Liquid purification or separation – Flow – fluid pressure or material level – responsive – Prefilt deverting to drain by prefilt accumulation
Reexamination Certificate
2000-03-03
2001-06-05
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Flow, fluid pressure or material level, responsive
Prefilt deverting to drain by prefilt accumulation
C210S106000, C210S306000, C210S407000, C210S456000, C210S459000, C210S510100
Reexamination Certificate
active
06241878
ABSTRACT:
FIELD OF THE INVENTION
A porous piezoelectric in-line filter in a pipeline liquid stream. Its piezoelectric effect is supplemented by a periodic flow across the surface of the filter to remove particulates which are displaced from the surface of the filter and from the stream.
BACKGROUND OF THE INVENTION
Especially for viscous liquids such as fuel oil, it is prudent practice to remove non-combustible particulates before storing the liquid, and especially before feeding it to a combustion system. In-line filters have long been used for this purpose. The advantages of fine filtering of other liquids such as water and solvents are also well-known, and such applications are contemplated herein.
The potential disadvantages of in-line filters are well-known, and are largely centered on the ultimate reduction of efficiency caused by the plugging of the filter pores, and the difficulty of removing the separated particulates from a closed system. One common technique is to provide two filters in parallel circuitry with one another. While one side is open to filtered flow, the other side is closed and backwashed. It is, of course, also possible to shut down a system for backwash and purge of particulates at the cost of down time. The saving of downtime is reduced by the cost of duplicating filtration facilities.
It is an object of this invention to provide a porous ceramic filter which by its own vibrations can release from its surface the particulates that are detained by it, to provide a swirling motion in the stream to sweep the filter surface, and to provide a periodically actuated purge circuit to remove particulates from the stream just upstream from the filter surface.
BRIEF DESCRIPTION OF THE INVENTION
A self-cleaning porous filter for a liquid stream confined in a pipe. The filter extends across the flow area. It is a ceramic of the type which upon appropriate excitation acts as an ultrasonic transducer. A power supply applies power to cause the vibration and dislodge particulates from the surface of the filter. A rib in the inside wall of the pipe provides a laminar swirl to the outer boundary of the liquid stream so part of it sweeps across the filter face.
A sump valve opens into the pipe immediately upstream from the filter face. It is periodically opened while the filter is actuated to remove a local quantity of particulate-laden liquid and discharge it into a sump.
The pores of the filter are selected to retain particulates of a specified size, and the power supply and sump valve are actuated when the pressure drop caused by plugging of the pores exceeds a premissible value, which indicates that it is time to clean the pores.
The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:
REFERENCES:
patent: 2087385 (1937-07-01), Naujoks
patent: 3305481 (1967-02-01), Peterson
patent: 3463321 (1969-08-01), Van Ingen
patent: 4279751 (1981-07-01), Fishgal
patent: 4904394 (1990-02-01), Clarke et al.
patent: 5053141 (1991-10-01), Laiho
patent: 5997744 (1999-12-01), Limaye
Cecil Terry K.
Drodge Joseph W.
Mon Donald D.
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