Flat heat exchanger plate and bulk material heat exchanger using the same

A flat heat exchanger plate typically used in a bulk material heat exchanger is provided. The flat heat exchanger plate is designed to operate under a negative internal pressure to eliminate depressions or dimples that are typically formed into the sides of these types of heat exchanger coils during the manufacture process. With the removal of the depressions or dimples the tendency for bulk material to accumulate to the exterior surface of the plate is reduced, thereby increasing the service period of the plate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to flat heat exchanger plates for use in heat exchangers. More particularly, relating to flat heat exchanger plates used in bulk material type heat exchangers.

2. Description of the Prior Art

Typically, in processing bulk materials, such as pellets, granules, powders or the like, heat exchangers are employed to either cool or heat the material during the processing thereof. The heat exchangers employed consist of an array of heat exchanger plates arranged side-by-side in spaced relationship and are positioned in an open top and open bottom housing. The like ends of each heat exchanger plate are connected to together by means of a manifold and a heat exchange medium, such as water, oil, glycol or the like is caused to flow through the plates. Generally, the material treated by the heat exchanger is allowed to gravity flow through the housing and the spaces between the spaced plates. During the progression of the material through the heat exchanger, the material is caused to contact the walls of the plates thereby effecting heat transfer between the material and the plates. The rate at which the material flows through the heat exchanger and ultimately across the plates can be controlled by restricting the flow of the material at the outlet of the heat exchanger.

The heat exchanger plates are constructed by attaching metal sheets together along the edges thereof and this is normally accomplished by seam welding the sheets together to form a fluid tight hollow plate. Heretofore, heat exchanger plates have been constructed to operate under internal pressure caused by pumping the heat exchange medium through the plate. To resist internal pressure and to prevent the sides of the plates from deforming, depressions or dimples are formed along the plate. An example of similar heat exchanger plates and their use are described in U.S. Pat. No. 6,328,099 to Hilt et al. and U.S. Pat. No. 6,460,614 to Hamert et al.

During the normal operation of the heat exchanger the bulk material tends to accumulate within the dimples or spot welds and continues to collect to a point where the efficiency of the heat exchanger is greatly reduced and must be cleaned to remove the material residue from the dimples and surrounding exterior surface of the plates. In some circumstances, the material is allowed to collect to a point where the material will bridge between adjacent plates; this not only reduces the heat transfer efficiency of the heat exchanger, but also restricts the flow of the material through the heat exchanger. These circumstances are very undesirable because the operation of heat exchanger must be shut down for a period of time to clean the plates, which many times means the material production line is also shut down, resulting in loss of production and ultimately loss in profits.

Therefore, a need exists for a new and improved flat heat exchanger plate that can be used for bulk material heat exchangers which reduces the tendency for the material to accumulate on the plates. In this regard, the present invention substantially fulfills this need. In this respect, the flat heat exchanger plate according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of increasing the efficiency of bulk material heat exchangers and reducing down time thereof.

SUMMARY OF THE INVENTION

In accordance with the present invention, a flat heat exchanger plate for use in bulk material heat exchangers is provided. The flat heat exchanger plate comprises a plurality of sheets secured together along the edges thereof to form a fluid tight and hollow plate that is generally rectangular in shape. The sides of the plate are substantially smooth and free of depressions, indentations, ridges or the like. The flat heat exchanger plate includes an internal fluid flow passage defined by a plurality of flow diverters, which are positioned within the hollow space of the plate. Heat exchange medium is directed into an inlet nozzle formed in the plate and out of a similarly designed exit nozzle formed in the plate. Unlike a conventional heat exchanger plate, the plate of the present invention is designed to operate under a negative internal pressure opposed to a positive internal pressure. Because the plate is designed to operate under a negative internal pressure the dimples or otherwise depressions formed on the exterior surfaces of prior art plates to withstand internal positive pressure loading are eliminated. In doing so accumulation of material on the exterior surface of the plate is reduced to a very minimal amount.

