AU610007B2

AU610007B2 - Cyclone separator

Info

Publication number: AU610007B2
Application number: AU38857/89A
Authority: AU
Inventors: Gavan James Joseph Prendergast
Original assignee: Conoco Specialty Products Inc
Current assignee: Lubrizol Specialty Products Inc
Priority date: 1984-01-24
Filing date: 1989-07-21
Publication date: 1991-05-09
Anticipated expiration: 2005-01-24
Also published as: DK373285D0; WO1985003242A1; ES539761A0; AU3886685A; IT8547591A1; IT1182146B; BR8504916A; MY102231A; EP0203065A4; CA1269952A; IL74139A; NO853723L; GB8617436D0; ES8608342A1; NO168993B; CU21960A1; DK164575B; ZA85547B; IN164072B; DE3579162D1

Description

901 101,dbwdat.033,c2,I,2

I

9 COM MON W EA LT H 0OF A UST R ALI A PATENT ACT 1952 COMPLET PECFIATIiOOO

(ORIGINAL)

FOR OFFICE USE CLASS INT. CLASS App~licationl Number: Lodged: Complete Specification Lodged: Accepted: c Published: o Priority: Related Art-: This document contains the am-1endmients made under Section 49 amd is correct f Or printing.

co~cc~cz~ 00 0 0 0 0

I

I 884 08 o C

I

NAME OF APPLICANT: ADDRESS OF APPLICANT: ILStra-thaLby-nI *1 n 1 -The--r-escent Q Q -Gommonwea-1-t-h-o-f-Austra-4ia NAME(S) OF INVENTOR GAVAN PRENDERGAST ADDRESS FOR SERVICE: DAVIES COLLISON, Patent Attorneys I Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: "CYCLONE SEPARATOR" %'he following statement is a f ull. description of this inventione fi.ncladinq the best method of performing it known to us

-I-

CYCLONE SEPARATOR This invention relates to a cyclone separator for separating a denser liquid component of a liquid mixturn from a less dense liquid component thereof.

A separator of-the above kind is described in Australian patent specification 559,530. This separator has proven to be successful in applications involving separating small quantities of oil from oil-water mixtures. The separator does however require two inlets. This is inconvenient in some applications and an object of the invention is to provide a cyclone separator for separating a denser liquid component of a liquid mixture from a less dense liquid component thereof and which has an inlet configuration permitting less than two inlets to be employed if required.

t v 4 0 0 0 0 00000 15 0 0 0 00 0 0 In accordance with one aspect of this 0 invention there is rovided a cyclone separator for separe'Cing a denser omponent of a liquid mixture from a Ie^ss dense'component thereof, said separator 00 9 being of a kind having an axially extending at separating chamber having towards one end inlet means for admission of the mixture with a tangential flow component, the separating chamber having an axially positioned overflow outlet adjacent said one end and said separating chamber of generally tapered form with a relatively larger cross-sectional size at said one end and a relatively small cross-sectional size at an axially positioned underflow outlet at the end of the separating chamber opposite said one end, i-i 2 wherein in use the denser component is directed to the underflow outlet in a fashion such as to encompass an inner axially positioned core of the less dense component which is subjected at least over a substantial part of its length to a pressure differential causing it to flow to the overflow outlet, said inlet means being defined by a portion of the separating chamber and at leadt oneinlet tract communicating with said portion, said portion being that portion of the separating chamber which is So at the same lengthwise position as the or each inlet tract, wherein the or each inlet tract presents inner 00O, and outer profiles, when viewed axially of the o 09 o oo separator, said outer profile extending from a first 0 15 location at which it meets the circumference of said 0 0 portion of the separating chamber and at least the inward projection of said inner profile extending from a second location at which the inner profile or 0 its said projection meets said circumference, said ^0 profiles being -chasr-ctorisd -nhthat: S0 0 0 00 0 0 Qo oo a first vector T describing the location of 0 0 o ooo any particular point on said outer profile and contained in a plane normal to said axis, and having its origin at said first location, is such that as the magnitude oe the vector T increases, an angle 0° 98 between the vector T and that tangent to said circumference which passes through said first location never decreases and never becomes less than zero for all magnitudes of vector T less than h D, a second vector U, describing the location of any particular point on the inner profile and having its point of origin at said second location is 2a such that as the magnitude of vector U increases, an angle between vector U and that tangent to said circumference which passes through said second location never decreases and never becomes less than zero for all magnitudes of vector U less than aD at least for substantial magnitudes of vector U, 'D being the length of the outer profile of the inlet tract, viewed axially of the separating chamber, D beinj the diameter of said portion of the o"10 separating chamber 0a0 0 0 aD being the length of the inner profile of the 0 0 o e inlet tract viewed axially of the separating chamber, ao 10 D being measured from a first location at which the 0o outer profile meets the circumference of its portion of the separating chamber and aD being measured from a second location at which at least an inward oo0o projection of t'e inner profile meets said circumference.

