GB2035045A

GB2035045A - Telescopic duct for drying grain

Info

Publication number: GB2035045A
Application number: GB7935552A
Authority: GB
Original assignee: SIMPLEX OF CAMBRIDGE Ltd
Current assignee: SIMPLEX OF CAMBRIDGE Ltd
Priority date: 1978-10-20
Filing date: 1979-10-12
Publication date: 1980-06-18
Also published as: GB2035045B

Abstract

Duct apparatus for the treatment of material such as agricultural produce stored in bulk, comprising a main duct into which air or other treatment fluid can be introduced under pressure and a number of lateral ducts from which the fluid passes into the material heaped over the lateral ducts. The lateral ducts are telescopically contractible in length towards the main duct so as to remove all or most of the obstruction presented by the lateral duct.

Description

SPECIFICATION Duct apparatus for treating bulk material This invention relates to apparatus for the treatment with gaseous fluid of granular, fibrous or other material which is permeable to such fluid when stored in bulk, which apparatus is of the kind (hereinafter referred to as duct apparatus of the kind specified) comprising a main duct into which the treatment fluid can be introduced under pressure and a plurality of lateral ducts each communicating with and extending from the main duct so as in use to lie across the storage floor on which the said material is to be heaped so as to cover the lateral ducts and each of which lateral ducts has one or more apertures extending over or distributed along its length through which the treatment fluid passing into the lateral duct from the main duct can emerge at or near floor level for permeating said materials.

In some cases the main duct might be designed to be within the storage enclosure for the material so as to provide one or more of the walls bounding the floor area on to which the material is to be heaped. In other cases the main duct might be designed to lie outside the storage enclosure and the lateral ducts pass to it through apertures in the enclosure walls.

The treatment fluid may be a gas, vapour or gaseous suspension according to the nature of the material and the type of treatment to be carried out.

The invention is especially, although not exclusively, concerned with such apparatus for treating agricultural material such as seeds (for example grain) or plants (for example herbage) or roots (for example potatoes) and especially for drying or ventilating such material with air, which may be conditioned (for example heated) before supply to the lateral ducts.

The invention will be further described and explained with particular reference to its use for the drying of grain stored in bulk.

The drying of grain is frequently carried out in large grain sheds which may typically be 40 metres long by 20 metres wide. When grain is in such a store it is normally piled on the floor to a depth of about three to four metres.

If damp grain is stored, it will rapidly become unfit for consumption if steps are not taken to dry it thoroughly.

A conventional grain store therefore is usually fitted with a main duct extending along its entire length, positioned either along one wall or down the centre of the grain store. The main duct is fitted with large air blowers.

At one or both sides of the main duct, there are provided a plurality of lateral ducts. These are usually formed of expanded metal, perforated plate or the like and are in communication with the interior of the main duct so that the air supplied by the blowers is conducted along the main duct and distributed through the lateral ducts from which it can pass into the bulk of the grain heaped over the lateral ducts.

Clearly, it would be advantageous to be able to use mechanical handling means to put the grain in and to remove the subsequently dried grain from the bulk store but this has hitherto not proved easy to achieve because of the construction of the drying apparatus. Although the floor of the grain store is usually of flat concrete or the like, the lateral ducts impede the progress of any mechanical handling means and also prevent grain lorries from being brought into the store as it is being emptied.

Hitherto, the usual solution to this difficulty has been to make the lateral ducts in sections which have had to be manually dismantled and removed as the grain is being taken out of the store. This dismantling has to continue as the grain is being removed, to enable mechanical handling gear and lorries to be used in the grain store.

Clearly, this is wasteful of effort and tends to disrupt the removal of the grain, particularly as it is necessary to remove the upper layers of grain before the sections of the lateral ducts become accessible for removal.

