EP0182878A1

EP0182878A1 - Continuous feed oven

Info

Publication number: EP0182878A1
Application number: EP19850902900
Authority: EP
Inventors: Robert B. Forney
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-05-31
Filing date: 1985-05-29
Publication date: 1986-06-04
Also published as: WO1985005545A1; AU4435285A; EP0185059A1; WO1985005546A1

Abstract

Un four commercial à alimentation continue a trois zones de température réglable. Une zone centrale (10) est maintenue à une température élevée pour rissolement des produits. Cette zone comprend des soufflantes de recirculation (60 et 62) qui dirigent de l'air chaud dans des rangées de tubes (42) pour incider sur le produit qui passe entre ceux-ci sur un convoyeur. Des brûleurs (56 et 58) à l'intérieur de la zone centrale chauffent l'air extérieur afin de maintenir la température appropriée. L'air des brûleurs est également distribué latéralement, dans des zones extérieures où de l'air frais est également introduit afin de réduire la température jusque dans une plage de température modérée de cuisson. Des cheminées d'évacuation (140 et 146) à chaque extrémité du four aspirent l'air épuisé du four. Le profil de températures de traitement d'aliments comprend ainsi une zone de réchauffement modéré, une zone de rissolement à chaleur élevée et une zone moderée d'équilibrage.A commercial continuous feed oven has three adjustable temperature zones. A central zone (10) is maintained at a high temperature for browning of the products. This zone includes recirculation blowers (60 and 62) which direct hot air into rows of tubes (42) to incide on the product which passes between them on a conveyor. Burners (56 and 58) inside the central area heat the outside air to maintain the proper temperature. The air from the burners is also distributed laterally, in outside areas where fresh air is also introduced in order to reduce the temperature down to a moderate cooking temperature range. Exhaust chimneys (140 and 146) at each end of the oven suck the exhausted air from the oven. The food processing temperature profile thus includes a moderate warming zone, a high heat browning zone and a moderate balancing zone.

Description

-I-

£ £ I £ I I I £ __ l I __ -i

CONTINUOUS PEED OVEN

BACKGROUND OF THE INVENTION

The field of the present invention is commercial ovens of the type employing a conveyor to convey products continuously therethrough.

Commercial ovens have been developed for the cooking of meat products and the like which empioy a porous belt conveyor extending through a cooking zone where gas burners or electric heaters create an atmosphere for continuous cooking of products on the belt passing therethrough. Such devices generally are designed to attempt to provide cooking uniformity to the product, to minimize weight loss of the product and to effect an even browning on the surface of the product. Additionally, system parameters of such devices preferably minimize heat loss, minimize exhausted pollutants and maximize cooking efficiency. To achieve cooking uniformity, proper browning and minimum weight loss, the cooking temperature, the dwell time within the oven, the feed rate therethrough and the amount of moisture in the air have been controlled. The circulation of air within the oven aids in insuring cooking uniformity. Exhaust filters and the like have been employed for eliminating grease and other pollutants from the exhaust air. Minimizing heat loss through the employment of double wall construction and insulation have also been employed. In spite of the ability to vary the foregoing parameters, optimum cooking flexibility has not been realized in a single oven system. The cooking requirements for any given product may be mutually conflicting. For example, the browning requirement may dictate a higher than optimum tempera¬ ture within the oven while reducing sufficient dwell time to insure uniform cooking throughout. Excessive fluids may be lost in such systems resulting from an inability to control the cooking profile of the product. Additionally, efficiencies may be compromised by excessive heat loss through the inefficient exhausting of heated oven air. The exhausting of such air loaded with the constituents driven off of the product by the cooking process require expensive or labor intensive exhaust scrubbing apparatus to meet environmental standards. Consequentl cooking systems have been sought which provide maximum control of the cooking profile for optimum and uniform results. Minimization of energy loss and exhausted pollutants have also been sought.

SUMMARY OF THE INVENTION

The present invention pertains to a continuous feed oven and the cooking process therefor. Multiple oven zones are employed to provide an optimum and easily controlled cooking profile. The arrangement exhibits efficient heat usage and minimum exhaust pollutants. A central zone includes a heat source and air recirculation for browning of the cooking product. Zones to either side of the central zone receive air heated by the central zone to provide an initial tempering of the product from the cold state at a temperature substantially below that of the browning zone and an equilibration of the browned product, again at a lower temperature state, to insure uniform cooking throughout the product. In this way, efficient control over the cooking profile provides maximum cooking efficiency, proper browning, minimum weight loss and uniform cooking throughout.

