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16 Part I Liquid Drilling Systems

Figure 1.18 A mud cleaner. (Courtesy of TSC.)

The hydrocyclone (Figure 1.19) has a conical-shaped portion in which
most of the settling takes place and a cylindrical feed chamber at the large
end of the conical section. At the apex of the conical section is the
underflow opening for the solids discharge. In operation, the underflow
opening is usually at the bottom. Near the top end of the feed chamber,
the inlet nozzle enters tangentially to the inside circumference and on a
plane perpendicular to the top-to-bottom central axis of the hydro-
cyclone. The hydrocyclone obtains its centrifugal field from the tangential
velocity of the slurry entering the feed chamber.
An axial velocity component is created by the axial thrust of the feed
stream leaving the blind annular space of the feed chamber. The result
is a downward-spiraling velocity labeled S in Figure 1.19, in which
T and A represent the tangential and the axial velocity components,
respectively. A hollow cylinder, called the vortex finder, extends axially