PRODUCT OVERBLOW MANAGEMENT ASSEMBLY

BACKGROUND

In the food industry, fluidized bed freezers or “flow” freezers are commonly used for quickly freezing food products as individual pieces (known as Individual Quick Freezing or “IQF”). Fluidization can be used with products such as vegetables, fruits, berries, etc. Fluidization keeps solid particles floating in an upward direction in a flow of gas or liquid. In freezing, fluidization occurs when particles of a similar shape and size are subjected to an upward stream of low-temperature air. Using this technique, a product may be put in a trough provided with a plurality of small holes. The food products to be frozen may be transported on a perforated conveyor (such as a belt or a tray) that may define the trough. Cold air is forced upwardly through the perforated conveyor and product bed and makes the food product “fluidize” to form a bed of product.

A known issue with this freezer type is so called product overblow, which means that food product or parts thereof follow the airstream out of the product zone. The overblown product can present at least two problems: (1) the overblown product is lost from production, reducing the overall yield in the process; and (2) the overblown product may end up at unwanted locations in the freezer such as walkways, evaporator coils, etc.

With regard to the second problem, the overblown product may eventually cause blocking of airflow during freezing production. For instance, the evaporator coils are especially prone to being blocked by overblown product, which affects cooling capacity and airflow. Moreover, stopping production to defrost/clean the freezer limits the capacity of the freezer, which in turn leads to lost revenues for the producers. Further, the evaporator coils, which are prone to being blocked by overblown product, are difficult to clean, increasing down time. Frequent defrosting and/or cleaning also leads to increased maintenance costs.

To contain the fluidized bed on the conveyor, the freezer may include “tray sides” mounted on each side of the conveyor. In a product zone, the tray sides have an outward incline, gradually increasing the flow area for the circulated air. In theory, an increased flow area means a decreased air velocity, thereby reducing the tendency for food products/debris to follow the airstream out of the product zone. However, it has been found that the increased flow area does not actually reduce the air velocity. Rather, a recirculation zone forms in an upper portion of the freezer, and the upward air velocity is not reduced.

In a further attempt to reduce the air velocity and pressure resistance, the tray sides may include bottom openings extending along the side of the conveyor. If overblown product passes through the openings in the tray sides, it does not typically end up in a problematic location (e.g., the evaporator coils). However, such openings can lead to product yield loss, and the openings do not significantly reduce the upward air velocity.

Some freezer systems have been designed to include a more complicated airflow path between the conveyor and the evaporator coils such that the overblown product does not reach the coils. For instance, in the system shown and described in EP 2 261 583 A1, the air must flow downwardly along a side of an evaporator assembly before the air travels upwardly into the evaporator assembly. Any product particles or debris, as well as snow formed during production, deposits onto the freezer floor due to gravity and do not reach the evaporator coils. Such a solution does not address the issue of food product/debris leaving the product zone, but rather, it focuses on separating the overblown product from the airstream before it reaches the evaporator coils. Further such a solution can only be implemented on a larger freezer, such as a sequential defrost freezer (such as the FLoFREEZE® Sequential Defrost (SD) freezer from JBT Corporation), as it requires more space compared to a standard (non-SD) freezer because of the more complex flow path.

Accordingly, improved systems and methods for managing product overblow in a fluidized bed freezer or “flow” freezer or in other gas treatment techniques are desired.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In some aspects, the techniques described herein relate to a product overblow management assembly for a gas treatment system configured to treat a product by circulating treatment gas from a heat exchanger assembly through a product carrying unit, the product overblow management assembly including: a first deflector assembly configured to substantially prevent product from leaving a product treatment zone of the product carrying unit; and a second deflector assembly configured to substantially direct overblown product that has left the product treatment zone into an overblow landing area separate from the heat exchanger assembly.

In some aspects, the techniques described herein relate to a gas treatment system, including: a housing; a heat exchanger assembly; a gas circulation assembly for circulating treatment gas within the housing; a product carrying unit configured to support product to be treated with treatment gas circulated within the housing and upwardly through the product carrying unit; and a product overblow management assembly including: a first deflector assembly configured to substantially prevent product from leaving a product treatment zone of the product carrying unit; and a second deflector assembly configured to substantially direct overblown product that has left the product treatment zone into an overblow landing area separate from the heat exchanger assembly.

In some aspects, the techniques described herein relate to a method of managing product overblow for a gas treatment system configured to treat a product by circulating treatment gas from a heat exchanger assembly through a product carrying unit, the method including: circulating treatment gas from a heat exchanger toward the product carrying unit; substantially prevent product from leaving a product treatment zone of the product carrying unit; and substantially directing overblown product that has left the product treatment zone into an overblow landing area separate from the heat exchanger assembly. This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a first side isometric view of a product overblow management assembly formed in accordance with an exemplary embodiment of the present disclosure incorporated into an exemplary flow freezer.

FIG. 2 is a second side isometric view of the product overblow management assembly and exemplary flow freezer of FIG. 1.

FIG. 3 is a top isometric view of product overblow management assembly and exemplary flow freezer of FIG. 1.

