Method for detecting internal leakage of valve of thermodynamic system in power plant

Abstract

The invention relates to a method for detecting internal leakage of a valve of a thermodynamic system in a power plant. The method comprises the following steps of: measuring outer wall temperatures of pipe segments in front of and at the back of the valve and ambient temperatures; calculating to obtain quantities of heat emission of the pipe; calculating to obtain flow velocity and flow rate of a fluid inside the pipe; and performing quantitative economic analysis on the flow rate of the fluid inside the pipe. When the leakage of working medium of the valve occurs, the pipe wall temperature rises due to heat emission. The heat transfer process tends to be stable after a certain time period if the leakage of the valve keeps unchanged, and the heat emission and the pipe wall temperatures maintain a certain value. When the calculation control volume used is short enough, the heat transfer quantities Q4 and Q5 in the longitudinal direction of the pipe are minimal and can be neglected in calculation. As a result, the heat emission of the pipe wall and the heat emission of the heat-insulating layer are close to the heat transfer of a single-layer homogenous cylindrical wall. The detection method is significant in determining inspection and repair according to the running state of the valve in the power plant, reducing internal leakage of working media of the valve in the power plant, reducing power and coal consumptions during operation and increasing operating economy.

Description

technical field [0001] The invention relates to the technical field of condition maintenance and economical operation of power plants, and in particular to a method for detecting internal leakage of valves in thermal systems of power plants. At the same time, it plays an important role in reducing the leakage flow of valve working fluid in power plants, reducing coal consumption in operation and power supply, and improving operation economy. Background technique [0002] For leak detection, ultrasonic leak detectors are usually used. Ultrasonic leak detector is a leak detector with ultrasonic detection method, which can check the leakage of air, gas, steam and liquid pipelines and various equipment. If used in conjunction with the attached ultrasonic generator, it can also check the sealing status of refrigerators, sealed containers, air conditioning systems, tires, compressors, and various infusion pipelines. It is a powerful tool for improving the environment and saving e...

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Problems solved by technology

[0005] Domestic power plants mainly use manual monitoring to make qualitative judgments on internal leakage of valves in thermal systems, and the flow rate of working fluid leaking from valves cannot be obtained.

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