Abstract:
An aggregate bin heater assembly having a bin for receiving aggregate therein and a plurality of fluid inlets supported at vertically spaced apart elevations relative to the bin for distributing a heating fluid into the aggregate within the bin, further includes a control system for controlling distribution of the heating fluid. A pressure sensor associated with at least an uppermost one of the fluid inlets so as to be arranged to sense pressure within the bin at the respective elevation. A controller determines a low pressure condition if the pressure sensed by the pressure sensor is lower than a prescribed normal pressure. A valve associated with the uppermost one of the fluid inlets shuts off the flow of heating fluid to the uppermost one of the fluid inlets responsive to determination of the low pressure condition by the controller.

Description:
[0001]    This application claims the benefit under 35 U.S.C. 119(e) of U.S. provisional application Ser. No. 61/937,082, filed Feb. 7, 2014, and U.S. provisional application Ser. No. 61/969,555, filed Mar. 24, 2014. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a system for monitoring pressure of a fluid percolated through a bulk material within a particulate material storage bin, for example in one embodiment the system may measure the pressure of a flow of conditioning fluid such as heated air which is pressurized to flow through the aggregate to be conditioned in the bin. In an alternative embodiment the system may measure the pressure level of a pressurized flow of an auxiliary fluid such as compressed air which flows through the particulate material in the bin, whereby a loss in back pressure in the flow of the fluid is indicative of an absence of material at the monitored elevation. The monitored pressure thus permits a height of the particulate material within the bin to be monitored, and in the instance of an aggregate conditioning bin also permits the flow of conditioning fluid injected into the aggregate to be controlled to prevent wasteful distribution of conditioning fluid to upper portions of the bin whenever the level of the material inside the bin is lower than the level at which the heating fluid is injected. 
       BACKGROUND 
       [0003]    In colder climates, where aggregate is often stored below freezing temperatures, it is generally known to heat aggregate to ensure that water does not freeze in contact with the aggregate when mixing with concrete. 
         [0004]    A known type of aggregate heater is an air heated bin in which a bin structure having an open top end for loading and a hopper at a bottom end for discharge further includes a plurality of fluid inlets at different elevations for diffusing the hot air through the aggregate in the bin. One example of a bin heater system of this arrangement is described in U.S. Pat. No. 3,659,583 by Martin. 
         [0005]    In a typical aggregate condition bin, the level of material in the bin is highly variable since the feeding of material to the bin and the consumption of the material from the bin are not constant and equal rates. When using known heater systems of the type described above, air follows the path of least resistance through the aggregate. Accordingly, if the variable level of aggregate material within the bin falls below the uppermost fluid inlets, the heated air primarily escapes to atmosphere through the exposed fluid inlets rather than being used effectively to heat the aggregate. 
         [0006]    It is also desirable to keep the bin close to being full for optimal use of the heated air, but few reliable means are known for monitoring the height of the entire top surface of the aggregate in the bin. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one aspect of the invention there is provided a control system for an aggregate conditioning bin assembly having a bin for receiving aggregate therein and a plurality of fluid inlets supported at vertically spaced apart elevations relative to the bin for distributing a conditioning fluid into the aggregate within the bin, the control system comprising: 
         [0008]    a height monitor arranged to determine if height of the aggregate is below one or more fluid inlets of the uppermost elevation; 
         [0009]    a controller arranged to determine a low level condition if said height is below the one or more fluid inlets of the uppermost elevation; 
         [0010]    a valve associated with the one or more fluid inlets of the uppermost elevation so as to be arranged to shut off a flow of conditioning fluid to the one or more fluid inlets of the uppermost elevation responsive to determination of the low level condition by the controller. 
         [0011]    According to second aspect of the invention there is provided a control system for an aggregate bin heater assembly having a bin for receiving aggregate therein and a plurality of fluid inlets supported at vertically spaced apart elevations relative to the bin for distributing a heating fluid into the aggregate within the bin, the control system comprising: 
         [0012]    a pressure sensor associated with an uppermost one of the fluid inlets so as to be arranged to sense pressure of the heating fluid within the bin at the respective elevation; 
         [0013]    a controller arranged to determine a low pressure condition if the pressure sensed by the pressure sensor is lower than a prescribed normal pressure; 
         [0014]    a valve associated with the uppermost one of the fluid inlets so as to be arranged to shut off a flow of heating fluid to the uppermost level of the fluid inlets responsive to determination of the low pressure condition by the controller. 
