Fryer

A continuous fryer that includes a vessel (kettle) (11) through which oil (13) flows in a predetermined direction (12). An upstream end of the kettle (11) is a flow control device (34) that at least aids in maintaining linear flow through the vessel (11) is said predetermined direction (12).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Australian Application No. 2015902715, filed Jul. 9, 2015, the disclosure of which is incorporated by reference herein.

FIELD

The present invention relates to continuous fryers, and more particularly but not exclusively to single-flow and multi-flow continuous atmospheric fryers and vacuum fryers.

BACKGROUND

Typically atmospheric fryers and vacuum fryers have a number of zones through which product passes to be fried. The fryers including a frying kettle that receives the heated oil, with the kettle having an inlet end and a drained end between which the oil flows, with the oil passing from the outlet end to the inlet end through pumps, filters and heaters.

A conveyor delivers product to the upstream end of the kettle so that the product flows with the oil in a downstream direction. Along the length of the kettle there is usually provided paddles that enter the oil stream and move with the oil stream to aid in moving the product in a downstream direction.

A vacuum fryer is described in International Patent Application PCT/NL2006/000051 (International Patent Publication WO 2007/086724).

Previous continuous fryers have suffered from a number of disadvantages including inconsistently frying the product as a result of high dwell time deviations. This can lead to quality reduction and quality consistency in respect of the product. For example, the natural taste of the product, such as potato, may be degraded, the product may be distorted in shape, while some of the product may have a raised acrylamide content. Other disadvantages are: fatty chips (over fried), increased amounts of small product parts in the fryer that lead to oil quality problems, and longer cleaning times.

OBJECT OF INVENTION

It is the object of the present invention to overcome or substantially ameliorate the above disadvantage.

SUMMARY OF INVENTION

There is disclosed herein a continuous fryer including:

a vessel having a cavity to receive a heated cooking oil;

a pump to circulate the oil so that the oil flows through the cavity in a predetermined direction from an upstream end to a downstream end of the cavity so that product to be fried delivered to the cavity moves in said predetermined direction; and

a flow control device, through which the oil flows to be delivered to said upstream end, to reduce turbulence in the oil in the vessel.

Preferably, the upstream end is provided with a flume.

Preferably, the fryer includes a product moving device including a plurality of spaced plates that engages the oil, with the plates moved in said direction to aid in moving the product in said direction.

Preferably, the plates include a first set of plates, with the plates of the first set being located at spaced intervals along the vessel in said direction, and a second set of plates upstream relative to the oil flow from the first set of plates, and a drive assembly operable to drive the second set of plates at a different speed to the first set of plates.

Preferably, the plates are part of a paddle system including a plurality of shafts from which there extends a plurality of paddles, with the paddles being driven at an angular velocity, and wherein the paddles of the first set can be driven at a different speed to the paddles of the first set.

Preferably, the paddles of the first set have a peripheral velocity substantially the same as the oil in said upstream end.

Preferably, the flow control device is a body with a plurality of passages extending in said direction through which the oil is delivered to said upstream end.

Preferably, the passages are surrounded by the body.

Preferably, said flow control device is also configured to control the flow therethrough so that flow in said direction can vary, transversely across the flow.

Preferably, said device includes at least one plate having a plurality of passages, with the plate movably attached to the body to move the plate passages relative to the body passages to adjust said flow.

Preferably the device further includes at least one temperature sensor downstream of said device, a controller that receives a signal from each sensor, and a motor operatively associated with each plate to move the associated plate so that movement of the plate is at least partly determined by the temperature sensors.

Preferably, said plates includes a plurality of passages through which the oil flows to exit the body passages, with the plate passages moved relative to the body passage to adjust flow through the body passages.

Preferably, said device is configured so that the oil flows in a generally homogeneous and laminar manner at said upstream end.

Preferably, the oil at said upstream end has a width and a depth, with the oil at said upstream end, across the width and depth, flows in said predetermined direction in a generally linear manner.

DESCRIPTION OF EMBODIMENTS

InFIG. 1of the accompanying drawing there is schematically depicted a continuous fryer10. In this embodiment, the fryer10is an atmospheric fryer. However in an alternative embodiment the fryer may be a vacuum fryer as described in the abovementioned International Patent Application.

The fryer10includes a vessel (kettle)11that is longitudinally elongated in the direction12.

The vessel11receives oil13that has an upper surface14. The oil13is moved in the vessel11in the direction12from an upstream end15to a downstream end16.

A conveyor17, having an upper conveyor surface18moves the product19(such as uncooked potato slices) in the direction20so that the product19is delivered to the vessel11adjacent the upstream end15.

