Patent Description:
In present-day large-scale processing of items such as, for example, chilling, freezing, pasteurizing, cooking, or chemically treating food products, conveying systems are employed in order to provide a continuous flow of the products through the process. In order to provide a relatively long path length within an insulated enclosure of minimal volume and external surface area, a conveyor which transports the items through the enclosure is typically adapted to follow a helical path - termed 'spiral' path in the industry. During transport inside the enclosure, the items are exposed to air heated or chilled to a predetermined temperature or cryogenic gas contained in the enclosure.

Unfortunately, due to the relatively low heat transfer rate between the air or cryogenic gas and the items, the processing still requires exposure of the items to the air or cryogenic gas for a substantial length of time, thus requiring a substantial path length inside the enclosure - i.e. a substantial size of the enclosure - or a very slow movement of the conveyor.

The heat transfer rate between a liquid, such as, for example, water or brine, and the items is substantially larger than the heat transfer rate between the air or cryogenic gas and the items. Therefore, employment of water or brine for the processing requires exposure of the items thereto for a substantially shorter length of time, thus reducing energy consumption and enabling use of a substantially shorter path length inside the enclosure resulting in a smaller system or a higher speed of the conveyor enabling increased throughput.

Furthermore, transportation of a liquid through the system is substantially more efficient and, therefore, cost effective, than the transportation of air.

However, employment of conventional conveyors for submerging the items in a liquid is limited since many items have a density that is less than the density of the liquid. The resulting buoyancy then causes the items to dislodge from their place on the conveyor, clog the conveyor, or float on the liquid surface, likely damaging the item or its packaging resulting in inefficient handling and processing. These effects may also be experienced when the density of the item is not sufficiently larger than the density of the liquid to create enough friction for the item to stay in place on the conveyor against the force of the flow of the liquid.

It is desirable to provide a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same.

It is also desirable to provide a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same that is designed such that the items while submerged in the liquid are secured.

It is also desirable to provide a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same that provides a relatively long path length of the conveyor while minimizing the size of the enclosure containing the liquid.

<CIT> discloses a continuous conveyor mechanism that carries bottles successively down to the bottom of an alkali bath and then carries them up out of the bath to a discharge point. The conveyor mechanism comprises bottle carriers having two rollers for supporting and rotating a bottle as the rollers travel over flanges on a spiral path. As the bottles descend into the alkali, they pass over an upwardly inclined portion to allow the air to pass out of the bottles and the bottles are not buoyant when immersed in the liquid and stay on the rollers when travelling though the liquid.

<CIT> discloses a multi-tiered, spiral path conveyor belt capable of tight radial turning in a restricted area to immerse materials or products into a tank containing a cooling fluid and circulating the cooling fluid past the material or product. The conveyor comprises a conveyor belt having a plurality of belt flites; at least one support capable of supporting the conveyor at a plurality of points along the spiral path; one or more drive chains capable of driving the belt flites of the conveyor belt along the spiral path; and at least one drive unit capable of driving the one or more drive chains. <CIT> discloses a spiral conveyor system according to the preamble of claim <NUM>.

The materials or products may or may not undergo chemical preparation prior to immersion, depending on the type of materials or products to be chilled or frozen. The cooling fluid, which can be food-grade solute, is circulated past the material at a substantially constant predetermined velocity and temperature to freeze the material or product. The cooling fluid is preferably between -<NUM> degrees centigrade and -<NUM> degrees centigrade, and the velocity of the cooling fluid past the material is about <NUM> liters per minute per foot of cooling fluid through an area not greater than about <NUM> inches wide and <NUM> inches deep. Alternatively, the speed of the multi-tiered, spiral path conveyor belt can be adjusted to increase or decrease the rate of immersion of the materials or products into the cooling fluid. All components of the multi-tiered, spiral path conveyor belt can be constructed of food-grade plastics.

Accordingly, one object of the present invention is to provide a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same. Another object of the present invention is to provide a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same that is designed such that the items while submerged in the liquid are secured.

Another object of the present invention is to provide a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same that provides a relatively long path length of the conveyor while minimizing the size of the enclosure containing the liquid.

According to one aspect of the present invention, there is provided a spiral conveyor system according to claim <NUM>.

The advantage of the present invention is that it provides a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same.

A further advantage of the present invention is that it provides a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same that is designed such that the items while submerged in the liquid are secured.

