WO2003089346A1

WO2003089346A1 - Transportable pressure silo

Info

Publication number: WO2003089346A1
Application number: PCT/GB2003/001667
Authority: WO
Inventors: Brian Snowdon
Original assignee: Cmh Holdings Limited
Priority date: 2002-04-17
Filing date: 2003-04-17
Publication date: 2003-10-30
Also published as: AU2003240987A1; GB0208728D0

Abstract

A method of transporting a bulk material includes the use of a pressurisable conveying vessel as the transporting container. The material is loaded into the vessel which is then moved to a site where it is to be used or stored. The vessel may be pressurised to discharge its contents either all at once or in discrete portions. Apparatus for carrying out the method is also disclosed.

Description

TRANSPORTABLE PRESSURE SILO

Field of the Invention

This invention relates to a method of conveying bulk or dense materials and to a portable storage and densephase conveying system.

Background to the Invention

Current methods of transporting and using dry granular or powdered products from a manufacturing plant to the point of use are, for example: filling of bags or containers, transporting into the processing area and unloading at point of use; filling intermediate bulk containers (EBCs), transporting to a position near to the point of use and conveying into the processing plant by use of a separate mechanical or pneumatic conveying system, the point of use being, in most cases, at a different level to the point of delivery to the factory or processing area; filling pneumatic delivery trucks, unloading from the delivery trucks by pneumatic means into, e.g. storage silos, and then unloading from the silos and dispensing to the point of use by further mechanical or pneumatic conveying systems.

Our co-pending application PCT/GBOO/02158 discloses a method of conveying a non-free flowing paste which involves the use of a vessel into which the paste is loaded and the application of compressed gas to the vessel to cause the material to flow out of the vessel. The vessel includes a conical hopper portion which, at least during discharge of the materials, forms the lower section of the vessel. The cone angle of the conical hopper portion is below a critical value required to achieve mass flow. The embodiments shown and described in PCT/GBOO/02158 relate to methods in which base material is fed from one vessel to another, then to a further vessel, during conveyance of the paste material from its origin to its final destination.

A problem with many materials, particularly so-called high value products, is that any contamination can significantly reduce their value. The contamination may arise in many different ways, for example, by exposure to air or bacteria. The use of a plurality of vessels, and the connecting and disconnecting of pipes between them increases the chance of contamination.

Statements of the Invention

According to the present invention there is provided a method of conveying a bulk material from its point of origin to a position where the material is to be stored or processed, the method comprising loading the material into a transportable, pressurisable vessel, transporting the vessel to the point of use (storage or processing) and pressurising the vessel by the application of compressed gas to the vessel so as to cause the material to flow out of the vessel. The term bulk material means any material considerable for densephase pneumatic conveying, for example, powders, granules or liquids. The bulk material is preferably not a paste and if a powder or in granular form, it is preferably dry.

The method of the invention enables material to be loaded into containers at, for example, a manufacturing plant, the containers may then be sealed for transport, unloaded at the point of use without exposure to air or contaminants, and then the material may be conveyed by densephase pneumatic conveying direct to the point of use with minimal exposure to contamination or breakage. A single vessel may serve as the transporting container and a pressurised conveyor of the material, once transported, into storage or for processing.

The term "densephase" pneumatic conveying is a method of pneumatic conveying where the speed or velocity of the conveying gas in the conveying pipe is lower than the velocity required to "carry" the product in an air stream. At low conveying gas velocities, for example 2 to 15 metres per second, the material forms plugs of material that are "pushed" through the pipeline relatively slowly.

The present invention also provides apparatus for conveying a bulk material, the apparatus comprising a vessel capable of being pressurised by compressed gas, the vessel having a material inlet, a material outlet and a pipe connected to said material outlet, and gas supply means for supplying a compressed gas to said vessel to cause the material to flow out of the vessel by said outlet and along said pipe.

Furthermore, the apparatus of the invention also enables the vessel to be used as a sealed temporary storage device either at the manufacturing site or at the point of use.

The vessels may, for example, be in the form of a pneumatic conveying vessel inside a frame, which is transportable as a standard 20ft ISO container (see Fig.. 1). The container can be filled either in a horizontal, vertical or inclined position, transported to the point of use by, e.g. road vehicle, rail or ship, and then stood on its end for unloading by compressed gas at the point of use.

The container could also be in the form of a standard forklift pallet size container that would be filled, transported and used in the vertical position (see Fig.. 2).

