Filtration, cost vacuum

Membrane operations have been extensively used in the food industry because they require less manpower, are more efficient, and have a shorter processing time than traditional separation techniqnes, so operational costs are considerably lower than traditional processes [105], For instance, membrane separation processes to clarify and concentrate liquids are less costly than conventional filtration and vacuum evaporation, justifying their application in this field [106]. The primary applications of membranes in the food industry are in the beverage (wine, beer, fruit juices, etc.) and dairy (whey protein concentration, milk protein standardization, etc.), processing industries in the processing of egg prodncts, to a lesser extent, and in water purification. 

Insulating oil plays a vital part in many types of electrical equipment, not only as an insulant but also as a coolant in transformers and as an arc extinguishing medium in circuit breakers. In each case, efficient operation of the equipment depends upon the purity of the insulating oil, which in service can be contaminated by oxidation, condensation and the presence of solids, such as colloidal carbon, formed by arcing in circuit breakers. The electrical and physical properties of the oil may be seriously affected, resulting in reduced operating efficiency or even equipment failure. Frequent replacement of the oil wiU be too costly, and reconditioning by filtration and vacuum dehydration to remove all contaminants is the economic answer. 

The so-called hyperbar vacuum filtration is a combination of vacuum and pressure filtration in a pull—push arrangement, whereby a vacuum pump of a fan generates vacuum downstream of the filter medium, while a compressor maintains higher-than-atmospheric pressure upstream. If, for example, the vacuum produced is 80 kPa, ie, absolute pressure of 20 kPa, and the absolute pressure before the filter is 150 kPa, the total pressure drop of 130 kPa is created across the filter medium. This is a new idea in principle but in practice requires three primary movers a Hquid pump to pump in the suspension, a vacuum pump to produce the vacuum, and a compressor to supply the compressed air. The cost of having to provide, install, and maintain one additional primary mover has deterred the development of hyperbar vacuum filtration only Andrit2 in Austria offers a system commercially. 

The disk filter is similar to the dmm in operation, but filtration is conducted using a series of large diameter filter disks that carry the filter medium on both sides of the disk. They are connected to the main horizontal shaft and partly immersed in the feed slurry. The central shaft is connected by a set of valves which serve to provide vacuum and air as in dmm filters. As the disk sections submerge during rotation, vacuum is appHed to form a cake on both sides of the disk. The cycle of operation is similar to that in a dmm filter. One unit can have as many as 12 disks of up to 5-m diameter. Disk filters, both compact and cost effective, are used extensively in the iron ore industry to dewater magnetite concentrates. 

Pressure leaf filters are used to separate much the same lands of slurries as are filter presses and are used much more extensively than filter presses for filter-aid filtrations. They should be seriously considered whenever uniformity of production permits long-time operation under essentially constant filtration conditions, when thorough washing with a minimum of hquor is desired, or when vapors or fumes make closed construction desirable. Under such conditions, if the filter medium does not require frequent changing, they may show a considerable advantage in cycle and labor economy over a filter press, which has a lower initial cost, and advantages of economy and flexibility over continuous vacuum filters, which have a higher first cost. 

The cost of the filter station includes not only the installed cost of the filter itself but also that of all the accessories dedicated to the filtration operation. Examples are feed pumps and storage facihties, precoat tanks, vacuum systems (often a major cost factor for a vacuum filter station), and compressed-air systems. The dehvered cost of the accessories plus the cost of installation of filter and accessories generally is of the same order of magnitude as the dehvered filter cost and commonly is several times as large. Installation costs, of course, must be estimated with reference to local labor costs and site-specific considerations. 

Charcoal is generally satisfactorily activated by heating gently to red heat in a crucible or quartz beaker in a muffle furnace, finally allowing to cool under an inert atmosphere in a desiccator. Good commercial activated charcoal is made from wood, e.g. Norit (from Birch wood), Darco and Nuchar. If the cost is important then the cheaper animal charcoal (bone charcoal) can be used. However, this charcoal contains calcium phosphate and other calcium salts and cannot be used with acidic materials. In this case the charcoal is boiled with dilute hydrochloric acid (1 1 by volume) for 2-3h, diluted with distilled water and filtered through a fine grade paper on a Buchner flask, washed with distilled water until the filtrate is almost neutral, and dried first in air then in a vacuum, and activated as above. To improve the porosity, charcoal columns are usually prepared in admixture with diatomaceous earth. 