FIG. 4 is a front isometric view of product overblow management assembly and exemplary flow freezer of FIG. 1.

FIG. 5 is a front elevation view of product overblow management assembly and exemplary flow freezer of FIG. 1.

FIG. 6 is a graphical image of a computational fluid dynamic (CFD) flow field simulation using the product overblow management assembly of FIG. 1 incorporated into the exemplary flow freezer of FIG. 1.

FIG. 7 is a graphical image of a CFD flow field simulation using a prior art product overblow management assembly incorporated into the exemplary flow freezer of FIG. 1.

FIG. 8 is a graphical image of a CFD product overblow simulation using the product overblow management assembly of FIG. 1 incorporated into the exemplary flow freezer of FIG. 1.

FIG. 9 is a graphical image of a CFD product overblow simulation using a prior art product overblow management assembly incorporated into the exemplary flow freezer of FIG. 1.

FIG. 10 is a table comparing product overblow data between the product overblow management assembly of FIG. 1 incorporated into the flow freezer of FIG. 1 and the prior art product overblow management assembly of FIG. 9 incorporated into the flow freezer of FIG. 1.

FIG. 11 is a flowchart depicting an exemplary method of managing product overblow for a gas treatment system.

DETAILED DESCRIPTION

Aspects of the present disclosure relate to improved systems and methods for managing product overblow in a gas treatment system (a “product overblow management assembly”), such as a fluidized bed freezer or “flow” freezer. Although the exemplary product overblow management assembly is shown and described with reference to a fluidized bed freezer, it should be appreciated that the product overblow management assembly described herein may be adapted for use with other gas treatment systems, such as drying applications, heating applications, etc.

In general, the product overblow management assembly is suitable for integration into gas treatment systems having a relatively small overall footprint, such as a standard (non-SD) freezer, compared to a larger system such as a sequential defrost freezer. However, the product overblow management assembly is versatile in that it is not limited to smaller systems. Rather, the product overblow management assembly may also be suitable for other types of systems and/or larger systems, such as a sequential defrost freezer.

Generally, the product overblow management assembly is configured to reduce or otherwise minimize product overblow (e.g., reduce the quantity of product leaving the product zone). Moreover, if product does leave the product zone, the product overblow management assembly is configured to minimize the amount of overblow ending up in undesired areas of the gas treatment system, such as the evaporator coils. Instead, the product overblow management assembly is configured to direct overblow into a safe location where it reasonably easy to remove during a cleaning process.

Product overblow assemblies may be designed to effectively minimize product overblow and prevent the overblow from reaching an undesired area, such as the evaporator coils. However, to be effective, a product overblow management assembly for a gas treatment system must also not significantly affect system (e.g., freezer) performance. The product overblow management assembly described herein is configured to minimize product overblow and prevent the overblow from reaching an undesired area while substantially maintaining system (e.g., freezer) performance. For instance, when using the product overblow management assembly described herein, air flow resistance of the gas treatment system is minimized. The air flow resistance caused by the product overblow management assembly is sufficiently low such that it does not limit the airflow of the gas treatment system; and therefore, it does not reduce freezer capacity more than marginally.

FIGS. 1-5 depict a product overblow management assembly 102 formed in accordance with an exemplary embodiment of the present disclosure incorporated into an exemplary gas treatment system, which is a flow freezer 104. Generally, the flow freezer 104 is configured to quickly and individually freeze food products (such as vegetables, fruits, berries, shellfish, etc.) using fluidization techniques. The product overblow management assembly 102 is configured to minimize the amount of products leaving a treatment or product zone of the flow freezer 104, and it also substantially prevents overblow from reaching evaporator coils of the freezer. At the same time, the product overblow management assembly 102 is versatile in its use and minimizes impact on freezer performance.

Aspects of the exemplary flow freezer 104 will first be described. As generally described above, a flow freezer quickly and individually treats food products to produce IQF products by keeping the food products floating in an upwardly directed flow of treatment medium, such as a gas or liquid. If gas is used, the treatment medium is preferably air, however other gases may also be used. For example, nitrogen or carbon dioxide may be used for treatment of sensitive products requiring treatment in a protected atmosphere.

The flow freezer 104 includes a product carrying unit 106 that extends substantially along a length of an interior compartment of the freezer for supporting product as it is treated with the treatment medium, defining a product treatment zone 108. The product carrying unit 106 may be any suitable configuration, such a tray(s), an elongated trough(s), and/or an endless conveyor belt(s) having perforations, openings, apertures, etc., through which upwardly directed flow of the treatment medium may pass as the product moves along the length of the freezer. The tray, trough, belt, etc., may be defined by any suitable material, such as stainless steel, mesh, rubber, plastic, etc., and any combination thereof. The perforation, holes, etc., defined in the product carrying unit 106 may be any suitable size, shape, and arrangement. By way of example, the openings may have a diameter of about four millimeters (4 mm) and the total open area of the tray, belt, etc., may be about 20%.

