Current methods, such as the use of filtration, settlement channels and lagons, for particulate separation from fluids suffer from a number of difficulties such as: a) changes in the relative specific gravity between the particulates and the fluid; b) changes in the specific gravity of the fluid; c) changes in the viscosity of the fluid; d) changes in the average particle sizes or in their size distribution; e) changes in the nature of the particulates or the fluid or both such that the effectiveness of the coagulant (s) and floculent (s) that may be in use are affected; hydrodynamic issues within the system, within the feed or within the exit arrangements which conflit with the performance of any coagulants or flocculents on contaminants to form coagulated or flocculated groupings; g) simple flow surges or variability in the concentration of particulates that are present in the feed mixture; h) temperature, wind and other induced eddy, circulatory or stratificationproblems; i) comparatively large site area requirements.

The above difficulties are particularly acute when the particulates have a very small relative specific gravity with respect to the fluid, the particle sizes are small, or the relative specific gravity varies through zero.

The latter situation can typically occur with three phase mixtures such as oil-water-solid, oil-water-gas or solid-water-gas due to the properties of three phase mixtures.

According to a first aspect of the present invention there is provided a method for the separation of particulates from a fluid, said method comprising the steps of: i) introducing the fluid containing particulates into a substantially closed separator; ii) imparting a motion to the fluid in an agglomeration chamber within the separator in such a way as to cause agglomeration of particulates in the fluid by bringing them into close mutual proximity or mutual contact; and iii) effecting relative gravimetric settling of the fluid and the agglomerated particles.

Preferably, step ii) is effected by causing the fluid to move with two mutually transverse (preferably mutually perpendicular) components of flow direction.

Preferably, each component of flow direction is a substantially helical direction.

Preferably also, the method further includes the step of causing a portion of the fluid which has left the agglomeration chamber to enter a separation chamber within the separator. Preferably said motion imparted to the fluid in the agglomeration chamber is inhibited before the fluid enters the separation chamber.

Preferably, the method also includes the step of causing a further portion of the fluid to enter a further separation chamber within the separator.

Preferably, the method also includes the step of causing a further portion of the fluid to pass through at least one tube communicating with at least one other separation chamber within the separator.

Preferably, said agglomeration chamber is annular and its cross-sectional shape may be substantially circular, substantially elliptical or even polygonal. Preferably the method includes the step of the fluid passing transversely inward, or outward of said agglomeration chamber prior to entering said separation chamber or chambers.

Preferably, the method includes the step of decanting the substantially clean fluid from the or each separation chamber into a receiving region.

Preferably, the bulk rate of flow of the particulate containing fluid into the separator is less than the combined separation rate of the fluid and agglomerated particulates within the separator. In at least one, and preferably all of the agglomeration and separation chambers, the vertical flow rate of fluid therein is preferably of sufficiently low volume as to create a zone for particulate build-up that allows fluid to flow through a self-replenishing bed of already agglomerated particles to further filter the fluid travelling through and thereby continue the agglomeration process.

This results in the production of a gently moving fluid-supported bed where the agglomeration process continues. This bed enables very efficient removal of any remaining fine particulates.

In a particularly preferred embodiment, within the agglomeration chamber there is a substantially continuous zone or bed of continuously moving and agglomerating particles supported by the moving fluid and contained by boundary walls of the chamber. A particularly preferred feature of the present invention is the creation of a flow regime within the agglomeration chamber which develops this bed or zone of particles, which enables the larger agglomerated particles and any other larger particles within the feed to the separator to move on into the separation chamber (s), and which enables the fluid within the agglomerating chamber to continually enter and leave this bed of agglomerating solids, thereby creating maximum opportunity for the fine particles within the fluid to become associated with the agglomerates. As a result of this continuous entering and leaving process, the fluid leaving the subsequent separation chamber (s) has a much lower concentration of fine suspended particulates than can normally be achieved using coagulation and flocculation techniques in conjunction with gravity separation.

The method of the present invention does not rely on centrifugal forces to enhance specific gravity differences between the fluid and the particulates.

