Patent ID: 12188721

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

Referring to the accompanying figures there is illustrated a vacuum drying apparatus generally indicated by reference numeral10. The apparatus10is particularly suited for drying a stored particulate material, for example grain stored in a grain bin, without any addition of heat from a heater being required.

The apparatus10generally comprises (i) a bin structure12defining a rigid frame and boundary walls for structurally supporting stored materials within an internal storage volume of the structure, (ii) one or more material gate assemblies14communicating through the bin structure to the interior storage volume for loading particulate material into the bin structure or unloading particulate material from the bin structure, (iii) an air inlet passage16communicating through the bin structure to allow external air to enter into the interior storage volume, (iv) an exhaust passage18communicating through the bin structure to allow air to be exhausted externally from the interior storage volume, and (v) a vacuum device20for generating a vacuum pressure to be applied to the interior storage volume of the bin structure.

The air inlet passage16is flow restricted relative to the exhaust passage, for example by use of a flow restrictor valve22connected in series with the air inlet passage.

In the illustrated embodiment, a liner24is provided within the interior storage volume so at least partially define an airtight envelope that lines the inner surfaces of a majority of the interior storage volume of the bin structure. More particularly, the liner24is joined to a rigid hopper bottom26of the bin structure12such that the liner24and the hopper bottom26collectively define the airtight envelope, in which the hopper bottom26forms the lower boundary of the envelope while the line24forms upright side boundaries and a top boundary of the envelope.

The envelope fully occupies the interior storage volume and receives the stored material in the bin structure within the interior of the envelope. The air inlet passage16, the exhaust passage18, and the one or more material gate assemblies14all communicate through the airtight envelope in sealed relation therewith in addition to communicating through the bin structure.

The use of a vacuum device, a flow restricted air inlet passage, and an airtight membrane, create an environment of negative pressure with a modest airflow within the interior of the envelope. The negative pressure causes the moisture in the grain to more readily turn into vapour to be carried away in the airflow to the exterior of the bin structure.

Turning now more particularly to the configuration of the bin structure12, as shown in the accompanying figures, the bin structure is generally rectangular in shape when viewed from above. A bottom boundary of the interior storage volume of the bin structure is defined by the hopper bottom26comprised of four floor panels each sloping downwardly and radially inwardly towards a central material discharge passage28associated with an outlet gate assembly among the gate assemblies14.

The floor panels of the hopper bottom26are all joined to one another and form a rectangular perimeter edge at the top end thereof connected to four side panels30extending upwardly from the perimeter of the hopper bottom at the four sides of the bin structure respectively. The slope of the floor panels is sufficiently steep that no grain tends to collect on the inner surface thereof to ensure full cleanout.

The floor panels of the hopper bottom26are sealed relative to one another to form a continuous, airtight, lower boundary of the envelope when the top edges of the floor panels are joined to the bottom edge of the liner24by a continuous sealing member27extending about the perimeter of the storage bin.

The side panels30define lateral boundaries of the interior storage volume extending vertically upward from the perimeter of the hopper bottom26.

A top end of the bin structure is enclosed by a roof comprised of four roof panels32which are sloped upwardly and radially inwardly towards a central material inlet passage34. Each roof panel is joined to the top edge of a respective one of the side panels30and is joined to adjacent roof panels to form a complete enclosure about the interior storage volume. The roof panels form an upper boundary of the interior storage volume. The roof panels also have considerable slope so as to exceed the angle of repose of particulate material loaded into the bin to ensure that entering grain fills to the top of the side walls prior to contacting the inner surface of the roof panels.

The floor panels of the hopper bottom26, the side panels30and the roof panels32of the bin structure are formed of sheeted material having smooth inner surfaces forming the boundary walls about the interior storage volume. All of the panels are supported externally by a bin frame36comprised of a suitable arrangement of posts, floor beams and roof beams joined at the exterior side of the panels to provide efficient structural support to the panels. The frame further comprises a set of legs38which support the hopper bottom26at a location spaced above a base40of the bin frame to provide sufficient clearance below the material discharge passage28to allow grain handling equipment to be received below the discharge passage under the hopper bottom of the bin structure.

