PEF-Filtration 制药工程与设备基础　Pharmaceutical Equipment Fundamentals　教学课件　.pptVIP

Pharmaceutical Equipment Fundamentals Filtration Filtration There are many different methods of filtration; all aim to attain the separation of substances. Separation is achieved by some form of interaction between the substance or objects to be removed and the filter. The substance that is to pass through the filter must be a fluid, i.e. a liquid or gas. Methods of filtration vary depending on the location of the targeted material, i.e. whether it is dissolved in the fluid phase or suspended as a solid. Liquid Filtration In the laboratory, filtration is often carried out using a form of Buchner funnel, and the liquid is sucked through the thin layer of particles using a source of vacuum. In even simpler cases the suspension is poured into a conical funnel fitted with a filter paper. In the industrial equivalent, difficulties are encountered in the mechanical handling of much larger quantities of suspension and solids. Principle of Liquid Filtration Diagram of simple filtration Large eg. water purification ore handling (mining industry) Small eg. Fine chemical industry Filtration Process During the initial period of flow, particles are deposited in the surface layers of the cloth to form the true filtering medium. The cake gradually builds up on the medium. The resistance to flow progressively increases. Two Basic Types of Filtration Cake filtration Depth filtration Filter Medium Filter Media Filter Media Woven materials Filter Media Filter Aids Flow through the Filter by gravity: the simplest method by pressure: compressed air on the feed side (or vacuum on the filtrate side), in the laboratory by force: exerted by a pump, in industry, reduce filtration time, no need to be mounted vertically Filtration Rate Examples The coffee filter to keep the coffee separate from the grounds HEPA filters in air conditioning to remove particles from air Belt filters to extract precious metals in mining. Furnaces use filtration t