GB2268039A - Apparatus for ventilating air/gas/liquid-gaseous mixtures e.g.to plant material in containers - Google Patents

Abstract

The apparatus includes a system of frames 1 providing apertures 5 aligning with apertures in pallet boxes 6 and with ducts 9 attached to frame members. The ducts are subject to positive or negative pressure by fans mounted at the end of the ducts. The apparatus can be used for drying, cooling, warming, and fumigating plant material in the containers (boxes). Figures 6-9 show flaps to close off apertures 5. Details of the framework and the fabric ducts 9 with air straightener (Figure 10) and duct termination piece (Figure 11) are given. <IMAGE>

Description

APPARATUS FOR VENTILATING PLANT MATERIAL IN CONTAINERS The present invention relates to apparatus for providing ventilating air, gas or liquid-gaseous mixtures, especially, but not exclusively, to plant material held in suitable containers. The apparatus is particularly useful for forcing air through living plant material such as vegetables, fruit, bulbs, corms and seeds for drying, cooling, fumigating, warming and removal of the products of respiration.

Ventilation apparatus for forcing air through plant material are termed positive ventilation systems in that they attempt to force air past each and every item in each container in a uniform manner.

The form of positive ventilation system that most closely resembles the present invention is the "letterbox system". It consists of a duct, bounded on all sides by solid material, which is subjected, most commonly, to positive pressure by means of a fan or fans. Rectangular apertures, which resemble the aperture in a mail box, are made in the duct to match corresponding apertures in containers holding the plant material. The containers are stacked up in rows, the first box in each row touching the duct. The apertures of the containers act as a conduits for the air to flow. The containers have porous bases. By blocking the aperture of the last container in the row on the side farthest from the duct, air is caused to move from the conduit formed by the containers through the plant material itself.

Containers are usually ventilated in pairs of layers, with the airflow flowing downwards through the lower layer of containers and upwards through the upper layer of containers. Two or three pairs of layers of containers are stacked vertically to form a stack four or six containers high.

Containers may be stacked in odd numbers with either all or a proportion of apertures ventilated.

The letterbox duct is most commonly subjected to a positive pressure. It can be subjected to negative pressure causing the airflows to be reversed and the letterbox duct apertures to become inlets.

A modified form of the letterbox duct is the Posi-vent R duct invented by the present applicant which consists of a high efficiency low pressure capability fan and tapered fabric duct fixed in a horizontal plane to the apertures of containers built into a stack of 64 to 80 containers. Outlets in the duct allow air to flow from the duct into the pallet apertures. Bungs of non porous material located at the far end of the conduit formed by the container apertures prevent the air escaping from the conduit and cause air movement through the plant material in a similar manner to letterbox ventilated containers.

It is an object of the present invention to achieve apparatus for causing air or gaseous fluid to flow through material in containers in a positive way, using a framework in a single vertical plane with apertures to match the containers, and one fabric or solid duct, preferably tapered for even air distribution, per layer or pair of layers of containers, with air movement being caused by the pressure created by fan or fans. It differs from the letterbox duct in there being only one frame and no cladding of sheet material.

According to the present invention there is provided an apparatus for causing air or gaseous fluids by means of a frame having a series of apertures or continuous aperture to match apertures of containers at each container or pair of layers of containers, or a combination of the two. The duct or ducts are connected to the frame by clamps or suitable fixings. The frame is supported by struts or members attached to the building structure or fabric or secondary members themselves attached to the building structure or fabric. The fixings are of sufficient strength to withstand the loads imposed on it by forklift trucks when the containers are being placed against the frame.

Air or gaseous fluids are caused to flow through the ducts by fans located at the end of each duct, or by fans causing a positive or negative pressure within a chamber, with apertures in the chamber to allow passage of air or gaseous fluid to or from the ducts.

When the ducts are made from fabric, the ducts are pressurised and air is forced out of the ducts.

With ducts of solid material, the ducts may be under positive or negative pressure, allowing air movement to be caused to flow into or out of the ducts.

