* Nonsharp separation of propane, isobutane and n-butane
* Aggarwal and Floudas (1990).

* A, B, C denote propane, isobutane and n-butane respectively
* Fi denotes the flowrate of stream i (kgmol/h) 
* xji denotes the mole fraction of component j in stream i
* Refer to Figure 5.5 in the test problem collection.

VARIABLES
	 F1  
	 F2  
	 F3  
	 F4  
	 F5  
	 F6  
	 F7  
	 F8  
	 F9  
	 F10  
	 F11  
	 F12  
	 F13  
	 F14  
	 F15  
	 F16  
	 F17  
	 F18  
	 xC8  
	 xB8  
	 xA12  
	 xB12  
     objval    Automatically generated objective function variable;

FREE VARIABLES    objval;


EQUATIONS
	 g1  
	 g2  
	 g3
	 g4  
	 g5  
	 g6  
	 g7  
	 g8  
	 g9  
	 g10
	 g11  
	 g12  
	 g13  
	 g14  
	 g15  
	 g16  
	 f Objective function;

f  .. objval =e=0.00432*F1+0.00432*F13+0.01517*F2+0.01517*F9+0.9979;
g1  .. F1+F2+F3+F4 =e= 300;
g2  .. F5-F6-F7 =e= 0;
g3  .. F8-F9-F10-F11 =e= 0;
g4  .. F12-F13-F14-F15 =e= 0;
g5  .. F16-F17-F18 =e= 0;
g6  .. -F5+0.333*F1+F13*xA12 =e= 0;
g7  .. 0.333*F1+F13*xB12-F8*xB8 =e= 0;
g8  .. 0.333*F1-F8*xC8 =e= 0;
g9  .. -0.333*F2-F12*xA12 =e= 0;
g10  .. 0.333*F2+F9*xB8-F12*xB12 =e= 0;
g11  .. -F16+0.333*F2+F9*xC8 =e= 0;
g12  .. 0.333*F3+F6+F14*xA12 =e= 30;
g13  .. 0.333*F3+F10*xB8+F14*xB12 =e= 50;
g14  .. 0.333*F3+F17+F10*xC8 =e= 30;
g15  .. xB8+xC8 =e= 1;
g16  .. xA12+xB12 =e= 1;

* Bounds
F1.LO = 0; F1.UP = 300;
F2.LO = 0; F2.UP = 300;
F3.LO = 0; F3.UP = 300;
F4.LO = 0; F4.UP = 300;
F5.LO = 0; F5.UP = 300;
F6.LO = 0; F6.UP = 300;
F7.LO = 0; F7.UP = 300;
F8.LO = 0; F8.UP = 300;
F9.LO = 0; F9.UP = 300;
F10.LO = 0; F10.UP = 300;
F11.LO = 0; F11.UP = 300;
F12.LO = 0; F12.UP = 300;
F13.LO = 0; F13.UP = 300;
F14.LO = 0; F14.UP = 300;
F15.LO = 0; F15.UP = 300;
F16.LO = 0; F16.UP = 300;
F17.LO = 0; F17.UP = 300;
F18.LO = 0; F18.UP = 300;
xB8.LO = 0; xB8.UP = 1;
xC8.LO = 0; xC8.UP = 1;
xA12.LO = 0; xA12.UP = 1;
xB12.LO = 0; xB12.UP = 1;

* Starting point (global solution)
* F1.L = 60.0601; 
* F2.L = 0;
* F3.L = 90.0901;
* F4.L = 149.8498;
* F5.L = 20;
* F6.L = 0;
* F7.L = 20;
* F8.L = 40;
* F9.L = 40;
* F10.L = 0;
* F11.L = 0;
* F12.L = 20;
* F13.L = 0;
* F14.L = 20;
* F15.L = 0;
* F16.L = 20;
* F17.L = 0;
* F18.L = 20;
* xB8.L = 0.5; xC8.L = 0.5;
* xA12.L = 0; xB12.L = 0;

MODEL test /ALL/;
SOLVE test USING NLP MINIMIZING objval;