Wash Efficiency

Cold wash, distributed over the wax cake by drip pipes or sprays, will displace the cake liquids, reducing the Oil in Wax and increasing the yield. This occurs in two steps. The first step is a piston displacement where the wash liquid pushes out the cake liquids. In the second step, oil from within the wax crystal diffuses into the low oil concentration wash liquid. The theoretical reduction in oil content may be predicted by the Butler equation . 

The wash efficiency is defined as the actual oil in wax obtained for a given amount of wash applied relative to that predicted by the Butler curve. Efficiencies may be less than 100%. This may result from  

Poor distribution along the drip pipe, out of level on older designs 

Area of excessively fouled filter cloth may occur when drying is practiced 

Cracked filter cake, solvent flows through crack instead of cake Wash rate exceeding wash acceptance 

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Control philosophies applied to continuous countercurrent decantation (CCD) thick eners are similar to those used for thickeners in other applications, but have emphasis on maintaining the CCD circuit in balance. It is important to prevent any one of the thickeners from pumping out too fast, otherwise an upstream unit could be stai ved of wash liquor while at the same too much underflow could be placed in a downstream unit too quickly, disrupting the operation of both units as well as reducing the circuit washing efficiency. Several control configurations have Been attempted, and the more successful schemes... 

Cake Washing Wash efficiency data are most conveniently represented by a semilog plot of percent remaining B as a function of wash ratio N as shown in Fig. 18-103. Percent remaining refers to that portion of the solute in the dewatered but unwashed cake which is left in the washed and dewatered cake. Since a cake-washing operation... 

By cooling and stirring as described, the product is obtained in a finely divided form, which can be removed from the flask easily and also can be washed efficiently. 

On the rayon washing system, a minimum water-to-fiber ratio for the batt weights used was about 55/1. The Mississippi cotton was much more difficult to wet out than either the California or Texas cottons. The Mississippi cotton, compared with the California and Texas cotton, was a low noncellulose cotton and had a more hydrophobic surface. Thus, the wettability and, consequently, the washing efficiency of cotton is related to and dependent upon the surface characteristics of the cotton. Configuration of the materials on the fiber surface are related to variety, area of growth, environmental conditions, method and time of harvest, storage conditions, and other factors. 

Werter RC et al Polychlorinated biphenyls (PCBs) Dermal absorption, systemic elimination, and dermal wash efficiency. J Toxicol Environ Health 12 511-519, 1983... 

Since the mid-60s, the use of enzymes in detergents has been the largest of all enzyme applications. Over half of all detergents presently available contain enzymes, in particular proteases, amylases, lipases and ceUulases. Besides improved washing efficiency, the use of enzymes allows lower temperatures and shorter wash periods (of agitation) to be employed, often after a preliminary period of soaking. Further in this chapter (section 3.3) the detergent enzymes are worked out in more detail. 

Many improvements have been made since Maffei s system. First of all, the washing chamber needs to be pressurized to maintain the CO2 in the liquid state, otherwise the CO2 must be very cold to remain liquid. To enhance the washing efficiency, garments have to be agitated to remove solid stains and particles which are not soluble in CO2. 

Figure 11.3. Laboratory test data with a vacuum leaf filter, (a) Rates of formation of dry cake and filtrate, (b) Washing efficiency, (c) Air flow rate vs. drying time, (d) Correlation of moisture content with the air rate, pressure difference AP, cake amount W Ib/sqft, drying time 6d min and viscosity of liquid Dahlstrom and Silverblatt, 1977).

The free amino acid (S,S-form) was prepared by treatment of an aqueous solution of the hydrochloride with saturated sodium acetate. The product was filtered, washed efficiently with cold water and recrystallized from ethyl acetate melting point 149-151°C [a]D23 = +29.7°. 

The very nature of process development necessitates the contributions of all members of a typical development team. Thus, reaction engineers determine reaction kinetics and select the best reactor type, while filtration experts measure the filter cake resistance and washing efficiency. To reduce development time, it is crucial that all of these activities be performed in a coordinated manner. Proper workflow automates such a development process, in whole or part, during which documents, information, or tasks are passed from one participant to another for action, according to a set of procedural rules. 

Figure 3.8 shows the dynamic surface tension of a pure anionic and a non-ionic surfactant dependent on the absorption time after the creation of new surface for different concentrations [9]. For both surfactants, the time dependence of the surface tension is greatly reduced when the concentration increases and this effect is especially pronounced when the critical micelle concentration is reached. The reason for this dependence is the diffusion of surfactant molecules and micellar aggregates to the surface which influences the surface tension on newly generated surfaces. This dynamic effect of surface tension can probably be attributed to the observation that an optimum of the washing efficiency usually occurs well above the critical micelle concentration. The effect is an important factor for cleaning and institutional washing where short process times are common. 

We also investigated the tip-wash efficiency using two types of carryover test experiments the first experiment uses source plates filled with pure DMSO and intervening source plates filled with fluorescein solution in DMSO. The measured fluorescein carryover from the source plate of the previous replication cycle to the target plates of the subsequent replication cycle was found to be less than 0.004% (<4 X 10 ). In the second test experiment, six different compound solutions in DMSO were processed on the plate-replication system. The carryover of the compounds from the previous source plate was determined in the target plates of the subsequent replication cycle using LC/MS/MS analytics. The measured compound carryover from the source plate of the previous replication cycle to the target plates of the subsequent replication cycle was always smaller than 0.008% (<8 X 10 ).T... 

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