CA1045464A - Cyclone structure - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A cyclone structure is provided for use in controlling the flow of two fluid streams to create a localised inward radial flow. The structure includes a chamber having a side wall disposed concentrically about a longitudinal axis and having first and second transverse end walls attached to respective ends of the side wall. A discharge tube is mounted in the first end wall concentrically about this axis and projects into the chamber. First and second inlets are provided adjacent the respective end walls and means is provided to move fluid under pressure into these inlets and into the chamber.
The fluid enters the chamber in two distinct fluid paths moving vortically about the axis in the same direction of rotation, and the respective energy flow rates of fluid in these paths are comparable. The paths are generally vertical within the chamber and progress axially towards one another before combining where they meet to create the localised inward radial flow. Subsequently, the fluid leaves the radial flow and moves axially towards and out through the discharge tube. A method of providing the radial flow is also described.

Description

1045~64 This invention relates to the creation of a radial flow path in a cyclone structure for use in apparatus such as cyclone furnaces, cyclone mixing devices, and cyclone particle separator5.
Cyclone structures have been used in the past for various purposes and they can be classified according to the fluid path through the structure. Firstly, there are those structures which are essentially cylindrical and which have an inlet in a side wall adjacent one end.
Fluid enters the inlet and proceeds in a vortical fashion along the cylindrical inner wall of the structure before ` leaving via a central axial outlet at the other end of the structure. Examples of patents showing structures using this flow are United States Patents 3,727,563, 3,727,562, 3,757,707, 3,710,558, and 3,119,476.
~, A second cyclone structure uses a flow path , which originates from one end of the structure and discharges !~ ' rroin the same end. Ac¢ordingly, fluid entering the inlet moves vortically along a cylindrical inner wall before 20 meeting an end wall whereupon the path is deflected radially inwards and turned through 180 degrees before passing axially to a central outlet at the same end as the inlet.
This compound cyclonic flow is used in structures described in United States Patents 3,096,275, 3,283,480, 2,881,720,

2,881,719 and 2,207,444.
It has been found that a cyclonic flow can be provided which has a variable path and which has advantages in many structures such as furnaces, mixing devices, and separators. Essentially, a radial flow is 30 provided intermediate the ends of a cyclone structure and this radial flow can be moved axially with reference to the ends ~ ' - ~ !

of the structure for various purposes.
Accordingly, in one of its aspects, the present invention provides a cyclone structure for use in controlling the flow of two fluid streams ~o create a localised inward radial flow. The structure includes a chamber having a side wall disposed concentrically about a longitudinal axis and having first and second transverse end walls attached to respective ends of the side wall. A discharge tube is mounted in the first end wall concentrically about this axis and projects into the ¦
chamber. First and second inlets are provided adjacent the respective end walls and means is provided to move fluid under pressure into æhesé inlets and into the chamber.
The fluid enters the chamber in two distinct fluid paths ' moving vortically about the axis in the same direction of rotation, and the resepctive energy flow rates of fluid in these,paths are comparable. The paths are generally vortical within the chamber and progress axially towards : ..
,, one another before combining where they meet to create the localised inward radial flow. Subsequently, the fluid leaves the radial flow and moves axially towards and out ; through the discharge tube.

.! In another of its aspects, the invention provides a method of creating a radial flow from two distinct supplies of fluid. The method includes the steps of creating a first vortical flow from a first of the supplies of fluid such that the flow progresses along a longitudinal axis, and simultaneously creating a second vortical flow from a second of the supplies of fluid. This second vortical flow moves in the same direction about the a~is and has an energy flow rate comparable to that of the

- 3 -1~45464 first vortical flow. The second vortical flow progresses along the axis in the opposite direction to that of the first vortical flow and the first and second vortical flows are permitted to ` meet while preventing outward movement of the flows to thereby create a localised inward radial flow. Discharge from the in-ward radial flow is provided by an axial flow within one of the first and second vortical flows.
In accordance with a preferred embodiment of the present invention, there is provided an incinerator structure . 10 for burning waste products and the like, comprising:
a combustion chamber having a side wall disposed concentrically about a longitudinal axis and first ;
and second transverse end walls attached to the respective ends of the side wall;
a discharge tube mounted in the first end wall concentrically about said axis and extending into said chamber a relatively minor distance with respect to the longitudinal axial length of the chamber;
first and second inlets adjacent said first and second end walls respectively;
means coupled to the first inlet and adapted to move said waste products and primary air through the first inlet and into the combustion chamber;
means coupled to the second inlet and adapted to move secondary fuel and secondary air through the second inlet and into the combustion chamber; and ignition means adapted to ignite the secondary fuel to cause combustion adjacent the second end wall, said inlets being arranged to direct the materials passing therethrough towards the side wall of the chamber in generally vortical paths _ 4 _ ,. . . .

