METODO PER PREVEDERE LA TRANSIZIONE OTTIMALE TRA UN FUNZIONAMENTO A PRESSIONE COSTANTE E UN FUNZIONAMENTO A PRESSIONE VARIABILE

摘要

A method for improving operational efficiency of a partial-arc steam turbine power plant during power output variations by dynamically adjusting valve point values during turbine operation. Impulse chamber pressure at each of a plurality of valve points is first determined during operation of the steam turbine at constant pressure. For each adjacent pair of valve points, an optimum constant pressure transition point pressure for transitioning from one to the other of the sliding pressure mode and constant pressure mode is then computed. The optimum constant pressure transition point pressure for each pair of valve points is converted to a corresponding percentage of the pressure difference between the adjacent pairs of valve points. The impulse chamber pressure at each valve point is then used to calculate a corresponding impulse chamber pressure for transitioning from the one mode to the other mode based upon the percentage pressure difference. The calculated impulse chamber pressures for transitioning are compared to measured values of impulse chamber pressure and the system force transition from one of the modes to the other mode when the measured value is substantially equal to the calculated transition pressure.