The Accurate Thermal Performance History Files of Wet Steam Turbine in Nuclear Power Plant

There are significant differences between the nuclear power plant turbine and the coal-fired power plant turbine. So the characterization and monitoring models for the coal-fired power plant turbine can not be reused in the nuclear power plant second loop. The unknown wet steam enthalpy and the characteristic of the turbine flow capacity were the two important obstacles for the nuclear power plant wet steam turbine. Based on the accurately measured test data, the accurate thermal performance history files was constructed using the small error heat balance method and the characteristic flow area (CFA). The accurate thermal performance history files were the base for the performance analysis, variable condition calculation, monitoring and diagnosis. The accurate thermal performance history files of Ling Ao unit 3 showed that the unit performance almost was excellent. But the CFA values and the efficiency indicated that some stages of intermediate pressure cylinder (IPT) had leakage in diaphragm, which decreased the unit output. The characteristic parameters of heat regenerative system and moisture separator reheaters system were almost close to the design values, which denoted that the performance of the two systems was acceptable. But the condenser back pressure was larger than the design values, which suggest that the performance was worse than the design condition.