An alternative which has been proposed is to form the lateral ducts as recesses in the concrete floor of the grain store and to cover them by means of flat metal grids of expanded metal or the like which are laid flush with the floor surface. This enables mechanical shovels and similar means to be used to remove the grain without obstruction but difficulties are encountered with grain falling through the mesh which subsequently needs to be removed for cleaning purposes. Furthermore the weight of the mechanical handling gear and in particular of grain lorries moving into the store tends to distort the mesh covers of the lateral ducts, making frequent replacement necessary. The presence of the mesh covered ducts in the floor tends to make it unsuitable for general storage purposes during the period when grain is not in store.

It is an object of the present invention to provide drying or treating apparatus which is capable of avoiding or reducing these disadvantages associated with the known grain drying apparatus.

According to the invention we provide a form of lateral duct for use in duct apparatus of the type specified which is arranged to be telescopically contractible in length towards the wall of the main duct from which it is designed to extend.

The lateral duct may in some cases be arranged to telescope completely into the main duct but in other cases may be arranged to telescope into a relatively small region immediately adjacent to the main duct.

Preferably in a duct apparatus of the type specified each of the lateral ducts is a telescopically contractible duct in accordance with the invention, but in some cases it might suffice if only some of the lateral ducts nearer the entrance to the storage enclosure are telescopically contractible, since this might suffice for clearing a sufficient floor area to permit the entry of mechanical handling apparatus or lorries.

The invention will be further described by way of example with reference to the accompanying drawings, which are purely schematic and in which Figure 1 shows a plan view of a bulk material store incorporating apparatus in accordance with the invention, for the treatment with gaseous fluid of the stored material, and which illustrates the general nature of the invention; Figure 2 shows a perspective view of part of a grain drying apparatus in accordance with the invention, and, Figure 3 shows a preferred form of lateral duct for use in accordance with the invention.

Referring first to Fig. 1, the store consists of a rectangular building having side walls 1 and end walls 1', one of which end walls incorporates double doors 2 giving access to the store.

Within the store, along one of the side walls 1, is fitted the main duct 3 of the grain drying apparatus and a number of lateral ducts 4 extend from the main duct 3 on and across the floor of the store. Only four lateral ducts are shown for convenience of illustration, but the number used will usually be greater than this. Likewise each lateral duct will usually contain more than four sections.

The main duct 3 is provided with an access door 5 and incorporates a blower 6 for introducing air at pressure into the duct, which air escapes into the store through apertures distributed along the walls of the lateral ducts.

In accordance with the invention, each of the lateral ducts 4 is formed in a number of sections which are arranged to telecope into each other towards the wall of the main duct.

For effecting this telescoping each lateral duct is provided internally with a cable 7 which passes from a bar 8 fixed across that end of the lateral duct which is further from the main duct to a winch 9 mounted within the main duct. By operating the winch the telescopic sections can be successively drawn into each other so as to lie wholly within the section nearest the main duct, the lateral ducts nearest the doors 2 being shown fully contracted in this way.

Referring now to Fig. 2, this illustrates the nature of the main duct and lateral ducts of a grain drying apparatus in accordance with the invention fitted into a grain store.

The apparatus comprises a main duct 10 designed to be fitted against and along one wall of the grain store, and which is formed from heavy metal sections provided with reinforcing ribs as shown. It will be appreciated that the force exerted on the main duct by the grain will be considerable since the grain, a portion of which is indicated at 11, will be stacked to a depth of three to four metres high and the duct 10 will be more or less completely buried in the grain in use, so that it should be strong enough to withstand this.

The main duct 10 is provided with an access door 12 through which access can be had to the ventilating equipment and to the winches to be described hereinafter.

In the example shown, lateral ducts each in accordance with the invention and generally indicated at 1 3 are provided along the side of the main duct within the grain store enclosure. Each lateral duct can be telescopically extended from the main duct 10 to the opposite side wall of the grain store enclosure but, for purposes of illustrating the construction used in the present invention, the overall length and number of sections of the lateral ducts have been reduced for clarity.

