3 replies to this topic

Dear all,

I'd like to know the key parameters or general principle for selecting the pall ring to the column. The pall ring parameters from vendor are about BULK DENSITY, ESTIMATED WEIGHT, SURFACE AREA, VOIDAGE and PACKING FACTOR. Which one is the most critical one? Firstly, the way i tried to select is calculate the pressure drop of packing then compared with the pressure drop/bed of the design column.

dp of pall ring = weight of pall ring * g (9.81 m/s2)/ Cross sectional area of column x (1-voidage of pall ring). (based on dp = force / Area)

Not sure whether i'm right. Anyone pls share your comments.

Thanks in advance ,

[Zauberberg]

In general, for identical vapor/liquid loads, efficiency (and pressure drop) increases as the packing size is reduced. In other words, using smaller size packing would result in less packing height required to achieve the same number of theoretical plates, but at the expense of higher DP.

Increasing the size of packing reduces pressure drop, and increases HETP. It also calls for more careful design of liquid distribution devices as it becomes more difficult to avoid channeling. In any case, you should leave the selection process to the packing vendor - just make sure to properly define process requirements (flows, operating conditions, product specs) and constraints (DP or tower height) from your side.

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Thank you for ur comment Zauberberg .

Actually, i need to change the pall ring during this major turnaround and it is the 1st time to change pall ring. It is not for the new column. But the information in my site has stated just only pall ring 1" MPR .

Then a few vendors sent me the technical data of pall ring such as bulk density and voidage with different thickness of 1" pall rings as i stated before. Hence, i doubt which parameters should i specifically consider to judge that it suits my bed? Or which pall ring from different vendors is the best?

Data at my hand is the design simulation results of absorber namely liquid loadings, gas loadings, packing factor, pressure drop per bed. Hence i simply calculate pressure drop from the design data of pall ring compared with my design pressure drop/bed.

Maybe i need to send the material balance to let vendor confirm again >_<

Thanks once ^,^

[fra.telli]

Maybe i need to send the material balance to let vendor confirm again >_<

Thanks once ^,^

Exactly!
Send them operating conditions, bed(s) desciption and ask for two alternatives:
lower deltaP @ same outlet conditions (or equivalent advantage)
same bulk volume @ best price (& possibly better outlet conditions).

Let them work for you (but give them parameters for it).

bye