whereby the materials in said paths move towards each other axially within said chamber adjacent the side wall thereof to form an inward radial flow where the major portion of the combustion of the waste products takes place, the products of combustion then moving axially within the first fluid path before leaving the combustion chamber through the discharge tube and the waste products and primary air being heated as they move axially . 10 towards the radial flow path by the products of combustion passing axially through the combustion :~ chamber.
In accordance wi*h a further preferred embodiment . of the present invention, there is provided a separator , structure for removing particulates and the like from a ' fluid, comprising:
1 .
a chamber having a side wall disposed concentri-cally about a longitudinal axis and having transverse end walls attached to the respective ends of the side wall;
a discharge tube mounted in one end wall concentri-cally about said axis and extending into said chamber a relatively minor distance with respect to the longitudinal axial length of the chamber;
a pair of inlets, each inlet being adjacent a respective one of the end walls;
a particulate collection outlet attached to the side wall intermediate the end walls for channeling at least a portion of the particulates out of the chamber;

means coupled to one of the inlets and adapted to move a fluid carrying particulat~sinto the 4a -''''~S

chamber through said one of the inlets; and means coupled to the other of the inlets and adapted to move a control fluid through said other of the inlets;
said inlets being arranged to direct the materials passing therethrough towards the side wall of the chamber in generally vortical paths whereby the materials in said paths move towards each other axially within said chamber adjacent the side wall thereof to form an inward radial flow and an annular quiescent zone about said radial flow, and said means coupled to the inlets J( being capable of controlling the energy flow rate , of the particulate carrying fluid and/or of the control fluid so that the quiescent zone is , aligned with the particulate collection outlet.
~3. In accordance with a still further preferred embodiment of the present invention, there is provided a method of burning waste products and the like, comprising the steps of:
. providing a combustion chamber having a side wall .~'. which is substantially symmetrical about an axis, .~
end walls attached to respective ends of the side wall, a discharge outlet in one of said end walls substantially concentrically about the axis, and first and second inlets adjacent respective said end walls;
directing waste products and primary air through said first inlet and into said combustion chamber in a first generally vortical flow path which pro-gresses axially toward the second end wall adja-cent the side wall of the chamber;

