WO2017198706A1

WO2017198706A1 - Non-leak ammonia container for motor vehicle

Info

Publication number: WO2017198706A1
Application number: PCT/EP2017/061836
Authority: WO
Inventors: Anita Kouakou; Yazid BELKHELFA; Philippe GALABERT
Original assignee: Plastic Omnium Advanced Innovation And Research
Priority date: 2016-05-17
Filing date: 2017-05-17
Publication date: 2017-11-23
Also published as: EP3458770A1

Abstract

The gas storage container (112) for a vehicle on-board system comprises a canister (114) configured to house a solid medium able to store gas by adsorption and/or by absorption and to release the gas by desorption and a gas absorbing and/or adsorbing element comprising a material able to trap the gas and extending, at least in part, around the canister and a spacer interposed between the canister (114) and the absorbing and/or adsorbing element so as to form a gas diffusion layer defining a free space between the canister (114) and the element that is absorbing and/or adsorbing towards the gas.

Description

Anti-leak ammonia container for a motor vehicle

The invention relates to gas storage containers, more particularly ammonia or hydrogen, for an embedded system of a vehicle.

It is known, in order to reduce the emissions of nitrogen oxides of a vehicle, to inject ammonia gas into an exhaust line of this vehicle in order to generate, in the exhaust duct, a chemical reaction. reduction method according to the selective catalytic reduction method also known by the acronym SCR (selective catalytic reduction). At the end of this reaction, the nitrogen oxides are reduced in water and in dinitrogen.

Ammonia can be stored in gaseous form in a container. In this case, the container comprises a sealed cartridge which contains a solid medium, generally formed of grains of material, which is capable of storing the gas by adsorption and / or absorption and to release the gas by desorption. Heating means, such as a metal rod penetrating into the cartridge, make it possible to release the gaseous ammonia which rushes into a conduit leading to the exhaust line of the vehicle.

However, the sealed cartridge may be damaged during use of the vehicle and an unwanted leak path may appear in the cartridge. Thus, gaseous ammonia can be released into the external environment of the vehicle.

An object of the invention is to provide a safer gas storage container.

For this purpose, according to the invention, a gas storage container is provided for an onboard system of a vehicle, characterized in that it comprises:

at least one cartridge configured to receive a solid medium capable of storing the gas by adsorption and / or absorption and to release the gas by desorption,

at least one absorber element and / or gas adsorber comprising a material capable of trapping the gas, and extending at least partially around the cartridge, and

at least one spacer interposed between the cartridge and the absorber and / or adsorber element so as to form a gas diffusion layer by defining a free space between the cartridge and the absorber element and / or adsorber vis-à-vis some gas.

Spacer means any means or element for maintaining a spacing or a free space between the cartridge and the absorber element and / or adsorber. In a particular embodiment, all the spacers may be of identical geometry and size. In another particular embodiment, the spacers may be of different geometry and dimensions.

Thus, it is proposed to provide one or more free spaces for gas diffusion between the cartridge and the absorber element and / or adsorber. With such an architecture, in the event of a gas leak from the cartridge, the gas will win the free space (s) of diffusion and be trapped in the absorber element and / or adsorber. This prevents the release of ammonia out of the container. It is noted here that the invention is not therefore to avoid at all costs (ie seal or seal) a gas leak out of the cartridge. Rather, in the presence of a leak, it aims to diffuse the gas from this leak inside the container so as to allow the greater part of the absorber element and / or adsorber to capture the gas that would leak out. of the cartridge. This therefore increases the life of the container.

In a particular embodiment, the free space according to the invention contains a volume of air. Alternatively, the free space may comprise a moist gas, for example moist air, or a liquid such as water.

Preferably, the container comprises a sheath disposed between the cartridge and the absorber and / or adsorber element, the sheath having at least one orifice placing the cartridge in communication with the absorber and / or adsorber element.

The sheath thus contributes to orienting the leaking gas from the cartridge. In addition, this sheath allows the communication of the cartridge and the absorber element and / or adsorber while maintaining the different parts of the container. The robustness of the whole is thus reinforced.

