GB2457509A

GB2457509A - Conveyer freezer

Info

Publication number: GB2457509A
Application number: GB0802965A
Authority: GB
Inventors: Kenneth Chandler
Original assignee: IQF Ltd
Current assignee: IQF Ltd
Priority date: 2008-02-18
Filing date: 2008-02-18
Publication date: 2009-08-19
Anticipated expiration: 2028-02-18
Also published as: GB0802965D0; GB2457509B

Abstract

A conveyer freezer, for chilling or freezing a product, comprises an insulated container 2, an inlet 22 and an outlet 24, and a support structure 10, (12, fig.5) disposed within the container. The insulated container is provided with a refrigeration unit for chilling or freezing the product passing through the container. The product enters the container through the inlet and exits the container through the outlet which is located at a lower level than the inlet. The support structure carries an array of at least four vertically stacked conveyer belts 14, where each conveyer belt is arranged to move in a direction opposite to the conveyer belt below or above it and is positioned so that the array forms a cascade carrying the product along a path from the inlet through the container to the outlet. Preferably, the array consists of an even number of conveyer belts and the inlet and outlet are located on a common wall of the container. The refrigeration unit may be located at an end of the container remote from the common wall. Preferably, the support structure is provided with wheels (38, fig.4) and/or rollers travelling along tracks (40, fig.4) in the floor of the container, enabling the support structure to be moved in and out of the container. The product may be a food product such as fruit, vegetables or seafood.

Description

24575Q9

A FREEZER

This invention relates to a freezer and more particularly to an IQF (Individual Quick Freeze) conveyer freezer.

Background of the Invention

IQF freezers are generally used for Individual Quick Freezing (IQF) of foods and in particular foods of relatively small particle size, e.g. ranging from 4 to 50 mm in diameter. Typical products include vegetables such as legumes (e.g. peas), corn products, mushrooms, diced or cut vegetables; and fruits such as berries, and diced and sliced fruits; and seafood such as prawns and shrimps. By freezing vegetable products rapidly, the ice crystals that form within the product are relatively small in size and do not rupture the cell walls leading to loss of structural integrity.

Examples of freezers include immersion freezers (see Canadian patent number CA 2 198 538) in which products are frozen by immersion in a liquid refrigerant, tunnel freezers (see US patent number 4078398, and international patent applications WO 01/04554 and WO 97/43588), spiral immersion conveyor freezers (see international patent application WO 02/224 70), Other examples of freezers are disclosed in international patent application WO 0 1/44733 (York International Corporation), Japanese patent application JP 2000- 171144 and Spanish patent application ES 2168910.

Summary of the Invention

The present invention provides an improved freezer which is capable of rapidly freezing products such as vegetables and fruit by IQF. The freezer of the invention *S.

is compact and portable making it particularly suitable for use in the field, for :: example at the site of vegetable or fmit harvesting. S..

Accordingly, the present invention provides a conveyer freezer for chilling or freezing a product, the conveyer freezer comprising: an insulated container provided with a refrigeration unit for chilling or freezing product passing through the container; an inlet through which product can enter the container; an outlet through which product can exit the container, the outlet being located at a lower level than the inlet; a support structure disposed within the container, the support structure carrying an array of at least four vertically stacked conveyer belts wherein each conveyer belt is arranged to move in a direction opposite to the conveyer belt below or above it and is so positioned that the array forms a cascade carrying the product along a path from the inlet through the container to the outlet.

As indicated above, the Conveyor freezer of the invention fimctions as an IQF freezer.

By providing at least four conveyor belts in a vertically stacked arrangement, a sufficiently long path of travel through the container is provided to ensure that the product has time to freeze, whilst minim ising the length of the refrigerated container. Conveniently there are five or six conveyor belts.

It is preferred that the array consists of an even number of conveyer belts because the inlet and outlet can then be located on the same wall (common wall) of the container. The common wall can then be made at least partially removable to allow access to the interior of the container. For example, the common wall can comprises one or more doors, e.g. a pair of doors. The doors can be opened to allow access to the Container interior.

The refrigeration unit is typically disposed at an end of the container remote from * the common wall on which the inlet and outlet are located. Preferably the refrigeration unit is located in a closed compartment separate from a main interior S...

space in which the support structure and array of stacked conveyer belts are 25 disposed.

I

In order to prevent fogging within the container and to assist in maintaining the low * :* temperature within the container, the inlet may take the form of an opening protected by an air curtain. The outlet also preferably takes the form of an opening protected by an air curtain. The air curtain is typically a sheet or flap or a flexible material such as a plastics material.

The inlet and outlet may each take the form of a substantially horizontally oriented elongate slot ("letterbox opening") of sufficient height to accommodate a desired range or products.