A further advantage of the present invention is to provide a spiral conveyor system for transporting items immersed in a liquid for heating, cooling, or chemically treating the same that provides a relatively long path length of the conveyor while minimizing the size of the enclosure containing the liquid.

A preferred embodiment of the present invention is described below with reference to the accompanying <FIG>, <FIG> and <FIG>.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described.

Referring to <FIG>, a spiral conveyor system for immersing items in a liquid <NUM> is provided. The spiral conveyor system <NUM> comprises tank <NUM> containing the liquid <NUM> such as, for example, water or brine, therein. The liquid <NUM> has a predetermined temperature for processing the items - such as, for example, for chilling, freezing, pasteurizing, or cooking the items - while being immersed therein. For example, the liquid <NUM> is heated or cooled outside the tank <NUM> and then circulated through the tank <NUM> using a pump mechanism (not shown). Optionally, liquids <NUM> other than water or brine are employed, for example, for chemically treating the items when immersed therein.

Conveyor <NUM> receives the items at entry section <NUM> - for example, the items are dropped thereon using another conveyor disposed thereabove - and transports the same downward via spiral <NUM>, as indicated by the block arrows. At the bottom of the spiral <NUM> the conveyor <NUM> crosses over - via cross-over section <NUM> - to spiral <NUM> for transporting the items upward to exit section <NUM> where the items are, for example, dropped onto another conveyor placed below. The conveyor <NUM> forming a closed loop is then returned, for example, by guiding the same below the tank <NUM> - section <NUM> - and via adjustment section <NUM> to entry section <NUM>. Preferably, the conveyor <NUM> is cleaned - for example, when brine is disposed in the tank <NUM> - using conveyor washing mechanism <NUM> placed, for example, after the exit section <NUM>. The, conveyor washing mechanism <NUM> comprises, for example, a set of spray nozzles for spraying water or cleaning solution as the conveyor <NUM> passes by. The conveyor <NUM> may be a conventional self-stacking conveyor 106A, as illustrated in <FIG>, where side walls of the conveyor are adapted for being stacked upon each other while being guided to form the spiral - for example, spiral <NUM> illustrated in <FIG> - using spiral guiding elements 108A. Alternatively, conventional conveyor 106B is moved in a spiral using a conventional spiral support structure 108B, as illustrated in <FIG>, with the spiral support structure 108B providing guidance as well as support.

Alternatively, the conveyor <NUM> is guided at the exit section <NUM> back into the tank <NUM> and returned to the entry section <NUM> through the liquid <NUM> - section <NUM> - inside the tank <NUM>. For example, the conveyor section <NUM> is placed in proximity to the bottom of the tank <NUM>, as illustrated in <FIG>, but is not limited thereto and may be placed at other locations in the tank <NUM> depending on design preferences. The conveyor washing mechanism <NUM> and the conveyor adjustment section <NUM> (not shown) may be placed, for example, near the entry section <NUM> or the exit section <NUM> above the fill level of the liquid <NUM> in the tank <NUM>.

Further alternatively, two connected tanks are provided with each tank surrounding a respective spiral <NUM>, <NUM> and the connection enclosing the cross-over section <NUM>.

The conveyor <NUM> is of conventional design with a plurality of connected sections made of a metal such as, for example, stainless steel, or plastic material such as, for example, Nylon. Alternatively, the conveyor <NUM> is of a belt-type structure made of a sufficiently flexible material. The conveyor <NUM> is driven using, for example, a conventional center drum with friction drive or direct drive.

Referring to <FIG> and <FIG>, a spiral conveyor system for immersing items in a liquid <NUM> is provided. In the spiral conveyor system <NUM> the conveyor <NUM> is guided downward from the entry section <NUM> to the bottom of tank <NUM> via sloped section <NUM>, 202A. The items are then transported upward from the bottom to the exit section <NUM> via spiral <NUM>. Alternatively, the spiral conveyor system <NUM> may be designed to operate in reverse with the spiral being used for transporting the items downward and the slope for transporting the items upward.

Referring to <FIG> and <FIG>, a spiral conveyor system for immersing items in a liquid <NUM> is provided. In the spiral conveyor system <NUM> the conveyor <NUM> is guided substantially vertically downward from the entry section <NUM> to the bottom of tank <NUM> via drop down section <NUM>. The items are then transported upward from the bottom to the exit section <NUM> via spiral <NUM>. While being transported through the drop down section <NUM> the items are secured to the conveyor <NUM> via securing conveyor <NUM> which is placed such that the securing conveyor is oriented parallel to the conveyor <NUM> at a distance adapted to the size of the items for securing the same therebetween. The securing conveyor <NUM> is designed such that the portion facing the conveyor <NUM> is moving in a same direction and at a same speed as the conveyor <NUM>, as indicated by the block arrows in <FIG>. It is noted that the securing conveyor <NUM> may also be employed in the spiral conveyor system <NUM> for securing the items during conveying along the sloped section <NUM>.