~ - 4b -1al4S464 directing secondary fuel and secondary air through said second inlet into said combustion chamber in - a second vortical flow path which progresses axially toward the first end wall of the combustion :~ chamber adjacent the side wall of the chamber and which moves about the axis in the same direction as said first flow path;
igniting said secondary fuel to cause combustion adjacent said second end wall;
~:i 10 permitting the flow paths to meet intermediate the - end walls thereby creating an inward radial flow path where the major portion of the combustion of the waste products takes place, the products of combustion then moving axially within the first fluid path before leaving the combustion chamber through said discharge outlet, and the waste products and primary air being heated as -' they move towards the radial flow path by the ` products of combustion passing axially through ~ the combustion chamber.
In accordance with a still further preferred : embodiment of the present invention, there is provided a method of separating particulates from a particulate laden fluid comprising the steps of:
creating a first vortical flow rom said fluid within a chamber having a side wall, the flow progressing along a longitudinal axis and adjacent the side wall of said chamber;
creating a second vortical flow from a control fluid, said flow progressing along said axis and adjacent the side wall of said chamber, in the opposite direction to that of the first vortical ~, ~ - 4c -, ~
~, ~i flow while rotating in the same direction about said axis;
permitting the first and second vortical flows to meet while preventing outward movement of the flows to create an inward radial flow encompassed at the outer periphery thereof by a quiescent zone into which at least some of the particulates collect;
and removing said collected particulates through an outlet from said quiescent zone.
It is also within the scope of the invention to pro-vide mixing devices, furnaces, and separators incorporating the aforementioned radial flow.
~, The invention will be better understood with refer-~ ence to the drawings, in which:
;~ FIGURE 1 is a diagrammatic view of a longitudinal j section of a preferred embodiment of a cyclone struc-,~ ture according to the invention;
, , ~ FIGURE 2 is a view similar to Figure 1 and illus-, .. .
trating an exemplary use of the cyclone structure in an incinerator arrangement; and FIGURE 3 is a view similar to Figure 2 and illus-` trating the cyclone structure in use in a separator arrangement.
` Reference is first made to Figure 1 which shows a cyclone structure 20 consisting of a chamber 22, discharge tube . 24, and respective inlets 26, 28.
The chamber consists essentially of a cylindrical side wall 30 terminating at an annular end wall 32 surrounding the discharge tube 24, and a circular end wall 34. The side wall 30 is concentric about a longitudinal axis indicated by the numeral 36 and the discharge tube 24 is also concentric about this axis. As may be seen from Figure 1, discharge tube 24 ex-tends into chamber 22 for only a relatively short distance. End walls 32 and 34 are transverse with respect to the axis and the inlets 26, 28 are positioned in the side wall 30 to create vortical - 4d -~s flow within the chamber 22. This is achieved in conventional fashion by arranging for the inlets to be substantially tangen-tial with respect to the c~rcular circumference of the side wall 30. As shown in Fig. 1, the inlets 26, 28 are substantially parallel to one another.
The principle of operation will be described with reference to Fig. 1 and it will be assumed that a pair of fans 38, 40 coupled to respective inlets 26, 28 are blowing air through these inlets to create two distinct vortical flows which rotate in the same direction about axis 36. It will be under-stood that the definition of the vortical flows rotating in the same direction about the axis means that when the two indivi-dual flows meet, they are cocurrent.
The energy flow rates through the inlets are of com-parable magnitude although they can be adjusted as will be described. Air from the fan 38 results in a vortical flow indicated by a curved arrow 42, and similarly, the fan 40 creates a vortical flow indicated by the arrow 44. Each of the vortical flows must progress axially due to the proximity with the respective end walls 32, 34. Consequently, these vortical flows will progress until they meet as indicated in chain dotted outline in Fig. 1. At the point where they meet, the axial components of the energy in the vortical flows are sub-stantially equal so that there is an axial balance. However, the fluids in the respective flows must continue to move and consequently they will move radially inwards until they are deflected by a pressure build-up at the axis 36. The fluids ' will then have a free path through the discharge tube 24 as indicated in chain dotted outline in the tube 24.
It will be appreciated that the junction between the vortical paths 42 and 44 will have an external peripheral zone 46 which is substantially quiescent because it lies outside of the vortical paths where they become radial. Both the annular zone of reduced flow energy, and the radial /

1~45464 . flow effect can be used for various purposes as will be described.
The radial flow may of course have a less distinct pattern than that illustrated in Fig. 1.
~owever, for the purposes of this description the term I ~.
"radial flow" means any flow which moves radially inwards, lies in a relatlvely narrow band, and is stable so that .
it can be used with predictable results.
The position of the radial flow depends upon the energy flow rates o~ the air coming from each of the inlets 26, 28... In $he event that the flow rate is adjusted so that there.-is-an increase through the inlet 26 with ` respect to the inlet 28,.then the radial path will move `~ towards the inlet 28. ~onversely, if the energy flow rate is increased-through the.inlet 28 with respect to the ~ inlet 26, then the radial flow will move towards the inlet 26. .It has been found.that there is an inherent stability in the position of the radial flow once the adjustment is.complete and consequently it would be ~; 20 possible .to calibrate equipment to predict the position .~ - . I
- of the radial flow for particular fluids and flow rates.
The side wall 22 need not necessarily be strictly cylinarical. ~owever it :should be symmetrical around the . axis 36 and any deviation from cylindrical must be within the practical confines of operability. Any shape which prevents the efficient creation of vortical paths and the subsequent combination of these paths into radial flow would be unsatisfactory.
The structure shown in Fig. 1 has been described : 30 ~Jith reference to air entering both inlets. It will be appreciated that any gaseous fluid can be substituted for one or both air inputs and that solid particles or particulates can be carried in the gaseous stream. Such inputs are within the scope of the term 'fluid' used in ( this description.
- The Fig. 1 structure could also be used with two liquids with or without added solids. These are also within the scope of the term 'fluid' as used in this application, although it will be appreciated that the term does not include the use of a gaseous fluid in one inlet and a-liguld in the other lnlet.
The inventive concept of providing a radial fluid flow within a cyclone structure has numerous applications. An exemplary application is illustrated in Fig. 2 in which parts corresponding to those described ^ with reference to Fig. 1 are given primed numerals.
~; As seen in Fig. 2, an incinerator 48 includes a chamber 22' which differs from the chamber 22 shown in Fig. 1 in that an end wall 50 is provided corresponding generaI~y to end wall 34. End wall 50 has a generally .. . _ . :
annular section 52 surrounding an inset generally cylindrical .~ i portion 54. The purpose of this end wall is to collect slag as will be described.
, The chamber 22' is in fact a combustion chamber ; in this structure and is arranged with axis 36' vertical.
, Primary air and waste material to be burned in the ; incinerator are fed from a feeder 56 through inlet 26' and proceed in the vortical path 42'. Similarly, secondary fuel and secondaryair are moved by feeder 58 into ; vortical path 44'. The primary air and secondary air are fed in comparable energy rates so that a radial flow is created in a lower portion of the vertical combustion chamber 22'. Consequently, the primary air and waste fuel .

