A FLEXIBLE ON-LINE MONITORING METHOD OF THE EXHAUST STEAM DRYNESS AND THE OPTIMAL INITIAL STEAM PRESSURE IN STEAM TURBINE

With the development of information and computer technology, it is possible to monitor and analyze on-line features of large steam turbine-generator units. Under premise of guaranteeing the unit operating safely, make the unit maintaining at optimal operating mode, thus maximally reduces the coal consumption is the practical request of market economy to the electricity generation enterprises. The choice operating mode is an important topic relates to the security and economic performance of unit. Base on the analyses of those existed calculation methods for turbine varying condition, we give a sequential varying condition calculation that starts with steam extraction of the finial stage or the second final stage (superheated steam condition). According to the initially assumed final stage flow, and the thermodynamic parameters before the final stage, also the backpressure, we can distinguish the flow patterns of the stage by a discriminant criteria. Then we can conduct a stage varying condition calculation of primary stage in sequence from the front final stage parameter, so the new exhaust steam enthalpy and the heat consumption rate can be got. So the precise heat consumption rate and the exhaust enthalpy can be got easily. Furthermore, with the varying condition calculation based on this method, the mathematical model is built for selecting the optimal initial pressure of the coal-fired power unit, with the method of systemic analysis for the first time. That proposed a new method to optimize operation of the thermal power unit.