Research On Charavteristics Of A New Pilot-operated Globe Valve In Vertical Pipeline

Globe valves with traditional driving device have disadvantages of large actuator, high energy consumption and slow response. As a new type of globe valve, the pilot-operated globe valve has remarkable effect on the improvement of driving mode and opening/closing characteristics. Because the installation of the valve is restricted by the pipeline layout and the demand of fluid control, a new structure of pilot-operated globe valve which functions well in vertical pipeline is put forward in this paper. However, the basic working principle, the force condition of motion components and the opening/closing characteristics hasn’t been studied systematically. Thus in this paper,3-D numerical model of the pilot-operated globe valve was established basing on CFD methods to study on the flow field distribution, dynamic characteristics, open action and the chosen of spring stiffness of the valve. Main contents and results of this research are as follows:1.3-D geometric model of the pilot-operated globe valve in vertical pipeline was established, discrete scheme, solution of discrete equation, boundary condition and physical properties of liquid media was determined. Numerical research on the valve was taken basing on k-ε turbulence model.2. The relationship between the pressure difference which plays the role of main motive power during the opening process of the valve and the inlet velocity, the outlet static pressure and the orifice diameter was analyzed. On this basis, the quantitative relationship between pressure difference and inlet velocity and orifice diameter was established to provide guidance for the accumulation of dynamic power and the chosen of structure parameters of the valve in different working conditions.3. Through the steady numerical simulation on valves with different valve opening, the pressure field distribution and the motive power under different valve opening was studied and the opening process of the valve was discussed preliminarily. The motion equation of the valve core was established to compile UDF program to determine the motion of the valve core, on this basis, transient simulation on opening process of the valve was realized. The influence of different opening mode and spring stiffness on opening characteristics of the valve was studied to discuss the selection method of spring stiffness basing on transient simulation results.4. The force equilibrium equation of the valve core was established, combining the conclusion of transient simulation and calculation formula of pressure difference, the selection formula of spring stiffness was obtained. The accuracy and applicability of the formula was verified under different boundary condition, orifice diameter of the valve core with numerical simulation. The selection formula provides a system and effective methods on the chosen of spring stiffness.Results of this paper have important guiding significance and academic value for the structure selection and engineering applications of the pilot-operated globe valve in vertical pipeline.