Intelligent Rotary Control Valve
During recent decades, rotary control valves have encroached upon the traditional territory of the linear globe valve in the petrochemical industry. Eccentric plug valves in particular have established a firmfoothold in petrochemical applications. Ever increasing emphasis on environmental issues hasmeant that petrochemical companies are paying increased attention to emissions coming fromcontrol valves.This trend hasmade rotary valvesmore attractive because rotary valves typically have lower gland emissions than globe valves. In addition to low emissions, eccentric plug valves have proved to be suitable for numerous applications.Typical applications and opportunities, including their uses in the petrochemical industry, are considered.
Apart fromversatility, themost important task of a control valve is to track the setpoint as closely as possible. In order to achieve loop performance, the control valvemust performwell.This requires a high performance control valve. A novelmethod of studying control valve performance,based on a well-known step sequence test, is introduced.
A reliable, long-life valve solution requires careful valve selection and sizing. Factors ranging fromvalve sizing to maintenance are considered.Valve controllability in installed conditions is also studied.An innovative‘valve diamond’, used to visualize control valve performance and evaluate valve problems, is introduced.The key component in maintaining loop performance is the smart positioner with diagnostic features.Diagnostic and devicemanagement can be handled in separate assetmanagement software or even be integrated into the control system.An example of assetmanagement software,based on open FDT/DTM technology, is presented.
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