To withstand the negative pressure within the flat heat exchanger plate, pressure-resisting elements are positioned within the plate and may be unattached or secured to either or both internal surfaces of the sidewalls of the plate. The pressure resisting members or pressure resistor members prevent the sidewalls of the plate from deforming or collapsing inward due to the negative operating pressure present within the plate.

During initial filling of the flat heat exchanger plate with a heat exchange medium or during non-operational periods of the plates, the sides of the plate may tend to bow outward causing the plate to inflate due to the low positive pressure exerted by the heat exchange medium present within the plate in a static state. To prevent this from occurring, pressure restraint members are positioned within the plate and are secured to both sides of the plate, thereby preventing the interior distance between the sides of the plates from increasing.

Flow diverters are positioned within the flow passage of the flat heat exchanger plate and create flow channels for the heat exchange medium to follow. The flow diverters can be formed to any suitable shape from flat stock material or from solid or hollow sectional material and in some applications plastic mouldings could be employed. In addition, the flow diverters can also aid the pressure resistors in preventing the flat heat exchanger plate from collapsing due to internal negative pressures.

An additional advantage of operating the flat heat exchanger plate under negative pressure is the ability to use manifolds that are less expensive and less heavy duty than that of the manifolds required for heat exchanger plates that operate under positive pressure. A lighter duty and less costly manifold, typically a section of pipe or any hollow section material can be used.

In additional embodiments of the flat heat exchanger plate of the present invention, the plate is constructed with tapered sides, which is beneficial in the flow of fine particulate material. The increasing width of the material flow path due to the tapered design of the plate will reduce pressure build-up in the material, thereby making it less likely for particles to accumulate on the sides of the plate.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and particularly toFIGS. 1–2, a preferred embodiment of the flat heat exchanger plate of the present invention is shown and generally designated by the reference numeral10.

InFIGS. 1 and 2a new and improved flat heat exchanger plate10of the present invention for the purpose of increasing the efficiency of bulk material heat exchangers and reducing down time thereof is illustrated and will be described. More particularly, inFIG. 1, the flat heat exchanger plate10has a flat, generally rectangular metal body12having two opposing side sheets14, two opposing longitudinal edges16, and two opposing transverse edges18. The two side sheets14are sealed to each other along the borders of the two longitudinal and two transverse edges16and18defining an open interior space.FIGS. 3a–3dillustrate possible methods of seaming the edges of the flat heat exchanger plate10. Heat exchange medium inlet and exit nozzles20and22are provided in fluid communication with the open interior space and can be arranged for example along a common longitudinal edge16.

Each side sheet14is substantially smooth and free of depressions and/or dimples or the like. The phrase “substantially smooth” is to be defined in the context of this application for U.S. Letters Patent as free from ridges, depressions, and dimples or the like created in the sides of the flat heat exchanger plate during the manufacture thereof.

Prior art heat exchanger plates are manufactured with dimples and/or depressions formed on the sides thereof and welded together to increase the resistance of the sides from bowing outward due to a positive internal operating pressure created by pumping a heat exchange medium through the plate. These dimples are a drawback to prior art plates because in service bulk material tends to accumulate in these dimples which has a negative two fold effect. First, the heat transfer between the bulk material and the plate is reduced by a loss of effective surface area of the plate and second the bulk material may be allowed to accumulate to a point where the material bridges between adjacent plates thereby impeding the flow of the material through the heat exchanger. Once this occurs, the heat exchanger must be removed from service and cleaned, which results in undesirable down time of the material production line. To over come the drawbacks of the prior art, the flat heat exchanger plate10of the present invention is designed to operate under a negative internal pressure, thereby eliminating the need to create dimples on the sides of the plate.

