Data processing: generic control systems or specific application – Specific application – apparatus or process – Chemical process control or monitoring system
Reexamination Certificate
1999-05-14
2001-09-11
Gordon, Paul P. (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Chemical process control or monitoring system
C110S191000, C110S347000
Reexamination Certificate
active
06289266
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods of operation of boilers and, more specifically, is directed toward the optimization of operation of coal fired boilers through monitoring and adjustment of fuel and air supplied to individual burners.
2. Description of the Prior Art
It has long been recognized that in connection with numerous industrial activities, including utility power plants that public policy dictates that attention be directed toward the impact such activities have on the environment, both near term and long term. In the United States, under both federal law and state laws, as well as related regulations and judicial interpretations, large bodies of legal requirements have evolved.
Within the limits imposed by environmental considerations, there is a strong desire to lower production costs by enhancing boiler efficiency. For example, in fossil burning electric utility plants, there is a need to provide for improvement and performance of coal fired boilers.
It has been known to employ optimization software in an effort to control the operation of coal fired boilers remaining at stable load conditions with a view toward enhanced efficiency of performance and comply with environmental requirements.
In spite of the foregoing, there remains a very real and substantial need for improved systems for controlling operation of boilers with focus upon monitoring and controlling the performance of individual burners responsive to load conditions to reduce production costs while complying with environmental requirements.
SUMMARY OF THE INVENTION
The present invention has met the above described need by providing a boiler having a plurality of burners each being monitored in respect of fuel flow and air flow. This information is delivered to and processed by a computer, which may be a microprocessor, which compares the flow rates with a stored model for the boiler and if a predetermined difference exists as to a particular burner, between the data determination and the model an adjustment is made in the air to fuel ratio for that burner. This adjustment may, for example, be made by altering the secondary air flow or the fuel flow.
The method involves monitoring each boiler burner separately and making determinations for controlling the same separately. The method may be employed to minimize NO
x
emissions, minimize loss on ignition and to optimize heat rate.
In a preferred embodiment of the invention pulverized coal is delivered to a burner in a conduit with the primary air serving to transport the coal. The flow rates of the pulverized coal is determined within this conduit and the secondary air flow is determined by separate means. The primary air flow may be determined from the measured fuel flow and secondary air flow or may be measured.
Repeated cycles of monitoring and control of the individual burners with model updates being provided as changes are made in the flow rates all contribute to accomplishing the objectives of the present invention.
It is an object of the present invention to provide a method for enhanced automated control of a boiler which on a burner by burner basis enhances boiler efficiency.
It is a further object of the present invention to provide such a method wherein computerized control permits rapid determinations of the flow conditions to a boiler burner and issuance of control signals where appropriate along with updating of the computer model.
It is another object of the present invention to provide a method of operating a coal fired boiler which will reduce NO
x
emissions.
It is a further object of the present invention to improve efficiency of operation of fossil fuel boilers employed by electricity generating utilities, as well as in other industrial uses.
It is a further object of the present invention to provide such a method which will operate more efficiently under conditions of varying boiler load.
It is another object of the present invention to provide such a method which monitors and controls individual burners.
It is a further object of the present invention to provide such a system which is adapted to control operation of a boiler in the load following mode.
These and other objects of the invention will be more fully understood from the following description of the invention on reference to the illustrations appended hereto.
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patent: 5231939 (1993-08-01), Tanaka et al.
patent: 5611494 (1997-03-01), Williams
patent: 5630368 (1997-05-01), Wagoner et al.
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E Ultramax (The Ultramax Method of Dynamic Optimization).
WDPFII System Overview (Descriptive Bulletin 21-161).
Payson Edward P.
Sendro Daniel V.
Allegheny Power Service Corporation
Eckert Seamans Cherin & Mellott , LLC
Gordon Paul P.
Jenkins David C.
Silverman Arnold B.
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