Design of a distillation column with a partial condenser.

[farren]

I have to design a distillation column with a partial condenser and there are 2 overhead products. How different would this design problem be compared with the design of a total condenser column, with respect to the tray by tray calcuations etc.

 

[ash9144]

Tray by tray no difference. Partial condenser is simply one more stage.

 

[sshep]

More info about what you are doing would be helpful. It isn't clear if you have one or two distillate products (vapor and liquid or just vapor), how you are doing these calculations (graphically, hand calcs, or computer program), what sort of condenser vfrac (or temp spec) you are designing for, if the system is multicomponent, etc.

The condenser is a flash calculation (general case) with the case of total condenser being trivial for the saturated reflux condition. For the total condenenser case in a graphical analysis (McCabe-Theile) a horizontal line connects the equilibrium curve with the 45 degree line to locate the point where the top operating line is drawn- this is because the top tray vapor composition becomes reflux composition. For a partial condenser, the reflux composition will not be the same as the top vapor composition. The reflux composition is most easily determined by flash of the top vapor according to your flash specifications (most likely temperature, composition of a phase, or vfrac). This reflux composition can then be used in your itterative tray calcs (if you are doing by hand).

Anyway, if you give some more detail then you can probably get a more useful response.

best wishes,
sshep