Turning toFIG. 2, numerous flat heat exchanger plates10are illustrated in an exemplary in-use arrangement positioned within a typical bulk material heat exchanger24. The flat heat exchanger plates10are arranged side-by-side in a spaced relationship within the shell of the bulk material heat exchanger24. The inlet nozzle20of each plate10is connected to a common heat exchange medium supply manifold26and the exit nozzle22of each plate is also connected to a common heat exchange medium return manifold28. The inlet nozzle20and the exit nozzle21can be formed to any suitable shape, such as but not limited to a rectangle or a circle. In operation, a vacuum source is provided at the heat exchange return manifold28and the flow of the heat exchange medium is indicated by arrows30, where the heat exchange medium enters the supply manifold26and is distributed to each of the inlet nozzle26of each plate10. The heat exchange medium is then drawn up and through each plate10and ultimately out of the heat exchange medium return manifold28. Arrows32indicate the flow of the bulk material, and the material flows through the heat exchanger and across the plates10, typically under the force of gravity. With this arrangement, the bulk material heat exchanger24operates as a counter flow type heat exchanger.

The flat heat exchanger plate10as indicated above, is designed to operate under a negative internal pressure or vacuum as low as about 10 psi (70 kPa) on a vacuum gage. To prevent the side sheets14of the flat heat exchanger plate10from collapsing at least one pressure resistor member34is positioned and strategically arranged within the interior space of the plate. During non-operational periods of the plate10, a positive internal pressure may be present due to the hydrostatic pressure of the heat exchange medium present within the plate in a static state. To prevent inflation or deforming of the sides of the plate10, at least one pressure restraint member36can be included and is positioned and strategically arranged within the interior space of the plate.

At least one flow diverter38is positioned within the flat heat exchanger plate10to a create flow passage for the circulating heat exchange medium to flow through. Preferably, flow diverters38are arranged to create a serpentine-like flow path for the heat exchange medium. The flow diverters38can also aid the pressure resistor members34in preventing the sides of the plate10from collapsing.

FIG. 4illustrates a pressure resistor member34positioned between the interior surfaces40of the side sheets14of the flat heat exchanger plate10. The pressure resistor member34is generally cylindrical and is attached at one end to one interior surface40of a single side sheet14. Preferably, the pressure resistor member34is attached at one end to the interior surface40by a weld42with the opposite end of the pressure resistor member free from attachment to the opposing interior surface of the other side sheet. In a preferred embodiment, the pressure resistor member34is of a length equal to the distance between the interior surfaces40of the plate side sheets14. In the manufacture of the plate10, a predetermined number and arrangement of pressure resistors34are first attached in a desired pattern to the interior surface40of the side sheets14before the side sheets are assembled with the plate10.

Turning toFIG. 5a, one possible embodiment of a pressure restraint member36is illustrated and will be described. The pressure restraint member36is attached at one end to one interior surface40of one side sheet14by weld44. The opposite end of the pressure restraint member is plug welded46to the opposite side sheet14through a hole48formed therethrough and dressed flush with the exterior surface54of the side sheet. In this embodiment, the pressure restraint member36is cylindrical in shape and is of a length equal to the distance between the interior surfaces40of the side sheets14.

Now turning toFIG. 5b, an alternate embodiment of a pressure restraint member36is illustrated and will be described. The pressure restraint member36is attached at one end to one interior surface40of a side sheet14by a weld44. In this embodiment, the pressure restraint member36is of a length to pass through a hole50formed through the opposite side sheet14and is welded52around the hole50. In this application, the weld52and the end of the pressure restraint member are dressed flush with the exterior surface54of the side sheet14.

Referring toFIGS. 5c–5e, an alternate embodiment of a pressure resistor member34and a pressure restraint member36is illustrated and will be described. The pressure resistor member34and the pressure restraint member36have a cylindrical body, closed at one end56and a flanged end58. Application of the pressure resistor member34is illustrated inFIG. 5d, where the flanged end58is attached to the interior surface40of one side sheet14by a circular weld60. The pressure resistors34can be attached to the interior surfaces40of the side sheets14in an alternating pattern as illustrated. Application of the pressure restraint member36is illustrated in5e, where the flanged end58is attached to the interior surface40of one side sheet14by a circular weld60. Then on assembly with the other side sheet14, the cylindrical body56is weld thereto by weld62. The pressure restraint member s36can be attached to the interior surfaces40of the side sheets in an alternating pattern as illustrated.

