GB2352656A

GB2352656A - Particle separation assembly

Info

Publication number: GB2352656A
Application number: GB0017005A
Authority: GB
Inventors: Stewart Ives Ashworth; Terence Ives Ashworth
Original assignee: Vapormatt Ltd
Current assignee: Vapormatt Ltd
Priority date: 1999-07-12
Filing date: 2000-07-12
Publication date: 2001-02-07
Anticipated expiration: 2020-07-12
Also published as: GB9916246D0; GB2352656B; GB0017005D0

Abstract

A particle separation assembly 1 comprises a vessel 3, the vessel being provided with an inlet 4, a first outlet 5 at the lower end of the vessel and a second outlet 6 at the upper end of the vessel; the assembly being configured such that in use when a fluid carrying particles is pumped through the inlet 4 into the vessel and the flow rate of the fluid through the inlet is greater than the flow rate of fluid through the first outlet 5, the difference in flow rates giving rise to a resultant fluid flow which acts to convey a substantial proportion of particles below a predetermined mass to the second outlet. Thus, where the fluid carrying particles comprises particles of substantially the same density then those particles below the predetermined mass will generally be of a smaller size than those particles above the predetermined mass, and the smaller particles are conveyed upwards to the second outlet whereas the generally larger particles sink to the first outlet.

Description

2352656 PARTICLE SEPARATION ASSEMBLY The present invention relates to

particle separation assemblies. More particularly the invention relates to particle separation assemblies which employ a substantially non-centrifugal separation method.

According to a first aspect of the invention there is provided a particle separation assembly comprising a vessel, the vessel being provided with an inlet, a first outlet and a second outlet; the assembly being so arranged that in use when a fluid carrying particles is pumped through the inlet into the vessel and the flow rate of fluid through the inlet is greater than the flow rate of fluid through the first outlet, the difference in flow rates giving rise to a resultant fluid flow which acts to convey a substantial proportion of particles below a predetermined mass to the second outlet.

Thus where the fluid carrying particles comprises particles of substantially the same density then those particles below the predetermined mass will generally be of a smaller size than those particles above the predetermined mass, and the assembly therefore operates to separate particles by size.

Preferably the resultant fluid flow acts to convey a substantial proportion of those particles below the predetermined mass generally away from the first outlet.

Preferably those particles which are above the predetermined mass descend towards a specific region in the vessel.

Preferably those particles which are above the predetermined mass leave the vessel through the first outlet.

2 Preferably the first outlet is situated generally below the inlet.

Preferably the vessel is of tower form.

Preferably the first outlet is located towards the base of the vessel.

Preferably the inlet is located towards the base of the vessel.

Preferably the second outlet is located towards the top of the vessel.

According to a second aspect of the invention there is provided abrasive blasting apparatus which comprises a particle separation assembly in accordance with the first aspect of the invention.

According to a third aspect of the invention there is provided a method of separating particles comprising pumping a fluid carrying the particles through the inlet of a particle separation apparatus in accordance with the first aspect of the invention, and arranging that the flow rate of fluid through the inlet is greater than the flow rate of fluid through the first outlet.

Two embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a side elevation of a first embodiment of the invention, and Figure 2 shows a side elevation of a second embodiment of the invention.

3 Figure 1 shows a particle separation assembly 1 comprising a vessel 3. The vessel 3 is provided with an inlet 4, a first outlet 5 and a second outlet 6. The inlet 4 and the first outlet 5 are both valved.

The vessel 3 is of tower-like form with generally cylindrical shape comprising a lowermost portion 7 which is funnel shaped. The first outlet is located on the lowermost portion 7 of the vessel 3. The inlet 4 and the second outlet 6 are situated on the top of the vessel 3.

The assembly 1 further comprises an inlet conduit 8 which is provided inside the vessel 3 and is of cylindrical shape. The uppermost end of the inlet conduit 8 is attached to the inlet 4, from where said inlet conduit extends part way down inside and substantially coaxial to the vessel 3.

In use the assembly operates as follows. A fluid carrying particles having a range of sizes is pumped through the inlet 4 and into the inlet conduit 8.

The conduit 8 is sized so as to reduce the flow speed inside the conduit 8 relative to the flow speed at which the fluid is pumped into the conduit 8 through the inlet 4. This reduction in flow speed results in the avoidance of excessive turbulence inside the vessel 3.

