GB2412890A

GB2412890A - Slurry feed system

Info

Publication number: GB2412890A
Application number: GB0505149A
Authority: GB
Inventors: Stewart Ives Ashworth
Original assignee: Vapormatt Ltd
Current assignee: Vapormatt Ltd
Priority date: 2004-03-16
Filing date: 2005-03-14
Publication date: 2005-10-12
Anticipated expiration: 2025-03-14
Also published as: GB2412890B; GB0505149D0; GB0405854D0

Abstract

A slurry feed system 7 for a wet blast throwing wheel assembly 1, the feed system 7 comprising a tubular separator (29 fig.4) having an abrasive slurry inlet (58, fig.4), an abrasive slurry outlet (50, fig 4) and a liquid outlet (57, fig.4) the arrangement of the slurry feed system 7 being such that an abrasive-liquid slurry pumped through the abrasive slurry inlet (58 fig.4) spins along the separator (29, fig.4) such that the abrasive at least partially separates from the liquid by moving radially outwardly of the axis of the separator (29, fig.4), the separated abrasive being ejected via the abrasive slurry outlet (50, fig.4) to feed the throwing wheel 5, and the non-separated liquid-abrasive slurry being ejected via the liquid outlet (57, fig.4). The abrasive slurry outlet (50, fig.4) may be an elongate slot in the wall of the separator (29, fig.4), and a conical region (42, fig.6) may be provided within the tubular separator. A wet blast throwing wheel assembly 1 including such a feed system 7 is also provided.

Description

24 1 2890

SLURRY FEED SYSTEM

The present invention relates to a slurry feed system and particularly to a slurry feed system for supplying an abrasive-liquid slurry to a wet blast throwing wheel.

It has previously been proposed to provide a wet blast slurry wheel comprising a central hub and a plurality of blades extending radially outwardly from the hub. A slurry comprising abrasive particles in suspension in a liquid is pumped onto the blades and, as the wheel spins, the slurry is flung from the blades and onto an article to be cleaned or degreased. Such an article could be a vehicle such as a car or train, or may comprise strip metal or fabricated parts.

The liquid can be pumped onto the blades using a right-angled nozzle which directs the slurry into the hub of the wheel and then radially outwardly of the hub and onto the blades in a direction parallel to the blades. It is desirable to dewater the slurry so that the volume of water being flung from the wheel is minimised and so that the abrasive-to-water concentration of the slurry increases. It has previously been shown that mounting the right angled nozzle at or close to the wheel hub gives a good abrasive-to-water concentration.

However the use of a right angled nozzle creates a non uniform jet of slurry onto the wheel blades. We believe this is because the centrifugal force acting on the slurry forces the heavier particles in the slurry to the outside of the bend of the nozzle. In addition, the right-angled nozzle still suffers from flinging an undesirably high volume of water from the wheel.

According to a first aspect of the invention there is provided a slurry feed system for a wet blast throwing wheel assembly, the feed system comprising a tubular separator having an abrasive slurry inlet, an abrasive slurry outlet and a liquid outlet, the arrangement of the slurry feed system being such that an abrasive-liquid slurry pumped through the abrasive slurry inlet spins along the separator such that the abrasive at least partially separates from the liquid by moving radially outwardly of the axis of the separator, the separated abrasive being ejected via the abrasive slurry outlet to feed the throwing wheel, and the non-separated 1iquid-abrasive slurry being ejected via the liquid outlet.

Preferably the abrasive slurry outlet is radially spaced from the axis of the separator.

Preferably the abrasive slurry outlet comprises an elongate slot in the wall of the separator the axis of which is parallel with the axis of the tubular separator.

Preferably the length of the elongate slot is substantially identical to the depth of the throwing wheel, the depth being measured in a direction parallel to the axis of rotation of the slurry wheel.

Preferably the abrasive slurry outlet is distal from the abrasive slurry inlet.

Preferably the tubular separator comprises a conical region which tapers inwardly in a direction away from the abrasive slurry inlet.

Preferably the conical region tapers inwardly to a tubular region, the abrasive-slurry outlet being formed in the tubular region.