o o 0 0 0 A particular form of profile in accordance 0 0 r°°20 with the invention is an involute form arranged to admit the liquid in a spiral path.

o It has been found that with profiled inlets 0 a in accordance with this invention, it is not necessary to provide more than one inlet opening.

The invention is further described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional diagram of a separator constructed in accordance with the invention; 2b Figure 2 is a cross-section substantially on the line 2-2 in Figure 1; Figures 3 and 4 illustrate alternative forms of an end wall of the separating'chamber of Figure 1; Figure 5 shows an alternative form of the overflow outlet for the separator of Figure 1; Figure 6 is a detailed axial cross-sectional view of the inlet means of a separator constructed in" accordance with the invention; 0 0 0 oo o n 00 B 0 0 0 0 00 0 a 0 0 00 a 0 0 0 a G!o 0 0 a 00 0 00 0 ot 00 0 0 00 0 00 0 00 0 coo C00 0P C 0 Figure 7 is a diagram like Figure 6 but showing preferred inlet tract profiles; and Figure 8 is a fragmentary axial diagram of a modified inlet tract.

The separator 10 comprises a separating chamber 12 having three coaxially arranged separating chamber portions 14, 16, 18 of cylindrical configuration.

These are of diameters and lengths d,,1 1 d 21 1 2 and d 3 ,1 3 respectively. Portion 14 is of greater diameter than portion 16 and portion 18 is of lesser diameter than portion 16. As described in the specification of Patent Application PCT/AU83/00028, a flow restricting mean's (not shown) may be provided at the outlet from the cylindrical portion 18 but in this instance the outlet end is shown as being provided by an underf low 15 outlet 24 from cylindrical portion 18. A tapered section 17 may be provided between portions 14 and 16.

Although the portion 16 shown exhibits a first section of parallel sided form followed by a tapered section, in practice, it is possible to form portion 16 as 20 having a constant taper over its length.

An involute inlet pipe 20 is provided to the separating chamber portion 14, this opening into a side wall of the separating chamber at an inlet opening 23. An overflow outlet 25 is provided on the axis of the sepairating chambd~ar portion 14, this leading to an axial overflow pipe 27. As shown in Figure 2, the involute inlet pipe 20 spirals around the periphery of the separating chamber portion 14 and exhibits a gradually decreasing cross sectional area as it approaches the opening 23. The pipe 20 and opening 23 may be of rectangular cross section.

In use, the separator 10 functions generally in accordance with pzst practice in that the liquid 12/ d 2 0.04 4Ai/ Trdt 0.10 0.1 do/d 2 0.25 d d 2 d 2 d 3 C t where A is the total cross-sectional area of the feed i inlet, provided by inlet opening 23, d is the diameter of the overflow outlet 25 and the remaining o terms have the meanings ascribed to above. Also, in 0 00 10 the specification of Australian Patent Application No.

84713/82 a variant construction is described having parameters as above described save for the ratio d /d 2 which is specified in that case to be less than 0.1.

o Separators constructed in accordance with this variant 00 0 0 00 15 form may also be adapted for use in the present 0 00 invention. Generally, in any event the separator of this invention may advantageously be characterised by 0 b having the ratio 1 2 /d 2 at least equal to 10. Also, for separators intended for separating relatively 20 small quantities of less dense liquid, such as oil, from relatively larger quantities of more dense liquid such as water, the ratio dl/d 2 may be in the range to 3.0, such as However, it has been found in practice that it is not necessary to adhere to the range of overflow outlet dimensions described above.

Referring now to Figure 6 an inlet profile of the invention is shown in more detail. Here, the inlet 6 means of the separator is shown as comprising an inlet tract 80 together with a portion of the separating chamber of the separator which is lengthwise adjacent thereto. In this regard, generally, although the separator shown in Figure 1 is described as having three distinct portions of successively decreasing diameters, it is not essential that the separator be so formed as it could, for ex-ample, exhibit any generally tapered configuration extending from a larger diameter end adjacent the overflow outlet to a 10 smaller cross section end adjacent the underflow C tr a outlet. The tract 80 is shown as having an outer profile 82 and an inner profile 84. Here, the 0.0 diameter D of the cyclone separator as shown in Figure 0, 6 corresponds to the diameter d 1 in Figure 1, since 0 0 the inlet tract 80 (as in the case of the Figure 1 construction) communicates with the separating chamber at the larger diameter end thereof.

