4 replies to this topic

[marchese85]

dear all
I have to size a column with structured packing for a batch distillation?? the packing that i used is a sulzer mellapak 500.
how can i do????
can someone post a link refer to this type of sizing????
best regards
p.s. sorry for my english
thenks in advance

[siretb]

Hello,

The procedure is not different from the one you would use for a continuous distillation column.
First you determine the worst conditions for the L liquid rate and V vapor rate. For a batch distillation, since reflux may vary, L and V may, one or both, vary with time.

For a Sulzer packing, the best is to use the F factor. determine on their curves, depending on the wettine rate (m3/m2/hour) the allowable F factor (for metallic 500Y the maximum F is around 2.2 m/s*sqrt(kg/m3), but do not operate above 70-80% of this maximum.
The 2.2 given is just an indication, the actual maximum F factor will depend on the system, and on the irrigation rate.

F is the product of the gas velocity (m/s) times the square root of the specific mass of the vapors (kg/m3)

You know your vapor rate V (kg/second) you know F you calculate the diameter

You must know the required number of stages (or NTUs) 500 Y is about 4 stages/meter (check, this is system dependant),; this gives the packing heigth.

I'd like to point out that structured packing is not always the best choice for a batch distillation. Consider trays also, the choice will be dictated by pressure drop, holdup requirements, operating pressure, ...)

[marchese85]

thanks a lot siretb

I founded online catalog of sulzer about your structured packing . This refer to a F-factor to find the hetp required but I don't find any reference to the flow of liquid.

can you indicate some articles or links that describe the procedure for determining the critical conditions of column working???
i attach the sulzer catalog!!!!!!!!

thanks in advance!!!!!!!
p.s. sorry for my english

Attached Files

•  28435417-Structured-Packings-Sulzer.pdf   2.3MB   212 downloads

[siretb]

For any packing and strucured packing is no exception the capacity curves incorporate both the vapor rate and the liquid rate
the flooding point arises for a gas rate that is lower when a high liquid rate is used (say >125 m3/m2/hr) than when a low liquid rate is used (say 10 m3/m2/hr)

This will be specific for each packing and you will have to find better curves, from the supplier. In practice, unless you operate at a high pressure, the curves that you have will suffice to select the operating point, as long as you stick to my advice: do not design beyond 80% of flooding.
However, if you want a good estimate of the pressure drop, you'll need more detailed curves.

[sjingade]

Hai,

Thanks for giving information about sulzar packing, i found lot information F factor and formulae required to designing of the packed column.

Thanks a lot, can u please send your email id to discuss lot on distillation design by thereotical.

If any body want share the knowledge regarding distillation design therotically along with practically.

My mail id sunil.prodn@gmail.com

J M Sunil

thanks a lot siretb

I founded online catalog of sulzer about your structured packing . This refer to a F-factor to find the hetp required but I don't find any reference to the flow of liquid.

can you indicate some articles or links that describe the procedure for determining the critical conditions of column working???
i attach the sulzer catalog!!!!!!!!

thanks in advance!!!!!!!
p.s. sorry for my english