Turning now toFIG. 6a, which is a cross sectional view of the flat heat exchanger plate10as illustrated inFIG. 1. This figure shows an example of one possible form of a flow diverter38positioned within the plate10and between the side sheets14. In this example, the flow diverter38is a strip of material having a bend of approximately 90 degrees along a centerline thereof. The flow diverter38includes a plurality of holes64formed therethrough along the centerline thereof. The holes64allow the flow diverter38to be positioned about an arrangement of pressure resistors34and/or pressure restraint members36. Referring back toFIG. 1, which illustrates the placement of multiple flow diverters38about the pressure resistors34and pressure restraint member s36to create a serpentine flow path for the heat exchange medium. The positioning of the flow diverters38as illustrated is for exemplary purposes only as the flow diverters can be arranged in any manner to create a desired flow path for the heat exchange medium.

FIG. 6billustrates an example of a combined flow diverter and pressure resistor38positioned within the flat heat exchanger plate10between the side sheets14. In this example, the combined flow diverter and pressure restraint38is a strip of material having opposed edges bent orthogonal to the side sheets14to form two legs15. These legs act as pressure resistors to prevent the collapse of the plate10when operated under a negative pressure. The diagonal web17includes a plurality of locating holes64, and creates to flow passages19for the heat exchange medium.

FIG. 6cillustrates an additional example of a combined flow diverter and pressure resistor38in the form of a corrugated formed sheet of material positioned within the flat heat exchanger plate10and secured to the interior surfaces40of the side sheets14.

Turning toFIGS. 7,8aand8ban alternate embodiment of the flat heat exchanger plate10and flow diverters38of the present invention is illustrated and now will be described. In this embodiment, the flow diverters38are formed from a solid rod or tube, which are bent and positioned within the plate10to create a desired heat exchange medium flow path. The pressure resistors34and the pressure restraint member s36are strategically positioned and attached to the side sheets14of the plate10to aid in the correct placement of the formed flow diverters38. Preferably, the pressure resistors34and restraints36are positioned to alternate from side to side of the flow diverters38, as illustrated inFIG. 7.FIG. 8ais an enlarged partial cross section of the plate10illustrated inFIG. 7and this figure shows a flow diverter formed from a solid rod and illustrates the method of positioning the pressure resistors34and/or restraints36on opposite sides of the flow diverter38to aid in the positioning and retention thereof.FIG. 8billustrates an alternate embodiment of the flow diverter38illustrated inFIG. 8a. In this embodiment, the flow diverter is a tube. The flow diverters38illustrated inFIGS. 7,8aand8bare of a material having a circular cross section for exemplary purposes only and should not limit the possibility of using material of other cross sectional shapes.

Referring now toFIGS. 9,10aand10b, which illustrate an additional embodiment of the flat heat exchanger plate10of the present invention. In this embodiment the thickness of the plate10decreases in the direction from one transverse edge to the second transverse edge. Preferably, the thickness of the plate10decreases in the direction of the flow of bulk material across the coil. Preferably in this particular embodiment incremental steps66decrease the thickness of the plate10. Most preferably, the steps66and thickness of the plate10correspond with the various diameters of rod or tube used for the flow diverters38.FIG. 9also illustrates an additional possible arrangement of the flow diverters38to create a serpentine flow path for the heat exchange medium. As in all of the aforementioned embodiments of the flat heat exchanger plate10, the flow diverters in this embodiment can aid the pressure resistors34in preventing the side sheets14of the plate10from collapsing. During the manufacture of this embodiment of the flat heat exchanger plate10the longitudinal edges16are cut to match the step profile of the side sheets14of the plate. Preferably, the longitudinal edges16are laser cut to match the step profile of the side sheets14.

FIG. 10ais a side elevation view illustrating an example of one method of creating a tapered flat heat exchanger plate10. In this example, the side sheets14of the plate10are formed by overlapping sections of sheet metal68, as illustrated, which are then welded together. The thickness of the flow diverters38are equal to the distance between the interior surfaces40of the side sheets14for each step66of the plate10. For exemplary purposes only, the flow diverters in this figure are illustrated as solid rods.