It will be seen that each lateral duct 1 3 is in a plurality of sections, four of which are shown at 14, 15, 16 and 17. Each section has a sheet metal top 1 8 which is capable of withstanding the load of the grain 11 and each lateral duct further has side walls 1 9 of expanded metal, metal mesh or the like. The cross-section of each of the sections 14 to 1 7 shown in the drawing in rectangular but it will be appreciated that any suitable form of lateral can be used and in particular the crosssection may be inwardly tapered towards the top, may be triangular or even circular if desired.

The main feature of the lateral ducts is that each section is capable of being slidably received within the next. Thus, the section 1 7 has a larger cross-section than the section 1 6 and so on. Each section can be provided with any suitable form of slide means to allow for smooth sliding movement of one section into another.

Longitudinal guiding means for reducing the possibility of sideways displacement of the sections relative to each other will usually also be desirable.

In general, since the typical width occupied by a lateral duct in a grain store is about eight metres, it will be possible to subdivide each lateral into eight interfitting sections of about one metre each, the laterals furthest from the main tunnel being about 0.12 metres in depth and those adjacent the main tunnel being about 0.35 metres in depth. Each section is provided with a suitable end formation to receive the next adjacent smaller section without allowing ingress of large quantities of grain.

Each lateral duct is provided with a cable 20 which extends throughout its length and is secured to a suitable bar or similar anchor 21 at the end of the lateral duct remote from the main duct 10. The cable 20 passes through the centre of the lateral duct to a winch 22 mounted within the main duct. The winch 22 may be hand or mechanically operable.

In use, the lateral ducts are extended across the floor of the grain store enclosure to their full lengths and, since the grain store is empty at this time, extension can be readily carried out by hand. Alternatively, a winch and cable arrangement may be attached externally to the anchor bar 21 to extend the lateral ducts.

Grain can then be loaded into the store by any suitable means. It will be appreciated that the lateral ducts may need only be extended as and when they are required and this enables the grain to be brought into store using mechanical means.

When the grain is in position, air blowers (not shown) provided in or in communication with the main duct can be started up and the drying process will proceed conventionally with air passing along the lateral ducts and out through the mesh side walls 1 9. The fact that the lateral ducts are of smaller crosssection at positions remote from the main ducts need not cause any problems with the distribution of air since the air volume along the lateral duct will in any case tend to drop towards the end remote from the main duct 10 due to dissipation of the air into the grain taking place along the lateral duct.

When it is desired to remove the grain from store, the blowers are stopped and it is then possible to enter the main duct by the access door 1 2 to operate the winches 22 and draw in telescopically the sections of each of the lateral ducts 1 3. The sections may in some cases be arranged to be withdrawn wholly into the main duct 10 or in other cases may simply telescope into the final section 1 7 immediately adjacent the main duct. In the latter case, the floor of the grain store enclosure will not be completely unobstructed but the obstruction will be relatively small compared with the obstruction provided by an entire fully extended lateral duct.

The lateral ducts are arranged to be contracted in length while the grain is still in the store and before any steps have been taken to remove it. When the lateral ducts have been telescoped, unloading can take place using mechanical handling apparatus with maximum efficiency since the floor area is unobstructed or substantially unobstructed. Access is also possible for lorries without substantial risk of damage to the grain store structure and grain drying apparatus.

Referring now to Fig. 3 this shows a preferred form of lateral duct designed to reduce the winching force required to produce the telescopic contraction under the weight of the superposed grain in use.

The duct is shown as formed in eight sections 30 each of which is perforated, as indicated in part at 31, to permit air to escape from its interior in use.

Each section consists of a metal sheet bent to Gothic arc shape, i.e. to form two convex arcuate sides 32, 33 meeting at a central longitudinal ridge 34, and welded along their lower sides to a bottom sheet in the form of a tray 35 having upturned edges 36.

For each section except the last (i.e. the section designed to telescope into it), the tray 35 extends as at 37 towards the section for somewhat less than half the length of that section, so as to provide a base on which that section can slide and so that the upturned edges of the tray provide longitudinal guidance means preventing excessive bending (i.e.

sideways displacement in the manner of jackknifing) of the two sections relative to each other. Such excessive bending would, of course, greatly increase the telescoping force required if it did occur. Preferably zinc-coated steel is used for the sections for reducing the sliding friction.

