GB2072608A

GB2072608A - Particulate transfer apparatus

Info

Publication number: GB2072608A
Application number: GB8011099A
Authority: GB
Original assignee: British Ceca Co Ltd
Current assignee: British Ceca Co Ltd
Priority date: 1980-04-02
Filing date: 1980-04-02
Publication date: 1981-10-07

Abstract

Particulate transfer apparatus is provided which includes an open topped container having a side wall and a base with an outlet spout 4 extending from the side wall with the longitudinal axis of the spout horizontally or inclined with its free end upwardly. A gas inlet pipe 15 is located in the outlet spout, and through this inlet gas is obtained for mixture with the particulate and the mixture passes through the outlet spout. A fluidising plate (25, Figure 3) may also be provided, controlled by a valve (32). This valve is preferably operated alternately with the operation of valves (16, 26) controlling the outflow of the mixture. <IMAGE>

Description

SPECIFICATION Particulate transfer apparatus This invention relates to an apparatus and a process for transferring particulate.

According to one aspect of the present invention there is provided a particulate transfer apparatus, including a container having an open top, at least one side wall and a base, a particulate outlet spout located on the side wall of the container such that the longitudinal axis of the spout is horizontal or inclined with the free end of the spout upwardly, and a gas inlet located in the outlet spout such that in operation gas is mixed with the particulate and the mixture passes from the outlet spout.

In a preferred particulate transfer apparatus the gas inlet extends into the outlet spout by an amount equal to at least one and one quarter times the outside diameter of the outlet spount and the base of the container is angled relative to said at least one side wall so the inner face of the base faces the outlet spout. Preferably, the longitudinal axis of the spout is perpendicular to the base.

The gas inlet pipe is preferably arranged to extend from the outlet spout through and outwardly from the container, and conveniently through the base, the end of the gas inlet pipe extending through the base being connected to a gas control valve. The gas control valve may be a needle valve and to ensure accurate control of gas flowing through the inlet pipe a flowmeter is advantageously connected to the gas inlet pipe.

The particulate transfer apparatus preferably has an adaptor which is connected to the top of the container. The adaptor may be provided with an air vent to prevent collapse of a big bag for example from which particulate is discharged into the particulate transfer apparatus.

The container may be tubular with a circular cross-section and may conveniently be provided with a frame on which the container is mounted.

Rollers or castors can be provided on the frame to ensure manoverability.

Advantageously the outlet spout of the particulate transfer apparatus is connected to a diaphragm pump, the output from which is connected to receiving means such as a hopper or big bag.

The base of the container may be provided with a fluidizing plate and a pinch valve is connected to the outlet spout, the pinch valve being controlled so that it is closed prior to the operation of the fluidizing plate.

According to a further aspect of the invention there is provided a process of transferring particulate, including feeding particulate into a container having an open top, at least one side wall and a base, removing particulate through an outlet spout located on the side wall of the container such that the longitudinal axis of the spout is horizontal or inclined with the free end of the spout upwardly, and simultaneously mixing gas from a gas inlet pipe in the outlet spout so that a mixture of gas and particulate are removed from the outlet spout.

Preferably, the flow of gas through the gas inlet is measured with a flowmeter and is controlled by adjusting a gas control valve to obtain the required gas flow reading on the flowmeter. The gas inlet pipe is preferably vented to the atmosphere.

In a preferred process according to the invention the mixture of particulate and gas is removed from the container by a diaphragm pump. The pump can be operated by compressed air, hydraulically or electrically.

In order to avoid bridging of particulate within the container of the particulate transfer apparatus, the particulate is fluidized by a fluidizing plate located in the base of the container. Preferably, a pinch valve connected to the outlet spout is closed prior to operating the fluidizing plate.

By the term particulate as used herein is meant particles having a size less than 1 mm across.

Embodiments of particulate transfer apparatus in accordance with the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a particulate transfer handling system including particulate transfer apparatus according to the present invention.

Figure 2 is a side elevational view of one embodiment of a discharge apparatus according to the present invention, and Figure 3 is a side elevational view of a second embodiment of a particulate transfer apparatus according to the present invention.

The apparatus shown in the Figures is principally intended for transferring particulate such as a powder which may be volcanic rock of 0.6mm diameter, known as Perlite, from a silo or big bag to another silo or big bag at a different height or location in a substantially dust free manner. Alternatively, the powder may be fine powder having a density of 200kg/m3, such as that known as Clarcel Flo.