0 The tract 80 is considered as extending from a 00 0 ooo location indicated generally by reference numeral inwardly towards the separating chamber.' The location °o 85 is defined as a point beyond which, reckoned in the 0 oo direction inwardly towards the separating chamber the flow of inlet liquid cannot be described by the simple flow equations. More particularly, the points 83, 87 25 on the outer and inner profiles aligned with location 0 a% are points where, if the profiles were projected outwardly therefrom in parallel relationship the separator would operate substantially the same as if the profiles were continued in the profiled configurations defined in accordance with this invention.

By the term "outwardly projected" is meant a projection from the respective profile which is substantially tangential at the point of meeting the 7 respective profile. From the respective points 83, 87 on the outer and inner profiles respectively the profiles extend in spiral fashion inwardly to meet the circumferential surface 86 of the separating chamber. Locations at which the profiles so meet circumference 86 are designated respectively by letters and Practically, although the 7°,o profile 84 is shown as joining circumference 86 by o o continuance of the profile inwardly until it meets 0 0 9 i10 the circumference 86 at the point for mechanical °0 o reasons it is frequently simpler and more effective

S

o 0 0 to round the junction between the profile 84 and the 0 circumference 86 by providing a rounded portion 84a (indicated by broken lines).

The inner and outer profiles preferably generally described by the following equations: oo00 0 0 0 00 0 hc r I2+o( 0000 9 0 no 0°o 0.35 1.5, where fD is the length of the outer profile 82 of the gooo 20 inlet tract, viewed axially of the separating chamber, D being the diameter of the portion of the separating chamber at which circumference .86 prevails. That is to say, h=where F is the length of the outer profile and D is as just defined. This profile length is that extending between points and 83. aD is the length of the inner profile 84, viewed axially of the separating chamber. Thus, a is the ratio f

D

where G is the length of the inner profile and D is

I

8 as previously defined. This profile length is that extending between points and 87.

Generally, the outer profile 82 is such that vector T describing the location of any particular 5 point on outer profile and contained in a plane normal to said axis, and having its origin at 0 0 0o 0 0 0o 0 00 00 00 00 00 00 0

*O

000 00 0 4 0 00 00 0t t l 4 )t 8a location is such that as the magnitude of the vector T increases, an angle 0 between the vector T and a tangent 92 to circumference 86 passing through said location never decreases and never becomes less than zero for all magnitudes of T less than D Similarly, a vector U, describing the location of any particular point on the inner profile 84 and'having its point of origin at location is such that as the magnitude of vector U increases, the So 10 angle between vector U and a tangent 93 to said o circumference which passes through said location 0 never decreases and never becomes less than zero, for 0 oo all magnitudes of vector U less than aD, at least .0 00 o0 o0 for substantial magnitudes of vector U, where cD is the length of the inner profile viewed axially of the separating chamber. This profile length is that extending between points and 87. By substantial 'o0 magnitude of vector U, we mean that in the vicinity 0o°o of the location vector U may not be defined because of possible rounding of the inner profile as previously described.

The cross-sectional area A of the tract measured in a radial and axial plane passing through the location where the inner profile 84 25 actually terminates (location or the extremity of the portion 84 as the case may be) is preferably defined as: 2 0.04 4 A /TD 0.1 outlet in a fashion such as to encompass an inner axially positioned core of the less dense component which is subjected at least over a substantial part of its length to a pressure differential causing it to /2 t- ~lr- ri 8b It is also preferred that the following relationship hold between the constants h and a, Y 1Tr 0e

I

c 0 0 4u 0r *1 0 0E 0 *0 0 0 I 1.

The described relationship between the constants a and q is most appropriate where, relatively speaking, the separator has a maximum diameter which is relatively large compared with the diameter of the underflow outlet. However where this ratio is relatively smaller, such as less than 3 it may be preferable to place greater restrictions on the relative values of the constants a and The following may then be appropriate: 0 00 00 0 *o 04 1I 0 0 4. 4.

substantial magnitudes of vector U, rD being the length of the outer profile of the inlet tract, viewed axially of the separating chamber, /3 D/d 3 r 2. and 0.35 2.

