Decanter centrifuge installation
The decanter centrifuge suction should be in the compartment receiving the discharge from the desilters and mud cleaners, and the returned stream should be directed to the next compartment downstream.
Installation should permit the discharge of either the underflow (as is usual when processing unweighted fluids) or the overflow, as in traditional centrifuging. In either case, the recovered stream should be returned to a well-stirred area of the receiving compartment. This is particularly important in the case of recovered underflow, which usually contains too little liquid to permit it to flow and can be difficult to remix into the drilling fluid. If the underflow is returned to the mud, or discarded via a chute, the chute must be at an angle of no less than 42 with the horizontal. It is particularly important that the underflow be returned to a compartment that normally has a high fluid level and is well agitated.
Decanter centrifuge applications
The two primary reasons for the use of decanter centrifuges with drilling fluids
(1) the selective separation of colloidal and ultra-fine solids from weighted fluids to improve their flow properties and
(2) the removal of fine solids from unweighted fluids.