Electricity: measuring and testing – Determining nonelectric properties by measuring electric...
Reexamination Certificate
1999-05-18
2001-09-11
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Determining nonelectric properties by measuring electric...
C324S693000, C324S700000, C324S715000, C324S718000, C324S071200
Reexamination Certificate
active
06288528
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and system for evaluating a condition of a combustion vessel and, more particularly to a method and system for evaluating a condition of a combustion vessel as a function of a detected electrical characteristic of the combustion vessel.
One condition of a combustion vessel which is often of interest is the accumulation of combustion related material such as ash based combustion byproduct on deposition exposed surfaces of the vessel. Another related condition which is also often of interest is the loss or wastage of such deposition exposed surfaces or other structure of the combustion vessel which results from the relatively high temperatures and other process conditions often present in combustion vessels such as fossil fuel-fired furnaces.
The fouling of heat transfer surfaces due to the deposition of slag and other constituents of the fly ash generated during fossil fuel combustion is a problem which operators of fossil fuel fired furnaces continuously face. The cumulative reduction in the heat transfer coefficients on the deposition exposed surfaces of the furnace changes the heat distribution within the furnace and reduces the overall furnace efficiency. Further fouling of these surfaces eventually impairs the efficiency of any power generating unit comprising the furnace. Moreover, the accumulation of slag or other deposits on the surfaces frequently accelerates the corrosion of the metal which typically comprises such surfaces.
Several methods have been proposed for evaluating conditions such as the two aforementioned conditions in combustion vessels. U.S. Pat. No. 4,176,554 discloses a method for evaluating a temperature profile of a kiln which includes the steps of obtaining a temperature profile of the kiln based upon temperature information provided by a plurality of thermocouples. U.S. Pat. No. 5,615,953 discloses a system for obtaining a temperature profile of a bank of tubes of a fossil fuel-fired boiler in order to determine the amount of build up on the tubes. A series of temperature readings are taken at intervals along the length of an extension arm, such as a sootblower lance, which is extended near the tube banks of a boiler. The temperature readings are integrated to form a temperature profile from which conclusions may be drawn concerning the accumulation of the tube banks of the boiler.
Although there has been demonstrated the desirability of a method and a system for reliably monitoring selected conditions of a combustion vessel, such a method and system has not yet been proposed. Accordingly, the need still exists for a method and a system for reliably monitoring selected conditions of a combustion vessel.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a method for reliably monitoring selected conditions of a combustion vessel.
It is another object of the present invention to provide a system for reliably monitoring selected conditions of a combustion vessel.
According to one aspect of the present invention, there is provided a method for evaluating a location of interest of a combustion vessel. The method preferably comprises the steps of imposing a current on an electrical network, the electrical network having at least one electrode and being situated relative to the combustion vessel such that properties of the electrical network are influenced by the operation of the combustion vessel. The method further preferably comprises the step of detecting at least one characteristic of the electrical network during the step of imposing a current on the electrical network. The method additionally includes the step of evaluating a condition of the combustion vessel based upon the at least one detected characteristic of the electrical network.
According to one variation of this aspect of the present invention, a fossil fuel is combusted during the combustion process in the combustion vessel and the step of evaluating a condition of the combustion vessel surface includes evaluating the at least one detected characteristic of the electrical network as an indicator of a characteristic of a surface of the combustion vessel. In a further refinement of this one variation, in the event that the material released during the combustion process is ash based combustion byproduct, the step of evaluating the at least one detected characteristic of the electrical network as an indicator of a characteristic of the surface of the combustion vessel surface includes evaluating the at least one detected characteristic of the electrical network as an indicator of a reduction of heat flux.
In yet another feature of this one variation of the above noted method of the present invention, the step of evaluating the at least one detected characteristic of the electrical network as an indicator of the reduction of heat flux includes evaluating a detected resistance value in the electrical network which is relatively greater than a baseline resistance value existing at a baseline time prior to the imposition of a current on the electrical network during the step of imposing of a current on the electrical network as an indicator that the reduction of heat flux is different than the heat flux at the baseline time.
According to another aspect of the present invention, there is provided a system for evaluating a condition of a surface of a combustion vessel exposed to deposition thereon of a material released during a combustion of a fuel in the combustion vessel during a combustion process comprising means for imposing a current on an electrical network having at least one electrode and means for detecting at least one characteristic of the electrical network during the step of imposing a current on the electrical network. The system also includes means for evaluating a condition of the deposition exposed surface based upon the at least one detected characteristic of the electrical network.
In the event that the combustion vessel is operable to combust a fossil fuel during the combustion process, the system preferably includes, in one variation thereof, means for evaluating a condition of the combustion vessel surface which is operable to evaluate the at least one detected characteristic of the electrical network as an indicator of a characteristic of the deposition on the combustion vessel surface. Additionally, if the material released during the combustion process is ash based combustion byproduct, the means for evaluating the at least one detected characteristic of the electrical network as an indicator of a characteristic of the deposition on the combustion vessel surface is, in one variation thereof operable to evaluate the at least one detected characteristic of the electrical network as an indicator of the reduction of heat flux.
A further variation of the system preferably includes the feature that the means for evaluating the at least one detected characteristic of the electrical network as an indicator of the reduction of heat flux is operable to evaluate a detected resistance value in the electrical network which is different than a baseline resistance value existing at a baseline time prior to the imposition of a current on the electrical network while a current is imposed on the electrical network as an indicator that the depth of deposition on the combustion vessel surface is relatively greater than the depth of deposition at the baseline time. Furthermore, the means for detecting, in this variation of the system, is preferably operable to detect a resistance value and the means for evaluating includes means for comparing the at least one detected characteristic with at least one predetermined resistance value.
According to a further aspect of the present invention, there is provided a method for iteratively imposing, during respective current imposing intervals, a current on an electrical network arranged relative to a combustion vessel and iteratively detecting a respective property of the electrical network such as, for example, a resistance or a voltage value of the elect
Goodstine Stephen L.
Simon Jonathan S.
Alstom Power Inc.
Brown Glenn W.
Warnock Russell W.
LandOfFree
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