Rere, d represents the underflow outlet diameter corresponding to diameter d 3 in Figure 1.

Referring now to Figure 7, in one construction in accordance with the invention, the angle P measured about the axis of the separator between the points "C" 0 and was 86*. Tne inne; profile 84 was terminated o 10 by a curved portion 84a co-joining with circumference o 0 86, this portion had a curvature of approximately o o o 0.5mm and located some 1100 around the axis of the o "o separator from the point In this instance, it o was found that the following mathematical relationship was appropriate for describing the profiles 82, 84: r 0 0.5 D 0.0143 D Z0 1 4 0.0057 D Z 1.8 oft* 0o0o 2.8 0.00157 D Z 0.00286 D Z 0 0 2 3 o r i 0.5 D 0.0714 D Z i 0.00714 D Z 0.0143 D Z 4 0.00714 D .D i where r is the distance from the axis of the separator to any particular point on the outer profile 82, r i is the distance from the axis of the separator to any particular point on the inner profile 84, Z 0 is the angle, reckoned from the line 91 joining th& axis L LA4

TE\

j iof the separator and the point in a clockwise direction around the axis of the separator to any point on the outer profile 82 and Z i is the angle, reckoned from the line 10Q in a clockwise direction to any particular point on the inner profile 84. These equations describing the prc5iles 82, 84 generally may prevail for angles Z 0 i in the range 0 5 0 S, o- or more preferably in the range *0 3.

S2 I 10 z 3 o° «The tract 80 may have a rectangular transverse o o00o cross section such as having longer sides extending para3 '1 to the axis of the separator and of length W and norter sides contained in planes normal to the axis of the separator and of length t. In this case for a single inlet tract 80 the following relationsnips may prevail.

t x W A 00 i, and o00 0 0 0 D/35 t 0 a S Generally, W will be greater than t.

Figure 8 shows a further modification of the separator in accordance with the invention where the inlet tract 80 is shown as extending with its mean flow path 93 for liquid flowing therein as being at an angle to the axis 95 of the separator rather than being normal thereto as illustrated in Figure 1. In this case the axis 93 of tract 80 makes an angle to axis in the range 4 19rr 9 36

I

The following statement is a full description ot tnzs invenlluu including the best method of perforing it known to us -1if 00 o00 a o00 o0 00 o 00 0 0 0 OO0 0 o0 D 00 0 0 00 00 00 0 0o 00 00 0 0 0 o0 0 0000 o o 0 S lY 00 0 o o Q0 0 0 0 000 O0 0 6 4 Gc 11 Where the tract is of rectangular cross section it is preferred that it be of such rectangular cross section at least over a length qD where q is less than a.

In this specification, all angles are to be S understood as being expressed in radians unless otherwise specified.

The described separator inlet configuration may readily be employed where more than one tract 80 is provided. In this case, the total cross sectional 10 area of all the tracts measured radially of the separator through respective points should equal the area Ai such as where appearing in a formulae t x W A i should be replaced by Ai/n where n is the number of tracts 80. It should also be noted that not all of the tracts need be identical. In particular, where they are not identical the total area A i is related to the lengths and widths of the feed tracts at the relevant cross sections as follows: Zt n x W A, where t and W are the width n in n 20 and length respectively of the n th tract.

The described- separator has been found to provide excellent operating characteristics when separating smaller quantities of oil form larger quantities of water.

Figure 3 shows a modification of the separator of Figure 1. Here, the end wall 50 of the separating chamber portion 14, adjacent overflow outlet 25, is formed of concave form. In Figure 4, the end wall is shown in a further modification as exhibiting a convex form when viewed in axial section. Figure shows a still further modification where the overflow i 1 at an axially positioned underflow outlet at the end of the separating chamber opposite said one end, 1( 12 inlet 25 is formed from a pipe 27 having a portion 27a which extends through wall 50 (in this case, shown as being linear in axial section) and into the separating chamber 14 a short distance.

While forming the inlet means of the separator with the described configurations permits only a single inlet to be employed, the described configurations may be advantageously employed even where more than one inlet is provided.