1~4546~
move along the inside wall o~ the chamber where they are heated by radiant heat emanating from exhaust gases passing axially upwards and out through the dIschar~e tube 24'. The initial preheating continues until the primary air and lighter parts of the waste fuel begin to move radially where they combine with burn;ng secondary fuel in an oxygen rich high temperature zone where the main combustion takes place. The combustion will continue for a portion of the distance travelled in the central path between the radial flow and the discharge tube 24'.
Consequently, it can be said that the incinerator includes a preheating zone where the waste fuel is heated as it moves down-wardly, a main or secondary combustion zone where the movement is radial, and a tertiary combustion zone where final combustion takes place as the movement continues towards the discharge tube 24'.
When certain types of waste material are being incin-erated, there is generally about 5 to 6 per cent slag in the form of glass. This is melted in the incinerator mainly in the ` secondary combustion zone and falls towards the bottom of the incinerator. It is collected on the annular portion 52 of the end wall 50 and is allowed to exit through a discharge port 60 where it falls into a quenching bath 62. A spiral feeder 64 then transports the cold glass particles into a hopper 66.
The use of slag is advantageous in that it tends to -~ collect fine particles which would otherwise be discharged through the tube 24'. Consequently when burning wood or other substances where no natural slag occurs, a synthetic i slag (such as that collected in the hopper 66) is mixed with the solid fuel and fed through the inlet 26~ to create a slag flow for collecting small particles.

1~45464 The incinerator will of course be lined with fire resistance material as is common in the art. Also, ( the shape of the side wall 30' can be varied as was discussed with reference to Fig. 1. In particular it may be preferable to vary the shape of the side wall to take into consideration changes in volume of gases caused by heating.
In use, the quiescent zone 46' tends to collect heavier unburnt particles because t-heircentrifugal force is greater than the drag which would otherwise carry them radially inwards. These unburnt particles will either be collected in the slag or they will rotate and break up and eventually be carried by the passing fluids into the main stream where they are burnt. Consequently, the arrangement tends to limit the possibility of unburnt -~ heavier particles being discharged through the tube 24'.
There is therefore a longer particle retention within the cyclone where particles would otherwise be lost without . .
proper burning. Further, the length of the path followed by the solid fuel can be varied by changing the relative energy in~uts between the inlets 26' and 28' as was discussed with reference to Fig. 1. For instance, if light material which burns readily is being incinerated, the time within the incinerator can be reduced by effectively moving the radial flow upwardly towards inlet 26'.
The incinerator is shown with the axis 36' vertical. However, this can be inclined towards the horizontal in which case the discharge port 60 would be po-sitioned at a lower point in or adjacent the end wall 50 for ready discharge of the slag. It is also possible to - have the axis 36' horizontal if a drainage trough is ., '~ ' 1C~45~164 developed in the fire bricks in the side wall. However if a fuel is used which has no slag, the axis can be horizontal without special arrangements for disposing of liquid slag.
A further feature of the arrangement of the incinerator is that the extremetemperatures do not occur on the lining of the incinerator. Because of the flow of both the primary and secondary air, the major burning takes place in the radial flow. Consequently the largest temperatures tend to occur remote from the side wall.
Also, where different fuelsare used, the ,axial position of the radial flow will be adjusted in each case depending , upon the time required for incineration. This will reduce local attrition at a particular part of the combustion chamber wall and enhance the life of the combustion chamber. In some instances the adjustment can be made cyclically to move the position of the radial flow continuously betwe,en limits. This is done by using a .. . .
'l, motor driven valve 61 on the fan inlet 28' as indicated in broken outline. The valve 61 can be in the form of a butterfly valve which when in the maximum throttling ~ position causes the radial flow to reach a lower or '~ minimum level and which when fully open causes the radial flow to reach an upper or maximum level. The effect of such a valve is twofold. Firstly the attrition of the fire wall is limited because the hottest parts ' are moving continuously, and secondly if slag builds up , ~ on the wall it will be cyclically heated to melt it and ' thereby clean the wall.
Yet another advantage is that slagging occurs , . , ,, I
' - 10 -1~4S464 in the hottest area. Cold primary air lS preheated and involved in primary conbustion before it reaches the slagging zone. Consequently the primary air has little effect on cooling the slag so that there is less possibility that glass will solidify within the incinerator and will then have to be removed manually after the incinerator is cooled. This is an important aspect when handling waste materials with a high slag content.