The bin structure further comprises a discharge collar42joined to the floor panels of the hopper bottom to surround and define the central discharge passage28extending downwardly therethrough externally of the bin. The bin structure similarly comprises an inlet collar44joined to the roof panels32to surround and define the central material inlet passage34extending downwardly therethrough into the bin.

The liner24of the apparatus10is a flexible membrane formed of plastic sheet material. The liner is formed of panels of the sheet material which span the inner surface of corresponding panels of the bin structure. The panels of the membrane are joined to one another to form an airtight seam at the junction of each adjacent pair of liner panel. The liner material further comprises a collar portion lining the inlet collar44in which the collar portion is also joined with an airtight seam with the remaining panels of the liner. The liner material has a minimal thickness compared to the thickness of the rigid panels forming the bin structure such that the resulting envelope formed by the liner material occupies the interior storage volume of the bin structure and includes an interior volume that substantially corresponds to the interior storage volume of the rigid bin structure.

The liner24is joined at the bottom end of the liner to the rigid bin structure at the junction of the floor panels of the bin structure to the side panels of the bin structure. The liner is further supported relative to the bin structure at the junction of the roof panels to the inlet collar44at the top end.

An upper portion of the liner envelope including the roof panels and some or all of the side panels can be suspended relative to the rigid bin structure so as to be movable inwardly away from the boundary walls of the bin structure to enable the upper portion of the liner to be collapsed inwardly into the interior of the bin structure. In this manner an interior volume within the envelope can be reduced about the stored product contained therein under vacuum pressure. In particular, when the particulate material is filled into the bin structure so that an upper boundary of the stored product is in proximity to the top end of the bin structure, the upper portion of the liner may be collapsed inwardly directly against the upper boundary of the stored product as represented schematically inFIG.1.

In some embodiments, the liner at the upper portion may be sufficiently collapsed against the upper boundary of the product stored in the bin that the collapsed liner fully encloses the upper boundary of the product so that no sealing is required of the liner at the material inlet passage34as the material inlet passage34is instead effectively sealed closed by the upper portion of the liner collapsing upon itself across the passage.

A lifting mechanism is provided for lifting the upper portion of the liner back into close contact with the inner surface of the upper boundary walls of the bin structure when no vacuum pressure is applied to the envelope such that the liner does not interfere with loading of particulate material into the bin structure as shown inFIG.2. In this instance, a set of flexible cables46may be coupled between the liner and the boundary walls at the junction of the side panels to the roof panels and at the junction of the roof panels to the inlet collar44.

In one example, a set of winches48may be supported externally of the bin structure in operative connection to the flexible cables to enable the cables to be wound up onto the winches for drawing the liner upwardly against the inner surfaces of the upper boundary walls of the bin structure. Releasing the winches when vacuum is applied to the interior volume of the envelope would allow the upper portion of the envelope to again be collapsed inwardly against the upper boundary of the stored product.

In yet further arrangements, the winches may be spring biased or the flexible cables themselves may be elastic members which tend to automatically return the liner upwardly into engagement with the upper boundaries of the bin structure in the absence of vacuum pressure, while being further arranged such that application of vacuum pressure is sufficient to draw the liner inwardly against the upper boundary of the stored product against the biasing of the springs.

As noted above, the gate assemblies14include an inlet gate assembly operatively connected to the inlet collar44at the top end of the bin structure. In this instance, an inlet material passage34is defined through the inlet collar44which can be selectively closed by a suitable gate member in the form of a lid50. The lid may be hinged to pivot between open and closed positions.

A liner panel52may span the inner side of the gate member50such that the gate member and the liner panel52on the interior side thereof may fully span across the inlet passage34in sealed relation with the liner material forming the envelope in the closed position of the inlet gate assembly. In the open position, the gate member50is pivoted upwardly and radially outwardly relative to the inlet collar44such that the inlet passage34is substantially unobstructed by the gate member50to enable loading of particulate material downwardly through the inlet collar44into the interior of the envelope.

The gate assemblies14further include a discharge gate assembly operatively connected to the discharge collar42at the bottom end of the bin structure. The discharge gate assembly also includes a gate member54, for example in the form of a slide gate supported for horizontal sliding relative to guide channels formed in the discharge collar42. The gate member54comprises a rigid panel having a liner panel56spanning the top or interior side of the rigid panel. In this manner the gate panel54can be slid horizontally between open and closed positions relative to the discharge passage28.

