Steam Turbine Humidity Examination Based On CCD Technology Application Research

Steam turbine is one of the most important prime motors，with the changes in workingconditions during the operation, the wet steam generated in the flow process, the wet steamhas a very important impact on the safety and efficiency of the turbine. It will not only lead tothe blades of the turbine water erosion, and even lead to the occurrence of blade fracture,affecting the entire power plant safety and economy. Therefore, it is very important to studythe low-pressure turbine cylinder steam humidity.This thesis focuses on the Mie scattering theory and combining with CCD （ChargeCoupled Devices）measurement technology to set test bench. We analyzed data from thepower plant by using method of the numerical simulation to obtain a method for humiditydetection which is simple and rapid, used to the humidity examination instrument in steamturbine low pressure cylinder suction pipe internal steam humidity make preliminary, toimprove application efficiency and economic practicality by CCD detection experimentplatform.Specific research contents are as follows:We took the low pressure cylinder of steam turbine which the type of N310-16.7/537/537in power plant as an example, by using the Fluent software platform, using mixed multiphaseflow model for numerical simulation of the NO.7pipeline of steam extraction, to analysispipeline internal wet steam flows.It combined with enthalpy-entropy diagram, and used the fitting formula, determined thestate of each point within the steam of the steam extraction pipeline, and pipeline had beenobtained at various points within the dry degree of value. Through the analysis found thatwhen the turbine working in more than75%load, internal enthalpy of the steam extractionpipeline would be greater than the enthalpy of saturated steam, so it did not need the humidityexamination, either the pipeline internal pressure below59.33kPa, or need the humidityexamination. This conclusion showed that using CCD to steam turbine when the humidityexamination need the steam extraction for each of the steam turbine pipeline, reduces theworkload and eliminating the blindness of humidity examination things.This experiment based on the CCD laser scattering theory, created a kind of measuring internal wet steam turbine experiment device. The wet steam simulation environment can beeasily carried out the experiment under different working conditions. Humidity examinationinstrument based on CCD data detected with the method of numerical simulation to establishthe working condition parameters of simulation test data, and calculated the workingcondition of each simulation humidity value of the parameter. Found that the maximum errorcondition, it measured dryness average of98.89%, and the simulated calculation result was98.53%, the absolute error was0.36%, so the feasibility of this method was verified.