The method of the present invention may be used in conjunction with known agglomerating or flocculating techniques to promote or enhance agglomeration of the particulates. These flocculating techniques include the use of chemical flocculating agents, coagulating agents, dielectric field strength or ionic strength variations. The method of the present invention may be preceded by a pre-treatment or pre-dosing of the fluid to precipitate or coagulate and/or flocculate dissolve matter. Alternatively or additionally, treatment may take place in the agglomeration chamber.

The quality of mixing and the homogenising effects that are created as a result of the present invention within the fluid within the agglomeration chamber are such that in many instances there is no need for pre-mixing and pre-reacting vessels and other associated equipment, pumps, agitators, pipework and controls. It therefore follows that a key benefit of this present invention is reduction in cost, complexity and space requirements for the necessary chemical processing, dosing and resultant separation equipment that would normally be required for precipitating and removing particulates from fluids containing unwanted components or particulates.

The particulates may be solid, and/or semi-solid, and/or liquid.

According to a further aspect of the present invention there is provided separation apparatus for separating particulates from a fluid comprising an agglomeration chamber; inlet means for introducing fluid containing particulates to be separated into the agglomeration chamber; means for imparting a motion to the fluid in the agglomeration chamber in such a way as to cause agglomeration of particulates in the fluid by bringing them into close mutual proximity or mutual contact; and a separation chamber in which, in use, said agglomerated particulates are gravimetrically separated from the fluid.

Preferably, said agglomeration chamber is annular and its cross-sectional shape may be substantially circular, substantially elliptical or even polygonal. More preferably said agglomeration chamber has a depth which is at least twice its width. This enhances the opportunity for the particulates to come into close proximity or contact with one another and thereby agglomerate.

Desirably said separation apparatus is provided with a lid. More desirably said separation apparatus is provided with thermal shielding. These measures serve to mitigate the risk of wind and temperature induced eddy, circulatory or stratification problems.

Advantageously at least two separation chambers are nested within said separation apparatus. The chambers preferably include regions which are downwardly convergent, e. g. downwardly convergent conical regions.

The separation chambers may be disposed inwardly and/or outwardly of the agglomeration chamber. These measures provide a particularly compact arrangement. By arranging the separation chambers to be at different levels within the apparatus, it is possible to obtain an effective total cross-sectional area for separation which exceeds the cross-sectional area of the apparatus itself. Indeed, it is considered possible to make the apparatus so compact that it can be transported by road, rail, sea, river or canal to the site of intended use. It is considered possible to reduce installation, testing and commissioning costs by providing the apparatus as a packaged, factory manufactured product. The apparatus may take the form of a self-contained vehicular or trailer mounted apparatus having all ancillary pumps and plant attached thereto.

The invention will now be described, by way of non-limiting examples only, with reference to the following drawings in which: Figure 1 is a schematic representation of the arrangement of the major internal features of a separator according to the present invention.

Figure 2 is a cross-sectional view through the separator of Figure 1 along the I ine A-A.

Figure 3 is a cross-section through the separator of Figure 1 along the line B-B.

Figure 4 is a cross-section through the separator of Figure 1 along the line C-C.

Figure 5 is a cross-section through the separator of Figure 1 along the line D-D.

Figure 6 is a cross-section through the separator of Figure 1 along the line E-E.

Figure 7 is a cross-section through the separator of Figure 1 along the line F-F.

Figure 8 is a detailed view of a first modification of the separator of Figure 1.

Figure 9 is a detailed view of a second modification of the separator of Figure 1.

Figure 10 is a schematic partial representation of the arrangement of the major internal features of a separator according to a second embodiment of the present invention.

Figure 11 is a schematic representation of the arrangement of the major internal features of a separator according to a third embodiment of the present invention.

Figure 12 is a schematic representation of the arrangement of the major internal features of a separator according to a fourth embodiment of the present invention.

Referring to the drawings the separator in this embodiment is designed to separate solid, and/or semi-solid, and/or liquid contaminant particles from a fluid. In the embodiment described hereinafter, the fluid is a liquid having a density lower than the particles. The separator includes an outer vessel 10 which has an upper plain cylindrical wall12 and a lower downwardly convergent frusto-conical wall 13. Internally of the cylindrical wall 12 there is provided a downwardly convergent, frusto- conical skirt 14 which is concentric with the wall sections 12 and 13 and whose upper end is completely sealed with the inner surface of the cylindrical wall 12 intermediate the upper and lower ends thereof.

