Introduction

This invention relates to a chiller, and in particular to chiller for cooling food products prior to packaging o freezing.

Statements of Invention

According to the invention there is provided a chille apparatus comprising at least two continuous in-line coolin sections for reception of a product conveyor for delivery o a product to be chilled through each section in turn an regulating means for independently regulating the chillin environment in each section to achieve a controlled reductio of product temperature in a number of stages, at least some o the cooling sections having a cooling fluid inlet and cooling fluid outlet, the cooling fluid being delivere between the cooling fluid inlet and cooling fluid outlet t cool products passed through the section.

In a preferred embodiment the regulating means is operable t control the temperature and the speed of the cooling flui relative to the product to regulate the cooling of product

passed through the section.

In another embodiment the apparatus includes a main chill section and a prechill section upstream of the main chill section.

Preferably the regulating means for the prechill section is arranged to deliver cooling fluid in contraflow to the direction of travel of products through the prechill section. Ideally the regulating means for the main chill section is arranged to direct cooling fluid at a relatively high velocity at products passed through the main chill section.

In another embodiment two main chill sections are provided. The two main chill sections are mounted adjacent each other. Alternatively, an intermediate temperature equalising section is provided between the two main chill sections.

In a further embodiment each main chill section has a pair of spaced-apart cooling fluid inlets for direction of cooling fluid streams at opposite sides of products.

Preferably, the regulating means includes means for regulating the relative amounts of cooling fluid directed to each cooling fluid inlet.

In a preferred embodiment a cooling fluid distributor i provided at each cooling fluid inlet in each main chil section for even cooling fluid delivery towards the products Preferably, wherein the distributor has a plurality of spaced apart discharge holes.

Conveniently the distributor is formed by a matrix of spaced apart tubes.

In another embodiment the regulating means includes means discharge the cooling fluid from the cooling fluid inlet o each main chill section at a speed in the range 0-1400 metre per minute. Preferably, said means is adjustable.

In a further embodiment the regulating means includes mea to adjust the quantity of cooling fluid delivered to ea section.

In another embodiment the regulating means includes contr means to sense the temperature of cooling fluid delivered each section and to adjust the quantity of cooling flu delivered to each section to maintain the temperature with each section within pre-set desirable limits.

In a further embodiment the main chill section includes mea for chilling the cooling fluid. Preferably, the cooling flu for each main chill sections is independently chilled.

In a particularly preferred embodiment the cooling fluid is air.

In another embodiment the pre-chill section has an ambient air inlet, and the regulating means includes means for mixing ambient air with cooling fluid extracted from the main chill section for delivery to the prechill section.

Preferably, the regulating means includes means to control the supply of ambient air to the ambient air inlet to control the temperature of cooling fluid delivered through the tunnel in the pre-chill section.

Advantageously the cooling fluid outlet of the prechill section communicates with the main chill section for recirculation of cooling fluid to the main chill section.

In a preferred embodiment a venting section is provided upstream of the pre-chill section, the venting section having a cooling fluid inlet and a cooling fluid outlet, and a fan for delivery of cooling fluid between the cooling fluid inlet and cooling fluid outlet. Preferably, the cooling fluid outlet is formed by a pair of spaced-apart cooling fluid outlet ducts at opposite sides of the venting section.

Conveniently, the regulating means includes baffles in eac duct to control cooling fluid flow through the ventin section.

In another embodiment the fan is mounted downstream of th ducts to draw air through the venting section between th cooling fluid inlet and cooling fluid outlet.

Preferably, cooling fluid is delivered in a contraflo direction to products passed through the venting section.

Ideally, cooling fluid discharged from the fan is recycle through a main chill section.

In another embodiment a post-chill section is mounte downstream of the main chill section, the post-chill sectio comprising having a cooling fluid inlet and a cooling flui outlet, and means to circulate cooling fluid between th cooling fluid inlet and cooling fluid outlet.

Preferably, a cooling fluid outlet duct is mounted at one en of the post-chill section and the regulating means comprise baffle means in the duct to control cooling fluid flow throug the post-chill section.

In another embodiment cooling fluid is delivered through th post-chill section in the same direction as products ar

delivered through the post-chill section.

In a further embodiment the cooling fluid inlet is connected to a main chill section.

Preferably, the cooling fluid outlet is connected to a main chill section for recirculation of cooling fluid.

In a preferred embodiment each section includes a tunnel for receiving a conveyor along which products to be chilled are led.

In another embodiment the apparatus includes a conveyor extending through the sections of the apparatus.

