A METHOD FOR FREEZING GOODS BROUGHT TO A REGIONAL COLD STORE AND A SYSTEM FOR USE WITH THE METHOD

Abstract: It is common practice that meat products from several slaughterhouses are transported to a central or regional cold store plant, in which the products are freezed at some -40<o>C and thereafter transferred to a cold storage at some -25<o>C. Particularly for pork it is important that the freezing be effected rapidly after the slaughtering, and this has been obtained merely by a reasonably rapid transportation to the cold store. However, with the invention use is made of special transport vans (2) designed as real freezing units, in which the air is refrigerated to some -40<o>C, and at the slaughterhouse the products are loaded in a non-frozen state into such a van, whereby at least a part of the freezing action is effected during the transportation. The freezing may be initiated almost immediately after the slaughtering. The freezing vans constitute a part of the entire freezing capacity of the cold store, and the use of the vans implies both a better utilization of the capacity and a possibility of an enlarged radius of action of the cold store plant, as the duration of the transport will now be insignificant for the initiation of the freezing. The cooling capacity of the freezing vans should be some 2-5 times as high as for usual refrigerated vans.

Description: A method for freezing goods brought to a regional cold store and a system for use with the method. The present invention relates to a method for handling and transportation of foodstuffs, especially pork, which from a production locality, i.e. especially a slaughterhouse or meat cutting plant are to be brought to a cold store. The production in any slaughterhouse can be rather fluctuating, and notably the sale may fluctuate, so that a need naturally appears to operate with a buffer stock of products, which should be kept in a frozen condition. The single slaughterhouses may therefore have a freezing storage, but it common that such a storage is dimensioned with a relatively mo ' dest capacity since it has proven economically more advantageous that several or many slaughterhouses use a central or. regional cold store plant having a very large capacity. Hereby it is possible to operate w th a capacity which certainly is large, but not nearly as large as the combined required freezing storage capacity for all the single slaughterhouses, inasfar as the storage need fluctuates constantly in a manner which is not the same from one slaughterhouse to another. On this background a well-established practice has developed according to which the single slaughterhouses notify the regional cold store plant that at a given time - usually with a short notice - a shipment of goods for freezing will be delivered, or that an already frozen quantity must be delivered for transportation away from the storage p lant . It is especially essential for pork that the freezing of the meat take place quite quickly after the slaughtering and cutting, and therefore it is necessary that the store plant is notified of the time " of delivery of the meat, which is usually del vered in a refrigerat¬ ing lorry after up to 2-3 hours of driving. The cold store plant should then be capable of effectuating a proper freezing of the meat immediately following the arrival, which implies in practice a quick freezing at appro imately -40 C, whereafter the goods can be transferred to a cold storate with a temperature of about -25°C. The rapid freezing is essential notably for pork, as substantial amounts of meat juice may otherwise have time to extrude, and by the freezing process it is thereby an aim that an iceshell is formed as quickly as possible around the goods, for prohibiting further juice extruding. The goods may thereafter be transferred to the cold storage without being frozen -tb the .core at the extremely low freezing temperature, provided only that the outer freezing shell has been formed, and that a core temperature of approximately -8°C has been attained. It has appeared specifically for pork that the freezing should be effectuated quite quickly after the delivery of the meat goods from the slaughterhouses, wherefore the regional freezing plants must give igh priority to shipments of pork, with regard to the use of the high effect freezing equipment, the capacity of which for natural reasons being considerably smaller than the cold storage capacity as a whole. The transportation of the meat from the slaughter- house to the freezing plant can approp iately take place in usual refrigerating vans, in which there is a temperature only slightly above freezing level, so that the meat is already somewhat refrigerated before being handed over to the freezing plant. For the time it takes to form the said ice shell around the goods, however, it is not too important whether the goods have been cooled down the few centigrades as achievable during a transportation ti e of up to a few hours. However, by the invention it has been recognized that even such few hours of transportation can be decisive for whether the meat is delivered timely enough to become frozen before the extrusion of juice has become so pronounced that the meat quality has already been commercially considerably reduced. It has been found that this may be a question of few hours only, and on this background it would be recommendab le that the single slaughterhouses expand their freezing capacity to a reasonably increased minimum. The invention, however, provides for an entirely different solution, namely by proposing that the single slaughterhouses should not have to increase their freezing capacity, while on the other hand care is taken that the vans which «.c. ar*ry the meat to the cold store plant are not just ordinary