GB2561151A

GB2561151A - Container

Info

Publication number: GB2561151A
Application number: GB1704352.2A
Authority: GB
Inventors: Kristian Fjelldal Alf
Original assignee: Fjelldal Consulting & Eng As
Current assignee: Fjelldal Consulting & Eng As
Priority date: 2017-03-20
Filing date: 2017-03-20
Publication date: 2018-10-10
Also published as: GB201704352D0; WO2018172282A1; EP3601104A1

Abstract

A storage container 20 particularly suitable for bulk materials comprises: (i) an upper end 21 and a lower end 22 and side walls 23a, 23b which extend between the upper end and the lower end thereby creating a chamber 24; (ii) an upper closure 25 with an opening 26; and (iii) a lower closure 27 with a discharge port 28; the chamber having a plurality of plates 29a-f, each plate having a top surface 30, a bottom surface 31 and sides 32a-d; wherein each of said plates is positioned in said chamber with one side located higher in the chamber than its opposing side so that the top surface of said plate slopes towards the lower end of said container, and each of said plates is positioned in said chamber with a gap between the relatively higher side of each of said plates and said side wall and a gap between the relatively lower side of each of said plates and said side wall. A method of filling the container comprises feeding material into the opening so that the material falls through the gap between the relatively higher edge of each of the plates and the side wall.

Description

(71) Applicant(s):

Fjelldal Consulting & Engineering AS (Incorporated in Norway)

23A, Sluppenvegen, Trondheim 7037, Norway (72) Inventor(s):

Alf Kristian Fjelldal (74) Agent and/or Address for Service:

Marks & Clerk LLP

62/68 Hills Road, CAMBRIDGE, CB2 1LA, United Kingdom (51) INT CL:

B65D 88/26 (2006.01) (56) Documents Cited:

JP 2003237886 A SU 001479369 A1

JP S5767429 JP H11222291 (58) Field of Search:

INT CL B65D

Other: Online: EPODOC, WPI (54) Title of the Invention: Container

Abstract Title: Storage container with sloped plates (57) A storage container 20 particularly suitable for bulk materials comprises:

(i) an upper end 21 and a lower end 22 and side walls 23a, 23b which extend between the upper end and the lower end thereby creating a chamber 24;

(ii) an upper closure 25 with an opening 26; and (iii) a lower closure 27 with a discharge port 28;

the chamber having a plurality of plates 29a-f, each plate having a top surface 30, a bottom surface 31 and sides 32a-d;

wherein each of said plates is positioned in said chamber with one side located higher in the chamber than its opposing side so that the top surface of said plate slopes towards the lower end of said container, and each of said plates is positioned in said chamber with a gap between the relatively higher side of each of said plates and said side wall and a gap between the relatively lower side of each of said plates and said side wall.

A method of filling the container comprises feeding material into the opening so that the material falls through the gap between the relatively higher edge of each of the plates and the side wall.

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

1/8

06 18

Fig. 1 c

2/8

3/8

^Fi9-6

4/8

06 18

Fig.8c

Fig.8d

5/8

06 18

3 4

Fig.9a Fig.9b Fig.9c Fig.9d

2

4

Fig. 10c Fig.lOd

Fig.10a Fig.lOb

6/8

06 18

Fig.11a ^-28

28a

28b

Fig.11b

7/8

06 18

Fig.12

Fig.13b

Fig. 13a

Fig. 13c

8/8

06 18

Fig.13d Fig.13e Fig.13f

Fig.14

Container

INTRODUCTION

The present invention relates to a storage container, and in particular to a storage container for bulk materials comprising particles of different sizes. Advantageously the bulk material may be filled into, and discharged from, the storage container of the invention as a non-segregated mixture. The invention also relates to a method of filling a storage container of the invention and to a method of storing a bulk material, which comprises particles of a range of different sizes, homogeneously. Additionally the invention relates to a method of obtaining a homogeneous mixture of a bulk material from a storage container.

BACKGROUND

Many bulk materials are stored in storage containers such as silos until they are required. Storage containers are used in a number of different industries including agriculture where they are used to store grain and silage, aquaculture where they are used to store fish food, the energy sector where they are used to store coal, construction where they are used to store cement, sand, fuel ash as well as a number of chemical industries where they are used to store a wide range of materials such as aluminium oxide, limestone and plastic granulates. A significant number of these bulk materials comprise particles of a range of different particle sizes.

Conventional storage containers have a relatively simple structure. Typically they comprise an upper end and a lower end, and having sidewalls which extend between the upper end and the lower end to create a chamber. The upper end is closed by an upper closure which includes an opening for feeding material into the container and the lower end is closed by a lower closure which includes a discharge port for discharging material out of the container. Typically the lower closure is tapered so that the material slides towards a centrally located discharge port. The chamber is usually smooth to facilitate the discharge of material from the container. Thus in conventional containers, most of the support structure for the container is present on the exterior of the container. They are often, for example, supported in an external frame.

A number of problems are, however, encountered with conventional storage containers, particularly when they are used to store bulk materials comprising a range of different particle sizes. When bulk materials are filled into conventional storage containers, they are usually fed into an opening in the upper closure and drop therefrom into the container. If the container is empty, or close to empty, this means the material might drop over 50 m, and in some cases, up to 90 m. Such a drop can cause some materials to fragment which means that the material ultimately discharged from the container is different to the material which was fed in. For some materials this is a significant problem. If, for instance, the material is for use in a chemical process, the size of the particles determines their surface area and therefore can significantly impact on the reaction rate of any subsequent chemical reaction in which it is present.

