ABSTRACT Recent advances in the field of light emitting diodes have enabled the production of new all solid- state fluorometers. High intensity light emitting diodes are used to excite the fluorophores and photocells are used to detect the emission. These fluorometers are small, with low power consumption, but they are highly sensitive with exceptional stability and low noise. The instruments are used in conjunction with water treatment chemicals that contain an inert fluorescent tracer. Handheld, battery- powered units are used for grab sample analysis and provide greatly improved accuracy with less testing time for systems where chemical addition is controlled manually. On-line fluorometers can provide continuous signals for a variety of automated control schemes. Important system diagnostics such as cycles of concentration and polymer recovery measurements are easily performed. The low cost and versatility of these units brings tracer technology to a broad range of facilities where it was previously not viable.
INTRODUCTION Manpower is a constantly dwindling resource in today's boiler house. Boiler operators are continually called upon to spend more time with other maintenance tasks. As the job market becomes tighter, personnel with less experience and training occupy positions as boiler operators. In response to this pressure, boiler treatment programs must become more forgiving and require less operator time for testing and adjustment.
The use of fluorescent tracers for system diagnostics and dosage control of treatment chemicals is a proven method for reducing operator work load and improving system performance. 1' 2 However, application of tracer technology was to some degree limited by the type of equipment that was necessary for accurate and reliable measurement of fluorescence in the field. Previous generations of fluorometers used gas discharge lamps as excitation light sources and photomultiplier tubes to detect the light emitted from the fluorophore. These devices have the advantages of long life and very high sensitivity. They are also quite versatile and can be adapted to fluorophores utilizing wavelengths throughout most of the ultraviolet and the entire visible spectrum. Careful design and painstaking construction techniques made these instruments extremely rugged and reliable in virtually any industrial environment.
Although the previous generation of fluorometers was highly valuable there is always room for improvement. Both the gas discharge lamp and the photomultiplier tube are high voltage devices requiring a large and heavy transformer. They also consume too much power to be operated with a battery of convenient size. In addition, these devices require several minutes of warm-up time to reach their ultimate level of stability. While photomultiplier tubes are extremely sensitive, they have a limited dynamic range of response. This means that the detection circuit must be balanced either optically or electronically to be sensitive at the fluorophore concentration range of interest. For boiler applications, the practical implication of this limitation in the detector was that the fluorometers sometimes needed to be recalibrated when switching from feedwater to blowdown samples. All these factors conspired to limit the convenience of fluorometers designed for grab sample analysis since they would be fairly large and heavy devices that required line power and a warm-up period.
All the components of the previous generation of fluorometers represent well-known and readily available technology, but the ones mentioned in the preceding paragraph are not used in consumer electronics applications. Specialty devices generally carry a higher price tag than th
As the dredging Industry strives to streamline its offshore operations to be more time and cost efficient, applications for the microprocessor systems used to monitor rig operations are increasingly finding their way into the cabs of heavy equipment. The use of small, sophisticated data acquisition systems, combined with operator friendly graphic displays, allow increased production with greater precision in excavation.
Using experience and technology gained from years of offshore transport monitoring, systems have been designed and installed to bring the application of real time operator feedback to the dredging industry. This paper explores the use of offshore Instrumentation and microprocessor systems in dredging applications. It details the use of graphic displays to increase operators/equipment accuracy and efficiency while excavating both above and below the waterline.
Outlined are two such field installations, along with operator comments after extended use. These Installations both applied existing motion monitoring technology to lower operator error, speed excavation, and provide increased accuracy of the finished slope or surveyed profile.
The use of small dedicated microprocessor systems providing real time operator feedback IS tally new in the dredging Industry. The value of using real-time motion feedback as an aide in the towing of offshore structures has been proven in the field. The results of the first Installations Using this technology in the dredging Industry have been promising, further refinements through application can only Increase the benefits gained.
During the past several years advances in large scale Integrated Circuits have made high resolution black and White, and color graphics available to the average personnel computer user. Apple computer started the trend towards graphic user Interfaces with the Macintosh. IBM followed with several levels of color graphics hardware and the Industry produced software to support It.
Graphic also for heavy equipment control, and user operation and display in surveying have been slow in coming. Previous reasons were due to cost and complexity of such systems. These types of displays and control Interfaces have been used as new found tools With Which to Increase ones productivity in the office. With the advent of low cost graphic hardware and greatly increased software support, the in-field use of these new tools has been realized.
Graphic displays allow operators to react to the information presented about their equipment in a natural, easy to interpret form. The relative Positions of objects and their interactions can be quickly recognized and understood from a picture. A Position monitoring system without graphics would force an operator to constantly interpret a changing numerical display. The numbers would then be used to form a mental picture of the Objects proximities to earn other. It the numbers were misunderstood or transposed then the precision of the excavation would lessen and the time to complete It would Increase. The same monitoring system with graphics allows the operator, at a glance, to discern the position of his equipment and the progress of his work as compared With the Intended profile to be grades.
Benefits to be gained Include reduced operator fatigue, unsupervised operation by operators for extended periods, and greater precision in excavation. The constant monitoring of the work as it progresses, allows fewer interruptions for checks of the slope by survey teams.