Low-profile design air tunnel system and method for providing uniform air flow in refractance window dryer

Abstract

To disclose a low-profile design air tunnel system and a method for providing uniform air flow in a refractance window dryer.SOLUTION: According to one embodiment, the system comprises a conditioned air supply manifold that provides air into a drying chamber. The system has a drying belt directed through the drying chamber. A feed application tray at a first end of the drying belt applies a liquid to the drying belt. The system has an exhaust manifold located at the first end of the drying belt.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 751,273, filed October 26, 2018, and entitled “SLIM DESIGN AIR TUNNEL SYSTEM AND METHOD FOR PROVIDING UNIFORM AIR FLOW IN A REFRACTION WINDOW DRYER,” which is incorporated herein by reference.

[0002] [Technical field] The present disclosure relates generally to drying products. In particular, the present disclosure is directed to a molded air tunnel system and method for providing uniform airflow in a reflectance window dryer. [Background technology]

[0003] In a conventional drying system, the product to be dried is placed on a continuous belt that floats on the surface of a body of warm water. Heat is transferred by conduction directly from the circulating warm water through the polymer membrane belt to the product. The warm water is maintained at a predetermined temperature to allow optimal drying of the product.

[0004] However, conventional drying systems use large amounts of ambient air to remove water vapor released during the product drying process. Uncontrolled humidity and temperature of the ambient air within the dryer can result in wide variations in dryer efficiency and product quality. For example, a dryer operating in a dry climate will perform differently than in a humid climate. Similarly, dryer operation will vary in cold and tropical climates, and from season to season or day to night in the same location.

[0005] Additionally, conventional drying systems increase the water vapor pressure of the product by increasing the product temperature due to thermal energy conducted from the body of warm water through the dryer belt, but conventional drying systems do not reduce the water vapor pressure, increase the air temperature within the dryer, or reduce the humidity within the dryer, any of which would improve the efficiency of the dryer.

[0006] In conventional dual chamber drying systems, in both thick and thin designs, the product is dried on a continuous belt using a cross air flow technique with and without conditioned air introduced at regular intervals along one side of the belt, with an exhaust mechanism on the other side. Such designs promote short circuiting of the air and ineffectively use all the moisture that the short circuited air volume carries. Thus, the designs fail to efficiently distribute air across the width of the belt.

[0007] Another problem with previous designs was that the cross-flow across the belt did not fully utilize the heat available from the evaporating water from the product on the belt, resulting in the need for significant additional air. The original high hood design of the dryer system also resulted in the air flowing freely high above the belt surface, and the temperature rise was not fully utilized, especially at higher CFM flow rates. DISCLOSURE OF THEINVENTION

[0008] A low profile design air tunnel system and method for providing uniform airflow in a refractance window dryer is disclosed. According to one embodiment, the system includes a conditioned air supply manifold that supplies air to a drying chamber. The system includes a dryer belt oriented through the drying chamber. A supply application tray at a first end of the dryer belt applies liquid to the dryer belt. The system includes an exhaust manifold located at the first end of the dryer belt.

[0009] The above and other preferred features, including various novel details of implementation and combinations of elements, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the specific methods and devices are shown by way of illustration only and not by way of limitation. Those skilled in the art will appreciate that the principles and features described herein can be employed in various and numerous embodiments. [Brief description of the drawings]

[0010] The present invention will become more apparent upon consideration of the attached drawings and the accompanying detailed description. The embodiments illustrated therein are provided by way of example and not by way of limitation, and like reference numbers or characters generally refer to the same or similar elements, although in different drawings the same or similar elements may be referred to by different reference numbers or characters. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating aspects of the present invention.

[0011] [Figure 1] FIG. 1 illustrates a cross-sectional view of an exemplary dryer that uses an air supply manifold that extends across the width of the dryer belt, according to one embodiment.

[0012] [Diagram 2] FIG. 2 illustrates an exemplary dryer air supply manifold for distributing conditioned air according to one embodiment.

[0013] [Diagram 3] FIG. 3 illustrates a dryer exhaust manifold according to one embodiment.

[0014] [Figure 4] FIG. 4 illustrates an example side view of a conditioned air supply manifold, according to one embodiment.

[0015] [Diagram 5] FIG. 5 illustrates an example side view of a conditioned air supply manifold according to another embodiment.

