Dewaxing centrifuge

Centrifugal expanders Centrifugalpumps Centrifugal separation Centrifugal sucrose Centnfugation Centrifuge dewaxing... 

Another method of separating petrolatum from residua is by centrifuge dewaxing. In this process, the reduced cmde oil is dissolved in naphtha and chilled to —18° C or lower, which causes the wax to separate. The mixture is then fed to a battery of centrifuges where the wax is separated from the Hquid. However, the centrifuge method has been largely displaced by solvent dewaxing methods as well as more modem methods of wax removal. Similar use is... 

One method used to assure clear oil is to add a polish filtration step after the centrifuge dewaxing operation, as shown in Figure 9c With this system, a shp stream of oil is cooled and analyzed through a highly sensitive turbidity meter immediately after the deodorizer. When a haze is detected, the flow of oil is diverted through a chiller, filter aid added, and the mixture sent to a crystallizing tank. After... 

The process is reported capable of dewaxing any wax-bearing stock, either raw or after selective solvent refining, and waxes with a relatively low oil content may be obtained, by a two-stage operation in which the wax from the primary stage is rerun after further dilution with cold solvent on a second battery of centrifuges. 

The dewaxed oil and wax phases discharged from the centrifuges are transferred through heat exchange equipment to individual solvent recovery units for continuous recovery of solvent. 

Twenty-five years ago the dewaxing processes available to the refiner of lubricating oils were the cold pressing method applicable only to low viscosity distillates and the cold settling and centrifuge methods applicable to certain residual oils. A vast amount of... 

Solvent dewaxing a process for removing wax from oils by means of solvents usually by chilling a mixture of solvent and waxy oil, filtration or by centrifuging the wax which precipitates, and solvent recovery. 

Dewaxing is frequently referred to as winterization. The process in which, for example, up to 0.4% of high-melting-point (76/77 °C) waxes are removed from sunflower oil is similar to those already described. Crystallization is carried out to 6-8 °C but in order to improve separation the temperature is raised to 15-18 °C before filtration or centrifugation (Kehse, 1979). A filter aid is always used to assist filtration in the dry process. 

Centrifuging. Although the centrifuge process (Fig. 12-3) was the exclusive means of dewaxing bright stock for many years, it" is rapidly being displaced by solvent processes. Percolated or acid-treated and... 

Many schemes have been applied to improve centrifu g properties. In processing very waxy stocks and some overhead stocks, it is necessary to recirculate some of the dewaxed oil. Other stocks can be successfully centrifuged by recirculating some of the petrolatum, and in rare cases it has been necessary to add-dark-colored material to the stock. In one plant, evaporation losses are minimized by the use of hexane instead of naphtha and by the use of a completely enclosed circulating system. 

The use of two dewaxing methods, i.e., pressing and centrifuging, has been a source of great expense to refiners. Almost all new plants employ solvents (Table 11-1). The Weir filter-aid process (patented in 1924) was the first commercial solvent dewaxing process. It involved the filtration of chilled naphtha oil solution mixed with about 15 per cent of filter aid (fuller s or diatomaceous earth). Modem solvent processes employ special solvents, such as acetone-benzene, trichlorethylene, ethylene dichloride-benzol (Barisol), smd particularly propane and methyl ethyl ketone-benzol. ... 

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