Pressure Leaf Filter Systems

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The Sharplex-NFM Pressure Leaf Filter is a batch filter using porous leaves positioned vertically in either a vertical or a horizontal ASME-code stamped pressure vessel. The filter offers large filtration area in relatively small space. The entire filtration process occurs within a totally closed vessel for safe control of toxic, volatile, chemically reactive, or temperature sensitive processes. Filter cake can be discharged either dry with pneumatic vibration or wet with oscillating sluicing.

Pressure Leaf Filters are used on processes with fine particles suspended at low concentrations. The filters can form cakes with different cake thicknesses. The vessel can be steam jacketed to control viscosity or temperature sensitive conditions. The filter leaves can be designed for different pressure drops and particle retention.

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Horizontal Leaf Pressure Filters are used with high density solids and can be operated intermittently because the cake will not fall off the septum. However, filtration only occurs on the top half of the filter leaf.

Typical applications include food and beverage, vegetable oil, carbon removal, molten sulfur, chemical polishing and clarification.

In the edible oil process, the following filtration steps are accomplished with Sharplex-NFM Pressure Leaf Filters:

Foots from crude oil in the oil mill
Bleaching earth from bleached oil
Catalyst from hydrogenated oil
Wax from winterized oil
Polishing after bleaching and deoderization
Miscella filtration in solvent extraction process

Semi-Continuous Pressure Filtration

The Rotofilt-NFM Automatic Vertical Pressure Filter is a semi-continuous filter applied on variable volume conditions with horizontal plates. It commonly operates with short cycle times -- usually less than 10 minutes -- to form, wash, and dry porous filter cakes with 16 bar pressure. This filter works best with medium to low cake resistance filter cakes such as clays and dyestuffs. Floor space is small; the critical dimension is height. Operator manpower is reduced because the filter operates continuously with full automation.

Automatic Vertical Pressure Filter uses the slurry feed pump to uniformly fast fill the horizontal chamber plates. Then, cake washing and dewatering are accomplished with rubber diaphragms inflating against the cake. The compressed cake eliminates the risk of cake cracking so both the wash solute and final air blow thoroughly diffuse the cake.

When discharging the filter cake, the endless filter fabric is driven from all the filter plates simultaneously. The filter cakes discharge from both sides at the same time. The filter fabric also is washed on both sides in an enclosed belt wash box.

The machine can be fabricated with a wide range of materials such as steel of AISI 304, 316, 316L, 316Ti. The filter plates can be fabricated from similar metals or with molded polypropylene.

Operating Principles