example submarine of the class U 212A, have a fuel cell for the generation of energy. Generation of energy is thus possible independently of external air, thus in particular when the submarine is submerged. Currently the hydrogen for this is transported in metal hydride stores, which facilitates safe carrying along of hydrogen.

However, for larger submarines than the vessels of the class U 212A, it may be useful to fall back on methanol instead of metal hydride stores. The disadvantage is that in addition a reformer has to be accommodated on board. In addition, the reformer must also meet the requirements for installation in a submarine, in particular with regard to compactness and robustness.

A heat-exchanger reactor, which comprises parallel tubes, is known from US 2010 / 0254891 A1.

A heat-exchanger reactor, which comprises parallel tubes, is known from WO 2009 / 141 517 A1.

A reactor for steam reforming is known from US 2006 / 0248800 A1.

A reformer for hydrocarbons is known from US 3,172,739 A.

A membrane for a steam reformer is known from EP 1 679 111 A2.

The object of the invention is to provide a compact methanol reformer which is suitable for use in a submarine.

This object is achieved by a methanol reformer having the features indicated in claim 1. Advantageous developments can be seen from the sub-claims, the description below as well as the drawings.

The methanol reformer of the invention comprises a reaction region, a charging region and a discharge region, wherein the reaction region, the charging region and the discharge region are ι

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- 2arranged one above the other. The reaction region is arranged at the bottom. Hence, both the charging region and the discharge region is arranged above the reaction region. At least one first coaxial reaction tube is arranged vertically in the reaction region, wherein the at least one first coaxial reaction tube comprises an outer tube region and an inner tube region. The outer tube 5 region is connected to the charging region and the inner tube region is connected to the discharge region.

Due to this construction, a structure is produced which comprises no feed inlets on the underside of the methanol reformer, but a stable and fixed base. The reformer may thus be installed well, 10 particularly in spatially confined regions, for example on board a submarine. The methanol reformer may be stored in particular in a vibration-damped and shock-safe manner and thus fulfills the particular requirements of a submarine.

Coaxial reaction tube is understood to mean two conduits with different diameter pushed into one 15 another. The diameter of the conduits is selected so that a gap is formed between the conduits.

The gap between the outer conduit and the inner conduit resulting in this arrangement is designated as outer tube region and the space in the inner conduit is designated as inner tube region.

In a further embodiment of the invention, the outer tube region is filled with a catalyst. For example intermetallic compounds, such as for example N13AI, CuZn or NiCr, noble metal catalysts, oxides, such as for example copper-zinc-aluminum mixed oxide, or metal catalysts on oxidic carriers, for example Cu/Zn, Cu/Cr or Cu/Zr on AI2O3, may be used as catalysts.

In a further embodiment of the invention, the reaction region comprises a water inlet and a water outlet. The reaction region may thus be heated or tempered using water as the heat carrier. Since the reaction of methanol and water to form hydrogen, carbon dioxide and carbon monoxide is endothermic and is effected only at elevated temperature, this is advantageous.

In a further embodiment of the invention, water is introduced as a gas through the water inlet and liquid water is discharged through the water outlet. The water inlet is for that purpose preferably arranged in the upper region of the reaction region, the water outlet in the lower region of the reaction region. In addition to the thermal capacity of the water, the enthalpy of evaporation may thus also be utilized for heating.

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- 3In a further embodiment of the invention, the reaction region, the charging region and the discharge region are arranged in a housing. It is preferably a cylindrical housing.

In a further embodiment of the invention, the discharge region is arranged above the charging 5 region. The reverse arrangement is equally possible, the further embodiments following therefrom can then be seen accordingly.

In a further embodiment of the invention, the reaction region and the charging region are separated by a first separating tray and the charging region and the discharge region are separated by a 10 second separating tray. The outer tube region is connected to the first separating tray and the inner tube region is connected to the second separating tray. As a result, the reactants flow from the charging region to the discharge region via the reaction region. In a development of this embodiment, the reaction region comprises a preheating device and a reaction device which are both connected to the charging region. The preheating device and the reaction device are 15 arranged such that the reactants first of all flow through the preheating device in the reaction region, then through the charging region, to be passed to the discharge region via the reaction device in the reaction region.

In a further embodiment of the invention, the at least one first coaxial reaction tube is arranged 20 vertically. Particularly preferably the charging region is arranged above the reaction region and the discharge region above the charging region.