Preferably, the sheath comprises a grid.

According to one embodiment, the sheath has a plurality of orifices forming, preferably, a regular mesh.

Advantageously, the sheath forms said at least one spacer.

Preferably, said at least one spacer is in direct contact with the cartridge and the absorber and / or adsorber element.

According to one embodiment, the cartridge comprises said at least one spacer. In this way, the compactness of the container is increased.

Preferably, the cartridge has a longitudinal end having a greater radial dimension than a dimension of a middle portion of the cartridge with reference to an axis of the container, said longitudinal end forming said at least one spacer.

In this way, the free space is easily delimited.

Preferably, the absorber element and / or adsorber comprises said at least one spacer.

Thus, the compactness of the container is also increased.

Note that when it is stated that the spacer is carried by the cartridge or the absorber element and / or adsorber, this means that the spacer can be manufactured in one piece with the cartridge or the absorber element and or adsorber or be attached thereto by fastening means. Advantageously, the absorber and / or adsorber element comprises a filtering layer extending, at least partially, around the material capable of trapping the gas, the filtering layer being able to let the gas gain the material capable of trapping the gas while preventing water from gaining material capable of trapping gas.

Thus, the material capable of trapping the gas is protected and its useful life is increased.

Advantageously, the filtering layer is part of an organ totally confining the material capable of trapping the gas.

The volume occupied by the material capable of trapping the gas is then constrained.

According to one embodiment, the container comprises an envelope separating the material and the cartridge and having at least one longitudinal rib extending in the direction of the cartridge.

This rib thus forms the spacer. In this way, we simply delimit the free space.

Preferably, the free space has a thickness of between 5 and 20 mm.

Such a range of thickness ensures satisfactory operation of the container while limiting its size.

Advantageously, the material capable of trapping the gas is a superabsorbent polymer material such as sodium polyacrylate or a mixture of sodium polyacrylate and water.

It is expected that the superabsorbent polymer material is capable of absorbing 500 to 1000 times its mass in 1 minute.

Preferably, the superabsorbent polymer material is in the form of a gel.

Alternatively, the material capable of trapping the gas is an adsorbent material having a specific surface area of between 100 and 2400 m ² / g, preferably between 500 and 1600 m ² / g.

Advantageously, the adsorbent material is selected from the group of materials consisting of a carbon-based adsorbent such as an activated carbon or graphite, alumina, preferably activated alumina, silica, preferably in the form of a gel. silica, a zeolite, an organometallic skeleton structure (MOF) and an amine complex of metal salt.

According to one embodiment, the cartridge comprises a solid medium capable of storing at least one of the following gases: ammonia or dihydrogen.

It is also provided according to the invention an on-board vehicle system comprising at least one container as described above, and a solid medium capable of storing the gas by adsorption and / or absorption and to release the gas by desorption, the container being in communication of fluid with a vehicle exhaust duct. Four embodiments of the invention will now be described by way of nonlimiting examples using the following figures:

FIG. 1 is an exploded perspective view of an onboard system of a vehicle according to a first embodiment of the invention,

FIG. 2 is a view in axial section of one of the containers of the system of FIG. 1,

FIG. 3 is a cross-sectional view of a container according to a second embodiment of the invention,

FIG. 4 is an axial sectional view of a container according to a third embodiment,

FIG. 5 is a schematic representation of an on-board system of a vehicle according to a fourth embodiment of the invention, and

- Figure 6 is an axial sectional view of a container according to a variant of the invention.

FIG. 1 shows an on-board system 100 of a vehicle according to a first embodiment of the invention.

The embedded system 100 includes a container 112 for storing gas, here ammonia. According to a variant of the present embodiment, the container serves to store gaseous dihydrogen. In the remainder of the description, the characteristics of a system described in relation to gaseous ammonia will be valid for gaseous hydrogen, unless otherwise specified.

