Compression filters

Continuous Compression Filters. The variable chamber principle appHed to batch filtration, as described before, can also be used continuously in belt presses and screw presses. 

In compressible filter cakes, the porosity varies from a minimum next to the filter septum to a maximum at the cake surface. How could you include such a variation within the context of a simulation program Remember that as the porosity changes, the local fluid velocity will also change as a result of... 

The specific resistances obtained are independent of applied load, suspension concentration and membrane type, as expected for non-compressible filter cakes. Tests with uniform latex particles have given permeabilities in very good agreement with Equation 2, using a value of 5 for the Carman-Kozeny constant. 

Batch carbon dioxide foaming, 24 21 Batch chromatography, for enantiomeric purification of pharmaceutical intermediate, l 685t Batch compartment dryers, 9 118-119 Batch compression filters, mechanical, 11 370-373... 

Compression drug coatings, 78 707-708 Compression filters, continuous, 77 379-381... 

Continuous cellulosic fibers, 20 557 Continuous compression filters, 77 379-381 Continuous conveyors, 9 119 Continuous cooling, in austenite transformation, 23 282-283 Continuous-cooling transformation (CCT) diagrams, 77 16 23 280 Continuous copper-drossing process, 74 745-747... 

Figure 7.3. Flow through a compressible filter cake...

R.J. Wakeman, A numerical integration of the differential equations describing the formation of and flow in compressible filter cakes. Trans. Inst. Chem. Eng. 56, 258-265 (1978). 

Continuous compression filters include hell presses and screw presses,... 

Shake vigorously a mixture of 105 g (1.0 mol) of purified benzaldehyde (Expt 6.133), 38.8 g (0.2 mol) of methyl a-D-glucopyranoside (1) and 29.5 g of freshly fused and powdered anhydrous zinc chloride (0.22 mol) in a conical flask in a mechanical shaker for about 10 hours, until a clear solution is obtained. Allow the solution to stand at room temperature for a further period of 18 hours and then pour it into 700 ml of iced water (2). Stir the mixture vigorously, filter off the solid which separates and wash the compressed filter cake with light petroleum (b.p. 40-60 °C) to remove as much of the unreacted benzaldehyde as possible. Remove the solid from the Buchner funnel, stir or shake it vigorously with a solution of 12g of sodium metabisulphite in 120 ml of water, filter and wash the filter cake with water. Crystallise the solid from hot water, or after drying in a vacuum desiccator, from a mixture of chloroform and ether. The pure product has m.p. 165°C, [oc]d° + 112° (c0.5 in CHC13), the yield is 29 g (52%). 

The addition of half a Whatman filtration accelerator (or a little filter paper pulp) assists filtration the precipitate must be washed thoroughly with hot water. The filtration accelerator consists of compressed filter paper which disintegrates on boiling it increases the speed of filtration by retaining part of the precipitate and thus preventing the clogging of the pores of the filter paper. 

Compressibility, filter cake, 310, 311,316 cell measurements, 314 calculation example, 314... 

Sterilization. This is necessary to prevent the growth of foreign microorganisms. Air is sterilized adequately by the heat of compression. Filters at the inlet remove oil and any microbes that may be present, and filters at the air outlet prevent backflow of foreign microorganisms. The inoculum is prepared under sterile conditions in the laboratory. The substrate is sterilized in an external vessel by holding it at 120°C or so for 1 hr or so. 

The pressure applied on the cake in a belt press operation is low compared to that in other compression filters. The applied pressures are commonly expressed in pli (pound per linear inch) which is not straightforward in translating to a commonly recognized pressure unit. As a rough comparison, the pressures used in belt presses are around 10 to 20 psi. This pressure can be controlled by the belt and roller tension but seldom is adjusted by operators in the field. 

Tiller, F.M. Horng, L.L. Hydraulic deliquoring of compressible filter cakes. Part I. Reverse flow in Alter presses. AIChE J. 1983,29, 297-305. 

FIGURE 22.27 Variation of hydraulic and effective pressures in a compressible filter cake. 

Batch, semi-batch vacuum filters Continuous vacuum filters Batch, semi-batch pressure filters Continuous pressure filters Compression filters Filtering centrifuges Precoat filters... 

---