Second, it is not always possible to fill conventional storage containers to their full capacity without compromising the integrity and/or quality of the stored bulk material. This is because the total weight, and therefore pressure, experienced by material present towards the bottom of the container is immense due to the height of the container. With a bulk material such as fish feed this causes significant problems. If a tall storage container is filled, the total weight of the fish food causes the food present towards the bottom of the container to exude oil. This significantly changes the composition of the food which is ultimately discharged from the container and also causes the fish food to become sticky or tacky and to stick to the interior of the container. It therefore becomes difficult to completely empty the storage container. When storing materials such as fish food it is therefore necessary to use smaller containers and/or to incompletely fill larger containers.

A third problem encountered with conventional storage containers is segregation. Segregation occurs whenever the bulk material to be stored in the container comprises particles of a range of different sizes. Segregation occurs during filling of the container as well as during discharge of material from the container. During filling the smallest particles present in the bulk material tend to accumulate in a column in the centre of the container and the largest particles tend to accumulate against the walls of the container. Between the column and the side walls there tends to exist a gradient of particles of increasing particle size. When material is subsequently discharged from the storage container, the mixture obtained is not the same as the bulk material which was fed into the container. Typically the column of smallest particle sizes will empty first creating a so-called rat hole followed by the next smallest particles and so on. This represents a significant problem since rarely would an entire storage container be emptied in a single operation and hence the overall mixture of bulk material obtained is different to that fed in and will be different from batch to batch obtained from the storage container.

The problem of segregation during filling and discharge has, to some extent, been overcome by providing storage containers with a means for stirring or mixing their contents. Typically stirrers or vibrators are provided, or alternatively a means to blow air into the mixture and agitate it are provided. Such mixing devices, however, increase the complexity and cost of containers and are prone to break down.

SUMMARY OF THE INVENTION

Viewed from a first aspect the present invention provides a storage container comprising:

(i) an upper end and a lower end, and having side walls which extend between the upper end and the lower end thereby creating a chamber;

(ii) an upper closure which closes the upper end of said container, said upper closure having an opening located therein; and (iii) a lower closure which closes the lower end of said container, said lower closure having a discharge port located therein;

the chamber having located therein a plurality of plates, each plate having a top surface, a bottom surface, and sides;

Viewed from a further aspect the present invention provides a method of filling a storage container as hereinbefore described with a material comprising: feeding a material into said opening in said upper enclosure so that said material falls through said gap between the relatively higher side of each of said plates and said side wall.

Viewed from a further aspect the present invention provides a method of storing a bulk material which comprises particles of a range of different sizes comprising: filling said bulk material into a storage container as hereinbefore described.

Viewed from a further aspect the present invention provides a method of obtaining a homogeneous mixture of a bulk material comprising:

discharging said bulk material from a storage container as hereinbefore described.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a storage container comprising:

(ii) an upper closure which closes the upper end of the container, the upper closure having an opening located therein; and (iii) a lower closure which closes the lower end of the container, the lower closure having a discharge port located therein;

the chamber having located therein a plurality of plates, each plate having a top surface, a bottom surface, and sides.

A preferred storage container of the invention is a silo. Preferred containers e.g. silos, have a chamber having a square, rectangular, hexagonal, circular, oval or obround cross section.

The positioning of the plates in the chamber of the container is critical. Each of the plates is positioned in the chamber so that two conditions are satisfied. First each plate is positioned so that one side is located relatively higher in the chamber than its opposing side so that the top surface of the plate slopes towards the lower end of the chamber. This ensures that during both filling and emptying material can slide down the plate surface towards the lower end of the chamber. Second each of the plates is positioned in the chamber with a gap between their relatively higher side and the side wall and with a gap between the relatively lower side and the side wall. This ensures that the container can be properly and completely filled and, most significantly, that during emptying material is discharged from each of the plates present in the container simultaneously. This is critically important as it means that materials comprising a range of different particle sizes may be discharged from the container without undergoing segregation during the discharge process.

In preferred containers of the present invention each of the plates slope towards the lower end of the chamber. In particularly preferred containers of the present invention each of the plates slope in the same direction towards the lower end of the chamber. Particularly preferably the plates are in a substantially parallel arrangement relative to each other. This means that during emptying stored material is discharged from each plate simultaneously. Thus during discharge, material flows down the top surface towards the gap between the relatively lower side of the plate and the side wall and empties into the gap.

Preferred containers of the present invention may comprise 3 to 40 plates, more preferably 5 to 25 plates and still more preferably 6 to 15 plates. Preferably the distance between adjacent plates is constant. The plates may be any shape, but preferably the plates are square, rectangular, circular, oval or obround. Particularly preferably each of the plates in the container is the same shape, e.g. square or rectangular.

In preferred containers of the present invention, each of the plates present therein is identical in size. The actual size of the plates depends on the size of the container and the material to be stored therein. Typically, however, each of the plates has a length of 20 m, more preferably 10 m and still more preferably 5 m. Typically each of the plates has a width of 20 m, more preferably 10 m and still more preferably 5 m. Typically each of the plates has a depth of 200 mm, more preferably 50 mm and still more preferably 20 mm.

The plates may be made of any material conventionally used in the manufacture of storage containers. For instance, the plates may be made of steel, aluminium, plastics, glass-reinforced plastics, wood or concrete.

In preferred containers of the present invention, each plate is centrally located within the chamber. Thus the gap between the relatively higher and relatively lower sides of the plates and the side walls is preferably constant. Preferably the gap between the relatively higher side of each of the plates and the side wall is at least 5% of the overall width of the chamber. Preferably the gap between the relatively higher side of each of the plates and the side wall is 5 to 15% of the overall width of the chamber and still more preferably 5 to 10 % of the overall width of the chamber. Preferably the gap between the relatively lower side of each of the plates and the side wall is at least 5% of the overall width of the chamber. Preferably the gap between the relatively lower side of each of the plates and the side wall is 5 to 15% of the overall width of the chamber and still more preferably 5 to 10 % of the overall width of the chamber.