[0016] [Figure 6] FIG. 6 shows a cross-sectional view of two drying chambers assembled to form a dual chamber dryer assembly according to one embodiment.

[0017] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. The disclosure should not be construed as limited to the particular forms disclosed, but on the contrary, the intent is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A low profile design air tunnel system and method for providing uniform airflow in a refractance window dryer is disclosed. According to one embodiment, the system includes a conditioned air supply manifold that supplies air to a drying chamber. The system includes a dryer belt oriented through the drying chamber. A supply application tray at a first end of the dryer belt applies liquid to the dryer belt. The system includes an exhaust manifold located at the first end of the dryer belt.

[0019] The following disclosure provides many alternative embodiments or examples for implementing different features of the present subject matter. Specific examples of components and arrangements are described below to simplify the disclosure. Of course, these are merely illustrative and are not intended to be limiting. Furthermore, the disclosure may repeat reference numerals or characters in many instances. This repetition is for simplicity and clarity and does not in itself affect the relationship between the various embodiments and / or configurations described.

[0020] Each of the features and teachings disclosed herein may be used separately or in combination with other features and teachings to provide a multi-chamber dryer with adjustable conditioned air flow in a low-profile air tunnel system. Representative examples of many of these additional features and teachings used separately or in combination are described in more detail with reference to the accompanying drawings. This detailed description is intended merely to teach those skilled in the art additional details for implementing the present teachings and is not intended to limit the scope of the claims. Thus, the combinations of features disclosed in the detailed description of the invention are not necessary to implement the present teachings in the broadest sense, but are presented only to specifically illustrate representative examples of the present teachings.

[0021] Other features and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of various embodiments.

[0022] A dual chamber dryer is disclosed that uses conditioned counter air flow that can be adjusted with a low profile air tunnel system. The drying system allows for the delivery of air flow that remains close to the belt / product surface taking full advantage of the heat gain and increased moisture capacity of air flowing against the belt / product flow. The drying system increases and improves dryer throughput in steady state operation. The drying system improves heat transfer by providing faster moisture removal from the product surface on the dryer belt, using a simplified and less expensive air handling system, and enhancing the quality of the dried product with more consistent drying characteristics. The components of the drying system described herein allow for a uniform supply of conditioned air across the width of the dryer belt and a low profile tunnel near the product surface evaporation area with constant air flow that creates a slight negative pressure with an exhaust fan, so that together the components allow for a more efficient and better performing drying system.

[0023] According to one embodiment, the apparatus includes a drying belt adapted to receive the product to be dried on a first side of the drying belt and a heating medium in contact with a second side of the drying belt. The heating medium is adapted to heat the product and maintain it at a predetermined temperature. The apparatus further includes a manifold located above the drying belt, the manifold including one or more slits for blowing conditioned air across the entire width of the drying belt and directed through the drying chamber towards an exhaust manifold at the location where the product is placed on the belt. Through this process, moisture evaporated from the product is removed, resulting in the formation of dry crystals. According to one embodiment, the conditioned air is air having a predetermined humidity and temperature. The humidity and temperature of the conditioned air may be specific to the type of product to be dried. In another embodiment, the air blown into the dryer is ambient air taken from the outside of the room or building in which the dryer is installed.

[0024] In the following description, for purposes of explanation only, specific terms are set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the work of the present disclosure.

[0025] The drying system, according to one embodiment, dries liquid or slurry products placed on a continuous drying belt by appropriately directing conditioned air across the product surface. The liquid or slurry may be of vegetable origin (e.g., strawberry puree, carrot puree, etc.). The drying system includes a series of air distribution manifolds that direct the conditioned air and devices that improve product delivery and product removal. In one embodiment, low pressure air is distributed through conditioned slots, or air knives, to efficiently distribute the air across the width of the drying belt. In another embodiment, the drying system has low profile side panels that allow airflow to remain close to the dryer belt, taking full advantage of the heat gained from moisture evaporation from the product on the dryer belt, while requiring less air than previous designs.

