3 replies to this topic

[Chemster980]

Hi,

I am doing a shortcut design on an packed bed deaerator. Background of the problem: removal of oxygen in feed water as part of the process to prepare makeup water for boiler. Feed properties:
T = 50C
O2 = approximately 5.5mg/L
Target= a minimum of 0.005 cc/L of oxygen.
Flowrate of water: 5.4 m3/h

Steam entering from the bottom of the bed is 100C at 101.3kPa(a)
Packed bed is also operating at 101.3kPa(a)

The diameter could be determined from flooding point (page 225 Coulson and Richardson volume 2) - feel free to correct me if there is other method that i should consider in determining the diameter.

I could not determine the height. Can someone please enlighten me?

Thanks a bunch

[kaisar]

Dear

I think it's simple thing. You already have the diameter. First you have to do is calcaluting the bed (or adsorbent) need. What do you use?? Multiply it by 25 % as safety factor (rule of thumb). To find height you can divide the volume of adsorbent needed by the inside area of the packed bed column. You see??
I hope it's helping.

[Chemster980]

Thanks for such a quick reply. I got what you mean, but I couldnt get any literature or information to setup the amount of packings (volume). [already spent 3 days on this]

If anyone have such literature information please let me know or attached to this topic. Thank you very very much!!

[djack77494]

Chemster,
I do not agree with the suggested approach. That would treat your packed bed as if it were a solid sorbent. That is definitely NOT the case. You have a mass transfer problem and need to provide enough contact and residence time for the unwanted oxygen to be driven from your boiler feed water. It is then carried along with the uncondensed steam and leaves via a small vent line at the top of the deaerator. I don't know the appropriate design equations off the top of my head, but they should be easy to find in any transport phenomena textbook.
HTH,
Doug