High efficient convection fryer with continuous filtration

Abstract

An improved efficient deep fat fryer is described. Heat exchange within the fryer tank is facilitated by a “U” shaped burner tube which is cantilever mounted from a side of the tank and a burner system is provided to circulate in a spiral pathway products of combustion through the burner tube. An internal turbulator baffle is provided to both facilitate the spiral circulation through the tube and to facilitate heat transfer from the combustion gases to burner tube walls. Exhaust gases are circulated downwardly from the burner tubes to a plenum beneath the tank which also has heat transfer baffle plates to facilitate heat exchange. Ultimately the products are expelled through a flue. The system further comprises filter bags for continuously filtering the oil which are disposed in a sump at the surface of the oil so that oil continually spills from the tank into the sump where it is filtered preferably by one or more bags of cloth material. Other types of filters could be used such as metal or paper or a synthetic in combination with paper so long as porosity is maintained and a filter powder could be used. The system provides a pump for recirculating the filtered oil to the tank.

In the claims  
     
         1 . A deep fat fryer comprising: 
 a housing having a front, sides and back, an upwardly opening tank for holding cooking oil disposed within said housing and having sides and a bottom, an upwardly opening sump having sides and a bottom, disposed within said adjacent tank, and means for directing oil, overflowing said tank from the opening thereof, into said sump;    a U-shaped burner tube having first and second legs extending across said tank, and attached by an end of a first leg to a side of said tank, burner means mounted in said housing and communicating with the interior of said tube through the end mounted on the side of said tank for directing products of combustion therethrough, means carried by said burner tube for circulating said products of combustion through said tube in a spiral path from the burner, successively through the first and second legs of said tube;    filter means removably mounted in said sump for filtering oil overflowing from said tank thereinto; and    circulating means for continuously withdrawing filtered oil from said sump and re-injecting said oil into said tank.    
     
     
         2 . The fryer of  claim 1  further comprising a jet tube extending across an interior side of said tank opposite said sump adjacent the upper portion of said tube, said jet tube coupled to said circulating means and adapted to inject filtered oil into said tank.  
     
     
         3 . The fryer of  claim 2  further comprising means carried by said tank for, in conjunction with said jet tube, circulating oil within said tank to continually sweep debris from the tank bottom and to the surface of the tank.  
     
     
         4 . The fryer of  claim 1  wherein the bottom of said tank defines a port and the second leg of said tube terminates in a downwardly directed elbow extending through said port and adapted to expel circulated combustion gases therefrom.  
     
     
         5 . The fryer of  claim 4  wherein an exhaust plenum is provided within said housing surrounding the bottom of said tank said plenum being in communication with said tube through the tank port; and flue means mounted on said housing in communication with said plenum for expelling circulated combustion products therefrom.  
     
     
         6 . The fryer of  claim 1  wherein said circulating means within said burner tube includes a pair of baffle plates mounted in each leg thereof, disposed at an acute angle to the longitudinal axis of said tube leg, each plate having a central opening therethrough, said plates being in a heat exchange relationship with the combustion gases passing through said tube.  
     
     
         7 . The fryer of  claim 1  wherein said sump is disposed abutting a side of said tank and said means for directing overflow oil from said tank to said sump includes a gutter extending between an edge of the tank opening and an edge of the sump opening.  
     
     
         8 . The fryer of  claim 7  wherein said sump further comprises at least one mesh basket received therein, said basket opening upwardly and normally aligned with the sump opening and abutting the sides thereof said basket being removable from said sump through its opening.  
     
     
         9 . The fryer of  claim 8  wherein said filter means includes at least one upwardly opening porous, bag adapted to be suspended within said basket.  
     
     
         10 . The fryer of  claim 9  wherein said filter means includes a plate adapted to be removably attached to said bag at the opening thereof and dimensioned to engage at least a pair of sides of said basket to support the bag suspended therein.  
     
     
         11 . The fryer of  claim 10  wherein said basket includes a flange surrounding the opening and extending outwardly therefrom, said flange dimension to engage the sides of said sump so that oil entering the sump will pass through the opening of said basket.  
     
