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US 6,914,226 B2Granted
Oven for heating a product with RF energy
AssigneeComdel, Inc.
InventorSteven Thomas Ottaway
Life of this patent
Estimating the term…
Abstract
RF energy provided by electrodes positioned between a product is used to heat a product that exhibits a variable impedance during the heating process. As the product's impedance changes during the heating process, RF heating system impedance can be maintained constant by adjusting the distance between the electrodes, adjusting the impedance of a variable impedance device connected between the RF power source and an electrode, or a combination of electrode distance adjustment and impedance adjustment of the variable impedance device. The system is particularly applicable to the heating or pasteurization of bulk food products with multiple heating zones.
Claims16
An oven for heating a product, the oven comprising:
- a conveyor apparatus to convey the product through the oven;
- one or more first electrodes;
- one or more second electrodes, the one or more second electrodes disposed relative to the one or more first electrodes to form a heating path between the one or more first electrodes and the one or more second electrodes through which the product is conveyed on the conveyor apparatus;
- one or more variable impedance devices, each of the one or more variable impedance devices having an adjustable impedance, and an input and an output, the output of an each one of the one or more variable impedance devices exclusively connected to at least one of the one or more first electrodes;
- an at least one adjustable length electrode feeder connecting the output of at least one of the one or more variable impedance devices to at least one of either the one or more first or second electrodes, whereby the distance between the at least one of either the one or more first or second electrodes and the product can be adjusted as the impedance of the adjustable length feeder is changed;
- one or more power sources, each of the one or more power sources having an RF power output, the RF power output of each one of the one or more power sources exclusively connected between the input of at least one of the one or more variable. impedance devices and at least one of the one or more second electrodes, the RF power output of each of the one or more power sources supplying RF power with a potential difference between the one or more first electrodes and the one or more second electrodes to radiate a RF energy between the one or more first electrodes and the one or more second electrodes, the RF energy to heat the product as the product is conveyed through the heating path;
- and
- whereby heating of the product is controlled by varying the adjustable impedance of each of the one or more adjustable impedance devices in an each circuit formed by one of the one or more power sources, one of the one or more variable impedance devices or the at least one adjustable length electrode feeder and the one of the one or more variable impedance devices associated with the at least one adjustable length electrode feeder, one or more first electrodes and one or more second electrodes, as the product is conveyed through the heating path.
5 more elements
A conveyor oven having a plurality of heating zones for heating a product with variable impedance, the oven comprising:
- a first conveyor belt;
- a second conveyor belt disposed relative to said first conveyor belt to establish a heating path between the first and second conveyor belts;
- a drive apparatus to drive the first conveyor belt and second conveyor belt whereby the product positioned at a first end of the heating path will be conveyed through the heating path by contact with at least one of the first or second conveyor belts;
- a one or more first electrodes for an each one of the plurality of heating zones, the one or more first electrodes disposed below the surface of the first conveyor belt opposing a surface of the first conveyor belt forming a first boundary of the heating path;
- a one or more second electrodes for the each one of the plurality of heating zones, the one or more second electrodes disposed above the surface of the second conveyor belt opposing a surface of the second conveyor belt forming a second boundary of the heating path;
- a one or more variable impedance devices for the each one of the plurality of heating zones, each one of the one or more variable impedance devices having an adjustable impedance, and an input and an output;
- an adjustable length electrode feeder apparatus connecting the output of an each one of the one or more variable impedance devices to either at least one of the one or more first or second electrodes, whereby the distance between the one or more first and second electrodes can be adjusted as the impedance of the adjustable length feeder is changed;
- and an at least one power source for the each one of the plurality of heating zones, the at least one power source having an RF power output, the RF power output connected between the input of the one or more variable impedance devices for the each one of the plurality of heating zones associated with the at least one power source, and either at least one of the one or more first or second electrodes not connected to the adjustable length feeder apparatus, the RF power output of each of the one or more power sources supplying RF power with a potential difference between the one or more first electrodes and the one or more second electrodes to radiate a RF energy between the one or more first electrodes and the one or more second electrodes, the RF energy to heat the product as the product is conveyed between the one or more first and second electrodes in the each one of the plurality of heating zones;
- whereby the heating of the product in the each one of the plurality of heating zones is controlled by varying the adjustable impedance of each of the one or more variable impedance devices and varying the length of the adjustable length feeder apparatus in an each circuit formed by the at least one power source, the one or more variable impedance devices, the adjustable length electrode feeder apparatus, the one or more first electrodes and the one or more second electrodes associated with the each one of the plurality of heating zones, as the product is conveyed between the one or more first and second electrodes in the each one of the plurality of heating zones.
6 more elements
A method of heating a product in an oven comprising the steps of:
- conveying the product through a heating path in one or more heating zones of the oven;
- subjecting the product to an RF energy as the product is conveyed through the heating path, the RF energy produced by an RF power source and radiated between one or more first electrodes and one or more second electrodes disposed on opposing sides of the product as the product is conveyed through the heating path;
- adjusting the impedance of a circuit formed by the RF power source and the one or more first and second electrodes by a variable impedance means inserted in the circuit as the product is conveyed through the heating path:
- and
- adjusting the impedance of a second circuit formed by the RF power source, one of the variable impedance means, and an adjustable length electrode feeder apparatus attached to one of the one or more first electrodes or one or more of the second electrodes by varying the length of the adjustable length electrode feeder apparatus to vary the distance between the one or more first electrodes or one or more second electrodes and to vary the impedance of the adjustable length feeder.
2 more elements
Dependencies are inferred from the claim text.