OU report - Title : FILTER PRESS Objective : 1.To test the...

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Title : FILTER PRESS Objective : 1.To test the performance of plate and frame filter press. 2. To learn the process and working principle of filter press 3. To master the technique using filter press Introduction : Filtration may be defined as a unit operation in which the insoluble solid component of a solid-liquid suspension is separated from the liquid component by passing the latter through a porous membrane, which retains the solid particles on its upstream surface or within its structure or both. The solid-liquid suspension is known as the feed slurry, the liquid component that passes through the membrane is called the filtrate and the membrane itself is referred to as the filter medium. The separated solids are known as the filter cake, once they form a detectable layer covering the upstream surface of the medium. Filtrate passing through a filter encounters three types of resistance, namely 1. that offered by the channels and ports of the filter itself 2. that offered by the filter medium. 3. that offered by the filter cake. The total pressure drop across the filter is equivalent to the sum of the pressure drop, resulting from these resistances. The total resistance is also proportional to the viscosity of the fluid. Filtration of a suspension can be carried out in one of the following conditions : 1. Constant pressure and decreasing (filtration) flow 2. Constant flow and increasing pressure Filter presses are sometimes called "Plate-and-Frame Filters." This refers to the style of filter element that was most prominent in the mid 1800's until the late 1960's. The primary usage of a filter press is as a "fixed volume, batch pressure filter." As a fixed volume filter, it is built to hold a specific quantity of solids. The term "batch"
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refers to the fact the cycle must be stopped to discharge the collected “filter cake” prior to restarting a cycle. "Pressure" is created by the feed pump in the separation process. The filter press may also be used as a "polishing" filter to remove minute quantities of solids from an influent stream. In these applications the press is not sized for the quantity of solids holding capacity but for maximum filtration area and hydraulic throughput. When used as a polishing filter, generally a dry filter cake is not developed. Rather, when throughput flow rates drop to an unacceptable level, the cycle is ended. The last most common usage of the filter press is as a "variable volume" filter through the use of a filter plate known as a diaphragm or membrane plate. This type of plate has a flexible drain-field which when sealed around the edges forms an integral bladder or diaphragm that may be inflated to physically press additional liquid from the filter cake. This process can significantly reduce the typical elapsed time for a press cycle and produce a dryer cake product, or more uniform cake dryness from cycle to cycle. A commonly used design is the Plate-and-frame press. In this type of filter
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This note was uploaded on 04/27/2010 for the course BSTM 3301 taught by Professor Ali during the Spring '10 term at Zhejiang University.

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OU report - Title : FILTER PRESS Objective : 1.To test the...

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