In the closed position, the liner panel56fully spans across the discharge passage28in sealed relation with the surrounding hopper bottom26so as to be in sealed relating with the envelope defined by the hopper bottom26and liner24also. In the open position, the gate member54is displaced laterally and radially outward relative to the discharge collar42to enable unloading of particulate material downwardly through the discharge collar to the exterior of the envelope and the exterior of the bin structure.

The air inlet passage16is situated to communicate through the side panels of the bin structure and the liner portion of the envelope at a location adjacent to the top end of the side panels so as to be closer to the top end than the bottom end of the bin structure. The air inlet passage is defined within the interior of an inlet duct58extending through the side of the bin structure and the liner in sealed relation with the liner by an annular flange gasket60surrounding the inlet duct to seal the inlet duct relative to the liner. The inlet duct58is connected at an inner end within the interior of the envelope to an upper manifold duct62. The full duct62is ring shaped having an overall lateral dimension which is slightly less than corresponding lateral dimensions within the interior of the storage bin at the side panels of the bin structure so that the manifold duct remains spaced inwardly from the perimeter of the bin about the full circumference thereof.

The manifold duct is a round duct allowing flow therethrough about the full circumference of the duct. The duct is formed of a perforated material having perforated openings which are sized to allow air into the interior of the storage bin from the inlet duct58while preventing particulate material stored within the bin from entering into the manifold duct. When vacuum is applied to the interior of the envelope, air is drawn from the exterior of the bin through the inlet duct and into the upper manifold duct62such that the air flows circumferentially in two opposing directions from the communication of the manifold duct with the inlet duct58towards the diametrically opposing side of the manifold duct while being vented externally of the duct and into the surrounding bin structure as the air flows circumferentially about the manifold duct.

The exhaust passage18is situated to communicate through the hopper bottom26of the bin structure and envelope so as to similarly communicate through the envelope in sealed communication with the envelope. The exhaust passage18is located adjacent to a bottom end of the bin structure so as to be closer to the bottom end than the top end of the bin structure. The exhaust passage is defined within the interior of an exhaust duct64extending through the lower boundary of the envelope in sealed relation with the envelope by an annular flange gasket60surrounding the exhaust duct to seal the exhaust duct relative to the envelope. The exhaust duct64is connected at an inner end within the interior of the envelope to a lower manifold duct66. The lower manifold duct66is substantially identical to the upper manifold duct62other than being positioned spaced therebelow towards the bottom end of the bin structure in close proximity to the hopper bottom thereof.

The lower manifold duct66is also a round duct formed of perforated material having perforated openings which are sized to allow air into the lower manifold duct from the interior of the storage bin while preventing particulate material stored within the bin from entering into the manifold duct. When vacuum is applied to the exhaust duct, air is drawn from the interior of the envelope into the lower manifold duct66through the perforations about the full circumference of the lower manifold duct. This results in a circumferential flow of air from two opposing portions of the lower manifold duct towards one another at the junction of the lower manifold duct with the exhaust duct64, followed by continued flow through the exhaust duct to the exterior of the bin structure.

A set of support legs68are mounted in fixed relation to the interior of the hopper bottom of the bin structure within the lower boundary of the envelope so that the support legs can extend upwardly into the interior of the envelope and connect to both the lower manifold duct66and the upper manifold duct62thereabove to provide structural support that fixes the manifold ducts relative to the bin structure.

Turning now to the flow restrictor valve22mounted in series with the air inlet passage16, the valve in this instance comprises a valve seat70fixed within the inlet duct58and a valve member72which is axially movable in the longitudinal direction of the duct relative to the valve seat between open and closed positions of the valve. The valve seat is generally conical in shape, tapering in the axial direction of the duct towards a central opening in the valve seat. The valve member72is similarly conical in shape to fit tightly against the valve seat70in the closed position and thereby fully close the central opening in the valve seat to prevent air flow through the valve. By displacing the valve member72axially relative to the valve seat, the cross-sectional area between the valve member72and the valve seat70can be adjusted to vary the cross-sectional flow area through the valve and in turn provide a varied restriction to the flow.