In preferred containers of the present invention, the gap between the sides of each plate and the side walls extends around at least 50 % and more preferably at least 75 % of the perimeter of the side walls. In some containers the gap between the sides of each plate and the side walls extends around substantially the entirety of the perimeter of the side walls. For instance, in some containers only the corners of each plate may contact or abut the side walls of the container. In other containers, no part of each plate may contact or abut the sides walls of the container. The plates are preferably fixed to the side walls of the container. Any conventional fixing means may be used.

In preferred containers of the present invention the top surface of each of the plates slopes towards the lower end of the chamber at an angle of 15 to 75°, more preferably 25 to 45°, and still more preferably 30 to 40° to the plane through the edge formed by the top surface and the relatively higher side of the plate and which is perpendicular to the side walls. In further preferred containers of the present invention the top surface of each of the plates slopes towards the lower end of the chamber at the same angle to the plane through the edge formed by the top surface and the relatively higher side of the plate and which is perpendicular to the side walls.

In further preferred containers of the present invention the plates slope in at least two different directions towards the lower end of the chamber. Preferably at least one plate slopes towards a side wall of the container, which is opposite to the side wall that at least one other plate slope towards. The plates, therefore, preferably slope towards the lower end of the chamber, but towards at least two different side walls. The relatively higher sides of each of the plates is preferably located towards the centre to the chamber and away from the side wall. Preferably, a gap is present in between the relatively higher sides of the plates which slope in different directions towards the lower end of the chamber. Particularly preferably, the opening(s) in the upper closure is positioned so that it substantially overlies the gap present between the relatively higher sides of each of the plates which slope in different directions towards the lower end of the chamber.

Preferably, the plates are arranged in the chamber to form two or more columns of plates within the chamber. More preferably, each of the plates in a column slope in the same general direction. More preferably still, each plate in a column is equally spaced apart. Preferably, the relatively higher side of a plate is level in the chamber with the relatively higher side of a plate in an adjacent column. The relatively higher sides of plates in a column may alternatively not be level with plates in an adjacent column, and can therefore be staggered.

In preferred containers of the invention, the chamber has a circular, oval, obround, square, rectangular or hexagonal cross section. Containers having a circular, oval or obround cross sections are, however, preferred. Containers with circular cross sections are especially preferred.

In further preferred containers of the invention, the position of each of the plates in the chamber is adjustable. Preferably the spacing of the plates (i.e. the vertical distance between adjacent plates) is adjustable. Preferably the slope of the top surface of the plates is adjustable. In particularly preferred containers of the invention, both the spacing of the plates and the slope of the top surface of the plates is adjustable.

In preferred containers of the invention, the opening in the upper closure is configured to receive a feeding device. Optionally the opening can be provided with a removable lid. In this case, the lid is removed prior to the insertion of any feeding device. The opening may be any suitable size. Exemplary openings are 600 mm by 600 mm. The closure and opening may be any shape, for instance, the closure may be flat or curved and the opening may be circular, square or rectangular. The upper closure may have a single opening or multiple (e.g. 2, 3 or 4) openings. The opening may be located anywhere in the upper closure. Preferably, however, the opening(s) in the upper closure is positioned so that it substantially overlies the gap between the relatively higher side of each of the plates and the side wall. This facilitates the correct and complete filling of the container. When material is initially filled into the storage container, it drops through this gap between the relatively higher side of each of the plates and the side wall to the bottom of the container and fills the space underneath the lowermost plate in the container. As the space under the lowermost plate in the container begins to fill, however, a column of material begins to accumulate against the side wall adjacent to the relatively higher sides of the plates. Thus as the space underneath the lowermost plate in the container is filling, the material also starts to slide down the slope of the lowermost plate and fill the container through the opposing gap. Once the entire space underneath the lowermost plate is filled, the material starts to accumulate above the lowermost plate. The filling pattern then repeats itself until the space between the first plate and the second plate is filled. A very high filling level is readily achieved.

A significant advantage of the storage container of the present invention is that segregation of particles of different sizes occurs to a far lesser extent than in a conventional storage container. Thus a column of particles of the smallest particle size does not form in the container of the present invention and there is little, if any, accumulation of the largest particles towards the side walls of the container. This is achieved because the majority of the filling is achieved by the material sliding along the plates, or along material, already present on the plates, rather than by dropping directly into the container.

Another advantage of the present invention is that significant segregation of particles of different size does not occur during discharge of the material from the storage container. Thus the material obtained after discharging material from a storage container of the invention is substantially the same as the material that was initially fed into the container. This is achieved because material is discharged from all of the different plates present in the container simultaneously. When the discharge port is opened and material is discharged therefrom, material present in the storage container slides down the plates towards the relatively lower sides thereof. The storage container therefore empties from the side wall adjacent the relatively higher sides of the plates towards the side wall adjacent the relatively lower sides of the plates. Critically material is discharged from all of the plates at the same time. This is due to the slope of the plates and the gap between the plate sides and the side walls of the chamber. Only when very little material is left in the storage container does discharge occur from a single plate. Moreover a very high level of discharge is achieved.

A consequence of the fact that the container of the present invention can be both filled and emptied without causing significant segregation is that there is no need to incorporate any stirring apparatus into the container. Preferred containers of the invention do not comprise any stirring apparatus. This simplifies the design of the container and makes it more reliable.

In further preferred containers ofthe present invention the lower closure tapers towards the discharge point. This facilitates emptying of the container. The discharge port can be located anywhere in the lower enclosure. Preferably the discharge port is centrally located in the lower closure. The shape of the discharge port can be any shape, but preferably is square, rectangular or circular. The side walls, and closures, of the container of the invention may be made of any material conventionally used in the manufacture of storage containers. For instance, the side walls, and closures may be made of steel, aluminium, plastics, glass-reinforced plastics, wood or concrete.