lorries or refrigerated vans, but are specialized "freezing vans", in which the temperature is considerably lower than in ordinary "cooling vans", and which are equipped such that during the transportation the goods may be subjected to a real freezing effect or influence ins de the van box. Hereby the freezing treatment may be initiated immediately by the loading in of the goods into the freezing van, i.e. practically without any delay at all. By the arrival at the cold store plant the goods are loaded into the stationary quick freezing system of the plant, where they may remain during the required, now reduced time period until the freezing is completed. Alternatively the goods may be loaded directly into the cold storage if they, during the transportation, have become entirely frozen. The invention shows two essential main advantages, viz. partly that the freezing can be initiated with a mini.mum of delay, and partly that the advantage of using large regional cold store plants wi ll be increased due to the fact that the radius of act on of such a plant will be increased, because it will now be less important if the time of transportation to the plant is increased considerably. In practice the invention manifests itself in that a part of the freezing capacity of the cold store plant is laid out in mobile units, or, respectively, that the capacity is increased by means of the mobi le units. These will to a high degree contribute to a relative increase of the total capacity o r to the utilizability of a given total capacity, already because the freezing, if required, may be continued in a freezing van upon its arrival at the cold store plant, if there is no immediate vacancy in the stationary freezing section thereof. Thus, although mobile units with their associated advantages are concerned, these units are optionally usable directly as a supplement to the stationary freezing equipment. Moreover the units are usable in the way that they may be parked at the production site and act as a receiving freezing storage for products, which arrive in a more. or less regular flow with time intervals sufficiently long to condition a need for the van door to be repeatedly opened and closed for the introduction of the products, singular or groupwise, for which reason it is preferred to make use of a roll-door. When the van is filled the related !'freezing storage" may be driven to the central cold store plant, in w ich it may be considered that the products as firstly loaded into the van will already be frozen more than the lastly loaded products. It is to be noted that the term "freezing" is a technically well defined expression referring to a strong cooling or chilling, whereby a given product is cooled, by intensive oversweeping with a freezing medium, normally air, from a temperature slightly above 0°C to a core temperature of between -12 C and -30 C during a certain period of time, which is for meat about 30-36 hours. Hereby extra cold energy should be supplied for the freezing, i.e. for the phase shift between non- frozen and frozen condition of the product; hereby high amounts of heat should be removed, this situation being highly different from "cooling". With the invention the relatively short duration of the presence of the products in the mobile-freezing unit will not amount to an initiated general freezing, but owing to the fact that the unit is designed for effecting a "freezing" the already dicsussed advantage of the products being rapidly "shell-frozen" will be obtained, and this is very i mportant . In practice the mobi le unit should be equipped with a refrigeration system having a cooling capacity which is of the magnitude 2-4 times ' the capacity as usual for cefπ " ge ' rated vans. The invention even comprises the said mobile unit or units, i.e. freezing vans designed particularly for being usable as freezing units, this requiring a forced circulation of freezing air having a temperature of some -40 C. In the drawing such a unit is shown, Fig. 1 being a schematic lateral ew, partly in section, while Fig. 2 is a cross sectional view of the freezing box of the unit, and Fig. 3 is a graphic representation of a freezing course. The van shown has a well heat insulated freezing box 2 having at its front end a refrigeration system 4, which is designed to have a considerably higher cooling capacity than normal for refrigerated vans, inasfar as the temperature inside the box 2 should be considerably lower than normally, viz. down to some -40 C. Thus, the temperature should be kept low, but additionally the air should be brought to flow rather strongly through the product piles 6 as deposited on the freezing box. It is customary that products to be frozen are piled w th horizontal partitions which are air permeable in the horizontal direction, e.g. constituted by corrugated plates or sandwich plates having flow-through channels designated 8, and such piles should be insertable into the box 2 and be freezable therein just as they would otherwise be insertable and freezable in a stationary freezing system. Inside the box 2 is provided a thin intermediate ceiling 10, which stretches from the front end of the box 2 to adjacent the rear end thereof, such that a flat channel 12 is formed between the intermediate ceiling 10 and the ceiling of the freezing box. At its front this channel is connected to the refrigeration system 4 through a fan 14, while at its rear end tffe channel is in open connection with the underlying cargo compartment of the box. At its front th i s ,compartment is connected with the refrigeration system 4 through an opening 16, such that the air, as shown by arrows, may circulate rearwardly through the cargo compartment in the box 2, forwardly -through the channel 12, and down through the refrigeration