The container 112 comprises two separate cartridges 114, which contain a solid medium which is capable of storing the gas by adsorption and / or absorption and to release the gas by desorption. The solid medium comprises a salt, such as a salt of strontium chloride, barium chloride, calcium chloride or a mixture of these three salts. The solid medium is therefore in the form of grains of material, but any solid substrate capable of storing ammonia can be used. When the solid medium is heated above a predetermined temperature, it releases the ammonia by desorption. Conversely, when the temperature decreases, the solid medium adsorbs and / or absorbs ammonia gas.

The two cartridges 114 are identical and have a substantially cylindrical shape with symmetry of revolution around their respective longitudinal axes. They form a rigid envelope capable of confining the solid medium. In addition, each cartridge 114 is liquid and gas tight.

In general, each cartridge 114 has at least one longitudinal end of which a radial dimension is greater than a dimension of a middle portion of the cartridge 114, with reference to an axis of the container 112, here an axis longitudinal axis of the cartridge 114.

For this purpose, as illustrated in FIG. 2, the cartridge has a proximal end, here on the left, flared in a truncated cone and wider than the rest of the cylindrical cartridge. It forms a spacer between the cartridge and an absorber element and / or adsorber of the container 112 as will be seen below.

In addition, the embedded system 100 comprises means for heating the cartridges 114. These means here comprise a metal rod 116 per cartridge, which is able to be heated by Joule effect. The cartridges 114 comprise an opening at one of their longitudinal ends, here the right or distal end, which allows to introduce and accommodate the metal rods 116. Thus, it ensures a uniform heating of the solid medium.

In addition, near the longitudinal ends of the cartridges which comprise the openings, two ducts 118 are arranged to bring the gaseous ammonia released by the solid medium to an exhaust line of the vehicle. Optionally, the embedded system 100 does not include the two ducts 118 and the metal rods 116 are hollow and open out so that the gaseous ammonia is introduced into the metal rods to gain the vehicle exhaust line. More generally, it is possible to use all types of means to place fluid in communication with the container 112 and the exhaust duct line of the vehicle.

Around the cartridges 114, a sheath 120 is disposed, which comprises a plurality of orifices forming a regular mesh all along the cartridge and the sheath and all around the axis. This mesh forms here a grid. These orifices are oriented in directions radial to the axis and pass through the thickness of the wall of the sheath. They have dimensions large enough to let the gaseous ammonia molecules pass. According to a variant of the present embodiment, the sheath 120 comprises only one orifice or a plurality of orifices which does not form a regular grid. In this embodiment, the sheath 120 which surrounds the two cartridges 114 is formed in one piece but there are two contiguous cylindrical compartments, having their parallel axes and accommodating the respective cartridges whole. These compartments are in contact with the surface of the respective cartridges. Of course, one can also have two separate sheaths 120, side by side, around the two cartridges 114 so that a sheath 120 surrounds a cartridge 114.

Around the sheath 120 and therefore the cartridges 114, and at a distance from them, a member 122 is disposed and completely confines a material capable of trapping the gas.

By material capable of trapping the gas is meant a medium capable of storing the latter by absorption and / or absorption in the event of leakage at the level of the cartridge 114.

It can first be an adsorbent material capable of capturing and storing the gas such as a carbon adsorbent (active charcoal and graphite), an activated alumina, a silica gel, a zeolite, an organometallic skeleton structure (MOF) or an amine metal salt complex of formula Ma (NH ₃ ) nX _y (in English "Metal Ammine salts").

Where M represents at least one metal cation selected from alkalis, alkaline earth metals and transition metals, preferably from Li, K, Mg, Ca, V, Cr, Mn, Fe, Co, Ni, Cu and Zn,

X represents at least one anion selected from fluoride, chloride, bromide, iodide, nitrate, thiocyanate, sulfate, molybdate, phosphate and chlorate,

a represents the number of metal cations per molecule of salt, y represents the number of anions per molecule of salt

n represents the coordination index between 2 and 12,

with a and y such that the electroneutrality of the complex is respected.

These are porous compounds with a large surface area. Since adsorption is a surface phenomenon, it depends on the specific surface of the material. The larger the surface area, the greater the adsorption. In the context of porous materials such as zeolites, activated carbon or silicas, the specific surface area depends on the porosity (distribution and pore size). There are several methods of characterizing the specific surface of the porous material depending mainly on the pore size. For example, it is possible to measure the adsorption capacity using the BET method (Brunauer theory, Emmett and Teller), which is a method for determining specific surfaces by adsorbing a gas on a solid surface. The specific surface of these adsorbent materials measured by BET is between 100 and 2400 m ² / g, preferably between 500 and 1600 m ² / g. Preferably, activated carbons have a specific surface area of 1600 m ² / g (measured using the BET method).

In addition to the adsorbent materials capable of capturing and storing the gas, the material capable of trapping the gas may be a material capable of storing water in the form of a solid. It is then a superabsorbent polymer, as is the case in the illustrated example. Superabsorbent polymers are polyelectrolites that form a gel in contact with water. Superabsorbents are solid particles capable of absorbing 500 to 1000 times their mass in 1 minute at a temperature of 20 ° C. This measurement was performed using deionized water as the solvent. Demineralized water has an electrical conductivity of 0.1 to 1 μ8 / οηι. Swelling is the most important property of superabsorbent polymers. It results from the affinity of the polymer for water. Placed in an excess of water, the superabsorbent polymers composed of cross-linked polyelectrolites swell and form hydrogels while preserving their properties. mechanical.

The material capable of trapping the gas is here in the form of a gel. Note that according to a variant of the present embodiment, the member 122 partially surrounds the cartridges 114.

The superabsorbent polymer material is capable of dissolving gaseous ammonia. The gel here comprises sodium polyacrylate or, advantageously, a mixture of sodium polyacrylate and water. The member 122 is in the form of a filter layer which is capable of allowing the ammonia to gain the gel layer while preventing water, or more generally liquid, from gaining the gel layer. According to one variant, the member 122 is partially configured to act as a filtering layer, in particular the walls of the member facing the longitudinal walls of the cartridges 114, whereas the other part of the member 122 is present in the form of a solid body.

Thus, in this embodiment, the container 112 comprises an absorber element which comprises the superabsorbent polymer material and the member 122 is in the form of a filter layer.

According to a variant of the present embodiment, the superabsorbent polymer is not in the form of a gel, but of a dense solid.

Advantageously, unlike the cartridges 114 which are rigid, the member 122 is flexible in order to accompany the increase in the volume of the gel when it dissolves the gaseous ammonia which has gained the layer of gel.

In addition, the cartridges 114, the sheath 120 and the member 122 confining the gel layer, are protected by a rigid outer envelope 124, which is in the form of two half-envelopes attached to one another following a plane of joint passing through the axes of the two cartridges.

The arrangement of the cartridges 114, the sheath 122 and the body 122 confining the gel layer will now be described in greater detail with the help of FIG. 2.

As previously mentioned, at least one of the longitudinal ends of the cartridge 114 has a larger radial dimension than a dimension of the middle portion of the cartridge. However, the gel layer, of cylindrical shape, confined by the member 122, has a constant thickness, in the longitudinal direction, and abuts, in one or two places, bearing on the longitudinal end or ends of the cartridge 114 Thus, as seen in FIG. 2, at least one of the two longitudinal ends of the cartridge 114 forms a spacer which defines a free space 126, filled with air, for the gas and which puts in fluid communication the longitudinal wall of the cartridge 114 with the surface of the gel layer, through the filtering layer of the member 122, facing the longitudinal wall of the cartridge 114. This free space here has a generally cylindrical shape with circular section. It forms an uninterrupted air space spanning more than half and even more than three quarters of the length of the cartridge, this space being occupied only by air. This space is closed sealingly at its two longitudinal ends.

According to variants of the present embodiment, the free space comprises moist air or water.

In addition, in this embodiment, it is the cartridge 114 which includes the spacer.