The containers of the present invention may be a wide range of sizes depending on the material they are intended to store. The container may, for example, have a height of up to 100 m. Preferably the containers of the invention have a height of 80 m, more preferably 40 m and still more preferably 10 m. When the containers have a circular cross section, the containers preferably have a diameter of 20 m, more preferably 10 m and still more preferably 5 m. When the containers have a square cross section, the containers preferably have a length and width of 20 m, more preferably 10 m and still more preferably 5 m.

Preferred containers of the present invention have a volume of 50 000 m³, more preferably 1 000 m³and still more preferably 200 m³.

A preferred container of the present invention is a silo.

The containers of the present invention preferably contain a bulk material and particularly preferably a bulk material which is non-homogeneous in particle size. Representative examples of bulk materials include fish food, cement, aluminium oxide, wood chips, limestone or plastic granulates.

The present invention also relates to a method of filling a storage container as hereinbefore described with a material comprising: feeding a material into the opening in the upper enclosure so that the material falls through the gap between the relatively higher side of each of the plates and the side wall. In preferred methods of the invention, during filling, the material slides down the top surface of the plates towards the gap between the relatively lower side of each of the plates and the side wall. Preferred methods comprise filling the container to 90-100 % capacity and more preferably to 95-100 % capacity. This is straightforward as the design of the container of the present invention facilitates high filling levels.

The present invention also relates to a method of storing a bulk material which comprises particles of a range of different sizes comprising: filling the bulk material into a storage container as hereinbefore defined. In preferred storage methods the bulk material is present as a homogeneous mixture in the storage container.

The present invention also relates to a method of obtaining a homogeneous mixture of a bulk material comprising: discharging the bulk material from a storage container as hereinbefore defined.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1a is a schematic of a conventional storage container;

Figure 1b shows the same conventional storage container as Figure 1a and illustrates the problem of bridging;

Figure 1c shows the same conventional storage container as Figure 1a and illustrates the problem of segregation;

Figure 2a is a schematic of a storage container of the present invention;

Figure 2b shows a schematic of a plate 29a employed in the storage container of the present invention,

Figure 3a shows the same storage container as Figure 2 but viewed from above;

Figure 3b shows the same storage container as Figure 2 but viewed from above through dashed line A;

Figure 3c shows the same storage container as Figure 2 but viewed from underneath;

Figure 4 is a schematic of another storage container of the present invention;

Figure 5 is a schematic of another storage container of the present invention;

Figure 6 is a schematic of a part of storage container of the present invention showing only a single plate 37a;

Figure 7a is a schematic of another storage container of the present invention;

Figure 7b shows the same container as Figure 7a but viewed from above through dashed line A;

Figure 8a is a schematic of another storage container of the invention when viewed from above through a section wherein a plate is present;

Figure 8b is a schematic of another storage container of the invention when viewed from above through a cross section where a plate is present wherein the chamber is circular;

Figure 8c is a schematic of another storage container of the invention when viewed from above through a cross section where a plate is present wherein the gap between the edges of each of the plates and the side walls of the chamber extends all of the way around the perimeter of the side walls of the chamber;

Figure 8d is a schematic of another storage container of the invention when viewed from above through a cross section where a plate having an obround cross section is present, in a chamber having a circular cross section;

Figures 9a-9d are a schematic of the correct filling of a storage container of the present invention;

Figures 10a-10d are a schematic of the correct emptying of a storage container of the present invention;

Figure 11a is a schematic of another storage container of the present invention;

Figure 11 b is a schematic of another storage container of the present invention;

Figure 12 is a photograph showing segregation of a material of different particle size, following feeding of the material into a collection drum to model filling of a conventional storage container;

Figures 13a is a photograph of a storage container of the invention viewed from the side, wherein the container has been filled with material that is segregated by particle size;

Figure 13b is a photograph of the same storage container as Figure 12a but viewed from the front;

Figure 13c is a photograph of the same storage container as Figure 12a showing discharge of material from the storage container;

Figure 13d is a photograph of the same storage container as Figure 12a showing discharge of material from the storage container, but viewed from the front;

Figure 13e is a photograph of the same storage container as Figure 12a showing discharge of material from the storage container, but viewed from the front;

Figure 13f is a photograph of the same storage container as Figure 12a showing a latter stage of discharge of material from the storage container; and

Figure 14 is a photograph of material of variable particle size dispensed from the same storage container as Figure 12a.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1a shows a cross section of conventional storage container. The container comprises a chamber 1 bounded by a plurality of side walls 2a, 2b. The chamber has an upper end 3 which is closed by an upper closure 4. The upper closure 4 has an opening 5 to receive a feeder (not shown). Optionally the opening is provided with a lid (not shown). The opening is centrally located in closure 4. The chamber also has a lower end 6 which is closed by lower closure 7. The lower closure 7 tapers inwardly from the side walls. The lower closure provides downwardly sloping surfaces 8 in the chamber of the container. The downwardly sloping surfaces 8 are connected to a discharge port 9.

In operation bulk material, e.g. fish food, is filled into the storage container via a feeder which is placed into the opening 5 in the upper closure 4. From the feeder, the material falls, under gravity, into the container. If the material is fed into an empty container the material falls the entire length of the container which can cause fragmentation of the material. Generally the container fills from the bottom upwards, with newer material coming to rest on top of material already present in the container. The total weight on the material present towards the bottom of the container is huge and this can also cause break down of material. With certain materials, such as fish food, the heavy weight can also cause the material to exude some of their constituents, such as oil.