system 4. The opening 16 may be shaped as a row of slot openings distributed all over the end surface of the cargo compartment. The fan equipment 14 should be rather heavily designed, such that a strong wind is created rearwardly in the cargo compartment. If the products are not piled fully up to the intermediate ceiling 10 a free flow channel will occur along the underside of th s element, whereby the air flow through the piled products will be weakened. For this reason a number of so-called tape curtains 18 are suspended in the ceiling element 10 so as to be lowerable to a posi ion just above the top sides of the piles, whereby the said free flow channel will be broken. For a van box 2 of usual size, i.e. for a 40 feet container, the refrigeration system should have a cooling capacity of at least 20 kW and preferably even 30-40 kW, while for refrigerated vans the usual capacity is some ό-9 kW, in both instances for an evaporation temperature of some -30 C and a condensation temperature of some 45 C. When taking into account that the upper channel 12 does not form part of the effective freezing space the cooling capacity should, generally, amount to some 1/2 - 1 kW per cubic meter of effective freezing space. From the beginning, at ambient temperature, the air temperature should be lowerable to -20 C during some 10-20 minutes. In Fig. 3 the curve A illustrates the progress of the freezing in a unit according to the invention, while the curve B shows the corresponding progress in a regional freezing store plant, in w ich the quite similar course takes place with a delay which may be considerable all according to the time of transportation from the production site. The curves represent the temperature in an arbitrary measuring point in the products, and since the formation of the said freezing shell is initiated and concluded inside the temperature range between 0 C and -2 C it will be noted that particularly this important formation wi ll be promoted considerably. The evaporator part of the refrigeration system is designed for cooling down the circulating air to some -40 C, and the associated condenser is laid out to be cooled partly by the speed wind in a usual manner and partly by a non-illustrated, extra fan equipment of sufficient capacity for being effective during stillstand of the van or the van box, e.g. if it is required, upon arrival to the cold store plant, to wait some time for vacant capacity in the stationary freezing station, as well as dyring loading on the production site. The van is built as a semi-trailer, whereby van box 2 with the refrigeration system 4 may be parked at the production site or at the entrance to the stationary freezing system, while the tractor part may be used for transportation of other cooling or freezing boxes. Thus, the complete mobile system may suitably comprise a plurality of freezing van boxes and a lower number of traction units, whereby a high capacity can be achieved in an economical manner. For a fully economical uti lization of the capacity of the single freezing van boxes these should of course be designed so as to be able to hold the highest possible cargo load in the space which is left undei— neath the upper channel 12. This implies that the height of this channel should be minimized optimally, but also that the- height of the- cargo piles should be optimized. In practice, however, there are some limits for the piling height of palletized butchery goods or other goods, because the pressure on the lowermost goods of a high pile may be unacceptably high; if the pi ling height as available in the box 2 is igher than the allowable piling height, then care may be aken to modify the box by a special mounting for carrying both a lower and an upper layer of cargo piles, e.g. with the use of carrier railings at an intermediate height. The channel space 12 may be established otherwise than in the manner shown; the width of the channel may be smaller than the width of the box, and the channel may be arranged on the top of the box or generally outside the box.

Claims: C LAI MS 1. A method of freezing goods, w ich are.transported in vans from a loading area to a regional cold store plant in order to be frozen and then stored in a cold storage, characterized that in the loading area the goods in a non-frozen state are loaded into a van or van box operating as a freezer unit, and that at least a part of the freezing action is effected during the transportation to the cold store plant, where the goods, if required, are loaded into the stationary freezing section of the cold store unit for further freezing. 2. A system for use with the method according to claim 1, comprising a stationary freezing section in a regional cold store plant, characterized in that it additionally comprises one or more mobi le, freezing units in the form of van freezing boxes having associated refrigeration systems designed to produce a circulating air flow in the box with a temperature below -30 C, the cooling capacity of the refrigeration systems being at least 1/2 - 1 kW per cubic meter of effective freezing space. 3. A system according to claim 2, characterized in that each freezing box is designed with an intermediate ceiling stretching from the front end of the box rearwardly to adjacent the rear end thereof, the refrigeration system or an associated fan system being operable to circulate the air through the refrigeration system and the two channels as formed above and beneath the intermediate ceiling, respectively. 4. A system according to claim 3, characterized in that transverse hoist curtains are suspended underneath the intermediate seiling.

Inventors: PLAGBORG KAJ, PLAGBORG, KAJ
Applicants: PLAGBORG KAJ, PLAGBORG, KAJ
Application year: 1986
Main classification: B60P3
IPC codes: B60P3