The product carrying unit 106 is configured to move product along the length of the interior compartment of the freezer as it is treated with the treatment medium. If the product carrying unit 106 is configured as a tray or an elongated trough, the products may be conveyed through the flow freezer 104 by providing the trough at a slight inclination. In addition or in the alternative, the product may be conveyed along the product carrying unit 106 by introducing asymmetric vibrations of the tray or trough in a manner well-known in the art.

In the depicted embodiment, the product carrying unit 106 is configured as first and second substantially coaxially aligned conveyor belts 110a and 110b (an “IQF track”). The first conveyor belt 110a may be at a level different from the second conveyor belt 110b to define a dual-zone fluidization product treatment zone 108, or two separate pressure chambers, to support different stages of fluidization such as crust-freezing and core-freezing.

An infeed assembly (not shown) may be positioned upstream of the first conveyor belt 110a for depositing untreated food product onto the belt, and a collection assembly or another assembly (e.g., a conveyor assembly for transportation to a further processing system) may be located downstream of the second conveyor belt 110b. A vibratory assembly (not shown) may be used with the product carrying unit 106 for ensuring even distribution of the food product being conveyed to support de-watering of the food product, etc.

The flow freezer 104 includes a gas treatment system 112 configured to cool and circulate cooled air within the freezer such that it flows upwardly through the product treatment zone 108 for treating the food product. In that regard, the gas treatment system 112 may include a heat exchanger assembly 114 and a gas circulation assembly 116. The heat exchanger assembly 114 may be any suitable assembly configured to cool air after it has passed through the product treatment zone 108 of the product carrying unit 106 such that it may be recirculated to the product treatment zone 108 for treatment of the continuous flow of product. In the depicted exemplary embodiment, the heat exchanger assembly 114 is a collection of suitable number of evaporator coils 118 (such as three coil assemblies, as shown) for providing cooled air flow upwardly through the product treatment zone along its length.

In the embodiment shown, the heat exchanger assembly 114 has a capacity to supply cooled air substantially along the length of the product treatment zone 108. In that regard, the heat exchanger assembly 114 supplies cool treatment gas to the product treatment zone 108 to create at least a partly fluidized product bed in the product treatment zone (see FIG. 6). By way of example, the temperature of the treatment gas fluidizing the product may be in the range of −20° C. to −35° C.

The gas circulation assembly 116 is configured to circulate cooled treatment gas (or simply hereinafter “air”) from the heat exchanger assembly 114, through the product treatment zone 108 of the product carrying unit 106, and back to the heat exchanger assembly 114 for cooling. In the depicted exemplary embodiment, the gas circulation assembly 116 is a collection of suitable number of fans 120 for circulating cooled air flow along the length of the product treatment zone and back to the heat exchanger assembly 114. In the embodiment shown, the gas circulation assembly 116 includes five evenly spaced fans 120 with one fan is “missing” in an axial location generally at the transition between the first conveyor belt 110a and the second conveyor belt 110b.

The gas treatment system 112 is optimally positioned within the flow freezer 104 by a support structure, such as a frame 122. The frame 122 or other support structure generally positions the evaporator coils 118 above the product treatment zone 108 and positions the fans 120 below the product treatment zone 108. In that regard, the evaporator coils 118 rest on a substantially horizontal platform 124 defined at a height substantially equal to or above a top surface of the product carrying unit 106 (such as a top surface of the first conveyor belt 110a). The substantially horizontal platform 124 also defines a horizontal partition within the interior of the flow freezer 104, substantially separating the cooled air leaving the evaporator coils 118 from the incoming warmed air.

The fans 120 are located in a substantially vertical partition 126 of the frame 122, which extends substantially transversely downwardly from the substantially horizontal platform 124 on the side of the frame 122 away from a freezer interior wall (toward the product carrying unit 106). The substantially vertical partition 126 is also positioned substantially transversely to the longitudinal axis of the product carrying unit 106 such that the fans 120 may be vertically located in the vertical partition to move air from a low-pressure zone 128 defined beneath the evaporator coils 118 to a high-pressure zone 130 defined beneath the product carrying unit 106. The fans 120 or other air movement devices of the gas circulation assembly 116 are selected to generally define air circulation within the freezer interior suitable for product treatment (e.g., fluidization). For instance, in the exemplary flow freezer 104, the fans 120 may have a capacity to produce an air volume flow of about 10-12 m³/s. It should be appreciated that for certain gas treatment systems or products that are being treated, the gas circulation assembly 116 may be increased or decreased in capacity to achieve needed air circulation characteristics.

With the evaporator coils 118 and the fans 120 arranged in the above-described configuration or in a similar configuration, air circulates within the interior of the flow freezer 104 in a circular manner. More specifically, the air flows downwardly through the evaporator coils 118, where warm air is cooled. The cooled air is drawn downwardly into the low-pressure zone 128 beneath the evaporator coils 118 and then substantially transversely into the high-pressure zone 130 past the fans 120. Cooled air is drawn substantially upwardly through openings in the product carrying unit 106 through the product treatment zone 108 of the product carrying unit 106. After leaving the product treatment zone 108, the warmed air (caused by heat exchange between the air and the fluidized product) moves substantially transversely across an upper interior of the flow freezer 104 (not shown) and thereafter substantially downwardly into the heat exchanger assembly 114 for cooling.

