Usually in power plant we come across some equipment vents like in case of Gland Steam Condenser or Atm. Drain Vessel etc.
these vents are open to atmosphere for un-condensed steam or air or other non condensable gases .
situations seems ok by now ....BUT the issue arises when i plan to route such vent ...viz.. how we decide by which height we will leave the vent open to atmosphere .......I mean by which height i need to route my vent line?
there is nothing mentioned in P&ID for this .
Any views ,experiences,Ideas,opinions ........please Share ....
This is a very good question and I thank you for asking it.
When we consider "Vents" we must acknowledge that they come from different sources and will have different kinds of discharges. Some dangerous and some just plain annoying. People (Operators and maintenance workers) need to be protected from unpleasant or deadly discharges. Likewise, buildings, equipment, structures and piping should also be free from direct vent pipe discharges that could cause damage.
So, I suggest the following:
1. Is there a Code (where you or your project is) that applies to this?
2. The open end of the vent pipe should be a minimum of 8'-0" (2.4m) above Grade or Platform associated with this vent. The reason for this is Safety. Most discharges from vents can be very hot, toxic or harmful in some manner. If the open end is low enough such that a person could reach it with their hand then, sure enough they will do just that. What will happen to the unthinking person who places a hand over the vent pipe and just then there is a release of super-heated steam? No hand, right? What if it is low enough for the person to look down the pipe? That would be worse.
As a piping designer you should "look" around your design to see what could be affected by the released vapors.
a. People first - Is the open end out of reach?
b. Equipment second - Picture an inverted 45 degree cone sitting on the vent pipe opening and check in 360 degrees in all directions (the wind does not always blow where you want it to) to see where the wind might blow the release.
I am currently dealing with the natural gas vent line on the offshore jetty area, the source points are Pig Launcher & Emergency shutdown valves on the loading arm discharge lines.
While routing these lines following must be considered points are being take care from my side however there are difference of opinions as always in the project team.
1) Vent line should not have any drop & it should be going up-up but never down towards the ultimate safe location of venting.
2) Vent line should not have any pockets even though there are no chances of condensate formation in the natural gas vent.
3) Vent line is critical & stress analysis is required considering NG source line is pressurized & is of 900# for 20â€ NG send out line.
4) Vent line is process critical & process need to review it before final issue of the same.
Need some fine tuning on this with reference to your comments on the same.