Wash Acceptance

Wash acceptance is the amount of wash that can be accepted through the wax cake before it begins to spill or run off the wax cake. The volume of filtrate collected as a fiuiction of time decreases in a square root relationship, for non-compressible wax cakes, until the end of the filtration step. At that point filtration is complete, the wax cake formation has stopped and the wash 

Wash Acceptance (Filtration Time = Wash Time, Incompressible Cake) 

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High filtration rates lead to high wash acceptance or lower filter speeds for increased dewaxed oil yields... 

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

Some plants will dedicate a significant portion of the filter area to drying and will block off sprays or drips in this area. The intent is to reduce the Oil in Wax to increase yield and possibly debottleneck wax recovery. An unintended consequence is that the vacuum that remains on in this section will pull the wax cake into the filter cloth, accelerating the filter fouling which will reduce wash acceptance and increase oil in wax. It will also require more frequent filter washing which will reduce plant throughput. These competing factors must be balanced by the manufacturer to achieve the optimum filter performance. 

In the 1970s, Solvay iatroduced an advanced TiCl catalyst with high activity and stereoregulahty (6). When this catalyst was utilized ia Hquid monomer processes, the level of atactic polymer was sufftciendy low so that its removal from the product was not required. Catalyst residues were also reduced so that simplified systems for post-reactor treatment were acceptable. Sumitomo has developed a Hquid monomer process, used by Exxon (United States), ia which polymer slurry is washed ia a countercurrent column with fresh monomer and alcohol to provide highly purified polymer (128). 

This resia was temporarily accepted, primarily because of its improved resistance to acid washes. However, the relatively high cost of the diamine precluded widespread commercial acceptance. 

To add surface area, the supports are uniformly coated with a slurry of gamma-alumina and recalcined under moderate conditions. The wash coat acts to accept the active metals, typically low levels of platinum and palladium, in a conventional impregnation process. In the United States in passenger car apphcations the spherical catalyst is used almost exclusively, and methods have been developed to replace the catalyst without removing the converter shell when vehicle inspection reveals that emission standards are not met. 

The effluent from the isolation wash belt is the principal wastewater stream from the polymerization process. It contains highly diluted acetic acid and a surfactant that is not biodegradable. The wastewater streams are sent to sewage treatment plants where BOD is reduced to acceptable levels. Alternative biodegradable surfactants have been reported in the Hterature (173). 

Pretreatment Chemicals Even though the suspended solids concentration of the slurry to be tested may be correct, it is frequently necessary to modify the sluriy in order to provide an acceptable filtration rate, washing rate, or final cake moisture content. The most common treatment, and one which may provide improvement in all three of these categories, is the addition of flocculating agents, either inorganic chemicals or natural or synthetic polymers. The main task at this point is to determine which is the most effective chemical and the quantity of chemical which should be used. 

The etched printed circuit boards are washed out with water to dilute the concentration of the contaminants on the board surface to an acceptable level. The extraction of copper from the effluent rinse water is essential for both environmental and economic reasons since decontaminated water is returned to the rinse vessel. 

The. statement goes on to acknowledge the contribution of the Reactor Safety Study (WASH-1400) to risk quantification but points out that safety goals were not the study objectives and that the uncertainties make it unsuitable for such a purpose. After pointing out that the death I f any individual is not "acceptable," it states two quantitative objectives ... 

Nuclear PSAs tend to accept a set of initiators such as the WASH-1400 set or the EPRI set and proceed with little introspection as to completeness of the set for a specific plant. A well-known omission is sabotage. In general, earthquake and fire is treated poorly tornado is usually not addressed nor are other aspects of adverse weather such as freezing and ice storms which may have common cause potential. The record has not been too good. After the Browns Ferry fire, it was claimed that such was addressed in WASH-1400. If so, attention was only brought after the fact. The TMI-2 sequence was not addressed in the PSAs to an extent that action was taken to prevent it. 

