The present invention relates to forced airflow systems for food treatment facilities such as vertical rise dryers, smokers, curing chambers, ovens or warmers, coolers, and/or freezers.
Conventionally, several different food treatment system configurations have been used to smoke, cure, dry, cook, cool, or freeze food products such as meat products so as to increase production capacity while attempting to limit the floor space required for carrying out same. In so doing, vertical rise systems have been used with spiral conveyors to move food vertically through the oven while exposing the food to certain processing conditions as it moves from top to bottom or bottom to top. Other systems employ tunnel or linear floor mounted systems that direct food through on trolleys or the like.
Examples of vertical systems include the Northfield LST (Large Spiral Technology) freezer available from Frigoscandia Equipment (fmcfoodtech.com) is a high capacity non-self stacking spiral freezer that employs spiral conveyors with belts available in different widths. Ryson International Inc. of Newport News, Va., provides spiral conveyors that are purported to feature a small footprint and space savings over other brands with load capacities of up to 200 fpm. Another example is the TURBO-Dryer(copyright) from Wyssmont (wyssmont.com). The TURBO-Dryer(copyright) uses a stack of slowly rotating circular trays. In operation, food is fed onto the top tray and, after one revolution, is wiped onto the next lower tray where the operation is repeated. The trays are enclosed in a vertical enclosure that circulates heated air or gas about the food on the trays. Each level in the enclosure may be held at a uniform temperature or the enclosure may be configured with zoned temperature regions having different temperatures. Yet another example is found in U.S. Pat. No. 5,942,265 that describes conveying pepperoni meat to a conventional spiral dryer that includes a number of tiers (typically about 38-42) according to the initial moisture level, the desired final moisture level, the relative humidity of the air, the total amount of water to be removed, the temperature, and the conveyor speed.
An example of a tunnel-like system, available from ALKAR located in Lodi, Wis., employs a plurality of serially connected in-line rooms or chambers with sidewalls and front and rear doors on opposing sides of the rooms that cooperably open and close to hold the food enclosed within each room for predetermined intervals of time as the food progresses forward on the trolleys through the series of rooms forming the tunnel. The walls may include a series of downwardly extending baffles that are aligned with baffles on the opposite wall.
The food is positioned on a trolley that is automatically moved serially horizontally forward through the tunnel and stopped in each chamber for a period of time so that the food on the trolley is exposed to the environmental conditions in the enclosed chamber. The trolley may include multiple batches, trays, or tiers of stacked food items. In operation, the trolley is suspended from rails and enters the open doors of one chamber and the front and rear doors of the chamber close with the trolley stopped therein, thereby defining a closed chamber. One or more trolleys rests in the closed chamber for a period of time during which the chamber is brought to its desired temperature and food can be exposed to heated air-flow. Subsequently, doors on the opposing side of the chamber open, and the trolley then re-initiates movement to pass through the open doorway and enter the next in the serial line of chambers or rooms. Each chamber or room may generate a different environmental condition. The trolley may be connected to a series of trolleys that move in unison through the various chambers.
When processing food through the various systems, the distribution of air or airflow about the food may influence the manner in which the food is cooked, cooled, or otherwise thermally and/or environmentally processed. Uneven distribution patterns may yield a non-uniformly processed product batch. This can be particularly problematic in large capacity continuous process ovens. Other airflow or air distribution patterns may increase the time it takes to reach the desired environmental condition or temperature and may be inefficient in its use of energy.
For example, in general, in the tunnel system, heated air may be directed to flow down from nozzles positioned on the ceiling, discharged at various vertical heights through baffles along one sidewall, and then collected to travel back up to exit in the opposing sidewall of the chamber or at a centrally located exit-air return, that may also be located about the top portion of the chamber. This airflow pattern forces air down about the food on the static trolley, the air rebounds off the walls and floor (and/or trolleys, trays, and screens) and travels back up through the food on the trolley to exit in the air-return. The airflow may be characterized as substantially laminar, potentially inhibiting uniform heat transfer and/or air distribution about the product on the trolley or trolleys. Unfortunately, fresh air may be unevenly distributed in the chamber; the product in the chamber may be non-uniformly exposed potentially leaving dead-spots and/or irregular degrees of exposure to heat and or moisture. This may yield a thermally inconsistent product at various locations thereof so that portions of the product may be overdone, underdone and/or inconsistently processed.
For continuously or substantially continuously moving product lines that move during the thermal treatment itself (such as those employing moving or conveying floors), uniform air distribution may also be problematic in that the moving floors may create physical or air wall blockage or turbulence that can also inhibit the uniform exposure or create undesirable temperature gradients in the system (such as an oven). For example, in round and/or vertical stacked tier ovens or systems that employ substantially circularly configured moving floors, a centrifugal force may be generated that may undesirably force the heated or desired environmental air to the outermost wall of the oven causing a potential large and inefficient temperature gradient at certain zones or regions in one or more tiers or levels of the oven.
