GB2090393A - Plate freezers - Google Patents

Abstract

A plate freezer comprising internally cooled freezer plates 1 having peeling means provided by means of which product frozen against a plate surface can be urged to part from that surface, the peeling means having a finger 5 which lies between the frozen product and the surface, an actuator 8 and a boss 6 about which the peeling means can pivot, the peeling means being actuated in respect of each plate as the plate is moved from a freezing position to a discharge position. <IMAGE>

Description

SPECIFICATION Improvements in and relating to plate freezers This invention is concerned with improvements in and relating to plate freezers and more particularly vertical plate freezers.

Vertical plate freezers are known which comprise a plurality of parallel vertical plates in which are passages for cooling fluid, the plates being movable, each relative to its neighbour or neighbours, freezing of product between adjacent plates being effected when those plates are at a first separation or closed condition which is increased to a second separation or open condition in order to remove the product from between those plates when frozen. By virtue of the freezing of the product, it will become bonded to the plates between which it has been frozen and this bond has to be broken. This can be achieved simply by brute force or by removing the cooling fluid from the plates and by passing a heating fluid through the passages in the plates to thaw out the bond, or by a combination of both.To reduce bonding the plates may be coated with a suitable material such as polytetrafluoroethylene.

However, if the bond is to be broken by force the entire structure and mechanism for parting the plate has to be very robust and substantial energy is required. If the bond is to be broken by thawing there is energy wastage in the heating of the plates and of the product surface. When freezing liquid material, which can be done by pouring the liquid between the plates which form side walls of a container, the thawing of the bond will inevitably involve thawing the surface of the frozen block of liquid and hence loss of product.

It is an object of the present invention to provide an improved plate freezer which uses a different means for breaking the bond.

According to one aspect of this invention a plate freezer comprises a plurality of parallel plates having passages therein for flow of coolant and in respect of the surface of each plate against which product is to be frozen, peeling means having a finger which will extend between that surface and the product and an actuator movable relative to said plate surface to move the finger away from the associated plate surface.

The peeling or stripper means will in effect peel or strip the product from the plate as the plate moves relatively towards the open condition for unloading frozen product.

The finger preferably extends along the full extent of one side of the plate, in the case of a vertical plate freezer that is from the bottom to the top adjacent one vertical edge of the plate. In the case of a vertical plate freezer for freezing liquids the stripper of one plate surface will be formed so that it abuts the stripper of the plate cooperating with the surface of the adjacent plate to form a substantially liquid tight wall extending between those plates when in the closed condition and the other two walls of the container for the liquid to be frozen between those surfaces may be formed by an L-shaped lifting member of which a horizontal limb will form the base, the free end of that limb conforming to the internal surface of the wall defined by the strippers, and the vertical limb the wall opposite the strippers.

In orderthatthe invention may be well understood there will now be described an embodiment thereof, given by way of example only, reference being made to the accompanying drawings in which Figure 1 is a diagrammatic side elevation of a vertical plate freezer with the plates in the closed condition for loading and freezing, Figure 2 is a detail of the freezer of Figure 1 with the plates in the open condition, Figure 3 is a horizontal section of a part of each of four freezer plates in the closed condition, Figure 4 is a horizontal section through two plates of Figure 3 in the open condition and Figure 5 is a horizontal section through a pipe connector for coolant fluid to a plate.

Referring to Figure 1 there is shown a vertical plate freezer comprising a plurality of parallel vertical freezer plates 1 in which are passages for coolant flow. Beneath the plates is a bottom plate 2 which is movable relative to the plates up and down to discharge frozen product and such a freezer is referred to as a bottom discharge vertical plate freezer. To move the plates to the closed condition, a force is applied to an end plate A by any suitable means such as a ram and the end plate transmits the force to the next plate through a suitable abutment (not shown) between those plates and so on. To open the plates after freezing of the product the movable end plate draws away its neighbour by draw bolts 3a.That plate draws its neighbour until no further separation is allowed by the draw bolts 3b at which stage the second plate from the movable end plate separates from the next in line until the draw bolts there between allow no further separation of those two and soon.

In this embodiment the vertical walls between any two adjacent plates which, with those plates and the bottom plate define an open top container, are each formed by a pair of peeling means of strippers 4.

Referring now to Figure 3, each stripper comprises a length of any suitable material such for example as polytetrafluoroethylene which in cross sectiion comprises a finger 5, a boss 6, a closure flange 7 and an actuator 8. In Figure 3 the plates are in the closed condition and in that condition the ends of the flanges 7 abut and by virtue of the root of each of those flanges being inward, relative to the edge of the associated plate, of the line of contact of the boss associated with that flange with the surface of the associated plate, the stripper will be urged to bring the free edge of the finger in contact with the plate surface. Thus there will be contact between the flanges of the strippers forming the wall and contact between the fingers and the plates. Also the ends of the strippers will be adjacent the base plate.In the closed condition of the plates liquid can be poured into each open topped container thus formed and if there is not absolute liquid tightness at the regions referred to, flash freezing of the liquid will seal any regions where good sealing is not achieved.