In this specification the term big bag refers to bags made of paper, fabric or synthetic material, which may have a liner of plastics material and which are of such size as to enclose a volume of at least 1 m3.

More particularly, Figure 1 shows a silo 1 which may be a hopper, big bag or other transportable container which is coupled by an adaptor 2 to a particulate transfer apparatus 3 having an outlet spout 4 connected by a flexible hose 5 to a pneumatically operatable diaphragm pump 6. The output from pump 6 is fed by a further flexible tube 7 to a hopper 8.

In order to obtain passage of powder through flexible tubes 5,7 and the diaphragm pump 6 this invention provides a small quantity of air be mixed with the powder. The mixing of air and powder is important since if there is too much air the powder will not compact sufficiently in the receiving hopper or big bag, resulting in an sufficient amount by weight of powder in a particular bag size. Alternatively, additional apparatus is required to ensure that the powder is shaken to remove the air. Too little air introduced into the powder prior to passage to the pump will inevitably result in compacting of the powder within the pump resulting in or no very inefficient transfer of powder to the receiving container.

To overcome the difficulties a particulate transfer apparatus 3 is provided, which can be more clearly seen in Figure 2. In Figure 2 the apparatus 3 is mounted on a frame 10 having four legs 11 in spaced relationship and being interconnected by cross members 12. Although not shown for the sake of clarity, the rigidity of the frame 10 is enhanced by tie members extending between the legs 11 in the region of the bottom of the legs. The apparatus 3 is connected to the top members 12 by a flange 13 in any conventional manner. The particulate transfer apparatus comprises a tubular container having a circular cross-section and a base 14.As shown in Figure 2 the base 14 extends at an angle of 45" to the longitudinal axis of the tubular container and in this manner assists the flow of powder passing into the container towards outlet spout 4 which is fixed to the side wall of the container. The longitudinal axis of the outlet spout 4 projects upwardly at an angle of approximately 45" to the longitudinal axis of the tubular container and is perpendicular to the base 14.

Located within the spout 4 is a pipe 15 which extends backwardly through the discharge unit and outwardly through the base 14. Pipe 15 serves as an air inlet pipe and is open at the free end of the outlet spout 4, flush with the end of pipe 4. In order to control the amount of air passing along inlet pipe 15 a fluidizing air inlet control valve 16 is provided in the inlet pipe which extends through the base 14 of the container. The air inlet pipe 15 is connected also to an air flowmeter 17 mounted externally on the container and is vented to the atmosphere. Accordingly, the amount of air which passes through the inlet pipe 15 can be accurately controlled by regulating the airflow shown on the airflowmeter 17 with the valve 16. The air inlef control valve is a needle valve.

In a practical form of the particulate transfer apparatus the outlet spout 4 has an outside diameter of approximately 3 inches (7.5cm) and extends approximately 6 inches (15cm) from the side wall of the particulate transfer container 3. The inlet pipe 15 has an outside diameter of 1 inch (2.5cms) while the diameter of the main body of the particulate transfer apparatus is 45cms. The frame 10 is formed from 2x2 inches (5cms x Scms) angle frame work and has a height of approximately 60cms and a width of 70cms.

In one alternative form of the particulate transfer apparatus the lowermost ends of the legs of the frame are provided with rollers or castors to allow manouverability of the apparatus. However, although it would be possible to connect a silo or big bag directly to the particulate transfer apparatus it is preferable to include the adaptor 2 which bolts onto the apparatus at the flange 13. The adaptor 2 has the same diameter as the container of the particulate transfer apparatus 3 and extends upwardly to its open end 20.

When the particulate transfer apparatus is to be used with a silo the adaptor 2 is constructed at its open end for connection to the discharge opening of the silo. Although not shown such a silo is provided 3t its discharge opening with a Mucon iris valve which prevents discharge of the powder in the silo from the silo discharge opening when the particulate transfer apparatus and adaptor 2 are disconnected from the silo.

When the apparatus 3 and adaptor 2 are used with big bags the bag is hoisted with its discharge opening hanging downwardly above the apparatus 3. Such big bags are tied at their discharge outlet to prevent discharge of the powder therein, but with sufficient extension of the discharge outlet, as shown in broken lines in Figure 2, to passoverthe adaptor 2. The part of the bag over the adaptor 2 is tied to the adaptor by a metal strap, for example, whereupon the initial tie on the bag is released to allow the powder to flow from the bag into the fluid transfer apparatus. It is to be noted that, where a big bag is used, the adaptor 2 is vented to the atmosphere through a flexible tube 22 and a vent filter 23 (Figure 1).The purpose of this vent is to prevent collapse of the big bag, otherwise caused by vacuum within the bag as the powder discharges from the bag.

It has been found that the mixing of powder and air is best achieved when the inlet pipe 15 is flush with the end of the outlet spout 4. As indicated in Figure 1, the outlet spout 4 is connected to the diaphragm pump 6 by the flexible pipe 5. The diaphragm pump 6 is pneumatically operated and its operation is such as to suck powder from the container of the particulate transfer apparatus through the outlet spout 4. Such suction is also effective to suck air through the inlet pipe via the flowmeter 17, valve 16 and pipe 15. The controlled amount of air mixed with the powder ensures that the powder passes efficiently through the diaphragm pump and out through the flexible pipe 7 to the hopper 8 avoiding compacting of the powder in the pump 6 and also ensuring that correct quantities of powder are fed into the hopper, or bag, 8.When a big bag is used a suitable vent filter is connected to the bag 8 to prevent a vacuum being created within the bag. It will of course be realised that in orderto provide a dust free powder handling system all joints between the various parts of the apparatus of the system are secure.

The hopper 8, as mentioned above, may be a big bag but it is conceivable that this hopper may be replaced by any transportable container of any size for transportation on a lorry for example. Alternatively the container may take the form of the hold of a ship. In the case of the hopper this may of course form the powder inlet to a particular process in which the powder is to be used.

Referring now to Figure 3 there is shown a modified form of the particulate transfer apparatus 3. In this embodiment the base 14 of the container is additionally provided with a fluidization plate 25 which in operation is effective to vibrate the powder within the apparatus 3 to prevent "bridging" of the powder within the apparatus. However, to ensure that the operation of the fluidization plate 25 does not interfere with the flow of powder through the outlet spout 4 and flexible pipe 5, a pinch valve 26 is connected to the end of the outlet spout 4. The pinch valve, of any conventional type, is so controlled as to close the outlet from the spout 4 prior to the operation of the fluidization plate 25. When the fluidization plate 25 is again inoperative the pinch valve is opened and the diaphragm pump again operates to suck powder from the fluid transfer apparatus 3.

One control system for controlling the operation of the fluidization plate 25 and the pinch valve 26 is shown in Figure 3. In this Figure, a control valve 30 is connected between a source 31 of compressed air at 50 p.s.i.g. and the pinch valve 26, valve 16, which in Figure 3 is shown as a pinch valve, and a valve 32 which, when open, allows compressed air from a compressed air source 33 to operate the fluidization plate 25. Both compressed air sources are fed from a single source 34 at 100 p.s.i.g.

Accordingly, when control valve 30 is operated, compressed air is fed simultaneously to both the pinch valves 16 and 26 which close and the fluidization plate valve 32 which is opened. Air at 5 p.s.i.g.

from source 33 is then applied to the fluidization plate 25 through valve 32 to enable the plate to fluidize the powder within the container of the fluid transfer apparatus 3. Conversely, actuation of valve 30 to stop the fluidization operation removes air from the pinch valves 16 and 26 which open, and from valve 32 which closes, shutting off the air supply to the fluidization plate 25.

For the sake of clarity the complete handling system is not shown in Figure 3 but it is to be assumed that such a system would be substantially identical to the apparatus disclosed in Figure 1, other than for the addition of the fluidizing plate 25.

The particulate transfer apparatus disclosed herein has been described as being of a tubular construction having a circular cross-section. However, the container body of the apparatus may take any convenient form and need not necessarily be of circular cross-section although such cross-section is preferable in order to ensure maximum transfer of a particular quantity of powder.

The outlet spout 4 is angled upwardly to prevent powder passing along the spout 4 and blocking the air inlet pipe 15, since when powder falls from the silo or big bag into the fluid transfer container it will not, as would a liquid, rise up the outlet spout.

Movement along the spout 4 is effected by the suction created by the diaphragm pump. The spout may be at other angles than that shown in the drawings, but should not be angled with its outer end downwardly.

The diaphragm pump disclosed herein is may be a WILDEN (trade name) pump and is air driven.

