Gas backwash of pleated filters
First Claim
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1. The method of gas backwashing pleated filters in a filter housing, said pleated filter having pores, said pores having a bubble point, said pleated filter defining an upstream volume and a downstream volume within said housing, comprising the steps of:
- A. discontinuing filtration;
B. withdrawing filtrate from said down-stream volume within said housing, establishing a gas pressure of at least about twice said bubble point of said filter in said downstream volume within said housing, and venting said upstream volume to ambient pressure;
C. flowing gas from said downstream volume within said housing, through said pleated filter, and into an upstream volume within said housing, at an applied pressure sufficient to blow solids out of said pores of said filter medium;
D. withdrawing solids within said up-stream volume of said housing by entrainment of material removed from said pleated filter in a wash liquid; and
E. repeating steps B, C, and D in a cycle until said pleated filter is cleaned to the required extent.
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Abstract
In critical filtration applications, filter cartridges are employed to replace ion exchange resin precoat filters to minimize the waste produced. The filter cartridges are backwashed with all gas and the liquid in the filter housing provides an active scouring effect as a result of the high levels of turbulence produced. The liquid, with entrained debris from the filter is minimized in volume.
96 Citations
11 Claims
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1. The method of gas backwashing pleated filters in a filter housing, said pleated filter having pores, said pores having a bubble point, said pleated filter defining an upstream volume and a downstream volume within said housing, comprising the steps of:
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A. discontinuing filtration; B. withdrawing filtrate from said down-stream volume within said housing, establishing a gas pressure of at least about twice said bubble point of said filter in said downstream volume within said housing, and venting said upstream volume to ambient pressure; C. flowing gas from said downstream volume within said housing, through said pleated filter, and into an upstream volume within said housing, at an applied pressure sufficient to blow solids out of said pores of said filter medium; D. withdrawing solids within said up-stream volume of said housing by entrainment of material removed from said pleated filter in a wash liquid; and E. repeating steps B, C, and D in a cycle until said pleated filter is cleaned to the required extent. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification