WO2011152732A1

WO2011152732A1 - Inlet/outlet system for composite pressure container

Info

Publication number: WO2011152732A1
Application number: PCT/NO2010/000199
Authority: WO
Inventors: Rune Ulekleiv; Per Vidar Hamnvik
Original assignee: Ragasco As
Priority date: 2010-05-31
Filing date: 2010-05-31
Publication date: 2011-12-08

Abstract

This invention concerns an inlet/outlet system for a composite pressure container for fluids. The inlet/outlet system comprises a boss with a valve member and/or means for reducing build-up of electrostatic charges, which system is designed to be used in a composite pressure container designed to hold fluids of both low and high pressures, such as LPG (liquefied petroleum gases), CNG (compressed natural gases), H2, and industrial gases.

Description

INLET/OUTLET SYSTEM FOR COMPOSITE PRESSURE CONTAINER

Field of invention

This invention concerns an inlet/outlet system for a composite pressure container for fluids. The inlet/outlet system comprises a boss with a valve member and/or means for reducing build-up of electrostatic charges, which system is designed to be used in a composite pressure container designed to hold fluids of both low and high pressures, such as LPG (liquefied petroleum gases), CNG (compressed natural gases), ¾, and industrial gases, the pressure container comprising an inner fluid- tight liner layer and a pressure supporting layer formed by winding fibre- reinforcement onto the liner layer in a designed pattern, as well as a central opening in one end provided with the boss for mounting a valve member, and the means for reducing build-up of electrostatic charges associated with the inner liner layer of the container, and wherein the liner layer being formed, in the area of the central opening, so as to enhance the function of the diffuser in reducing electrostatic charges.

Prior art

These types of pressure containers are disclosed in Norwegian Patent No. 306226, which is based on fibre materials being winded as a pressure supporting layer onto an inner, fluid-tight liner layer. The documents WO 9834064 and WO 9913263 also show a bottom construction and a boss mounted on top of the container. The prior art is also disclosed in Norwegian Patent No. 312048, which discloses a boss adapted to pressure containers designed to hold gases under lower pressures, like propane and butane, and in WO 05090843, which discloses a means for reducing build-up of electrostatic charges in a fluid container.

Pressure containers like these are subject to numerous and varied types of stress and forces. Mainly, this regards the inner over-pressure which may occur when filling the container with fluids, such as for instance propane. The inner pressure will influence the boss with an axially outward directed force which may be

considerable. Conversely, the boss construction may be influenced by an axially inward directed force, e.g., when a valve or coupling member is mounted to the boss, and possibly by unintended stress caused by impacts or blows. It is important that the construction and mounting/fixation of the boss is also capable of resisting such forces. The same is valid for torsion forces which may occur when for instance the valve member is mounted onto the boss, which is usually formed with treads and screwed into the boss. Torsion forces to be concerned in this regard could also occur when the fibre reinforcement is winded onto the inner liner. It is especially important that the boss provides a safe and durable sealing against the adjacent parts of the pressure container. The sealing has to be such that the above-mentioned forces are not damaging to the sealing effect. Another important issue to be considered is that the pressure container and the corresponding boss construction have to be produced rationally.

NO 212048 discloses a boss suitable for use in the present type of pressure containers. However, this boss is designed to be used in pressure containers holding fluids of relatively low pressures. Thus, there is an object of the present invention to provide an inlet/outlet system comprising a boss suitable for use in pressure containers adapted to hold both fluids of low and high pressures, and which boss is not expensive to produce.

The inlet/outlet system of the present invention may also comprise means for reducing or preventing build-up of electrostatic charges in a composite fluid container during filling of a fluid. The composite fluid container comprises electrically insulating material and a valve means for filling and discharging fluid from the container.

Electrostatic charges occur normally when a gas/liquid is flowing through a tube, valve or past other types of obstacles. When the charge is built up on an insulated surface, the charge will establish an electrical field which, if sufficiently large, will cause a discharge in the form of spark formation, if coming into contact with a conducting antipode contacting the container. The size and intensity of the discharge depend on the accumulated energy, which depend on the total charge being released. The minimum charge energy for propane will for example be 0,25 mJ for a stoichiometric mixture of 4% propane in air.