In a further embodiment of the invention, the reaction region comprises a lower base, wherein the at least one first coaxial reaction tube is connected to the lower base by a screw connection. In a 25 particularly preferred embodiment, tension on the at least one first coaxial reaction tube is exerted by the screw connection with the lower base. This tension ensures that the methanol reformer exhibits higher shock resistance. A corresponding methanol reformer is thus particularly suitable for use in the military field, in particular on water-craft, in particular in underwater vehicles. Due to this effect, the lower base may be executed to be weaker and thus thinner compared to a methanol 30 reformer without tension via the at least one first coaxial reaction tube.

In a further embodiment of the invention, the screw connection connects the inner tube region to the outer tube region. The screw connection thus serves at the same time for closing the at least one first coaxial reaction tube and for diverting the gas stream from the outer tube region into the 35 inner tube region.

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- 4In a further embodiment of the invention, after removing the screw connection, the catalyst can be removed from the outer tube region or can be introduced into the outer tube region. Since the catalyst conventionally has to be changed within the service life of a reformer, the necessity of access to the outer tube region exists, which may be guaranteed easily by the screw connection. After removing the screw connection, first of all the spent catalyst may be removed from the outer tube region and then new catalyst may be introduced. Then the screw connection is re-introduced and the at least one first coaxial reaction tube is thus closed again. To feed in the catalyst, a device is preferably used which ensures that the inner tube region is not filled with catalyst.

In a further embodiment of the invention, the catalyst is arranged exclusively in the outer tube region. Due to the exclusive arrangement in the outer tube region and for example not in the charging region, a uniform temperature is achieved in the region of the catalyst and thus a uniform reaction of the methanol-water mixture. At the same time, the use of catalyst at less active regions is avoided and thus valuable catalyst saved.

In a further embodiment of the invention, the outer tube region is kept at a temperature of at least 230 °C, preferably of at least 250°C, particularly preferably of 270°C.

In a further embodiment of the invention, the outer tube region is kept at a temperature of not more than 310 °C, preferably of not more than 290°C, particularly preferably of 280°C.

In a further embodiment of the invention, the reaction region is heated using steam at a temperature of about 300°C and a pressure between 6 MPa and 10 MPa. The enthalpy of evaporation can thus be utilized for heating. At the same time, the temperature of the liquid phase, which is produced from the phase diagram of water, is set by the pressure.

In a further embodiment of the invention, at least 20 coaxial reaction tubes, preferably at least 50 coaxial reaction tubes, particularly preferably at least 100 coaxial reaction tubes, are arranged in the reaction region.

In a further embodiment of the invention, not more than 500 coaxial reaction tubes, preferably not more than 300 coaxial reaction tubes, particularly preferably not more than 200 coaxial reaction tubes, are arranged in the reaction region.

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- 5In a further embodiment of the invention, the catalyst exhibits an average grain size of at most 4 mm, preferably of 2 mm, particularly preferably of 1.5 mm. This avoids in particular bypass flows in regions not filled with catalyst.

In a further embodiment of the invention, the catalyst exhibits an average grain size of at least 0.1 mm, preferably of 0.3 mm, particularly preferably of 0.8 mm.

According to the invention, a preheating device for preheating the methanol-water mixture is arranged in the reaction region. Due to preheating within the reaction region, the methanol-water 10 mixture reaches the catalyst in the outer tube region at exactly the correct temperature of the reaction region, wherein the catalyst in the outer tube region exhibits the same temperature. The change of the temperature in the catalyst comes only due to the enthalpy of reaction.

In a further embodiment of the invention, the preheating device is connected to the charging region 15 and the preheating device comprises an inlet for the methanol-water mixture.

In a further embodiment of the invention, the preheating device consists of several heat-exchanger tubes which are each individually connected to the charging region. Each of the heat-exchanger tubes may be arranged so that the throughflow direction is predominantly vertical to the main flow 20 direction of the heating medium.

In a further embodiment of the invention, the preheating device is designed for preheating a methanol-water mixture by at least 15°C, preferably by at least 100°C, particularly preferably by at least 175°C. The use of a non-preheated methanol-water mixture at about 20°C is of course 25 particularly simple. However, this may lead to a change in the temperature of the reaction region.

The use of non-preheated methanol-water mixture is therefore advantageous for a compact overall construction, the use of preheated methanol-water mixture to simplify process control.

In a further embodiment of the invention, the preheating device for preheating a methanol-water 30 mixture is arranged in the reaction region so that new (cold) methanol-water mixture is introduced in the upper region of the reaction region, wherein the upper region of the reaction region is heated using gaseous water. The cold methanol-water mixture thus comes into contact with the steam in terms of heat engineering, wherein the steam may release a comparatively large quantity of heat to the methanol-water mixture by condensation.

