Simulation of Pressure Transients Due to Valve Chattering in a Heat Transport Circuit of a Process Plant

Abstract

‘Pressure Transient’ occurs in a pipe network when the liquid flow rate in the system undergoes sudden changes. Valve chattering is one such phenomenon in which the flow resistance of the valve and consequently of the network varies continuously thereby causing flow fluctuations in the system. Although enough literature is available on pressure transients and valve chattering individually, there exists only limited literature dealing with the pressure surge due to valve chattering events. Hence, in the present work, an inhouse developed code (PTAC) based on method of characteristics (MOC) has been deployed to study the pressure transients and flow fluctuations due to valve chattering in the piping network of a typical heat transport system in a process plant. Generally, such systems are made up of multiple parallel paths for heat exchangers to ensure high availability of the system in case any of the components in one branch like heat exchanger, valves, etc. become faulty. The system considered in the present study consists of two parallel paths for heat exchange. Valves are located at the entry and the exit of the two heat exchangers installed in parallel. Sinusoidal as well as aperiodic chattering of valves have been studied. The study reveals that both synchronous and asynchronous chatterings of valves need to be considered to obtain the possible pressure peaking at various locations in a piping network with several valves. The study also found that simulating a system for sinusoidal valve chattering with the highest possible frequency yields conservative estimates of pressure loading as compared to aperiodic valve chattering. The resulting estimates of pressure transient can be adopted by the designer for design of the system components, piping and associated supports.