The multizone oven of the present invention may be further enhanced through the flow of heated air therethrough. Circulating air within the heated central zone promotes rapid and uniform browning of the product. A burner may be employed within the zone by which recirculation air passes. In this way, constituents driven off by the cooking process may be burned to reduce pollutants within the system. The addition of outside makeup air to the burner creates a controlled source of additional air such that flow from the central zone to the outside zones distributes heat thereto^". Arrays of tubes may be employed for specifically directing heated air to the product from both sides of the conveyor in the browning zone. The tubes may additionally direct excess air into the outside zones. By supplying air directly from the burner or burners, reduced contaminants within the air are distributed either to the product during browning or into the outlying zones.

To further control the cooking profile, heated air exiting from the central zone into the outside zones may be mixed with entrained ambient air for a reduction in tempera¬ ture to create the proper tempering and equilibration environ¬ ments. ^' As a result, all three zones may be independently controlled as to temperature while providing heat only to the central zone. The heated air exhausted from the central zone may then flow at a reduced temperature through the outside zones for continued cooking of the product. Exhaust from the outside zones is, therefore, at a much reduced temperature after the heated air has achieved maximum use in the cooking environment.

The distribution of air within the central zone may also improve the efficiency of the system. Air passing by the burner is substantially cleansed of entrained pollutants. This air may be distributed directly to the outside zones by laterally extending tubes without passing through the cooking environment in the browning zone. Additionally, an appropriate splitting of flow between tubes can inhibit general flow from the browning zone into the outside zones. Consequently, much fewer pollutants are again entrained in the air and the resultin exhaust is substantially reduced in pollutants.

In another aspect of the present invention, the tubes in the central, browning zone are conveniently mounted as part of two manifolds providing outlets from plenums on the upper side and lower size of the conveyor belt. The manifolds may be easily removed and replaced to accommodate variations in product size or the like. A moat may be incorporated with the lower manifold to provide water cooling for receipt of grease drippings, and provide additional humidity into the browning zone for distribution to all zones.

The arrays of tubes create circulation control to specific locations on the conveyor. This makes the process far less dependent on the overall product load. The tubes are arranged with succeeding tubes in the direction of con¬ veyed product being offset. This varries the flow distribution for promoting cooking uniformity. The flow rate through the tubes may be sufficient to create turbulance in the cooking areas. The majority of the tubes are directed at the conveyor within the browning zone. Additionally, the end rows of tubes may be curved and directed laterally at the outside zones to create turbulant flow within these zones as well.

The process of cooking realized by the present configuration includes the optimum steps for achieving a uniform, properly cooked and browned product. The product is allowed to slowly rise in temperature in the tempering zone, being subjected to a moderate cooking temperature range. Once heated, a browning of the outer surface is next achieved at an elevated, browning temperature range with high velocity air impingement. Finally, the heat within the product received during browning as well as during tempering is allowed to migrate to the center of the product for complete cooking in the equilibration zone where additional moderate cooking at a cooking temperature range continues. Naturally, the temperature ranges may be varied, the relative lengths of the zones may be varied in the oven design and the overall cooking time may be varied. Consequently, substantially complete control over the cooking process may be achieved.

Accordingly, it is an object of the present inven¬ tion to provide an improved continuous feed oven and commercial cooking process. Other and further objects and advantages will appear hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a plan view of an oven of the present invention.

Figure 2 is a side elevation of the oven of Figure 1 _

Figure 3 is a cross-sectional elevation taken along line 3-3 of Figure 1.

Figure 4 is a cross-sectional elevation taken along line 4-4 of Figure 1.

Figure 5 is a cross-sectional elevation taken along line 5-5 of Figure 2.

Figure 6 is a cross-sectional elevation taken along line 6-6 of Figure 2.

Figure 7 is a plan view of an upper manifold of the present invention.

Figure 8 is a side view of the manifold of Figure 7.

Figure 9 is a side view of a lower manifold of the present invention with a portion broken away to illustrate a moat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning in detail to the drawings, a continuous feed oven is illustrated having three oven zones. The first or central oven zone is contained within a first housing, generally designated 10. A second or tempering zone is con¬ tained within a second housing, generally designated 12; and a third or equilibrating zone is defined within a third housing, generally designated 14. Means for conveying product through the continuous feed oven are provided by an endless belt 16. The belt 16 is preferably of porous, metallic construction.