Reference is now made to Fig. 3 which illustrates a further exemplary use of the cyclone structure-described with reference to Fig. 1. Parts shown in Fig. 3 which correspond to those used in Fig. 1 will be given double primed numerals. As seen in Fig. 3, axis 36" is vertical and the side wall 30" is interrupted by a scroll outlet 70 located for receiving particulates which are separated from an input as will be described. ~ -The end of the chamber 22" remote from the discharge,tube 24" differs from the corresponding end plates previously described. An end wall 72 is provided which has a frustro-conical profile and which terminates : i , in a downward outlet tube 74. The end wall 72 and tube 74 are symmetrical about the axis 36". Also, a conical baffle 76 is provided to encourage the formation of the vortical path 44".
- In use, a feeder 78 moves particulate laden fluid into the chamber 22" by way of the inlet 28".
Heaviér particles will immediately fall onto the end plate 72 and subsequently through the tube 74. Light and , intermediate particles will remain in the fluid stream and follow vortical path 44". Similarly, feeder 80 moves a control fluid through the inlet 26" to create the vortical path 42". Paths 42" and 44" meet at a radial ., 1~45464 flow aligned with the scroll outlet 70. Consequently, the intermediate particulates in the stream emanating from the feeder 78 will find their way to the quiescent zone 46" and centrifugal force will carry them into the scroll outlet 70 while the light particles will be carriea out through the discharge tube 24" for separation in a filter.

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Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A cyclone structure for use in controlling the flow of two fluid streams to create an inward radial flow, the structure comprising:
a chamber having a side wall disposed concentrically about a longitudinal axis and having first and second transverse end walls attached to the respective ends of the side wall;
a discharge tube mounted in the first end wall concen-trically about said axis, said tube extending into said chamber a relatively minor distance with respect to the longitudinal axial length of the chamber;
first and second inlets adjacent said first and second end walls respectively, and means coupled to the inlets and adapted to move fluid under pressure through the inlets and into the chamber in two distinct fluid paths, said inlets being arranged to direct the fluid moved there-through towards the side wall of the chamber in generally vortical paths whereby the fluids in said paths move towards each other axially within said chamber adjacent the side wall thereof and combine to form an inward radial flow before moving axially towards and out through the dis-charge tube.

2. An incinerator structure for burning waste products and the like, comprising:
a combustion chamber having a side wall disposed concen-trically about a longitudinal axis and first and second transverse end walls attached to the res-pective ends of the side wall;

a discharge tube mounted in the first end wall concen-trically about said axis and extending into said chamber a relatively minor distance with respect to the longitudinal axial length of the chamber;
first and second inlets adjacent said first and second end walls respectively;
means coupled to the first inlet and adapted to move said waste products and primary air through the first inlet and into the combustion chamber;
means coupled to the second inlet and adapted to move secondary fuel and secondary air through the sec-ond inlet and into the combustion chamber; and ignition means adapted to ignite the secondary fuel to cause combustion adjacent the second end wall, said inlets being arranged to direct the materials passing therethrough towards the side wall of the chamber in generally vortical paths whereby the materials in said paths move towards each other axially within said chamber adjacent the side wall thereof to form an inward radial flow where the major portion of the combustion of the waste prod-ucts takes place, the products of combustion then moving axially within the first fluid path before leaving the combustion chamber through the dis-charge tube and the waste products and primary air being heated as they move axially towards the radial flow path by the products of combustion passing axially through the combustion chamber.

3. An incinerator according to claim 2, comprising a slag outlet positioned to permit gravitational flow of molten slag from the combustion chamber.