The fryer10also includes a plurality of paddle assemblies21, and a further paddle assembly22. Each of the paddle assemblies21includes a shaft23from which there is generally radially extending a plurality of plates (paddles)24.

Each of the shafts23is driven in the angular direction25by a motor and transmission assembly26so that the plates24, when in the oil13, move essentially in the direction12to aid in moving product in the direction12in a generally uniform manner. Preferably the assembly26operates the shafts23so that they have the same angular velocity. The shafts23extend generally transverse of the direction12.

The paddle assembly22includes a shaft51from which there radially extend a plurality of plates (paddles)27. The shaft51is driven in the angular direction28so that the plates27when in the oil13, moves in the direction12, again to aid in moving product in the direction12. The shaft51is driven by a separate motor and transmission assembly29that can provide the shaft51with a different angular velocity relates to the shafts23. Accordingly, the plates27may have a greater velocity, when in the oil13, than the velocity of the plates24. The velocity of the plates24is determined by the product dwell time.

The fryer10also includes a heater (heat exchanger)30that heats the oil and returns the oil to the upstream end15as well as the downstream end16.

A pump39, via line40, receives oil from a downstream portion of the vessel11and delivers the oil to the heater30. From there, lines41and42deliver oil to the vessel11. In particular, the line41delivers oil to a line43extending to the upstream end15, and a line44to extend to the downstream end16.

The line40may include filters, and a means for adding oil to the fryer10.

Above the vessel11is hood32with a stack33that removes vapour produced by the fryer10.

Located adjacent the upstream end15is a flow control device34, the device34may be a collimator. The flow control device34aids in controlling flow of oil in the direction12so that the oil flow, at least in the upstream end, is generally homogeneous throughout its depth and width, and is generally laminar.

Preferably the flow control device34is a plate or body35that is provided with a plurality of passages36that extend longitudinally in the direction12and through which the oil flows in the direction12to be delivered to the upstream end15. The passages may be slots or surrounded by the body35.

Preferably oil is delivered to a generally closed chamber37so that the flow control device34closes the chamber37. The oil is delivered to the chamber37under pressure and flows through the passages36to be delivered to the upstream end35.

Preferably adjacent the upper end15there is a flume provided by the vessel floor38that slopes downwardly in the direction12beneath the shaft51.

In the embodiments ofFIGS. 2 to 6, the flow control device34includes the body35with passages36, however there is slidably mounted on the body35one or more plates45. The plates45are slidably mounted on the body35for linear movement relative thereto in the direction46. The direction46is generally perpendicular to the flow direction12.

Each of the plates45is provided with a plurality of passages47that can be moved from a position aligned with the passages of36, to a position at which they are partly aligned, or not aligned. Accordingly, the plates45can be moved to restrict flow through the passages36.

Preferably each of the plates45is provided with motor (linear actuator)48that are operable to each move their associated plate45in the direction46.

InFIG. 5. the passages47are illustrated as aligned with the passages36. InFIG. 6, the passages47are slightly misaligned with the passage36so as to restrict flow.

Preferably, there is located downstream of device34, a plurality of temperature sensors49, located in the vessel11and submerged in the oil13. Preferably the temperature sensors49are located adjacent or at the upstream end15, but downstream of the device34. The sensor49are connected to a controller50so that the controller50receives signals from the sensors49, the signals being indicative of the temperature of the oil adjacent the particular sensor49. The controller50is operatively associated with each of the motors48, so that the controller50can adjust the positions of the plates45, to thereby adjust the temperature transversely across the vessel11, by controlling the flow rate through each plate45, and therefore the associated passages36. Accordingly the sensors49aid in determining the position of the plates45.

The above described preferred embodiments have a number of advantages including reducing turbulence at the upstream end5which results in a more uniform product, increasing oil speed in the end15, and enables control of the frying process to inhibit the production of acrylamide and over fried products. By operation of the motor and transmission assemblies26and29product dwell time is controlled so as to inhibit the build-up of product, thereby contributing to product consistency. A further advantage of controlling the oil speed is that smaller portions of the product are inhibited from building up. Small particles do not build up at the bottom of the vessel11. This improves oil quality and increases production.

A still further advantage of the above described preferred embodiments is that product does not tend to cluster, again contributing to consistency of product quality, as the fryer10operates in the manner of a single layer fryer at the upstream area of the fryer10following the assembly22.

The delivery rate of product19can be maintained at a generally consistent rate as there is little build-up of product in the vessel11. As the delivery rate of production is substantially consistent, fluctuation in temperatures and dwell times are reduced, increasing product quality. That is dwell time deviation is reduced.