A further problem arises as a consequence of the immense weight of the stored material during emptying of the container. When stored material (shown by hashed lines) is required, the container is opened at discharge port 9 and material flows out of the container. It is not uncommon, however, for the flow of material to cease after only a relatively low volume of material is discharged. This is caused by the heavy load creating such a high pressure in the container that “bridging” occurs. This is depicted in Figure 1b. Bridging can only be avoided by reducing the amount of weight of material in the storage container and/or by reducing the rate of discharge from the container.

Segregation is another significant problem encountered with conventional storage containers. During filling of the material into the container, if the material is a mixture of particles having different particle sizes, segregation will occur. Thus the relatively larger particles will tend to accumulate towards the outside the container and the relatively smaller particles tend to accumulate in the centre of the container. This is shown in Figure 1c, wherein smaller particles 10 are present as a column in the centre of the container and increasingly larger particles 11 surround the cone. The largest particles 12 tend to be present towards the walls of the container.

Such segregation causes problems during emptying of the container and impacts on the quality of the material obtained. The column of relatively smaller particles 10 tends to flow out of the discharge port 9 more readily than the relatively larger particles. This is sometimes referred to as “ratholing”. As a result the particle mixture obtained by discharging stored material from the container tends to be different to the particle mixture that was fed in. This is the case throughout the discharge process. During the initial discharge, compared to the original mixture fed into the container, there is a disproportionate amount of smaller particles due to ratholing and during later discharge there is a corresponding lack of the smaller particles. This can obviously cause problems if the material is to be used for chemical processes.

Figure 2a shows a cross section of a storage container of the present invention. The container 20 comprises an upper end 21 and a lower end 22 and having side walls 23a, 23b, which extend between the upper end and lower end to create a chamber 24. The upper end 21 is closed by an upper closure 25. The upper closure 25 has an opening 26 to receive a feeder (not shown). The opening 26 is non-centrally located in the upper closure as discussed below in more detail. The lower end 22 is closed by a lower closure 27. The lower closure has a discharge port 28 located therein for discharging material from the container. The discharge port may be located centrally as shown in Figure 2a or non-centrally as shown in Figure 4.

The chamber 24 has located therein a plurality of, e.g. 6, plates 29a, 29b, 29c, 29d, 29e, 29f. Figure 2b shows a schematic of the plate 29a. The plate has a top surface 30, a bottom surface 31 and sides 32a-32d. Sides 32a and 32b are opposing sides as they are opposite each other. Sides 32c and 32d are similarly opposing sides. The shape of the plate 29a is square but it could be a different shape.

Each plate 29a-29f is positioned in the chamber with one side 32c located relatively higher in the chamber than its opposing relatively lower side 32d (the vertical space is indicated in Figure 2b by the arrow) so that the top surface of the plate slopes towards the lower end of the chamber. All of the plates 29a-29f slope in the same general direction. In Figure 2a the plates are generally parallel to each other, but nonparallel arrangements are all possible. Each plate 29a-29f is also positioned in the chamber with a gap 33 between the relatively higher side 32c and the side wall 23a and with a gap 34 between the relatively lower side 32d and the side wall 23b.

Figure 3a shows the same storage container as Figure 2 but viewed from above. The top of each of the side walls 23a, 23b, 23c and 23d can all be seen. The upper closure 25 closes the upper end of the chamber and comprises an opening 26a to receive a feeder. The opening in the upper end may alternatively be located as shown by openings 26b and 26c. The openings 26a-c are located towards the side wall 23a and overlies the gap 33 between the relatively higher side 31c and the side wall 23a. As will be described below in more detail, the location of the openings 26a-c above the gap 33 is important during filling of the container.

Figure 3b shows the same storage container as Figure 2a but viewed from above through dashed line A. As in Figure 3a, the top of each of the side walls 23a, 23b, 23c and 23d can all be seen. This Figure also shows the gap 33 between the relatively higher side 32c of plate 29b and side wall 23a as well as the gap 34 between the relatively lower side 32d of plate 29b and the side wall 23b. In the container shown in Figure 3b, the gaps 33 and 34 are the same size, but they could be different. The gap extends around 50% of the total perimeter of the side walls of the chamber.

Figure 3c shows the same storage container as Figure 2 but viewed from underneath. The bottom of each of the side walls 23a, 23b, 23c and 23d can all be seen. The lower closure 27 closes the lower end of the chamber and comprises a discharge port 28. The discharge port 28a is located centrally, but could alternatively be located non-centrally, as shown by dashed ports 28b, 28c, 28d, relative to the cross section of the chamber 24. The discharge port is conventional.

Figure 4 shows a cross section of another storage container of the present invention. The features of the container shown in Figure 4 that are the same as those in Figure 2 have the same reference sign as given in Figure 2. The main differences between the storage container shown in Figure 4 compared to the container shown in Figure 2 is in the number of plates,in the spacing between the plates and in the location of the discharge port. In Figure 4, there are only four plates 35a, 35b, 35c and 35d. The vertical spacing between adjacent plates 35 in the container of Figure 4 (e.g. between plates 35a and 35b as shown by the arrow) is greater than the vertical spacing between the adjacent plates 29 in the container in Figure 2. In both containers the spacing is constant, although this is not necessarily the case. The spacing between plates 35 in the container of Figure 4 is larger because the container is designed for storage of a different material. The spacing between plates can be designed based on the weight of the storage material, its tendency to fragment and on its tendency to exude its constituents under pressure. For instance, containers for storage of more “sensitive” materials, e.g. those with a lower ability to withstand pressure and/or greater tendency to exude constituents, usually have a smaller spacing between adjacent plates than container for more “robust” materials. The smaller spacing between adjacent plates reduces the total weight experienced by material present in the container and in particular the weight experienced by material present at the lower end of the container. The overall lower pressure on the material in the container also reduces its tendency to stick to the walls of the container and improve its flow out of the container during discharge. The discharge port 28 is non-centrally located in the lower closure of the container.