An inner vessel 15 having an upper plain cylindrical wall 16 and a short, lower, downwardly convergent, frusto-conical skirt 17 is secured concentrically within the outer vessel 10. The top of the skirt 17 is disposed a short distance below the top of the skirt 14 and extends downwardly for about a quarter of the length of the latter. The outer surface of the cylindrical wall 16 of the inner vessel 15 and the inner surface of the cylindrical wall 12 of the vessel 10 define an annular flow passage 18 therebetween. Similarly the frusto-conical skirts 14 and 17 define a continuation of said flow passage 18. The flow passage 18 is closed at its upper end by a top wall 19. An inlet nozzle 20 of fixed size opens tangentially into the annular flow passage 18 adjacent the top wall 19. Alternatively the nozzle 20 can be of variable size.

A funnel shaped vessel 21 having a downwardly convergent frusto-conical wall 21 a and a short, plain cylindrical wall 21 b is secured concentrically within the vessel 15. The upper end of the funnel shaped vessel 21 is completely sealed with the inner surface of the cylindrical wall 16 at a level slightly below that of the top wall 19. The wall 21b projects downwardly to terminate just above the lower edge of the skirt 17.

Extending between the inner surface of the inner vessel 15 and the outer surface of the vessel 21 are a series of four equi-angularly spaced, radially extending plate-like baffles 22. Each baffle 22 is vertically arranged and projects below the skirt 17 and the wall 21 b to approximately the level of the lower edge of the skirt 14. The upper edge of each baffle 22 is horizontal and is spaced some way above the junction between the walls 21a and 21 b. The baffles are disposed partly within a separation chamber 23 defined between the inner surface of the inner vessel 15 and the upper part of the outer surface of said funnel shaped vessel 21.

Four open ended vertical pipes 24 pass upwardly from the chamber 23 through the wall 21 a of the funnel shaped vessel 21 to extend into a second separation chamber 25. The second chamber 25 is defined by the inner surfaces of the upper part of the cylindrical wall 16 of the inner vessel 15, the second frusto-conical wall 21a and the plain cylindrical wall 21b. The outer surfaces of the pipes 24 are sealed with the wall 21a. In this embodiment, the pipes 24 have a square section 26, a pyramidal section 27 and a narrow cylindrical section 28. The lower end of the square section 26 is at a level between the lower edges of the skirts 14 and 17.

The pipes 24 have parallelogram-shaped side openings 29 therein within the second chamber 25, the long sides of which are inclined at an angle with respect to the vertical axis of the pipes 24. Four equi-angularly spaced plate-like baffles 30 extend radially inwards from the inner surface of the wall 21a so as to terminate just short of the central vertical axis of the separator. In this embodiment, the upper and lower edges of the baffles 30 are horizontal. Each baffle 30 extends in the vertical direction from just above the watt 21 a to about half the depth of the latter. The inner edges of the baffles 30 are vertical.

The lower ends of each of four cylindrical pipes 31 open into a settlement chamber 32 near to the conjunction of the outer surface of the frusto- conical skirt 14 and the inner surface of the cylindrical wall 12. The settlement chamber 32 is on the opposite side of the frusto-conical skirt 14 to the inner vessel 15. The cylindrical pipes 31 pass vertically upwardly along the outer surface of the cylindrical wall 12 of the vessel 10 and re- enter the vessel 10 so as to open into an annular gutter 33 via a flow control device 34 (in this embodiment a weir). The annular gutter 33 is defined between the inner wall of the vessel 10, the top wall 19 and the outer wall of the inner vessel 15 on the opposite side of the top wall 19 to the nozzle 20.

The lower ends of four cylindrical pipes 35 open into the chamber 23 through the frusto-conical wall 21 a of the funnel 21 at a point proximate to the conjunction of the outer surface of said frusto-conical wall 21a and the inner surface of the cylindrical wall 16. Thetopsofthecy ! indrica ! pipes 35 are bent over so as to open into the gutter 33 via a second series of flow control devices 36 (in this embodiment weirs).

