Research On Monitoring Technology Of Corrosion Products In The Steam-water Cycle Of UItra-supercritical Power Plant

The electrical power industry of China has developed rapidly since the beginning of the new century,and the proportion of new energy such as hydro power,nuclear power and wind power has increased gradually.However,the lead role of thermal power generation has never changed in China.The traditional thermal power generation technology is developing towards the higher-parameter ultra-supercritical unit technology in response to the call for energy conservation,emission reduction and green energy.With the advantages of low consumption,low carbon and economy,bringing higher requirements to the safety performance of the pipe materials.The corrosion and deposition of corrosion product are becoming an important factor to the safety of the pipeline.Corrosion products in steam-water systems exist in both dissolved and particulate forms.The concentration of the two forms affects the various processes of migration.While the information of dissolved corrosion products concentration and the st particle parameters needs to be monitored by representative samples.Therefore,it is very important to study the condition monitoring such as corrosion products for the safety management of ultra-supercritical units.The important influences of corrosion product concentration and particulate corrosion product particle parameters on migration studies were analyzed.This paper divided equal-state monitoring into equal-state sampling and iso-state detection.The fluent software is used to simulate the three states of the nozzles.The results show that the sampling efficiency of the sampling system in steam mainly depends on the sampling rate and sampling position.,nozzle size and particle parameters.The sampling of the medium is divided into equal state sampling and iso state detection.The fluent software is used to simulate the three types of nozzles.The results show that the sampling efficiency of the sampling system in steam mainly depends on the sampling.At sampling rate,sampling position,nozzle size and particle parameters.In the sampling of the medium is steam,the sampling efficiency depends mainly on the sampling speed.While changing the sampling speed,the particle concentration entering the sampling nozzle inlet section changes.The higher the sampling speed,the larger the particle concentration entering the sampling nozzle.The distance between the sampling nozzle and the pipe is different,and the sampling efficiency also changes.As long as there is a sampling nozzle in the flow field of the pipe,it will interfere with the continuity of the flow field,eliminate the conditions of sampling in the same state,and the longer the distance into the pipe The greater the degree of interference.When sampling at the center of the pipeline,the sampling concentration ratio is close to 1,and at a distance of 0.4R,0.6R,and 0.8R from the wall of the pipeline,the degree of deviation is more semppled.A nozzle with a small diameter interferes with the pipe fluid less than the diameter and has a higher sampling efficiency.With equal-state sampling,particles of various sizes can be taken in equal proportions.Three kinds of particles of 0.5?m,1?m and 2?m were sampled in steam.The results showed that the concentration of corrosion product particles of 2?m was higher when the sampling speed was smaller,and the concentration of corrosion product particles of 0.5?m was higher when the sampling speed was larger.When sampling,all three particles can enter the sampling nozzle in equal proportions.The sampling efficiency mainly depends on the sampling speed.While changing the sampling speed,the particle concentration entering the sampling nozzle inlet section changes.The higher the sampling speed,the larger the particle concentration entering the sampling nozzle.The distance between the sampling nozzle and the pipe is different,and the sampling efficiency also changes.As long as there is a sampling nozzle in the flow field of the pipe,it will interfere with the continuity of the flow field,eliminate the conditions of sampling in the same state,and the longer the distance into the pipe The greater the degree of interference.When sampling at the center of the pipeline,the sampling concentration ratio is close to 1,and at a distance of 0.4R,0.6R,and 0.8R from the wall of the pipeline,the degree of deviation is more sampled.A nozzle with a small diameter interferes with the pipe fluid less than the diameter and has a higher sampling,efficiency.With equal-state sampling,particles of various sizes can be taken in equal proportions.Three kinds of particles of 0.5?m,1?m and 2?m were sampled in steam.The results showed that the concentration of corrosion product particles of 2?m was higher when the sampling speed was smaller,and the concentration of corrosion product particles of 0.5?m was higher when the sampling speed was larger.When sampling,all three particles can enter the sampling nozzle in equal proportions.In view of the problem that the pressure drop of the sampling system is too large and the corrosion products are redeposited,the diameter of the sampling tube and the roughness coefficient of the pipe wall at different temperatures are continuously coupled,and the pipe diameter corresponding to the state detection is obtained under the assumption of a certain allowable minimum pipe length.Combination with roughness.A cross-flow filter is introduced to separate the particulate corrosion product from the dissolved corrosion product,and the particles are introduced into a particle counter for detection.An ultra-supercritical unit corrosion product monitoring system for simultaneously monitoring the information of particulate corrosion products and the concentration of dissolved corrosion products was proposed.