The described arrangement has been advanced merely by way of explanation and many modifications 0 o o° may be made thereto without departing from the spirit 0 Go o o and scope of the invention as defined in the appended ,oo claims, o000 0 00 0 D0 000 o o o& 0 o Stt0

Claims

1. A cyclone separator for separating a, denserN component of a liquid mixture Irom a I~ss *dense component thereof, said separator being of a kind having an axially extending separting chamber ha ving towards one end inlet means for -admission of the *0 4 0 o 884 0 U 4 8 4 6 U 0

4. o~ 04 4~, 0 4 0 6 48 o 0 0 04 4 00 o 0 0 08 0 0 088 i tUi O O 4 14 mixture with a tangential flow component, the separating chamber having an axially positioned overflow outlet adjacent said one end and said separating chamber of generally tapered form with a relatively larger cross-sectional size at said one end and a relatively small cross sectional size at an axially positioned underflow outlet at the end of the separating chamber b posite said one end, wherein in use the denser component is directed to the underflow outlet in a fashion such as to encompass an inner axially positioned core of the less dense component which is subjected at least over a substantial part of o its length to a pressure differential causing it to flow to the overflow outlet, said inlet means being defined by a portion of the separating chamber and at least one inlet tract communicating with said portion, said portion being that portion of the separating chamber which is at the same lengthwise postion as the or each inlet tract, wherein the or each inlet tract oo.. presents inner and outer profiles, when viewed axially of the separator, said outer profile extending from a S first location at which it meets the circumference of 04 said portion of the separating chamber and at least the inward projection of said inner profile extending from a second location at which the inner profile or i, its said projection meets said circumference, said I profiles being charatorircd in that: a first vector T describing the location of any particular point on said outer profile and contained in a plane normal to said axis, and having its origin at said first location, is such that as the magnitude of the vector T increases, an angle e between the vector T and that tangent to said circumference which /AL t A ,O 0I r 1 1 passes through said first location never decreases and never becomes less than zero for all magnitudes of vector T less than n a second vector U, describing the location of any particular point on the inner profile and having its point of origin at said second location is such that as the magnitude of vector U increases, an angle between vector U and that tangent to said circum- ference which passes through said second location never decreases and never becomes less than zero for all magnitudes of vector U less than aD at least for o substantial magnitudes of Vector U, o D being the length of the outer profile of the inlet tract, viewed axially of the separating chamber, o o D being the diameter of said portion of the separating chamber o(D being the length of the inner profile of the inlet tract viewed axially of the separating chamber, rD being measured from a first location at which the o outer profile meets the circumference of its portion a 4 Si I L Ct t 16 of the separating chamber and ceD being measured from a second locat.cn: at which at least an inward pro- jection of the inn,-r profile meets said circumference. 2. A cyclone separator as claimed in claim 1 wherein: 0.04 4 Ai/ TD 2 0.1 where A i is the cross-sectional area of said tract, or the combined cross-sectional area of all said tracts, if there is more than one tract, the or each cross-sectional area being measured in a plane substantially perpendicular to tract inlet flow and intersecting *o the point of teimination of said inner profile. 0 4 t 1 44 4 44 3. A cyclone separator as claimed in claim or claim 2 characterised in that C and 0.35 a<2 A cyclone separator as claimed in any one of claims 1 to 3 wherein the or each inlet tract is of rectangular cros, section over at least a length qD for q Q< the cross section having a length Wn and a width t S where St n x Wn A i and n X W t D/8 Ui stantially tangential at the point of meeting the 'V ___Now" 17 where W is the length of the cross section of the th tract and tr is the width of the nth tract. A cyclone separator as claimed in claim 4 wherein the sides of the or each cross section of length W are aligned generally in the axial direction of the separator and those of. width t are aligned ger. MlIy normally to the axis of the separator.

6. A cyclone separator as claimed in claim where W t.

7. A cyclone separator as claimed in any one of claims 1 to 6 wherein the or each tract extends at a respective angle to the axis of the separator, when viewed normally of said axis, wherein the respective angle between said axis and the mean inlet flow direction for liquid mixture when admitted through a respective inlet tract, at the point where the mean flow path intersects the said respective tract cross-section at which the area A i is measured, is o ol~ 0 0 0 o* ooo 0 0o 000021 9 1 p 191r 36 where the angle P is defined such that for values thereof less than 900 the liquid flow into the separating chamber in use, along said flow path, has a motional component which is directed in the direc- tion from the larger diameter to the smaller diameter end oi the separating chamber. separating chamber. Thus, a is the ratio !C D where G is the length of the inner profile and D is NEW W

8. A cyclonie separator as claimed in any one of claims 1 to 7, wherein an end wall of the separating chamrber, thmugh whi 'ch said overflowv outlet cmmunicates with the separating chatier, is fonred of curved configurwaticnt. :0 0 000 009 0 00 0t 0 0 00 0 0 00 0 0 00 60 C0 00 000 00 0 0 0a 000 0 00 0 0 0 0 00 00 006 I !j i t I: II 19

9. A cyclone separator as claimed in claim 8 wherein said end wall is concave. A cyclone separator as claimed in claim 8 wherein said end wall is convex.

