EP1544132A2

EP1544132A2 - Container with emptying means, in particular for fuel pellets

Info

Publication number: EP1544132A2
Application number: EP04106179A
Authority: EP
Inventors: Dennis Karlsson
Original assignee: Denson-Produkter AB
Current assignee: Denson-Produkter AB
Priority date: 2003-12-01
Filing date: 2004-11-30
Publication date: 2005-06-22
Also published as: SE525237C2; SE0303216L; EP1544132A8; SE0303216D0; EP1544132A3

Abstract

In many pellet stores, like in the invention, the container is emptied using a feed screw from an area (M) at the bottom of the container. A pit then forms and the pellets along the walls will be left. This has previously been solved using a fixed inclined bottom at the cost of a bulky container. This has previously also been solved by a slantable bottom. All such solutions seem to have a cloth or bag, and if they have a feed screw, it is a bottom screw (a horizontal screw collecting pellets along the entire length of the container). The invention, however, enables a compact container entirely made of plywood (no cloth), provided with a slantable bottom. The invention also enables emptying by means of an inclined screw. The invention comprises a container, a main sheet (1) articulated to a side sheet (2), a shaft (3) and couplings (4) between the main sheet and the shaft. The angling of the main sheet makes the pellets fall down, and the side sheet prevents the pellets from falling down under the main sheet.

Description

BACKGROUND OF THE INVENTION - TECHNICAL FIELD

The invention is a container with an emptying device for storing and emptying of flowing, granular dry products such as pellets. The invention is particularly intended for use as a prefabricated container (L) for fuel pellets (P) and can be built in situ in restricted spaces such as boiler rooms (R) or the like (see Fig. 1a). In an intended application, the invention belongs to the category pellet stores.

BACKGROUND OF THE INVENTION - PROBLEMS SOLVED BY THE INVENTION

One problem involves minimising the size of the store. A pellet store in its context is illustrated in Fig. 1a: pellets (P) are fed by means of a screw (S) from the container (L) to the burner (B). As the container is being emptied, a pit forms around the area (M) where the screw intake is positioned. If the container is in the shape of a box like in the Figure - to take up as little space as possible in the room (R) - there will finally be pellets only along the edges and in the corners of the container and there will no pellets be left that the screw can feed. To make the pellets instead automatically collect in the feeding area (M), the simple pellet stores are built with an inclined bottom like a funnel with the feeding area adjacent to the spout. One half of such a store is shown in two variants in Figs 1b, 1c. An inclined plane having the width (y) and the angle of inclination (b) is positioned along one of the walls. An inclined screw (i.e. the type shown in Fig. 1a) is best suited for a store with a small width (y) according to Fig. 1b, since the pellets are collected from a small area (M) at the feed opening of the screw. For the sake of volume, (x), half the length of the transverse wall of the container, must then be great. On the other hand, for a bottom screw which is positioned horizontally along the bottom and has a plurality of feed openings, i.e. a plurality of feed points (M), the length (x) can be small according to Fig. 1c. An advantage of a short transverse wall, i.e. a small (x), is that the useless volume under the inclined plane will be relatively small. In order to further manage volume losses, stores with a slantable bottom have been developed (see the next paragraph).
A further problem involves easy and reliable emptying. Regarding the slantable bottom, the weight of the pellets is a particularly important parameter - both with regard to the mechanical construction and with regard to the fact that angling occurs by manual power. The store should hold at least 5 cubic meters since this is the smallest volume to be delivered in bulk (by a lorry blow-feeding pellets through a hose). This corresponds to approx. 3 tonnes. Also in this case, for the same reason as in the paragraph above, it is thus advantageous to have a bottom screw since the length (x) can be made small, which means that the weight being lifted by the slantable bottom will be correspondingly small. However, bottom screws are generally more expensive than inclined screws. An inclined screw may even be better since, in general, it cannot jam due to pellets getting stuck between the screw and the tube, which is a known problem of bottom screws.
What is particularly achieved by the invention will be described after the presentation of prior-art technique by known literature.

