Condensate in low pressure superheated steam line
Condensate in low pressure superheated steam line
(OP)
At the power station there is a steam pipe + 100 metres long , 250 mm Diameter , the pipe contains superheated steam at 3.5 barg and 215'C ..... when on load there is no steam demand an no flow (this is auxiliary steam). Historically this pipe has become flooded with condensate due to incorrect size or malfunctioned trap therefore a 50 mm drain valve is left permanently open.
I would like the close this drain valve to a position so that it prevents condensate build up in the line but does not waste excessive steam.....
my thoughts are that as long as drain valve is opened sufficiently so that the steam flow is turbulent then any condensate will get entrained within the flow and thus be removed.
Is my approach correct ? are there better ways of removing the condensate ?
I would like the close this drain valve to a position so that it prevents condensate build up in the line but does not waste excessive steam.....
my thoughts are that as long as drain valve is opened sufficiently so that the steam flow is turbulent then any condensate will get entrained within the flow and thus be removed.
Is my approach correct ? are there better ways of removing the condensate ?





RE: Condensate in low pressure superheated steam line
Another option would be to put a timed solenoid valve on the drain to allow intermittent blowdown.
RE: Condensate in low pressure superheated steam line
RE: Condensate in low pressure superheated steam line
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Condensate in low pressure superheated steam line
This is a +100 meter long 250 mm diameter line that apparently has a single drain valve to remove condensate. Does this have line expansion loops and are they all at the same elevation or do they have any elevation change along the expansion loops or in any sections of the piping?
Thanks,
Ehzin
RE: Condensate in low pressure superheated steam line
RE: Condensate in low pressure superheated steam line
Spirax Sarco has good clear guidelines detailing how steam and condensate systems should be designed.
As I recall, there should be a drain leg everytime that the steam pipe changes elevation.
Large amounts of condensate left in steam piping causes watterhammer and can be dangerous.... Piping systems have failed and people have died.
Is the system properly sloped toward the steam destination location ? Proper slope is also important
MJCronin
Sr. Process Engineer
RE: Condensate in low pressure superheated steam line
RE: Condensate in low pressure superheated steam line
The pipe is on a rack, I guess. You cannot change the traps as you need a shutdown which is not even in the horizon. You also have to cut on steam losses, what do you do?
Think of a scenario where you have pinched the drain valve and saving on a lot of steam. Now, you need to take the steam line back. What could happen? MJCronin has already cautioned you. The pipe might fall off from the rack!
Better procure correct traps, maybe thermodynamic ones and make sure all the traps are replaced in the next shutdown.
In the meantime, cut down on steam losses elsewhere!