Research On Technologies Of Supercritical Unit Superheater Oxide Chemical Cleaning

In recent years, the thermal power plant for superheater oxide skin caused by over temperature and tube explosion and the turbine blade erosion problem more and more serious and widespread, the research and development of superheater oxide chemical cleaning technology is one of the effective ways to solve this problem.Superheater chemical cleaning than the chemical cleaning of boiler has a higher, more complex technical difficulty, from the point of view of corrosion at characteristics of the following two aspects have increased the difficulty of corrosion control. First, the superheater tube scale, differences in microstructure, scales dense and need to use higher cleaning medium concentration and longer cleaning time, even the second or third cleaning, thus increasing the difficulty of control the corrosion rate and corrosion of the total, especially ferrite steel body of uniform corrosion and pitting. Second, superheater material complex, containing ferritic steel and austenitic stainless steel, such as 12CrlMoV, T22, T91 and TP347 are such as, to control chemical cleaning in the process of metal corrosion, usually to acid corrosion inhibitor is added, but slow inhibitor on different metal material corrosion inhibition effect are different. Therefore, the corrosion of chemical cleaning process in all the metal materials control more difficult. In addition, the current process of superheater chemical cleaning is still use the traditional weight-loss method to evaluate the corrosion rate of materials in chemical cleaning process, but the method can only be obtained after the chemical cleaning the whole cleaning process of the average corrosion rate, not in real time on cleaning process of corrosion monitoring.The according to the principle of corrosion electrochemistry developed for superheater chemical cleaning environment system of on-line corrosion monitoring and corrosion monitoring electrode, and the reliability of on-line corrosion monitoring system is verified through experiments of corrosion. Through the field oxide skin shedding, tube explosion case investigation and study and the actual tube like oxide skin for experimental study of analysis, different materials superheater oxidation peel rules, and to analyze the influence of the thickness of oxide scale on the life of the unit and the efficiency of boiler, and then determine the superheater oxide chemical cleaning, to instruct the power plants according to the superheater oxide selected chemical cleaning time.