Question: Control of the flash process analyzed in this chapter involved partial control. All six components in both product streams would influence product quality and profit, but only one dominant variable, mole fraction ethane in the liquid, was controlled. (a) Discuss the final steady-state deviations of all compositions from their initial steady-state values for the control system developed in this chap ter. Consider each of the disturbances in the control design form separately.
(b) An alternative dominant variable, the flash temperature (Te) could have been selected rather than liquid mole fraction ethane. Discuss the advantages and disadvantages of Teas a dominant variable (not reset by AO.
(c) Discuss process and control modifications needed to control the per cent propane in the vapor product in addition to all controlled variables in the original control design.