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- 6In a further embodiment of the invention, the course of flow in the outer tube region runs from top to bottom. Due to the downwardly directed flow, the formation of a fluidized bed of the catalyst is avoided.

In a further embodiment of the invention, the walls of the reaction region, the walls of the charging 5 region and the walls of the discharge region as well as the at least one first coaxial reaction tube consist of the same material. They thus have the same thermal expansion properties and corrosion properties, which increases the service life of the methanol reformer.

In a further embodiment of the invention, the charging region and the outer tube region are 10 separated by a perforated plate. Escape of the catalyst into the charging region is avoided due to the perforated plate. This is particularly important since the methanol reformer is rotated in advantageous manner by 180° to fill the outer tube region with catalyst, whereby the charging region comes to rest below the reaction region. Without the perforated plate, the catalyst would be filled directly into the charging region. However, since the charging region is not heated, no catalyst 15 should be arranged here, since otherwise catalyst arranged here the methanol-water mixture would be cooled by reaction on the catalyst. This cooled gas mixture would then be released onto the catalyst in the outer tube region at too low a temperature, whereby the effectiveness of the methanol reformer would be lowered.

In a further embodiment of the invention, the methanol reformer comprises a hydrogen liberator and a burner, wherein the residual gas of the hydrogen liberator stripped of the hydrogen is supplied to the burner. Conventionally only about 90% of the hydrogen is separated off and supplied to a fuel cell, since a higher degree of separation is not economically viable. The residual gas with hydrogen and carbon monoxide is combusted using oxygen in order to at least partly 25 generate the energy necessary for the process.

The compact and stable construction of the methanol reformer of the invention makes it preferably suitable for use on board a water-craft, in particular on board a submarine.

The methanol reformer of the invention is illustrated in more detail below using an exemplary embodiment shown in the drawings.

Figure 1 schematic cross-section through a methanol reformer

Figure 2 plan view of a screw connection

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- 7Figure 1 shows a methanol reformer 10 in schematic cross-section. Figure 1 is not true to scale in order to guarantee visibility.

The methanol reformer 10 comprises a reaction region 20, a charging region 30 arranged thereabove and a discharge region 40 arranged thereabove. By way of example three coaxial reaction tubes 50, which comprise an outer tube region 52 and an inner tube region 54, are located in the reaction region 20. For example the methanol reformer 10 has 200 coaxial reaction tubes 50 which are arranged vertically in the reaction region 20. The reaction region 20 is heated by means of water which is introduced through the water inlet 60 as a gas at about 300°C and 8 MPa. The water condenses on the coaxial reaction tubes 50. For example the reaction region 20, as shown, is half filled with liquid water which is removed through the water outlet 62. The reaction region 20, the charging region 30 and the discharge region 40 are arranged in a housing 70. The reaction region 20 and the charging region 30 are separated from one another in gas-tight manner by a first separating tray 80. The charging region 30 and the discharge region 40 are separated from one another in gas-tight manner by a second separating tray 82. The outer wall of the outer tube region is connected to the first separating tray 80 so that methanol-water mixture is introduced from the charging region 30 into the outer tube region 52 which is filled with catalyst. Equally, the outer wall of the inner tube region 54 is connected to the second separating tray 82 so that reformed gas mixture may pass from the inner tube region 54 into the discharge region 40. The gas may pass through the screw connection 90 from the outer tube region 52 into the inner tube region 54. At the same time, the coaxial reaction tube is connected to the lower base 84 in shock-resistant manner by the screw connection 90. By removing the screw connection 90, the catalyst may be removed from the outer tube region 52 and the catalyst may be replaced. In order to preheat the methanolwater mixture, the methanol reformer 10 comprises a preheating device 100 which consists here by way of example of two heat-exchanger tubes. Alternatively, the preheating device may also comprise only one connection through the housing 70 and be divided only in the interior of the reaction region 20, for example into two, three or four heat-exchanger tubes. In the transition between the charging region 30 and the outer tube region 52, perforated plates 110 are arranged which allow gas through, but prevent penetration of catalyst into the charging region 30, even if the methanol reformer is rotated for charging with catalyst.

Figure 2 shows a screw connection 90 in an enlarged representation. The screw connection 90 comprises a connection 120, by means of which the outer tube region 52 and the inner tube region 54 are connected to one another so that the gas mixture reacted on the catalyst may be removed.

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- 8The connection 120 is advantageously executed so that no catalyst may pass from the outer tube region 52 into the inner tube region 54.

