Applications decanter centrifuge

Table 8.2 Some applications of decanter centrifuge operation...

At the other end of the application scale, the conventional decanter centrifuge is now also used in and made specifically for processing of drilling mud ( mud technology ) -... 

The solid-bowl scroll-discharge centrifuge — now almost universally known as the decanter centrifuge — has, indeed, become the workhorse of a wide range of liquid/solid separation activities. Its application to the dewatering of waste sludges has made it a most valuable tool in combating environmental pollution. This has made the decanter a well-known and widely appreciated piece of equipment. 

The decanter centrifuge Is a major item of processing equipment in many industrial applications, and this chapter illustrates this range of use. The driving forces in the decanter marketplace result almost entirely from the needs of these industrial applications, so their importance to a handbook on the decanter is easy to see. The decanter has no place, however, in domestic, institutional or commercial (business) applications, which are covered by separation equipment of quite different kinds. 

In decanter applications, the higher molecular weight polymers predominate. Nevertheless, occasionally some lower molecular weight polymers are found very effective when used on some decanter centrifuges. Cross-linked polymers are finding frequent use on decanters, with both municipal and, particularly, industrial effluents. 

The decanter centrifuge is an important processing tool, but is by no means cheap, so the decision to invest in a new decanter is one that has to be taken with care. The market is characterised by the presence in it of a few large suppliers, with many years of experience and with wide ranges of types of decanter available. There is then a group of smaller, general suppliers, plus a handful of niche market suppliers (mostly to olive oil production and similar applications). There is certainly enough experience available in the market place, to enable any potential purchaser to obtain satisfactory quotations for a new machine from a number of competitive suppliers. 

Most industrial liquid-liquid applications fall into the category of being more concentrated systems. We identify more concentrated systems as 4) > 0.20 by volume fraction of dispersed phase. Industrial examples include suspension and emulsion polymerization, extraction, and separations, including decantation, centrifugation, and electrostatic precipitation. Because practice is as much an art as a science, much of the industrial experience on concentrated systems is proprietary and not published, contrasting the vast amount of academic work published for dilute and clean systems. 

The filter press has been very successfully applied to the dewatering of a range of sludges, especially those from water and waste treatment processes, and competes strongly in this application with the vacuum belt filter and the decanter centrifuge. 

Decanter centrifuges, for process applications, are typically solid bowl scroll-discharge machines, capable of continuous sohd and centrate discharge. They are ideally suited to handling high feed solids concentrations and delivering dry solid products. They are generally able to convey the soft solids often encountered in the pharmaceutical and fermentation industries. 

The decanting centrifuge is an effective oil treatment separator, processing mixtures with larger size impurities and higher feed concentrations. In most applications of the decanter it is used to separate a hquid from a solid, a job it does very well. 

In some circumstances, separation of solid from a liquid is better achieved by use of a centrifuge than by filtration, and a small, electrically driven centrifuge is a useful piece of equipment for an analytical laboratory. It may be employed for removing the mother liquor from recrystallised salts, for collecting difficultly filterable precipitates, and for the washing of certain precipitates by decantation. It is particularly useful when small quantities of solids are involved centrifuging, followed by decantation and re-centrifuging, avoids transference losses and yields the solid phase in a compact form. Another valuable application is for the separation of two immiscible phases. 

Pharmaceutical Removal of suspended matter is a frequent application for MF. Processes may be either clarification, in which the main product is a clarified liquid, or solids recovery. Separating cells or their fragments from broth is the most common application. Clarification of the broth in preparation for product recovery is the usual objective, but the primary goal may be recovery of cells. Cross-flow microfiltration competes w l with centrifugation, conventional filtration by rotary vacuum filter or filter press and decantation. MF delivers a cleaner permeate, an uncontaminated, concentrated cell product... 

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