| The control valve is widely used in thermal power, nuclear, chemical and other fluid control occasions, it is the indispensable and important component in materials or energy supply system. Steel mills using waste gas in combined cycle power project, steel mills use the nominal diameter≥200mm of large control valve to control pressure of the mixed gas. With the long time running, the natural aging of the equipment, human damage and other reasons, the fault of control valve occurs frequently, it will lead to the shutdown of power generation equipment, and it also caused a huge economic losses.Therefore, large pressure control valve dynamic analysis and fault diagnosis becomes a key technical problem of the combined cycle power plants. The main research contents of this paper are as follows.The related problem of the dynamic performance and fault detection for large-scale pressure control valve were studied. The problem of needing to solve for vibration control, energy conservation, noise control, fault detection and localization were discussed, and pointed out that according to the structural characteristics to research vibration reduction, according to the internal flow field to research energy saving and noise reduction, and according to the dynamic characteristics to study the fault detection and localizationDynamic analysis and fault detection theory of valve were introduced. The fault detection mechanism of the leakage and blockage were studied, mass flow functionand the mathematical model of mixed gas mass flow was established. In fault location, the mass flow gradient was introduced, and the fault location mechanism of the leakage and blockage were studied, and it provided a theoretical basis for the further study of the later chapters.The dynamic analysis and optimization of large-scale pressure control valve were researched. The3D solid model of large-scale pressure control valve was established. The modal analysis results showed, over all, with opening increasing, frequency was reduced. On this basis, the expansion of semi-active variable stiffness was proposed. Then the flow model was established, the flow characteristics, pressure-flow and opening-pressure properties were studied by mixed gas. The causes of valve internal flow field whirlpool were analyzed. Through the optimization, the whirlpool of seat was eliminated, and the outlet of the whirlpool was reduced. Proposing variable throttling surface Circuitous path for noise reduction by studying noise control mechanism, and the influence of the size and number of the porous sleeve for noise reduction were analyzed. The results showed that it not only eliminated the large whirlpool in the bottom of the valve outlet, reduced the swirl of the left side of the cavity, it was more apparent than common porous sleeve in noise reduction.The dynamic characteristics and leakage fault detection and location method of the control valve were researched. The3D model of valve inlet leakage, valve outlet leakage, valve stem leakage, valve cover leakage and their flow models were established. The modal analysis and flow analysis of the different leakage faults were studied. The results showed that the leakage fault reduced the order of the natural frequency, flow characteristics curve of inlet leakage and outlet leakage were slight concave than trouble-free, quick opening were weakened. The leakage point flow characteristics were proposed by leakage fault, and pointed out that flow characteristic curve of inlet leakage point and outlet leakage point were similar to the decline of linear curve. The valve stem leakage point and valve cover leakage point were similar to the decline of sine curve. In order to ensure the stable after pressure, the valve should be as far as possible maximize the before pressure. The influence of the leak port size and number for differential pressure-flow of valve, and leakage faults for noise distribution were researched. According to the dynamic characteristics of the valve leakage, leakage fault detection and localization were studied. The method of mass flow leak detection and double mass flow leak location were proposed. The leak location table was made through simulation experiments.The dynamic characteristics and blockage fault detection and location method of the control valve were researched. The three-dimensional model of valve inlet blockage, valve outlet blockage and valve body blockage were established. The modal analysis showed that the valve inlet blockage and valve body blockage reduced the natural frequency, and valve outlet blockage increased the natural frequency of valve system. On the basis of three-dimensional solid model, the blockage fault flow models were established. The internal flow fields were analyzed. The results showed that flow characteristics curve of blockage were slight convex, quick opening were raised and the flow reduced. In order to achieve a predetermined flow rate should to increase opening or pressure. The influence of the block size and number for flow field were researched, got the influence of outlet blockage was bigger than inlet blockage in flow field, the flow sharply reduced with obstruction increased. The influences of the blockage faults for noise distribution were researched. According to the dynamic characteristics of the valve blockage, blockage fault detection and localization were studied. The method of mass flow leak detection and double mass flow block location were also proposed. The block location table was made through simulation experiments.The experiment system of dynamic performance and mass flow detection were constructed. Modal experiments and mass flow detection experiments were done, and valve fault detection system was designed. Through the modal experiment, the accuracy and credibility of the control valve modeling and simulation data for the previous section were verified. Through the mass flow detection experiments, they showed that can accurately reflected and monitored the change of the mass flow for the system, and the feasibility for fault diagnosis system.
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