Vacuum filter systems

Vacuum filter systems consist of a horizontal cylinder partially submerged in a tank of biosolids. A layer of porous filter media fabric or tightly wound coils covers the outer surface of the cylinder. As the cylinder surface passes through the tank, a layer of biosolids adheres to the cylinder and vacuum is applied.61 The dewatered biosolids cake is then scraped off the fabric at up to 30% solids. 

An aliquot of the diatom sample is brought down onto a Nucleopore filter (2.0 pm pore size will work for most diatoms) using a hand pump or light vacuum filter system. 

Equipment. A three-neck distillation flask was used as a reactor. In a typical run, the flask was charged with waste oil and demetallizing reagents. The content was agitated and heated by a mechanical stirrer and heating mantle respectively. The reaction was carried out at atmospheric pressure, and water vapor and light ends were condensed and collected during the process. Oil was filtered immediately after the reaction by means of a vacuum filteration system, or allowed to settle down at constant temperature for a sedimentation study. 

Finely divided products, such as ground quicklime and hydrated lime, are loaded into air pressure discharge tankers for transport. A flexible chute is used, which fits the loading hatch of the vehicle, and incorporates an extraction hood connected to a vacuum filter system. The hood removes both displaced and conveying air emerging from the hatch. 

Figure 13. Process flow sheet for a typical Rotary Vacuum Filter System. 286...

Dewatering of high value products and particle systems sensitive to high pressure drops are the most likely candidates for electrofiltration. The Dorr-OHver Electrofilter is a commercial example of a vacuum filter adapted for electrofiltration. 

Most continuous pressure filters available (ca 1993) have their roots in vacuum filtration technology. A rotary dmm or rotary disk vacuum filter can be adapted to pressure by enclosing it in a pressure cover however, the disadvantages of this measure are evident. The enclosure is a pressure vessel which is heavy and expensive, the progress of filtration cannot be watched, and the removal of the cake from the vessel is difficult. Other complications of this method are caused by the necessity of arranging for two or more differential pressures between the inside and outside of the filter, which requires a troublesome system of pressure regulating valves. 

The KDF filter was first tested in prototype on a coal mine in northern Germany. It was installed in parallel with existing vacuum filters and it produced filter cakes consistendy lower in moisture content by 5 to 7% than the vacuum filters. Two production models have been installed and operated on a coal mine in Belgium. The filter is controlled by a specially developed computer system this consists of two computers, one monitoring the function of the filter and all of the detection devices installed, and the other controlling the filtration process. The system allows optimization of the performance, automatic start-up or shut-down, and can be integrated into the control system of the whole coal washing plant. 

The softened seawater is fed with dry or slaked lime (dolime) to a reactor. After precipitation in the reactor, a flocculating agent is added and the slurry is pumped to a thickener where the precipitate settles. The spent seawater overflows the thickener and is returned to the sea. A portion of the thickener underflow is recirculated to the reactor to seed crystal growth and improve settling and filtering characteristics of the precipitate. The remainder of the thickener underflow is pumped to a countercurrent washing system. In this system the slurry is washed with freshwater to remove the soluble salts. The washed slurry is vacuum-filtered to produce a filter cake that contains about 50% Mg(OH)2. Typical dimensions for equipment used in the seawater process may be found in the Hterature (75). 

In order to upgrade the melamine, the solution obtained after prethickening and stripping is treated with activated carbon passed over a clarifying filter and fed to a two-stage vacuum crystallization system from which the pure melamine is recovered in a continuous centrifiige. Stainless steel is used as constmction material for nearly all parts of the equipment exposed to product streams. 

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. 

Plate filters are suitable for filtration of batch fermentation broth accumulated biomass must be cleaned periodically. A rotary dram vacuum filter is used for a continuous system. 

The ice bath is removed after addition of the sodium cyanide, and the mixture is stirred for 4 hours. The organic layer is separated, and the aqueous layer is extracted with three 500-ml. portions of ether. The combined ethereal extracts and organic layer are washed with two 100-ml. portions of cold water and dried over anhydrous magnesium sulfate. The ethereal solution is filtered, and the ether is removed at atmospheric pressure. The residue is transferred to a vacuum distillation system and distilled under reduced pressure (Cauiionl See Note 2). The yield of dlmethylaminophenylacetonitrile boiling at 88-90°/l.9-2.1 tnm. is 842 844 g. (87-88%) (Notes 3 and 4). 

Generally, in MPPs one centrifuge or pressure/vacuum filter, one drier, and one fractionation system of reasonable capacity are installed for every two or three reactors/crystallizers. On average, about 2 to 5 m solvent storage capacity and the same amount for intermediates are needed per 1 m of reactor capacity. 

Roll discharge systems, with rotary drum vacuum filters, 11 356-357 Rolled lead alloys, mechanical properties of, 14 775t... 

A third plant uses a chemical precipitation step for removing arsenic and zinc from contaminated surface water runoff. Ferric sulfate and hme are alternately added while the wastewater is vacuum-filtered and sludge is contract-hauled. The entire treatment system consists of dual-media filtration, carbon adsorption, ion exchange, chemical precipitation, and vacuum hltration. Sampling results across the entire treatment system indicated that arsenic was reduced from 6.9 to 0.2 mg/L and zinc from 0.34 to 0.11 mg/L. 

Vacuum filtration system combining a filter unit with a receiver flask for processing and storing volumes from 150 to 1,000 mL. 

To investigate the storage stability of these dyes, a 28-day storage study was undertaken. Filters were spiked and dried by the procedure described in the experimental section. Sixty liters of humidified air (75% relative humidity) were drawn through each spiked filter before storage, using the previously described vacuum pump system. During the... 

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