Product can be introduced into the inlet by means of a product feeder conveyer belt which in use extends from an external product processing or loading station through the inlet and is positioned so as to drop product onto the surface of the uppermost conveyer belt which is arranged to convey the product away from the inlet. Thus the product feeder conveyer belt is arranged to travel in the same direction as the uppermost conveyer belt in the array.

Frozen or chilled product can be removed through the exit by means of a product collector conveyer which can be positioned in line with or below the lowermost conveyer belt in the array and which is arranged to travel in the same direction as the lowermost conveyer belt in the array. The product collector conveyer can be set up to carry frozen or chilled product to a packing or transport station.

The support structure typically comprises one or more frame members upon which are mounted the conveyer belts. The frame members are preferably linked to form a self supporting framework. In order to assist the maintenance and cleaning of the container interior and the conveyer belt stack, the support structure is preferably provided with means enabling it to be moved in and out of the container.

: For example, the support structure (e.g. support framework) can be provided with I...

wheels or rollers or a combination thereof to allow the support structure to be * wheeled or rolled out of the container. In order to assist movement of the support * 25 structure in and out of the container, two or more substantially parallel tracks along which the wheels can travel may be provided on a floor or base of the container.

External tracks which in use are disposed externally of the container and which connect to or abut against the tracks within the container may also be provided so as to facilitate movement of the support structure and array of conveyer belts out of the container.

In order to increase the rate of cooling or freezing of the product, an ancillary cooling means may be disposed within the container. The ancillary cooling means can comprise means for blowing a stream of chilled air over the product. For example, the ancillary cooling means may comprise one or more (e.g. two or three) air knives. One or more conduits (e.g. pipes, tubes or flexible hoses) may be used to convey chilled air collected from the lower regions of the container up to the air knife or knives. Typically, at least the uppermost (first) conveyer belt has an air knife directing chilled air onto products being conveyed along the said uppermost conveyer belt. Preferably, the conveyer belt (the second conveyer belt) beneath the uppermost conveyer belt also has an air knife directing chilled air onto products being conveyed along the said second conveyer belt. More preferably, the third conveyer belt from the top also has an air knife directing chilled air Onto products being conveyed along the said conveyer belt. Thus, in a preferred embodiment of the invention, three air knives are provided, one onto each of the top three conveyer belts in the array.

The conveyer freezer of the invention may be used for chilling or freezing a wide range of different types of product. Particular types of product are those (e.g. food products) where rapid freezing is required. Specific examples of products that may be frozen or chilled using the conveyer freezer of the invention include in particular foods of relatively small particle size, e.g. ranging from 4 to 50 mm in diameter.

Typical products include whole vegetables such as legumes (e.g. peas), corn products, mushrooms; chopped or cut vegetables; whole fruits such as berries; chopped or sliced fruits; and seafood such as prawns and shrimps. p. *

The conveyer freezer of the invention may be used in conjunction with other St. elements of a product (e.g. food) processing facility including one or more processing stations such as a washing station, a drying station, a filling station, a packing station, a sorting station, a forming station, a cutting station, or a stenuising or pasteurising station.

In another aspect, the invention provides a conveyer freezer as defmed herein and one or more product processing stations as hereinbefore defined.

In a further aspect, the invention provides a method of freezing or chilling a product (e.g. a food product), which method comprises passing the product though the inlet of a conveyer freezer as defined herein and conveying the product along the path through the freezer to the outlet over a period of time sufficient to bring about freezing or chilling of the product.

In a further aspect, the invention provides an apparatus comprising a support structure carrying an array of at least four vertically stacked conveyer belts as defined herein.

Further aspects of the invention will be apparent from the specific description below and the drawings appended hereto.

Brief Description of the Drawings

Figure 1 is side sectional elevation of a conveyor freezer according to one embodiment of the invention.

Figure 2 is a view from direction D of the conveyor freezer of Figure 1.

Figure 3 shows the conveyor freezer of Figure 2 but with the end door omitted.

Figure 4 is is an enlarged view of the region marked A in Figure 1.

Figure 5 is an isometric view of part of the Conveyor freezer of Figures 1 to 4, but with the end door omitted and the support frame and stack of conveyer belts s.' partially withdrawn from the container.

Detailed Description of the Invention

The invention will now be illustrated in greater detail, but not limited, by reference to the specific embodiments illustrated in the drawings. S *

Figure 1 shows a conveyor freezer according to one embodiment of the invention.