While conventional conveyors work well for transporting items immersed in a liquid when the density of the items is substantially larger than the density of the liquid, the employment of the conventional conveyors for submerging the items in a liquid is limited when the density of the items is less than the density of the liquid or not sufficiently larger than the density of the liquid as is the case with many food products causing the problems described hereinabove. In order to enable use of the spiral conveyor systems <NUM>, <NUM>, <NUM> for transporting items immersed in a liquid when the density of the items is less than the density of the liquid, the spiral conveyor systems <NUM>, <NUM>, <NUM> are provided with securing mechanisms for securing the items to the conveyor.

Referring to <FIG>, a securing mechanism not according to the invention comprises a securing conveyor <NUM> which covers the items before entering the spiral <NUM> until after leaving the spiral <NUM>, thus securing the items while being immersed in the liquid, as illustrated in <FIG>. The securing conveyor <NUM> comprises, for example, a flexible mesh-like structure made of metal wire having sufficiently small mesh size and sufficient weight to secure the items <NUM> between the same and the conveyor <NUM>, as illustrated in <FIG>. Alternatively, the securing conveyor <NUM> comprises side walls 330A such that the securing conveyor <NUM> together with the conveyor 106B forms an enclosure containing the items <NUM> therein, as illustrated in <FIG>. While immersed in the liquid the items <NUM> experience buoyancy bringing them in contact with the securing conveyor <NUM> and are conveyed through interaction therewith, as indicated by the block arrow in <FIG>. It is noted that the diagram of <FIG> is upside down for better illustration.

Referring to <FIG>, the securing mechanism according to one embodiment of the invention comprises a non-self-stacking conveyor 106B with the downward oriented sidewalls forming an enclosure containing the items <NUM> therein when stacked upon each other in the spirals <NUM>, <NUM>. The support structure 108B, 110B comprises an inside support framework 108B. <NUM>, 110B. <NUM> that carries the conveyor 106B at the inside edge and an outside support framework 108B. <NUM>, <NUM>10B. <NUM> that carries the conveyor 106B at the outside edge. There is no support structure between the inside support framework 108B. <NUM>, 110B. <NUM> and the outside support framework 108B. <NUM>, <NUM>10B. Because of this fixed support structure on the inside edge, a rotating center drum cannot be used to drive the conveyor 106B. Here the drive mechanism comprises, for example, a sprocket-type drive mechanism comprising sprocket wheels 107B interacting with respective sprockets 107A disposed on one or both outside edges of the conveyor 106B, as illustrated in <FIG>.

While immersed in the liquid the items <NUM> placed on the top side of the conveyor 106B experience buoyancy such that they are in contact with the bottom side of the conveyor section stacked thereon, as illustrated in <FIG> and are conveyed through interaction therewith, as indicated by the block arrow in <FIG>. It is noted that the diagram of <FIG> is upside down for better illustration. The items <NUM> may still get displaced within the enclosure due to the buoyancy and/or current of the liquid. To prevent displacement of the items <NUM> the conveyor 106B and the support structure 108B, 110B may be designed such that the enclosure has a height to provide a snug fit for the item <NUM>. Optionally, the top and the bottom side of the conveyor 106B may have pads made of a material with a friction grip disposed thereon. Unfortunately, application is limited to items of a predetermined size.

Referring to <FIG>, the securing mechanism according to another embodiment of the invention comprises a self-stacking conveyor 106A with the downward oriented sidewalls forming an enclosure containing the items <NUM> therein when stacked upon each other in the spirals <NUM>, <NUM>. While immersed in the liquid the items <NUM> placed on the top side of the conveyor 106A experience buoyancy such that they are in contact with the bottom side of the conveyor section stacked thereon, as illustrated in <FIG> and are conveyed through interaction therewith, as indicated by the block arrow in <FIG>. It is noted that the diagram of <FIG> is upside down for better illustration. The items <NUM> may still get displaced within the enclosure due to the buoyancy and/or current of the liquid. To prevent displacement of the items <NUM> the sidewalls may be designed such that the enclosure has a height to provide a snug fit for the item <NUM>, as illustrated in <FIG>. Optionally, the top and the bottom side of the conveyor <NUM> may have pads made of a material with a friction grip disposed thereon. Unfortunately, application is limited to items of a predetermined size. It is noted that a self-stacking conveyor 106A with upward oriented sidewalls may also be employed.