Figure 5 shows a cross section of another storage container of the present invention. The features of the container shown in Figure 5 that are the same as those in Figure 2 have the same reference sign as given in Figure 2. The main differences between the storage containers shown in Figures 2 and 5 is in the number of plates and the slope of the top surface of the plates towards the lower end of the chamber. In Figure 5 there are only three plates 36a, 36b, 36c. As in Figure 2, each plate 36a-36c is positioned in the chamber with one side located relatively higher in the chamber than its opposing relatively lower side so that the top surface of the plate slopes towards the lower end of the chamber. In the storage container of Figure 5, however, the slope of each plate towards the lower end of the chamber is different and the plates 36a-36c are non-parallel. The plate 36a nearest the upper end of the chamber has a shallower slope than the central plate 36b which in turn has a shallower slope that the plate 36c which is nearest the lower end of the chamber.

Figure 6 is a schematic of a part of storage container of the present invention showing only a single plate 37 with top surface 30 and sides 37a-37d. As in Figures 2 and 5, plate 37a is positioned in the chamber with one side located relatively higher in the chamber than its opposing relatively lower side so that the top surface of the plate slopes towards the lower end of the chamber. The angle of the slope may be defined relative to the plane which runs parallel to the upper edge formed by the top surface 30 and side 32c and which is perpendicular to side walls 23a and 23b, as shown by a in Figure 6a. In Figure 6a, a is about 30°, but a could be any angle between 15° and 75°. Thus referring back to Figure 5 discussed above, plate 36a might be at an angle a of 20°, plate 36b at an angle a of 30° and plate 36c at an angle a of 45°.

Figure 7a is a schematic of another storage container of the present invention. Figure 7b shows the same container but viewed from above through dashed line A. In the container shown in Figures 7a and 7b, each of the plates 38a-38c are shorter in length compared to the plates 29a-29f in Figure 2. The plates are all of equal length, but plates of different lengths could be employed. Additionally the plates are all in a central position in the chamber, i.e. the gap between the sides of the plates 38a-38c and each of side walls 23a and 23b is the same. The plates may, however, be noncentrally located in the chamber with the gap between the side of the plate and one side wall larger than the gap between the opposing side of the plate and another side wall.

The use of plates 38a-38c of shorter length means that the gap between the sides of the plate 38a-38c and each of the side walls 23a, 23b is larger. This is best seen in Figure 7b wherein the gap is represented by the hatched areas. The total width of the gap is about 10% (5% on each side) of the overall width of the chamber.

Figure 8a is a schematic of another storage container of the invention when viewed from above through a section wherein a plate is present. In the container shown in Figure 8a, one side of the plate 39 abuts a single side wall of the chamber and there is gap between the other sides of the plate 39 and the three other side walls, 23a, 23b and 23c. The gap extends around 75% of the total perimeter of the side walls of the chamber. All of the gaps are the same size. The plate 39 is fixed to the side walls by fixtures 40a and 40b. Any number of fixtures may be used.

In the container shown in Figure 8b, the cross section of the chamber is circular, rather than square or rectangular. In this container only the corners of the plate 39 contact the side walls. The plate is fixed to the side walls at the corners by fixtures 40a, 40b, 40c and 40d. The gap between the sides of the plate 39 and the side walls therefore extends substantially all of the way around the perimeter of the side walls of the chamber. In the container shown in Figure 8c, none of the plate sides or corners abut the side walls of the chamber. There is a gap between the side of the plate 39 and all of the side walls 23a-23d of the chamber. The gap therefore extends all of the way around the perimeter of the side walls of the chamber. As in the container shown in Figure 8b, the cross section of the chamber is circular. The plate 39 is fixed to the side walls by fixtures 40a, 40b, 40c, 40d.

In the container shown in Figure 8c, two opposite sides of the obround shaped plate 41 abut the side walls of the chamber and there is a gap between the other sides of the plate 41 and the side walls. The gap is of variable size. As in the containers shown in Figures 8b and 8c, the cross section of the chamber is circular.

Figures 9a-9d are a schematic of the correct filling of a storage container of the present invention. The opening in the upper enclosure is configured to receive a chute which delivers material into the container. As shown in Figure 3a, the opening in the upper enclosure is positioned so that it substantially overlies the gap between the relatively higher side of each of the plates and the side wall. Thus when material is delivered into the storage container, it drops through the gap to the bottom of the container. As shown in Figure 9a, initially the material drops to the bottom of the container and underneath the lowermost plate in the container. As the space under the lowermost plate in the container begins to fill, however, a column of material begins to accumulate against the side wall adjacent to the relatively higher sides of the plates. Thus as the space underneath the lowermost plate in the container is filling, the material also starts to slide down the slope of the lowermost plate and fill the container through the opposing gap. Once the entire space underneath the lowermost plate is filled, the material starts to accumulate above the lowermost plate. As shown in Figures 9b and 9c, the filling pattern mirrors the plate arrangement. This is due to the fact that the material slides down the plates in the filling process. A very high filling level is achieved (Figure 9d).

It can also be seen that the total weight resting on any material present in the storage container of the present invention is significantly less than in a conventional storage container. Significantly the total weight and pressure on the material present in the bottom of the storage container is only a fraction of the weight and pressure on material present at the bottom of a conventional storage container. This means that products such as fish food having a tendency to exude their constituents can be stored in much larger containers without the risk of changing their composition and compromising their quality. Similarly materials with a tendency to fragment or crush under pressure can be stored in the storage containers of the present invention without a risk of reducing the quality or integrity of the material. Reducing the pressure within the storage container also avoids the problem of bridging.