[0026] FIG. 1 illustrates a cutaway view of an exemplary dryer 100 that uses an air supply manifold 120 that extends across the width of a dryer belt 110, according to one embodiment. The dryer 100 includes a cover 101 that provides a cover and headspace over the dryer belt 110 of the dryer 100, an air supply manifold 120 that directs conditioned air 102 into the dryer 100, and an air outlet exhaust manifold 130. The dryer belt 110 floats on a heated medium that flows within a trough 150. The trough 150 may include a pump that circulates the heated medium between a heating tank and the trough 150. The heated medium may include hot water or other types of heat transfer fluids known in the art. The temperature of the hot water or other heat transfer fluid within the heated medium is maintained at a predetermined temperature. Although the dryer 100 includes one trough 150, multiple troughs may be used, each having an air supply manifold 120 and an exhaust manifold 130. In alternative embodiments, multiple channels may share a single air supply manifold 120 and exhaust manifold 130. According to one embodiment, dryer 100 may be one chamber of a multi-chamber dryer. In a multi-chamber dryer system, a single dryer belt 110 effectively spans all of the drying chambers by doubling, tripling, etc. the length of dryer belt 110. Dryer belt 110 is guided by rollers (not shown) that move it in a continuous loop from one end of dryer 100 to the other.

[0027] According to one embodiment, a liquid or slurry product is applied to the dryer belt 110. A conditioned air supply manifold 120 extends across the width of the dryer belt 110, but introduces conditioned air 102 at the discharge end 111 of the belt where the dried product is removed from the dryer 100. An exhaust manifold 130 is located at the other end 112 of the dryer belt 110, near the supply liquid application tray 140, and moist air is removed through the dryer exhaust manifold 130, which extends across the width of the dryer belt 110. In one embodiment, the liquid or slurry product is dried as moist air is removed by the dryer exhaust manifold 130 at the beginning 112 of the belt 110. The conditioned air supply manifold 120 at the discharge end 111 of the dryer belt 110 provides the conditioned air 102. According to one embodiment, the temperature of the conditioned air 102 is increased by approximately 15° C. by the time it reaches the discharge end 111 of the dryer belt 110 due to heat provided by the evaporation of the heated liquid, increasing the moisture capacity of the air that can be absorbed. This reduces the air flow requirements by a factor of ten, to approximately 5,700-14,000 liters / minute (200-500 CFM). The dried material 190 is removed at the discharge end 111 of the dryer belt 110.

[0028] FIG. 2 shows an exemplary dryer air supply manifold 240 that distributes conditioned air, according to one embodiment. The dryer air supply manifold 240 distributes conditioned air 210 across the width of the dryer belt 220 at the discharge end of the dryer, according to one embodiment. The conditioned air supply manifold has a Y-shape, with an upper tube 201 introducing conditioned air 210 from a filtered air system 230, such as a HEPA system. The conditioned air 210 passes through lower tubes 202, 203, and the air is distributed across the width of the dryer belt 220. According to one embodiment, the lower tubes 202, 203 connect to horizontal manifolds 204, 205 that have sanitary caps that allow for clean-in-place (CIP) cleaning and easy disassembly. The horizontal manifolds 204, 205 include slits 206, 207 through which the conditioned air 210 is blown into the drying chamber 208. According to one embodiment, the horizontal manifolds 204, 205 each have three openings, each having a narrow oval shape. According to one embodiment, each opening of the slits 206, 207 is approximately one-sixth the width of the dryer belt 220. In another embodiment, the horizontal manifolds 204, 205 each have a single opening, each opening being approximately half the width of the dryer belt 220. In one embodiment, the horizontal manifold 204 has a length that is half the width of the dryer belt 220. The horizontal manifold 204 may have a diameter of approximately 15 cm (6 inches). In an alternative embodiment, the horizontal manifolds 204, 205 each may include a damper (not shown) to reduce the volume of the conditioned air 210 discharged through the slits 206, 207 into the drying chamber 208. The damper may also direct the air flow toward the dryer belt 220 or toward the cover 250.

[0029] Filtered air system 230 supplies conditioned air 210 to conditioned air supply manifold 200. According to one embodiment, filtered air system 230 is an HVAC unit manufactured by AAON, model number RN-025-3-0-EBDA, having a cooling capacity of 85,000 W (290 MBH) and a heating capacity of 96,000 W (328.1 MBH).