4. An incinerator according to claim 3, comprising a slag collection system for collecting reusable slag, said system comprising a water quench located adjacent the slag out-let and means for collecting the quenched slag and storing it for future use with material which will not slag sufficiently to control small particulates.

5. A separator structure for removing particulates and the like from a fluid, comprising:
a chamber having a side wall disposed concentrically about a longitudinal axis and having transverse end walls attached to the respective ends of the side wall;
a discharge tube mounted in one end wall concentrically about said axis and extending into said chamber a relatively minor distance with respect to the longitudinal axial length of the chamber;
a pair of inlets, each inlet being adjacent a respec-tive one of the end walls;
a particulate collection outlet attached to the side wall intermediate the end walls for channeling at least a portion of the particulates out of the chamber;
means coupled to one of the inlets and adapted to move a fluid carrying particulates into the chamber through said one of the inlets; and means coupled to the other of the inlets and adapted to move a control fluid through said other of the inlets;
said inlets being arranged to direct the materials passing therethrough towards the side wall of the chamber in generally vortical paths whereby the materials in said paths move towards each other axially within said chamber adjacent the side wall thereof to form an inward radial flow and an annular quiescent zone about said radial flow, and said means coupled to the inlets being capable of controlling the energy flow rate of the particulate carrying fluid and/or of the control fluid so that the quiescent zone is aligned with the particulate collection outlet.

6. A separator according to claim 5, wherein the chamber has its side wall disposed concentrically about a vertical longitudinal axis and comprising a second particulate collec-tion outlet mounted in the lower end wall of the chamber for channeling heavier particulates out of the chamber under the influence of gravity.

7. A structure according to claim 1, 2 or 5, wherein the side wall of the chamber is cylindrical.

8. A structure according to claim 1, 2 or 5, wherein the means coupled to the inlets for moving fluids into the chamber are capable of controlling the energy flow of at least one of said fluids in order to control the position of said inward radial flow.

9. A method of creating a radial flow from two distinct supplies of fluid, the method comprising the steps of:
creating a first vortical flow from the first of the supplies of fluid within a chamber having a side wall, the flow progressing along a longi-tudinal axis and adjacent the side wall of said chamber;

creating a second vortical flow from the second of the supplies of fluid, said flow progressing along said axis and adjacent the side wall of said chamber in the opposite direction to that of the first vortical flow while rotating in the same direction about the axis;
permitting the respective first and second vortical flows to meet while preventing outward movement of the flows to thereby create an inward radial flow; and providing discharge from the inward radial flow by an axial flow within one of the first and second vortical flows.

10. A method of burning waste products and the like, com-prising the steps of:
providing a combustion chamber having a side wall which is substantially symmetrical about an axis, end walls attached to respective ends of the side wall, a discharge outlet in one of said end walls sub-stantially concentrically about the axis, and first and second inlets adjacent respective said end walls;
directing waste products and primary air through said first inlet and into said combustion chamber in a first generally vortical flow path which pro-gresses axially toward the second end wall adja-cent the side wall of the chamber;
directing secondary fuel and secondary air through said second inlet into said combustion chamber in a second vortical flow path which progresses axi-ally toward the first end wall of the combustion¦

chamber adjacent the side wall of the chamber and which moves about the axis in the same direction as said first flow path;
igniting said secondary fuel to cause combustion adja-cent said second end wall;
permitting the flow paths to meet intermediate the end walls thereby creating an inward radial flow path where the major portion of the combustion of the waste products takes place, the products of combustion then moving axially within the first fluid path before leaving the combustion chamber through said discharge outlet, and the waste products and primary air being heated as they move towards the radial flow path by the products of combustion passing axially through the combustion chamber.

11. A method of separating particulates from a particulate laden fluid comprising the steps of:
creating a first vortical flow from said fluid within a chamber having a side wall, the flow progres-sing along a longitudinal axis and adjacent the side wall of said chamber;
creating a second vortical flow from a control fluid, said flow progressing along said axis and adja-cent the side wall of said chamber, in the oppo-site direction to that of the first vortical flow while rotating in the same direction about said axis;
permitting the first and second vortical flows to meet while preventing outward movement of the flows to create an inward radial flow encompassed at the outer periphery thereof by a quiescent zone into which at least some of the particulates collect; and removing said collected particulates through an outlet from said quiescent zone.

12. A method according to claim 9 or 10, including the step of adjusting the axial position of the radial flow path.