The belt is shown to extend around conventional roller mechanisms 18 and through a conventional cleaning bath 20.

The central zone contained within the first housing 10 is designed for a browning function in the cooking process. The central housing 10 is substantially closed to promote recirculation of air within the housing to maintain a high temperature environment. The housing includes sidewalls 22 and 24, end walls 26 and 28 and a top 30 all of double wall construction. In this way, radiant heat loss is minimized. A bottom panel 31 completes the enclosure. The central housing 10 is substantially larger than the outside housings 12 and 14 in order to accommodate the heating and recirculating functions not associated with the tempering and equilibration zones.

In the browning zone, the conveyor 16 extends between an upper plenum 32 and a lower plenum 34. The upper plenum 32 is generally rectangular in plan so as to extend fully across the conveyor 16 as well as along the length of the browning zone. The lower side of the upper plenum 32 is defined by an upper outlet manifold. This manifold includes a plate 36 through which tubes 38 extend. The overall assembly of the plate 36 and the tubes 38 is mounted to the plenum 32 for easy removal and replacement. In this way, cleaning is facilitated. Additionally, variations in tube diameter and length for optimum air flow to the product with clearance for passage of the product therebeneath are realized. As may best be seen in Figures 7 and 8, the upper manifold tubes are arranged in staggered array such that any path followed by the product along the conveyor will be equally subjected to air flow through the tubes 38. "The tubes 38 are of two types. The first type of tubes is straight while two outside rows have bent tubes for directing flow laterally as will be further discussed below.

The lower plenum 34 is similarly constructed to that of the upper plenum 32, it also being rectangular in plan for uniform distribution of heated air to the conveyor 16. The upper side of the lower plenum 34 is defined by a lower outlet manifold having a plate 40 and tubes 42. The tubes 42 extend upwardly to the underside of the conveyor 16 as can best be seen in Figures 3 and 4. The plate 40 includes an upwardly extending flange 44 about the periphery to create a moat for receipt of cooling water. The moat is to be provided with a source of water which will evaporate continuously during steady state operation of the oven. Additionally, water may pass across a weir formed in one side of the flange 44 to carry off suspended grease dripping from the product through the conveyor 16. Because the supplied air to the lower plenum 34 is preferably well above a temperature at which grease will begin to smoke, the water moat insures against pollution of the browning zone by grease burning on the lower manifold. The lower tubes 42 are also preferably arranged as two types with the end rows including curved tubes similar to those employed in the upper manifold.

Through the employment of the upper and lower manifolds, properly heated air is projected through the tubes 38 and 42 at the product being conveyed through the browning zone. Air is released directly at the product and then is allowed to flow away from the product and laterally from the zone as can best be seen by the arrows in Figure 3. The air is then returned to the upper portion of the central housing 10. Space around the plenums 32 and 34 allows open communication of the air from the area of conveyor 16 of the upper portion of the housing 10.

During the time that the product takes to pass through the central housing 10, the outer surface of the product is subjected to a relatively high temperature. This temperature is within an effective browning temperature range, preferably around 800^#F to 1000^*F. A conventional oven is unabl to employ such temperatures as the product cannot withstand such elevated temperatures for a sufficient period of time to cook the product throughout. With the versatility of the present system, browning may be effected with such temperatures while the remainder of the cooking process continues at a lower, cooking temperature range around 400^*F.

To provide heated air to the plenums 32 and 34, sources of heat and air circulation means are provided above the browning zone within the central housing 10. Two enclosed cavities 46 and 48 are illustrated in the present embodiment as being within the central housing 10. The cavities are defined by cylindrical drums extending between the end walls 26 and 28. The cylindrical shape of the enclosed cavities 46 and 48 is selected principally for ease of fabrication rather than for any specific functional advantage. Each of the enclosed cavities 46 and 48 is divided by a baffle 50 which extends partially across the cavity. The baffle 50 is shown to be square in Figure 3 such that air may flow around the baffle on all sides. Each cavity 46 and 48 also includes an inlet port 52. A cover 54 over a portion of the port 52 allows for increased access and a facility for controlling the effective opening of the inlet 52.