Figures 10a-10d are schematics of the emptying or discharging of a storage container of the present invention. A significant advantage of the present invention is that significant segregation of particles of different size does not occur during discharge of the material from the storage container. Thus the material obtained after discharging material from a storage container of the invention is substantially the same as the material that was initially fed into the container. This is achieved because, as illustrated in Figure 10, material is discharged from all of the different plates present in the container simultaneously. As shown in Figure 10a, when the discharge port is opened and material is discharged therefrom, material present in the storage container slides down the plates towards the relatively lower sides thereof. The storage container therefore empties from the side wall adjacent the relatively higher sides of the plates towards the side wall adjacent the relatively lower sides of the plates. As is clear from Figures 10a and 10b, material is discharged from all of the plates at the same time. This is due to the slope of the plates and the gap between the plate sides and the side walls of the chamber. Only when very little material is left in the storage container does discharge occur from a single plate (see Figure 10c). A very high level of discharge is achieved (Figure 10d).

Figure 11a is a schematic showing a cross section of another storage container of the present invention. The chamber 24 has located therein a plurality of, e.g. 6, plates 42a, 42b, 42c, 42d, 42e, 43f. Each plate 42a-42f is positioned in the chamber with one side located relatively higher in the chamber than its opposing relatively lower side so that the top surface of the plate slopes towards the lower end of the chamber. Plates 42a-42c slope in the same general direction i.e. towards the lower end of the chamber and towards side wall 23b, and plates 42d-f slope in the same general direction i.e. towards the lower end of the chamber and towards side wall 23a.

Each plate 42a-42c is positioned in the chamber with a gap 33 between the relatively higher side 32c and the side wall 23a and with a gap 34 between the relatively lower side 32d and the side wall 23b. Each plate 42d-42f is positioned in the chamber with a gap 43 between the relatively higher side 32c and the side wall 23b and with a gap 44 between the relatively lower side 32d and the side wall 23a. Each of plates 42a-c, which slope in the same general direction towards the lower end of the chamber are arranged substantially above one another to form a first column of plates. Each of plates 42d-f which slope in the same general direction towards the lower end of the container, but in a different direction to plates 42a-c, are arranged substantially above one another to form a second column of plates. The relatively higher sides of the plates in each column are located towards the centre of the chamber and away from the side wall. A gap 45 is present in between the relatively higher sides 32c of each of the plates in adjacent columns. The opening 26 in the upper closure is located above the gap 45 between the two columns. Alternatively the opening may overlie the gap 45.

The relatively higher side 32c of each plate 42a-c in the first column is arranged to be level in the chamber with the higher side 32c of each plate 42d-f in the second column. Alternatively, the relatively higher side 32c of each plate 42a-c in the first column may be arranged to not be level with the relatively higher side 32c of each plate 42d-f in the second column i.e. the plates may be staggered.

The discharge port 28 is located centrally in the lower closure as shown in Figure 11a. Alternatively the discharge port may be located non-centrally. As shown in Figure 11b, there are optionally two discharge ports 28a and 28b. Discharge port 28a is located substantially below the first column formed by plates 42a-c, and discharge port 28b is located substantially below the second column formed by plates 42d-f.

EXAMPLES

Example 1 - Segregation of a material of differing particle size

Segregation of material comprising variable particle sizes was demonstrated using gravel. Gravel with a particle size of between 0 mm and 4 mm was fed into a collection drum at a height of 1 metre above the base of the collection drum. Visual inspection of the gravel following dispensation revealed accumulation of the largest gravel particles towards the side walls of the drum, and accumulation of the smallest gravel particles in a column in the centre of the drum. Further visual inspection revealed a gradient of increasing particle size from the centre of the gravel towards the sides of the drum (Figure 12). This models the filling of a conventional storage container.

Example 2 - Discharging from a storage container of the invention

As previously described, a material may segregate into different particle sizes when a storage container is filled. As a result, the mixture of particle sizes is not homogeneous between different batches of material discharged from the container.

To demonstrate a storage container of the present invention, a cubic storage container comprising four parallel square plates, centrally located in the container chamber and sloping towards the lower closure, was used. The opening of the upper closure was configured to overlie the gap formed by the relatively higher side of each plate and the side wall, and the discharge port was configured to be centrally located in the lower closure.

To aid visual inspection of different particle sizes in a material discharged from the container, beige coloured sand (particle size 1 mm) was used in admixture with grey gravel (particle size 0-4 mm).

The storage container was filled with alternating layers of sand and gravel. The sand and gravel layers provided visually observable segregation of different particle sizes within the storage container. Furthermore, the sand and gravel layers enabled evaluation of the discharge from each individual plate during discharge from the storage container.

The storage container was filled by:

(i) Feeding sand through the opening in the upper closure, allowing the sand to fall directly to the bottom of the container and continuing to add sand until approximately 40-60% of the space underneath the lowermost plate was filled.

(ii) Feeding gravel through the upper closure opening until the space defined by the sand from step (i) and the underneath of the lowermost plate is filled.

Two well-defined layers differing in particle size, a gravel layer on top of a layer of a sand layer, were therefore formed. Steps (i)-(ii) were repeated for the area above the lowermost plate and the underneath of the plate above, and repeated thereafter until the storage container was filled (Figure 13a-13b).

The filling of the container mirrored the arrangement of the plates therein. Material fed through the opening, accumulated in a column against the side wall adjacent to the relatively higher side of the plates. Once the area underneath a plate was filled, the material began to slide from the column of accumulating material, down the upper face of said plate, thereby beginning to fill the area above said plate. The layers of sand were observed to have a smaller angle of repose than the angle of repose defined by the slope of each plate.

Opening of the discharge port in the lower closure caused initial discharge of material from the gap formed by the relatively higher side of each plate and the side wall (Figure 13c). This material discharges most readily due to less pressure.