Pipes 37 leading from the top of the flow passage 18 are attached part way up each of the cylindrical sections 28 of the pipes 24. These pipes 37 serve to vent the annular flow passage 18 of air and other gases during filling and in use.

The gutter 33 is connected to a drainpipe 39 which extends downwardly over the outer surface of the outer vessel 10.

A top plate 40 extends completely over the cross-sectional area of the outer vessel 10 so as to close the top of the cylindrical wall 12 of said outer vessel. A hatch (not shown) may be provided in the top cover 40 to enable access to be gained to the interior of the separator to enable periodic freeing, mobilising or cleaning away of any particulates or other build-ups which have accumulated on the interior surface of the separator.

At the base of the outer vessel 10 there is a'T-shaped'pipe connector element 41 with, in this embodiment, two valves 42,43 affixed thereto.

Four overflow pipes 46 (only one shown) are arranged equally spaced around the circumference of wall 16. Each overflow pipe 46 is disposed within the inner vessel 15 at a level just below that of the upper ends of the pipes 24 and discharges into the gutter 33. The radially inward side of the vertical part of each pipe 46 has a vertical slot type of weir to effect flow control.

In use, the vessel 10 is completely filled with clean fluid or the fluid containing particulates to be removed. The fluid containing particulates to be removed is introduced to the annular flow passage 18 via the inlet nozzle 20 with a suitable velocity such as to establish a first helical direction of flow about the vertical axis of the annular flow passage 18.

The driving force impelling the fluid through the separator is the pressure applied at the inlet nozzle 20. The configuration of the inlet nozzle 20 can be chosen to optimise the input bulk flow rate for any given fluid.

The flow rate is controlled so that the bulk velocity of the fluid within the annular flow passage 18 is low and therefore small shear forces are established both between the walls of the flow passage 18 and the lamelle of the fluid. These shear forces establish a second helical motion orthogonal to the first helical flow direction. The annular flow passage 18 therefore forms an agglomeration chamber in which the particulates are gently circulated at low relative velocities such that the opportunity of agglomeration of particulates is enhanced. It also enhances mixing of any chemicals introduced into the fluid either prior to entry into the vessel 10 or internally of the vessel 10 thus optimising the use of feed stream dosing chemicals. Furthermore, this mixing serves to reduce the effects of any thermal or specific gravity variations within the fluid.

The agglomerated particulates are subject to small shear forces which are typically insufficient to facilitate the fragmentation of said agglomerated particles.

As the fluid flows through the annular flow passage 18, it passes the frusto-conical skirt 17 and enters the chamber 23. The baffles 22 within said chamber 23 act to reduce the tangential component of the bulk fluid velocity to a near zero value and also restricts the vertical bulk fluid velocity.

There are three parallel flow paths available to the fluid in this embodiment.

Some of the fluid near to the lower edge of the skirt 17 can enter the lower end of the pipes 24 whereupon it can pass through the shaped openings 29 into the second chamber 25. Agglomerated contaminant particles in this fraction will fall through the funnel-shaped vessel 21 into the settlement chamber 32 leaving an accumulation of clean fluid in the upper levels of the second chamber 25. This relatively clean fluid passes via the overflow pipes 46 into the annular gutter 33.

The level of the fluid in the pipes 24 is above the openings 29 and is such as to maintain a hydrodynamically balanced level between the various chambers of the separation device.

Agglomerated particulates from the flow passage 18 can pass downwardly through the lower opening in the frusto-conical skirt 14, allowing relatively clean fluid to accumulate in the upper part of the chamber 32.

Similarly relatively clean fluid will accumulate in the upper region of the separation chamber 23. The relatively clean fluid accumulated in the chamber 23 and the settlement chamber 32 is drawn slowly up pipes 35 and 31 respectively, thence passing via the flow control devices 36 and 34 respectively into the annular gutter 33.

The nesting of the chambers 23,25 and 32 with vertical separation between them allows the effective cross-sectional settlement area of the separator to be larger than the actual cross-sectional area of the outer vessel 10.

The annular gutter 33 is drained of the cleaned fluid via the drainpipe 39.

The top plate 40, in use, prevents evaporation of the fluid and further prevents eddy currents due to wind shear. The location of the chamber 18 together with thermal insulation (not shown) maintains a substantially uniform temperature within the vessel 10 thereby reducing eddy currents due to thermal effects.