The valve member72is supported on the inner end of a shaft74extending axially through the inlet duct while being supported relative to the duct by a pair of hubs76. Each hub includes an outer ring78having an outer diameter that fits securely within the inner surface of the surrounding duct, a central ring80defining a central opening therein that receives the shaft74therethrough, and a plurality of spokes82extending radially between the outer ring58and the central ring80. An innermost one of the hubs76includes a threaded bore within the central ring80which forms a threaded engagement with a threaded portion of the shaft74. The other hub76includes a bushing supported within the central opening in the central ring to merely provide longitudinal sliding support to the shaft74relative to the surrounding duct.

A suitable handle84is mounted on the outer end of the shaft74at the exterior of the inlet duct opposite the valve member at the inner end of the shaft. When an operator manually rotates the handle about a longitudinal axis of the shaft, the resulting rotation of the shaft74and the threaded engagement of the shaft with one of the hubs76causes the valve member72to be axially displaced relative to the valve seat to open and close the valve and to adjust the valve between any one of a plurality of different flow areas between the open and closed positions.

In further embodiments, the flow restrictor valve may be operated by a suitable electric actuator to control the amount of restriction provided by the valve.

The apparatus further includes a control valve86connected in series with the exhaust duct64between the corresponding manifold duct within the interior of the bin structure and the vacuum device20coupled to the exterior end of the exhaust passage. The control valve86can be similarly operated between open and closed positions or positioned at a variety of intermediate positions corresponding to different amounts of flow restriction to the exhaust passage between the opening closed positions of the valve. In a normal operating position of the control valve, the exhaust passage is substantially unrestricted or much less restricted than the air inlet passage. The control valve86may be a butterfly valve as shown in further detail inFIG.10.

In further embodiments, the control valve may be operated by electric actuators that it can be controlled by a suitable controller associated with the apparatus10.

The vacuum device20may be any one of a variety of fans or pumps which are suitable for generating a sufficient vacuum pressure within the interior of the envelope of the bin structure. In the illustrated embodiment, the vacuum device is a centrifugal fan including a housing88supporting stationary vanes90therein and a rotor92having rotor vanes94supported thereon which are rotatable together relative to the stationary vanes in the housing88.

The rotor92is supported for rotation relative to the housing about a respective rotor axis. The rotor92is generally cylindrical in shape having a first side wall96which is circular in shape to span one side of the rotor and a second side wall98that is mounted parallel to the first side wall96at the opposing end of the rotor. The first side wall is a continuous circular wall. The second side wall98is generally annular in shape having an outer diameter corresponding to the outer diameter of the first side wall, but including a central aperture100concentric with the outer diameter that defines a fan inlet opening through which air enters into the rotor in operation.

The rotor vanes94extend axially between the first side wall96and the second side wall98at evenly spaced apart positions in the circumferential direction. Each rotor vane94extends between an inner end at the inner boundary of the central opening100in the second side wall98to an outer end at the outer boundary of the body of the rotor. Each rotor vane extends outward from the rotor axis in a trailing relationship relative to a respective radial axis that passes through the inner edge of the vane from the rotor axis. Each rotor vane has a convex leading face such that the rotor vane extends outward at an increasing slope relative to the respective radial axis. At the outer end portion of each rotor vane, the vane is oriented to be nearer to a tangential axis than a radial axis of the rotor.

The housing88of the vacuum device also includes a first side wall102lying perpendicular to the rotor axis which receives the first side wall96of the rotor in close proximity thereto. A drive shaft104is fixed to the first side wall96of the rotor and is supported by rotary bearings105to extend through the first side wall102of the housing which are in close proximity to one another while being supported for relative rotation therebetween. The housing also includes a second side wall106which is parallel and spaced apart from the first side wall by a thickness which is slightly greater than the corresponding dimension of the rotor such that the second side wall106of the housing and the second side wall98of the rotor are substantially flush with one another in the mounted position of the rotor within the housing. The second side wall of the housing is annular in shape having an outer edge aligned with the outer edge of the first side wall and a central opening108therein having an inner diameter which closely matches the outer diameter of the rotor received therein.

