Condensate Receiver Sizing
Condensate Receiver Sizing
(OP)
What is the basis for sizing a vented atmospheric condnesate receiver to prevent condensate entrainment/carryover into the vent stack? In my situation, I have a condensate load of 35,000 lb/hr (5,891 lb/hr flash, 29,108 condensate) that is collected in a vented condensate tank and sent either to a hotwell or pumped to a condensate storage tank, depending on the hotwell level and the condensate reciever level. The pump is sized to deliver 100 gpm, well in excess of the incoming condensate. The condensate reciever appears to be undersized (horizontal tank 3' dia x 6'long)and we are draining a "considerable" amount of water from the steam separator that we have installed on the 10" ventline. Any guidance for checking the sizing?





RE: Condensate Receiver Sizing
Basically, you are trying to get the droplets to settle out before the rising steam enters the stack and accelerates to the point that you aren't going to remove any droplets before hitting the stack separator.
RE: Condensate Receiver Sizing
RE: Condensate Receiver Sizing
gladkenn
RE: Condensate Receiver Sizing
I realize that this may be too late for answering your question, but perhaps the following may be useful to others:
The size of a flash drum (or knock-out pot, or vapor-liquid separator) should be dictated by the anticipated flow rate of vapor and liquid from the drum. The following sizing methodology is based on the assumption that those flow rates are known.
Use a vertical pressure vessel with a length-to-diameter ratio of about 3 to 4, and size the vessel to provide about 5 minutes of liquid inventory between the normal liquid level and the bottom of the vessel (with the normal liquid level being at about the vessel's half-full level).
For the maximum vapor velocity (which will set the drum's diameter), use the Souders-Brown equation:
Vmax = (k) [ (dL - dV) / dV ]0.5
where:
Vmax = maximum vapor velocity, ft/sec
dL = liquid density, lb/ft3
dV = vapor density, lb/ft3
k = 0.35 (when the drum includes a de-entraining mesh pad)
The drum should have a vapor outlet at the top, liquid outlet at the bottom, and feed inlet at somewhat above the half-full level. At the vapor outlet, provide a de-entraining mesh section within the drum such that the vapor must pass through that mesh before it can leave the drum. Depending upon how much liquid flow you expect, the liquid outlet line should probably have a level control valve.
As for the mechanical design of the drum (i.e., materials of construction, wall thickness, corrosion allowance, etc.), use the same methodology as for any pressure vessel.
Milton Beychok
(Contact me at www.air-dispersion.com)
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