By circulating air in the above-described manner, food product is effectively fluidized as it moves along the product carrying unit 106 in the product treatment zone 108. Fluidization may be improved by introducing vibration, e.g. by pulsating the air or by vibration of the product carrying unit 106. In that regard, the gas treatment system 112 may further include a pulsator assembly (not shown) and a bypass assembly for controlling airflow through the product treatment zone 108.

A pulsator assembly and/or a bypass assembly 154 may be defined at least in part by an air-tight door, a damper, a vent or a valve (such as vent 156), a hood or hatch (such as hatch 158), etc. (a “pulsator” or a “bypass mechanism”). Each pulsator of the pulsator assembly (not shown) may be selectively opened to allow a leakage of treatment gas from the high-pressure zone 130 into the area between the product carrying unit 106 and the heat exchanger assembly 114 (e.g., the overblow landing area 146, described below). By quickly closing an opened pulsator, the pressure in the high-pressure zone 130 may be increased, thereby creating a “pulse” of gas through the openings of the product carrying unit 106. The pulsators may be used to facilitate the start-up of the fluidization of the products. Each pulsator may be opened and closed separately from other components, such as with the use of a controllable actuator.

The bypass mechanisms of the bypass assembly 154 (which may include hoods, vents, etc. located in a second overblow landing assembly plate 150 or in another portion of the overblow landing area 146, described below) may be used to further control airflow through the flow freezer 104. For instance, the bypass mechanisms may be used to lower the airflow velocity through the product carrying unit 106 to fine tune the amount of fluidization of the product bed.

Referring to FIGS. 1-5, an exemplary embodiment of the product overblow management assembly 102 will now be described in more detail. As noted above, the product overblow management assembly 102 is configured to reduce or otherwise minimize product overblow (e.g., reduce the quantity of product leaving the product zone 108). Moreover, if product does leave the product zone 108, the product overblow management assembly is configured to minimize the amount of overblow ending up in undesired areas of the gas treatment system 112, such as the evaporator coils 118. Instead, the product overblow management assembly 102 is configured to direct overblow into a safe location where it is reasonably easy to remove during a cleaning process.

A computational fluid dynamics (CFD) simulation was performed to evaluate the product overblow management assembly 102, such as by comparing the product overblow management assembly 102 to a prior art assembly used on a substantially similar flow freezer. The CFD simulations of the product overblow management assembly 102 are shown in FIG. 6 (flow field) and FIG. 8 (particle tracking), and comparison CFD simulations of the prior art assembly are shown in FIG. 7 (flow field) and FIG. 9 (particle tracking). Reference to the CFD simulations will be made when describing certain aspects of the product overblow management assembly 102 below.

In the exemplary depicted embodiment, the product overblow management assembly 102 is generally defined by deflector assemblies having deflectors that are suitably shaped, sized, and arranged to substantially prevent product from leaving the product treatment zone 108. Further, the deflector configuration is optimized to direct overblown product towards an overblow landing area 146 defined between the product carrying unit 106 and the heat exchanger assembly 114. In this manner, the product overblow can be easily removed during cleaning (as opposed to when product overblow lands on the evaporator coils 118).

Before discussing the particular embodiment shown, it should be appreciated that any suitable configuration and arrangement of deflectors may be used for achieving the desired result of substantially preventing product from leaving the product treatment zone and directing any overblown product towards an overblow landing assembly or another area that is easy to clean (e.g., away from the evaporator coils). For instance, the deflectors may be lengthened, shortened, or otherwise adjusted in size to accommodate a larger or smaller gas treatment system or a gas treatment system having a different capacity. Further, if the overblow landing assembly is defined in another area of the gas treatment system, it should be appreciated that the deflector configuration, size, and/or arrangement may be adapted to direct air towards that overblow landing assembly. Accordingly, although a preferred exemplary embodiment is described herein, the product overblow management assembly 102 may be adapted for integration into other gas treatment systems.

The product overblow management assembly 102 includes a first deflector assembly that includes first and second tray side assemblies defined on first and second sides of the product carrying unit 106, respectively, wherein the first side of the product carrying unit 106 is furthest from the heat exchanger assembly 114. Openings along the side of the product carrying unit 106 (e.g., at the intersection of the belt and the tray side) are not included. However, it should be appreciated that in some embodiments, such as in gas treatment systems having smaller or larger capacity, openings may be included.

The first tray side assembly includes a substantially vertical first tray side 132 extending upwardly from the top surface of the product carrying unit 106 for substantially preventing product from leaving the first side of the product carrying unit 106 during processing. A first tray side extender 134 extends upwardly and outwardly from the first tray side 132, such as at about a forty-five degree angle (45°). The first tray side 132 and the first tray side extender 134 may be similar to prior art tray side designs seeing as it is located on the first side of the product carrying unit 106 furthest from the heat exchanger assembly 114. Accordingly, product overblow leaving the first side of the product carrying unit 106 will not fall onto the heat exchanger assembly 114. In that regard, the first tray side 132 and first tray side extender 134 may not necessarily be considered part of the product overblow management assembly 102 but useful for maintaining product in the product treatment zone 108.

