Liquid purification or separation – Processes – Including controlling process in response to a sensed condition
Reexamination Certificate
2000-05-31
2001-06-19
Barry, Chester T. (Department: 1724)
Liquid purification or separation
Processes
Including controlling process in response to a sensed condition
C210S411000
Reexamination Certificate
active
06248243
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
This invention relates to the continuous monitoring of the effluent of a filter. The meter measures the quality of the filter discharge and controls the filter cycle. This, in turn, maximizes the quality of the filter effluent.
2. Background of the Invention
Filters are used to remove solids of varying composition, concentration and size distribution from flowing fluids. Therefore, various types of filters are used to remove these solids. Differential pressure across a filter increases as the filter collects contaminants from the fluid runs. Most filters have cycles where they filter, backwash to remove the collected contaminants and filter again. It is an indication of length of the filtration stage because harmful by-pass of solids occurs at high differential pressure. Solids by-pass results in poorer water quality, which is one of the problems of inefficient filter operation.
One approach has been to measure the solids concentration of the filter effluent regardless of the size distribution or the composition of the solids. Solids concentration alone is not solely indicative of water quality related to injectivity into a producing formation in a waterflood. Common contaminants, such as oil and scale, can cause poor water quality, yet they remain undetected by solids meters. This often indicates that filtration alone is adequate for achieving water quality which will protect water injection wells from damage. Inadvertent damage by oil droplets and scale would have been overlooked.
THE PRIOR ART
The prior art is represented by U.S. patents. U.S. Pat. No. 3,357,236 to Kasten utilizes two filter units in series to remove only the solid contaminants, and then only the water contaminants, and then measures the pressure differential across the separate filters. U.S. Pat. No. 3,499,315 to Marino has a filter element selected for maximum acceptable limit of the system placed between a fluid reservoir and a suction pump. U.S. Pat. No. 3,452,586 to Childs et al pumps fluid through a filter and measures the pressure differential across the filter. Periodically the filter is back washed with primary filtered fluid. U.S. Pat. No. 3,934,471 to White et al measures the concentration of the material and the flow rate and uses these measurements to give an output proportional to the product of the signals, this being proportional to the rate of passage of the material. U.S. Pat. No. 4,786,473 to Mukogawa divides a water sample and passes the divided samples through filters of different sizes while measuring the respective flow rates. The ratio of the flow rates is related to the concentration of the solids.
Patents related to the aspects of the microprocessor and its prior art are also presented. U.S. Pat. No. 5,319,964 to Stephenson et al. utilizes a single pressure transducer connected to a computer having a memory in which fluid level-to-fluid volume conversion data are stored. U.S. Pat. No. 5,146,764 to Bauman et al. utilizes operational parameters to control a variable width diffused section of a centrifugal compressor. The control system measures flow and temperature to accomplish this. U.S. Pat. No. 5,505,763 to Reighard et al. gives a control system for constant air flow through a powder collector. The static pressure and fan speed are adjusted by the control system of the cartridge filters. U.S. Pat. No. 5,621,657 to Ferri measures pressure across an orifice. The pressure transducer unit is connected via communication line to an analog to digital input channel connected to computer system. Computer logic to determine the type of pressure measurement is presented.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, the quality of a water or fluid is monitored by a cartridge filter element. The sensitivity of the monitoring element to changes in water quality is measured by the fluctuations in rate and differential pressure across it. Further, the application of the meter in monitoring water quality for injection into the subsurface is ideal since the cartridge filter element models a formation better than a single or a bundle of capillaries. Flow channels of a filter intersect much as those of a porous rock. Along with the similar matrix, the flow direction is simulated; radial flow has a velocity gradient in the direction of flow. Velocity is inversely proportional to the position along the radius of flow away from the wellbore. While the monitor filter element simulates the wellbore, sensors signal a microprocessor, which calculates the transmissibility of the filter element as water quality changes. Filtration ratio is the ratio of transmissibility, at any time, divided by the initial transmissibility of the monitor cartridge filter. The changes in primary filter effectiveness are observed by the microprocessor. Computer logic dictates alarm and control signals, which ensure optimum water quality.
It is the principal objective of this invention to provide a filter element of a specific degree of filtration for determining the quality of effluent from a primary filter. The length of the filter cycle of the primary filter is established by the monitor filter, the life of which is dependent on the effluent water quality. The meter is configured so the monitor element can be backflowed, flushed or replaced.
It is another object of the invention to determine the need for back flowing the monitor filter element and signal the appropriate valves to facilitate the backflow step. It is yet another object of the invention to signal the need to manually flush the monitor filter with a reactive fluid to remove the contaminant and restore transmissibility to the monitor element.
The foregoing and other objects and advantages of the invention will appear in the following detailed description.
REFERENCES:
patent: 4086166 (1978-04-01), Martin
patent: 4753724 (1988-06-01), Womble
patent: 4882061 (1989-11-01), Petrucci
patent: 5082557 (1992-01-01), Grayson
patent: 5525225 (1996-06-01), Janik
Barry Chester T.
Egan Russell J.
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