All the particles entering the vessel 3 are of substantially the same density. The inlet conduit 8 is provided with a plurality of apertures which are situated towards the lowermost end of the inlet conduit 8 and which act to diffuse the flow of fluid leaving said inlet conduit. The valve on the first outlet 5 is adjusted so that the rate at which fluid entering the vessel via inlet conduit 8 is greater than the rate at which fluid may leave the vessel 3 via the first outlet 5. The difference in the flow rate (measured as volume per unit time) between the inlet conduit 8 4 and the first outlet 5 gives rise to a resultant fluid flow which acts to fill the annular shaped space around the inlet conduit 8. The speed of this resultant upward fluid flow will be sufficient to convey only a proportion of the particles entering the vessel up towards the second outlet 6, ie those particles below a certain predetermined mass. Given that the particles entering the vessel are of substantially the same density then the size of particle is directly proportional to the mass of particle and thus the velocity of the upward flow will be sufficient to carry only those particles below a certain size. Hence a substantial proportion of the smaller particles (fines) are conveyed to the second outlet 6 and the heavier larger particles (abrasives) and a proportion of fines descend towards the first outlet 5.

The maximum size of particle which can be conveyed to the second outlet 6 can be determined by adjusting the speed of the resultant fluid flow.

This is achieved by varying the degree to which the first outlet 5 is open. A speed sensor comprising two transducers 12 and 13 allows the speed of the resultant fluid flow to be monitored.

The position of the lowermost end of the inlet conduit 8 is positioned relative to the lowermost section of the vessel 3 to given optimum particle distribution.

The particle separation assembly 1 is of particular use in the field of abrasive blasting such as vapour blasting. The particles used are typically glass beads or aluminium oxide. Advantageously the inventive particle separation assembly 1 allows those particles which are large enough to produce sufficient abrasive effect to be re-used by separating those abrasive particles from particulate matter collected (typically by a sump) during the blasting process.

In a modification of the particle separation assembly 1 the inlet 4 and outlet 5 are not valved (and thus unadjustable) but instead are of a fixed size.

Figure 2 shows a particle separation assembly 2 in which like components have been given corresponding reference numerals. The assembly 2 operates fundamentally in the same manner as the assembly 1. However, in the assembly 2 the inlet conduit 8 and the inlet 4 have been replaced by an inlet 15. The inlet 15 is located on the lower half of the vessel 3.

In an alternative embodiment (not illustrated) the space through which the resultant fluid flow is conveyed comprises a plurality of conduits of relatively small cross-sectional area. The conduits extend k6nerally upwardly and towards a region which is adjacent to -the second outlet. Advantageously a particle separation assembly comprising a plurality of such conduits improves the streamlining of the resultant fluid flow and thus the vessel of the modified assembly comprising the plurality of conduits can be shorter in height than the assembly of Figure 1, where the total cross-sectional area of the conduits is substantially equal to the cross-sectional area of the annular shaped space around the inlet conduit 8. Alternatively suitable baffling means could be used to effectively provide a plurality of relatively small cross-sectional area conduits to the second outlet.

6

Claims

1. A particle separation assembly comprising a vessel, the vessel being provided with an inlet, a first outlet and a second outlet; the assembly being so arranged that in use when a fluid carrying particles is pumped through the inlet into the vessel and the flow rate of fluid through the inlet is greater than the flow rate of fluid through the first outlet, the difference in flow rates giving rise to a resultant fluid flow which acts to convey a substantial proportion of particles below a predetermined mass to the second outlet.

2. A particle separation assembly as claimed in claim 1 in which the resultant fluid flow acts to convey a substantial proportion of those particles below the predetermined mass generally away from the first outlet.

3. A particle separation assembly as claimed in claim 1 or claim 2 in which those particles which are above the predetermined mass descend towards a specific region in the vessel.

4. A particle separation assembly as claimed in any preceding claim in which those particles which are above the predetermined mass leave the vessel through the first outlet.

5. A particle separation assembly as claimed in any preceding claim in which the first outlet is situated generally below the inlet.

6. A particle separation assembly as claimed in any preceding claim in which the vessel is of tower form.

7 7. A particle separation assembly as claimed in any preceding claim in which the first outlet is located towards the base of the vessel.

8. A particle separation assembly as claimed in any preceding claim in which the inlet is located towards the base of the vessel.

9. A particle separation assembly as claimed in any preceding claim in which the second outlet is located towards the top of the vessel.

10. A particle separation apparatus substantially as described with reference to Figure 1 of the accompanying drawings.

11. A particle separation apparatus substantially as described with reference to Figure 2 of the accompanying drawings.

12. Abrasive blasting apparatus which comprises a particle separation apparatus as claimed in any of claims 1 to 11.

13. A method of separating particles comprising pumping a fluid carrying the particles through the inlet of a particle separation apparatus in accordance with any one of claims 1 to 9, and arranging that the flow rate of fluid through the inlet is greater than the flow rate of fluid through the first outlet.

14. A method of separating particles substantially as described herein with reference to the accompanying drawings.