GB2031291A - Pneumatic agitator/fluidizing device - Google Patents

Abstract

The device is in the form of a flexible, resilient member (30 or 64) fixed so that a marginal edge (36 or 68) is normally in contact with and defines an interface (38 or 70) with an associated surface. Air under pressure is fed (26 or 58) to the interface in such fashion as to cause the marginal edge of the resilient member to flutter and allow the air to escape in randomly directed "puffs". The fluttering movement combined with the intermittent puffs of air causes pulverulent material to be agitated, aerated and/or fluidized as it passes to the discharge opening (12) of a hopper (10) in which the device is mounted. <IMAGE>

Description

SPECIFICATION Aerator nozzle Pulverulent materials are commonly transported in and discharged from tank vehicles, the discharge being effected through a closed system to minimize contamination of the atmosphere by dust. The discharge of powdered materials such as cement is much easier if the material is aerated or fluidized before entering a piping system through which the product is pneumatically conveyed. The vehicles may be in the form of elongate, substantially horizontal tanks with one or more discharge hopper devices along their lower sides through which the product may migrate by gravity to the pneumatic conveying piping system, a portion of which may be carried by the vehicle itself.The interior of the tank may be pressurized to facilitate the discharge, and as above noted, the discharge is easier if the material is aerated or fluidized before entering the pneumatic conveying pipe system. A common means of achieving fluidization is to introduce air into the hopper of the tank through porous or similar elements, fluidization of the material adjacent the discharge mouth assisting in conveying the material to the discharge port.

These porous elements or pads exhibit certain undesirable characteristics, in particular their propensity to blinding due to the fact that the air passed therethrough normally contains a certain amount of foreign material or dust which gradually fills the pores of the material, which may be, for example, canvas. Also, these porous pads make it difficult to clean the hopper assembly.

However, without some form of aid, bulk products such as cement when discharged through the narrowed hopper outlet mouths tend to pack or bridge at these outlets and it is therefore relatively essential that some means be provided to aid in this discharge.

Accordingly, it is an object of the invention to provide means for decreasing the tendency of bulk products being discharged from a hopper structure to pack or bridge at the outlet The invention provides a device for agitating and aerating pulverulent materials comprising: a base member defining a supporting surface, a flexible resilient agitating member fixed relative to the base member and having a marginal portion contacting the support surface to define an interface therewith but free to flutter with respect thereto, and means for supplying air to the interface under sufficient pressure to cause the marginal portion of the agitating member to flutter so that it is intermittently out of contact with the supporting surface to allow air to escape past the supporting surface in discrete bursts.

The supporting surface may be an interior surface of a hopper assembly for storing pulverulent material which surface is arranged to channel the material to a discharge mouth through which the material may flow, a closed body of a vehicle for transporting pulverulent material may comprise a hopper assembly, and the vehicle may further comprise valve means for selectively opening and closing the discharge mouth, and a discharge line communicating with the discharge mouth through the valve means, the discharge line being adapted to receive pressurized air to convey material through the discharge line.

The agitating member is advantageously in the form of a frustro-conical sleeve fitted within the discharge mouth of the hopper, and an annular manifold preferably surrounds the discharge mouth, the discharge mouth being provided with a series of openings leading from the annular manifold to the interface.

The supporting surface may be annular and the agitating member of circular configuration. The base member advantageously includes an upright stem disposed centrally of the annular supporting surface, the agitating member having a central portion engaged on the stem. The base member preferably includes a series of bores surrounding the stem and air inlet means for delivering air to the bores. The base member and the agitating member may define an annular manifold chamber therebetween with which the bores communicate.

The agitating member may be provided with an annular recess at least partially defining the manifold chamber, and the base member may be provided with an annular recess at least partially defining the manifold chamber. The annular supporting surface may be a convex cone frustrum, whereby discrete bursts of air are directed outwardly and downwardly therefrom, or the annular supporting surface may be concave whereby the discrete bursts of air are directed outwardly and upwardly therefrom.

The invention also provides a hopper assembly comprising at least one device in accordance with the invention.

The invention also provides a vehicle for transporting pulverulent material, which comprises at least one such hopper assembly.

Several forms of device constructed in accordance with the invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a vertical section taken through the hopper outlet of a tank vehicle and through one form of the device; Fig. 2 is a vertical section taken through a hopper assembly showing a second form of device; Fig. 3 is a plan view of the underside of the device shown in Fig. 2; Figs. 4, 6, 8 and 10 are plan views of the base members of four further forms of the device; Figs. 5, 7, 9 and 11 are sectional views taken through the complete devices of Figs. 4, 6, 8 and 10, respectively; Fig. 12 is a plan view of a further form of device; Fig. 1 3 is a sectional view along the line 13-l3ofFig. 12;; Fig. 14 is a view similar to Fig. 13 but of a further form of device; Fig. 15 is a plan view of a further form of device; and Fig. 1 6 is a section along the line 1 6-1 6 of Fig. 1 5.

With reference to Fig. 1, an outlet hopper indicated generally by the reference numeral 1 0, which, it is to be understood, is of a construction conventional in bulk product tank vehicles, is provided with a discharge mouth 22 and as is indicated in phantom lines in Fig.1, associated therewith is a valve indicated generally by the reference numeral 14 which permits selective opening of the discharge mouth 12 to allow discharge of the material contained in the tank vehicle. The hopper structure 10 is usually one of several which are provided along the underside of the tank vehicle and the valve 14 forms an integral part of the vehicle structure as does a distribution pipe 16. The structure also includes a pipe stub 1 8 which discharges into the main line 16, all of which is conventional in the art.It is also conventional in these tank vehicles to provide a motor driven blower which not only discharges air into the outlet line 1 6 to allow fluid conveying of the material but also pressurizes the interior of the tank, thereby aiding in the expulsion of the material from the tank. It will be appreciated that at one end the distribution line 1 6 is connected to the user's distribution system for delivering the material to the desired site.

The pulverulent material contained in the tank vehicle may be a relatively fine powder such as cement and, for this reason, it may tend to pack or bridge over the discharge mouth 12, thus interrupting the efficient and steady flow of material to the discharge conveying pipe 1 6.

The hopper structure 10 is provided with a manifold formed by wall means 20 and having an interior 22 which is provided with a suitable connection (not shown) with the pressurized air system to maintain air under the requisite pressure within the manifold interior 22. Around the periphery of the hopper wall 24 is provided a series of circumferentially spaced openings 26 through which air may escape from the manifold.

Cooperatively associated with the discharge openings 26 is an agitating and aerating means which is indicated generally by the reference character 28 and which, in this form of device, takes the form of a frustoconical section of rubber or like material 30 engaging in face-to-face contact with the interior of the hopper wall 24 just adjacent to the discharge opening 12 and further including a central portion 32 which extends radially outwards in the the form of an annular flange around the discharge opening 1 2.

Thus, the member 30 includes an intermediate portion 34 which normally closes the manifold openings 26 and a marginal edge portion 36 lying flat against the interior of the hopper wall 24 to define an interface 38. If the pressure of the air within the manifold interior 22 is maintained at a proper value, air will be supplied to the interface 38 at a pressure sufficient to cause the marginal edge 36 of the agitating and aerating means 28 to flutter or vibrate with a consequent periodic or interrupted escape of air in the form of air jets directed upwardly along the inner surface of the hopper wall 24 and at random circumferential spacings therearound. The pressure of air maintained within the interior of the manifold 22 will ordinarily be of the order of 1 to 1 0 pounds per square inch gauge if the interior of the tank vehicle is under normal atmospheric pressure.If the interior of the tank vehicle is maintained under some higher pressure in order to expedite the discharge, then the pressure in the manifold 22 will ordinarily be of the order of 1 to 10 psi higher than that internal pressure. In either case, the air flow rate past the agitating and aerating means 28 will be of the order of from 10 to 400 standard cfm.

As described above, the agitating and aerating means 28 causes the escaping air to flow in random, interrupted fashion by the fluttering or vibrating action of the marginal edge portion 36 which occurs randomly around the periphery of the edge portions 36. As a result, not only is the pulverulent material agitated in the immediate vicinity of the discharge mouth 12, but also an aerating orfluidizing effect is produced, the net result being that a steady and efficient discharge flow of material is achieved.

Referring now to Fig. 2, the hopper structure which is of conventional nature is again indicated generally by the reference numeral 10 and includes the discharge opening or mouth 12 as described hereinbefore. A plurality of agitating and aerating devices are attached to the hopper wall 24 in circumferentially spaced relation to each other immediately above the discharge opening or mouth 12. Only one of these devices, which is indicated generally by the reference numeral 40, is illustrated in Fig. 2.

The device 40 comprises a metallic or otherwise rigid body member having a central stem portion 42 and a radially projecting disc portion 44. The stem portion 42 projects upwardly from the disc portion 44 and terminates in an enlarged retaining head 46. The underside of the stem 42 is provided with a threaded bore 48 which receives a bolt 50 by means of which a cap member 52 is secured to the body. The hopper wall 24 is provided with an opening which receives the assembly with the disc portion 44 on the inside thereof and the cap portion 52 on the outside, there being suitable sealing gaskets 54 and 56 positioned as shown so that when the bolt 50 sandwiches the hopper wall 24 between the two members, the opening is sealed off. The body member is provided with a plurality of through bores 58 which communicate the upper side of the disc portion 44 with the interior of the cap portion 52 and the cap portion 52 is provided with a suitable outlet opening 60 and associated nipple portion 62 for connection to a source of pressurized air. A resilient body indicated generally by the reference numeral 64 includes a generally cylindrical central portion 66 which snugly fits the stem portion 42 immediately below the retaining head 46 and a skirt portion projecting radially outwards from the central portion to terminate in an outer marginal edge portion 68 which seats upon a slightly inclined frustro-conical surface 70 of the body member outboard of the openings 58.

The body member is bevelled slightly as is indicated by the reference numeral 72 in the region of the bores 58 to form a manifold space 74 immediately underlying an intermediate portion 76 of the resilient skirt.

The operation of the device shown in Fig. 2 is essentially the same as that of that shown in Fig.

1. That is to say, air is supplied to the interior of the cap 52 through the opening 60 in such manner as to ensure that the air in the interior of the cap 60 is maintained under sufficient pressure to cause fluttering or vibration of the marginal edge portion 68 of the resilient member 64, again to provide intermittent puffs or jets of air to be expelled at random circumferentially spaced positions. One feature of the device shown in Fig.

2 is the fact that the interface 70 is downwardly inclined in an outward direction as illustrated to direct the puffs of air toward the inner surface of the wall 24. As shown in Fig. 3, the underside of the disc 44 is provided with a series of fingers 78 which project outwardly somewhat to separate the spaces between adjacent through bores or openings 58.

Figs. 4 to 11 illustrate four further forms of device. In Figs. 4 and 5 a support member 82 which corresponds to the disc 44 in Fig. 2 is provided with a flat marginal edge surface 84 on its skirt portion 86 and is provided with a central recess portion 88 surrounding a stem 90. As before, the stem 90 terminates in an enlarged head portion 92 which serves to retain the central cylindrical portion 94 of the flexible member such that its skirt 96 is normally retained in face-to-face contact against the surface 84 to provide an interface 100 thereat. Through bores 98 are provided and these lead to the recessed portion 88 which provides a manifold space.Thus, the pressurized air is uniformly supplied around the circumference of the interface 100 to produce the random vibrating and fluttering action and the concomitant intermittent and randomly directed jets of air as previously described.

