Containment loss filters

Various types of filters are used to remove fines. Paper filters are not the best. They cause high oil loss and the hot oil is exposed to air for long. The fryer system generally contains a filter to remove the coarse material from the oil. Sometimes, this is augmented with a finer filter that removes the smaller particles from the fryer oil. In many applications, one needs to use a combination of a motorized and a centrifugal filter (or a rotary drum filter see Figure 18). 

Zero-loss filtering Both BF TEM images and diffraction patterns contain inelastically scattered electrons. The number of inelastic electrons increases with the increase of specimen thickness and they cause a diffuse background. Using a narrow sUt width (for example, 5 eV) at the ZLP, this filters out the majority of inelastic electrons and thus significantly improves the image contrast. 

General Considerations. With liquids and solutions the most serious losses are due to (a) transference from spherical flasks and difficulties of drainage, (b) retention by filter-papers, (c) absorption by large corks. As containers for small quantities of liquids it is therefore often convenient to use pear-shaped flasks A and conical test-tubes or centrifuge-tubes B (Fig. 29). (In this and subsequent figures, approximate dimensions are given to indicate a convenient size.)... 

The sweet water from continuous and batch autoclave processes for splitting fats contains tittle or no mineral acids and salts and requires very tittle in the way of purification, as compared to spent lye from kettle soapmaking (9). The sweet water should be processed promptly after splitting to avoid degradation and loss of glycerol by fermentation. Any fatty acids that rise to the top of the sweet water are skimmed. A small amount of alkali is added to precipitate the dissolved fatty acids and neutralize the liquor. The alkaline liquor is then filtered and evaporated to an 88% cmde glycerol. Sweet water from modem noncatalytic, continuous hydrolysis may be evaporated to ca 88% without chemical treatment. 

One of the basic mechanisms in fluid loss prevention is shown in Figure 2-1. The fluid contains suspended particles. These particles move with the lateral flow out of the drill hole into the porous formation. The porous formation acts like a sieve for the suspended particles. The particles therefore will be captured near the surface and accumulated as a filter-cake. 

Predictions on the effectiveness of a fluid loss additive formulation can be made on a laboratory scale by characterizing the properties of the filter-cake formed by appropriate experiments. Most of the fluids containing fluid loss additives are thixotropic. Therefore the apparent viscosity will change when a shear stress in a vertical direction is applied, as is very normal in a circulating drilling fluid. For this reason, the results from static filtering experiments are expected to be different in comparison with dynamic experiments. 

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