Hi

For a combined cycle power plant, we are designing the steam headers. To avoid condensate accumulation during start up (and other conditions) we are adding drip legs along the headers. Those drip legs are draining into an Atmospheric Condensate Receiver, that is pumped to other location when is required.

Our concern is about the end of the warm up; because we think steam could flow through the drip leg, and go into the Atmospheric Condensate Receiver.

We have a vent in that receiver, but we want to be sure it is enough size to avoid pressurization.

How could we estimate the maximum flow of vapor going through the drip leg (and the system)?
 

There will typically be traps on the drip legs. These are simply automatic valves that open when the sense air or water, and close when they sense steam.

There are a number of manufacturers, all of whom provide loads of very informative literature for selection & sizing - Spirax Sarco, Armstrong, Hoffman, etc.

Must use steam traps (as mensioned)  and must have safety rilief valve at the tank or a large vent that will allow all the vapors to release from the tank with only small overpressure.