A second tray side assembly on the second side of the product carrying unit 106 opposite the first side (closest to the heat exchanger assembly 114) is generally configured to direct air upwardly away from the product treatment zone 108 and away from the heat exchanger assembly 114. In that regard, the second tray side assembly includes a substantially vertical second tray side 136 that extends upwardly from the top surface of the product carrying unit 106 for substantially preventing product from leaving the second side of the product carrying unit 106 during processing and directing air upwards. The second tray side 136 may be substantially the same height as the first tray side 132, thereby defining a substantially rectangular product treatment zone 108 above the top surface of the product carrying unit 106 (e.g., the top surface of the conveyor belt, as shown in FIG. 7, where the product treatment zone 108 generally defines a substantially rectangular “product bed”).

The second tray side assembly further includes a second tray side extender 138 extending upwardly and generally inwardly from the second tray side 136 toward a center longitudinal axis of the product carrying unit 106. The second tray side extender 138 extends upwardly and inwardly from the second tray side 136 to direct the upwardly flow of air generally away from the heat exchanger assembly 114. For instance, the inwardly extending second tray side extender 138 may be offset from vertical about ten to twenty degrees (10-20°). The angle may be increased or decreased depending on various factors, such as the width of the product carrying unit 106, the horizontal and/or vertical distance of the product carrying unit 106 from the heat exchanger assembly 114, the air flow velocity through the product carrying unit 106, etc. In the embodiment shown, the inwardly extending second tray side extender 138 may be offset from vertical between about twelve to seventeen degrees (12-17°), such as about fifteen degrees (15°).

The inwardly extending second tray side extender 138 is also of a height such that it forces airflow travel up and over a top end of the second tray side extender 138 before traveling toward the heat exchanger assembly 114 for heat exchange, as shown in FIG. 6. In the depicted embodiment, the top end of the second tray side extender 138 is generally located above the top surface of the heat exchanger assembly 114. The height of the second tray side extender 138 may be increased or decreased depending on various factors, such as the width of the product carrying unit 106, the horizontal and/or vertical distance of the product carrying unit 106 from the heat exchanger assembly 114, the air flow velocity through the product carrying unit 106, etc.

As noted above, the bypass mechanisms may be used to lower the airflow velocity through the product carrying unit 106 to fine tune the amount of fluidization of the product bed. In some embodiments, the bypass mechanisms may be selectively opened to lower the air flow velocity through the product carrying unit 106 to decrease or otherwise minimize the amount of product overblow. In other words, with a lower air velocity through the product carrying unit 106, any products leaving the product treatment zone 108 may necessarily have a lower velocity and may not reach the top end of the second tray side extender 138. Of course, any airflow adjustment is also balanced with freezer performance.

The combination of the height and inward angle of the second tray side extender 138 substantially prevents product from leaving the product treatment zone 108 (wherein the product treatment zone 108 may be understood to include the area in which the product bed forms and the area extending upwardly from the product bed). Accordingly, using the product overblow management assembly 102 having features described herein, product overblow is minimized. At the same time, the height and inward angle of the second tray side extender 138 does not significantly impede air flow throughout the freezer. As can be appreciated, if a significantly greater inward angle was used for the second tray side extender 138, product overblow may be eliminated entirely, but air flow resistance would increase and significantly impact freezer performance. Accordingly, the angle of the second tray side extender 138 is selected to minimize product overblow while minimizing air flow resistance as the air flows toward the heat exchanger assembly 114.

Air flows up and over the second tray side extender 138 towards the heat exchanger assembly 114 for cooling, as shown in FIG. 6. In some instances, treated product will travel with the air up and over the top end of the second tray side extender 138, resulting in product overblow. In that regard, the product overblow management assembly 102 further includes a second deflector assembly, or an overblow landing assembly (not separately labeled) configured to substantially direct overblown product toward a desired area of the flow freezer 104 that is easy to clean (e.g., away from the evaporator coils 118 of the heat exchanger assembly 114), such as an overblow landing area 146.

In one aspect, the overblow landing assembly includes a resistance guide 139 defined at the top end of the second tray side extender 138 to help reduce resistance of air flowing up and over the top end of the second tray side extender 138, as shown in by the air flow velocity area 160 in FIG. 6. The resistance guide 139 may be a generally curved configuration to guide air up and over the top of the second tray side extender 138 as it travels toward the heat exchanger assembly 114. In the depicted exemplary embodiment, the resistance guide 139 is defined by a first flow resistance guide plate 140 extending generally upwardly and away from the second tray side extender 138 and a second flow resistance guide plate 142 extending generally laterally or horizontally from the first flow resistance guide plate 140. The first flow resistance guide plate 140 may extend away from the second tray side extender 138 (toward the heat exchanger assembly 114) at an angle between about thirty to fifty-five degrees (30-55°), such as about forty-five degrees (45°).

