High Pressure Dynamic Seal for Plunger Pumps With Pressures Above 35 KPSI

The sealing of moving parts under high pressure is one of the most demanding tasks in high pressure technology. For the design of the sealing elements all influencing factors such as mechanical deflections, motion speeds and fluid properties under high pressure must be fully understood and considered. Developments in both materials and manufacturing methods provide new possibilities for the design of sealing systems. This technical paper describes typical sealing issues of dynamic seals at pressures in excess of 35 kpsi with emphasis on plunger seals of high pressure reciprocating pumps. Different plunger sealing concepts are compared and their technical characteristics are analyzed. A new friction-free metallic sealing system is presented and the performance of the sealing system is illustrated by means of numerical simulations considering the fluid-structure interaction and operational experience. The paper further summarizes investigations carried out on changes of fluid properties due to high pressure and shows how this influences the sealing system and the performance of high pressure pumps. Based on this data recommendations are given to prevent problems due to crystallization or polymerization which typically arises in high pressure co-monomer feed systems. The progress in sealing technology reveals new perspectives for high pressure applications in LDPE production plants.