Decentralized measurement of multi-phase fluid into gas refinery by soft sensor using differential mean value theorem

This article proposed a new technique for the measurement of multi-phase rich gas flow (gas and condensate) in a gas refinery, using soft sensors. The multiphase flow entering a refinery was modeled using a decentralized system, composed of interconnected subsystems. Then, the states of the condensate and gas sub-systems were separately estimated using the Differential Mean Value Theorem (DMVT), converting conditions to linear matrix inequality (LMI), designing a nonlinear observer, and considering the relationship between two subsystems. Using the HYSYS simulator with the real process data, it is found that proposed observer is capable to identify the states with reasonable performance. The states behavior investigated with and without disturbance in the system output and dynamics. As a result, this technique not only can be substituted for the existing system at the gas refinery, but also can be as a backup for available measurement systems.