Distillation Cards

The two operating lines intersect at xq, yq

• ESOL LINE: Yq Vn = Xq Ln + D Xd
• SSOL LINE: Yq Vm = Xq Lm - B Xb
• ESOL - SSOL
• Remember F Zf = D Xd + B Xb

        So Vf  Yq = -Lf Xq + Ff Zq

 q gradient = -(Lf)/(Vf)

q line limits are from 0 to -infinity

0 represents the dew point

-infinity represents the boiling point

q = (Enthalpy required to vaporise 1 mole feed) / (Enthalpy required to vaporise 1 mole of liquid at its boiling point)

OR

q = (Enthalpy required to vaporise 1 mole feed) / (Molar Enthalpy of Vaporisation)

= (hv - hf) / (hv - hl) or    (hv - hf) / (hlv)

α = (Saturated vapour pressure of A) / (Saturated Vapour pressure of B)

Pa=Xa Poa

Pa=Ya PT

First do a mass balance multiplying compositions and flowrate. Feed equals vapour plus liquid of the more volatile component. Then try to find an equation V/F

It is when the vapour composition from one plate to the next is divided by the equilibrium change.

You can redraw the VLE line closer to the operating line. Allow for ηm.

They are asking you to calaculate Db which is S1-S2

which is equal (Xd - Xs1) / (Xd - Xs2)  

It is used when  CONSTANT MOLAR OVERFLOW can not be assumed

1.Latent of Vaporisation change from stage to stage

2.Significant heat of mixing

On the x=y, draw Xb

Then start from there and draw the number of stages

Stop when 0.95 is exceeded on the x=y line

These are the number of theoretical stages