I have a counter current spray packed scrubber for acidic gases like HBr and some high molecular weight hydrocarbons along with hydrogen coming off a hydrogenator. The scrubber leaves a fine mist that no mist eliminator seems to catch. I am imagining these fine droplets are produced during hydrogenation. On another similar application, we have a a bubbler that is doing fine as a scrubber and this one does not leave any mist behind. The problem is, bubbler is all Hastelloy C and very expensive compared to a fibreglass packed scrubber. Could anyone point me to a less expensive solution. thanks
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scrubber design info
- Thread starter slj
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Yes, thanks for suggestion; that is what I was wanting to do but could not.
The newer application is almost twice the capacity and even if I kept the same liquid depth and same velocity thru each tube, there perhaps might be some mass transfer considerations in selecting the number and diameter of tubes And since it is the mist eliminating (rather than scrubbing) that I was interested in, should I consider this more like a impingement separator?
I was wondering if any design references are available?
One fiberglass manufacturer I approached (in Canada, he could not make that bubbler.
thanks
The newer application is almost twice the capacity and even if I kept the same liquid depth and same velocity thru each tube, there perhaps might be some mass transfer considerations in selecting the number and diameter of tubes And since it is the mist eliminating (rather than scrubbing) that I was interested in, should I consider this more like a impingement separator?
I was wondering if any design references are available?
One fiberglass manufacturer I approached (in Canada, he could not make that bubbler.
thanks
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- #4
I'll clarify the situation further. The net mass transfer in the bubbler will be a function of surface area and residence time of bubbles (besides pH and the inlet gas concentrations which should stay unchanged) and this should be equivalent to the NTU's of the packed scrubber. If there was a way to answer this, then there will be a lot more confidence in the bubbler design.
As far as the mist elimination design, have no clue how to proceed; just know the current smaller one works.
As far as the mist elimination design, have no clue how to proceed; just know the current smaller one works.
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801217
Petroleum
- Mar 10, 2008
- 9
There are two checking point for your problem, one is the mist eliminator, the other is the packing.
1/Please provide the detailed information of the mist eliminator, such as surfacr area, density and void ratio, vapour and liquid flow rate and property.
2/please provide vapour and liquid flow rate and property for the packing for hydraulic checking
1/Please provide the detailed information of the mist eliminator, such as surfacr area, density and void ratio, vapour and liquid flow rate and property.
2/please provide vapour and liquid flow rate and property for the packing for hydraulic checking
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- #8
Many thanks for your interest. Here are some of the details you were looking for.
Vapor Flow rate: 18 lbs/h of hydrogen with ~ 5,000 ppm of high boiler contaminants @ ~ 2 psig and 50C
Liquid Flow rate: 28 gpm of ~ 10.5 pH water
Mist eliminator: Koch Otto York Style BD PRF II, 12" dia, 18" long.
Column Internals: #1/2 PVDF Tri-packs, 8' height column, 1' dia.
Attached literature of mist eliminator and packing.
Vapor Flow rate: 18 lbs/h of hydrogen with ~ 5,000 ppm of high boiler contaminants @ ~ 2 psig and 50C
Liquid Flow rate: 28 gpm of ~ 10.5 pH water
Mist eliminator: Koch Otto York Style BD PRF II, 12" dia, 18" long.
Column Internals: #1/2 PVDF Tri-packs, 8' height column, 1' dia.
Attached literature of mist eliminator and packing.
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801217
Petroleum
- Mar 10, 2008
- 9
I have not get any data for 1/2" tri-packing,such as surface area or void fraction. However, I have checked with conventional 1/2" pall ring for hydraulic calculation. It seems that the entrainment is not caused by the packing since the flooding factor is very low. But I don't know the flooding factor of tri-packing. If possible, please tell me more character for the packing or you can check with the packing supplier.
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My mistake, I uploaded the wrong literature. Here is the first half of the literature. Second half I'll upload in the next post.
In my opinion, micron sized fine liquid droplets of high boilers are produced in the reaction upstream of the scrubber. These are so fine droplets that they are not caught by the scrubber and not even the mist eliminator. In scrubber A, where the incoming gases from reaction are bubbled in liquid, the bubbling action is acting like a impingement baffle and condensing / coalescing the fines and that is why no mist is seen coming off that scrubber.
In my opinion, micron sized fine liquid droplets of high boilers are produced in the reaction upstream of the scrubber. These are so fine droplets that they are not caught by the scrubber and not even the mist eliminator. In scrubber A, where the incoming gases from reaction are bubbled in liquid, the bubbling action is acting like a impingement baffle and condensing / coalescing the fines and that is why no mist is seen coming off that scrubber.
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