In view of the foregoing, there remains a need to provide alternative airflow distribution systems for food processors.
The present invention provides forced fluid flow distribution systems that can direct exogenously introduced fluid (typically primarily a gas or gas mixture such as air) to flow in a flow path that directs the fluid across food held on a food track having an associated width. As such, the flow includes a lateral directional component and may also include a vertical component.
Certain embodiments are directed to operations for treating food traveling through a food processor. Such embodiments include: (a) moving at least one food item over a predetermined travel path in a food processor having a food travel pathway comprising a moving floor and upwardly extending first and second sidewalls located on opposing sides thereof, the travel pathway having corresponding first and second side portions; (b) introducing exogenous fluid into the food processor from a plurality of inlet ports positioned proximate the first sidewall during the moving step to thereby thermally treat the food; (c) exhausting the fluid from the food processor from a plurality of exhaust ports positioned proximate the second sidewall; and (d) directing the exogenous fluid from the introducing step to travel from the first side portion to the second side portion over the food held on the food travel pathway.
The treatment can comprise a thermal treatment (heating and/or cooling), smoking, chemical, radiation, light, and the like. In certain particular embodiments, the food processor includes a plurality of vertically stacked tiers each having a portion of the food travel path thereon, the vertically stacked tiers being longitudinally spaced apart a desired distance. In such embodiments moving the food item can be provided by (substantially continuously) advancing the food to travel successively over a plurality of the different tiers.
Other embodiments are directed at food processing apparatus with forced fluid distribution systems. The apparatus includes: (a) a housing defining an enclosure and having a food inlet and a food outlet; (b) a plurality of stacked tiers residing in the housing, one or more tiers defining a treatment zone within the food processing apparatus, each of the tiers comprising a moving floor that moves the food along its desired travel path over a primary surface of a respective tier; and (c) a forced fluid distribution system in fluid communication with the stacked tiers. The forced fluid distribution system includes: (a) a first plurality of inlet ports positioned on a first side of the food travel path proximate each tier; (b) a second plurality of exhaust ports positioned on a second side of the food travel path across from the plurality of inlet ports proximate each tier; and (c) an exogenous supply of treated fluid operably associated with the inlet ports. In operation, the treated fluid (which can comprise thermally treated air or gas) flows over the food, in selected tiers, as the food is substantially moving through a treatment zone.
The food can be positioned on a floor that includes one or a plurality of side-by-side lanes. The floor can be configured to substantially continue move the food along its travel path during the desired treatment(s) in the processor.
In particular embodiments, the second plurality of exhaust ports are fewer in number than the first plurality of inlet ports and the exhaust ports are configured so that they have a cumulative cross-sectional area that is greater than that of the cumulative cross-sectional area of the inlet ports. In other embodiments, the forced distribution system further includes a pressure relief valve that is configured to release fluid from the food processor upon the detection of elevated pressure levels. The exhaust ports may be also be configured so that they present a cumulative cross-sectional area that is less than that of the cumulative cross-sectional area of the inlet ports.
In particular embodiments, treated gas or air is introduced into an enclosure that has an outer perimeter wall and an inner perimeter wall. The gas/air is introduced into the enclosure from a common wall (either the outer or the inner) and forced to travel across the width of the enclosure to exit from the opposing common wall (i.e., either the inner or the outer, respectively) so that the air travels across the distance of the enclosure between the opposing walls. Ducts may be used so that the physical intake and exit primary channels are disposed together about a single wall or side to reduce the amount of floor space needed to support the air distribution structure. The gas/air may be untreated or treated (thermally, chemically, and the like).
In other embodiments, the present invention provides a forced distribution configuration that is able to provide a predetermined thermal gradient that is substantially constant across a lane or lanes holding food product and/or that inhibits an undue gradient at the edges of one side the enclosure, that may be particularly suitable for vertically stacked tiers having multiple zones or tiers that are held within the enclosure.
In certain embodiments, the enclosure encases a plurality of stacked tiers that each defines at least a portion of a product flow path. At each tier, the product travel path can include a moving floor that is defined by one or more conveyors. The fluid flow system can include a plurality of spaced apart inlet ports that are positioned on a first side of the product travel path and a plurality of spaced apart outlet ports that are positioned on a second opposing side of the product travel path. The distributed fluid can be directed to move over the product on the floor of the travel path, even as the food is advanced during the treatment processing potentially introducing complex air-patterns generated by the moving floors.
In certain embodiments, the fluid distribution system distributes air and may be configured so that the number of inlet ports is greater than or equal to the number of outlet ports. The cumulative cross-sectional area of the inlet ports may be configured in size and/or shape so as to be substantially equal to and/or less than the cumulative cross-sectional area of the outlet ports thereby providing an equilibrated or decreased internal pressure that may promote a vacuum. In other embodiments, the cumulative cross-sectional area of the inlet ports can be greater than that of the outlet ports and the outlet ports can be operably associated with an over pressure relief valve that periodically discharges pressure when a certain level is detected or that substantially continuously discharges air to maintain pressure at a desired level.
In certain embodiments, cooperating side-by-side conveyors on each tier can be configured (such as pairs or more of continuously circulating conveyor belts) so that the food travels first on a first conveyor belt and then moves to an adjacent belt as the food travels greater than one revolution (and typically at least about 1.25-2 revolutions) about a majority of the tiers or levels. In other embodiments, the same conveyor can be used to provide the more than one revolution in each tier (diverting the food into different tracks within the same conveyor) or looping the conveyor to define a greater than one revolution travel path. In certain embodiments, the food item can be physically diverted, dropped, or elevated to a next adjacent underlying or overlying tier for further processing. The food item can be a meat product, and in particular embodiments, may be an elongated meat product (such as a substantially continuous length of linked, crimped, twisted or strand of food product). In other embodiments, the product can be a discrete length of meat product.
Certain embodiments of the invention include methods and systems for directing food through a multi-tier food processor that may be configured as an oven, an incubator, a chiller, a cooler, a dryer or combinations thereof. At least one food item is conveyed over a predetermined travel path in a food processor having a plurality of overlying or underlying tiers which are longitudinally spaced such that the at least one food item travels greater than one revolution in a first tier before it moves to the next tier (which may be aligned or misaligned with the adjacent tier(s) as desired). As the food travels in the travel path thermally treated gas (or gas mixtures that may include air) is forced over the food to treat the food in a predetermined manner. The gas may be heated, cooled, smoked, and/or moisturized or otherwise treated.
In certain embodiments, ducts, tubing, or pipes can be used to position the desired inlet and/or outlet ports at various vertical spaced locations in the enclosure or processing system.
Still other embodiments are directed to nested food processing apparatus. As such, the apparatus includes: (a) an outer processor having spaced apart inner and outer walls defining an enclosure therebetween and a food inlet and food outlet; and (b) an inner processor defining an enclosure having associated upwardly extending sidewalls and a food inlet and a food outlet, wherein the outer processor is configured to receive and surround the inner processor. Each of the inner and outer processors are configured to provide separately regulated operating environments. The outer and inner processors may include: (a) a plurality of vertically stacked tiers held within the enclosure; (b) at least one conveyor operably associated with each tier, the at least one conveyor being configured to move a food item about the tier such that the food item travels greater than one revolution in each tier; (c) transfer means operably associated with the tiers for directing the food to travel to the next selected tier; and (d) a gas flow distribution system. The gas distribution system may include: (a) an exogenous supply of gas (which may be thermally treated and/or comprise particulate matter in particular embodiments); (b) a first plurality of spaced apart inlet ports positioned in the processing apparatus proximate to each tier about a selected one of the inner or outer walls in fluid communication with the exogenous supply of gas; (c) a second plurality of spaced apart exhaust ports positioned in the processing apparatus proximate to each tier about a different one of the walls selected to locate the inlet ports, wherein the second plurality is less than the first plurality to thereby provide fewer exhaust ports. The gas distribution system may be configured to continuously distribute gas while food is moving through each tier.
Each of the inner and outer processors can comprise portions that are ovens and/or can be configured to provide separate temperature regulated (and/or moisture or humidity, air velocity, cooling, heating, sprinkling, gas, and the like) spaces. The outer and inner ovens can include a plurality of stacked tiers held within the respective enclosures and one conveyor and/or a plurality of cooperating conveyors operably associated with each tier. The conveyor and/or cooperating conveyors can be configured to move the at least one food item serially over a major portion of the travel path to thereby provide more than one revolution in each tier. The processors can also include transfer means for directing the food to travel to the next selected (typically the adjacent) tier. The gas flow system may be configured to distribute thermally treated air such that air is forced to travel over the primary surfaces of the conveyors so as to reduce the thermal gradient thereacross, provide a suitable air mass mixture, and/or reduce undesired thermal clustering in the apparatus (hot or cold spots) to provide a processor with increased thermal efficiency.
Still other embodiments are directed to food processing systems having at least one food processing chamber with a plurality of stacked tiers for treating food. The systems include: (a) means for moving food through a food processing chamber having a plurality of stacked tiers, as the food is held on a food support surface; (b) means for directing exogenous gas to flow across food held on the food support surface held inside the food processing chamber while the food is moved in the chamber; and (c) means for exhausting gas comprising the exogenous air from the chamber while the food is moved in the chamber.
The foregoing and other objects and aspects of the present invention are explained in detail in the specification set forth below.