Data processing: measuring – calibrating – or testing – Measurement system – Performance or efficiency evaluation
Reexamination Certificate
2001-10-03
2004-10-26
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Performance or efficiency evaluation
C702S031000, C702S089000, C700S274000, C700S287000
Reexamination Certificate
active
06810358
ABSTRACT:
This invention relates to a fossil-fired thermal system such as a power plant or steam generator, and, more particularly, to a method to synchronize data obtained from such systems. Particularly this invention relates to how synchronized data is corrected, given that these corrections are needed by established methods which describe, in real time, fuel chemistry, heating value, boiler efficiency, fuel energy flow, L Factors, F
C
Factors, and/or system heat rate.
BACKGROUND OF THE INVENTION
The importance of determining a fossil-fired thermal system's heat rate is critical if practical hour-by-hour improvements in heat rate are to be made, and/or problems in thermally degraded equipment within the system are to be found and corrected (note that heat rate is inversely related to system efficiency as: Heat Rate (Btu/kWh)=3412.1416/Efficiency). Analytical tools are available which allow in real time the determination of related thermal performance parameters. These are described in one or more of the following U.S. Pat. No. 6,522,994 (hereinafter termed '711 after its application Ser. No. 09/273,711), U.S. Pat. No. 6,584,429 (hereinafter termed '853 after its application Ser. No. 09/630,853), and U.S. Pat. No. 6,560,563 (hereinafter termed '956 after its application Ser. No. 09/827,956). '711 describes calculating in an explicit manner a fuel chemistry and fuel heating value of a fossil-fired thermal system using the Input/Loss Method; said fuel chemistry includes elementary fuel constituents, fuel water and fuel ash concentrations whose explicit computations are principally based on combustion effluents. '853 describes determining a boiler efficiency of a fossil-fired thermal system using the Input/Loss Method as comprising an Enthalpy of Products term, an Enthalpy of Reactants term, and a Firing Correction term all referenced to the fuel's calorific temperature. '956 describes determining a heat rate of the fossil-fired system using the L Factor method as comprising a corrected L Factor, a corrected total effluents mass flow rate and a produced electrical power. However, the process of determining chemistry and heating value of a fossil fuel, such as coal, in real time is strongly dependent on measurements of effluent CO
2
and O
2
, in addition to other “operating parameters” defined herein, and also discussed in '711. Data signals from instrumentation measuring these quantities may often be delayed in time relative to other data due to one or more of the following circumstances: physical measurement techniques; delays in non-uniform storage of data; and/or having an incorrect time stamp associated with the beginning or end of data averaging (versus, for example, a mid-point time or instantaneous time associated with other data).
This invention teaches through data synchronization techniques to correct time delays in data when such data is used to determine fossil fuel chemistry, heating value, boiler efficiency, fuel energy flow and/or system heat rate. Before the advance of technology allowing for such determinations, data synchronization as taught by this invention was not needed. However, established analytical tools employing these technologies, as learned during the course of developing this invention, require correction to achieve acceptable accuracies. Such established analytical tools used to determine fuel chemistry, heating value, boiler efficiency, fuel energy flow, system heat rate, L Factors, F
C
Factors, and related parameters, are discussed at length in '711, '853 and '956.
Analytical tools commercially available which claim to determine fuel chemistry, fuel heating value, fuel energy flow and/or system heat rate in real time include at least the following: the Input/Loss Method offered by Exergetic Systems, Inc. of San Rafael, Calif.; the OPTIMAX system offered by ABB Power Automation Ltd., Baden, Switzerland; the PMAX system offered by ScienTech, Inc., Idaho Falls, Id.; the L Factor Method offered by Exergetic Systems, Inc. of San Rafael, Calif.; the F Factor Method promoted by the Energy Research Center, Lehigh University, Bethlehem, Penn.; methods promoted by the Center for Electric Power, Tennessee Technological University, Cookeville, Tenn.; and any other method determining fuel chemistry, fuel heating value, fuel energy flow or heat rate in real time for thermal systems burning fossil fuels, and especially for system burning coal fuels. A rudimentary Input/Loss Method 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).
There is no known art to the present invention. None of the aforementioned commercial offerings, nor '470 and '420, nor '711, '853 and '956 and their related provisional patent applications and Continuation-In-Parts, teach any corrective techniques leading to data synchronization as is important when determining fossil fuel chemistry on-line. None of the aforementioned promote nor advance the idea that data synchronization is even required at the conceptual level. For situations involving power plant or steam generator monitoring using the Input/Loss Method, or similar method, but not addressing data synchronization the accuracy and performance of such methods may be flawed.
SUMMARY OF THE INVENTION
In applying the teachings of '711 and '956 at coal-fired power plants, it has become apparent in developing the methods of this invention that the on-line determination of fuel chemistry and/or fuel heating value is highly sensitivity to effluent measurements, and to their relative consistency in time to each other, that is data with the same time stamp (i.e., the same identifying reference time). The work of this invention has found that data synchronization must be an important consideration when determining fuel chemistry of a fossil-fired thermal system in real-time, and especially as related to the system's operating parameters including effluent measurements. Of these, CO
2
, H
2
O and O
2
measurements, following '711 discussion of how these measurements may be obtained, are the most important. However, the methods as taught herein may be applied to all data involved in determining fuel chemistry, fuel heating value and/or system heat rate including the Input/Loss Method.
Data synchronization is especially important if CO
2
, H
2
O and O
2
measurements have different time delays. An increase in CO
2
, other parameters remaining approximately constant, implies a decrease in effluent O
2
. However, delays in one of these signals, if not corrected, could easily create a situation where both CO
2
and O
2
signals appear to increase or decrease together as would be observed by an uncorrected data acquisition process. The H
2
O is taken herein to be either directly measured at the system's boundary, or otherwise determined. As an example of such sensitivity obtained from a coal-fired power plant, and using methods of '711, consider that a 1.5 minute delay in a CO
2
signal resulting in a 1.0% &Dgr;mole/mole change, results when averaging data over two minutes in a 2.7% change in computed heating value. If mis-diagnosed in computing a change in heat rate (254 &Dgr;Btu/kWh), assuming a typical worth of $30,000/&Dgr;Btu/kWh/year, this 1.0% sensitivity to delays in data collection is worth $7.62 million/year.
When the monitoring a fossil-fired thermal system involves real time analytical modeling of the fuel being burned, and when such modeling relies in part on effluent measurements, this invention recognizes a strong dependency on the synchronization of effluent CO
2
, H
2
O and O
2
measurements. This invention recognizes that effluent CO
2
, H
2
O and O
2
measurements must be consistent in time. As taught by '711 the determination of fuel chemistry, fuel heating value and/or fuel energy flow, dependent principally on effluent CO
2
, H
2
O and O
2
measurements, are not dependent on measured f
Hoenig Gary
Lang Fred D
Barbee Manuel L.
Exergetic Systems LLC
Hoff Marc S.
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