Across the free end of the last section is welded a bar 38 of width sufficient to gather up the sections as they are telescoped together.

To the bar 38 is attached the retractor cable 39 which passes within and through all of the sections for engagement by the retractor winch (not shown).

It will be appreciated that the arrangements described above enable all the grain to be removed without danger of substantial quantities of grain remaining trapped in crevices since the floor area is unobstructed and can be cleaned out readily. It will also be appreciated that particularly where a power winch 22 is used to telescope the lateral ducts, the telescoping can be carried out by one man in a relatively short time compared with the dismantling of non-telescoping sections as used hitherto.

It will also be appreciated that various modifications can be made to the apparatus as described above. For example, instead of each lateral duct being provided with its own winch, a single portable winch might be used, to be carried to each lateral duct in turn and attached to its retractor cable when telescoping of that duct is required.

Also the lateral ducts might in some cases be made of a suitably strong plastics material and/or the cable could be in the form of a chain or rope; all such possible replacements for the cable are to be understood as covered by the term "cable".

Also in some cases the main duct might be formed integrally with the wall of the storage enclosure.

Claims

1. A lateral duct designed for use in duct apparatus of the kind specified for the treatment of granular, fibrous or other permeable material stored in bulk, which lateral duct is formed by a number of telescopically interfitting sections so as to be telescopically contractible in length towards the end designed to communicate with the main duct in use.

2. A lateral duct according to Claim 1 wherein the interfitting sections are provided with longitudinal guidance means with reduces the extent to which the sections can be displaced sideways relatively to each other.

3. A lateral duct according to Claim 2 wherein the longitudinal guidance means consists of a forward extension of the one section bottom in the form of a tray over which the next and smaller section in the telescopic sequence can slide and which tray has upturned edges which bound the sides of the said next section.

4. A lateral duct according to any preceding claim fitted with operating means for effecting the telescopic contraction in length from within the main duct.

5. A lateral duct according to Claim 4 wherein the said operating means consists of a cable secured to the end of the lateral duct designed to be remote from the main duct and which cable passes within the lateral duct to its other end so as to be attachable to a winch housed within the main duct.

6. A lateral duct according to any preceding claim consisting of a number of telescoping sections which are designed to telescope into a relatively small region adjacent the wall of the main duct.

7. A lateral duct according to Claim 4 wherein said relatively small region consists of the section which lies nearest the wall of the main duct in use.

8. A telescopically contractible lateral duct which is constructed and designed to operate substantially as shown in and hereinbefore described with reference to Fig. 3 of the accompanying drawing.

9. Duct apparatus of the kind specified for the treatment with gaseous fluid of granular, fibrous, or other permeable material stored in bulk and which comprises a main duct having a number of lateral ducts extending therefrom, wherein one or more of the lateral ducts consists of a telescopically contractible lateral duct in accordance with any one of Claims 1 to 8.

10. Duct apparatus according to Claim 9 wherein each of the lateral ducts consists of a telescopically contractible lateral duct in accordance with any one of Claims 1 to 8.

11. Duct apparatus according to Claim 9 or Claim 10 wherein the main duct is designed to be housed within the storage enclosure and is provided with an access door through which an operator can gain access to the operating means for the telescopic lateral ducts.

1 2. Duct apparatus of the kind specified which is contructed substantially as shown in and hereinbefore described with reference to Fig. 2 or Figs. 2 and 3 of the accompanying drawing.

1 3. A store for granular, fibrous or other material permeable to gas in bulk and which is fitted with duct apparatus in accordance with any of Claims 9 to 1 2 for the treatment of the stored material with gaseous fluid.

14. A store according to Claim 1 3 suitable for the drying or ventilating of agricultural produce wherein the treatment fluid is air and the main duct includes or communicates with means for introducing air under pressure into the main duct.