Patent ID: 7689515

Claim:
A method of evaluating a power plant having a life based on operating the power plant within an allowable chemical exposure range, the method comprising: identifying a projected future period of operation exceeding the allowable chemical exposure range of the power plant; using power plant monitoring equipment, determining a remaining life of the power plant based on the period of operation exceeding the allowable chemical exposure range and assuming continued operation of the power plant within the allowable chemical exposure range; comparing an economic gain achieved by operating the power plant with the projected future period of operation exceeding the allowable chemical exposure range with an economic loss resulting from the remaining life of the power plant being shorter than a design life of the power plant due to the projected future period of operation exceeding the allowable range using the power plant monitoring equipment; and after said comparing, intentionally continuing operation of the power plant for the projected future period of operation upon determining that the economic gain achieved by operating the power plant with the projected future period of operation exceeding the allowable chemical exposure range is greater than an economic loss resulting from the remaining life of the power plant being shorter than a design life of the power plant due to the projected future period of operation exceeding the allowable range; wherein the comparing comprises using formula (I) to determine the allowable chemical exposure range: A t = ∑ i = 1 h ⁢ e i ⁡ ( n - i ) + ∑ i = h c ⁢ e i ⁡ ( n - i ) + ∑ j = 1 m ⁢ ⁢ ∑ i = c n ⁢ a j ⁡ ( n - i ) ; ( I ) and thereafter using the determined allowable chemical exposure range in formula (I) to determine the remaining life of the power plant: A r = A t - ∑ i = 1 c ⁢ e i + ∑ i = c h ⁢ e i ; ( II ) wherein A t is a total allowable exposure over a design life, wherein A r is a total remaining life of the power plant, e i is an exposure for a given year i, h represents a number of years for which historical data was gathered, c is a time in years of an exposure to abnormal chemistry, n is a remaining life of the power plant in years, i is an index for design years, m is a number of Action Levels for a contaminant, j is an index for a number of Action Levels, and a j is an annual allowed exposure in Action Level/in concentration.