Centrifuges sludge separators

In continuous systems, preheated crude oil (80°C) and water are metered into an in-dwell pipeline agitator, or a large agitated tank, and held only for a short period. In both systems, the oil is then pumped to a centrifuge for separation of the lecithin sludge from the oil (33, 118, 125-126). Water with a low concentration of calcium and magnesium is preferred (115). 

Practical operation of a sludge separator, of course, requires that the solids be heavier than the liquid and not be resuspended by the action of the conveyor. A modification known as an axial-flow conveyor centrifuge (described later) is more effective in separating fine light solids than the full-scroll centrifuge shown in Fig. 30.44. Even so, the liquid effluent from these machines is usually not completely free from solids and may require subsequent clarification. Within these restrictions sludge separators solve a wide variety of problems. They separate fine particles from liquids, dewater and wash free-draining crystals, and are often used as classifiers. 

W W-F Leung. Torque requirement for high-solids centrifugal sludge dewatering. Filtration+Separation 35 (1998) 883 (Figure lb)... 

Centrifugal clarifiers are intended to clean oil free of suspended solids and so have no separate water outlet holes. Feed is from the outer edge of the disc stack, into the zone of maximum centrifugal force, with sludge separating outwards to the bowl wall. 

Less stable parts of the sludge can be treated by holding in tanks for extended periods of time to allow the weaker emulsion to break and separate a clean product. The mote stable sludges can be broken by mechanical action in filters or centrifuges, by recycle to the furnace for redistillation, or by redistillation in auxiliary units. Chemical attack via oxidation or complexing agents that break the emulsion has also been employed. 

Centrifugation is a well-established liquid-solid separation process popular in commercial and municipal waste treatment facilities. It is usually used to reduce slurry and sludge volumes and to increase the solids concentration in these waste streams. It is a technically and economically competitive process and is commonly used on waste sludges produced from water pollution control systems and on biological sludges produced in industry and municipal treatment facilities. 

This is a liquid/solid separation process using centrifugal force. The moisture of the sludge can be reduced to 65-70%. 

The SAREX process is a trailer/skid-mounted, modular system designed for on-site, in-line separation and resource recovery of oily waste sludges and contaminated soils. This process provides dewatering and thermal desorption to maximize the recovery of oil while obtaining substantial reduction in volume and contaminant concentrations. The SAREX process includes the MX-1500 centrifuge, the MX-2000 low-temperature thermal dryer, and the MX-2500 medium-temperature thermal desorber. The MX-1500 centrifuge is used to separate the solids from the... 

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