It is particularly preferred that the ducts should be tapered to make the flow of air to or from the apertures or aperture more uniform. It is particularly preferred that where fans are fitted in line with the duct, air straighteners should be fitted to remove the swirl caused by the rotating fan blades. To ensure that the first half container is not starved of air the fan should either be set back one fan diameter from the first aperture andior tilted at an angle of 100 so as to direct air into the first aperture.

In yet another independent aspect, there may be provided slides or hinged flaps to shut off individual apertures. These may be connected in a vertical plane and operated together or separately. A walkway above the ducts, between the floor and bottom duct or between any two ducts allows access to operate slides or flaps individually.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is an elevation of the apparatus embodying the invention for positively ventilating produce but with the fan and ducts removed for clarity.

Figure 2 is a plan of the apparatus shown in Figure 1, with boxes stacked in two blocks against the frame.

Figure 3 is a cross sectional elevation of the framework and ducts on XX in Figure 1; Figure 4 shows the detailed construction of three frames A, B and C of the structure in Figure 1; Figure 5 shows the method of fixing the tapered fabric duct to a horizontal aperture of a frame; Figure 6 shows the location of the two flaps that close off each aperture; Figure 7 is a sectional plan on AA of Figure 6 showing the location of flaps and their operating linkage; Figure 8 is the sectional elevation on BB of Figure 6 showing the right hand flap; Figure 9 is the sectional elevation on CC of Figure 6 showing the flap operating linkage; Figure 10 is a cross section of the air straightener located in each duct at the exit from each fan; Figure 11 is the cross section of the termination piece for the end of the tapered fabric duct.

Referring to Figures 1, 2, 3, and 4, apparatus for providing positive ventilation of plant material is indicated in Figure 1 and comprises a system of steel frames 1 bolted together. The frames 1 are fixed to the floor by expansion bolts in the concrete and supported by horizontal struts 2 joined to the building stanchions 3 and intermediate I-section columns 4 attached to the building wall 38.

Apertures 5 in the frames align both vertically and horizontally with apertures in the pallet boxes 6 stacked against the frames. The frame apertures 5 coincide with the pallet box apertures of the second, fourth and sixth high box in the stack. Blanking angled plates 34 on either side of the frame apertures are sized to prevent air escape from the sides of the boxes when they are stacked in either of two modes.

Mode one, shown in Figure 2, is for ventilating boxes which have significant gaps in them. Such boxes allow approximately 75% of the air to escape from them without first having passed through the plant material. To partially counteract this problem, boxes 6 are stacked in a block four wide 7 and one five wide 8 with a gap of 400mm between blocks. This allows access, should the store operator wish to seal gaps in the boxes to improve the efficiency of ventilation.

Where an odd number of rows are to be stacked one frame B, Figure 4 is made narrower and three rows of boxes are stacked together.

Mode two is not shown and is for boxes having ends with no ventilation gaps in them. Airflow loss is approximately 50% compared to the 75% with boxes with end ventilation gaps. Boxes are stacked together in pairs with gaps of 200 mm between them. This allows any row to be removed by forklift truck without moving another row.

Three tapered fabric ducts 9 in a horizontal plane are attached to the frames 1 at levels coinciding with the frame apertures 5. The inlet of each duct has a fan 10 and air straightener 11.

Figure 4 shows the detailed construction of three frames 1. The basic rectangular frame 12 is made from mild steel angle. Horizontal cross members 13 of mild steel act as braces to stiffen the frame 12, act as aperture outlets from the ducts 9, and act as support for the tapered ducts 9. The horizontal members 13 abut each other at the junction between each frame and are sealed with mastic during erection to ensure air from the duct does not leak from the frame.

The horizontal members 14 on frames connect the frames via horizontal struts 15, to stanchions 3 and columns 4, to support the frames against horizontal loads and also carry the catwalk 16.

Figure 5 shows how the tapered fabric ducts are attached to the frame aperture horizontal members 13. The ducts are constructed as a flat tapered fabric sheet with rope 41 sewn into the selvage.

Angle clamps 16 fit over the fabric 9 and rope 41 and are clamped into position by fitting a wedge washer 17 over the stud 18 and tightening the nut 19.

