placement of blowdown tank 1

[vinman]

In most plants I have worked in the boiler blowdown flash tank is usually on a lower level of the plant. Is it acceptable to mount the blowdown tank approximately 13-30 feet above the boiler?
Thanks!

 

[jproj]

I'm not the definitive source for information on this subject, but I can think of several reasons I wouldn't want to do this:

1) Blowdown is used to get rid of the sediment in the boiler if I'm not mistaken. This sediment will leave the boiler much easier if it is flowing downhill. Also, with an intermittent blowoff (uphill), some sediment may not make it to the blowdown tank and will either trickle back down the line with the rest of the liquid when the valve is closed or settle somewhere in the middle of the pipe (either way, not good).

2) As I mentioned above for an intermittent blowdown, your pipe from the boiler to the blowdown tank will not empty on its own. The fluid in the pipe will drain back to the blowoff valve. I can't tell you if this is good or bad, but I would think you wouldn't want this situation.

Sorry I can't answer your question. I'm sure your proposed design could work if the proper measures were taken to avoid problems (I'm sure it's been done before). Hopefully someone else can give you some better information!

Best of luck!

Jproj

 

[quark]

Vinman!

Jproj is correct. The blowdown should be in such a way that it should create smooth flow to the impurities settled in the bottom of the boiler drum.

For Jproj's second point I can say it's bad for, water accumulated in the pipeline will cause damage when it's being blewn out during blow down. I heard of one such fatal accident, but incase of safety valve where there was no drain point provided below the safety valve discharge line elbow.

However I feel you asked this question for some purpose.
I am very much interested to hear it.

Regards,
Truth: Even the hardest of the problems will have atleast one simple solution. Mine may not be one.

 

[MJCronin]

Vinman,

Quark and jproj are right..... the concerns they expressed are valid.

"Blowdown tanks" (which is what you are refering to) are mostly used to remove built-up solids nad to drain the boier during an outage.

Having blowdown lines that "go uphill" will leave the solids to settle and block these lines. You still have to have some means of draining the boiler......... You might as well locate the blowdown tank as low as possible in the facility.

Consider smaller multiple tanks as an alternative. All blowdown and blowoff piping should slope to the tank and the tanks should be located over a process sewer.

See

http://www.pennseparator.com

for more info

Good Luck.....


MJC