piping for superheated steam
piping for superheated steam
(OP)
I have 3 interrelated questions about superheated steam piping:
1) Good piping practice for saturated steam is to connect the branches on top of the headers. However, considering that in superheated steam lines there is not condensate, is this also a recommended practice or connections can be done at sides or bottom?
2) Is is necessary to install steam traps in superheated steam lines?
3) Can vertical loops be installed in a main superheated steam line?
I understand that condensate can be formed in a superheated steam line during startup, but it will be re-vaporized once superheated vapor starts flowing, so it may be that this will take care of the condensate problem in the above 3 cases.
I'll appreciate your opinion.
1) Good piping practice for saturated steam is to connect the branches on top of the headers. However, considering that in superheated steam lines there is not condensate, is this also a recommended practice or connections can be done at sides or bottom?
2) Is is necessary to install steam traps in superheated steam lines?
3) Can vertical loops be installed in a main superheated steam line?
I understand that condensate can be formed in a superheated steam line during startup, but it will be re-vaporized once superheated vapor starts flowing, so it may be that this will take care of the condensate problem in the above 3 cases.
I'll appreciate your opinion.





RE: piping for superheated steam
But I don't know how you will ever get it started up.
While you are right about the condensate re-evaporating, it can and most likely will be be entrained by the flow and transported downstream before it evaporates and do significant damage.
Design your piping correctly and you won't have to worry about it.
rmw
RE: piping for superheated steam
RE: piping for superheated steam
If your shuts are infrequent then it may not be safe to rely on a steam trap that has been sitting closed for many months. Can you be sure it will work again? It might be better to use manual drain valves for start up.
I would not rely on the superheat in the steam to re-evaporate any collected condensate and the line should be drained at start up either automatically with traps or manually via hand valves on the drip legs. During start up the line should be treated like a saturated steam line with all the normal precautions against water hammer and so on. In other words - start slowly.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: piping for superheated steam
In general, follow steam best practices and take off from the top of the pipe. Install drip pockets at suitable locations - changes in direction, particularly vertical up & down (takeoffs), end of mains, and periodically in long horizontal runs.
The steam traps should be sized for the running load, not the warm-up load. As stated in another reply, the start-up should be supervised and the cold condensate drained manually via the mud leg vales.
The steam traps can either be thermodynamic or bimetallic thermostatic, both of which will work on SH mains.
RE: piping for superheated steam
Safe to say that some precautions should be taken for above reason, in addition to:
(i) dewatering after hydrotest;
(ii) dewatering after shutdown and getting ready for startup.
I would go for designing like saturated steam. The use of SH steam is for satisfying process conditions, not for pipeline designers to save money in traps or drains.
RE: piping for superheated steam
I'd dare to add, even if it is not a normal condition, what if one should handle an emergency situation which asks for operation on saturated steam? Keeping in mind this scenario I'd consider steam trapping and I'd also foresee manifolds with the same configuration as that for saturated steam
RE: piping for superheated steam
RE: piping for superheated steam
Regards,
athomas236
RE: piping for superheated steam
RE: piping for superheated steam
They will divide a horizontal segment into multiple areas for drainage.
IMHO, they are also more difficult to support and less "aestetic: than nested horizontal loops.
My opinions only....
-MJC