Associated with each cavity 46 and 48 is a source of heat. Illustrated in the preferred embodiment are two burners 56 and 58. The burners 56 and 58 exhaust into the enclosed cavities 46 and 48 adjacent the inlets 52. The -burners have external air supplies principally through blowers 60 and 62.

On the other side of the baffle 50 from the blowers 56 and 58 in each of the enclosed cavities 46 and 48 are means for circulating air within the central housing 10. Blowers 64 and 66 are arranged within the cavities 46 and 48 with inlets in communication with the interiors of the cavities. Thus, air heated by the burners 56 and 58 and returning through the inlets 52 passes around the baffles 50 to be drawn into the blowers 64 and 66.

A conduit 68 extends between the lower blower 66 and the upper plenum 32. The conduit 68 is associated with the outlet of the blower 66 such that pressurized heated air enters the upper plenum 32 for distribution through the tubes 38. The upper blower 64 is placed in communication with - the lower plenum 34 by means of a conduit 70 as best illustrated in Figure 3. The conduit 70 extends from the outlet of the upper blower 64 to an inlet 72 on the side of the lower plenum ^'34. In this way, heated air from the upper cavity 46 is directed under pressure to the lower plenum 34 for distribution through the tubes 42 to the underside of the conveyor 16. Baffles 74 and 76 within the upper and lower plenums 32 and 34, respectively, ensure proper distribution of incoming air to all of the tubes 38 and 42. Air then returns to the upper portion of the housing 10 and the inlets

52 as discussed above.

The central housing 10 is conveniently structured so as to be elevated on screw jacks 78. The screw jacks 78 raise the upper portion of the housing including the upper plenum 32, a door 80 and an upper portion 82 of the conduit 70. The raising of the upper portion of the housing 10 may be used to facilitate cleaning or accommodate oversized product. A liquid seal 84 insures proper sealing of the conduit 70 while an extension on the door 80 and one extended sidewall panel 86 maintains the housing 10 in a substantially closed condition.

Adjacent the central housing 10, one of the outside housings 12 defining the tempering oven zone. The housing 12 does not include any heating or forced circulation means. Instead, the tempering zone receives heated air from the curved tubes 38 and 42 most adjacent the housing 12 through a first opening 88. The housing 12 is placed immediately adjacent the side of the central housing 10 such that the conveyor 16 may run continuously from the tempering zone to the browning zone. The curved tubes 38 and 42 are shown to be in alignment with the opening 88 to introduce unrestricted air flow into the tempering zone. The air flow introduced is directly from the plenums after having passed by the burners 56 and 58.

Therefore, the flow is reduced in entrained pollutants.

Because the housing 10 is closed, but for the opening 88 and the corresponding opening on the other side discussed below, the air flow from the housing is volumetrically determined by the makeup air supplied by the blowers 60 and 62 to the burners

56 and 58, the increase in vapor and any increase in volume due to heating of the atmosphere within the housing 10.

The housing 12 is elongate and includes a cover divided into three parts 90, 92 and 94. The central cover 92 is hinged, as can best be seen in Figure 5, to swing open for access to the interior of the oven. Each cover part 90, 92 and 94 is of double wall construction to retain heat and is generally formed in an angular U-shape in cross section. Support on either side is provided by a side skirt 96 in turn supported on the basic frame of the machine. Below the conveyor 16 is a drip pan 98 having an inclined bottom portion for drainage of grease and the like.

At the end of the tempering housing 12 is an exhaust system having an exhaust stack 100 in communication with an upper exhaust manifold 102 and a lower exhaust manifold 104. The upper exhaust manifold 102 employs an elongate orifice 106 in the bottom of the manifold 102. The manifold 104 also includes an elongate orifice 108 which is located on the inner side thereof. In each case, air is drawn through the orifices 106 and 108 into the manifolds 102 and 104 to be conveyed laterally from the belt path to the exhaust stack 100. The exhaust^' stack 100 includes a conventional exhaust fan for forced exhaust of the air. The fan is able to effect air flow in the direction of the exhaust from the central housing

10. For conveyor access into the tempering zone, an opening

110 is arranged at the end of the tempering zone outwardly of the exhaust. An adjustable door 112 optimally minimizes the height of the opening 110 to accommodate both the belt and the product sitting thereon without interference and yet to reduce the amount of air which may flow therethrough and into the exhaust 100.