To prevent displacement of the items <NUM> within the enclosure for items having different size, stalactite-like protrusions <NUM> are attached to the bottom side of the conveyor 106A, as illustrated in <FIG>. The protrusions <NUM> are made of a flexible material - such as for example, rubber - and are sufficiently soft to bend to the contour of the item <NUM> without damaging the same while being sufficiently firm to hold the item <NUM> in place. The number of protrusions <NUM> is determined to be sufficient for securing the items <NUM> while not interfering with the circulation of the liquid <NUM>. As successive sections of the conveyor come together at the beginning of the spiral, the protrusions coming down onto the items <NUM> bend and form a spring-like tension producing downward pressure on the product for holding it down on the conveyor 106A. Preferably, adjacent protrusions <NUM> are oriented perpendicular to each other, as illustrated in <FIG>, to form a barrier surrounding the item <NUM>, as illustrated in <FIG>. It is noted that the diagram of <FIG> is upside down for better illustration. Alternatively, as illustrated in <FIG>, soft foam protrusions <NUM> are employed instead of the rubber protrusions <NUM>. It is noted that the protrusions <NUM>, <NUM> may also be attached to the bottom side of the securing conveyor <NUM> or the bottom side of non-self-stacking conveyor 106B.

In other spiral conveyor systems not according to the invention, the displacement of the items <NUM> is prevented by attaching barriers <NUM>, oriented substantially perpendicular to the direction of movement of the conveyor, to the bottom side of a hanging conveyor 106B with the conveyor 106B being supported by the support structure 108B, 110B via support elements <NUM>, as illustrated in <FIG>. The barriers <NUM> catch the items <NUM> when floating on the liquid <NUM> at the entry section and convey them between two successive barriers <NUM>, as illustrated in <FIG>. It is noted that the diagram of <FIG> is upside down for better illustration.

Alternatively, barriers <NUM> may be attached to the top side of the conveyor <NUM> as illustrated in <FIG>. Preferably, the barriers <NUM> have sufficient height for securing the floating item <NUM> between two successive barriers <NUM>. Optionally, the protrusions <NUM> or <NUM> may be employed to further prevent displacement of the items <NUM> between two successive barriers <NUM>, <NUM>. It is noted that conveyor sidewalls have been omitted in <FIG>, <FIG>, and <FIG> for clarity.

Optionally, trays <NUM> having the items <NUM> disposed therein are employed in the above spiral conveyor systems illustrated in <FIG>, as illustrated in <FIG>, and the spiral conveyor systems illustrated in <FIG>, as illustrated in <FIG>. It is noted that the diagram of <FIG> is upside down for better illustration. The trays <NUM> are made of, for example, a plastic material and have apertures <NUM> disposed in the walls thereof to enable circulation of the liquid <NUM> therethrough. Preferably, the trays <NUM> are sized such that one tray substantially fits the distance between two successive barriers <NUM>, <NUM>. It is noted that conveyor sidewalls have been omitted in <FIG> and <FIG> for clarity.

While the securing mechanisms are only illustrated in combination with the spiral conveyor system <NUM> it will become evident to those skilled in the art that they are not limited thereto but may also be employed with other spiral conveyor systems such as, for example, spiral conveyor systems <NUM> and <NUM>.

<FIG> illustrate entry and exit, respectively, of floating items <NUM> when a hanging conveyor <NUM> is employed. The items <NUM> provided via conveyor <NUM> are placed onto the surface of the liquid <NUM> at entry section <NUM> of the tank <NUM>. The floating items are caught by the barriers <NUM> and/or the protrusions <NUM>, <NUM> and conveyed to the spiral <NUM>. At the exit, the items <NUM> are released from the conveyor <NUM> and float on the surface of the liquid <NUM> at exit section <NUM> where they are caught by barriers <NUM> of exit conveyor <NUM>.

In order to prevent displacement of the items <NUM> while being conveyed along the cross-over section <NUM> in embodiments where the top of the enclosure is provided by a conveyor section stacked thereupon in the spiral, the cross-over section is provided with a cover or a securing conveyor. Alternatively, air is injected into the liquid <NUM> below the cross-over section in order to reduce the buoyancy of the items <NUM>. Air may also be injected along other section of the conveyor path through the liquid in order to reduce the buoyancy of the items <NUM>.