[0030] FIG. 3 shows a dryer exhaust manifold 300 according to one embodiment. The dryer exhaust manifold 300 is located at the beginning of the dryer belt 320 near the feed coating tray according to one embodiment. The dryer exhaust manifold 300 removes the moist air 310 throughout the length and width of the drying tunnel 321. The dryer exhaust manifold 300 has a rectangular opening 301 that takes in the moist air 310 and pulls it up through a tube 303 using an exhaust blower 340. According to one embodiment, the exhaust opening 301 has a width approximately equal to the width of the dryer belt 320. In another embodiment, the exhaust manifold 300 may include a damper (not shown) to reduce the volume of moist air 310 removed from the drying chamber. The exhaust blower 340 expels the moist air 310 to the atmosphere outside the dryer chamber.

[0031] According to one embodiment, the exhaust blower 340 is a GREENHECK model number CUBE-300XP-50, rated at 3 CFM (CFM) at 3.5 inches (8.9 cm) static pressure (SP) driven by a variable frequency drive (VDF) with a 3.68 kW (5 HP) variable speed rated motor. 3 / min "Belt Drive Upblast Centrifugal Roof Exhaust Fan". In one embodiment, the exhaust blower is oversized to create negative pressure within the drying tunnel, improving the evaporation efficiency and therefore the humidity efficiency of the removal of moist air 310.

[0032] FIG. 4 illustrates an example side view of a conditioned air supply manifold 400, according to one embodiment. Conditioned air supply manifold 400 has a circular body 410 having a diameter of 6 inches according to one embodiment. Conditioned air supply manifold 400 also includes a supply aperture 420 extending from circular body 410. Supply aperture 420 has upper and lower portions 430 and 435 that are parallel to one another. According to one embodiment, upper and lower portions 430 and 435 are spaced approximately 5 / 16 inches from the center of supply aperture 420 creating a 5 / 8 inch aperture 425. Upper and lower portions 430 and 435 may extend approximately 2 inches from circular body 410. The desired type of aperture in dryer air knife 400 will vary depending on the application, with circular cavities 410 being more efficient in some applications and other shapes of cavities such as hexagonal cavities being more efficient in other applications.

[0033] FIG. 5 illustrates an exemplary side view of a hexagonal conditioned air supply manifold 500, according to one embodiment. The conditioned air supply manifold 500 includes a hexagon 510 having a width of 6 inches, according to one embodiment. The hexagon 510 has six sides with angles between adjacent sides ranging from 120° to 132°, in some embodiments. The conditioned air supply manifold 500 also includes a supply aperture 520 extending from the hexagon 510 where two sides approach each other. The supply aperture 520 has an upper portion 530 and a lower portion 535 that are parallel to each other. According to one embodiment, the upper portion 530 and the lower portion 535 are spaced approximately 5 / 16 inches from the center of the supply aperture 520, creating a 5 / 8 inch opening 525. The upper portion 530 and the lower portion 535 may extend approximately 2 inches from the hexagon 510.

[0034] The manifolds described above may be made from food grade aluminum or stainless steel in one embodiment, in alternative embodiments the manifolds are made from a high temperature plastic such as PVC (polyvinyl chloride) or a combination of PVC and metal.

[0035] FIG. 6 shows a cross-sectional view of two exemplary drying chambers 610, 620 connected by the discharge end 625 of one drying chamber and the opposite end 615 of the other drying chamber, according to one embodiment. The connection between the drying chambers 610, 620 is provided by glue, locks, sealants, covers, or other attachment mechanisms, depending on the embodiment. A continuous belt 630 may be oriented through all of the drying chambers, guided by rollers (not shown). These rollers move the drying belt 630 in a continuous loop from one end of the drying chamber 610 to the other end of the drying chamber 620 and back. The drying belt 630 floats on a heated medium that flows through a groove 640, in one embodiment. According to another embodiment, a single groove is used for the drying chambers, and the water temperature in each groove is controlled independently.

[0036] Channel 640 may include a single pump, or one pump per drying chamber, depending on the embodiment. The pump in channel 640 circulates a heated medium between the heating tank and channel 640. The heated medium may include hot water or other types of heat transfer fluids known to those skilled in the art. The temperature of the hot water or other heat transfer fluid within the heated medium is maintained at a predetermined temperature. Each channel may have its own conditioned air supply manifold 650 and exhaust manifold 660. For example, multiple channels may share a single conditioned air supply manifold 650 and exhaust manifold 660 as shown in FIG. 6. The conditioned air supply manifold 650 and exhaust manifold 660 are connected to the open ends of the drying chambers 610, 620. FIG. 6 shows the conditioned air supply manifold 650 connected to the unused side of the drying chamber 610 and the exhaust manifold 660 connected to the unused side of the drying chamber 620. These additional drying chambers may be added or removed to provide an adjustable dual chamber refraction window dryer according to one embodiment.

