BAKER HUGHES - Drilling Fluids Reference Manual

MECHANICAL SOLIDS CONTROL
RMS Centrifuge
There is an alternative to the use of a decanting-bowl centrifuge for barite recovery. It is the RMSnot
make
type centrifuge. This type unit is particularly applicable where rig-up restrictions will not allow use
of a decanting-type unit. Although this unit is capable of handling more fluid, it tends to
as fine a cut on the barite as a decanting unit does. Also, because the returned phase is wetter, it
will contain a higher percentage of undesirable solids.
General Operation of the RMS Centrifuge
The separation chamber of the centrifuge consists of a stationary case and a perforated cylinder
which revolves concentrically within the case. The combined discharge from two metering pumps
supplies a fluid/water mixture which is introduced to the separator chamber annulus between the
stationary case and the rotating perforated cylinder. As the diluted mixture enters the case, the
rotation exposes all solid particles to centrifugal force, moving them away from the rotor and
toward the case wall. The condensed phase moves through the case along the walls and exits at the
underflow port. The lighter phase moves toward the center of the perforated cylinder and exits
through the overflow tube.
Figure 10-8 is a schematic of an RMS separation chamber.
Closed-Loop Systems
Figure 10 - 8 RMS Separation Chamber
Closed-loop systems describe any operation where no reserve pit is utilized. This is commonly due
to environmental restrictions, but may be caused by space limitations, cost to build and close the
pit, or expense of the liquid phase. Depending on the economics of disposing of excess fluid and
cuttings, the system may consist of no additional equipment on the rig to a full-blown system that
includes all the mechanical equipment necessary to achieve maximum solids removal and a
dewatering operation to finish the removal of all excess solids.
The function of a closed-loop operation, where disposal costs are high, is to minimize the haul-off
by condensing the discards to the minimum volume. For instance, if 9 lb m /gal fluid is hauled off,
BAKER HUGHES DRILLING FLUIDS
REVISION 2006 10-18
REFERENCE MANUAL