As the abrasive-liquid slurry passes through the abrasive slurry inlet and into the conical region, the abrasive slurry spins about the axis of the separator as the slurry moves towards the abrasive slurry outlet, the spinning causing centrifugal forces to act on the abrasive slurry such that the heavier abrasive particles in the slurry move radially outwardly to the inner walls of the separator and the lighter liquid particles remain adjacent the axis of the separator.

Preferably the diameter of the tubular region is substantially uniform.

Preferably the end of the tubular region distal from the abrasive slurry inlet is closed. Most preferably the closed end of the tubular region comprises an inwardly directed cone which extends into the tubular region.

Preferably the abrasive slurry inlet is positioned adjacent the mouth of the conical region. Preferably the abrasive slurry inlet comprises a tube, the axis of which is perpendicular to the axis of the tubular separator.

Preferably the liquid outlet comprises a tubular region, the axis of which is parallel to the axis of the tubular separator.

Preferably one end of the tubular region is adjacent the mouth of the conical region of the separator.

Preferably the liquid outlet is arranged in the separator so as not to be in direct communication with the abrasive slurry inlet.

Preferably the separator comprises two components which are secured together. Preferably one component is formed with the conical region and the abrasive outlet and the other component is formed with the abrasive slurry inlet and the liquid outlet.

Preferably one of the components comprises a circumferential boss against which the other component abuts when the separator is fully assembled.

Preferably the boss comprises mounting means to mount the separator on a throwing wheel assembly.

According to a second aspect of the invention there is provided a wet blast throwing wheel assembly comprising a wet blast throwing wheel and the slurry feed system of the first aspect of the invention, the arrangement of the assembly being such that the slurry feed system feeds abrasive slurry to the wet blast throwing wheel.

Preferably the throwing wheel assembly comprises a housing, the throwing wheel being mounted for rotation within the housing, part of the slurry feed system extending into the hub of the wheel assembly through the housing.

Preferably the wheel assembly comprises pump means to pump the abrasive slurry into the slurry feed system.

Preferably the outlet of the slurry feed system is positioned adjacent the hub of the throwing wheel.

Preferably the conical region of the slurry feed system is adjacent the hub of the throwing wheel.

Alternatively the conical region of the slurry feed system is remote from the hub of the throwing wheel assembly.

Preferably the throwing wheel comprises a disc mounted for rotation on the housing, and at least one blade mounted on the disc.

Preferably the throwing wheel comprises a plurality of blades.

Preferably the plane of the or each blade is angled away from the plane of the disc. Most preferably the plane of the or each blade is substantially perpendicular to the plane of the disc.

Preferably the or each blade can be removed from the disc so as to be replaced or repaired.

Preferably the part of the separator formed with the abrasive slurry outlet extends through the disc so that the abrasive slurry outlet is located adjacent the inner end of the or each blade.

Other aspects of the present invention may include any combination of the features or limitations referred to herein.

The present invention may be carried into practice in various ways, but embodiments will now be described by way of example only with reference to the accompanying drawings in which: Figure l is an end view of a throwing wheel assembly in accordance with the present invention; Figure 2 is a section side view taken along line A-A of Figure 1; Figure 3 is an exploded perspective view of a throwing wheel forming part of the assembly of Figures 1 and 2; Figure 4 is a perspective view of a slurry feed assembly in accordance with the present invention; Figure 5 is an end view of the slurry feed assembly of Figure 4; Figure 6 is a sectional view along line A-A of Figure 5; and Figure 7 is also a sectional view along line A-A of Figure 5 but shows the slurry feed system in use.

Referring initially to Figures I and 2, a wet blast throwing wheel assembly 1 comprises a rectangular housing 3 in which a throwing wheel 5 and a slurry wheel feed system 7 are mounted.

The housing 3 is substantially cuboid and houses a semi-cylindrical container 9 (shown in phantom) having a rectangular opening 11 which opens into one side of the housing 3.

Referring to Figure 3, the wet blast throwing wheel 5 comprises a disc 13 having six blades 15 removably mounted thereon. The blades 15 are mounted in equispaced relationship and each blade 15 extends radially away from the central hub 17 of the wheel 5. The plane of each blade 15 is substantially perpendicular to the plane of the disc 13. The end of each blade 15 closest to the hub 17 is nonetheless spaced a small distance from the axis of the hub 17.