         [0015]    By monitoring the pressure of at least an uppermost elevation in particulate material storage bin equipped with fluid inlets at different elevations, the drop in back pressure resulting from an absence of particulate material at the elevation being monitored by any pressure sensor can be used both i) to monitor height of the particulate material within the bin, as well as ii) in the case of an aggregate condition bin, to cease flow of conditioning fluid to elevations not occupied by aggregate for optimizing efficiency of the conditioning system. 
         [0016]    Preferably the prescribed normal pressure corresponds to a pressure indicative of a height of the aggregate being above said uppermost one of the fluid inlets. Typically the prescribed normal pressure is based upon ambient pressure. 
         [0017]    The system preferably further includes at least one secondary sensor associated with another respective one of the fluid inlets so as to be arranged to sense pressure of the heating fluid at the respective elevation. A valve is preferably also arranged to be in communication with the associated fluid inlet of said at least one secondary sensor so as to be arranged to shut off a flow of heating fluid to that fluid inlet responsive to determination of a low pressure condition associated with that fluid inlet. 
         [0018]    When the system further includes a pressure tube extending between a first end arranged to communicate with the heating fluid in the aggregate within the bin at the respective elevation of the uppermost one of the fluid inlets and a second end which is external of the bin, the pressure sensor is preferably in communication with the second end of the pressure tube. 
         [0019]    Each fluid inlet preferably communicates with a diffuser element extending generally horizontally through the bin. Preferably the first end of the pressure tube is arranged to communicate with the heating fluid within the diffuser element. 
         [0020]    The heating fluid typically comprises air, however, the heating fluid may alternatively be conditioning fluid such as steam or air with a prescribed moisture content. 
         [0021]    Each pressure sensor is preferably arranged to sense pressure of the heating fluid within the bin at the respective elevation. 
         [0022]    According to a further aspect of the present invention there is provided a height monitoring system for an aggregate storage bin arranged for receiving aggregate therein, the system comprising: 
         [0023]    a plurality of fluid inlets arranged to be supported at vertically spaced apart elevations relative to the bin for distributing a pressurized fluid into the aggregate within the bin; 
         [0024]    a pressure sensor associated with at least one of the fluid inlets so as to be arranged to sense pressure of the pressurized fluid within the bin at the respective elevation; and 
         [0025]    a controller arranged to determine a low pressure condition of said at least one fluid inlet if the pressure sensed by the pressure sensor of said at least one fluid inlet is lower than a prescribed normal pressure; 
         [0026]    whereby a height of the aggregate is determined to be below said at least one fluid inlet responsive to a determination of the low pressure condition of said at least one fluid inlet. 
         [0027]    The pressure sensor of said at least one fluid inlet is preferably arranged to sense pressure of the pressurized fluid within the fluid inlet prior to the fluid entering the aggregate. 
         [0028]    Preferably said at least one fluid inlet includes at least one diffuser element spanning horizontally across the bin such that said at least one diffuser element communicates with aggregate in the bin at various locations across the respective elevation of the fluid inlet. Preferably the pressure sensor is arranged to sense pressure within said at least one diffuser element. 
         [0029]    Preferably the diffuser elements are shaped to prevent accumulation of the aggregate thereon by being open only in a generally downward direction into the bin. 
         [0030]    Preferably the pressurized fluid is introduced into the diffuser element at a location which is horizontally spaced apart from a sensing location which is in communication with the pressure sensor. 
         [0031]    The pressurized fluid typically comprises a compressible fluid, however, a non-compressible conditioning fluid may be used in some instances. 
         [0032]    In some embodiments, a pressure sensor is associated with one fluid inlet at each respective elevation of the bin. 
         [0033]    Preferably said at least one of the fluid inlets is arranged such that pressurized fluid is introduced into the fluid inlet at a supply location which is horizontally spaced apart from a sensing location which is in communication with the pressure sensor and such that the fluid inlet is in communication with the aggregate between the supply location and the sensing location. 
         [0034]    Various embodiments of the invention will now be described in conjunction with the accompanying drawings in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a perspective view of the control and monitoring system applied to a heater bin. 
