Data processing: measuring – calibrating – or testing – Measurement system – Performance or efficiency evaluation
Reexamination Certificate
2002-06-24
2004-09-28
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Performance or efficiency evaluation
C700S274000
Reexamination Certificate
active
06799146
ABSTRACT:
This invention relates to a fossil-fired thermal system such as a power plant or steam generator, and, more particularly, to a method for continuously monitoring the thermal system at a location remote from the system, advising the system operator of corrections, improvements and warnings which improve system operations. Such advise may include diagnostic information, Dynamic Heat Rate and notice of tube failures.
BACKGROUND OF THE INVENTION
Although especially applicable to “Input/Loss methods” installed at coal-fired power plants, this invention is applicable to any other heat rate method installed at a thermal system for on-line monitoring; said method monitoring in a continuous manner (i.e., on-line) resulting in the determination of one or more of the following quantities: fuel flow, effluent flow, emission rates, fuel chemistry, fuel heating value, boiler efficiency, and/or system heat rate. Note that “The Input/Loss Method” and its associated technologies are described in the following U.S. patent applications Ser. No. 09/273,711 (hereinafter termed '711), Ser. No. 09/630,853 (hereinafter termed '853), Ser. No. 09/827,956 (hereinafter termed '956), Ser. No. 09/759,061 (hereinafter termed '061), Ser. No. 10/087,879 (hereinafter termed '879), and Ser. No. 10/131,932 (hereinafter termed '932); and in their related provisional patent applications and Continuation-In-Parts. One of several rudimentary Input/Loss methods is described in U.S. Pat. No. 5,367,470 issued Nov. 22, 1994 (hereinafter termed '470), and in U.S. Pat. No. 5,790,420 issued Aug. 4, 1998 (hereinafter termed '420).
The importance of accurately determining system heat rate is critical to any thermal system (heat rate being inversely related to system thermal efficiency, common units of measure being Btu/hour per kilowatt, or Btu/kWh). If practical hour-by-hour reductions in heat rate are to be made, and/or problems in thermally degraded equipment are to be found and corrected, then accuracy in determining system heat rate is a necessity as well as the quality of diagnostic information made available associated with degraded equipment. Any on-line monitoring method determining system heat rate must be properly maintained by the system's engineering staff. However, de-regulation of the electric power industry and/or economic down-turns may result in reductions of such engineering staffs. Further, the expertise needed to solve all problems arising at a thermal system may not be immediately available to the local staff. Further, given complexities of most thermal systems, and especially large commercial power plants burning coal, the system operator must keep track of dozens of important parameters which might impact system heat rate. The system operator has had no single parameter which feedbacks in real-time the consequences of his/her latest adjustments made to the system.
The problem of coping with complex thermal systems, and especially large commercial power plants burning coal, has never been adequately been address by the industry. A system operator would desire to have feedback on individual equipment, given adjustments to that equipment, as to how it impacts system heat rate. For example: if hot reheat temperature is lowered by the operator, what is the impact on system heat rate? Solution to such problems includes developing differential heat rates (hr
j
) for individual equipment and processes (e.g,, hr
Reheat
for the Reheater heat exchanger, hr
Comb
for the combustion process, etc.). One attempt to provide such operator feedback, as established art, is the use of the “controllable parameters” method to determine differential heat rates. In this method, a few (typically less than a dozen) measured system parameters are monitored relative to a reference value (also termed a bogey value or targeted value). For a turbine cycle associated with a conventional power plant, controllable parameters include at least throttle pressure, throttle temperature, reheat temperature and condenser pressure. For the boiler, controllable parameters may include stack tempers, excess air and/or Air/Fuel ratio. One teaching, known to the inventor, of controlling the Air/Fuel ratio to gain improvement in boiler performance is U.S. Pat. No. 4,969,408 by DH Archer and M Ahmed, issued Nov. 13, 1990.
In general, to assure quality feedback to the operator, differential heat rates should sum to system heat rate: &Sgr;hr
j
=HR; thus assuring that individual effects consistently impact the system as a whole. The problem is that current industrial practice, including the controllable parameters approach, computes differential heat rates in isolation. For example, the effects of changing hot reheat temperature is typically established by computer simulation of a turbine cycle, holding boiler efficiency constant, said effects then being assigned to the entire system. In like manner, boiler parameters are altered in computer simulators without consideration to effects on the turbine cycle. Even if such practices were applied to a system which maintains constant power output, burning uniform fuel environmental conditions alter with the seasons effecting such sensitivities. Coal-fired systems commonly operate with variable load and highly variable fuel quality. Indeed, use of such differential heat rates, computed in isolation, is the only known modality for on-line monitoring of thermal systems, with the exception of The Input/Loss Method. When the impacts of controllable parameters are computed in isolation, turbine cycle differential heat rates or boiler &Dgr;efficiencies have little value, offering no consistent feedback to the operator.
Whereas The Input/Loss Method, when employing the Fuel Consumption Index (FCI) technique, addresses a portion of the problem of determining differential heat rates; the FCI technique does not compute hr
j
values in isolation. The FCI technique, as establish art, computes differential heat rates based on principles founded in the Second Law of thermodynamics. The FCI technique forces system integration; hr
j
effects will always sum to system heat rate. However, a limiting requirement of the FCI technique is that it requires knowledge of the constituents of the As-Fired fuel, As-Fired fuel heating value, system mass balances (i.e., fuel, combustion gases and working fluid), and routine system “Operating Parameters”.
References for the Fuel Consumption Index technique include the following: F. D. Lang, and K. F. Horn, “Fuel Consumption Index for Proper Monitoring of Power Plants”,
Proceedings of the
1991
Heat Rate Improvement Conference
, Scottsdale, Ariz., sponsored by the Electric Power Research Institute, Palo Alto, Calif., May 7-9, 1991; also published as “Practical Experience with Second Law Power Plant Monitoring” in
Energy for the Transition Age
(Proceedings of the Florence World Energy Research Symposium, FLOWERS '92, Jun. 7-12, 1992, Florence, Italy), Edited by Sergio S. Stecco, Nova Science Publishers, Inc., Commack, N.Y., 1992, pages 487-501, ISBN 1-56072-083-4; also published as “Practical Experience with Second Law Power Plant Monitoring” in
Advances in Power Engineering
(Proceedings of International Power Engineering Conference, May 17-21, 1992, Hangzhou, People's Republic of China), Edited by Cen Kefa and David Y. S. Lou, International Academic Publishers, Beijing, China, 1992, pages 68-77, ISBN 7-80003-190-X/TK-17; also “Fuel Consumption Index for Proper Monitoring of Power Plants” is publically available, with updates through Revision 10 of Oct. 6, 1998, from Exergetic Systems, Inc., San Rafael, Calif. (note that this Revision 10 reflects all prior related technologies published elsewhere).
There is no known art related to this invention. There is, however, a clear need to improve the quality and consistency of information provided to operators of thermal systems, especially to those of coal-fired power plants, and to assist them in improving system heat rate.
SUMMARY OF THE INVENTION
This invention relates t
Barbee Manuel
Exergetic Systems LLC
Hoff Marc S.
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