The accumulated particulates within the settlement chamber 32 of the vessel 10 can be removed by opening of the valves 42,43 and naturally draining or pumping. Alternatively or additionally a screw device such as an Archimedean screw conveyor 44 (see Figure 8) or a self-draining bucket conveyor 45 (see Figure 9) or a self-draining screw conveyer (not shown) may be employed.

Each of the conveyors 44 and 45 has a cover 47 thereon to prevent the motion generated by that conveyer from disturbing the settlement taking place in the chamber 32. A similar cover is also provided for the above- described self-draining screw conveyor.

The tapering base of the chamber 32 can serve to compact the particulates and further increase the volume of fluid released. This compacting effect may be enhanced by extending the chamber 32 further downwardly. The compacted form of the particulates is suitable for subsequent processing by conventional means prior to disposal or re-use.

Particulate removal may be effected continuously or as a batch process.

Impact or vibratory means may be provided to facilitate compacting of the particulates in the chamber 32 and/or aid the release of particulates from the chamber 32.

The separator can be configured to separate particulates with differing specific gravities by varying the position of the fluid extraction and particulate extraction points and varying the orientation of the internal frusto-conical sections 14,17, and 21 a to suit the particulate flow direction.

In the case where the fluid contains two types of particulates of which one has a specific gravity which is less than that of the fluid and the other a specific gravity which is greater than that of the fluid, two separators can be arranged in series, each arranged so as to remove one type of particulate in order to achieve the desired degree of separation.

Referring now to Figure 10, this shows a multi-chambered vessel configured in a single separation apparatus to remove particulates with both larger and smaller specific gravities than that of the fluid. Parts of this apparatus which are similar to that of Figs 1 to 8 are accorded the same reference numerals. Inlet nozzle 20, like that of the apparatus of Figs 1 to 8, opens tangentially into annular flow passage 18 adjacent top wall 19 to produce a similar flow pattern.

The upper end of skirt 13 joins cylindrical wall 12 at a level above the lower end of skirt 14. Instead of being joined to cylindrical wall 12, the upper end of skirt 14 is joined to a cylindrical wall 50 disposed between and spaced from walls 12 and 16. Thus, passage 18 is defined between walls 16 and 50. An annular chamber 52 outside the wall 50 is defined by (i) an outward extension of the frusto-conical skirt 14 beyond the wall 50, and (ii) a short cylindrical partition wall 54.

An annular transfer passage 56 is defined between the walls 12 and 54 and extends vertical to approximately midway between top plate 40 and the lower end of the partition wall 54. The region above the upper edge of the partition wall 54 defines a separation chamber 58.

The flow passage 56 need not be annular but may be defined by at least one short pipe extending from the upper edge of the settlement chamber 32 into the separation chamber 58.

At least one pipe 60 opens into the annular chamber 52 at half the depth of the chamber 52 and passes vertically upwardly along the outer surface of the cylindrical wall 50 to open into annular gutter 33 through the cylindrical wall 50 via a flow control device 34.

A weir-type discharge pipe 62 has an inlet opening into the separation chamber 58 at a point near to the top plate 40 and discharges into a gutter 64. The gutter 64 need not be affixed to the outer wall 12.

At least one discharge pipe 66 has an inlet opening into the bottom of the chamber 52 and passes outwardly and downwardly through the wall 12.

The outer end of the pipe 66 has a regulating valve or other flow control device 68.

At least one opening 70 at the upper end of vessel 21 provides communication between the separation chambers 23 and 25. A flow control device 71 (in this embodiment a weir) is mounted inside the chamber 25 slightly below the level of the upper end of the cylindrical wall 16 and discharges into the gutter 64 via a pipe 72.

The flow control device 71 is circumferentially displaced from flow control device 34 so as to prevent mutual interference.

A pipe 73 opens at its lower end into the second chamber 25 below baffles 30. The pipe 73 passes through the upper end of the cylindrical wall 16 and discharges into the gutter 33 via a flow control device 74.

A removable plug 76 in the bottom of the frusto-conical wall 21a allows selective communication between the second chamber 25 and the settlement chamber 32.