Detailed Description of the Invention

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings in which:-

Fig. 1 is an elevational view of a multi-step chiller apparatus according to the invention;

Fig. 2 is a schematic partially cut-away elevational view of portion of the chiller apparatus?

Fig. 3 is a schematic sectional elevational view of another portion of the chiller apparatus;

Fig. 4 is a schematic partially sectioned elevationa view of a further portion of the chiller apparatus;

Fig. 5 is a schematic illustration of another chille according to a second embodiment of the invention;

Fig. 6 is a schematic illustration of another chille apparatus according to a third embodiment of th invention; and

Fig. 7 is a schematic illustration of a still furthe chiller apparatus according to a fourth embodiment of th invention.

Referring to the drawings, and initially to Figs. 1 to thereof, there is illustrated a multi-stage chiller apparatu according to the invention indicated generally by th reference numeral 1. A chiller apparatus 1 is of modula construction comprising a number of in-line cooling sections namely a venting section 2, a pre-chill section 3, a pair o main chill sections 4,5 with an intermediate temperatur equalising section 6 and a post-chill section 7 respectivel arranged in series. A tunnel 8 passes through each of th

sections 2, 3, 4, 5, 6, 7 for delivery of a product through each section in turn for chilling. A conveyor 9 extends through the tunnel 8 to deliver a product through the tunnel 8, the conveyor 9 having an inlet end 10 and an outlet end 11. Means is provided in each of sections 2, 3, 4, 5 and 7 for delivering cooling air through the tunnel 8 to cool products delivered through the tunnel 8 on the conveyor 9.

Referring in particular to Fig. 2, the vent section 2 and pre¬ chill section 3 are shown in more detail. The vent section 2 is of modular construction comprising a frame 12 supporting portion of the tunnel 8 through which the conveyor 9 passes. An air inlet 13 is provided at one end of the tunnel section and an air outlet is provided at the other end of the tunnel section in this case being formed by a pair of spaced-apart ducts, namely an upper duct 16 at a top of the tunnel 8 above the conveyor 9 and a lower duct 17 at a lower end of the tunnel 8 below the conveyor 9. A fan 18 is mounted downstream of the ducts 16, 17 to draw air through the tunnel 6 in the venting section 2. The air is drawn through a grease trap 20 mounted between the ducts 16, 17 and the fan 18. It will be noted that air flow, indicated by the arrows, is contraflow to the direction of travel of products along the conveyor 7. The top duct 16 allows extraction of air over the product while the bottom duct 17 allows air to be pulled evenly along the tunnel 8, maximising air contact with the product for cooling. Baffles (not shown) are incorporated in the ducts 16, 17 to

allow air balance in the tunnel 6. It will be noted that th fan 18 speed is adjustable to regulate the quantity of ai drawn through the venting section 2. The tunnel 8 is formed b an insulated cover 22 mounted on the top of the frame 12 an a drip tray 23 mounted on the frame 12 underneath the conveyo 7 with interconnecting sidewalls. A temperature sensor 24 i mounted within the tunnel 8 to sense the air temperature, thi is connected to a PLC in the controls for the chille apparatus 1.

The pre-chill section 3 is also of modular construction an similarly to the venting zone 2 comprises a frame 25 carryin portion of the tunnel 8. An air inlet manifold 26 is mounte above the tunnel 8 and is supplied with fresh filtered ambien air through an air inlet duct 27. With the aid of air baffle (not shown) air is emitted through a number of spaced-apar slots 28 from the manifold 26 into the tunnel 8 and directe at products being carried along the conveyor 9. An air outle of the pre-chill section 3 connects directly with the ai inlet 13 of the venting section 2 and the fan 18 draws ai through both the pre-chill section 3 and venting section 2 It will be noted that the air stream, indicated by the arrows is contraflow to the direction of travel of products on th conveyor 9. It will be noted also that air is drawn into th pre-chill section 3 from the main chill section 4 through th tunnel 8 being combined with the ambient air delivered throug the manifold 26. A baffle (not shown) in the air inlet duc

27 allows the control of air temperature by controlling the proportion of ambient air mixed with cool air from the main chill section 4 to allow for natural fluctuation in ambient air temperature and variations in product type. Thus, conveniently, air can be delivered through the tunnel 8 of the pre-chill section 3 at a preset desirable temperature, for example 15°C with a maximum turbulent flow to ensure good heat transfer from the products on the conveyor 9. Preferably air discharged from the fan 18 is recirculated to the main chill section 4.