Further alternatively, the spirals <NUM> and <NUM> are placed in close proximity to each other, as illustrated in <FIG>. At the location of the closest proximity the conveyor crosses at cross-over <NUM> from the spiral <NUM> to the spiral <NUM> with the conveyor rotating in the spiral <NUM> in opposite direction to the spiral <NUM>, as indicated by the arrows, thus obviating employment of the above means for preventing the displacement of the items <NUM> during the cross-over.

In order to provide an increased path length of the conveyor <NUM> inside the tank while minimizing the size of the tank containing the liquid, two spirals <NUM> and <NUM> may be provided in a nested fashion, as illustrated in <FIG>. For example, the conveyor <NUM> is moved downward via the inner spiral <NUM>, crossed over via cross-over section <NUM> to the outer spiral <NUM> and moved upward therewith, as indicated by the block arrows. To minimize the cross-over section the outside diameter of the inner spiral <NUM> may be approximately equal to the inside diameter of the outer spiral <NUM>. Alternatively, the spirals may be placed in a non-concentric fashion with the cross-over placed the location of closest proximity of the spirals <NUM>, <NUM>.

Alternatively each of the spirals <NUM>, <NUM> may be implemented using a twin drum set having the conveyor <NUM> spiral around both drums at the same time. Further alternatively, the spiral support structure is adapted for moving the conveyor <NUM> down and up a same spiral with adjacent stacked spiral sections moving in opposite direction.

It is noted that conventional twin conveyor designs for air cooling/heating the items <NUM> may be adapted for use with liquid cooling/heating the items <NUM> according to the invention by placing the items <NUM> only onto the lower conveyor and using the upper conveyor for securing the same.

Referring to <FIG>, a spiral conveyor system for immersing items in a liquid <NUM> not according to the invention is provided. In the spiral conveyor system <NUM> the items <NUM> are secured to the conveyor <NUM> by generating a substantially downward oriented flow of the liquid <NUM> through the conveyer <NUM>, as indicated by the block arrows in <FIG>, thus gently pressing the items <NUM> onto the conveyor <NUM>.

Preferably, the spiral conveyor system <NUM> comprises spiral guiding structure <NUM> rotatable mounted to tank <NUM> via drive shaft 408A connected to drive 408B for guiding/moving the conveyor <NUM> from entry section <NUM> in a downward direction to cross-over section <NUM> and spiral guiding structure <NUM> rotatable mounted to tank <NUM> via drive shaft 410A connected to drive 410B for guiding/moving the conveyor <NUM> in an upward direction from the cross-over section <NUM> to exit section <NUM>.

Referring to <FIG>, the conveyor <NUM> comprises conveyor bottom 406A - supported by guide rails <NUM> of the respective spiral guiding structure <NUM>, <NUM> - and walls 406B. Preferably, the conveyor bottom 406A comprises a lattice structure - made of, for example, metal such as stainless steel, or plastic such as nylon - for supporting the items <NUM> placed thereupon while also providing sufficient open area <NUM> for allowing sufficient liquid flow therethrough. Other structures may be employed as long as sufficient open area <NUM> can be provided. The waterflow is guided in the downward direction by placing the conveyor <NUM> between cylindrical walls <NUM>, <NUM> surrounding the same in close proximity, with the wall <NUM> mounted to the respective spiral guiding structure <NUM>, <NUM> and the wall <NUM> mounted to the tank <NUM>.

Alternatively, the walls 406B of the conveyor <NUM> are overlapping solid plates and have sufficient height for guiding the liquid flow, or the walls 406B of a self-stacking conveyor are overlapping solid plates, as illustrated in <FIG>.

Further alternatively, baffles <NUM> are placed in proximity to the conveyor <NUM>, as illustrated in <FIG>. For example, the baffles <NUM> comprise flat plates placed around the conveyor <NUM> or ring structures surrounding the conveyor <NUM>. The baffles <NUM> are oriented downwardly substantially vertical or angled towards the conveyor <NUM>.

It is noted that walls or baffles may also be placed in proximity to the conveyor <NUM> at the cross-over section <NUM>.