Each blade 15 comprises a rectangular backing plate 19 formed with a centrally located square aperture 21. One of the longer edges of the backing plate 19 is formed with two spaced apart lugs 23 which are received in corresponding elongate apertures 24 formed in the disc 13 of the wheel 5. Each lug 23 extends in a direction parallel to the plane of the backing plate 19. Each lug 23 is provided with two spaced apart locating pins 25, 26 which are perpendicular to the plane of the backing plate 19. The pins 25, 26 are spaced apart by a distance equal to the thickness of the disc 13. A channelled element 27 formed with a rectangular base 28 and upstanding side walls 29 is mounted on the backing plate l9. Thus each blade 15 comprises a channel.

The blades 15 are mounted on the disc 13 by inserting the lugs 23 of each blade 15 through a respective elongate aperture 24 slot formed in the disc 13. One pin 25 is located on one side of the disc 13 and the other pin 26 is located on the other side of the disc 13. The blade 15 can then be slid radially outwardly along the disc 13 so that part of the disc 13 is sandwiched between each pair of pins 25, 26. This ensures that the blades 15 are securely mounted on the disc 13 but can still be removed for repair or replacement when desired. When the disc 13 rotates, the centrifugal force acting on each blade 15 acts to force each blade 15 further radially outwardly so ensuring that each blade 15 remains secured to the disc 13 in use.

With the blades 15 secured to the disc 13, the assembled wheel 5 is mounted for rotation within the semi cylindrical container 9. The wheel 5 is mounted using any known means such as, for example, rotational bearings. The wheel 5 is connected to a drive shaft of a motor 27 which may be, for example, an electric motor. In use the motor 27 rotates the wheel within the semi cylindrical container 9. The wheel 5 may be rotated at up to 4000rpm. The wheel 5 may alternatively comprise two spaced apart discs having blades 15 sandwiched there between. Indeed the wheel 5 shown in Figure 5 does comprise two discs.

Referring now to Figures 4 to 7, the slurry feed system 7 comprises a tubular separator 29 assembled from two interengaging parts 30, 32. The first part 30 comprises a tube 34 formed with an axially extending bore. 36 of constant diameter. One end 38 of the bore 36 is closed. The other end 40 of the bore 36 leads to a conical region 42 which flares radially outwardly from the bore 36 to a mouth 44, the diameter of the mouth 44 being greater than the diameter of the bore 36. The exterior of the first part 30 is formed with a circumferential boss 46 which is located between the mouth 44 and the end 38. The closed end of the bore 36 is formed with a shallow cone 48 which extends into the bore 36. An abrasive slurry outlet is provided by an elongate slot 50 formed in the wall of the tube. 34, the axis of the slot 50 being parallel with the axis of the tube 34.

The other part 32 of the slurry feed system 7, comprises a hollow cylinder 52 one end 54 of which is substantially closed and the other end 56 of which is substantially open. An outlet pipe 57 extends through the closed end 54 so as to protrude from the inner and outer face of the closed end 54. The axis of the liquid outlet pipe 56 is aligned with the axis of the cylinder 52.

An abrasive slurry inlet pipe 58 extends into the cylinder 52 adjacent closed end 54, the axis of the inlet pipe 58 being substantially perpendicular to the axis of the cylinder 52. The axis of the inlet pipe 58 is spaced from the axis of the liquid outlet pipe 56 with part of the exterior of the inlet pipe 58 resting on the exterior of the outlet pipe 56.

Thus the outlet pipe 56 and the inlet pipe 58 are not in direct communication.

The open end 56 of the cylinder 52 is dimensioned to receive one end of tube 34 of the first part.30 so that the boss 46 abuts the open end 56 of the cylinder 52. The mouth 44 of the conical region is adjacent the liquid outlet pipe 56 so as to be axially aligned therewith, and is also adjacent the inlet pipe 58 so as to be substantially perpendicular thereto.

The tube 34 of the assembled separator 29 is then received though a circular aperture formed in a side wall of the semi-cylindrical container 9. The boss 46 abuts the wall so as to prevent further movement of the separator 29 into the container 9. The end of the tube 34 is received into the hub 17 of the throwing wheel 5 so that the elongate slot 50 is located within the hub 17. The length of the slot 50 is substantially identical to the width of each blade 15 and it will be appreciated that, as the wheel 5 rotates, each blade 15 will rotate to a position in which the outlet slot 50 opens onto the blade 15.