BACKGROUND OF THE INVENTION - PRIOR ART

Four main types of container with a slantable bottom for emptying of flowing products are illustrated in Fig. 2: the bottom is slanted by raising a cloth on the sides, by raising a sheet, by gathering the waist of a bag together, or by injecting air under a cloth (or into a bag).
The device disclosed in US Patent 4,541,765 has a winch arranged on the outside of the container (essentially according to Fig. 2a). The device of DE 1 531 920 works according to the same principle, but the winch is replaced by weights. The weights are suspended freely on the outside of the container and thus raise the cloth. Patent Specification US 2,829,803 contains an example of a device which essentially works according to Fig. 2b. In particular each lifting jack (103) for inclining the associated bottom sheet (102') is positioned under the container. The function of the product "Pellistore" is based on a bag (102) being pulled together essentially as shown in Fig. 2c, as far as we understand. Finally, FR Patent 2,512,790 discloses a device according to Fig. 2d, where the bottom sheet (102') can be inclined by means of compressed air (103).
It should be noted that the mechanism for angling the bottom is positioned outside the container in all containers except "Pellistore". The product "Pellistore" has a bottom screw (basically according to Fig. 1c). A reason for choosing a bottom screw seems to be the reduction of the strain on the cloth and its seams: the pellets are raised by the actual cloth, and the amount of pellets that must be raised will be considerably smaller if the store is built according to the principle in Fig. 1c.

FIGURES - DESCRIPTION

Fig. 1...Field of Application
Fig. 2...Prior Art
Fig. 3...Embodiments
Fig. 4...Components of the Emptying Device

FIGURES -DESIGNATIONS OF COMPONENTS

P...Pellets
L...Container
R...Room (boiler room or some other room)
B...Burner
S...Screw (for screw feeding of pellets or the like)
M...Area at the feed intake of the screw (area from which the container is emptied of its contents; feeding area; emptying area)
101...Joint
102...Cloth (for instance part of bag)
102'...Sheet
103...Power means
201...Filler pipe
202...Venting pipe
203...Connecting hole for feed screw
1...Main sheet (plywood or some other board)
2...Side sheet (plywood or some other board)
3...Coupling (for instance wire or chain)
4...Shaft
5...Joint between (1) and bottom sheet
6...Joint between (1) and (2)
7...Body of the container (also including the joists that work as strips)
8...Walls of the container (including roof and bottom)
9...Blocking device
31...Shaft mounting
32...Shaft nut
32'...Sleeve (for shaft nut)
33...Rod (for rotating the shaft)
41...Reinforcement of sheet (possibly combined with attachment for coupling)
42...Attachment of coupling to shaft
61...Angle bar or some other means to prevent (1) from falling flat on (2)
71...Joist
72...Strip
73...Strip
81...Bottom
82...Longitudinal wall (along inclined plane)
83...Transverse wall (transversely to inclined plane)
84...Roof
91...Ratchet
92...Catch
93...Protective cover

FIGURES - DIMENSIONS

a...Angle of repose
b...Angle of inclination of inclined plane
x...Length (horizontally, transversely to the inclined plane)
y...Length (horizontally, along the inclined plane)
h...Height

DESCRIPTION OF THE INVENTION - OBJECTS ACHIEVED BY THE INVENTION

What is to be particularly achieved by the invention in view of prior art is the following.
First, a store, simple in construction, is obtained, which can be emptied well using an inclined screw (no horizontal screw required).
Second, a particularly compact container is obtained, since the mechanism (for angling the bottom of the container) can be placed inside the container (in contrast to the mechanisms that are shown in Figs 2a, 2b). The mechanism can also be made quite manual: a compressed air apparatus as shown in Fig. 2c or another power source than manual power is not required.
Third, the holes for filling (201), venting (202) and screw feeding (203) can easily be placed where it suits best in every room - the holes can be placed on any side and do not require particular expert knowledge, special tools or special sets of connection. As far as we understand, such individual adaptation is easier to perform, compared with a store whose emptying mechanism uses a cloth like in Fig. 2c.
Fourth, a particularly simple mechanism is obtained for angling the bottom. It is easy to understand its function and repair is also easy, with standard components such as wires, mountings and pipes from the next hardware shop.
Finally, fifth, a tight container is obtained (in spite of the simple design of the emptying device) - as tight as an all-welded container or a common plywood store with no emptying device. This is to be contrasted with containers consisting of a bag, like in Fig. 2c, which are more difficult to get tight, for example because their seams are weakened, resulting in pellet dust leaking out.

