3 replies to this topic

[Steve90]

Hi ;

 

While installing a Butanizer After the ethanizer in HYSYS  i didn't find the adequate spec to release most of butane without loosing propane in overhead product.

 

I tried propane fraction of 0.05 in condenser and 5e-3 butane in reboiler but the column don't want to converge.

 

The feed stream is composed of :

 

i-Butane         0,1357
n-Butane         0,2534
i-Pentane         0,122
n-Pentane         0,1094
n-hexane       8,073e-002
Propane          0,297

 

feed stream conditions :

 

Vapour / Phase Fraction              0,61989
Temperature [C]                             67,02
Pressure [bar_g]                          5,93675
Molar Flow [kgmole/h]                 18,70955

 

Column conditions :

 

operating Pressure                   689 kPa

Number of trays                             25

 

 

Thanks

 

 

 

[Zauberberg]

The pressure seems to low. Depropanizers operate at around and above 10 barg.

[Steve90]

No i'm dealing with a debutanizer because i think that in LPG Unit we are used to install the debutanizer before the depropanizer for economic reasons.

[Zauberberg]

There is no way you can achieve 5% C3 in the condenser with basically entire C4 recovered in the same stream. If Butane goes overhead, entire Propane will go overhead as well. It is lighter component than Butane.

 

If you set up e.g. 2% n-C4 in the reboiler and 1% i-C5 in the condenser, you should get a decent separation between LPG and C5+ components.