Study of rheological vibration of high-pressure differential string multistage control valve

Abstract

Coal chemical system is faced with high temperature, high pressure difference and large flow rate and other harsh conditions, and the control valve is a key control element in the whole coal chemical system. This study employs experimental methods to validate the numerical model accuracy and utilizes fluid-structure interaction analysis to investigate the vibration characteristics and underlying mechanisms of series multi-stage control valves. Set the inlet pressure to 18.7 MPa, the outlet pressure to 2.9 MPa, and the fluid is water, based on the flow characteristics of the string multi-stage valve under complex working conditions. The vibration characteristics of the valve under five different openings are compared and analyzed, and the resonance response of the intrinsic frequency and modal frequency are studied. The results show that the maximum deformation of the valve reaches 0.011763 mm at 80 % opening; the maximum stress intensity value can reach 199.7Mpa, which has the risk of fluid impact damage; The valve opening directly affects the flow rate and fluid velocity. When the opening is small, the fluid velocity increases, which can easily lead to turbulence and vortex formation, thereby inducing vibrations. Conversely, when the opening is large, the fluid velocity decreases, resulting in smoother flow and reduced vibrations. The vibration damage caused by the tandem multistage regulating valve is mainly due to the influence of vibration positive stress. The location of stress and deformation changes will not change with the change of opening, while the change of opening has a significant effect on the stress value and deformation value. The resonance frequency of the control valve is about 671HZ at low frequency, which has a greater impact on the upper valve body and valve stem. To provide a research basis for the study of vibration and noise reduction of string type multistage control valve.