Once material stored in the gap formed by the relatively higher side of each plate and the side wall had descended to the bottom of the storage container, discharge of the sand and gravel continued through the gap formed by the relatively lower side of each plate and the side wall. Visual inspection of the sand and gravel layers revealed that material on the uppermost plates was simultaneously discharged with material on each of the lower plates (Figure 13d-13f). The simultaneous discharge of material from each plate resulted in efficient mixing of the sand and gravel during discharge.

Example 3 - Discharge and reduced segregation

The sand and gravel discharged in Example 2 was collected in a collection drum at regular intervals during discharge. Visual inspection of the collected mixture revealed the sand and gravel was well mixed, and that different particle sizes were uniformly distributed throughout the collection drum (Figure 14). Large gravel particles were observed across the mixture surface, including the centre of the drum, and did not preferentially accumulate towards the side walls of the drum. Furthermore, smaller sand particles were observed across the mixture surface, including towards the side walls of the drum, and did not preferentially accumulate in a column in the centre of the drum. The collected mixture therefore did not therefore show segregation of different particle sizes.

Claims

CLAIMS:

1. A storage container comprising:

2. A container as claimed in claim 1, wherein each of said plates slope towards the lower end of said chamber.

3. A container as claimed in claim 1 or 2, comprising 3 to 40 plates.

4. A container as claimed in any one of claims 1 to 3, wherein each of said plates is square or rectangular.

5. A container as claimed in any one of claims 1 to 4, wherein each of said plates is identical in size.

6. A container as claimed in any one of claims 1 to 5, wherein the distance between adjacent plates is constant.

7. A container as claimed in any one of claims 1 to 6, wherein the gap between the relatively higher side of each of said plates and the side wall is at least 5% of the overall width of said chamber.

8. A container as claimed in any one of claims 1 to 7, wherein the gap between the relatively lower side of each of said plates and the side wall is at least 5% of the overall width of said chamber.

9. A container as claimed in any one of claims 1 to 8, wherein the gap between the relatively higher and relatively lower sides of each of said plates and the side walls is constant.

10. A container as claimed in any one of claims 1 to 9, wherein the gap between the sides of each plate and the side walls extends around at least 50 % of the perimeter of said side walls.

11. A container as claimed in any one of claims 1 to 10, wherein the gap between the sides of each plate and the side walls extends around substantially the entirety of the perimeter of said side walls.

12. A container as claimed in any one of claims 1 to 11, wherein the top surface of each of said plates slopes towards the lower end of said chamber at an angle of 15 to 75° to the plane through the edge formed by said top surface and the relatively higher side of said plate and which is perpendicular to the side walls.

13. A container as claimed in any one of claims 1 to 12, wherein the top surface of each of said plates slopes towards the lower end of said chamber at the same angle to the plane through the edge formed by said top surface and the relatively higher side of said plate and which is perpendicular to the side walls.

14. A container as claimed in any one of claims 1 to 13, wherein each of said plates slope in the same direction towards the lower end of said chamber.

15. A container as claimed in any one of claims 1 to 14, wherein said plates are in a substantially parallel arrangement relative to each other.

16. A container as claimed in any one of claims 1 to 15, wherein each plate is centrally located within said chamber.

17. A container as claimed in any one of claims 1 to 13, wherein said plates slope in at least two different directions towards the lower end of said chamber.

18. A container as claimed in claim 17, wherein at least one plate slopes towards a side wall of the container which is opposite to a side wall that at least one other plate slopes towards.

19. A container as claimed in claim 18, wherein a gap is present in between the relatively higher sides of said plates which slope in different directions.

20. A container as claimed in claim 19, wherein each of said plates are arranged in the container to form two or more columns of plates within the chamber.

21. A container as claimed in claim 20, wherein each of said plates in a column slope in the same general direction.

22. A container as claimed in any one of claims 1 to 21, wherein said opening in said upper closure is positioned so that it substantially overlies the gap between the relatively higher side of each of said plates and said side wall.

23. A container as claimed in any one of claims 19 to 22, wherein said opening in said upper closure is positioned so that it substantially overlies the gap formed between the relatively higher sides of each of said plates which slope in different directions.

24. A container as claimed in any one of claims 1 to 23, wherein said opening in said upper closure is configured to receive a feeding device.

25. A container as claimed in any one of claims 1 to 24, wherein said chamber has a circular cross section.

26. A container as claimed in any one of claims 1 to 25, wherein the position of each of said plates in said chamber is adjustable.

27. A container as claimed in any one of claims 1 to 26, wherein said lower closure tapers towards said discharge point.

28. A container as claimed in any one of claims 1 to 27, wherein said discharge port is centrally located in said lower closure.

29. A container as claimed in any one of claims 1 to 28, wherein said container does not comprise any stirring apparatus.

30. A container as claimed in any one of claims 1 to 29 which is a silo.

31. A container as claimed in any one of claims 1 to 30, wherein said container contains a bulk material.

32. A container as claimed in claim 31, wherein said bulk material is nonhomogeneous in particle size.

33. A method of filling a storage container as claimed in any one of claims 1 to 32, with a material comprising:

feeding a material into said opening in said upper enclosure so that said material falls through said gap between the relatively higher edge of each of said plates and said side wall.

34. A method as claimed in claim 33, wherein during filling said material slides down the top surface of said plates towards the gap between the relatively lower edge of each of said plates and said side wall.

35. A method of storing a bulk material which comprises particles of a range of different sizes comprising:

filling said bulk material into a storage container as defined in any one of claims 1 to 32.

36. A method as claimed in claim 35, wherein said bulk material is present as a homogeneous mixture in said storage container.

37. A method of obtaining a homogeneous mixture of a bulk material comprising:

5 discharging said bulk material from a storage container as defined in any one of claims 1 to 32.

Intellectual

Property

Office

Application No: Claims searched: