Development Of A Quantitative Detection Instrument For Oxide Stacking In Austenitic Stainless Steel Tubes

In supercritical and ultra supercritical power plant boiler, austenitic stainless steel pipe are widely used to manufacturesuperheater and reheater, and the pipe has the characteristics of high temperature resistance and better corrosion resistance.When the upperheater and reheater are designed, the time of oxide skin falling off is estimated for five years or longer. However, in the process of actual operation, the bad working environment will speed up the oxidization on the pipe inner surface, and formed the oxide skin.When work environment radically change, such as the stopped and started boiler of annual maintenance, the oxide skin adhered on the inner wall of pipe easily peels off. Then the oxide skin peeled off will accumulate in the pipe elbow of superheater and reheater, and block pipe, even lead to pipe burst.In recent years, the major power plants more and more pay attention to the influence on oxide skin in the pipe for boiler, and invest a lot of money testing the oxide skinevery year, then prevent the economic loss of the machine stopped because of the pipe burst.Now the X-ray flaw detection device is used to nondestructive test the oxidedeposited in the boiler pipe.The testing technology is that the testing speed is slow, testing cost is big, and it can't both economic and safe to evaluate the oxide skin in the pipe. Soan effective nondestructive testing technology is urgent needed to accurately detect the oxide in the pipe of superheater and reheater pipes, and reduce the economic loss of the machine stopped because of the pipe burst.In order to effectively detect theoxidepeeled off are stacked or not in the pipe of power station boiler superheater and reheater, and it is blocked pipe or not, this paper developed a-kind of quantitative testing instrumentation austenitic stainless steel pipe oxide accumulated. on the one hand,the equipment is can quickly and efficiently detect the accumulation conditions of the oxide skin in the power plant boiler austenitic stainless steel pipe, exclude the pipe blasting caused by too muchoxide skin in the stainless steel pipe. On the other hand, through detecting the oxide skin in the stainless steel pipe, the effective data support of the overall oxidation corrosion station on boiler stainless steel pipe can be provided, and realize the safety assessment of the boiler.In the light of the station of the oxide skin blocking pipe, on the basis of in-depth investigation and analysis, through the research of key technology, this paper has the following research:First of all,we research the problem of the austenitic stainless steel pipe in the process of the superheater and reheater, and the technological means of counterparts at home and abroad to solve related problems. For the current technical status and needs, the research content of this paper is made.Secondly, though simulation experiment, we research the correspondence relationship between the stack thickness and detection signal, the graphics display method of the stripped oxide is discussed. Thus,thisarticle provides the technical support to the development of the oxide accumulation quantitative detector.Third, we develop a special sensor, which can be used to detect the thickness of oxide. And design the instrument circuit, including signal amplification, signal collection signal processing and so on. Then a quantitative analysis instrument for the accumulation of oxides in austenitic stainless steel tubes is developed.Fourth, according to the characteristics of the special sensors, combining the actual hardware circuit, we design the functional software of quantitative detection apparatus for oxide accumulation in austenitic stainless steel tubes, and describe the main process of software programming.Fifth, a relationship experiment about Pipe inner oxide stacking, weight, thickness and instrument outcoming signal is done by using the developed instrument in the laboratory environment, and the relationship curves of the voltage value with the Oxidation skin product and oxide thickness are acquired. At the same time, the instrument is calibrated. Then the validity of the instrument is verified by the comparison experiment of Power plant.In summary, this paper has described the development of a quantitative detection apparatus for oxide accumulation in austenitic stainless steel tubes, and a large number of laboratory and field experiments.Practice has proved that quantitative detection apparatus for oxide accumulation in austenitic stainless steel tubes can detect the oxide of boiler superheater and reheater pipe in the amount of fast, which were shown in graphics.This instrument can provide a fast, convenient detection method for power plant boiler superheater and reheater pipe, which will greatly save the cost and time of detection. With the wide spread of this instrument, it will produce great social benefits in terms of the detection of the power plant boiler superheater and reheater pipe.