Thus, if the cartridge 114 is damaged and ammonia gas leaks from the solid medium, the gaseous ammonia passes through one or more orifices of the sheath and is then first diffused into the free space 126, then gains the layer of gel where it is dissolved. Thus, leaking ammonia gas is not likely to gain the passenger compartment of the vehicle or the outside of the vehicle. The container 112 according to the invention is therefore safer.

Note also that this technical effect is achieved when the free space 126 communicates at least one point of a surface of the cartridge 114 with at least one point of the gel layer remote one of the other.

In addition, as seen in Figure 2, the sheath 120 is positioned in direct contact with the longitudinal wall of the cartridge 114. It is here contiguous thereto and extends away from the casing 122 in the direction radial. The air gap is formed between the sheath and the envelope. Thus, the orifices of the sheath 120 put in communication the cartridge 114 and the gel layer.

The free space has a thickness of between 5 and 20 mm.

A second embodiment of the invention will now be described with reference to FIG. Only the differences with the first mode will be explained.

There is shown in Figure 3 a container 212 in section in a plane perpendicular to its longitudinal axis and showing only one of the two cartridges. The cartridge 214 here has a cylindrical shape and has a constant radial dimension along a longitudinal direction of the cartridge 214 from one to the other of its ends.

The member 222, confining the gel layer, comprises a portion, radially internal, which forms a filter as previously described. This part is opposite the longitudinal walls of the cartridge 214. In contrast, the other part, radially external, of the member 222 is rigid. In addition, it comprises four rigid longitudinal ribs 200 which extend towards the cartridge 214, without this number being in any way limiting. These ribs 200 are evenly distributed around the cartridge 214 and allow to position the cartridge 214 relative to the member 222 while providing a free space 226, filled with air, between the ribs 200 in the circumferential direction, and between the cartridge 214 and the flexible part of the member 222 in the radial direction. In this embodiment, the ribs 200 form spacers that spare the free space. Again, therefore, if an ammonia leak occurs at a point in the cartridge, the gas can enter the absorbent medium through several points of the envelope.

Thus, in this embodiment, the absorber element which comprises the member 222 comprises the spacers.

A container 312 according to a third embodiment of the invention will now be described with the aid of FIG. Again, only the differences with the first embodiment will be explained.

The cartridge has longitudinal ends which have a cylindrical outer face with circular section. They have the same diameter and this diameter is greater than that of the rest of the cartridge forming in particular its middle part. The cartridge thus has a configuration here in "dog bone". It is then possible to dispense with the sheath 120. Again, and thanks to this configuration, a free space 326 is provided between the longitudinal wall of the cartridge 314 and the gel layer 322. As in the first embodiment, the cartridge 314 includes the spacer.

FIG. 5 diagrammatically shows an onboard vehicle system 400 comprising a container 412 according to a fourth embodiment.

The container 412 comprises three cartridges 414 which are surrounded by a member 422 which confines the gel layer. A single member 422 surrounds the three cartridges 414. A free space 426, filled with air, is present between the cartridges 414, and between the cartridges 414 and the member 422. The three cartridges 414 are each connected to a heating member 402 by means of metal rods 404, 406 and 408 which merge in the vicinity of the heating member 402 to form a single metal rod 410. There is shown in Figure 6 a variant of the invention. The features mentioned below may be implemented independently of the above. However, they can also be used in combination with the aforementioned characteristics.

The container 512 comprises a cartridge 514 and a superabsorbent polymer material layer in solid form 500. A member 522 comprises a plurality of bodies 524 each forming a spacer which, between two bodies 524, provides a free space 526. In this configuration, when a leak of ammonia gas from the cartridge 514, the leak is confined in the free space 526, filled with air, compartmentalized by two bodies 524 and join the layer of superabsorbent polymer material 500.

Optionally, the bodies 524 each comprise at least one orifice so as to put in communication the air volumes delimited by two bodies 524. In this case, the plurality of bodies each forming a spacer makes it possible to stiffen the entire structure. container 512.

Of course, we can bring to the invention many changes without departing from the scope thereof.

All types of materials may be used to produce the cartridge 14, the sheath 120 or the member 122 confining the gel layer.