Cool air manifolds 114 and 116 extend across the tempering zone within the housing 12. These manifolds are provided by pipes which are open to the outside air at either end. Damper elements 118 and 120 are associated with the outside openings of the ends of the manifolds 114 and 116 as can best be seen in Figure 2. Ports 122 and 124 extend uniformly across the downstream side of the cool air manifolds 114 and 116 for distributed and unobstructed communication with the interior of the housing 12. Through control of the damper elements 118 and 120, outside air may be introduced in limited quantity to mix with the high temperature air exhausted through the outside row of tubes 38 from the brown¬ ing zone. The exhaust fan located in the stack 100 insures flow from the cool air manifolds 114 and 116.

At the opposite side of the browning zone is an equilibration zone. The equilibration zone is located in the housing 14 which is constructed substantially identically to that of the tempering zone. This is also true of the exhaust, system at the outer end thereof. Naturally, the • relative length of the zones may vary depending on the needs of the product for which the oven is designed. Exhaust fan speeds may also be varied as well as damper element settings to accommodate variations in the desired cooking profile.

The physical operation of the equilibration zone is substantially identical to that of the tempering zone and similarly includes three housing sections 126, 128 and 130 of double wall construction, a slanted drip pan 132, an opening 133 between the browning zone and the equiliberation .zone and cool air manifolds 134 and 136. The cool air manifolds 134 and 136 include ports 138 and 140 extending across the length of the manifolds and damping elements 142 and 144 on either end of the manifolds 134 and 136. The exhaust system includes an exhaust stack 146 with an exhaust fan for forced flow there¬ through. An upper manifold 148 includes a orifice 150 for introduction of exhaust gases to the stack 146. A lower exhaust manifold 152 similarly includes an elongate orifice 154.

In steady state operation, the oven conveys product by means of the conveyor 16 from right to left as seen in Figures 1, 2 and 4. The product is placed on the conveyor by conventional means (not shown) and received from the conveyor at the other end by conventional means (also not shown). Heated air is generated by the burners 56 and 58 within the enclosed cavities 46 and 48. Outside air is employed for the burners such that some air flow is induced into the oven. Air within the cavities 46 and 48 is then drawn around the baffles 50 to blowers 64 and 66 which in turn direct air into plenums

Q 1 » --■. _-_« 32 and 34. This air is then directed by means of tubes 38 and 42 toward the product in the central zone. The temperature of this air is in a range best suited for browning with air impingement. The browning temperature range is preferably around about 800^*F to 1000^*F. The air velocity impinging upon the product is preferably in the range of around 7,000 to 10,000 fpm.

The size, consistency, type of product, air flow, temperature, conveyor speed and length of zone are highly interrelated in terms of cooking and browning results. There¬ fore, optimum conditions must be empherically determined. Certain considerations independently affecting the range of individual parameters, however, should be understood. In the browning zone, above 1000^*F the effect on the product tends not to increase linearly. At the same time, component costs and efficiencies are detrimentally effected. On most commercially prepared meat products, below about 80O^βF the browning process would be too slow. The product would need to be subjected to the browning process for an extended period of time resulting in excessive overall cooking in this zone. With abnormally large product pieces, the temperature may be as low as 600^*F because excessive cooking in this zone no longer is a problem.

With regard to air flow through the tubes 38 and 42, velocities in excess of 10,000 fpm generally require more extensive equipment and result in inefficiencies due to excessive flow resistance. The additional advantages realized by velocities in excess of that amount do not increase linearly. Therefore, for practical reasons, 10,000 fpm is considered at the upper end of the range of air velocities.

On the other hand, a minimum of 7000 fpm is simply in the area where effective flow can result in reduced oven tempera¬ tures into a range allowing reasonable temperature levels. When the products being cooked are battered or breaded, the air velocities impinging upon the product must be further reduced to avoid loss of coating.

The air directed at the product is then allowed to move laterally from the center portion of the browning zone to side spaces for open communication back to inlet ports 52 associated with the cavities 46 and 48. The inlets 52 are adjacent the burners 56 and 58 such that the entrained pollutants will be incinerated in the enclosed cavities. Because the housing 10 is substantially closed, the majority of the air recirculates within the housing. Humidity is also introduced into the browning zone. The moat associated with the lower manifold contributes moisture. Conventional means such as steam jets may also be provided for contributing moisture to the heated environment.

Because of the outside air contributed by the blowers 60 and 62, steam and vaporized water from the moat, volumetric flow from the browning zone occurs through openings 88 and 133. It is preferred that air having passed by the burner is dis¬ tributed through the openings 88 and 133 because of the incineration of pollutants therein. Consequently, curved tubes are provided for appropriate distribution.