The first flow resistance guide plate 140 and second flow resistance guide plate 142 may be generally about the same length such that an upper tip of the second tray side assembly is substantially aligned with the second side of the product carrying unit 106, or slightly offset toward the heat exchanger assembly 114 from the second side of the product carrying unit 106. The length of the first flow resistance guide plate 140 and/or the second flow resistance guide plate 142 may of course be adjusted to accommodate a smaller or larger distance between the product carrying unit 106 and the heat exchanger assembly 114, air flow changes, etc. Further, it should be appreciated that in some embodiments, the resistance guide 139 may instead be defined by a continuously curved surface or another suitable contour.

In another aspect, the overblow landing assembly includes a redirection plate 144 configured to generally direct air and any overblown product flowing laterally over the resistance guide 139 generally downwardly toward the overblow landing area 146 defined between the product carrying unit 106 and the heat exchanger assembly 114. The redirection plate 144 is generally a vertically oriented plate extending downwardly from an interior surface of the ceiling of the flow freezer 104, thereby defining a partial vertical partition in the freezer.

The redirection plate 144 is located generally about half-way between the horizontal location of the product carrying unit 106 and the horizontal location of the heat exchanger assembly 114. Moreover, the redirection plate 144 extends downwardly from the ceiling interior surface a predetermined distance. In the depicted exemplary embodiment, the redirection plate 144 extends downwardly from the freezer ceiling such that a vertical location of the lower or distal tip of the redirection plate 144 is located generally equidistant from the distal end of the second flow resistance guide plate 142 and the top of the heat exchanger assembly 114. Of course, the length of the redirection plate 144 may be shorter or longer depending on various factors, such as the overall height of the freezer, the location of the heat exchanger assembly 114 relative to the product carrying unit 106, the air velocity through the freezer, etc.

The location and length of the redirection plate 144 is designed such that air flowing generally laterally across the resistance guide 139 flows downwardly around the distal tip of the redirection plate 144 before flowing generally upwardly toward the heat exchanger assembly 114, as shown in FIG. 6. In that regard, the redirection plate 144 generally changes the direction of the air, turning the airflow approximately ninety degrees (90°) as it flows from the product carrying unit 106 to the heat exchanger assembly 114. More specifically, as the air passes over the resistance guide 139 and encounters the redirection plate 144, the air flows downwardly along the length of the redirection plate 144 until it reaches the distal end of the redirection plate 144. When the air reaches the distal end of the redirection plate 144, the air flow direction changes, turning approximately ninety degrees (90°) towards the heat exchanger assembly 114.

As the air flow direction changes, the velocity of the air flowing adjacent to and/or close to the redirection plate 144 increases (as shown in high velocity air 162 of FIG. 6), whereas air flowing beneath high velocity air 162 remains lower in air velocity (as shown in low velocity air 164 of FIG. 6). Such a turn in airflow and increase in velocity in the high velocity air 162 helps separate any product overblow from the air stream (which flows to the heat exchanger assembly 114) and directs the overblow toward the overblow landing area 146 (see the arrow in FIG. 6 as well as the particle areas 170 and 172 shown in FIG. 8). Further, the redirection plate 144 physically prevents the overblown product from continuing in a lateral trajectory toward the heat exchanger assembly 114, disrupting its momentum and allowing it to fall downwardly into the stream of low velocity air 164 and thereafter toward the overblow landing area 146.

The configuration of the overblow landing assembly (e.g., the redirection plate 144 in its relation to the second tray side extender 138 and the resistance guide 139) redirects the air flow and increases velocity for product overblow separation without causing significant air flow resistance that would impact freezer performance. For instance, through testing and CFD simulation, the inventors found that the total pressure loss caused by the product overblow management assembly 102 is about one hundred Pascal (100 Pa), where the total air pressure drop in the exemplary fluidized bed freezer is typically in the range of about nine hundred to nineteen hundred Pascal (900 Pa to 1900 Pa), depending on product bed thickness, the amount of frost buildup on the evaporator coils or conveyor, etc. Accordingly, the product overblow management assembly 102, including the overblow landing assembly, does not cause significant air resistance and therefore does not significantly impact freezer performance.

As noted above, the overblow landing area 146 may be defined between the product carrying unit 106 and the heat exchanger assembly 114. The overblow landing area 146 may be defined by any suitable structure extending between the product carrying unit 106 and the heat exchanger assembly 114. For instance, in the depicted exemplary embodiment, the overblow landing area 146 is defined by a first overblow landing assembly plate 148 extending substantially transversely and slightly downwardly from the second tray side extender 138, a second overblow landing assembly plate 150 extending substantially transversely and downwardly from the first overblow landing assembly plate 148, and a third overblow landing assembly plate 152 extending substantially transversely and slightly downwardly from the second overblow landing assembly plate 150 until it intersects the substantially horizontal platform 124 of the heat exchanger frame 122.

As can be appreciated from the foregoing, and referring to FIGS. 6 and 8, the product overblow management assembly 102 substantially prevents product from leaving the product treatment zone 108. Further, the product overblow management assembly 102 is optimized to direct overblown product towards an overblow landing area 146 that is away from the evaporator coils 118. Moreover, the product overblow management assembly 102 reduces product overblow and directs any overblow to a safe area without significantly impacting freezer performance.