FIG. 10billustrates a side elevation view illustrating an example of a second method of creating a tapered flat heat exchanger plate10. In this example, a single sheet is used for each side sheet14and the sheet is bent inward at various positions along the length thereof to create the required stepped profile of the side sheet. The thickness of the flow diverters38are equal to the distance between the interior surfaces40of the side sheets14for each step66of the plate10. For exemplary purposes only, the flow diverters in this figure are illustrated as tubes.

Referring now toFIGS. 11,12and13, which illustrate a third embodiment of the flat heat exchanger plate10of the present invention and an additional example of a flow diverter assembly38for use with a tapered or parallel plate. The flow diverter assembly38of this embodiment includes a plurality of tapered flow diverter strips70which are interlocked with a plurality of flow control strips72. Preferably, the flow control strips72and the tapered flow diverter strips70are interlocked orthogonal to each other. The flow control strips72include a plurality of reduced sections74, which are formed to be positioned between adjacent tapered flow diverter strips70and serve to control the amount of heat exchange medium that passes each flow control strip. The flow diverter38of this embodiment is also used to prevent the tapered plate10from collapsing under negative operating pressure. Pressure restraint members36(not illustrated) may also be used in the same manner as described previously to prevent inflation of the plate10and to help position the flow diverter38within the plate.

Referring toFIGS. 13band13c, which illustrate a fourth embodiment of the flat heat exchanger plate10of the present invention and an additional example of a plurality of flow diverters38for use with tapered or parallel flat heat exchanger plate. The flow diverter38of this example is a tapered or parallel strip of material formed in a serpentine shape and includes a heat exchange medium flow control leg39. The flow control leg39restricts the flow of heat exchange medium into each chamber41to ensure an even flow rate of heat exchange medium within each chamber across the plate. The flow diverter38of this example is also used to prevent the plate10from collapsing under negative operating pressure. In addition to the flow diverters38, pressure restraint members36. not illustrated, can be used in the same manner as previously described to prevent inflation of the plate10and to aid in the positioning of the flow diverters38within the plate.

Turning toFIGS. 14 and 15a fifth method of creating a tapered flat heat exchanger plate10is illustrated. The flat side sheets14are in parallel planes and increase in width in a direction from one transverse edge18of the plate10to second transverse edge18of the plate. Preferably, the thickness of the plate10remains constant along the length of the plate. The gradual increase in width of the plate10creates a greater volume between adjacent plates in a bulk material heat exchanger, which releases pressure build-up in particulate material flowing through the heat exchanger. The flow diverters38of this example are of an open channel material having a closed side76and an open side78that includes a pair of flanges80. The flat heat exchanger plate10is constructed by first attaching a plurality of flow diverters38to the interior surface40of one side sheet14by welds82. The plurality of flow diverters38are attached to the side sheet14in a desired pattern to create a flow path for the heat exchange medium. Then the second side sheet14is attached to the plate10and the flow diverters38by welds84from the exterior side of the second sidewall. Preferably, the welds are laser welded. This method of construction provides for the placement of the flow diverters38within the plate and allows the flow diverters to function as pressure resistors and restraints.

Now turning toFIG. 16, a removable seal86may be positioned between adjacent flat heat exchanger plates10to retain the flow of material88therebetween. The seal may be removed to help facilitate the cleaning of the plates10or by adjusting the vertical angle of the seal to control the flow of material88between the plates.

Referring toFIGS. 17 and 18, which illustrate a typical placement of support holes90through the flat heat exchanger plate10. The support holes90, which may be of any desired shape, are formed through both side sheets14. A tubular sleeve91is placed in the support holes90then welded to both side sheets14and then dressed flushed with the exterior surfaces of the side sheets. The support holes90are typically used in supporting the flat heat exchanger plate10within a heat exchanger.