           [0036]      FIG. 2  is a side elevational view of the bin according to  FIG. 1 . 
           [0037]      FIG. 3  is an end elevational view of the diffuser arrangement in the bin according to  FIG. 1 . 
           [0038]      FIG. 4  is an end elevation view of one of the diffuser elements in the bin according to  FIG. 1  with one of the pressure ports in the bin wall shown in relation to the diffuser element. 
           [0039]      FIG. 5  is a cross sectional view through one of the pressure ports in the bin wall. 
           [0040]      FIG. 6  is an elevational view of a pressure tube and fitting for threaded connection within one of the pressure ports in the bin wall. 
       
    
    
       [0041]    In the drawings like characters of reference indicate corresponding parts in the different figures. 
       DETAILED DESCRIPTION 
       [0042]    Referring to the accompanying figures, there is illustrated an aggregate bin control and monitoring system generally indicated by reference numeral  10 . The system  10  is particularly suited for use with an aggregate heater bin  12 . 
         [0043]    In the illustrated embodiment, the bin  12  includes two upright side walls  14  and two end walls  16  joined between the side walls at longitudinally opposed ends. In this manner, the walls define a full perimeter containment spanning between an open top end  18  of the bin through which aggregate may be loaded to a bottom end  20  locating a hopper with a gate mechanism to control the discharge of aggregate therethrough. 
         [0044]    The bin further includes a plurality of diffuser elements  22  spanning horizontally across the bin at each of three different elevations. At each elevation, at least one diffuser element  22  extends longitudinally between the two end walls  16  and a plurality of diffuser elements  22  span laterally between the opposing two side walls  14 , perpendicularly across the longitudinal diffuser elements. 
         [0045]    Each diffuser element  22  comprises a rigid elongate channel which is formed by bending a flat plate and which is inverted in orientation. Accordingly, each channel defines two depending side flanges  24  and a bridge portion  26  connected between the top ends of the side flanges such that the resulting diffuser element remains open along the bottom thereof along the full length between opposing walls of the bin. 
         [0046]    The bridge portion is formed with an apex with the remainder of the diffuser element being sloped downwardly therefrom to prevent accumulation of any material on the diffuser elements. The downwardly open arrangement of the diffuser elements also prevents accumulation of any material within the diffuser elements. 
         [0047]    At each elevation, all of the diffuser elements of that elevation communicate with one another so that the diffuser elements collectively communicate with the surrounding material at various locations as a common diffuser network spanning across the bin at the respective elevation. One end of one or more diffuser elements of each diffuser network at a respective bin level communicates with a fluid inlet port  28  formed as a port communicating through the corresponding wall of the bin. 
         [0048]    All of the fluid inlet ports  28  are supplied with a pressurized flow of conditioning fluid, for example heater air supplied by a heated air supply  30  in the instance of a heater bin. In the instance of other conditioning bins, for example for drying aggregate, the pressurized flow of conditioning fluid may take the form of compressed air for drying the aggregate. 
         [0049]    In this manner, when the bin is full and a heating cycle is activated, air is heated and distributed under pressure by a blower of the heated air supply  30  through a suitable manifold structure to be injected into the bin through the various ports. The flow of heated air extends along all of the diffuser elements of each diffuser network associated with each inlet port such that the inlet port and the associated diffuser elements collectively define the fluid inlet for the respective elevation from which the conditioning fluid is subsequently diffused into the surrounding aggregate, followed by being exhausted upwardly through the open top end of the bin. 
         [0050]    The control and monitoring system  10  typically includes a plurality of pressure sensors  32  with at least one sensor typically being associated with each of the multiple elevations of the diffuser elements. Each pressure sensor  32  communicates with a respective pressure tube  34  which communicates between the interior of the bin and the exterior of the bin where the corresponding pressure sensor is located. 
         [0051]    More particularly, each pressure tube  32  extends through the bin wall through a respective pressure port  36  formed in the wall. Each diffuser element having a pressure sensor associated therewith typically locates the pressure port  36  in the bin wall at a location which is horizontally opposed from the associated fluid inlet port  28 . The pressure tube is arranged to extend from a first end  38  located centrally along the length of the respective diffuser element directly below the bridge portion  26 . The pressure tube and the sensor communicate with the respective inlet through the one or more diffuser elements forming the associated diffuser network. The pressure tube and sensor are thus located in communication with the fluid while it still remains within the collective fluid inlet defined by the associated diffuser network at a common elevation with one another, and prior to diffusion of the fluid into the surrounding aggregate. 