[0037] The above exemplary embodiments have been described herein to illustrate various embodiments of implementing the disclosed adjustable conditioning air flow dual chamber dryer. Various modifications and developments from the disclosed exemplary embodiments will occur to those skilled in the art. Subject matter intended to be within the scope of the present disclosure is set forth in the appended claims.

[0038] In the foregoing description, for purposes of explanation, specific terms are used to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required to practice the present invention. Thus, the foregoing descriptions of specific embodiments of the present invention have been provided for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, as many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles and practical application of the invention, thereby enabling others skilled in the art to optimally utilize the invention and various modifications of the embodiments as appropriate for the particular use contemplated. It is intended that the claims submitted later, and their equivalents, define the scope of the present invention.

Claims

1. A drying chamber comprising: a belt having an upper surface configured to transport product along a length of the drying chamber; a heated medium maintained at a predetermined temperature beneath said belt and positioned such that said belt floats above said heated medium, said heated medium comprising a heat transfer fluid; an air supply manifold disposed above and across the width of the belt; and an exhaust manifold disposed over and across the width of the belt; Equipped with air exiting the air supply manifold is configured to flow over the product from the air supply manifold to the exhaust manifold; drying room.

2. 2. The drying chamber of claim 1, wherein the width of the belt is perpendicular to the length of the drying chamber.

3. 2. The drying chamber of claim 1, wherein the air entering the air supply manifold has a predetermined humidity and temperature.

4. 4. The drying chamber of claim 3, further comprising a filtered air system coupled to said air supply manifold that supplies said air at said predetermined humidity and temperature to said air supply manifold.

5. 5. The drying chamber of claim 4, wherein the filtered air system has cooling and heating capabilities.

6. 5. The drying chamber of claim 4, wherein the heated media increases the temperature of the air as it exits the air supply manifold.

7. 2. The drying chamber of claim 1, wherein the air supply manifold is configured to produce an air flow that is uniform across the width of the belt.

8. 2. The drying chamber of claim 1, wherein the air exiting the air supply manifold is configured to flow in a direction counter to the direction of movement of the belt transporting the product.

9. 2. The drying chamber of claim 1, wherein the air supply manifold is located at a product unloading end of the belt and the exhaust manifold is located at a product receiving end of the belt.

10. The drying chamber of claim 1 , further comprising an exhaust fan configured to create a negative pressure environment within the drying chamber.

11. A drying method comprising the steps of: transporting the product on an upper surface of a conveyor belt along the length of the drying chamber, said conveyor belt floating on a heated medium maintained at a predetermined temperature; supplying air to the drying chamber via an air supply manifold positioned above and across the width of the belt; and exhausting the air from the drying chamber through an exhaust manifold positioned above and across the width of the belt so that the air flows over the products during drying. A drying method comprising the steps of:

12. 12. The method of claim 11, wherein the width of the belt is perpendicular to the length of the drying chamber.

13. 12. The method of claim 11, wherein supplying the air to the drying chamber via the air supply manifold comprises supplying the air to the air supply manifold at a predetermined temperature and humidity.

14. 14. The method of claim 13, wherein the heated media increases the temperature of the air as it exits the air supply manifold.

15. 12. The method of claim 11, wherein supplying the air to the drying chamber via the air supply manifold comprises supplying the air to the air supply manifold via a filtered air system.

16. 16. The method of claim 15, wherein the filtered air system has cooling and heating capabilities.

17. 12. The method of claim 11, wherein supplying the air to the drying chamber via the air supply manifold comprises creating an air flow that is uniform across the width of the belt.

18. 12. The method of claim 11, wherein the step of supplying the air to the drying chamber via the air supply manifold includes the step of directing the air to flow in a direction counter to a direction of movement of the belt transporting the product.

19. 12. The method of claim 11, wherein exhausting the air from the drying chamber via the exhaust manifold comprises creating a negative pressure environment within the drying chamber.

20. 12. The method of claim 11, wherein the step of supplying air to the drying chamber via the air supply manifold occurs at a product unloading end of the belt, and the step of exhausting air from the drying chamber via the exhaust manifold occurs at a product receiving end of the belt.

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