However, any diaphragm pump may be used and may be mechanically or electrically driven. Diaphragm pumps of different sizes, 2 inches or 3 inches inletioutlet have been used (5cm or 7.5cms) and the following performances have been obtained using such a diaphragm pump with the discharge apparatus of our invention to fill a 2m3 bag from a 125m3 silo: with a 2 inch pump - 700kg/ h of a powder of density of 200kg/m3 with a 3 inch pump - 2000kg/ h of density of 200kg/m3.

In an alternative form of a particulate transfer apparatus according to the invention the inlet pipe 15 is connected to a supply of gas, which may be any suitable gas depending upon the particular powder being transferred. However, in most cases and as described above the inlet pipe 15 is vented to the atmosphere.

Claims

1. A particulate transfer apparatus including a container having an open top, at least one side wall and a base, a particulate outlet spout located on the side wall of the container such that the longitudinal axis of the spout is horizontal or inclined with the free end of the spout upwardly, and a gas inlet located in the outlet spout such that in operation gas is mixed with the particulate and the mixture passes from the outlet spout.

2. An apparatus as claimed in claim 1, wherein the gas inlet pipe extends into the outlet spout by an amount at least equal to one and one quarter times the outside diameter of the outlet spout.

3. An apparatus as claimed in claim 1 or 2, wherein the base of the container is angled relative to said at least one side wall.

4. An apparatus as claimed in claim 3, wherein the inner face of the base faces the outlet spout.

5. An apparatus as claimed in claims 3 or 4, wherein the longitudinal axis of the spout is perpen dicularto the base.

6. An apparatus as claimed in any one of the preceding claims, wherein the gas inlet pipe extends from the outlet spout through and outwardly from the container.

7. An apparatus as claimed in claim 6, wherein the inlet pipe extends through the base.

8. An apparatus as claimed in any one of the preceding claims, wherein the end of the gas inlet pipe opposite to that located in the outlet spout is vented to the atmosphere.

9. An apparatus as claimed in any one of the preceding claims, wherein a gas control valve is connected to the gas inlet pipe.

10. An apparatus as claimed in claim 9, wherein the gas control valve is a needle valve.

11. An apparatus as claimed in any preceding claim, wherein a gas flowmeter is connected to the gas inlet pipe.

12. An apparatus as claimed in any one of the preceding claims, wherein a particulate transfer adaptor is connected to the top of the container.

13. An apparatus as claimed in claim 12, having an air vent in the adaptor.

14. An apparatus as claimed in any one of the preceding claims, wherein the container is tubular with a circular cross-section.

15. An apparatus as claimed in any one of the preceding claims, wherein the container is mounted on a frame.

16. An apparatus as claimed in claim 15, wherein the frame is mounted on rolling means.

17. An apparatus as claimed in any one of the preceding claims, including a diaphragm pump connected to the outlet spout.

18. An apparatus as claimed in claim 17, wherein the output of the diaphragm pump is connected to receiving means for receiving transferred particulate.

19. An apparatus as claimed in any one of the preceding claims, wherein the base of the container is provided with a fluidizing plate and a pinch valve is connected to the outlet spout, the pinch valve being controlled so that it is closed prior to the operation of the fluidizing plate.

20. A particulate transfer apparatus substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2 or Figure 3 of the accompanying drawings.

21. A process of transferring particulate, including feeding particulate into a container having an open top, at least one side wall and a base, removing particulate through an outlet spout located on the side wall of the container such that the longitudinal axis of the spout is horizontal or inclined with the free end of the spout upwardly, and simultaneously mixing gas from a gas inlet pipe in the outlet spout so that a mixture of gas and particulate are removed from the outlet spout.

22. A process as claimed in claim 21, wherein the flow of gas through the gas inlet is measured with a flowmeter and is controlled by adjusting a gas control valve to obtain the required gas flow reading on the flowmeter.

23. A process as claimed in claim 21 or 22, including venting the gas inlet pipe to the atmosphere.

24. A process as claimed in claim 21,22 or 23, including removing the mixture of particulate and gas from the container by a diaphragm pump.

25. A process as claimed in claim 24, including operating the diaphragm pump with compressed air.

26. A process as claimed in any one of claims 21 to 25, including fluidizing particulate in the container by a fluidizing plate located in the base of the container.

27. A process as claimed in claim 26, including closing a pinch valve connected to the outlet spout prior to operating the fluidizing plate to fluidize particulate within the container.

28. A process of transferring particulate substantially as hereinbefore described with reference to Figures 1 and 2 or Figure 3 of the accompanying drawings.