         [0052]    In this instance, each diffuser network defines a respective fluid inlet having a supply location and a sensing location which are horizontally spaced apart from one another such that fluid in the diffuser network is permitted to communicate with and diffuse into the surrounding aggregate between the supply location and the sensing location. The supply location is defined as the inlet port in the side wall of the bin where the pressurized fluid is first introduced into the diffuser network. The sensing location is defined as the first end  38  of the pressure tube of the respective pressure sensor associated with the diffuser network at the same horizontal elevation. 
         [0053]    A first leg  40  of the tube extends horizontally from the first end  38  through the pressure port  36  for connection to a second leg  42  which extends downwardly along the outer side of the corresponding bin wall. The second leg terminates at a bottom end defining a second end  44  of the tube which is in communication with the respective pressure sensor  32 . 
         [0054]    At each pressure port  36 , the bin wall includes an internally threaded socket secured to the outer side of the bin wall which defines a female coupling  46 . The pressure tube includes a corresponding threaded male coupling  48  located at the end of the first leg in proximity to the second leg such that threaded connection between the male coupling  48  and the female couple  46  provides a sealed connection of the pressure tube  34  relative to the pressure port  36  receiving the tube therethrough. 
         [0055]    Each level has one or more valves  50  associated therewith which are in communication in series between the heated air supply and all of the fluid inlet ports of the associated level. The valves are arranged to be opened and closed under control of a suitable controller  52 . 
         [0056]    The controller  52  functions to monitor pressure from all of the sensors  32 . The controller determines a normal prescribed pressure corresponding to the back pressure of heated air when the bin is full of aggregate. The normal prescribed pressure will be different for each different type of aggregate received in the bin as the resistance to the diffusion of the heated air upwardly through the aggregate to the open top of the bin will be different depending upon the size of the aggregate and thus the corresponding size of interspaces between particles of the aggregate. 
         [0057]    Once a normal prescribed pressure has been calibrated for the aggregate type located in the bin, the controller then continues to monitor the pressure from all sensors to determine if any low pressure conditions occur. The low pressure condition is determined when the monitored pressure of one of the sensors falls below the normal prescribed pressure by a lower limit or threshold amount. This is normally indicative of a situation where the level of aggregate in the bin falls below the elevation of the fluid inlets or diffusers monitored by one of the pressure sensors such that the resulting back pressure to the flow of heated air diffusing through the aggregate is reduced. Typically the normal prescribed pressure is derived from a measured ambient pressure. 
         [0058]    Height is determined by the controller to be below any sensor which is found to be in a low pressure condition. 
         [0059]    Furthermore, when a low pressure condition is determined at any monitored elevations of the bin, the controller actuates the corresponding valves to shut off the flow of heated air to all of the diffusers and fluid inlet ports associated with that elevation and any elevation thereabove to prevent the wasteful escape of heated air above the level of aggregate within the bin. 
         [0060]    In further embodiments, the control and monitoring system can be adapted for various other heated fluids including steam and the like. 
         [0061]    Furthermore, in some embodiments, only an uppermost elevation of fluid inlets may be monitored by pressure sensors to indicate that the bin requires filling above the uppermost level. Provided that the bin is maintained at a reasonable level in response to the indication by the monitoring system whenever the bin level falls below the uppermost level, additional elevations below the uppermost diffuser element may not be required to be monitored. 
         [0062]    In yet further embodiments, the system  10  may be used only as a height monitor in any type of particulate material storage bin, for example aggregate, plastics, grains, etc. simply by modifying the bin to provide vertically spaced apart pressure ports along one or more walls of the bin. In this instance the pressure ports communicate with pressure sensors monitored by a controller as described above and the different elevations are supplied with a flow of pressurized air such that the back pressure in the flow to each level is monitored. 
         [0063]    The control and monitoring system  10  is further adaptable to various sizes and configurations of bins as well as to various configurations of conditioning systems which supply a conditioning fluid at one or more elevations. 
         [0064]    Various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made without department from the spirit and scope of the invention. It is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.