The abrasive slurry inlet 58 is connected to a reservoir of slurry, the slurry comprising abrasive particles in suspension in a suitable liquid which may be, for example, water. A pump (not shown) is provided to pump the slurry from the reservoir to the inlet 58. The liquid outlet 56 may also be connected to the slurry reservoir or may alternatively be connected to a separate reservoir.

In use, abrasive slurry is pumped through the inlet 58 and into the separator 29. The slurry flows around the interior of the hollow cylinder 52 and thus spins around the axis of the separator 29. As more slurry is pumped into the separator 29 the spinning slurry moves axially along the separator 29 and passes into the mouth 44 of conical region 42.

The effect of the decreasing radius conical portion 42 is to increase the speed at which the slurry spins through the separator 29.

When the spinning slurry reaches the constant diameter bore 36, the slurry is spinning sufficiently quickly for significant centrifugal forces to act on the slurry and in particular on the heavier components of the slurry which, in this case, are the abrasive particles. The abrasive particles are thus flung radially outwardly to the outer walls of the bore 36 and continue spinning around these walls. The liquid, being lighter than the abrasive particles, is not flung radially outwardly to such an extent. Thus some of the liquid is separated from the abrasive and remains located in the centre of the bore 36 adjacent the axis of the bore 36. As more liquid collects in this region, the liquid flows towards and through the liquid outlet 56 and into the slurry reservoir or the separate reservoir. This flow of liquid from the separator occurs in a generally opposite direction to the direction of flow of the abrasive slurry. This is shown in Figure 7. The liquid may still have some abrasive particles suspended therein.

The remaining abrasive slurry which is spinning around the walls of the bore 36 eventually reaches the outlet slot 50. The abrasive slurry flows through the slot 50 and onto the blades 15 of the rotating wheel 5.

Rotation of the wheel 5 exerts a centrifugal force on the abrasive slurry which moves along the blades 15 away from the hub 17. When the abrasive slurry reaches the end of the blades 15, the abrasive slurry is flung from the wheel 5, through the opening 11 in the semi cylindrical container 9 and onto the article to be cleaned.

It will be appreciated that the combination of the speed of rotation of the abrasive slurry in the bore 36 and the size of the outlet slot 50 is such that the abrasive slurry forms a high pressure jet flow from the slot 50.

The jet is substantially uniform along the length of the slot 50 and thus an equal volume of slurry is deposited across the width of the blades 15.

This ensures that the blades 15 wear more regularly across their width and ensures that a more equal volume of slurry is flung across the width of the blades 15.

Further to this the abrasive slurry being flung from the blades 15 has a relatively high abrasive to liquid ratio because some of the liquid has been separated from the abrasive slurry so to flow out of the separator 29 through the liquid outlet 56. This has the beneficial effect of reducing the volume of liquid flung from the wheel 5, whilst increasing the volume of abrasive being flung from the wheel 5.

Claims

1. A slurry feed system for a wet blast throwing wheel assembly, the feed system comprising a tubular separator having an abrasive slurry inlet, an abrasive slurry outlet and a liquid outlet, the arrangement of the slurry feed system being such that an abrasive-liquid slurry pumped through the abrasive slurry inlet spins along the separator such that the abrasive at least partially separates from the liquid by moving radially outwardly of the axis of the separator, the separated abrasive being ejected via the abrasive slurry outlet to feed the throwing wheel, and the non-separated liquid-abrasive slurry being ejected via the liquid outlet.

2. The slurry feed system of claim I wherein the abrasive slurry outlet is radially spaced from the axis of the separator.

3. The slurry feed system of claim 2 wherein the abrasive slurry outlet comprises an elongate slot in the wall of the separator the axis of which is parallel with the axis of the tubular separator.

4. The slurry feed system of claim 3 wherein the length of the elongate slot is substantially identical to the depth of the throwing wheel, the depth being measured in a direction parallel to the axis of rotation of the slurry wheel.

5. The slurry feed system of any one of the preceding claims wherein the abrasive slurry outlet is distal from the abrasive slurry inlet.

6. The slurry feed system of any one of claims 2 to 5 wherein the tubular separator comprises a conical region which tapers inwardly in a direction away from the abrasive slurry inlet.

7. The slurry feed system of claim 6 wherein the conical region tapers inwardly to a tubular region, the abrasive-slurry outlet being formed in the tubular region.

