Specify Control scheme for a Cryogenic Stripper

Please see the attached file for the fully formatted problem(s).



S.17. Sketch a control scheme for the cryogenic stripper shown below that is used for removing small amounts of propane from natural gas.

[DIAGRAM]

(a) Cooling-water valve V-I is manipulated to control the gas temperature leavü4 the cooler.
(b) Valve V-2 controls a temperature on tray 15 in the stripper.
(c) Valve V-3 controls the total flow rate of gas into the compressor.
(d) Valve V-4 controls the temperature of the propane bottoms product leaving óe unit.
(e) Valve V-5 controls the column base level.
(f) Valve V-6 controls the liquid level in tank 1.
(g) Valve V-i controls the speed of the expander turbine.
(h) A “valve position controller” is used to keep valve V-7 nearly wide open adjusting the setpoint of the expander speed controller.
(i) A pressure controller opens valve V-8 if the pressure in tank 1 gets too high.
(j) Valve V-9 controls tank 2 level.
(k) Valve V- 10 controls tank 2 pressure.
(1) Valve V-il controls the pressure in the stripper.
(m) If the pressure in the stripper gets too high, an override controller pinches bc valves V-2 and V-3.