The upper ends of vent pipes 37 are positioned above the level of the upper end of the cylindrical wall 16, and are held in position by, for example, clips (not shown).

In use a fluid containing both lighter particulates (i. e. those with specific gravities less than that of the fluid) and heavier particulates (i. e. those with specific gravities greater than that of the fluid) are introduced into passage 18 via nozzle 20.

The annular flow passage 18 forms an agglomeration chamber, as hereinbefore described. The flow paths of the fluid into the chamber 23 and the settlement chamber 32 from the annular flow passage 18 are substantially the same as for the first embodiment of the invention.

The majority of the heavier particulates pass downwardly through the opening in the frusto-conical skirt 14 into the settlement chamber 32, as does a proportion of the lighter particulates, although most of the latter pass into the chamber 23. The heavier particulates accumulate in the tapering base of the chamber 32 and the T-shaped pipe connector element 41 from where they are removed via the valves 42,43.

A portion of the fluid together with lighter particulates within the settlement chamber 32 flows upwardly through the annular flow passage 56 and into the separation chamber 58.

The lighter particulates within the separation chamber 58 continue to flow upwardly and pass, with a small amount of fluid, via the pipe 62 into the gutter 64.

Any remaining heavier particulates which may have been carried into the separation chamber 58 may either flow back down the annular flow passage 56 into the settlement chamber 32 or may flow into the annular chamber 52 to be removed via pipe 66 upon operation of the flow control device 68.

The relatively clean fluid within the annular chamber 52 slowly passes up the pipe 60 and into the annular gutter 33 via the flow control device 34 for removal as described previously.

The majority of the lighter particulates within the chamber 23 will pass through the opening (s) 70 in the vessel 21 into the second chamber 25.

These lighter particulates will continue to flow upwards and are removed, with an amount of fluid, via the flow control device 71 and pipe 72 to the gutter 64.

Any remaining heavier particulates within the second chamber 25 will settle on the plug 76 at the base of the frusto-conical wall 21 a. These particulates are transferred to the settlement chamber 32 by raising the plug 76, by use of a rod, chain or the like 78.

The relatively clean fluid in the region intermediate the upper and lower particulate accumulations within the second chamber 25 passes up the pipe 73 into the annular gutter 33 via the flow control device 74.

Referring now to Figure 11, there is shown a third embodiment of the present invention for separation of lighter particulates (i. e. particulates of a lower specific gravity than the fluid). Parts similar to those of the first embodiment of the present invention, shown in Figure 1, will be accorded the same reference numerals, in the one-hundred series, as those of the first embodiment. It will be appreciated that references to'downwardly convergent'frusta in the description of the first embodiment relate to upwardly convergent frusta in the present embodiment. Similarly references to upper and lower in the description of the first embodiment are reversed in the description of the present embodiment.

In this embodiment, drain pipe 139 for removal of treated fluid leads from a gutter 79 defined by a wall 80 encircling chamber 132, the wall 80 forming an integral extension of the wall 112.

The upper end of the shorter arm of each of four (only one shown) asymmetric'U-shaped'pipes 81 opens into the bottom of separation chamber 123. The'U-shaped'pipes 81 pass horizontally through the outer wall 112 of the vessel 110 and subsequently pass vertically upwards adjacent the external surface of the vessel 110, re-entering the vessel 110 through the wall 80 so as to discharge into the gutter 79 via flow control devices 136. Each of the'U-shaped'pipes 81 has a second flow control device 82 positioned at the lowest point thereof.

The lower end of each of four (only one shown) pipes 83 opens into the settlement chamber 132 near to the base of the latter. Each of the cylindrical pipes 83 passes vertical upward through the upwardly convergent frusto-conical wall section 113 so as to discharge into the gutter 79 via respective flow control devices 134.

There is provided an outlet with a flow control device 84 from the base of the chamber 132.

A cranked pipe 85 opens into second chamber 125 at a level near a base 86 thereof. The pipe 85 passes horizontally through the cylindrical wall 112 and then passes vertically along the outside surface of the vessel 110, re-entering the vessel 110 through the cylindrical wall 80 so as discharge into the gutter 79 via a flow control device 87.