The substantially downward oriented flow of the liquid <NUM> through the conveyer <NUM> is, preferably, generated using a liquid input structure placed above the conveyor for providing the liquid <NUM> and a liquid output structure placed below the conveyor in close proximity thereto for removing the liquid <NUM>. The liquid input structure comprises, for example, liquid input annulus 412A placed above the conveyor <NUM> surrounding the spiral guiding structure <NUM> and liquid input annulus 414A placed above the conveyor <NUM> surrounding the spiral guiding structure <NUM>. The liquid input annuli 412A, 414A are designed to receive the liquid <NUM> from respective liquid input conduits 412B, 414B and to provide via a plurality of openings 412C, 414C a liquid flow that is substantially equally distributed over the respective annulus formed by the conveyor surrounding the spiral guiding structures <NUM>, <NUM>, as illustrated in <FIG>, <FIG>.

The liquid output structure comprises, for example, liquid output annulus 416A placed below the conveyor <NUM> surrounding the spiral guiding structure <NUM> and liquid output annulus 418A placed below the conveyor <NUM> surrounding the spiral guiding structure <NUM>. The liquid output annuli 412A, 414A are designed to remove the liquid <NUM> in a substantially equally distributed manner covering the respective annulus formed by the conveyor <NUM> surrounding the spiral guiding structures <NUM>, <NUM> via a plurality of suction openings 416C, 418C and to provide the removed liquid to respective liquid output conduits 416B, 418B, as illustrated in <FIG>, <FIG>.

Cross-over liquid output 420A connected to liquid output conduit 420B is placed below the conveyor <NUM> at cross-over section <NUM> for removing the liquid <NUM> from below the conveyor <NUM> in order to secure the items <NUM>, preferably spanning the entire length of the cross-over section <NUM>. Optionally, cross-over liquid input 430A connected to liquid input conduit 430B is placed above the conveyor <NUM> at cross-over section <NUM>, as indicated by the dashed lines in <FIG>.

The liquid flow is determined to be strong enough for sufficiently pressing the items <NUM> onto the conveyor <NUM> while being gently enough to not dislodge the items <NUM> from the conveyor <NUM>.

The liquid flows downward through the conveyor <NUM> stack due to the weight of the incoming liquid above and drawn by the suction from the outflow.

Preferably, the liquid output annuli 416A, 418A and the cross-over liquid output 420A are placed a predetermined distance above a bottom wall of the tank <NUM> to prevent debris and particulates accumulated at the bottom of the tank <NUM> from being sucked into the output conduits 416B, 418B, and 420B. Further preferably, the bottom wall 402A of the tank <NUM> is sloped at an angle α towards drain port <NUM>, allowing draining of the debris and particulates accumulated at the bottom of the tank <NUM>.

The spiral conveyor system <NUM> comprises a liquid return connecting the liquid output conduits 416B, 418B, and 420B with the liquid input conduits 412B, 414B, and (optionally) 430B. The liquid return comprises a liquid heating/cooling apparatus <NUM> such as, for example, a heat exchanger containing a heat source or cooling source such as hot water, steam, ammonia, CO<NUM>, Freon for adjusting the temperature of the liquid <NUM>, a pump <NUM> for pumping the water to the liquid input conduits, and flow control valve <NUM> for controlling the liquid flow.

The present invention has been described herein with regard to preferred embodiments.

Claim 1:
A spiral conveyor system comprising:
a tank (<NUM>) for containing a liquid (<NUM>) at a predetermined temperature therein;
a conveyor (<NUM>) for conveying items (<NUM>) through the liquid;
a guiding structure (<NUM>, <NUM>) disposed in the tank for guiding the conveyor in a spiral-type fashion; and,
characterized in that the conveyor (<NUM>) is a self-stacking conveyor (106A) or a non-self-stacking conveyor (106B), the conveyor (106A, 106B) comprising side walls which, with a top side of the conveyor (106A, 106B) and a bottom side of a conveyor section of the conveyor stacked thereon, form an enclosure for securing the items therein while being conveyed through the liquid, and the side walls are stacked upon each other while being guided by the guiding structure to form a spiral (<NUM>, <NUM>),
wherein in the self-stacking conveyor (106A) the side walls are downward oriented or upward oriented, and
wherein in the non-self-stacking conveyor (106B) the side walls are downward oriented, and the non-self stacking conveyor (106B) comprises an inside edge and an outside edge, and wherein the guiding structure (<NUM>, <NUM>) comprises an inside support framework (108B. <NUM>, 110B.<NUM>) and an outside support framework (108B.<NUM>, 110B.<NUM>) adapted for carrying the inside edge and the outside edge, respectively.