By comparison, in the prior art design shown in the CFD simulations of FIGS. 7 and 9 (where like parts are labeled with like reference numerals except in the '200 series), a significant amount of product leaves the product treatment zone 208, and a significant amount of the overblown product ends up on the evaporator coils 218. The prior art overblow assembly generally includes an outwardly inclined middle plate 240 located above and spaced from a second tray side extender 238. The outwardly inclined middle plate 240 includes a lower transverse flange 242 (having a downwardly turned lip 246) and an upper transverse flange 248. A vertical partition 244 extends downwardly from the freezer ceiling toward the upper end of the outwardly inclined middle plate 240. First and second airflow openings are therefore defined between a first overblow landing assembly plate 249 extending substantially transversely and downwardly from the second tray side extender 238 and the lower transverse flange 242 as well as between the second tray side extender 238 and the vertical partition 244. The air flows through the first and second openings, allowing product to leave the product treatment zone 208 and reach the evaporator coils 218.

The boundary conditions for the CFD simulations, including the flow field comparisons and the particle tracking were generally as follows:

- Each evaporator coil was replaced by an outlet condition.
- The vents, hatches, etc., of the bypass/pulsator assembly were replaced by inlets to enable a steady-state approach.
- The product carrying unit and the food product on top of the product carrying unit were replaced by a region with a momentum loss to mimic the loss of pressure experienced by cold air running through the product carrying unit.

The inputs for the CFD simulations were generally as follows:

- Air volume flow total: 10.8 m³/s per fan (54 m³/s total) (velocity specified on all five fans and bypass hatches/pulsators).
- Bypass flow: 20% (10.8 m³/s total), distributed evenly across bypass hatches and pulsators.
- Outlet pressure specified on all outlets (evaporator coils).
- Air volume flow through belt/Average velocity:
  - Zone 1 (first conveyor belt 110a): 3.68 m/s.
  - Zone 2 (second conveyor belt 110b): 3.57 m/s.
- Pressure drop over first and second conveyor belts 110a and 110b and food product bed: ˜ 600 Pa @ 1.2 kg/m³.
- Air is treated as incompressible and isothermal (−20° C.).
- Two equations turbulence model k-w SST.
- Gravity affects the trajectory of the particle.
- Momentum loss (porous region) in the lateral regions surrounding the belts.

Example

A CFD analysis with particle tracking was carried out for the product overblow management assembly 102 and the prior art design, wherein the results set forth in the table of FIG. 10. In the table of FIG. 10, the “New Geometry” refers to the product overblow management assembly 102, whereas the “Current Geometry” refers to the prior art overblow assembly design shown in FIGS. 7 and 9. The selected product/particle for the analysis were peas/peels. It was assumed that each pea has a spherical shape with a constant diameter and density. In that regard, the drag was assumed for that of a sphere, which depends exclusively on the diameter. The possibility of multiple peas being frozen together was modeled by calculating the diameter of a sphere with the total volume of multiple peas. Groups up to four peas were tested.

The simulation included releasing peas from the top surface of the belt (sent into the air by the air flow), modeled using lagrangian particle tracking. As the conditions that allow some of the peas to fly were unknown, different parameters were tested (e.g., different velocity magnitudes and directions). The possibility of partially broken peas was modeled assuming the same diameter and volume but a lower density (a broken pea thus possessed the same drag but lower weight). Peas having a density of 40% and 20% of a reference pea were tested.

The possibility of the shell of the pea flying without the core was modeled by calculating the thickness of the peel (0.05 mm), its weight (assuming the same density as that of the pea) and its surface area. The diameter was also adjusted to account for the real surface of the entire peel, and the possibility that the peel would split in two was also considered.

It was assumed that particles interacting with the walls/plates/defectors do not bounce (100% restitution coefficient) but they lose substantially all their kinetic energy (about 95%). Such an assumption allows the flow to accelerate the particles again in a direction that might allow them to reach the evaporator coils.

The analysis includes four tests (#4, #3, #2, and #1), with each test representing different initial velocities for the particles in both a vertical and axial (lateral) direction. For instance, for test #4, the initial velocity for the particle in a vertical direction was 8 m/s, and the initial velocity for the particle in an axial direction was 2 m/s. For each test, the simulation results show whether the particle (one pea, pea of 40% density of one pea, pea of 20% density of one pea, a single peel, and a double peel) escaped the product treatment zone (“made the jump and landed safely”) and if so, whether the particle reached the evaporator coils (“arrived at the cooling batteries region”).

As can be seen by the results shown in the table of FIG. 10, for the product overblow management assembly 102 described herein, a significantly lower number of particles left the product treatment zone compared to the prior art design. Moreover, of the particles that left the product treatment zone, none of the particles reached the evaporator coils. By comparison, in the prior art design, a significant number of particles left the product treatment zone and reached the evaporator coils 118.

Exemplary Method

FIG. 11 is a flowchart of an example method 1100 for managing product overblow for a gas treatment system that is configured to treat a product by circulating treatment gas from a heat exchanger assembly through a product carrying unit. The method 1100 may be carried out using the product overblow management assembly 102 described herein incorporated into a suitable gas treatment system, such as the flow freezer 104.

