Detection And Treatment Of Pipe Burst In Supercritical Power Plant

Power resources are indispensable energy for our daily life.In recent years,the energy demand is getting tighter and the power demand is growing.The power plant equipment is developing towards large capacity and high parameter supercritical units.At this time,the technical requirements for power equipment and safety need higher requirements.At present,one of the common problems faced by supercritical units is the pipe burst caused by oxide scale.The oxide scale peeling off from the pipe cause the blockage or burst of the pipe and the erosion of the steam turbine blades.The scale problem has seriously hampered the safe operation of supercritical units.With the development of sensor technology,a large number of process variable data have been accumulated in the field,so fault detection and diagnosis based on data have drawn more and more attention.In this thesis,the super heater pipes of the Yanshan Lake power plant in Chaoyang City are taken as the research background.We study the formation mechanism of oxide scale generating,peeling off and blockage.Based on this,the fault diagnosis is carried out based on the on-site process data.In this thesis,we use Fast Kernel Independence Component Analysis(FastKICA)based on the Hilbert-Schmidt Independence Criteria to realize fault diagnosis.On the basis of fault diagnosis,we proposed chemical cleaning scheme of the oxide scale.The main work done in the article includes the following aspects:(1)The formation mechanism of oxide scale in the super heater tube of supercritical power station,the cause of spalling and the analysis of the related factors of squib failure reveal the formation mechanism of oxide scale and the growth process,the composition of oxide scale and the layered structure,To establish a mathematical model of oxide thickness growth.(2)The Hilbert-Schmidt independence criterion is used to measure the independence of estimated nonlinear elements.the independent element extraction is completed,so as to realize the pipe burst detection based on FastKICA.When applied to squib monitoring,compared with traditional KICA,it can effectively improve the accuracy of non-Gaussian process prediction and reduce the false alarm rate and omission alarm rate.(3)On the basis of fault diagnosis,we design chemical cleaning scheme of the oxide scale and set up the mathematical model of the chemical reaction rate of hydrochloric acid.Based on the growth model of the oxide scale,under ideal conditions,we study the cleaning time based on a certain temperature and concentration,and verified by the test,want to provide some ideas for the treatment of oxide scale.With the widespread application of supercritical power plant boilers in the world,the peeling off of oxide scale during long-term operation is a common problem.How to apply the research theory and technical methods to accurately determine the oxide scale conditions of super heater tubes,strengthening operational control,reducing overheating burst accident,and timely measures to deal with the formation of the oxide scale,and further select the effective features,effective fault diagnosis,which is our direction to continue our efforts,I hope the study can play a guiding role in the safe operation of the unit.