When freezing is complete, the plates are progressively drawn toward the open condition as ex plained. Referring now to Figure 4 the draw bolts 3b extend through the actuators 8 and as a head 9a of the righthand draw bolt approaches plate 1a (opening action being rightwards in that Figure) it engages the actuator on the same side of the plate as the head, causing the stripper to try to turn (anticlockwise in this instance). When the plate la begins to move under the action of the bolt head 9a the combined effect of the finger and head is to peel the plate off the block of product, there being a small degree of flexibility in the plate.

The same action is effected by the relative approach of the next plate 1b to the head 9b of the associated draw bolt.

When the plates reclose the ends of the flanges 7a, 7b meet and as explained above, rotate the respective strippers back to the condition shown in Figure 3. Figure 2 shows diagrammatically two plates in open condition.

The strippers are dimensioned so that the dimension y is greater than the dimension x and plate spacing in the plate open condition being approximately V2 greaterthan plate spacing in the closed condition the dimensions ofthe strippers are chosen to give a movement at the fingertips of about 1/8" relative to the associated plate surface.

A particular advantage of the construction described is that the plate separation in the closed condition is set by the strippers as opposed to flanges welded to the plates. Thereby for different thicknesses of product standard plates can be used and appropriate strippers provided. For any given freezertherefore different product can be handled by changing the strippers.

In the case of a freezer to be discharged from the top, the base plate may be omitted as well as one of the vertical walls defined by a pair of cooperating strippers between adjacent plates. In their place an L-shaped unloader is provided between each pair of adjacent plates the horizontal limb defining the base of the open top container and the vertical limb, a vertical wall.

It may be desirable to coat the surface of each stripper exposed to the product such as with in order to prevent or reduce attachment of the strippers to the product.

Turning now to Figure 5, there is shown a plate 1 c, draw bolt 3c and stripper 4c all as already described.

To couple a coolant fluid pipe to a freezer plate there is welded to the plate a flange 12 having one or more passages 13 each in register with an entry or exit of a plate coolant passage. The flange 12 has outwardly turned lips 14 engaged by inwardly turned lips 15 of a clamp 16 positioned along the flange to register a pipe end 17 with a passage 13. The pipe is given an external shape suitable for engagement by a suitable tool so that the pipe which is threaded into the clamp 16 may be tightened to thrust the pipe end into engagement with the base of a suitable recess 19 in the flange where a gasket may be positioned.

Claims (10)

1. A plate freezer comprising a plurality of para llel plates each having a passage therein for flow of coolant and, in respect of the surface of each plate against which product is to be frozen, peeling means comprising a finger which will lie between that surface and product to be frozen and an actuator movable relative to that surface to urge the finger away from that surface.

2. A plate freezer according to claim 1 in which each peeling means includes a boss which will bear on the surface and about which the peeling means is pivotable by the actuator.

3. A plate freezer according to claim 2 in which draw bolts extend through pairs of plates and through the actuators associated with oppositely directed surfaces of the pair of plates, the draw bolts upon movement of the plates toward the second position engaging the actuators to urge the peeling means to pivot about their respective bosses.

4. A plate freezer according to claim 3 in which the draw bolts effect the progressive separation of the plates.

5. A plate freezer according to claim 3 or claim 4 in which the peeling means includes a flange projecting in the opposite sense to that of the boss and offset relative to the boss so that pressure on the free edge of the flange toward the surface will urge the peeling means to pivot about the boss and carry the finger toward the surface.

6. A plate freezer according to claim 5 in which, in the first position of the plates, the flange of the peeling means associated with the surface of one plate abuts the flange of the peeling means of the adjacent surface of the adjacent plate to urge the fingers of those respective peeling means against their respective surfaces.

7. - A plate freezer according to claim 6 in which the peeling means extend along at least one edge of each surface and together form a barrier extending between the adjacent surfaces of the adjacent plates, being a wall of an enclosure in part also defined by the adjacent surfaces into which product can be fed for freezing.

8. A plate freezer according to claim 7 in which peeling means extend also along the opposite edge of each surface and form a second barrier, the surfaces and barriers together with a base plate defining the enclosure.

9. A plate freezer according to claim 7 in which a barrier along the opposite edge of each surface and a base for the enclose is formed by an L-section member by means of which frozen product can be removed from between the adjacent surfaces.

10. A plate freezer substantially as herein described with reference to the accompanying drawings.