Cyclone separator

Claim 1

A cyclone separator comprising (a) an inlet portion having generally the form of a volume of revolution, and one or more inlet channels, (b) a vortex finder outlet coaxial with the inlet portion and projecting into the inlet portion, (c) a generally axially symmetrical converging separation portion adjacent to the inlet portion and on the opposite side from the vortex finder outlet, characterised by the fact that the following relationships (i)-(v) apply wherein d o is the minimum internal diameter of the vortex finder outlet within 3d 2 of the inlet plane or at its end if this is not within 3d 2 of the inlet plane, d 1 is the diameter of the cyclone in the inlet portion where the feed enters, neglecting any inlet channel, d 2 is the diameter of the cyclone where the inlet portion joins the separation portion, d 3 is the diameter of the cyclone where the separation portion ends, d ix is twice the radius at which flow enters the cyclone through the x th inlet, A ix is the cross-sectional area of the x th inlet, as hereinbefore defined, ##EQU6## and α is the half angle of convergence of the separation portion (2) as hereinbefore defined: (i) 8≦πd 2 d i /4A i ≦16 (ii) 1°≦α<3° (iii) 0.25<d o <0.65 (iv) 0.9d 1 >d 2 (v) 0.9d 2 >d 3 .