The Applicants own European Patent No. EP 0958473 discloses a pressure container for storage of fluids, such as propane. The container comprises an inner, fluid tight container and an outer, protective casing. The inner pressure container is made of a transparent and/or translucent material, whereby the liquid level of the inner container may be observed from the outside. The outer casing comprises a middle section having surface portions being cut-away, so that the liquid level inside the inner container also may be observed through the casing. Such type of containers and/or casings is made of a thermo-plastic material and composite material, comprising thermoplastic materials such as PET, PE, PA. Compared to a pressure container of metal, and provided the metal containers are earthed, pressure containers made of plastic materials do not conduct electrical and/or static potentials as good as steel containers. Such static electricity may build-up occasionally in containers of plastic materials, for example during filling of the liquid into the container. In particular, build-up of static electricity may occur during filling of the container for the first time. At such stage the container is completely empty and there exist no partial liquid pressure inside the container. Consequently, built-up of static electricity may more easily occur in containers of plastic materials when the liquid internally hit the plastic material in the container. The stronger jet, the drier air, the faster filling rate, and the higher filling velocity and pressure in the jet of fluid impacting the container wall, the higher will the electrostatic build-up be. The static charge is caused inter alia because of the friction between the jet and the container wall.

One possibility of preventing build-up of electrical potential in the container is to discharge the potential, for example by earthing the internal container during filling or by ensuring that the inner container wall is wetted prior to filling. Provided the container is earthed, such potential does not represent a problem in metal containers since the metal material in the container readily discharge the potential. For containers of plastic materials, however, build-up of static electricity may occur. Since discharge of the potential during filling operation may occur, causing the possibility of formation of sparks, the presence of such potential should be avoided. An objective of the inlet/outlet system of the present invention is to ensure that flow of fluid into the container does not cause build-up of electric and/or electrostatic charges which may produce sparks igniting the gas, in particular during filling of the container. According to the inlet/outlet system of the invention, the objective is achieved by means of a method and means for reducing build-up of electrostatic charges as further defined in the appended claims. According to the invention, a filling process is achieved in which the velocity of flow is reduced and/or that the direction of flow is changed during the filling operation without increasing the total time required for filling the container. Further, a safe method of filling combustible or inflammable fluids, such as liquid propane, butane, CNG or the like, is obtained.

Based on the disclosure above, it is provided a pressure container with an

inlet/outlet system as specified in the appended claims. Moreover, further specific features disclosed in the description and in the figures and the claims, contribute substantially to improvements for the pressure container construction.

Thus, the invention provides an inlet/outlet system for a pressure container comprising a boss with a valve means and/or a diffuser.

Short description of Figures The invention will now be described with reference to the examples which are shown in the figures, wherein:

Figure 1 shows an axial section view of the upper part of a composite pressure container with a boss mounted, the boss having a valve member mounted.

Figure 2 shows a section view of another embodiment of the boss,

Figure 3 shows a section view of a third embodiment of the boss,

Figure 4 shows a perspective view of an imbedded member of a boss,

Figure 5 shows a fourth embodiment of a boss, Figure 6 shows a boss seen from above,

Figure 7 shows a side view of a composite pressure container provided with a valve means according to the present invention; Figure 8 shows a vertical section through the valve means according to the invention, seen along the line A-A in Figure 7; and

Figure 9 shows, in an enlarged scale, the valve means indicated by the detail B in Figure 8.

Detailed description of the invention

Figure 1 shows a preferred embodiment of a boss 1 on a composite pressure container, wherein the boss is fitted to a valve 5. The boss 1 is welded or in another way fixed to an inner liner layer 4 on the pressure container with a connecting flange 11. On top of the connecting flange and the liner layer, a fibre-reinforced layer 3 is winded in a way known per se. The fibre-reinforced layer thus functions as a pressure supporting layer, both for the boss 1 and the liner layer 4. The boss and the liner layer are produced in a known way in a polymer material, preferably by spray casting and mould blowing, respectively; however, other materials may also be contemplated.

The connecting flange is fixed to the liner layer 4 through an inclined surface 14. As mentioned above, the fixation may be carried out in a known way by welding, by different gluing techniques, or by other techniques, depending on the materials used. Alternatively, for the solution shown, the liner layer may be melted together with the connecting flange to form a continuous surface toward the opening.

The boss comprises a neck part 12 having a diameter less than the diameter of the connecting flange 11, and which is placed axially outside the connecting flange and pressure container. The fibre-reinforcement is winded against the neck part, which provides for good control of the winding of the fibre-reinforcement, and prevents the fibre-reinforcement from covering the opening. The boss in addition comprises an imbedded member 2 made from a harder material then the rest of the boss 1, and which is fitted with mounting means 24, 26 for mounting valves 5 etc. From a production economic view, brass is preferred;

however, the imbedded member 2 may also be formed from other metals, possibly plastic materials, e.g., fibre-reinforced plastic.

Except for the mounting means 24, 26, the imbedded member is substantially cast imbedded in the remaining material constituting the boss. The imbedded member 2 is formed with a lower flange 21, which extends radially inside the connecting flange 11, and has a diameter exceeding the diameter of the neck part. In this way, the pressure supporting fibre-reinforcement will also cover the outer part of the lower flange of the imbedded member, and thus, prevent movement in an axial direction. In the present invention, the lower flange 21 is made wider to provide a boss which can hold higher pressures, and which then provides an inlet/outlet system according to the invention which may be used in a composite pressure container to hold not only low pressure fluids, but also high pressure fluids like CNG, H₂ and different industrial gases.

The mounting means 24, 26 preferably consist of a threaded part 24, which is formed to receive standard valve types, and a supporting surface 26 which stops the valve in the right position and thus prevents the valve 5 from being screwed in too far. To avoid differential pressures building up when a valve is screwed into the boss, the mounting means have cylindrical threaded part 24, and not conical threads.

To prevent movement of the imbedded member caused by torsion, e.g., when fixing a valve, the member is formed with gripping organs which prevent rotational movement for the imbedded member relative to the pressure container. These gripping organs 22 may be formed as holes, recesses or grooves in the imbedded member, e.g., such as shown in Figure 4. In this way, a boss is provided which may be welded to the liner layer, and which at the same time is strong enough to be fixed to existing valves or other coupling means. Thus the boss is fitted to a composite pressure container such that it has three interfaces, i.e., to the valve member, to the inner liner-layer and to the pressure supporting layer.

Normally, it is difficult to achieve adhesion between the imbedded member and the rest of the boss. Relative movement between these parts, e.g., because of sagging of the plastic parts, leads to the occurrence of a leakage point for the content of the pressure container along the interface between the imbedded member and the boss. For this reason, the boss preferably comprises a lip 23 formed from the material of the boss, which upon mounting of a valve 5 is positioned between the valve and the imbedded member. Preferably, the valve is fitted with an O-ring 51 to further improve the sealing. This lip 23 may be placed on the inside and/or the outside of the imbedded member, depending on the type of valve to be mounted. However, the sealing has to be achieved on the outside or inside of the leakage channel between the imbedded member 2 and the rest of the boss 1. Thus, the sealing between the O- ring on the valve and the boss is preferably an interface wherein the rubber O-ring is in contact with the plastic material of the boss.

In Figure 1, the boss is fitted with a lip 23 which is directed radially inward towards the valve opening of the boss, and which as shown in the example provides sealing against an O-ring 51 on the valve 5. Moreover, the lip has an upper part 25 which may provide sealing against a valve with an adjacent surface, preferably comprising an O-ring, such as shown in Figure 3.

The boss of Figure 1 is also formed with a second flange 13, which extends in a radial direction over the neck part 12. This second flange 13 is advantageous during winding on of the pressure-supporting layer because it provides good guidance of the ribbon/fibre, and because it prevents excess of adhesive from migrating towards the valve opening. In addition, the second flange 13 may be formed other than circular, such as for instance hexagonal, to provide a better grip when mounting the valve (see, Figure 6). The second flange 13 may in certain embodiments be excluded.

Figure 2 shows an example of a boss which substantially corresponds to the boss of Figure 1 , wherein the sealing lip 23 is placed in the axially lower part of the boss such that the sealing against the O-ring 51 of the valve 5 is placed before the imbedded member 2, and thus, a build up of pressure in the space between the imbedded member 2 and the rest of the boss 1 is avoided.

According to an alternative embodiment of the boss of Figure 2, only the lower part of the imbedded member 2, with the lower flange 21 of the member, may be covered by the material of the remaining part of the boss. In this embodiment, the neck part is defined by the imbedded member, and the member may be formed with an upper flange with the same function as the above-mentioned second flange 13. The sealing against a connected valve 5 may be provided with the inner lip 23.

In Figure 3, a further embodiment is illustrated, wherein the upper part 25 of the boss 1 functions as a sealing lip 23 against an axially directed O-ring 51 mounted on the valve 5, and which thus is squeezed between the valve and the imbedded member when the valve 5 is screwed into the boss.

Figure 4 shows a perspective view of the imbedded member 2 as shown in Figures 1-3. The imbedded member may be formed from hot pressed brass, which provides for low production costs; however, the member can, as mentioned above, also be produced from other materials, such as for instance fibre-reinforced plastic.

To prevent the imbedded member from being twisted when a valve or other coupling is mounted, the member is fitted with grip organs 22 which provide a grip against the surrounding plastic part of the boss 1. These grip organs may be formed in several different ways, depending on the method of production and economy, e.g., the holes may be replaced with a circumference which is not circular. Figure 5 shows a fourth embodiment, wherein the boss comprises a second flange 13, and wherein the imbedded member comprises an upper flange 27, which correspondingly to the lower flange has a diameter exceeding the diameter of the neck part 12, and which is cast embedded in the boss. This provides for a higher strength against downward directed forces, which for instance are caused by blows to the boss or by under pressure in the container.

In Figure 6, a boss 1 is shown from directly above, wherein the boss comprises a second flange 13 with a hexagonally shaped outer circumference. The embedded member 2 extends a bit further inwards than the plastic part of the boss. This is partly because of the production to avoid plastic getting in contact with the threads during cast imbedding of the embedded member, but also to form a supporting surface 26 as described above.

The diameter of the connecting flange 11 will vary according to the type of pressure container to be used, and will be adapted to the opening of the pressure container. The liner layer may consist of a tube with a bottom, wherein the connecting flange 11 constitutes the upper part of the liner layer, and thus, which has the same outer diameter as the liner layer; or, the connecting flange may be placed over the liner layer and be fixed over a bigger surface.

The production of the pressure container and the boss may be performed using well known commercially available methods. In a preferred embodiment, the pressure container is produced in a translucent material, such as disclosed in

PCT/NO98/00026.

Figure 7 shows a schematic view of a composite pressure container 60 for fluids. At its upper end, as indicated in the Figure, the container 60 is provided with a handle 61 for handling the container 60. Further, a charging and discharging valve 5 is shown, centrally arranged at the upper end of the container 60. Figure 8 shows a vertical section through the container 60 shown in Figure 7. A preferred embodiment of the valve 5 according to the invention is shown in

Figure 8 and on an enlarged scale in Figure 9. As shown in the Figures 8 and 9, the inner part 62 of the container 60 is provided with a boss 1 at its upper end. The boss 1 is designed with an upwards protruding cylindrical part 12 for housing a valve means 5.

According to the embodiment shown, such cavity 28 is formed by a downwards protruding tube shaped part 29, formed by the inner liner-layer 4 of the composite pressure container, protruding into the inner pressure tight part 62. At its lower end, the downwards protruding tube shaped part 29 is provided with one or more openings 33 extending into the inner part 62 of the container 60. The opening(s) may either be arranged in a bottom plate 30 of the downwards protruding part 29, such as shown in Figure 8 and 9, or the openings may be arranged in the side wall of the downwards protruding tube shaped part 29. The valve means 5 is formed with a preferably vertical bore 31 through the valve means 5, the bore of the valve means 5 being closed at its lower end. At said lower end the valve means 5 is provided with a plurality of openings 32, preferably extending laterally, forming an angle with the central bore 31 and communicating with said bore 31. The number of lateral bores 32 may for example be three or four. It should be appreciated, however, that the number may vary, provided that at least one change of direction of the fluid flow during the filling stage is achieved. The lower end of the valve means 5 extends preferably into the cavity 28 and the openings 32 of the valve means may possibly be arranged at a higher level than the opening(s) 33 in the cavity 28/the tube shaped part 29.

In order to avoid formation of a blocking liquid plug during filling, the opening(s) 33 may preferably have a larger total area than that of the openings 32 in the plug 5.

As shown in the Figure 8 and 9 the downwards protruding tube shaped part 29 may at its lower end be provided with a bottom plate 30, the opening 33 being arranged in the bottom plate 30. In order to form a ring shaped tray 34, the bottom plate 30 may preferably be formed with upwards protruding lip(s) 35. Further, the valve means 5 is provide with a valve body 36 made in a conventional manner and functioning in a conventional way.

During filling the container 60 a supply hose is connected to the valve means 5. The fluid to be filled into the container is then pumped into the container. The fluid will be pumped in through the central, vertical bore 31 at a pressure. At the lower end of the bore 31 the fluid will change direction and will be forced in lateral direction, out through the openings 32 in the valve means and into the tube shaped part 29 and then down into the inner part 62. When the fluid hits the wall of the downwards protruding part 29, the velocity of the fluid will be reduced and then flow down into the inner part 62 in a manner preventing build-up of electrical or electrostatic potential on the container wall. The electrical or electrostatic potential which possibly is formed will in such case be formed in the valve means 5 and may possibly in a simple manner be discharged in a known manner by means of an earthed connection.

According to the invention the entire or parts of the inner surface of the container 60 may be provided with a conducting surface or with conductors (not shown) which may be connected to the valve means 5 of metal, whereby an additional earthing is obtained when connected, for example to a earthing pin or plug on the filling station, The conducting area may preferably be arranged on the part of the interior surface of the container to be hit by the jet(s) during the filling operation.

The casing 63 may alternatively be made of an electrical conductive material. Such system may be optional, or form an additional safety measure, to the design of the valve means as described above. The material used in the valve means may preferably be of a type conducting electricity, so that the valve means may be earthed during the fluid charging or fluid discharging operation. The valve means may for example be made of metal or may be provided with a conductor connecting the downwards protruding tubular part 29 with an earthing contact attached to the filling equipment.

Further, it should be appreciated that the surrounding casing 63 may be formed as one integral part or as an assembly of several parts without deviating from the inventive idea. Even though the handle 61 according to the above described embodiment is made as an extension of the surrounding casing 63, it should be appreciated that the handle may be formed and attached to the casing in any suitable way and may be placed at any suitable position on the container 60. The present invention thus concerns an inlet/outlet system for a composite pressure container for fluids, the container comprising an inner fluid-tight liner layer 4 and a pressure supporting layer 3, as well as a central opening in one end provided with a boss 1 for fitting to a valve member 5, and means for reducing build-up of electrostatic charges, wherein the inner liner layer 4 forms an open pocket 28 around the central opening inside the container 60, onto the lower part of which pocket the means for reducing build-up of electrostatic charges is associated, such that the valve 5 mounted inside the boss 1 has one end accessible from the outside of the container and the other end inside said pocket 28.

In a more specific embodiment, the inlet/outlet system according to the invention is one wherein the sealing between the valve and the boss 1 is provided by an O-ring 51 on the valve member 5 and a non-metal material of the inner lip 23 on the boss 1.

In a further embodiment, the inlet/outlet system of the invention is one wherein the threaded part 24 of the boss is formed with cylindrical threads for fixing the valve 5.

The invention further concerns he inlet/outlet system of any of the preceding embodiments, wherein the pocket 28 is arranged in the fluid container 60 in the region of the valve means 5, and wherein openings 32 of the valve means 5 communicate with said pocket 28.

In a more specific embodiment, the inlet/outlet system of the invention is one, wherein the pocket 28 is provided with at least one opening 33 communicating with the interior 62 of the container 60.

Also comprised is an inlet/outlet system of according to the invention wherein the means comprises nozzles or openings 32 which completely or partly pulverize the liquid flow.

The inlet/outlet system of any of the present invention may also be one, wherein the openings or nozzles 32 form a turbulent flow out of said openings or nozzles 32. In an even more specific embodiment, the inlet/outlet system of any of the invention is one, wherein the nozzles or openings 32 produce a laminar flow out of said nozzles or openings 32.

Thus, the present invention in one embodiment concerns an inlet/outlet system for a composite pressure container for fluids, said pressure container being adapted to hold fluids of both high and low pressures, such as CNG, LPG, ¾ and industrial gases, the container comprising an inner fluid-tight liner layer 4 and a pressure supporting layer 3 formed by winding fibre-reinforcement onto the liner layer 4 in a designed pattern, as well as a central opening in one end provided with a boss 1 for fitting to a coupling or valve member 5, and means for reducing and/or preventing build-up of electrical and/or electrostatic potential on the interior wall of the container during filling of the container, said boss 1, which has interfaces with the valve member, the liner layers, comprising a connecting flange 11 for connecting to the liner layer 4, and a neck part 12 axially placed outside the connecting flange 11 with a chosen minimum diameter, and wherein the fibre-reinforcement 3 of the pressure container is winded against the neck part 12, wherein the boss 1 preferably is formed from a plastic material, and comprising a cast imbedded member 2 formed from a material harder than the material of the remaining parts of the boss, wherein the cast imbedded member 2 in a way known as such comprises means 24, 26 for mounting said coupling or valve member 5, and a lower flange 21 axially inside said neck part 12, wherein the lower flange 21 has a diameter bigger than the diameter of the neck part 12, wherein the means for reducing build-up of

electrostatic charges is arranged as an integral part of the upper end of the container wall in association with the valve means 5; said means substantially reducing the fluid velocity and/or changes the direction of the fluid flow during filling.

Claims

1. Inlet/outlet system for a composite pressure container for fluids, the container comprising an inner fluid-tight liner layer 4 and a pressure supporting layer 3, as well as a central opening in one end provided with a boss 1 for fitting to a valve member 5, and means for reducing build-up of electrostatic charges, wherein the inner liner layer 4 forms an open pocket 28 around the central opening inside the container 60, onto the lower part of which pocket the means for reducing build-up of electrostatic charges is associated, such that the valve 5 mounted inside the boss 1 has one end accessible from the outside of the container and the other end inside said pocket 28.

2. The inlet/outlet system of claim 1, wherein the sealing between the valve and the boss 1 is provided by an O-ring 51 on the valve member 5 and a non-metal material of the inner lip 23 on the boss 1.

3. The inlet/outlet system of claim 1, wherein the threaded part 24 of the boss is formed with cylindrical threads for fixing the valve 5.

4. The inlet/outlet system of any of the preceding claims, wherein the pocket 28 is arranged in the fluid container 60 in the region of the valve means 5, and wherein openings 32 of the valve means 5 communicate with said pocket 28.

5. The inlet/outlet system of any of the preceding claims, wherein the pocket 28 is provided with at least one opening 33 communicating with the interior 62 of the container 60.

6. The inlet/outlet system of any of the preceding claims, wherein the means comprises nozzles or openings 32 which completely or partly pulverize the liquid flow.

7. The inlet/outlet system of any of the preceding claims, wherein the openings or nozzles 32 form a turbulent flow out of said openings or nozzles 32.

8. The inlet/outlet system of any of the preceding claims, wherein the nozzles or openings 32 produce a laminar flow out of said nozzles or openings 32.