At step 1110, the method 1100 includes circulating treatment gas from a heat exchanger toward the product carrying unit. For instance, treatment gas may be circulated in the flow freezer 104 from the heat exchanger assembly 114 toward the product carrying unit 106.

At step 1120, the method 1100 includes substantially preventing product from leaving a product treatment zone of the product carrying unit. For instance, the first deflector assembly, including the second tray side extender 138, may be used to substantially prevent product from leaving the product treatment zone 108 of the product carrying unit 106.

At step 1130, the method 1100 includes substantially directing overblown product that has left the product treatment zone into an overblow landing area separate from the heat exchanger assembly. For instance, the second deflector assembly, including the redirection plate 144, may be used to substantially direct overblown product that has left the product treatment zone 108 into the overblow landing area 146 separate from the heat exchanger assembly 114.

In one aspect, the method 1100 may include directing airflow upwardly away from the product treatment zone of the product carrying unit and inwardly toward a center longitudinal axis of the product carrying unit to substantially prevent product from leaving a product treatment zone of the product carrying unit. For instance, the second tray side extender 138 may be used to direct airflow upwardly away from the product treatment zone 108 of the product carrying unit 106 and inwardly toward a center longitudinal axis of the product carrying unit to substantially prevent product from leaving the product treatment zone.

In one aspect, the method 1100 may include redirecting airflow leaving the product treatment zone of the product carrying unit substantially downwardly toward the overblow landing area. For instance, the redirection plate 144 may redirect airflow leaving the product treatment zone 108 of the product carrying unit 106 substantially downwardly toward the overblow landing area 146.

In one aspect, the method 1100 may include increasing the airflow velocity as the airflow is redirected. For instance, as the air passes over the redirection plate 144 and the air flow direction changes, the velocity of the air flowing adjacent to and/or close to the redirection plate 144 increases (as shown in high velocity air 162 of FIG. 6), whereas air flowing beneath high velocity air 162 remains lower in air velocity (as shown in low velocity air 164 of FIG. 6). Such a turn in airflow and increase in velocity in the high velocity air 162 helps separate any product overblow from the air stream (which flows to the heat exchanger assembly 114) and directs the overblow toward the overblow landing area 146 (see the arrow in FIG. 6 as well as the particle areas 170 and 172 shown in FIG. 8).

In one aspect, the method 1100 may include selectively opening at least one of a bypass mechanism and a pulsator. In one aspect, the method 1100 may include selectively opening a bypass mechanism to adjust treatment gas velocity through the product carrying unit. For instance, a bypass mechanism(s) may be opened to lower the airflow velocity through the product carrying unit 106 to fine tune the amount of fluidization of the product bed.

In one aspect, the method 1100 may include minimizing a pressure loss in the gas treatment system within about one hundred Pascal (100 Pa). For instance, using the product overblow management assembly 102 described herein for a flow freezer 104 or a similar gas treatment system, product overblow is managed while only increasing pressure loss for the gas treatment system within about one hundred Pascal (100 Pa).

Various example embodiments of the disclosure are discussed in detail above. While specific implementations are discussed, it should be understood that this description is for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. Thus, the description and drawings are illustrative and are not to be construed as limiting.

Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. References to one or an embodiment in the present disclosure can be references to the same embodiment or any embodiment; and, such references mean at least one of the example embodiments.

Reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative example embodiments mutually exclusive of other example embodiments. Moreover, various features are described which may be exhibited by some example embodiments and not by others. Any feature of one example can be integrated with or used with any other feature of any other example.

The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Alternative language and synonyms may be used for any one or more of the terms discussed herein, and no special significance should be placed upon whether or not a term is elaborated or discussed herein. In some cases, synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms.

The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and is not intended to further limit the scope and meaning of the disclosure or of any example term. Likewise, the disclosure is not limited to various example embodiments given in this specification.

Without intent to limit the scope of the disclosure, examples of instruments, apparatus, methods and their related results according to the example embodiments of the present disclosure are given. Note that titles or subtitles may be used in the examples for convenience of a reader, which in no way should limit the scope of the disclosure. Unless otherwise defined, technical and scientific terms used herein have the meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document, including definitions will control.

Additional features and advantages of the disclosure are set forth in the description, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles. The features and advantages of the disclosure can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.

For clarity of explanation, in some instances the present technology may be presented as including individual functional blocks representing devices, device components, steps or routines in a method embodied in software, or combinations of hardware and software.

In the drawings, some structural or method features may be shown in specific arrangements and/or orderings. However, it should be appreciated that such specific arrangements and/or orderings may not be required. Rather, in some embodiments, such features may be arranged in a different manner and/or order than shown in the illustrative figures. Additionally, the inclusion of a structural or method feature in a particular figure is not meant to imply that such feature is required in all embodiments and, in some embodiments, it may not be included or may be combined with other features.

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are described herein in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives consistent with the present disclosure and the appended claims.

While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

PRODUCT OVERBLOW MANAGEMENT ASSEMBLY

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