The stationary vanes90are supported in fixed relation to the housing such that each vane extends axially a full height between the first side wall102and the second side wall106. Each vane further extends radially from an inner edge at the boundary of the central opening108in close proximity to the outer boundary of the rotor, to an outer edge that is only partway towards the outer perimeter edge of the side walls of the housing. In this manner, a radial gap is provided between the outer edge of each stationary vane90and the outer perimeter of the housing. Each stationary vane90is flat. In some embodiments, each stationary vane90may lie along a respective radial axis91extending radially outward from the rotor axis; however, in the illustrated embodiment, the stationary vanes90each extend radially outwardly at a forward slope towards the direction of rotation at an angle X relative to the respective radial axis91that is between 20 and 30 degrees.

A perimeter wall110spans between the first side wall102and the second side wall106of the housing about the perimeter thereof. A gap is provided in the perimeter wall110in communication with a fan outlet duct112defining an outlet of the fan. The radial gaps between the outer edges of the stationary vanes90and the perimeter wall110form a perimeter duct extending about the perimeter of the housing.

A pulley member113is mounted on the outer end of the drive shaft104for connection to the rotary output of a suitable motor115using a drive belt. The motor115thus drives the rotation of the drive shaft104and the rotor92connected thereto relative to the housing of the fan.

When the rotor is rotated, the rotor vanes94urge a flow of air radially outward into the passages between the stationary vanes90which in turn draws a flow of air inwardly into the fan inlet at the centre of the rotor to apply a vacuum pressure to the exhaust duct connected thereto. As the rotor vanes urge airflow radially outward through the stationary vanes, the air entering the circumferential perimeter duct within the housing is directed circumferentially about the housing towards the fan outlet duct112which is oriented in a tangential direction relative to the rotor axis to extend forwardly in the flow direction corresponding to the direction of rotation of the rotor about the circumference of the housing. The rotating vanes draw air in from the centre and distribute the flow radially outward. This air is redirected by the stationary vanes for compressing the air and sending it outward into the housing and out the fan outlet opening in the side of the housing.

The function of the fan is to produce a negative pressure environment with a modest airflow through the envelope in the bin structure. The number of vanes, the rate of rotation, and the length and width of the fins will vary depending upon the required vacuum pressure, the volume of the bin, and the resulting flow rate required. The fan rotor may be belt driven by an electric motor, or in certain conditions may be driven by a combustion engine.

The apparatus10further includes one or more sensors114supported internally within the envelope in the bin structure. The sensors114may be configured for sensing temperature and/or pressure within the interior of the envelope. The resulting sensor signals provide an indication of temperature or pressure communicated to an external controller116.

The controller116is a computer device comprising a processor and a memory storing programming instructions thereon which are executable by the processor for performing various functions as described herein. For example, the controller may store one or more temperature thresholds and one or more pressure thresholds which are used to monitor operation of the apparatus for drying particulate material.

The controller may be further configured for generating control signals that are directed towards an actuator associated with the flow restrictor valve22, an actuator associated with the control valve86, and the motor associated with the vacuum device20which may operate the vacuum device between on and off positions or at a selected one of numerous variable speeds. The controller can operate the valves and the fan according to various operating parameters, and uses the sensed temperature and/or pressure as an input to control the operation of the apparatus.

In one instance, the temperature as measured by the sensors114may be monitored by the controller such that the controller is arranged to generate an alert communicated over a communications network to a personal computer device of a user if the sensed temperature meets a stored temperature threshold, so that the user can take appropriate action if required. Alternatively, the controller may be arranged to automatically cease the operation of the vacuum device or change the operating parameters thereof if a certain temperature threshold is met.

The temperature sensors may be supported within the bin on the supports for the manifold ducts. Electrical leads may communicate through the bin floor to the external controller. The controller may monitor for a drop in temperature which is indicative of a drop in moisture content. For example, a drop in 1% in moisture content may correspond to a drop of 5.4 degrees Celsius.

In operation, the control valve within the exhaust duct can be initially used to control the airflow and control the load to the motor driving the fan. Upon initial activation of the vacuum device, the control valve86can be partly opened, but as the pressure in the bin is reduced, subsequently further opened all the way, so that flow and pressure is later controlled by the flow restriction valve22during sustained operation.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.