In contrast, in the device shown in Fig. 6 and 7 the flexible member 102 is itself provided with an annular recess 104 whereas the disc 106 has an entirely flat surface 108 which with the recess 104 defines the manifold space 110. Again, a uniform circumferential distribution of pressurized air is applied to the interface 112. Additionally, in this embodiment, the narrowed thickness of the intermediate portion 114 of the flexible member 102 allows a more lively action for the outer marginal edge portion.

In a further form of device which is shown in Figs. 8 and 9 both the disc portion of the support member and the intermediate portion of the resilient member are recessed and these two recesses 11 6 and 118, respectively, together define a manifold space 1 20.

Lastly, in the device shown in Figs. 10 and 11, the support body is provided with a flat surface 122 and the underside of the flexible skirt 1 24 is also flat so that there is no manifold space between them. However, in this case, a plurality of closely spaced and circumferentially distributed through bores 126 achieve essentially the same effect as the manifold space previously described but, again, the cooperation is such as enhances the random jetting effect previously described.

Referring to Figs. 12 and 1 3, the body 126 of a further form of device has an outwardly extending flange 1 38 with lugs 1 40. The body 1 26 is clamped to the outside of the hopper wall 10 by bolts 144 with wingnuts 1 46 passing through bores 142 in the lugs 1 40. The body 126 projects through an aperture in the wall 10 which is seaied by a gasket 1 50 between the flange 1 38 and the wall.The part of the body which is inside the hopper has a stem 128 with an enlarged head 1 30 retaining a central portion 132 of a resilient member which has a skirt portion the outer edge 134 of which lies flat against the body 126 to form an interface 136, as previously described forms of device. This form of device is very easy to dismount from the hopper wall.

In another form of device, which is shown in Fig. 14, the agitating and aerating means is mounted on a door assembly indicated generally by the reference numeral 1 52. The door construction is hollow as indicated to provide an interior air chamber 1 54 and is provided with a suitable releasable clamping means indicated generally by the reference character 1 56 by means of which the door can be held shut with a sealing gasket 158 forming a seal between the door and the body of the hopper. The door is provided with an inlet pipe 160 by means of which pressurized air is introduced into the chamber 154 and the inner wall 162 of the door is provided with a series of openings 164 through which air can pass into a manifold space 1 66 formed by an undercut intermediate portion 1 68 of a flexible skirt 170.The wall 1 62 is dished as shown in the outer marginal edge 1 72 of the flexible skirt is normally in face-to-face contact therewith, as shown, so that the jets of air which escape around the periphery of the flexible skirt are directed upwardly and outwardly. The door carries a stud 174 which is threaded at its outer end 1 76 to receive a nut 1 78 and washer 1 80 serving to anchor the central portion 182 of the flexible device to the door.

Figs. 1 5 and 1 6 illustrate a particular form of the invention which is suitable for replacing the circular porous pads which are currently employed for aeration purposes, as mentioned hereinbefore.

To this end, a metal plate 1 82 is provided with a series of circumferentially spaced holes 1 84 so that this metal plate may be bolted to the interior of a hopper in the fashion that the currently employed porous pads are attached thereto. The conventional manifold structure or source of pressurized air is not shown in Figures 1 5 and 1 6 but it is to be understood that a closed chamber underlies the plate 182 from which the pressurized air is supplied through openings 1 88 to manifold spaces 190 of three agitating and aerating devices indicated generally by the reference numerals 192,194 and 196.These are similar to previously described forms of device, having central portions 198 of resilient members anchored on stems 200 with intermediate portions 202 thereof overlying the manifold spaces 190 and outer marginal edge portions 204 thereof seated against the surface of the plate 182.