DESCRIPTION OF THE INVENTION - EMBODIMENTS

One embodiment is shown in Fig. 3. The container with the roof removed and part of the walls cut away is shown in Fig. 3a. The emptying device is shown separately in Fig. 3b.
[Container] The container (see Fig. 3a) is limited by sheets of plywood consisting of a bottom (81), two transverse walls (82), two longitudinal walls (83) and a roof (84). These sheets are mounted on a body consisting of five U-shaped frames made of joists (71). Strips (72, 73) help to seal the container.
[Emptying Device] The emptying device (separately drawn in Fig. 3b) is divided into two active parts, each part comprising, inter alia, one sheet of plywood (1), another sheet of plywood (2), a shaft (3) and two wires (4). The sheet (1) - referred to as "main sheet" - abuts against, and is articulated to, blocks (5) fixed to the bottom sheet (81). The main sheet (1) is inclined by wires (4) being wound onto a shaft (3). The sheet (2) - referred to as "side sheet" - is articulated by a joint (6) to the main sheet (1). The side sheet (2) is pressed against the associated transverse wall (82) by its own weight and by the pellets. Angle bars (61) prevent the side sheet from falling flat on the main sheet when the container is empty.
[Shafts] The shafts (3) are rotatable in the support bearings (31). A support bearing may, like in this case, consist of a short pipe welded to a plate which can be screwed to the joists (71). A simpler solution is support bearings in the form of holes through the joists with some kind of plastic bushing or the like in the holes. It has been found that, for instance, joists that are only 40 mm thick will work.
[Blocking Device] A blocking device is indicated by the symbol (9). In this example it consists of a ratchet (91) fixed to the shaft (3), a catch (92) fixed to the outside of the support bearing (31) or on the outside of the joist (71), and a cover (93) that covers the ratchet.
[Wires] Only one wire is required for each main sheet (although a plurality of wires may, of course, be used). A single wire may extend in the form of a "U", down to the main sheet and under the same, along a flat bar or the like (41) that reinforces the sheet, and then up again.
[Use] The device is used in the following way. The rod (33) has a sleeve (32') which is fastened over one of the shaft nuts (32). As the rod (33) is then being rotated, the wires are wound onto the shaft (3), resulting in the main sheet (1) being raised at an angle. The side sheet (2) is carried along, scraping over the transverse wall (82). The main sheet can be gradually slanted up to a certain maximum position. If the rod (33) is rotated further, the main sheet can be lifted from the bottom. This facilitates removal of pellet dust collected under the sheets (1, 2). Depending on the design, the joint device (5) may need to be attached to the main sheet as well (and not only attached to the bottom like in the embodiment). To be able to lift the main sheet from the bottom in such a case, the joint device may be provided with an opening lock of some kind, such as lockable wires or chains or other prior-art devices.
[Connections] Holes are made in the sheets of plywood for supplying pellets, for ventilation and for feeding pellets to the screw, for instance in the positions designated (201, 202, 203) in Fig. 1. The holes can be positioned on any side of the container including the roof. The container may also be provided with a manhole cover for access (cleaning, manual redistribution of the very last amount of pellets, and repair). The container may also suitably be provided with a window for inspection of the pellet level. The window can be positioned in the manhole cover for instance.