Figure 6 and 7 show the two flaps 20 that serve to close off any aperture 5 when required. The mild steel plate 21 fitted to the centre of the each aperture 5 supports the flap pivot pins 22 attached to the inside edges of the two flaps 20 while the blanking angled plates 34 support the outside flap pivot pins 24. The pivot pins 22 and 24 are connected to the flaps by rivets. The flaps are operated by a lever 28 connected to a tube 29 that travels in a vertical direction.

Figure 8 shows the cross section on BB of Figure 6 of the flap 20 and aperture 5. The flaps 20 are made of galvanised steel bent at their top and bottom edges 25 to give the flaps stiffness and to prevent the flaps jamming when in the closed position 26. The flaps 20 rotate through 60 deg and are in the horizontal position when open 27.

Figure 9 shows the linkage for operating the flaps 26 and Figure 7 shows the location of the flaps and linkage relative to the frame aperture 5.

The operating crank 28 is located between the edge of the frame 12 and the edge of the blanking angled plates 34. A slot 31 on the crank locates with a steel pin connected to pipe 29 which is free to travel in a vertical direction. The pipe slides through holes 32 drilled in the horizontal angle iron member 13 above and below the aperture 5. To close the flap the tube is moved upwards until crank 28 reaches position 35. To open the flap the tube is moved downwards until the crank reaches position 36.

So that all three flaps within a single frame 1 can be operated simultaneously a steel rod 40 is fitted concentrically through the three tubes 29 located vertically below one another. The tubes are clamped to the rod by a thumb screw 41. The rod 40 is common to all three flaps 20 in the three apertures of the frame. There are two flaps 20 per aperture 5, six flaps per frame 1 and two operating rods 40 per frame.

To open the flaps 20 the rod 40 is pushed manually downwards. To shut the flaps the rod is pulled vertically upwards.

If one aperture 5 only in a frame is to be closed, the thumb screw 41 is loosened allowing the tube 29 to slide up the rod and so close the flap.

Figure 11 shows the air straightener 11 located in each duct 100mm clear of the fan 10 blades. The straightener is 1.0 m in length and consists of galvanised steel sheets 46 formed into a cross and fixed by rivets 44. The straightener is supported by brackets 45 connected to lugs 42 welded on to frame 5 horizontal aperture members 13.

The tapered fabric duct 9 (Figure 1) at its widest end is wrapped round a steel ring 47 (Figure 11) attached to the fan diaphragm plate and secured with a draw cord 51 in the selvage of the fabric and tied by a knot 48.

The duct termination piece 49, made of steel plate, is welded to the leftmost frame aperture 5 (Figure 1). The end of the tapered duct 9 is wrapped round the termination piece 49 and secured with a draw cord 52 tied by a knot 50.

Claims (7)

1. An apparatus for ventilating plant materials in containers, comprising: a support frame; ventilating ducts with slots provided along their length to correspond directly to the ventilation aperture in the plant containers; a system for providing positive or negative pressure to the ducts; and a set of non porous bungs to enable block of the end of the ventilated conduit in the plant containers.

2. An apparatus for ventilating plant material in containers, as claimed in Claim 1 wherein the ventilating ducts are supported by the frame, the frame being attached to the building structure and the floor.

3. An apparatus for ventilating plant material in containers, substantially as described herein with reference to Figures 1-11 of the accompanying drawings.

Amendments to the claims have been filed as follows 1. An apparatus for ventilating plant material held in containers comprising of a tapered or tapered ducts, with apertures corresponding to apertures in the containers, mounted on a rigid framework, causing air to flow between the ducts and the containers.

2. An apparatus for ventilating plant material held in containers as in Claim 1 with tapered ducts made of fabric material.

3. An apparatus for ventilating plant material held in containers as in Claim 1 and 2 with the duct or ducts inflated by fan(s).

4. An apparatus for ventilating plant material held in containers as in Claim 1 with apertures capable of being closed off by rotating flaps or slides.

5. An apparatus for ventilating plant material held in containers as in Claim 1 with a tapered duct made of rigid material wherein the air is drawn from the containers into the duct due to a negative pressure within the duct.

6. An apparatus for ventilating plant material held in containers as in Claim 1 but specifically for the ventilation of potatoes, vegetables and bulbs.

7. An apparatus for ventilating plant material held in containers substantially as described herein with reference to Figures 1 - 11 of the accompanying drawings.