The disposition of the three assemblies 192, 194 and 196 on the plate 192 is such that together they produce an aerating effect over the entire area of the plate 182. In this regard, it will be appreciated that the flow of air to a particular device 192, 194 or 196 as in all of the embodiments of the invention and the pressure of the air supplied to the interfaces thereof depend to some degree upon the size of the flexible skirt portions. Typical sizes of the skirt are from 3 to 8 inches in diameter for a circular configuration such as is shown, for example, in Figs. 1 5 and 1 6 and typical flow rates per aerator will be from 10 to 400 standard cubic feet per minute with a typical pressure drop when discharging into normal atmospheric pressure being from 1 to 10 psig. In any event, the pressure of the air and the flow rate thereof are adjusted to cause the fluttering or vibrating effect in all instances whereby randomly directed and intermittent puffs or jets of air are expelled by reason of this fluttering or vibrating action.

Claims (18)

CLAIMS:

1. A device for agitating and aerating pulverulent materials comprising: a base member defining a supporting surface, a flexible, resilient agitating member fixed relative to the base member and having a marginal portion contacting the supporting surface to define an interface therewith but free to flutter with respect thereto, and means for supplying air to the interface under sufficient pressure to cause the marginal portion of the agitating member to flutter so that it is intermittently out of contact with the supporting surface to allow air to escape past the supporting surface in discrete bursts.

2. A device as claimed in claim 1, wherein the supporting surface is an interior surface of a hopper assembly for storing pulverulent material which surface is arranged to channel the material to a discharge mouth through which the material may flow.

3. A device as claimed in claim 2, wherein a closed body of a vehicle for transporting pulverulent material comprises the hopper assembly.

4. A device as claimed in claim 3, wherein the vehicle further comprises valve means for selectively opening and closing the discharge mouth, and a discharge line communicating with the discharge mouth through the valve means, the discharge line being adapted to receive pressurized air to convey material through the discharge line.

5. A device as claimed in any one of claims 2 to 4, wherein the agitating member is in the form of a frusto-conical sleeve fitted within the discharge mouth of the hopper.

6. A device as claimed in claim 5, including an annular manifold surrounding the discharge mouth, the discharge mouth being provided with a series of openings leading from the annular manifold to the interface.

7. A device as claimed in claim 1 , wherein the supporting surface is annular and the agitating member is of circular configuration.

8. A device as claimed in claim 7, wherein the base member includes an upright stem disposed centrally of the annular supporting surface, the agitating member having a central portion engaged on the stem.

9. A device as claimed in claim 8, wherein the base member includes a series of bores surrounding the stem, and air inlet means for delivering air to the bores.

10. A device as claimed in claim 9, wherein the base member and the agitating member define an annular manifold chamber therebetween with which the bores communicate.

11. A device as claimed in claim 10, wherein the agitating member is provided with an annular recess at least partially defining the manifold chamber.

12. A device as claimed in claim 10 or claim 11, wherein the base member is provided with an annular recess at least partially defining the manifold chamber.

1 3. A device as claimed in any one of claims 7 to 12, wherein the annular supporting surface is a convex cone frustrum, whereby discrete bursts of air are directed outwardly and downwardly therefrom.

14. A device as claimed in any one of claims 7 to 12, wherein the annular supporting surface is concave whereby the discrete bursts of air are directed outwardly and upwardly therefrom.

1 5. In a vehicle for transporting pulverulent materials and having a hopper-like discharge portion provided with a discharge opening, the combination of: means for simultaneously mechanically agitating the pulverulent material adjacent the discharge opening while intermittenty discharging randomly oriented discrete bursts of air into such material.

1 6. A device for agitating and aerating pulverulent materials substantially as hereinbefore described with reference to, and as shown in, Fig.

1 , or Figs. 2 and 3, or Figs. 4 and 5, or Figs. 6 and 7, or Figs. 8 and 9, or Figs. 10 and 11, or Figs. 12 and 13, or Fig. 14,orFigs. 15 and 16 ofthe accompanying drawings.

1 7. A hopper assembly comprising at least one device as claimed in any one of claims 1 to 1 6.

18. A vehicle for transporting pulverulent material, which comprises at least one hopper assembly as claimed in claim 1 7.