IES67784B2

IES67784B2 - Thermal treatment of food products

Info

Publication number: IES67784B2
Authority: IE
Inventors: Nicholas Anthony Jackman; Oliver O'toole
Original assignee: Nicholas Anthony Jackman
Priority date: 1994-06-10
Filing date: 1995-06-12
Publication date: 1996-04-17
Also published as: IE950427A1; IE74240B1

Abstract

Apparatus (1) for the thermal treatment of food products has four thermal zones (2, 3, 4, 5) using different types of conditioned air flow to treat the products - either cooking or cooling the products. A conveyer 10 delivers products through a tunnel (8) extending through the thermal zones (2, 3, 4, 5) which are arranged in series. The example shown has a first heater (2) in which a contraflow air stream is directed over the products. Then in a second heater (3), air is circulated within the second heater (3) and directed towards opposite sides of the products on the conveyor (10). Downstream of the second heater (3) in a cooker, a collimated hot air stream is directed at relatively high velocity towards the conveyor (10). Finally, in a final heater (5), an air stream is directed over food products on the conveyor (10), the air stream travelling in the same direction as the food products.

Description

Thermal Treafc»ent_qf -Food Products This invention relates to an apparatus and process for the thermal treatment of food products, and in particular cooking and/or chilling food products.

According to the invention, there is provided an apparatus for the thermal treatment of a food product, the apparatus comprising at least three thermal zones, a tunnel extending through the thermal zones, the tunnel having an inlet and an outlet, a conveyor mounted in the tunnel for delivering a product between the inlet and the outlet, the conveyor passing through each thermal zone between the inlet and the outlet, the thermal zones comprising a main thermal zone, a pre-treatment zone upstream of the main thermal sone and an equalising sone downstream of the main thermal sone, the main thermal sone having means for thermally conditioning air and delivering the conditioned air to an air distributor having a plurality of tubular outlets above and below the conveyor, the outlets extending across the width of the conveyor for directing a collimated air stream at relatively high velocity towards the conveyor for heating or cooling food products carried on the conveyor, means for delivering air from the main thermal zone through the pre-treatment sone between a product outlet and a product inlet of the ore-treatment sone in contraflow to the direction of travel of products through the pre-treatment zone and means for delivering air from the main thermal zone through the equalising sone between a product inlet and a product outlet of the equalising zone in the same direction as the direction of travel of products through the equalising sone, and a fourth thermal sone, namely, a recirculating sone, the recirculating zone having means for circulating air within the recirculating zone and directing an airstream towards the conveyor. 77c4 ·· 2 In another embodiment, the recirculating zone is positioned upstream of the main thermal zone.

In a further embodiment, the recirculating sone has a fan with an air inlet and an air outlet, the air inlet communicating with an interior of the recirculating sone and the air outlet communicating with air manifolds extending above and below the conveyor, a diffuser plate at an outlet of each manifold facing the conveyor and extending across the width of the conveyor, each diffuser plate having a number of spaced-apart air outlet openings for directing an airstream towards the conveyor.

In another embodiment, a restriction is provided in one or both of the pre-treatment sone and the equalising sone, the restriction being provided within the tunnel to narrow the tunnel intermediate an air inlet and an air outlet to increase the speed of air flow within the tunnel as it is delivered between the air inlet and air outlet.

In a further embodiment, means is provided for injecting air into the pre-treatment sone for combining with air from the main thermal zone to cause turbulent air flow within the pre-treatment sone.

Preferably, a heat exchanger is provided in an air feed duct for the injected air, the injected air being delivered through a secondary side of the heat exchanger prior to delivery to the pre~treatment sone, an air exhaust duct from the equalising sone connected to a primary side of the heat exchanger for heat transfer between the exhaust air and. the injected air.

In a further embodiment of the invention, there is provided a method for the thermal treatment of a food product using the apparatus as claimed in any preceding claim including the steps of delivering the food product on a conveyor to a tunnel extending through a number of thermal zones arranged in series, in a pre-treatment sone directing an air stream in contraflow over the food product, in a recirculating zone circulating air within the recirculating zone and directing air towards opposite sides of the food product on the conveyor, in a main thermal zone directing a collimated conditioned air stream at relatively high velocity towards the food product on the conveyor, and in an equalising zone directing an air stream over the food product, the air stream travelling in the same direction as the food product through the equalising zone.

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 a schematic, partially sectioned elevational view of a cooking apparatus according to the invention.; Fig. 2 is a diagrammatic, sectional elevational view of portion of the cooker apparatus; Fig. 3 is a diagrammatic, end elevational view of the cooker portion shown in Fig. 2; and Fig. 4 is an elevational view of another cooker apparatus.

