GB2110192A - Method of and apparatus for discharging flowable material from a container - Google Patents

Abstract

In order to facilitate discharge of flowable material from a container, it is provided with a collapsible member defining a fluid tight portion and expandable by the admission of a fluid to force the contents or to cause the contents of the container to flow out of an outlet of the container. The collapsible member may be a flexible sheet attached to the walls of the container or a collapsible bag and may be compartmented and arranged for sequential inflation of the compartments. The container may be a transport container or a silo. The method and apparatus are suitable for the discharge of diverse materials such as grain, fly ash or granules of expanded polystyrene.

Description

SPECIFICATION Method of an apparatus for discharging flowable material from a container This invention relates to a method and apparatus for facilitating the discharge from a container of a flowable material such as grain, fly ash, or granules of expanded polystyrene.

Due to the granular structure of these materials and, in the case of fly ash, the very small size of each particle, coagulation of the material when in bulk often occurs impeding discharge from a container in which the materials are stored, or transported by a bulk carrier such as a tanker or trailer. In particular it has been found that discharging granules of expanded polystyrene used for insulating cavity walls of buildings from a trailer used to transport such material to a building site presents special problems due in the main, to the very light weight and small size of the granules. Various methods have been tried such as blowing the granules out of a container ortrailer or tipping the trailer to discharge its contents but neither of these methods have proved satisfactory.

In accordance with this invention therefore we provide a method of facilitating the discharge of flowable material from a container by providing said container with a collapsible member which, when expanded by the admission of fluid forces the contents out of the container thereby discharging the material therefrom.

In one form of the invention the membercompris- es a flexible sheet whose edges are secured to the walls of a container so that as fluid is admitted to that part of the container enclosed by said sheet the volume thereof increases decreasing the volume in which the material is stored, thereby discharging it from the container.

In another form of the invention the collapsible member comprises a bag which when inflated by the admission of fluid thereto squeezes the contents of the container out therefrom.

We also provide means for storing or transporting flowable material comprising a container having a collapsible member defining a fluid tight portion and means for admitting to said portion a fluid to expand said member to discharge from said container flowable material stored therein.

In one particularly advantageous embodiment of this invention, we provide a trailer for transporting expanded polystyrene granules used to insulate cavity walls of buildings. The trailer comprises a rigid box-like structure to the internal walls of which is secured a flexible plastics sheet. The edges of the sheet at one longitudinal end of the trailer are secured to the upper portion of the side and back walls and the edges of the sheet at the forward or discharge end of the trailer are secured to the lower portions of the side walls and the floor. The sheet is constructed so that in the deflated position it drapes against the side walls and the bottom portion lies on the floor. The space between the sheet and the side, back walls and floor defines a fluid tight enclosure.

An entry port is located at the upper rear part of the trailer and a discharge port atthe forward end thereof. Granules of expanded polystyrene are loaded into the trailer via the entry port and discharged via the discharge port by admitting air under pressure to the space enclosed by the sheet which rises first at the rear end of the trailer and then progressively towards the forward end forming a ramp thereby causing the granules to be squeezed out of the trailer through the discharge port.

Instead of using a sheet secured to the trailer walls, a bag may be used, shaped so that on inflation it forms a ramp as described above.

By using a method of discharge as described above, the trailer can be constructed to have a lower centre of gravity than conventional trailers that employ hydraulic or mechanical tipping mechanisms which are normally located beneath the trailer body. Some trailers employ a tipping mechanism located at the forward end of the trailer which enables the centre of gravity of the body to the lowered but the length of the trailer is increased.

Furthermore, such mechanisms require to be mounted on a rigid sub-frame to which the trailer body is pivoted but using the method of discharge above described the body can be made of rigid panels without the need for a substantial sub4rame.

Thus no additional body strength is required other than that necessaryfor normal load carrying. Furthermore, the body can be made demountable so that it can be loaded at any required location and then swung onto and secured to a flat-bed railway truck or a flat-road trailer.

In order that the invention may be fully understood, preferred embodiments thereof will now be described with reference to the accompanying drawings in which: Figure lisa simplified longitudinal cross-sectional view of a trailer incorporating discharge means in the form of a bag in accordance with this invention; Figure 2 shows the commencement of a discharging operation from the trailer shown in Figure 1; Figures 3,4 and 5 show various stages in the discharge of the contents of the trailer shown in Figure 1; Figure 6 shows the trailer empty and the bag deflated; and Figure 7 shows an alternative form of bag for use in the trailer shown in Figure 1.

Referring now to Figures 1 to 6, the trailer 1 comprises a self-supporting rigid box-like structure 2 formed of plywood panels faced with glass-reinforced fibre sheets and having a rearwall 3, front wall 4, side walls 5 and a top 6. An entry part 7 is provided in the top 6 adjacent the rear wall 3 and a discharge port in the form of a hinged flap 8 in the front wail 4. The structure 2 is mounted on road wheels 9 and a towing bar (not shown) is mounted to the rear part of the trailer. An inflatable bag 10 rests on floor 11 of the box-like structure 2 and is connected to an inlet valve 12 in the rear wall 3.

The trailer is loaded with a flowable material, such as expanded polystyrene granules via the entry port 7 to fill the enclosed volume of the box-like structure 2 as shown in Figure 1. To discharge the contents of the trailer, the flap 8 is lifted which allows some of the contents to be discharged by gravity as shown in Figure 2. The bag 10 is then inflated by admitting air under slight pressure of about 1 to 2 p.s.i. through the valve 12. As the rear part of the bag inflates, as shown in Figure 3, a ramp is formed which reduces the internal volume of the structure 2 containing the granules forcing them out through the discharge port 8.Continued inflation of the bag causes it to progressively inflate towards the forward end of the trailer as illustrated in Figures 4 and 5 until all the contents have been discharged whereupon the bag is exhausted to atmosphere and collapses as shown in Figure 6.

The bag 10 may have internal divisions 13 as shown in Figure 7 to form separate compartments, each of which may either be connected to a sequence valve allowing sequential inflation of the compartments or coupled to each other by a pressure valve so that as the pressure in one compartment reaches a predetermined value the valve opens to allow the next compartment to be inflated.

The bag and its internal divisions may be made of rubberised canvas or plastics material.

Instead of using a separate bag in the trailer structure, a sheet may be used with its edges secured to the back, side walls and floor of the structure 2 to form a substantially air tight compart ment as shown in dotted lines 14 in Figure 6. The sheet comprises a rectangular back panel, two triangular side panels and a rectangular floor panel secured together so that in the deflated state the triangular side and rectangular back panels drape against the respective side and back panels of the structure 2 and the floor panel rests on the structure floor with the forward edge of the floor panel secured to the floor of the structure 2 adjacent the discharge port 8. In this embodiment part of the structure acts as part of a bag with the sheet forming the ramp to squeeze out other contents of the trailer when air under pressure is admitted to the air tight compartment.As described above with reference to Figure 7, the compartment may be formed with divisions which in this embodiment would be secured to the side walls and floor of the structure and the underside of the flexible sheet.

By controlling the progressive inflation of the bag from one end of the trailer to the opposite end, the shifting of the centre of gravity longitudinally of the trailer can be controlled to prevent excessive weight being transferred to either end thereof.

Whilst preferred embodiments of the invention have been described in connection with the dis chargeofflowable material such as expanded polystyrene granules, it will be understood that the method and apparatus is applicable to the discharge of other materials such as grain from a silo. In this latter application an annular bag may be used which in transverse cross-section is trapezoidal in shape to provide a ramp sloping from the inner cylindrical wall of the silo down to a central discharge opening in the floor. The bag may have internal divisions as described above with reference to Figure 7, the divisions being radial and/or circumferential to allow progressive inflation from the outer part of the bag to the inner central part and/or circumferentially around the bag to produce a wave-like motion to break down coagulations in the grain stored in the silo. Additionally the air may be pulsed into the bag to cause it to impart rapid vertical movements to grain stored in the silo thereby inducing it to flow towards the discharge opening. Also the inner annular section of the bag defining the discharge opening may have an expandable section to control the diameter of the opening and thereby the rate at which material is discharged.

Shapes other than annular may be used particularly where, in existing silos the discharge port is in the lower wall rather than in the centre of the floor.

Claims (15)

1. A method of facilitating the discharge of flowable material from a container having an inlet for the material and an outletforthe material, wherein the container is provided with a collapsible member expandable by the admission of a fluid to force the contents or to cause the contents of the container to flow out of said outlet thereby discharging the material from the container.

2. A method as claimed in Claim 1, wherein the fluid is air.

3. A method as claimed in Claim 1 or 2, wherein the collapsible member is subdivided into separate compartments, and wherein the compartments are progressively expanded in the direction from the inlet to the outlet.

4. A method as claimed in any one of Claims 1 to 3, wherein the member is expanded by a pulsating admission of said fluid.

5. A method of facilitating the discharge of flowable material from a container having an inlet for the material and an outlet for the material substantially as hereinbefore described with reference to the accompanying drawings.

6. A container for storing or transporting flowable material, wherein the container has an inlet for said material, an outlet for said material, a collapsible member defining a fluid tight portion and means for admitting to said portion a fluid to expand said member, said member being arranged such that upon expansion it facilitates discharge of the material through the outlet of the container.

7. A container as claimed in Claim 6, wherein the collapsible member comprises a flexible sheet, the edges of which are secured to the walls of the container and which is so arranged that, as fluid is admitted to that part of the container bounded by the sheet, the sheet expands to decrease the free volume of the container thereby discharging said material.

8. A container as claimed in Claim 6, wherein the collapsible member is an inflatable bag.

9. A container as claimed in any one of Claims 6 to 8, wherein the collapsible member is compartmented and means is provided to permit progressive expansion of the compartments from said inlet towards said outlet.

10. A container as claimed in Claim 9, wherein each compartment is connected to a sequence valve.

11. A container as claimed in Claim 9, wherein each compartment is coupled to the next by a pressure valve, the valves being graded to permit sequential inflation of the compartments.

12. A container as claimed in any one of Claims 6 to 11, wherein the container is a transport container in the form of a rigid box-like structure with an outlet flap at one end for discharge of material, and wherein the collapsible member is shaped to form, upon inflation, a ramp leading to said outlet flap.

13. A container as claimed in any one of Claims 6 to 11, wherein the container is a silo and the collapsible member is an annular bag of trapezoidal cross-section.

14. A container as claimed in any one of Claims 6 to 13, wherein the collapsible member is made of rubberised canvas or of plastics material.

15. Acontainerforstoring ortransportingflowable material substantially as hereinbefore described with reference to Figures 1 to 6 or Figure 7 of the accompanying drawings.