It is also possible to use gels of variable viscosities.

It can be provided to arrange the sheath in the form of a grid.

In addition, it will be possible to configure the sheath 120 so that it forms at least one spacer.

In addition, in the case where neither the cartridge 14 nor the absorber element comprises the spacer, it can be arranged so that it is in direct contact with the cartridge 14 or the absorber element.

Claims

1. Container (112; 212; 312; 412) for storing gas for an on-board system of a vehicle, characterized in that it comprises:

at least one cartridge (114; 214; 314; 414) configured to receive a solid medium capable of storing the gas by adsorption and / or absorption and to release the gas by desorption,

at least one absorber element and / or gas adsorber comprising a material capable of trapping gas (322), and extending at least partially around the cartridge (114; 214; 314; 414), and

at least one spacer interposed between the cartridge (114; 214; 314; 414) and the absorber and / or adsorber element so as to form a gas diffusion layer by defining a free space between the cartridge (114; 214; 314; 414) and the absorber and / or adsorber element with respect to the gas.

2. Container (112) according to the preceding claim, comprising a sheath (120) disposed between the cartridge (114) and the absorber element and / or adsorber, the sheath (120) having at least one port communicating the cartridge and the absorber element and / or adsorber.

3. Container according to claim 2, wherein the sheath forms said at least one spacer.

4. Container according to any one of the preceding claims, wherein said at least one spacer is in direct contact with the cartridge and the absorber element and / or adsorber.

The container (112; 312) of claim 1 or 2, wherein the cartridge (114; 314) comprises said at least one spacer.

Container (112; 312) according to the preceding claim, wherein the cartridge (114; 314) has a longitudinal end having a greater radial dimension than a dimension of a middle portion of the cartridge (114; 314) by reference to an axis of the container (112; 312), said longitudinal end forming said at least one spacer.

The container (212) according to any one of claims 1 to 3, wherein the absorber and / or adsorber element comprises said at least one spacer.

8. Container (112; 212; 412) according to any one of the preceding claims, wherein the absorber element and / or adsorber comprises a filter layer extending, at least partially, around the material capable of trapping the gas, the filter layer being able to let the gas gain the material capable of trapping the gas while preventing water from gaining the material capable of trapping the gas.

9. Container (112; 212; 412) according to the preceding claim, wherein the filter layer is part of a member (122) completely confining the material capable of trapping the gas.

A container (112; 212; 312; 412) according to any one of the preceding claims, wherein the gas trapable material is a superabsorbent polymer material such as sodium polyacrylate or a mixture of sodium polyacrylate and sodium polyacrylate. 'water.

11. Container (112; 212; 312; 412) according to the preceding claim, wherein the superabsorbent polymer is capable of absorbing 500 to 1000 times its mass in 1 minute.

12. Container (112; 212; 312; 412) according to any one of claims 10 and 11, wherein the superabsorbent polymer is in the form of a gel.

Container (112; 212; 312; 412) according to any one of claims 1 to 9, wherein the material capable of trapping the gas is an adsorbent material having a specific surface area of between 100 and 2400 m ² / g, preferably between 500 and 1600 m ² / g.

14. Container (112, 212, 312, 412) according to the preceding claim, such that the adsorbent material is selected from the group of materials consisting of a carbon adsorbent such as an activated carbon or graphite, alumina, preferably activated alumina, silica, preferentially in the form of silica gel, a zeolite, an organometallic backbone structure (MOF) and an amine complex of metal salt.

Container (112; 212; 312; 412) according to any one of the preceding claims, wherein the cartridge (114; 214; 314; 414) comprises a solid medium capable of storing at least one of the following gases: ammonia or dihydrogen.

16. On-board vehicle system (100; 400) comprising at least one container (112; 212; 312; 412) according to any one of the preceding claims, and a solid medium capable of storing the gas by adsorption and / or absorption and releasing the gas by desorption, the container (112; 212; 312; 412) being in fluid communication with an exhaust duct of the vehicle.