Now turning toFIG. 19, which illustrates the capability of incorporating the placement of location lugs92, which extend from the ends of the flat heat exchanger plate10, indents94formed into the ends of the plate, support lugs96extending from the edges of the body of the plate and a lifting lug98extending from the top of the plate. Currently, plate heat exchangers are manufactured with supports below the plates which can impede the flow of bulk material and also increase the overall height of the heat. The incorporation of location lugs92, indents94, support lugs96, or a lifting lugs98eliminates the need for the supports below the plates10and improves the flow path for the bulk material. The overall height of the heat exchanger can be reduced correspondingly.

Referring toFIGS. 20aand20b, an additional embodiment the flat heat exchanger plate10is illustrated and will be described. In this embodiment, the flat heat exchanger plate10is designed and manufactured such that upon removal of the negative operating pressure the flat heat exchanger plate sides14will slightly inflate due to a positive internal pressure created exerted by the heat exchange medium. Isolating the vacuum source and allowing the heat exchange medium to develop a desired hydrostatic pressure within the flat heat exchanger plates10can achieve the slight inflating of the plate coil sides14. Upon reestablishing the negative operating pressure, the flat heat exchanger plate sides14return to a non-inflated position. Preferably, the hydrostatic pressure is allowed to reach a about 5 PSI (34 kPa) and is only applied for a short duration. The duration is at least 1 second. Preferably the duration is from about 1 to about 10 seconds and most preferably, the duration is about 5 seconds. An automated pulsing system100can be incorporated in the heat exchange medium system102to cause the inflation-deflation cycle of the flat heat exchanger plates10at a predetermined frequency.

Incorporating the above cyclic inflation of the flat heat exchanger plates10in, for example a bulk material heat exchanger would be beneficial in processing fine particulate materials which tend to bridge across narrow spaces such as the gaps between adjacent flat heat exchanger plates, which creates blockages in the flow of the material. By inflating the flat heat exchanger plate sides14by a small fraction of an inch the gap between adjacent flat heat exchanger plate decreases thus compressing any bulk material in the gap. On returning the flat heat exchanger plate sides14to the non-inflated position, the gap between adjacent flat heat exchanger plate increases to the normal operation gap and the compressed bulk material is dislodged from the sides. This system provides for the automated, self-cleaning of flat heat exchanger plates10, which reduces operating costs and service time of the flat heat exchanger plates.

In an additional embodiment of the flat heat exchanger plate system of providing automated, self-cleaning flat heat exchanger plate10is illustrated inFIGS. 21a,21band21c. In this embodiment, the self-cleaning system includes a lift means106for lifting the flat heat exchanger plate10to aid in the removal of any bulk material that has accumulated on the exterior surfaces of the flat heat exchanger plate. In one example, the flat heat exchanger plate10are supported on a bar104passing through sleeves91, which can be extended as illustrated to maintain the flat heat exchanger plate spacing. Referring back toFIG. 2, a flexible connection is incorporated between the flat heat exchanger plate inlet nozzles20and the inlet manifold26, and a similar flexible connection is incorporated between the flat heat exchanger plate exit nozzles22and the outlet manifold28. InFIGS. 21aand21b, the ends of the bar104are supported by the casing of the bulk material heat exchanger24. The lift means106for lifting and rapidly dropping the bar104and the flat heat exchanger plates10is attached to the bar. The lift means106would raise the bar104off of its supports105by a fraction of an inch, as illustrated inFIG. 21aand then allowed to fall under the effect of gravity back onto the supports as illustrated inFIG. 21b. By the lift means106, the flat heat exchanger plates10supported by the bar104are raised and dropped resulting in developing a shock wave through the flat heat exchanger plate. The resultant shock wave will dislodge any present bulk material blockage between adjacent flat heat exchanger plates10.