The freezer comprises an elongate box-like insulated freezer container 2 which may be of a standard commercially available type. Purely by way of example, the container can be from 6 to 15 metres in length, from 2 to 3 metres in width and from 2 to 3 metres in height. The container can conform to ISO container standard sizes. The interior of the container 2 is divided into two compartments; a smaller compartment 4 at one end which houses a refrigeration and freezing unit and the associated controls; and a larger compartment 6 which is closed by a removable end wall or door 8. The removable end wall has two "letter box" openings, one (22) at the top of the wall and one (24) at the bottom of the wall. The upper opening 22 functions as an inlet through which products to be frozen can be introduced into the container and the lower opening 24 functions as an outlet through which frozen products can exit the container. The two openings are partially covered by air curtains 26, 28 which serve to prevent warm air entering the container and minimise or stop fogging.

Mounted on an external wall of the container is a control panel 7 which can be used to control the movement and speed of the conveyer belts, and hence the residence time of the products in the freezer.

Inside the larger compartment 6 is a framework comprising upright frame members 10, cross members 12 (see Figure 5) and longitudinal frame members (not shown), each of which may be formed from stainless steel or powder coated steel.

Mounted on the framework are six conveyer belts 14 and their associated rollers 16 and variable speed drive motors (not shown). The drive motors are heated to prevent freezing. The Conveyer belts may be stainless steel mesh belts or belts made of a food grade non-stick plastics material such as PTFE. Belts formed from p...

such materials are commercially widely available. The six conveyor belts are * * 25 arranged in a staggered configuration with the ends of the second, fourth and sixth belts protruding in the direction of the compartment 4 and the ends of the first, third and fifth conveyor belts protruding in the direction of the door 8. Guide ramps 18 *:* are provided at the protruding ends of the second, fourth and sixth belts whilst guide ramps 20 are provided at the protruding ends of the third and fifth conveyor belts.

The drive motors for the conveyor belts are set up so that the first, third and fifth conveyor belts move in an anti-clockwise direction and the second, fourth and sixth belts move in a clockwise direction. In this way, the six conveyor belts and the guide ramps provide a path along which products can move from the inlet opening 22 through the container to the outlet opening 24.

The refrigeration and freezing unit in the smaller compartment 4 is able to create a low enough temperature (e.g. lower than -20°C) to bring about freezing but, to increase the rate of freezing, an ancillary means of cooling is provided. This takes the form of an array of three air knives 31, 33 and 35 fed by flexible tubes 37 (only one of which is shown) which are attached to upright frame members 10 and collect chilled air through an inlet at the bottom of the container. The chilled air from the bottom of the container is pumped up to and out of the air knives at the top of the container by means of the 3 horse power motorised pump 30, each of the air knives directing a stream of chilled air onto one of the uppermost three conveyor belts. In this way, products such as foods (e.g. vegetables) that require rapid freezing in order to avoid structural damage (e.g. plant cell rupture caused by the slow formation of large ice particles) can be frozen at the necessary speed.

In use, the conveyer freezer is coupled to a pair of external conveyor belts, an inlet feeder conveyor belt 32 and an outlet collector conveyor belt 34. When the products being frozen are vegetables, the inlet feeder conveyor belt is typically linked to a cleaning station for cleaning the vegetables prior to freezing. The inlet feeder conveyor belt extends through the inlet and deposits products onto the top of the uppermost conveyor belt in the stack. The products pass along the uppermost conveyor belt where they are subjected to chilled air from the air knife which brings about rapid chilling. At the end of the uppermost (first) conveyor belt, the partially frozen products fall off the end onto a guide ramp 18 and then travel in the reverse *. direction along the underlying second conveyor belt, again passing through the air knife. At the end of the second conveyor belt, the products cascade down onto * guide ramp 20 and back along the third conveyor belt where they are exposed to a fmal blast of chilled air from the air knife. After travelling along the remaining conveyor belts in the cascade, the products reach the outlet where they tumble onto the outlet collector conveyor belt 34. The outlet collector conveyor belt may be connected to another processing stat;uch as a packing station where the frozen product is prepared for transport.

From time to time, the interior of the container will require cleaning and/or maintenance. In order to enable cleaning and maintenance, the framework and conveyor belt assembly is constructed so that it can be moved out of the container once the door 8 has been removed or opened. To assist movement of the framework and conveyor belt assembly, the foot of each of the upright frame members is provided with a wheel 38. The wheels 38 on both sides of the framework rest in a pair of parallel tracks 40. The tracks can be connected to or abutted against a pair of external tracks 42 (see Figure 5) thereby enabling the entire framework and conveyor belt assembly to be rolled out of the container.

