2 replies to this topic

[djack77494]

I've worked most of my career in the chemical, power, and refining industries and have seen and done many vessel designs that included demister elements. I think that in ALL cases, the demister element(s) consisted of vanes and/or mesh pads positioned horizontally near the top of the vessel. I've recently been working in the Oil & Gas industry and have become aware of the practice of designing new vessels with vertically positioned demister elements. Though I think this is not all that frequent even in the O&G business, I'm nonetheless curious. Do vertical elements offer any advantages? disadvantages? extra design elements that must be added or deleted? How do you size them? I'd appreciate any commentary you might offer on the above mentioned items.

I have a second question, that I kinda know the answer to but would be interested in hearing your responses. Define/differentiate between a Separator/Scrubber/Knockout Drum and a Coalescer.
Thanks,
Doug

[sgkim]

As you understand, demister elements are applied for the removal of liquid droplets from the vapor streams. Since the liquid droplets (collected by inertial, drag, coagulation effects) flow gravitationally downwards, the "vertical" demisters furnish cross-flow aginst the fluid and seem better for high vapor and liquid loads, but more difficult to install. Detailed information are available from the manufacturer.

Separator is a general term of equipment for various separation purposes but usually referred for liquid-liquid "phase" separation equipment, and knockout drum for vapor-liquid separation. Coalescers are mesh pads to "coalesce" small liquid droplets and are internal parts of liquid-liquid sparation equipment. Scrubbers are those to remove dusts or harmful gaseous component by "scrubbing" with liquid sprayed on top of vertical tower.

sgkim/050607

[Technocrat]

Dear all,

Mist eliminator is the generic name and DEMISTER is a trademark of one manufacturer. In horizontally installed mist eliminators the collected liquid is draining against the flow of upcoming vapor hence the liquid drainage rate is hidered. But in vertically mounted mist eliminator the gas flows horizontally and the collected liquid drains at the right angle to the flow of gas. Hence there is less resistance to the drainage of liquid so the capacity for the gas flow is more for the vertically mounted mist eliminator. You may click www.koch-ottoyork.com for more details who are the pioneers and world leaders in mist elimination and coalecsing technology.