Whilst the base 86 of the vessel 110 is shown as flat, it will be appreciated that any other convenient shape, dependent upon the nature of mounting of the vessel 110, could be used e. g. conical or domed. An appropriate sealable drain (not shown) to drain down the vessel 110 is to be fitted to the base 86.

An outlet with a flow control device 88 and the inlet nozzle 120 are located in the base of passage 118.

A cranked pipe 89 extends from the bottom of each of pipes 124 and passes horizontally through the cylindrical wall 112 to terminate externally of the vessel 110 where it is provided with a flow control device 90.

In use, fluid containing mainly lighter particulates to be separated is introduced via nozzle 120 into the annular flow passage 118 which forms an agglomeration chamber, as hereinbefore described. The flow paths of the fluid into the chamber 123 and the settlement chamber 132 from the annular flow passage 118 are essentially the same as that for the first embodiment of the invention.

The majority of the agglomerated lighter particulates from passage 118 pass into chamber 132 to accumulate in the tapering apex for removal via valves 142,143. The lighter particulates which have entered the chamber 123 with the fluid are free to pass upwardly therefrom through the opening in frusto-conical skirt 114 and into chamber 132.

That portion of the relatively clean fluid which has entered the chamber 132 collects in the bottom of the latter from where it is removed by the pipe 83 and passed to the gutter 79 via the flow control device 134.

Another portion of the fluid flows into the separation chamber 123 at a rate controlled by the rate of fluid extraction. Relatively clean fluid collects in the base of the chamber 123 to be removed via the pipes 81 and discharged into gutter 79 via flow control device 136.

Further portions of the fluid flow downwardly through vessel 121 within pipes 124 into the chamber 125 wherein the relatively clean fluid will collect on the base 86 for removal via pipes 85. The lighter particulates rise through the vessel 121 so as to enter the chamber 132.

Any heavier particulates which may happen to be present in the fluid will sink in the passage 118 and the chambers 132,123 and 125. The flow control devices 82,84,88 and 90 (in this embodiment these are positive flow control devices, e. g. stop valves) allow the periodic extraction of these heavier particulates. If sufficient heavier particulates are present in the fluid and the extraction is frequent enough, the vessel of this embodiment might be suitable for use for the separation of particles with both larger and smaller specific gravities than the fluid.

It wi I I be appreciated that the low rate of movement of the relatively clean fluid allows a layer of agglomerated particulates to form through which the relatively clean fluid passes prior to extraction thereby promoting further agglomeration and increasing particulate agglomerate sizes, together with further cleaning of the fluid.

Referring now to Figure 12, there is shown a fourth embodiment of the present invention, for separation of particulates with a lower specific gravity than the fluid. Parts similar to those of the first and third embodiments of the present invention, shown in Figures 1 and 11, will be accorded the same reference numerals, in the two-hundred series, as those of the first and third embodiments. It will be appreciated that references to'downwardly convergent'frusta in the description of the first embodiment relate to upwardly convergent frusta in the present embodiment. Similarly, references to upper and lower in the description of the first embodiment are reversed in the description of the present embodiment.

A series of ducts 91 pass through frusto-conical wall 221a from chamber 223 and open directly into second chamber 225. <BR> <BR> <P>A plurality of inclined baffles 92, supported upon legs 93, are inclined so as to be parallel with frusto-conical wall 221 a and are located opposite the openings of the ducts 91 into second chamber 225.

A flow control device 94 is located near to the junction of cylindrical wall 212 and base 286.

In use, this embodiment of the present invention operates in substantially the same manner as that of the previous embodiment except as noted here below.

The ducts 91 allow direct flow of the fluid from chamber 223 into chamber 225 wherein baffles 92 and 230 dissipate any residual motion to allow the gentle separation of particulates and fluid without the disturbance of eddy currents. The baffles 230 are circumferentially displaced about the vertical axis of the separator by about 45° relative to the ducts 91.

The flow control device 94 allows the periodic extraction of particulates which have accumulated proximate base 286 of vessel 210.

Instead of weirs as flow control devices any other form of fixed or ajustable device may be employed, e. g. vee notches,'u'notches, overflow pipes, orifices, manual valves, control valves or controlled flow pumps for controlling the flow or level or variations of media density within the various chambers of the separator.