By providing sufficient flow capacity to the curved tubes, -there is little cause for the air released from the straight tubes within the browning zone to exit through the openings 88 and 133. Inhibition to flow from the browning zone is achieved by arranging the upper and lower manifolds such that there is at least the same amount of flow from the curved tubes as there is added volume flow resulting from burner air sources, steam jets, vapor from the moat in the lower manifold and any other source of increased volume of gasses within the first housing 10. Relative tube size and numbers of tube may be used to give this result. Emperical testing is the most appropriate method for fixing this result as a variety of products and oven configurations will vary the requirements.

Air flow through the housing 12 is enhanced by a fan within the exhaust 100. Cool air is also introduced through manifolds 114 and 116 to reduce the temperature from the curved tubes (800^βF to 1000"F) to a cooking range of around about 4C0^βF. The air distributed to the product in the tempering zone is also reduced in velocity from that existing the tubes 38 and 42 to around about 7,000 fpm. The tempering zone receives cold product which may be frozen, refrigerated or even at ambient temperature. Cooking to bring the product temperature up thus commences in this moderate zone. The product is then browned in the high temperature, high velocity zone and passed to the equilibration zone.

Flow through the equilibration zone is substan¬ tially the same to that in the tempering zone but in the opposite direction. Once again the temperature is dropped to a moderate cooking range to continue the introduction of heat into the product. The high surface temperature achieved during ^'browning is also given time to spread into the product. The belt speed, temperature ranges, humidity and rate of air circulation and impingement contribute to the uniform and complete cooking of the product with adequate surface browning. The generation of heat within the central zone with distribution of that heat outwardly creates a highly efficient system with a minimum of exhausted heat. The con¬ tinuous incineration of entrained pollutants within the oven and selected distribution of air cleaned thereby toward the exhausts is believed to eliminate the need for pollution control in most circumstances.

Thus, a versatile continuous feed oven providing an advantageous and easily controlled temperature profile and the process of cooking using such a profile are disclosed. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein- The invention, therefore, is not to be restricted except in the spirit of the appended claims.

Claims

What is claimed is:

1. A continuous feed oven comprising a first oven zone including a first housing, a source of heat in said first housing and circulation means for recirculating air within said first housing; a second oven zone including a second housing adjacent a first side of said first housing; a first opening between said first side and a first end of said second housing; a third oven zone including a third housing adjacent a second side of said first housing; a second opening between said second side and a first end of said third housing; conveyor means for conveying product there¬ through, said conveyor means extending seriatim through said second oven zone, said first oven zone and said third oven zone.

2. The continuous feed oven of claim 1 wherein said conveyor means passes product seriatim through said second oven zone, said first opening, said first oven zone, said second opening and said third oven zone.

3. The continuous feed oven of claim 1 wherein said source of heat includes a burner within said first housing having an external air supply.

4. The continuous feed oven of claim 1 wherein said conveyor means includes a porous, metal, continuous belt.

5. The continuous feed oven of claim 1 wherein said circulation means includes two blowers positioned within said first housing, said first housing being substantially closed and further including an upper plenum positioned above said conveyor means, a lower plenum positioned below said conveyor means, conduits from said blowers to said plenums for communication therebetween, and open communication within said first housing between said conveyor means in said first housing and said blowers.

6. The continuous feed oven of claim 5 wherein said blowers are mounted above said upper plenum and positioned vertically one above the other.

7. The continuous feed oven of claim 1 wherein said source of heat includes at least one burner having an external air supply thereto, said circulation means including at least one blower, said first housing having at least one enclosed cavity, said burner exhausting into said cavity, said blower having an inlet in communication with said cavity, said cavity having an inlet from the surrounding first housing adjacent the exhaust of said burner.

8. The continuous feed oven of claim 7 wherein said cavity further includes a baffle located between said burner and said blower.

9. A continuous feed oven comprising a first oven zone including a first housing, at least one burner within said first housing having an external air supply and circulation means for recirculating air within said first housing; a second oven zone including a second housing adjacent a first side of said first housing; a first opening between said first side and a first end of said second housing; a third zone including a third housing adjacent a second side of said first housing; a second opening between said second side and a first end of said third housing; conveyor means for conveying product there¬ through, said conveyor means passing product seriatim through said second oven zone, said first oven zone and said third oven zone, said first housing being substantially closed but for said first and second openings.