8. The slurry feed system of any one of the preceding claims wherein, in use, as the abrasive-liquid slurry passes through the abrasive slurry inlet and into the conical region, the abrasive slurry spins about the axis of the separator as the slurry moves towards the abrasive slurry outlet, the spinning causing centrifugal forces to act on the abrasive slurry such that the heavier abrasive particles in the slurry move radially outwardly to the inner walls of the separator and the lighter liquid particles remain adjacent the axis of the separator.

9. The slurry feed system of claim 7 or claim 8 wherein the diameter of the tubular region is substantially uniform.

lO. The slurry feed system of any one of claims 7 to 9 wherein the end of the tubular region distal from the abrasive slurry inlet is closed.

ll. The slurry feed system of claim 10 wherein the closed end of the tubular region comprises an inwardly directed cone which extends into the tubular region.

12. The slurry feed system of any one of claims 6 to 11 wherein the abrasive slurry inlet is positioned adjacent the mouth of the conical region.

13. The slurry feed system of any one of the preceding claims wherein the abrasive slurry inlet comprises a tube, the axis of which is perpendicular to the axis of the tubular separator.

l4. The slurry feed system of any one of the preceding claims wherein the liquid outlet comprises a tubular region, the axis of which is parallel to the axis of the tubular separator.

15. The slurry feed system of claim 14 wherein one end of the tubular region of the liquid outlet is adjacent the mouth of the conical region of the tubular separator.

16. The slurry feed system of claim 14 or claim 15 wherein the liquid outlet is arranged in the separator so as not to be in direct communication with the abrasive slurry inlet.

17. The slurry feed system of any one of claims 6 to 16 wherein the separator comprises two components which are secured together.

18. The slurry feed system of claim 17 wherein one component is formed with the conical region and the abrasive outlet and the other component is formed with the abrasive slurry inlet and the liquid outlet.

19. The slurry feed system of claim 17 or claim 18 wherein one of the components comprises a circumferential boss against which the other component abuts when the separator is fully assembled.

20. The slurry feed system of claim 19 wherein the boss comprises mounting means to mount the separator on a throwing wheel assembly.

21. A wet blast throwing wheel assembly comprising a wet blast throwing wheel and the slurry feed system of claims 1 to 20, the arrangement of the assembly being such that the slurry feed system feeds abrasive slurry to the wet blast throwing wheel.

22. The wet blast throwing wheel assembly of claim 21 comprising a housing, the throwing wheel being mounted for rotation within the housing, part of the slurry feed system extending into the hub of the wheel assembly through the housing.

23. The wet blast throwing wheel assembly of claim 21 or claim 22 comprising pump means to pump the abrasive slurry into the slurry feed system.

24. The wet blast throwing wheel assembly of any one of claims 21 to 23 wherein the outlet of the slurry feed system is positioned adjacent the hub of the throwing wheel.

25. The wet blast throwing wheel assembly of claim 24 wherein a conical region of the slurry feed system is adjacent the hub of the throwing wheel.

26. The wet blast throwing wheel assembly of claim 24 wherein a conical region of the slurry feed system is remote from the hub of the throwing wheel assembly.

27. The wet blast throwing wheel assembly of any one of claims 21 to 26 wherein the throwing wheel comprises a disc mounted for rotation on the housing, and at least one blade mounted on the disc.

28. The wet blast throwing wheel assembly of claim 27 wherein the throwing wheel comprises a plurality of blades.

29. The wet blast throwing wheel assembly of claim 27 or claim 28 wherein the plane of the or each blade is angled away from the plane of the disc.

30. The wet blast throwing wheel assembly of claim 29 wherein the plane of the or each blade is substantially perpendicular to the plane of the disc.

31. The wet blast throwing wheel assembly of any one of claims 27 to 30 wherein the or each blade can be removed from the disc so as to be replaced or repaired.

32. The wet blast throwing wheel assembly of any one of claims 27 to 31 wherein the part of the separator formed with the abrasive slurry outlet extends through the disc so that the abrasive slurry outlet is located adjacent the inner end of the or each blade.

33. A slurry feed system substantially as described herein with reference to the accompanying drawings.

34. A wet blast throwing wheel assembly substantially as described herein with reference to the accompanying drawings.