Referring in particular to Fig. 3, the cooling sections 4, 5 and 6 are shown in more detail. The main chill sections 4, 5 which are similar are of modular construction and are interconnected by a modular intermediate temperature equalising section 6. The tunnel 8 passes through each section 4, 6, 5 respectively in turn for chilling products delivered through the tunnel 8 on the conveyor 9. Means is provided in each chill section 4, 5 for delivering a relatively high velocity chilled air stream at products passing through the tunnel 8 on the conveyor 9.

Each chill section 4, 5 has an air duct 40 for delivery of air from a fan 45 to a manifold 41 extending above and below the tunnel 8. An air distributor is formed at outlets of each manifold 41 above and below the conveyors for delivery of chilled air at products passing through the tunnel 8. In this

case each air distributor comprises a matrix of spaced-apar tubes 44 which are substantially parallel for direction of stream of chilled air into the tunnel 8 from opposite sides o the tunnel 8 at products on the conveyor 9. Typically the ai is discharged from the tubes 44 at a speed in the range 0-140 linear metres per minute. This allows rapid chilling of th products to be achieved. The fan 45 speed is adjustable t adjust the air speed.

A fan 45 is provided for delivery of air through the air duc 40. An evaporator 46 for chilling air is provided within eac chill section 4, 5 being connected to the fan 45 inlet by tapered- transition piece 47. Preferably two dampers (no shown) are provided within the air duct 40 to both control th flow of air through the air duct 40 and govern the flow of ai through the top and/or bottom tubes 44. Also provided are tw variable dampers 48 at air inlets to the evaporators 46 t enable utilisation of clean ambient air or recirculate chilled air. Thus the relative amounts of cooling ai delivered to each side of the conveyor 9 can readily easily b varied. Thermostats for controlling operation of eac evaporator 46 are provided in the associated manifolds 41.

In this case there is no air circulation through the centra temperature equalising section 8.

Referring to Fig. 4, the post-chill section 7 is shown in more detail. This is generally similar in construction to the venting section 2. The post-chill section 7 is of modular construction comprising a ground-engaging stand alone frame 50 on which the tunnel 8 is formed. The tunnel 8 is formed between an insulated cover 51 mounted at a top of the frame 50 and a drip tray 52 mounted below the conveyor 9. An air outlet duct 54 is provided at one end of the tunnel 8. A fan 55 draws air through the tunnel 8, air outlet duct 54 and a grease filter 57 for recirculation back to the main chiller section 5. Air flow through the tunnel 8 is laminar and uniflow with products delivered through the tunnel 8 on the conveyor 9. A temperature sensor 58 is mounted within the tunnel 8 to sense the air temperature. This is connected to the PLC in the controls for the chiller apparatus 1.

In use, products are delivered to an inlet end 10 of the conveyor 9 and delivered through the tunnel 8 on the conveyor 9. The products first pass through the venting section 2 to remove high humidity waste air and heat by convection from the products which may for example be at a temperature of 72°C on entry to the chiller apparatus 1. As the products pass through the venting section 2, a contraflow air stream passes over and around the products which aids gentle controlled cooling of the products. Downstream of the venting section 2, the products pass through the pre-chill section 3. Within the pre-chill section 3 the products are passed through a cooler

air stream to gently chill the product before subsequen passage through the colder main chiller sections 4, 5. Thi advantageously prevents the products experiencing therma stress on the surface as it subsequently enters the mai chilling section 4. Clean ambient air is introduced and mixe with some chilled air exhausted from the main chill section and the combined air stream is drawn over the products an into the venting section 2. The differential between th product temperature and the cooling air temperature i relatively large at this point resulting in optimum coolin effect and maximum cost efficiency in the use of the naturall existing cooling medium. The quantity of air delivere through the pre-chill section 3 and venting section 2 i controlled by adjusting the speed of the fan 18. Th temperature of the air delivered through the tunnel 8 withi these sections 2, 3 is controlled by regulating the mixing o ambient air with chilled air drawn in from the main chil section 4. In each main chill section 4, 5 air temperature i controlled by the thermostat within the manifold 41 whic regulates the evaporator. Air speed can be controlled b adjusting the fans 45. It will be noted also that the relevan quantities of air delivered to a top surface and an undersid of the conveyor can be adjusted by means of the dampers withi the air duct 40. Thus, for example if products were delivere along the conveyor 9 on trays a larger portion of the ai would be delivered to an underside of the conveyor to promot more even cooling of the product.

By way of example, a product delivered to the conveyor inlet 10 to a temperature of about 72°C, by maintaining the sensed air temperature within the venting section 2 at approximately 15°C will drop 15-20°C in the venting section 2 and approximately 12°C in the pre-chill section 3. Within the main chill section 4 by maintaining an air temperature of approximately 10°C and an air speed in the region of 1400 meters per minute the temperature drop may be 12-15°C. In passing through the intermediate section 6 which is at approximately 5°C the temperature of the product will further drop by about 8°C. With an air temperature of -5°C and an air speed in the region of 600 meters per minute within the main chill section 5 the product temperature will drop a further 15-20°C. It will be noted that the air speed within the second downstream main chill section 5 will generally be lower than the air speed within the main chill section 4 to prevent excessive drying of the product. Typically the air speed within the downstream main chill section 5 is in the order of 600 meters per minute. It will be noted however that the air speeds within each main chill section 4, 5 can be adjusted to meet the requirements of the particular product being cooled. This can be adjusted on a continuous basis for optimum cooling conditions. Within the post-chill section 7 the product is further reduced in temperature by 8-12°C and is typicall discharged at a temperature in the region of 5-8°C.

Downstream of the pre-chill section 3 the products are passe through the main chill section 4. Within the main chil section 4 chilled air delivered through the tubes 44 a relatively high velocity, typically in the range 600-140 meters per minute impinges upon the products on the conveyo 9 to rapidly cool the products. As products discharged fro the first chiller section 4 pass through the intermediat section 6 the temperature of the products is allowed t equalise throughout the products. The products are the delivered through the second main chill section 5 for furthe cooling of the products.

It will be appreciated that the high velocity air within th main chill sections 4, 5 rapidly chills the products. This i advantageous when chilling food products to minimise cel damage and product dehydration and to retain as much of th natural juices of the product as possible.

It will further be appreciated that the tubes 44 ensure a even distribution of air across the tunnel width to ensur that all the products on the conveyor are evenly cooled an are cooled individually. The system is not load related. Th quantity of air delivered to each bank of tubes 44 can b adjusted for optimum cooling of the particular product bein conveyed along the conveyor. The temperature sensors thermostats and fans are all connected to a central contro until for operating the chiller apparatus 1 at any pre-se

desirable condition.

Advantageously, as the chiller is of modular construction, it can be configured to meet any requirements, for example, to match any continuous oven or a spiral freezer, and can be extended with a minimum of disruption to existing production to meet extra capacity or alter cooling methods.

While only two main chill sections with an intervening temperature equalising section have been shown in the disclosed embodiment, any desired number of main chill sections with intermediate temperature equalising sections may be provided. In some cases, for chilling relatively this products, that is less than 12 mm thick, the intermediate temperature equalising section can be dispersed with.

Ideally the tunnel is manufactured of all-welded stainless steel and is available with fully automatic in-place cleaning which ensures complete hygiene to USA or EEC standards.

The control system individually controls each section temperature and air velocities to meet individual product requirements. Air flow is adjustable to ensure no product damage or movement of the product on the conveyor.

It is also envisaged that in some cases the cooling for ai in the upstream main chill sections may be provided by water,

a water cooler replacing the evaporator for the upstream main chill section. This advantageously will allow the running costs to be reduced.

It will be noted that the air is recirculated within the chiller for optimum efficiency and operation.

It will be noted that the apparatus is extremely flexible and the cooling conditions within each section can be adjusted to suit the particular product being cooled. It also allows relatively high speed cooling which is particularly advantageous for matching the chiller to a continuous oven. Energy usage is minimised by using a combination of ambient air and chilled air. The flexibility of the chiller apparatus allows improved product quality control.

Referring now to Fig. 5 there is illustrated another chiller apparatus 70 in which parts similar to the chiller apparatus previously described are assigned the same reference numerals. In this case the apparatus 70 comprises simply a pre-chill section 3 followed by a main chill section 4. As before a conveyor carried products through a tunnel extending through the sections 3, 4.

Referring now to Fig. 6 there is illustrated another chiller apparatus 80 in which parts similar to the chiller apparatus of Figs. 1 to 4 are assigned the same re erence numerals. In

this case the chiller apparatus comprises a pre-chill section 3 with two main chill sections 4, 5. A conveyor delivers products through the sections 3 , 4, 5 in turn as previously described.

Referring now to Fig. 7 another chiller apparatus 90 is shown. Parts similar to the chiller apparatus shown in Figs. 1 to 4 are assigned the same reference numerals. In this case the chiller apparatus 90 comprises in series a pre-chill section 3, a main chill section 4, an intermediate temperature equalising section 6 and a second main chill section 5. Again a conveyor delivers products through a tunnel extending through the sections 3, , 6, 5.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.