DESCRIPTION OF THE INVENTION - GENERAL DESCRIPTION

Below follows a general description of the invention. First the emptying device and how it cooperates with the container will be described in general, mainly supported by the illustrations in Fig. 4. Then follows a general description of the container. Finally, a summary of the invention will be given.
The emptying device comprises at least one active unit, shown in three variants in Fig. 4a, Fig. 4b and Fig. 4c. Preferably two active units are included, independent of each other.
[Active Unit] An active unit comprises two sheets that are articulated to each other: a main sheet (1) and a side sheet (2). It also comprises one or more couplings (4), preferably wires or chains, that are to be wound onto a shaft (3). The couplings are attached to the main sheet (1) adjacent to the joint (6) between the sheets (1) and (2). It is to be noted that the main sheet need not be in one piece (like in Figs 4a, 4c) but may also be articulated in two (like in Fig. 4b) or more units. It is also to be noted that the main sheet, except being articulated to the side sheet, can also be movable along the same like in Fig. 4c.
[Main Sheet] The function of the main sheet is, of course, understood to force the heap of pellets (P) to be inclined more than the angle of repose (a), which then results in the heap becoming unstable and pellets falling down to the feeding area (M) until the angle of repose has been taken once more.
[Side Sheet] The function of the side sheet is less obvious. The function of the side sheet is to prevent pellets from entering under the main sheet. If there is no side sheet, a gap forms adjacent to the wall (82) through which pellets will fall down on the bottom (81) under the main sheet. In fact, it would be possible to solve this problem by pulling the rear edge of the main sheet up along the wall (82), but this would give the disadvantage of reducing the possible emptying degree since the front edge of the main sheet is pulled away, along the bottom (81), from the feeding area (M). The existence of a side sheet, independently of whether it is articulated to the main sheet like in Figs 4a, 4b or like in Fig. 4c, eliminates these problems and does so in a particularly simple way.
[Location of the shaft] The position of the shaft is to be noticed. In the Figures it is positioned so that the coupling (that shown in each Figure), except angling the main sheet, first pulls the main sheet (1) towards the feeding area (M) and the joint (5). Such a pulling force is available all the time up to a point where the inclination (b) of the sheet has exceeded the angle of repose (a). If the inclination is increased further, the coupling finally is moved to a vertical position. The sheets (1, 2) can be lifted from the bottom if the main sheet is loose or is made to come loose, adjacent to the joint (5). The shaft need not be placed in the position just described, but the two effects as mentioned are achieved if it is placed in that position.
As regards the support of the shaft, the driving of the shaft and a safety lock, the following may especially be noted. The shaft is supported by some kind of bearings - two examples have been described, but exactly how this is done is not critical to the function of the invention. The shaft can be rotated by manual power using some kind of rod extending radially from the shaft (for instance like the rod (33) in Fig. 3), but the rotation of the shaft can, of course, also be driven in some other way. The shaft can be provided with some kind of blocking mechanism which locks the shaft when the power rotating the shaft ceases. One example has been given (see (9) in Fig. 3), but other prior-art techniques can also be employed.
[Container] The characteristic features of the container are as follows. It is basically necessary for the two walls (83) to be parallel and flat in order to seal against the edges of the sheets (1, 2). In the embodiment, the walls (83) have been referred to as longitudinal walls, but here they are more generally called "transverse walls" to indicate that they are perpendicular to the sheets (1, 2), and that (83) in general need not necessarily be longer than the walls (82). In the embodiments according to Figs 4a, 4b, but not in Fig. 4c, also the "longitudinal walls" (82) must be flat to seal against the side sheets (2). The fact that the walls are "longitudinal" refers to their positioning along the inclined plane which consists of the sheets (1, 2). An example of how the just described seal between the walls and the sheets can easily be performed in a lasting manner is illustrated in Fig. 3. As to the rest, the following may also be noted. In the example sheets of plywood were mentioned, but of course other sheets may also be used. It is to be particularly noted that in the example the sheets cover the body on the inside, thus forming a gap both under the container and outside each transverse wall. This has, for instance, the advantage of ensuring a ventilating function between the floor of the room and the container and between the walls of the room and the container, which prevents diffusion of moisture (or creeping moisture). Also outside the longitudinal walls (82) there arises an air gap since the roof (84) and the strip (73) protrude from the longitudinal sheets. The construction of the body is, of course, limited by strength. A sufficiently strong container can be obtained, for example, with a body made of joists. In the example, use is especially made of five U-shaped frames joined by suitably dimensioned joists. The number need not be five but may be larger or smaller depending on the size of the container and the dimension of the joists. For instance the U-shaped frames can be delivered assembled by nail plate joints or the like. Finally, mention can be especially made of the manner in which a large surface is obtained in the joints; a large surface of course facilitates sealing of the container to prevent leakage of dust. The joists (71) create a large surface in the joints between the side walls (82, 83); the strips (72, 73) create a large surface in the joints between the bottom (81) and the side walls on the one hand and between the roof (84) and the side walls on the other hand.
[Summary] Summing up what has been described so far (in text and Figures), we consider that the invention can be defined as follows. The invention relates to the containers for pellets (or in general whole pieces, more or less large, of a material or a product), which are provided with an emptying device. Like many other containers it has walls: two longitudinal walls and two transverse walls, thus not yet specifying whether they are flat or parallel to each other. Like in many other containers of this type, the emptying device consists of active units, at least one, but preferably two, which can be moved between a lowered position and different degrees of raised positions. A common feature is also that there is a limited area (M), or a small number of such areas, close to the bottom of the container, from which the contents are emptied. What particularly distinguishes the invention from other containers with an emptying device is defined in the rest of the paragraph. First, the transverse walls are in substantial parts flat and parallel. Second, such an active unit comprises at least the components main sheet (1), side sheet (2), rotary shaft (3) and coupling (4): these have the properties, and cooperate with each other and with the container and with the pellets, as will now be described. The main sheet (1) is articulated by a joint (5) at the bottom of the container on an axis which is perpendicular to the transverse walls and positioned close to the emptying area (M). The main sheet is further characterised in that it has a width equalling the distance between the transverse walls and a length approximately equalling the distance from the joint (5) to a longitudinal wall. The side sheet (2) is articulated by a joint (6) to the rear edge of the main sheet (1) on an axis perpendicular to the transverse walls. Also the side sheet has a width equalling the distance between the transverse walls. The rotary shaft (3) extends between two of the walls, suitably, but not necessarily, between the transverse walls and perpendicular to the same. Each coupling (4), an active unit may have one or more couplings, is characterised in that it extends from the rotary shaft down to the main sheet close to the joint to the side sheet. During rotation of the shaft, the coupling is wound onto the shaft, resulting first in the main sheet being slanted up from the lowered position in order to make pellets fall down to the emptying area and, second, in the side sheet, by way of the joint (6), being carried along by the main sheet to prevent pellets from falling down under the main sheet. The latter also determines the minimum length of the side sheet.

