Design Of On Line Monitoring Wetness Fraction System In Steam Turbine Of Nuclear Power Plant

In modern nuclear power plant,all the stages in nuclear steam turbine operate in wet steam region,the drain erosion on blade is caused by wetness fraction,the operation safety of steam turbine is threaten by the blade erosion,At the same time,the blade erosion increases the flow losses in flow passage,which decreases the efficiency of steam turbine.Further more,the moisture loss decreases the efficiency of steam turbine too.so the wetness fraction have a great influence on the operation of steam turbine about safety and efficiency.Many methods of measuring wetness fraction is analyed and compared in this thesis,the Double-region-heating method is chosen as the basis of monitoring the wetness fractin on line in exhaust of steam turbine,also designed monitoring wetness online based Double-region-heating method. Double-region-heating adopts heating at exterior of the tube and includes evaporative section and superheated section..The saturate steam is heated to superheated steam with higher superheate degree.By measuring the temperature and press in the entrance of evaporation section and exit of superheated section,we can get the humidity according to formula.At the same time,superheated section is uesed to measure the steam flux instead of equipments,the system is simpfied.Control unit and collect data unit of this monitoring system is based 8051,and expaned electric circuit.including platinum resistance PT100,pressure translator,AD transformer,and heating electric circuit. This thesis also analyed system error, such as platinum resistance of nonlinear and heat loss caused by factors such as measurement error, and done a software error against the amendment, to some extent, improve the measurement accuracy.The system's software design using C51 language, to Keil platform for the development, design and realization of data collection, data storage, heating control and data communication functions.This thesis adopted fuzzy math and statistical theory to double-region-heat measuring system.,From data test and verify,the arithmetic recursive estimation and batch estimation data fusion algorithm are confirmed is correct.