The conveyor freezer of the invention has a number of important advantages over known types of freezer. Firstly, because of the stacking of the conveyor belts, the overall size of the freezer is reduced. It is much shorter than conventional tunnel freezers and less complex than spiral conveyer freezers. The simplicity of construction means that it is typically less expensive to construct than many known types of freezer. Secondly, its compact shape and the fact that it is self contained means that it is portable. It can therefore be transported to the location where it is required, connected up to a power supply or a generator and feeder and set up quickly and easily. It is therefore of particular use, for example, in the freezing of vegetables, since it can be taken to the place where the vegetables are grown, thereby enabling the vegetables to be frozen within a very short period after being harvested.

iuivaIents It will readily be apparent that numerous modifications and alterations may be made to the specific embodiments of the invention described above without departing from the principles underlying the invention. All such modifications and alterations are intended to be embraced by this application.

Claims

CLAIMS1. A conveyer freezer for chilling or freezing a product, the conveyer freezer comprising: an insulated container provided with a refrigeration unit for chilling or freezing product passing through the container; an inlet through which product can enter the container; an outlet through which product can exit the container, the outlet being located at a lower level than the inlet; a support structure disposed within the container, the support structure carrying an array of at least four vertically stacked conveyer belts wherein each conveyer belt is arranged to move in a direction opposite to the conveyer belt below or above it and is so positioned that the array forms a cascade carrying the product along a path from the inlet through the container to the outlet.
2. A conveyer freezer according to claim 1 wherein the array consists of an even number of conveyer belts and the inlet and outlet are located on a common wall of the container.
3. A conveyer freezer according to claim 2 wherein the said common wall is at least partially removable to allow access to the interior of the container.
4. A conveyer freezer according to claim 3 wherein the common wall comprises one or more doors.
5. A conveyer freezer according to any one of claims 2 to 4 wherein the refrigeration unit is disposed at an end of the container remote from the * * common wall on which the inlet and outlet are located. * S S.
6. A conveyer freezer according to any one of the preceding claims wherein the inlet takes the form of an opening protected by an air curtain. *S
7. A conveyer freezer according to any one of the preceding claims wherein the outlet takes the form of an opening protected by an air curtain.
8. A conveyer freezer according to any one of the preceding claims wherein a product feeder conveyer belt is provided that conveys product through the inlet into the container, the product feeder conveyer belt being arranged to travel in the same direction as the uppermost conveyer belt in the array.
9. A conveyer freezer according to any one of the preceding claims wherein an product collector conveyer belt is provided that conveys product through the outlet out of the container, the product feeder Conveyer belt being arranged to travel in the same direction as the lowermost conveyer belt in the array.
10. A conveyer freezer according to any one of the preceding claims wherein the support structure comprises one or more frame members upon which are mounted the conveyer belts.
11. A conveyer freezer according to claim 3 and any claim dependent thereon wherein the support structure is provided with means enabling it to be moved in and out of the container.
12. A conveyer freezer according to claim 11 wherein the means enabling the support structure to be moved in and out of the container comprises wheels or rollers or a combination thereof.
13. A conveyer freezer according to claim 12 wherein the support structure is provided with a plurality of wheels and two or more substantially parallel tracks are provided on a floor or base of the container along which the wheels can travel. * S
14. A conveyer freezer according to claim 13 further comprising external tracks which in use are disposed externally of the container and are connected to tracks within the container so as to enable the support structure and array of conveyer belts to be moved out of the container.
15. A conveyer freezer according to any one of the preceding claims wherein an ancillary cooling means is disposed within the container.
16, A conveyer freezer according to claim 13 wherein the ancillary cooling means comprises means for blowing a stream of chilled air over the product.
17. A conveyer freezer according to claim 16 wherein the ancillary cooling means comprises one or more air knives.
18. A conveyer freezer according to claim 17 wherein an air knife is provided for directing chilled air onto products on at least the uppermost conveyer belt.
19. A conveyer freezer according to claim 18 wherein air knives are provided for directing chilled air onto products on the uppermost three conveyer belts.
20. A conveyer freezer substantially as described herein with reference to the accompanying drawings.
21. Apparatus comprising a support structure carrying an array of at least four vertically stacked conveyer belts as defined in any one of the preceding claims.
22. A method of freezing or chilling a product (e.g. a food product), which method comprises passing the product though the inlet of a conveyer freezer as defined in any one of claims 1 to 20 and conveying the product along the path through the freezer to the outlet over a period of time sufficient to bring about freezing or chilling of the product.
23. A method according to claim 22 wherein the product is selected from foods :.: of a particle size in the range from 4 to 50 mm in diameter.*
24. A method according to claim 23 or claim 24 wherein the product is selected from whole vegetables; chopped or cut vegetables; whole fruits; chopped or sliced fruits; and seafood. **S * * S a,