The need for heating, water washing, and the use of additives must be addressed when moving from the distillates toward the residuals. Fuel contaminants such as vanadium, sodium, potassium, and lead must be controlled to achieve acceptable turbine parts life. The same contaminants also can be introduced by the inlet air or by water/steam injection, and the combined effects from all sources must be considered. 

Polyvinyl acetate (PVA), acrylic and other polymer dispersions have been widely used as anti-dust treatments for concrete floors for many years. In general, the polymer dispersions have been similar to those used in the manufacture of emulsion paints, and until recently have tended to be based on dispersions of relatively large polymer particles (particle size 0.15-0.25 x 10 m). Dispersions are now becoming available which offer superior performance as floor sealers. The chemical and water resistance of the various polymer dispersions which have been used in the past vary considerably from the PVA types, which are rapidly softened and eventually washed out by water, to acrylic and SBR types which exhibit excellent resistance to a wide range of chemicals. Water-based sealers are gaining wider acceptance because of... 

Additional purification of the product and improvement of particle size and shape can be achieved by re-ciystallization. The process consists of sequential dissolutions of potassium heptafluorotantalate in appropriate solutions at increased temperatures, filtration of the solution to separate possible insoluble parts of the product and cooling of the filtrated solution at a certain rate. The precipitated crystals are filtrated, washed and dried to obtain the final product. Re-crystallization can be performed both after filtration of the preliminary precipitated salt or after drying if the quality of the product is not sufficient. HF solutions of low concentrations are usually used for re-ciystallization. In general, even water can be used as a solvent if the process is performed fast enough. Nevertheless, practical experience suggested the use of a 30—40% HF solution within the temperature interval of 80-25°C, and a cooling rate of about 8-10°C per hour. The above conditions enable to achieve an acceptable process yield and good performance of the product. 

A surprisingly low concentration of water can reduce the viscosity such that reclaimed PET cannot be used for the blow molding of bottles with acceptable physical properties. The established solution to the moisture problem is to dry the recycled PET in special dryers prior to use. However, the drying process is both time and energy intensive. Paper labels can cause problems in PET recycling if they decompose during washing and removal. The paper fibers formed can produce cellulose fibers that are difficult to remove from the reprocessed PET.1... 

AT-acetyltryptamines could be obtained via microwave-assisted transition-metal-catalyzed reactions on resin bound 3-[2-(acetylamino)ethyl]-2-iodo-lH-indole-5-carboxamide. While acceptable reaction conditions for the application of microwave irradiation have been identified for Stille heteroaryla-tion reactions, the related Suzuki protocol on the same substrate gave poor results, since at a constant power of 60 W, no full conversion (50-60%) of resin-bound 3-[2-(acetylamino)ethyl]-2-iodo-lH-indole-5-carboxamide could be obtained even when two consecutive cross-coupling reaction cycles (involving complete removal of reagents and by-products by washing off the resin) were used (Scheme 36). Also under conventional heating at 110 °C, and otherwise identical conditions, the Suzuki reactions proved to be difficult since two cross-coupling reaction cycles of 24 h had to be used to achieve full conversion. 

It may become necessary to work up solid products with the same solvent as used for crystallization. Cakes should not be allowed to dry out before washing, as air or inert gases result in evaporation of the solvent, and this may re.sult in the deposition of impurities, present in the dis.solved state, on the crystals. Such impurities when deposited are difficult to wash. In. some ca.ses washing of wet cake is done by replacing the solvent with another one, typically having a lower boiling point, so that in the final material loss of drying is within limits and the new solvent is more acceptable than the earlier one. 

Decaffeination of Coffee and Tea This application is driven by the environmental acceptability and nontoxicity of CO2 as well as by the ability to tailor the extraction with the adjustable solvent strength. It has been practiced industrially for more than two decades. Caffeine may be extracted from green coffee beans, and the aroma is developed later by roasting. Various methods have been proposed for recovery of the caffeine, including washing with water and adsorption. 

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