The disadvantages associated with centrifugation are (I) without the use of chemicals the solids capture is often very poor, and chemical costs can be substantial (2) trash must often be removed from the centrifuge feed by screening (3) cake solids are often lower than those resulting from vacuum filtration and (4) maintenance costs are high. 

This cycle of vaporisation of the solvent, condensation, extraction, and vacuum-filtration may be repeated any number of times in a solid-fluid serial extractor. The occurrence of an extractive material fluid bed as a result of the flow of boiling hot vapour provides for effective extraction, while pressure filtration provides for short cycle times. This functional principle makes it possible to achieve filtration pressures which are 50-100 times more effective than when using the Soxhlet method, where only the low hydrostatic pressure of the extractive fluid operates. Solid-fluid-vortex extraction according to the proprietary FEXTRA (Feststoff Extraktion) principle is low cost. 

Whether filtering material through a cotton-filter or a coffee filter it helps if the thinner parts of the solution are filtered first, followed by the mushy and more bulky components (which may clog the pores of your filters as you strain.) The better your filtration, the more rapid and efficient your emulsions, also resulting in a cleaner product. Cotton must be specifically used. Other fibers have the potential to react with our solvents. A tea strainer (wire strain) can be a simple way to separate bulk ruffage. Another way to improve this method is to use a vacuum filter. There are several varieties, the most affordable being a water vacuum filter that attaches to a household faucet. These cost about 30.00 and are very quick, useful and effective. 

The spent liquors may contain lint and residual size that can be removed by filtration. Weakly alkaline liquors represent a cost problem, however. Although limited amounts of less dilute liquor may be recycled and used in boiling-off or scouring, the major proportion becomes a rather troublesome component of the effluent load. Neutralisation simply increases the salt content of the effluent. Recovery of the alkali by vacuum evaporation is the usual procedure [282,283]. 

Solvent-Refined Coal Process. In the 1920s the anthracene oil fraction recovered from pyrolysis, or coking, of coal was utilized to extract 35—40% of bituminous coals at low pressures for the purpose of manufacturing low cost newspaper inks (113). Tetralin was found to have higher solvent power for coals, and the I. G. Farben Pott-Broche process (114) was developed, wherein a mixture of cresol and tetralin was used to dissolve ca 75% of brown coals at 13.8 MPa (2000 psi) and 427°C. The extract was filtered, and the filtrate vacuum distilled. The overhead was distilled a second time at atmospheric pressure to separate solvent, which was recycled to extraction, and a heavier liquid, which was sent to hydrogenation. The bottoms product from vacuum distillation, or solvent-extracted coal, was carbonized to produce electrode carbon. Filter cake from the filters was coked in rotary kilns for tar and oil recovery. A variety of liquid products were obtained from the solvent extraction-hydrogenation system (113). A similar process was employed in Japan during Wodd War II to produce electrode coke, asphalt (qv), and carbonized fuel briquettes (115). 

Concentration. Clarified filtrates, centrates, or column eluates are usually too dilute for use in their specific applications, thus, substantial amounts of water must be removed. This can be achieved by evaporation or by ultrafiltration. Concentration methods used in industrial settings, such as evaporation, which is done under vacuum, and solvent extraction, may or may not be suitable for dewatering proteins because of their potential for thermal or chemical denaturation, and due to high energy costs associated with evaporation. The benefit of evaporation is that nonvolatile compounds that may stabilize the proteins are retained. 

A simple rotary-filter system consists of a rotary filter and auxiliary equipment such as a cort ressor, a filtrate receiver, a filtrate pump, a vacuum punp, and a separator-silencer, as shown in Figure 6.10. Auxiliary equipment usually runs 25 to 40% of the filter cost [25]. When solids deposit on the drum, air and filtrate are drawn into the filtrate receiver, which is a gas-liquid separator. After... 

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