10. The continuous feed oven of claim 9 further comprising exhausts at second ends of said second and third housings, said second ends being most distant from said first housing.

11. A continuous feed oven comprising conveyor means for conveying product therethrough; a.first oven zone including a first housing, circulation means for recirculating air within said first housing and having at least one blower within said first housing, an upper plenum positioned above said conveyor means and a lower plenum positioned beneath said conveyor means, conduits between said circulation means and said upper and lower plenums, outlets from said upper and lower plenums directed toward said conveyor means, and open fluid communica¬ tion within said first housing between said conveyor means in said first housing and said circulation means; a second oven zone including a second housing adjacent a first side of said first housing; a first opening between said first side and a first end of said second housing; a third oven zone including a-third housing adjacent a second side of said first housing; a second opening between said second side and a first end of said third housing, said conveyor means extending seriatim through said second oven zone, said first oven zone and said third oven zone.

12. A continuous feed oven comprising a first oven zone including a first housing, a source of heat in said first housing and circulation means for recirculating air within said first housing;

" " " a second oven zone, said second oven zone including a second housing adjacent a first side of said first housing; a first opening between said first side and a first end of said second housing; conveyor means for conveying product there¬ through; an upper plenum in said first housing above said conveyor means; a lower plenum in said first housing below said conveyor means; an upper outlet manifold for said upper plenum, said upper manifold having an upper plate and upper tubes extending therethrough, a first set of said upper tubes being directed downwardly at said conveyor means and a second set of said upper tubes being directed laterally for discharge in alignment with said first opening; a lower outlet manifold for said lower plenum, said lower manifold having a lower plate and lower tubes extend¬ ing therethrough, a first set of said lower tubes being directed upwardly at said conveyor means and a second set of said lower tubes being directed laterally for discharge in alignment with said first opening.

13. The continuous feed oven of claim 12 wherein said upper plate is removably mounted on said upper plenum and said lower plate is removably mounted on said lower plenum.

14. The continuous feed oven of claim 12 wherein said lower plate includes an upwardly extending flange defining a moat on said lower plate about said lower tubes.

15. The continuous feed oven of claim 12 further comprising a cool air manifold extending laterally across said second housing and having outlets therefrom into said second housing and inlets outside of said second housing.

16. Tbe continuous feed oven of claim 15 further comprising damper elements on said inlets.

17. The continuous feed oven of claim 15 further comprising a forced exhaust system at the second end of said second housing most distant from said first housing.

18. The continuous feed oven of claim 12 further comprising a third oven zone including a third housing adjacent a second side of said first housing; a second opening between said second side and a first end of said third housing, some of said second set of said upper tubes and some of said second set of said lower tubes being directed laterally for discharge in alignment with - said second opening.

19. The continuous feed oven of claim 18 further comprising cool air manifolds extending laterally across said second and third housing and having outlets therefrom into said second and third housings and inlets outside of said second and third housings.

20. The continuous feed oven of claim 19 further comprising forced exhaust systems at the second ends of said second and third housings most distant from said first housing.

21. The continuous feed oven of claim 12 herein said upper and lower tubes divide flow thereamong to provide at least as much flow through said second sets of tubes as there is volume of flow added to said first housing.

22. The continuous feed oven of claim 21 wherein said upper and lower tubes divide flow thereamong to provide at least as much flow through said second sets of tubes as there is volume of flow added to said first housing.

23. A process for cooking in a continuous feed oven comprising the steps of tempering food products from a cold state in an atmosphere within the cooking temperature range; browning the tempered food products in an atmosphere within the browning temperature range; and equilibrating the tempered and browned food products in an atmosphere within the cooking temperature range, said steps of tempering, browning and equilibrating being conducted in seriatim.

24. The process of claim 23 wherein said step of tempering is conducted at a temperature of around about 400*F.

25. The process of claim 23 wherein said browning is conducted at a temperature of around about 800-1000^*F.

26. The process of claim 23 wherein said step of equilibrating is conducted at a temperature of around about 400'F.

27. The process of claim 23 wherein said browning includes air impingement on the food products at from about 7,000 fpm to about 10,000 fpm.

28. The process of claim 27 wherein said browning includes air impingement on the food products at from about 7,000 fpm to about 10,000 fpm.