Claims

A container with an emptying device for fuel pellets or other more or less large pieces of a material or of a product, the container having a shape comprising two longitudinal walls and two transverse walls, emptying occurring in a limited area (M), or a small number of such limited areas, adjacent to the bottom of the container, and the emptying device comprising at least one active unit which can be moved between a lowered position and different degrees of raised positions, characterised in that first the transverse walls are, at least in substantial parts, flat and parallel, and second said active unit comprises a main sheet (1) which has a width equalling the distance between the transverse walls and is articulated in the container on an axis which extends close to the emptying area (M) and is perpendicular to the transverse walls; and comprises a side sheet (2) which has a width equalling the distance between the transverse walls and is articulated to the rear edge of the main sheet on an axis perpendicular to the transverse walls; and comprises a rotary shaft (3) extending between two of the walls of the container inside the container; and third, during rotation of the rotary shaft, couplings (4) extending between the main sheet and the rotary shaft are wound onto the rotary shaft, resulting on the one hand in the main sheet being slanted up from the lowered position in order to make pellets fall down to the emptying area and, on the other hand, in the side sheet, which is carried along by the main sheet, preventing pellets from falling down under the main sheet.
A container with an emptying device as claimed in claim 1, characterised in that the rotary shaft extends between the two transverse walls perpendicular thereto in a position between the emptying area and a longitudinal wall, so that the horizontal component force of the couplings is directed towards the feeding area until the main sheet has been slanted up to a raised position at an angle greater than the angle of repose.
A container with an emptying device as claimed in claim 1 or 2, characterised in that the joint of the main sheet in the container comprises a block or blocks (5) fixed to the bottom of the container, which abut against the front edge of the main sheet.
A container with an emptying device as claimed in claim 1 or 2, characterised in that the main sheet is fixed by means of a quickly opening lock to the bottom of the container by way of said joint between the main sheet and the container.
A container with an emptying device as claimed in any one of the preceding claims, characterised in that the joint (6) between the main sheet and the side sheet comprises means, angle bars (61) or some other means to prevent the side sheet from falling flat on the main sheet when the container has been emptied of its contents.
A container with an emptying device as claimed in any one of the preceding claims, characterised in that the rotary shaft (3) has a blocking device, ratchet arrangement (9) or some other blocking device to control the movement of the active unit from the lowered position to a raised position.
A container with an emptying device as claimed in claim 6, characterised in that the blocking device comprises a cover (93).
A container with an emptying device as claimed in any one of the preceding claims, characterised in that the container has a body comprising U-shaped joists, and that the bottom of the container and the transverse walls are mounted on the inside of the U-shaped joists.
A container with an emptying device as claimed in claim 8, characterised in that the longitudinal walls are mounted on the outside of the U-shaped joists and that a strip (73) is fixed to the upper edge on the outside of the longitudinal walls.
A container with an emptying device as claimed in claim 8 or 9, characterised in that through holes in the joists constitute support bearings for said rotary shaft.