The vessel may also be used when a product has to be transported to a factory from a manufacturing plant and a weighed quantity must then be conveyed into a process vessel (see Fig.. 3). The product being handled will have minimal contact with air or contaminants.

The system of the invention is advantageous in that fragile products or granules could be transported from the manufacturing or storage plant with very low product breakage due to it not being moved from one device or storage point to another a number of times as would be the case with conventional methods.

Another feature of the system is that it combines a storage and transport device with a densephase pneumatic conveying system which is capable of moving products from the place of product manufacture, direct to the point of use within a processing plant. The point of use may be, for example, at a higher or lower level than the material delivery point to the plant. With conventional methods, such as those using IBCs or bags, the material has to be discharged by gravity into an additional conveying system which may be a mechanical or pneumatic system.

Another use of this transportable vessel is the transport, storage and conveying of materials which cannot be pumped by conventional fluid pumps. They may for example contain solids, which could be damaged by pumps. These could be products such as yoghurts or other foodstuff for example. The action of pressurising the transportable vessel with gas and raising the fluid pressure in the vessel so that it will be pushed through the discharge pipe to the point of use will cause very little product damage compared with conventional pumping methods.

Description of the Drawings The accompanying drawings illustrate examples of the present invention and are as follows :-

Fig. la to lc shows three views of a vessel in accordance with the present invention;

Fig. 2a to 2b is a schematic representation (two views) of another vessel of the invention together with a forklift truck (Fig. 2a); and

Fig. 3 is a schematic representation of a material being transferred from the vessel of Fig. 2 to a process vessel.

Detailed Description of the Invention The present invention will now be described in further detail, with reference to the accompanying drawings.

Referring to Fig. 1 of the accompanying drawings, a transportable vessel 1 is in the form of a pressure vessel having a circular cylindrical main body portion 1 a, a domed end portion lb and a conical hopper portion lc, which forms the other end of the vessel. The vessel 1 is located within a standard ISO container-sized frame 2. Vessel 1 is provided with a filling hatch 3 in the circular cylindrical portion la. Filling hatch 3 is located very approximately centrally between dome end portion lb and upper portion lc and such that it is an in an uppermost position when the vessel is horizontal as illustrated in Fig. la. This uppermost position is achieved by the positioning of the filling hatch 3 relative to the fastening elements Id extending between the frame 2 and the vessel 1. These fastening elements Id serve not only to maintain the vessel 1 securely within the frame 2 but also to maintain it in position with the filling hatch in the uppermost position when the vessel is horizontal.

The filling of vessel 1 can take place while the vessel is located on a standard container transport road vehicle or rail wagon and this can be at the point of production of the material.

Once the filling hatch 3 has been closed the vessel 1 may be transported by standard container handling methods to the point of use. At its destination, the vessel may be put into the vertical position shown in Fig. lb. A compressed gas supply 4 is connected as is also a discharge hose 5. Discharge hose 5 is connected to a conveying pipe which enables the material within the vessel to be pneumatically conveyed to a fixed storage facility such as a hopper within a factory or process plant or to a small hopper which can be refilled by part emptying the transportable vessel 1.

To operate the vessel, it is pressurised by opening valve 6 in the compressed gas supply line 4. As a result the vessel 1 becomes pressurised. Isolating valve 7, located at the hopper end of vessel 1, is opened and the material is conveyed by densephase pneumatic conveying to the point of use.

When the vessel 1 is empty, indicated by level control 8 or by a weigh system under the vessel frame, the conveying valve 7 is then shut and the vessel 1 is de- pressurised. This may be achieved by allowing the vessel pressure to vent down the conveying pipe to the material receiving point within the processing apparatus or by a separate vent valve and pipe (not shown).

The above-mentioned valves may be manually operated or may be automatically controlled so that the vessel operation can be controlled remotely or by a control system. The arrangement for introducing conveying gas into the vessel may also include fluidising points near the vessel outlet and/or means for introducing gas into the conveying pipe. The precise method and point of gas introduction may be dependent on the characteristics of the material being conveyed.

An alternative arrangement for the vessel within the ISO-frame is a vessel with a frame on one side only and with legs to allow it to stand vertically. The frame on one side of the vessel may allow it to be loaded by a purpose built vehicle from a vertical position at ground level into a horizontal position using cables to tilt the vessel from the vertical position and then to haul it on to the vehicle. Such a method could also be used to move the vessel from the vertical position on to a road vehicle. The vessel may then be filled by gravity whilst on the back of the vehicle and then unloaded into the vertical position at the point of use.

