Theoretical And Experimental Research On The Performance Of Flexible Disc

In this thesis, a new type of flexible disc technology which has been presented by literature [18] was mainly studied, and a detailed theoretical study and experimental study about the original disc(hereinafter referred to as rigid disc) of safety valve and the replacement of a new type of flexible disc were done. In the low-pressure environment at room temperature, the flexible disc's sealing performance, stiffness, open, discharge and other performance parameters were compared with rigid disc's, in order to study the performance characteristics of flexible disc.Theory section: through large-scale numerical analysis software ANSYS the finite element model of rigid disc and flexible disc were created, and the contact analysis at the sealing surface of disc were done, the contact pressure distribution and contact state at the sealing surface of disc under different media pressure were obtained, and a qualitative evaluation of the sealing performance of the rigid disc and flexible disc was done. The conclusions are as follows: 1) compared to a rigid disc, under the same spring preload the flexible disc can receive bigger contact pressure. 2)It is beneficial to reduce stiffness of disc appropriately for the sealing of safety valve.Experimental part: 1) safety valve stiffness test system design: a safety valve stiffness testing system was designed to measure the relations between the deformation of safety valve inner system and spring preload by experiment. Obtaining the performance parameters of stiffness and flexibility of spring, lift sensor, rigid disc, flexible disc respectively; 2)The static properties of lift sensor calibration experiment system was designed to evaluate the basic performance indicators of lift sensor by experiment, and the linear relationship between the set pressure of safety valve and the lift sensor output strain was got. The difference of the set pressure of safety valve with different structure and stiffness disc was studied by comparing the calibration relationship between the set pressure of safety valve and the lift sensor output strain. 3) A safety valve discharge detection system was set up to simulate safety valve discharge process. Through experiment,the change curve of output signal of lift sensor in the safety valve experimental model with different structure and stiffness disc was got in the entire process of open, discharge and back seat. And the lift sensor output signal was as a standard to compare the performance differences of rigid disc and flexible disc. The completed field tests show that the new type flexible disc also can open quickly , discharge stably, and reseat timely and effective under medium pressure comparing with the rigid disc. It also shows the new type flexible disc is fully capable to satisfy the basic performance requirements of the disc of safety valve.The research on comparing the performance parameters of flexible disc and rigid disc is of great significance for the reconstruction and design of safety valve disc.