Good solids-removal equipment operation, including that of shale shakers, helps prevent these problems.
Electric Motors For Decanter Centrifuge
Most Decanter Centrifuges use the same NEMA design B explosion-proof motors used for centrifugal pumps: either 1500 rpm at 50 Hz or 1800 rpm at 60 Hz. Decanter Centrifuges may draw up to seven times the full-load current for approximately 15 seconds at startup. It is considered good practice to limit centrifuge startups to two starts per hour to protect the motor because the current draw closely approaches the limit.
When mechanical separation equipment is used to remove suspended solids from liquids, capture determinations provide a simple means of evaluating its performance. Capture is defined as the fraction of incoming suspended solids that report to the discarded stream.
Weighted NAFs present a special problem because of the cost of the base fluid, which can exceed $200/bbl. The objections to series centrifugation raised in the previous section are equally valid for these fluids. Fortunately, NAFs are more solids tolerant than water-based fluids. However, when NAFs are used long enough, ultra-fines and colloids can accumulate to problem levels and force difficult choices.