Referring to Fig. 2 of the accompanying drawings, there is represented a smaller pallet sized vessel 9 having legs 9 secured to a base frame 10. There is a sealable filling hatch 11 and a discharge valve 12. Vessel 9 is capable of being handled by means of a forklift truck 13. After the vessel has filled with material it may be transported to the point of use.

Referring to Fig. 3 of the accompanying drawings, there is illustrated the vessel 9 shown in Fig. 2 which has now arrived at its point of use. The hose 13 has been connected to the vessel outlet together with a compressed gas supply 14. Vessel 9 is pressurised and the contents, or part Of the contents, conveyed to the process vessel or storage hopper 15 which is provided with a gas vent 17. Part of the contents may be transferred from vessel 9 as indicated and controlled by a weigh platform 16. The method of the present invention may be applied to the transport of many materials where contamination, whether by exposure to air or to other contaminants, is a problem. Among many possible examples of the use of the present invention are the following: -

(a) The transport of citric acid powder for use in the preparation of cola drinks. The citric acid powder may be loaded into a vessel and sealed. It may then be transported without exposing the contents of the vessel to the environment until the vessel reaches its destination. Furthermore citric acid material can be discharged a little at a time into the processing vessel. If it is transported by means of a standard road tanker, the whole of the contents has to be discharged in one single operation.

(b) The transport of heavy bulk ore by ship into a destination port. Previously this has been undertaken using open trucks which deliver into warehouses and from which the ore has to be then lifted into storage silos. (c) The fransport of porridge oats involves substantial bulk loads and it is often difficult to keep them sufficiently well sealed during transport. Furthermore this material is difficult to discharge out of standard oil tankers. A further advantage is that material may be discharged a portion at a time from the vessel used in the present invention whereas, with standard oil tankers, the whole of the content has to be discharged in one operation.

Claims

1. A method of conveying a bulk material from its point of origin to a position where the material is to be stored or processed, the method comprising loading the material into a transportable pressurisable vessel, transporting the vessel to the point of use (storage or processing) and pressurising the vessel by the application of compressed gas to the vessel, so as to cause the material to flow out of the vessel.

2. A method according to Claim 1 wherein the material is in the form of a powder, granules or a liquid.

3. A method according to Claim 2 wherein the material is a dry powder or in dry granular form.

4. A method according to any of the preceding claims wherein the vessel is sealed against the ingress of contaminants.

5. A method according to any of the preceding claims wherein the compressed gas is compressed air.

6. A method according to any of the preceding claims where the vessel is provided with an inlet and an outlet, the loading of the material into the vessel being via the inlet and the flow of the material out of the vessel being via the outlet.

7. A method according to any of the preceding claims wherein the vessel has a conical shaped outlet.

8. A method according to Claim 7 wherein the outlet is connected to a conduit which leads to the final desired destination of the material.

9. A method according to any of the preceding claims wherein the vessel includes a conical hopper portion, which, at least during discharge of the material, forms the lower section of the vessel.

10. A method according to Claim 9 wherein the lower conical hopper portion is the outlet end of the vessel.

11. A method according to Claim 10 wherein the cone angle is below a critical value required to achieve mass flow.

12. A method according to Claim 10 wherein the compressed gas is applied at least to the surface of the material.

13. A method according to any of the preceding claims wherein the vessel is adapted to fit in an ISO container frame.

14. A method according to any of the preceding claims wherein the vessel is transported in a horizontal position.

15. A method according to claim 14 wherein the vessel is turned from the horizontal position through about 90° to ensure that the centre line of the vessel is vertical when material is being discharged from the vessel.

16. A method according to any of the preceding claims wherein the only transport of said material, other than during its disposal, is within said vessel.

17. Apparatus for conveying a bulk material, the apparatus comprising a vessel (1) capable of being pressurised by compressed gas, the vessel having a material inlet (3), a material outlet (7) and a pipe (5) connected to said material outlet, and gas supply means (4, 6) for supplying a compressed gas to said vessel to cause the material to flow out of the vessel via said outlet and along said pipe.

18. Apparatus according to claim 17 wherein the vessel is adapted to withstand a pressure of between 4 and 8 bar.

19. A vessel according to claim 17 or claim 18 in which the vessel is housed in an ISO container frame.