11. A cyclone separator'as claimed in any one of claims,'. 1 to 10, wherein the overflow outlet is in the form of a duct which extends through an end wall of the separating ch mber and projects into the separating c; amber.

12. A cyclone separator as claimed in any one of claims 1 to 11 wherein the outer profile of the or each inlet tract is of involute form.

13. A cyclone separator as claimed in any one of claims 1 to 12, wherein the inner profile of the or each inlet tract is of involute form.

14. A cyclone separator as claimed in any one of claims 1 to 13 having a single inlet tract. o 00 o 0 0 0 o 0a o o os o a o 0 0 r 0 oo 6 a 6 *o a O 44« t I 0 1 A cyclone separator as claimed in any preceding claim characterised in that said outer profile is substantially defined by the following mathematical relationships r 0 *0.5 D 0.0143 D 014 0.0057 D 1 8 0.00157 D S +0.00286 D 4 where ro is the distance from the axis of the separator to any particular point on the outer profile, reckoned S from an imaginary line joining the axis of the .o separator and the point where the outer profile o:0 meets said circumference, and Z o is the angle, reckoned from an imaginary line joining theaxi 0 0 *of the separator to the point where the outer profile o meets said circumference, to a point on the outer profile.

16. A cyclone separator as claimed in any one of claims 1 to 15 characterised in that said inner profile is substantially defined by the following mathematical relationships r L 0.5 D 0.0714 D 3L2 0.00714 D 3 3 0.0143 D 4 0.00714 D where ri is the distance from the axis from the separator to any particular point on the inner profile and Z i is the angle, reckoned from an imaginary line joining the axis of the separator to the point where at least the projection of the inner profile meets said circumference, to a point on the inner f.1 profile. i 21

17. A cyclone separator as claimed in claim 15 or claim 16 characterised in that said mathematical relationship prevails over angles Z o in the range 0* Z o 150*.

18. A cyclone separator as claimed in claim J5, claim 16 or claim 17 characterised in that said mathematical relationship prevails over angle Zj in thoe range S0 Zi

19. A cyclone separator as claimed in claim 15, claim 16 or c)aim 17 characterised in that said mathematical relationship prevails over angle Z i in the range 24' Zi oo. 20. A cyclone separator as claimed in any one of the preceding claims characterised in that said separating chamber comprises first, second and third portions.arranged in that order with said overflow outlet being provided axially at said first portion and said or each said inlet tract extending into the separating chamber at said first portion, said overflow outlet being provided at an end of said third portion o remote from said first portion and wherein 4 12/d 4q r. 0.04 A/ d 2 0.10 0.1 d/d2 0.25 d I> d 2 a 2 d 3 ALI where Ai is the total cross sectional area of the inlet tract, or all of the inlet tracts, at the 6 I i n,'.Ja V-1 a ~i 22 c..rcumfer.ence of the first portion, do is the diameter of the overflow outlet, dl is the diameter of said first portion# d 2 is the diameter of the second portion at the end thereof closest the first portion 12 is the l-ength of the second portion and d 3 is the diameter of the third portion.

21. A cyclone separator as claimed in any one of claims, 1 to 19 characterised in that said -separating chamber comprises first, second and third portions 'arranged in that order with said overflow outlet being provided axially at said first portion and said or each said inlet tract extending into the separating chamber at said first portion, said overflow outlet being provided at an and of' said third portion o a04 remote from said first. portion and wherein 1 1 2 /d 2 4C 0.04 4Aj/1 d 1 2 0.10 d a/M 2 0.1l 9* 2 d 1 d 2 ~2 3 where Ai is the total cross sectional area of the inlet tract, or all of the inlet tracts, at the circumfejrence of the first portion, do is the diameter of the overflow outlet, dl is the diameter of said first portion, d 2 is the diameter of the second portion at the end thereof closest the first portion 12 is the lengith of the second portion and d 3 is the diameter of the third portion. 23

22. A cyclone separator as claimed in claim 1 substantially as described herein with reference to the drawings. DATED this 27th day of June, 1990. CONOCO SPECIALTY PRODUCTS INC By its Patent Attorneys 'TAVIES COLLISON