The lift means106could incorporate, for example a cam108that is driven by motor110. The cam108is in contact with the cam follower112attached to the end114of the bar104. The cam108can include a gradual lift profile about a predetermined number of degrees of rotation and a flat profile about a predetermined number of degrees of rotating.FIG. 21cillustrates an example of a cam profile that could be used. The lift profile of the cam108will gently raise the support bar104and the flat heat exchanger plates10to a maximum predetermined lift that is a fraction of an inch. The flat profile109of the cam108will cause the bar104to free fall under the force of gravity the distance it was originally raised causing the bar to impact its support105, thereby forming a shock wave through the flat heat exchanger plates10.

Referring toFIGS. 22a,22band22c, an additional example of the lift means106is illustrated and will be described. A cam116for each flat heat exchanger plate10can be incorporated into the support bar104and a cam follower118can be incorporated into each sleeve91. Upon rotation of the support bar104, for example by attaching an end114of the support bar to the shaft of a motor, the flat heat exchanger plates10are raised and lowered based upon the profile of each cam116. Preferably, the maximum lift of each cam116is sequentially offset so that each flat heat exchanger plate10will be raised and lowered in predetermined sequence thus creating a shearing effect in the material between each adjacent flat heat exchanger plate. Turning toFIG. 22b, the cam profile of the cam116can include a steep profile section120which would cause the flat heat exchanger plate10to fall under the force of gravity a predetermined distance in accordance with the profile section120. This fall would send a shock wave through the flat heat exchanger plate10and aid in the removal of the material from of the exterior surface thereof.

FIG. 22cillustrates an additional example of a cam profile for the cam116that could be used. In this example, the flat heat exchanger plates10would be raised and lowered in a predetermined sequence thus creating a shearing effect the material between each adjacent flat heat exchanger plate. The incorporation of a scraper element122into the bearing surface of the sleeve91would act to keep the surface of the cam116clear of material debris that could impede the operation of the cam.

Referring toFIG. 23, which illustrates an example of a cam arrangement including an eccentric cam116and cam followers118incorporated into the sleeve91of a plate coil. In this example, upon rotation of the support bar104the cam followers118would follow the profile of the cam116and flat heat exchanger plate10would translate horizontally back and forth. Such as described above a plurality of cams116would be incorporated along the length the support bar104with the maximum lift of each cam116offset from each other to create a shearing effect in material between each adjacent flat heat exchanger plate.

Referring toFIG. 24, which illustrates an additional cam arrangement example including a plurality of lateral cams116cut into the support bar104and a cam follower118incorporated into the sleeve91of each flat heat exchanger plate10. In this example, upon rotation of the support bar104the cam follower118would follow the profile of the lateral cam116cut into the support bar104and the flat heat exchanger plates10would translate horizontally from side-to-side in unison. In addition, the sleeves are extended to provide spacing for adjacent flat heat exchanger plates10. The side-to-side, unison movement of the plate coils10aids in dislodging bulk material accumulated between adjacent flat heat exchanger plates.

A method of automated cleaning of the exterior surfaces of adjacent flat heat exchanger plate10is provided and includes the steps of providing at least two flat heat exchanger plates10arranged side-by-side in a spaced relationship, wherein the flat heat exchanger plates include a heat exchange medium inlet nozzle and an exit nozzle20and22. Attaching the heat exchange medium inlet20and exit nozzles22to a heat exchange medium supply system102, wherein the supply system includes a vacuum source which is attached to the heat exchange medium exit nozzles for creating a negative operating pressure within the flat heat exchanger plates. Isolating the vacuum source allowing the heat exchange medium to develop a predetermined desired hydrostatic pressure within the flat heat exchanger plates10to slightly inflate the flat heat exchanger plates to reduce the space between the flat heat exchanger plates and compress any bulk material that is accumulated on the exterior surfaces of the sides of the flat heat exchanger plates. And reconnecting the vacuum source to reestablish the negative operating pressure and thus deflating the flat heat exchanger plates10to increase the space between the plates and dislodge the compressed bulk material.

This method may also include connecting a pulsing100system between the vacuum source and the exit nozzles of the flat heat exchanger plates10to isolate the vacuum source and reconnect the vacuum source in a cyclic manner having a predetermined frequency.