Methods For Measuring Regenerative Extraction Steam And Exhaust Steam Wetness Of High-pressure Cylinder In Nuclear Steam Turbine

High-pressure cylinder of nuclear steam turbine works in wet steam area. Thewetness and enthalpy of regenerative extraction steam and exhaust steam hasn’t beendetermined accurately, so thermodynamic economic indicators such as relativeinternal efficiency can’t be calculated exactly. In addition, the presence of wetness hasan effect on economy and safety of units. At the same time, peak shaving will be thedevelopment trend of high capacity pressurized water reactor nuclear powergenerating units in future. Therefore, it’s necessary to determine the wetness ofregenerative extraction steam and exhaust steam of high-pressure cylinder accurately.Firstly, this thesis analyzes the characteristics of a nuclear power plant system,and the bigger difference between nuclear power plant system and thermal powerplant system is summarized in this thesis.Moreover, taking the1000MW nuclear turbine as an example, the relationshipbetween main steam flow and regenerative extraction steam flow under differentconditions is analyzed in the thesis with lots of documents which discussing therelationship mentioned before. The relationship in different allowable error ranges isalso given in the thesis. At the same time, the influence on regenerative extractionsteam share is given in the thesis which is caused by the range that deviating from therated condition and the error due to the application of Flugel formula on variablecondition calculations. By high pressure heater corresponding regenerative extractionsteam share under variable conditions, then the ratios of some parameters such as thedrain flow from the separator and the reheater in the main steam flow were calculated.Through the mass and energy balance equations of heat recovery systems and theratio, the wetness and enthalpy of regenerative extraction steam and exhaust steamare determined.Aiming at the characteristic of pressurized water reactor secondary circuit nuclear power generating units, another measurement method is proposed. Bydetermining the steam flow of low-pressure cylinder, we can determine the wetnessand enthalpy of regenerative extraction steam and exhaust steam, which includes thecombination of the use of measured data and reheat steam separator system with themass and energy balance equations of heat recovery systems adding to Frugal formulaof grade group.Finally, two methods mentioned in the thesis are calculated for each condition ofthe wetness and enthalpy of regenerative extraction steam and exhaust steam, basedon the system thermal parameters of domestic representative PWR nuclear power990MW and1000MW generating units. The calculation results show that the newmethod is effective.