     
         12 . The fryer of  claim 11  wherein said plate defines a central opening therethrough and is dimensioned to engage the flange on said basket opening so that oil entering the sump will pass through the opening in said plate, into said bag, therethrough into said basket, and therethrough into said sump.  
     
     
         13 . The fryer of  claim 12  wherein a pair of baskets and a pair of filters therefor are provided.  
     
     
         14 . The fryer of  claim 12  further comprising means for removing said plate and suspended bag from said basket carried by said plate.  
     
     
         15 . The fryer of  claim 12  further comprising means for removing said basket from said sump, carried by said basket.  
     
     
         16 . The fryer of  claim 10  wherein said bag defines a rectangular upper opening and depending sides, said sides tapering inwardly to a bottom, the opening having opposed shoulders extending inwardly from opposed sides, said shoulders adapted to removably engage opposite ends of said plate.  
     
     
         17 . The fryer of  claim 16  wherein said bag is rectangular in cross-section and the opening therein is defined by said opposed shoulders and portions of edges a pair of opposed sides.  
     
     
         18 . The fryer of  claim 9  wherein said bag is comprised of cloth which is 100% virgin cotton, unbleached, 9.7 oz., sateen weave 96×60 (pic per inch) with air permeability of 15-20 CFM, sateen side inward.  
     
     
         19 . In a deep fat fryer including a housing, a tank, means for heating oil in said tank, sump means for accepting overflow oil from said tank, filter means for filtering the overflow oil and circulating means for returning filtered oil to the tank, all contained in said housing, the improvement comprising: at least one filter removably suspended in said sump and adapted to receive said overflow oil, said filter being sufficiently porous so that said oil passes therethrough with entrained sediment therein being retained in said filter, whereby when said filter fills with sediment it can be removed and replaced, or cleaned.  
     
     
         20 . The fryer of  claim 18  where said bag is cotton, of sateen weave having the sateen side the inside surface of the bag.  
     
     
         21 . The fryer of  claim 20  wherein the bag is 100% virgin cotton, unbleached, 9.7 oz., and the sateen weave is 96×60 (pic per inch) with air permeability of 15-20 CFM.  
     
     
         22 . A disposable filter bag for filtering hot cooking oil from a deep fat fryer to remove sediment therefrom comprising: a rectangular in cross-section, upwardly opening four sided, cloth bag of 100% virgin cotton (unbleached) sateen weave 96×60 (Pic per inch), with air permeability of 15-20 CFM and sateen side disposed on the inside the upper opening being rectangular and defined by a pair of opposed shoulders extending across the end portions of the pair of elongated sides and the exposed edges of said sides.  
     
     
         23 . The bag of  claim 22  wherein the sides taper downwardly and inwardly to form a bottom of said bag.  
     
     
         24 . A method for efficiently cooking food in a deep fat fryer comprising the steps of: 
 providing a deep fat fryer having a tank with sides and a bottom for containing cooking oil, means within said tank for heating the oil, a sump disposed adjacent a side of the tank for receiving overflowing oil therefrom, and means for re-circulating the oil from the tank to the sump and for withdrawing oil from the sump and circulating it through the tank;    providing a porous filter, mounting said filter in said sump; circulating overflow oil from the tank through said filter in said sump and filtering said oil therein to remove entrained sediment therefrom; withdrawing filtered oil from said sump, and returning said oil to said tank, periodically removing said sediment filled bag from said sump and replacing it.    
     
     
         25 . The method of  claim 24  wherein said filter is a porous bag, each bag having a rectangular inlet, opening and means at the opening therein for suspending said bag in said sump.  
     
     
         26 . The method of  claim 24  further comprising continuously injecting filtered oil into said tank along a side thereof opposite said sump; sweeping the bottom of said tank with said injected oil to circulate debris toward said sump.  
     
     
         27 . The method of  claim 26  further comprising providing a jet tube extending along a side of said tank opposite said sump said tube in communication with said oil re-circulating means for injecting said oil into said tank.  
     
     
         28 . The method of  claim 25  wherein said filter consists of at least one porous cloth bag of 100% virgin cotton cloth, sateen weave 96×60 (pic per inch) and air permeability of 15-20 CFM, the sateen side being the inside surface of said bag.