Reference numbers

Methanol reformer

Reaction region

Charging region

Discharge region

Coaxial reaction tube

Outer tube region

Inner tube region

Water inlet

Water outlet

Housing

First separating tray

Second separating tray

Lower base

Screw connection

100 Preheating device

110 Perforated plate

120 Connection

Claims

Patent claims

1. A methanol reformer (10) having a reaction region (20), a charging region (30) and a discharge region (40), wherein the reaction region (20), the charging region (30) and the discharge region (40) are arranged one above the other, wherein the reaction region (20) is arranged at the bottom, wherein at least one first coaxial reaction tube (50) is arranged vertically in the reaction region (20), wherein the at least one first coaxial reaction tube (50) comprises an outer tube region (52) and an inner tube region (54), wherein the outer tube region (52) is connected to the charging region (30) and the inner tube region (54) is connected to the discharge region (40), characterized in that a preheating device (100) for preheating the methanol-water mixture is arranged in the reaction region (20).
2. The methanol reformer (10) as claimed in claim 1, characterized in that the outer tube region (52) of the at least one first coaxial reaction tube is filled with a catalyst.
3. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the reaction region (20) comprises a water inlet (60) and a water outlet (62).
4. The methanol reformer (10) as claimed in claim 3, characterized in that water is introduced as a gas through the water inlet (60) and liquid water is discharged through the water outlet (62).
5. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the reaction region (20), the charging region (30) and the discharge region (40) are arranged in a housing (70).
6. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the discharge region (40) is arranged above the charging region (30).
7. The methanol reformer (10) as claimed in claim 6, characterized in that the reaction region (20) and the charging region (30) are separated by a first separating tray (80), the charging region (30) and the discharge region (40) are separated by a second separating tray (82), wherein the outer tube region (52) is connected to the first separating tray (80) and the inner tube region (54) is connected to the second separating tray (82).

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8. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the reaction region (20) comprises a lower base (84), wherein the at least one first coaxial reaction tube (50) is connected to the lower base (84) by a screw connection (90).
9. The methanol reformer (10) as claimed in claim 8, characterized in that the screw connection (90) connects the inner tube region (54) to the outer tube region (52).
10. The methanol reformer (10) as claimed in one of claims 8 or 9, characterized in that after removing the screw connection (90), the catalyst can be removed from the outer tube region (52) or can be introduced into the outer tube region (52).
11. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the catalyst is arranged exclusively in the outer tube region (52).
12. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the outer tube region (52) is kept at a temperature of at least 230°C, preferably of at least 250°C, particularly preferably of 270°C.
13. Methanol reformer (10) as claimed in one of the preceding claims, characterized in that the outer tube region (52) is kept at a temperature of not more than 310 °C, preferably of not more than 290 °C, particularly preferably of 280 °C.
14. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the reaction region (20) is heated using steam at a temperature of about 300°C and a pressure between 6 MPa and 10 MPa.
15. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that at least 20 coaxial reaction tubes (50), preferably at least 50 coaxial reaction tubes (50), particularly preferably at least 100 coaxial reaction tubes (50), are arranged in the reaction region (20).
16. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that not more than 500 coaxial reaction tubes (50), preferably not more than 300 coaxial reaction tubes (50), particularly preferably not more than 200 coaxial reaction tubes (50), are arranged in the reaction region (20).

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17. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the catalyst exhibits an average grain size of at most 4 mm, preferably of 2 mm, particularly preferably of 1.5 mm.

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18. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the catalyst exhibits an average grain size of at least 0.1 mm, preferably of 0.3 mm, particularly preferably of 0.8 mm.
19. The methanol reformer (10) as claimed in one of the preceding claims, characterized in

10 that the preheating device (100) is connected to the charging region (30).
20. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the preheating device (100) is designed for preheating a methanol-water mixture by at least 15°C, preferably by at least 100°C, particularly preferably by at least 175°C.
21. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the course of flow in the outer tube region (52) runs from top to bottom.
22. The methanol reformer (10) as claimed in one of the preceding claims, characterized in

20 that the walls of the reaction region (20), the walls of the charging region (30) and the walls of the discharge region (40) as well as the at least one first coaxial reaction tube (50) consist of the same material.
23. The methanol reformer (10) as claimed in one of the preceding claims, characterized in

25 that the charging region (30) and the outer tube region (52) are separated by a perforated plate (110).
24. The methanol reformer (10) as claimed in one of the preceding claims, characterized in that the methanol reformer (10) comprises a hydrogen liberator and a burner, wherein the

30 residual gas of the hydrogen liberator stripped of the hydrogen is supplied to the burner.