Liquid purification or separation – Processes – Separating
Reexamination Certificate
2000-02-22
2001-05-22
Popovics, Robert J. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S805000, C210S167050, C210S196000, C210S411000, C210S416100, C210S424000, C210S428000, C210SDIG008, C099S330000, C099S403000, C099S408000
Reexamination Certificate
active
06235210
ABSTRACT:
BACKGROUND
The present invention pertains to a recirculating deep-fat fryer used for cooking various types of food products within a heated bath of cooking oil; and more particularly, to a recirculating deep-fat fryer having a combination continuous and batch filtration system.
A typical recirculating deep-fat fryer will include a fryer vat containing a heating bath of cooking oil. The cooking oil is adapted to receive baskets of food products such that the food products will be immersed within and cooked by the heated cooking oil. Such recirculating fryers will also include a heat exchanger and a pump. The pump is responsible for continuously pumping the cooking oil from the fryer vat, through the heat exchanger and back into the fryer vat such that the cooking oil remains at a substantially constant temperature, thereby allowing the food products to be evenly and consistently cooked within the fryer vat.
To extend the useful life of the cooking oil, it is a common practice to filter the particulate food matter from the cooking oil to minimize the carbonization of such food matter within the cooking oil. Some conventional fryers utilize a batch filtration system, in which the cooking oil is drained from the fryer vat and then manually or mechanically filtered before returning the cleansed cooking oil back to the fryer vat. Other conventional recirculating fryers utilize a continuous filtration system, in which a continuous filter is placed within the fluid path of the cooking oil, so as to continuously filter the cooking oil as being recirculated between the fryer vat and the pump.
Even with such continuous filtration recirculating fryers, there is often a need to perform the batch filtration process on the cooking oil at the end of a predetermined period of time, if a more thorough filtration of the cooking oil is desired. Alternatively, the cooking oil in such continuous filtering recirculating flyers must periodically drained from the fryer vat so that the fryer vat may be cleaned out. Once cleaned, it is often desirable to return this drained cooking oil back to the fryer vat.
Accordingly, with either of such conventional systems, it is often necessary to provide extra floor space for a separate batch filtration system that is typically wheeled from fryer to fryer, performing the batch filtration operation. A disadvantage with such batch filtration systems is that during use, they will need to be positioned to the side or the front of the fryer vat, taking up aisle space and work space within the kitchen.
SUMMARY OF THE INVENTION
The present invention provides a combination continuous and batch filtration system for a recirculating fryer where the continuous filter and batch filter assemblies are integrated into a single unit, utilizing a common pump. This unit is substantially compact and is therefore able to fit within the frame of most recirculating fryers. The outlets of the continuous filter and the batch filter are connected to a two-way valve, which is, in turn, connected to the inlet of the common pump. The valve allows an operator to selectively pump cooking fluid from either the continuous filter or the batch filter back into the fryer vat.
The continuous filter assembly includes of a box-like enclosure with an inlet and an outlet and a filter disposed between the inlet and outlet. During normal operation, the continuous filter assembly is preferably seated within the batch filter assembly and is sized to hold only a portion of the entire fryer vat cooking fluid volume at any given time. The present invention therefore provides a continuous filtration system that increases the efficiency of a recirculating fryer as less cooking fluid is required during normal operation and heat loss is minimized.
The batch filter assembly includes another box-like enclosure or “holding tank”, open at the top to allow the continuous filter assembly to fit inside of it. The continuous filter assembly is supported inside the batch filter holding tank by brackets, or other supports, fixed to the inside walls thereof. A filter element for the batch filter assembly is situated in the flow path of cooking fluid through the batch filter. The batch filter holding tank is substantially larger than the continuous filter assembly and is capable of holding the entire cooking fluid volume of the fryer vat.
During normal operation of the recirculating fryer, the continuous filter assembly is seated within the batch filter assembly holding tank and the valve is engaged to allow pumping of cooking fluid from the fryer vat, through the continuous filter, through the valve, through the common pump and back into the fryer vat. At the end of a period of use for the recirculating fryer in continuous filter mode, such as the end of a day, the operator may desire to run a batch filter operation where the entire contents of the fryer vat are filtered while the fryer is not being used to cook food. The operator may then turn off the pump and engage the valve to discontinue flow through the continuous filter assembly. The continuous filter assembly is then removed from its position within the batch filter assembly holding tank and the entire contents of the fryer vat are allowed to be emptied into the holding tank. The operator engages the valve to allow pumping of fluid from the outlet of the batch filter and turns on the pump, thereby pumping fluid from the batch filter holding tank, through the batch filter element, and back into the fryer vat.
Preferably, removal of the continuous filter assembly is facilitated by having the outlet of the continuous filter assembly connected to the inlet of the flow selection valve via a quick-disconnect fitting. It is also preferred that the batch filter assembly have wheels fixed to the base of the holding tank allowing the entire unit to be moved away from within the frame of the recirculating fryer.
The filter element of the continuous filter assembly is preferably comprised of a perforated filter media encapsulated by a nylon bag. This allows larger food particles from the used cooking fluid to be captured on the outside of the bag. Periodically during operation of the filter assembly in continuous filter mode, the pump is activated, either manually or automatically, to reverse flow thereby dislodging food particles from the nylon bag and extending the operating time of the filter assembly. The filter element of the batch filter assembly is preferably comprised of a removable screen that is placed at the bottom of the batch filter holding tank just above the outlet.
In another aspect of the present invention, a recirculating fryer assembly includes a fryer vat for holding cooking fluid and receiving food for cooking, an inlet and an outlet port, a heating element within the fryer vat or within a recirculating path of the cooking fluid, a frame for supporting the flyer vat, and a filtration system having a continuous filter assembly and a batch filter assembly integrated into a single unit and sharing a common pump for pumping fluid from the fryer vat through either the continuous filter assembly or the batch filter assembly and back into the fryer vat.
In yet another aspect of the present invention, a method for filtering the cooking fluid of a recirculating fryer, which has a fryer vat and a pump for recirculating cooking fluid, includes the steps of: (a) providing a continuous filter, a batch filter, and a valve with a first inlet connected to the outlet of the continuous filter, and a second inlet connected to the outlet of the batch filter, and an outlet connected to the inlet of the fryer assembly pump; (b) coupling the inlet of the continuous filter to the outlet of the fryer vat; (c) switching the valve to allow cooking fluid to flow from the continuous filter assembly through the valve and pump; (d) activating the pump so that cooking fluid is pumped from the fryer vat, through the continuous filter, through the valve, through the pump and back into the fryer vat; (e) at the end of a period of running the fryer in continuous filter mode, shutting off the
Hobart Corporation
Popovics Robert J.
Thompson Hine & Flory LLP
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