Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1999-09-07
2001-06-19
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S04050R, C340S605000, C417S063000, C417S395000
Reexamination Certificate
active
06247352
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a diaphragm pump for pumping slurry, and more particularly to a monitoring system for determining when the diaphragm of the pump has begun to fail.
Slurry pumps are often used with gasifiers to pump slurries of coal, coke and/or carbon into the gasifier for conversion to carbon monoxide and hydrogen. A well known slurry pump includes a flexible diaphragm that is usually formed of rubber or some other, durable, flexible material. The diaphragm is deflected or pulsed by oil that is pressurized and depressurized in accordance with movement of a piston or plunger in the pump. Generally, a glycol-based oil is used as a working fluid for actuation of the diaphragm. The diaphragm shields the oil and the pump mechanism from a pump chamber or transfer chamber wherein slurry passes into and out of the pump.
Thus, when a slurry pump operates properly, the slurry is drawn into the pump chamber and pumped out of the pump chamber without encountering the actuating mechanism or working fluid of the pump. The pump diaphragm, due to the abrasive nature of the slurry as it moves in and out of the pump chamber, is subject to wear. Ultimately, the wearing action of the slurry on the diaphragm will cause the diaphragm to rupture, resulting in pump failure because of commingling of the slurry with the pump mechanism and the working fluid of the pump. Although gradual deterioration of the pump diaphragm is expected due to the wear imposed by the slurry movement, sudden rupture of the diaphragm can occur at unpredictable times.
A typical slurry pump often includes a visual port that is usually monitored periodically by an attendant to detect visible contamination of the oil in the pump which can indicate impending rupture of the pump diaphragm. However, visual monitoring is not a reliable means of detecting impending rupture of the pump diaphragm because slight leaks in a diaphragm at the earliest stages of diaphragm failure are generally not visually perceptible.
Once a slurry pump is rendered inoperable due to diaphragm rupture, the gasifier operation must be shut down while the slurry pump is either repaired or replaced. Any shutdown of a gasifier operation is burdensome and expensive since gasifier shutdown and start-up operations, as well as pump repair and replacement operations, are time consuming and expensive, and require immediate availability of skilled personnel.
Although rough forecasts can be made, based on statistical data, of when a diaphragm will rupture, there are no presently known means for precisely predicting the earliest stages of diaphragm breakdown before severe damage occurs to the pump mechanism. Consequently, skilled personnel are often required to monitor and maintain pump operations.
It is therefore desirable to provide a reliable method and means for detecting the earliest stages of diaphragm failure in a slurry pump so that the pump can be shut down for repairs before the diaphragm failure causes severe damage to the pump mechanism.
OBJECTS AND SUMMARY OF THE INVENTION
One of several objects of the invention is the provision of a novel method and means of accurately detecting any deterioration in a diaphragm of a diaphragm pump that results in a slight leakage of the diaphragm. Another object of the invention is the provision of a novel method and means for detecting an impending rupture of a diaphragm in a diaphragm pump before the rupture causes damage to the pumping mechanism. Another object of the invention is the provision of a novel method and means of detecting impending rupture of a diaphragm in a diaphragm pump without the need for personnel to monitor the diaphragm pump. Another object of the invention is the provision of a novel method and means which employs optic signals for detecting deterioration or impending rupture of a diaphragm in a diaphragm pump.
In accordance with the present invention, a diaphragm failure monitoring system is provided for automatically detecting leakage in a diaphragm of a diaphragm pump. The diaphragm pump includes a pumping chamber with a slurry inlet port and a slurry outlet port. The diaphragm pump also includes an operating chamber containing a working fluid. The diaphragm separates the pumping chamber from the operating chamber and isolates the slurry from the working fluid. A reciprocating piston pulsates the working fluid against the diaphragm to deflect the diaphragm and thereby pump the slurry into and out of the pumping chamber.
The monitoring system cooperates with the operating chamber which contains the working fluid of the diaphragm pump. The monitoring system includes a first optic fiber located at the operating chamber for transmitting an optic signal across the working fluid to an oppositely disposed, second optic fiber. The monitoring system generates a first electrical signal when the optic signal passes through uncontaminated working fluid, and an electrical signal different from the first electrical signal when the optic signal passes through contaminated working fluid. Thus, contamination of the working fluid as a first sign of diaphragm failure can be detected when a signal other than the first electrical signal is detected by the monitoring system.
In one embodiment of the invention, the monitoring system includes a hollow, optical cell secured to the pump at the operating chamber to receive a portion of the working fluid. The first and second optic fibers are connected to the optical cell to transmit and receive optical signals across the working fluid in the optical cell.
The invention also provides a method of detecting leakage in a diaphragm of a diaphragm pump in which the pump has an operating chamber for receiving a working fluid. The method includes transmitting an optic signal across the working fluid to a signal receiver for conversion to an electrical signal. The method further includes establishing a first electrical signal to function as a base measure when the received optic signal passes through uncontaminated working fluid, and establishing a second electrical signal different from the first electrical signal when the received optic signal passes through contaminated working fluid. In accordance with the foregoing method when the second electrical signal is established contamination of the working fluid due to diaphragm failure can be detected.
The invention therefore solves the problem of detecting slight deterioration leakage and impending rupture of a pump diaphragm. The invention achieves the foregoing objects by using an optical monitoring system which relies upon changes in the absorption of light by the working fluid in the pump due to fluid contamination to indicate deterioration or impending failure of the diaphragm before the diaphragm failure causes severe damage to the pump mechanism.
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Green Steven R.
Powell, Jr. David L.
Garber C D
Reinisch Morris N.
Rodman & Rodman
Texaco Inc.
Williams Hezron
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