Referring to the drawings, and initially to Figs. 1 to 3 thereof, there is illustrated a cooker apparatus according to the invention and indicated generally by the reference assigned the same reference numerals. In this case, however, a second cooker 52 is provided and a temperature equalising zone 53 is provided intermediate the two cookers 4, 52. Within the temperature equalising zone 53, a fan and diffuser plate assembly similar to that shown in Figs. 2 and 3 is provided for circulation of air within the temperature equalising zone 53.

Further, in each of the first heater 2 and final heater 5, a restriction 55 is provided within the tunnel 8 intermediate a fluid inlet 56, 57 and fluid outlet 58, 59 to increase the speed of air flow through the tunnel 8 between the fluid inlet and outlet. The restriction is formed by a baffle plate which extends down from a roof of the tunnel 8 and is spaced closely above the conveyor 10 to provide a narrow air passage 60, 61.

It will be appreciated that similar apparatus may be provided for chilling food products, in this case, cooling means is provided instead of the burners in the cooker sones described above.

It will be appreciated that the invention allows the thermal treatment of food products in an efficient manner. Optimum heat transfer is achieved and a high quality product produced by using a range of airflows as described herein to treat the product in a number of stages.

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

Claims

1. An apparatus for the thermal treatment of a food product, the apparatus comprising at least three thermal zones, a tunnel extending through the thermal zones, the tunnel having an inlet and an outlet, a conveyor mounted in the tunnel for delivering a product between the inlet and the outlet, the conveyor passing through each thermal zone between the inlet and the outlet, the thermal sones comprising a main thermal zone, a pre-treatment zone upstream of the main thermal zone and an equalizing zone downstream of the main thermal sone, the main thermal zone having means for thermally conditioning air and delivering the conditioned air to an air distributor having a plurality of tubular outlets above and below the conveyor, the outlets extending across the width of the conveyor for directing a collimated air stream at relatively high velocity towards the conveyor for heating or cooling food products carried on the conveyor, means for delivering air from the main thermal sone through the pre-treatment sone between a product outlet and a product inlet of the pre-treatment sone in contraflow to the direction of travel of products through the pre-treatment zone and means for delivering air from the main thermal zone through the equalizing sone between a product inlet and a product outlet of the equalizing zone in the same direction as the direction of travel of products through the equalising zone, and a fourth thermal sone, namely, a recirculating sone, the recirculating zone having means for circulating air within the recirculating sone and directing an airstream towards the conveyor.

2. Apparatus as claimed in claim 1 wherein the recirculating zone is positioned upstream of the main thermal zone, and preferably the recirculating zone has a fan with an air inlet and an air outlet, the air inlet communicating with an interior of the recirculating zone and the air outlet communicating with air manifolds extending above and below the conveyor, a diffuser plate at an outlet of each manifold facing the conveyor and extending across the width of the conveyor, each diffuser plate having a number of spaced-apart air outlet openings for directing an airstream towards the conveyor, and preferably a restriction is provided in one or both of the pre-treatment zone and the equalizing zone, the restriction being provided within the tunnel to narrow the tunnel intermediate an air inlet and an air outlet to increase the speed of air flow within the tunnel as it is delivered between the air inlet and air outlet,and preferably means is provided for injecting air into the pre-treatment zone for combining with air from the main thermal zone to cause turbulent air flow within the pre-treatment sone, and preferably a heat exchanger is provided in an air feed duct for the injected air, the injected air being delivered through a secondary side of the heat exchanger prior to delivery to the pre-treatment zone, an air exhaust duct from the equalizing zone connected to a primary side of the heat exchanger for heat transfer between the exhaust air and the injected air. <

3. . An apparatus substantially as hereinbefore described with reference to the accompanying drawings

4. A method for the thermal treatment of a food product using the apparatus as claimed in any preceding claim including the steps of delivering the food product on a conveyor through a tunnel extending through a number of thermal zones arranged in series, in a pretreatment zone directing an air stream in contraflow

5. Over the food product, in a recirculating zone circulating air within the recirculating zone and directing air towards opposite sides of the food product on the conveyor, in a main thermal zone directing a collimated conditioned air stream at

6. 10 relatively high velocity towards the food product on the conveyor, and in an equalizing zone directing an air stream over the food product, the air stream travelling in the same direction as the food product through the equalizing zone.

7. 15 5. A method for the thermal treatment of a food product substantially as hereinbefore described with reference to the accompanying drawings.