What is a knockout tank? does it condense the gas to become a liquid, or does the gas just past through and get the saturated liquid knocked out of it?
A knockout tank is designed to perform a crude disengangment of gas and liquid. The area of the flow is increased and the velocity of the gas drops.. therefore the dropless of entrained liquid (ideally) are no longer carried forward beyond this stage.. or most of them anyhow.
It is also a way to "kill two birds with one stone" in a sense. It removes most of the entrained lquid, but also allows solids to settle out.
Be mindfull about temperture and pressure entering the knockout drum however, because if hot or pressurized fluids enter a knockout drum, the lost energy through the phase change has nowhere to go in a closd system and you will damage equipment, if not personnel as well.
Your warning does not apply to entrained liquid knock-drums in gas service.
In the case of high-pressure liquids flowing into a lower pressure "flash drums", there is a partial vaporization of the liquid which causes the liquid temperature to drop. That is is known as "auto-refrigeration" (used in many refrigeration systems). I don't understand what you mean by "lost" energy potentially damaging the flash drum.
Milton Beychok
(Visit me at www.air-dispersion.com)
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The usual definition is a vessel, drum or trap used to remove fluid droplets from flowing gases, with or without demisters. It is usually vertical, but it can be horizontal when the amount of liquid to be removed justifies it economically.
May be a visit to the following threads may add perceptibility:
I am aware that my warning does not apply to entrained liquid kock-out drums in gas service. However, the OP questions was What is a knockout drum. The exaple he used did use gas service, yes, but thats not a knockout drums sole purpose.
Yes, my example was of liquid flashing off, however, liquids can flash off in knockout drums. Even highly saturated vapors can, so my advice was not completely uncalled for.
As for when I used the term released energy from the phase change, I'm refering to the energy let off in the form of pressure as the volume of the liquid->gas increases roughly 1000 fold.
