7 replies to this topic

[BigRedEnvEng]

I'm working on designing a nitrogen blanketing system for a 500,000 gallon demin water tank. The plant uses a large amount of demin water about 12 times a year for startup operations, but the rest of the time it's at steady state operations with a low flow. From my rough calculations, I'm thinking we're probably going to need about 74 scfm of nitrogen during the large pushes, and small amounts to maintain stead state for the rest of the time. Does anybody have any suggestions as to the pressurization required on the tank? I also wanted to hear ideas of nitrogen generators versus cylinders versus cryogenic storage tanks if people have had experiences with either/both and if anyone has suggested manufacturers (if that's allowed). Any thoughts would be appreciated.

[proinwv]

Hi, you have lots of good questions.

Well the blanketing pressure depends first on the allowable wp of your tank. Remember that you need to have additional venting to protect the tank.

Many blanket at pressures of about 1 in. wc. which in itself is ok, but I prefer a bit higher to assure that the does not drop into the negative range and cause the vacuum vent to open. This can happen due to a high load on the prv, and the resultant droop causing a lower than expected controlled pressure or temperature changes. Elevateed control points help stay away from the problem. Again, only if your tank is capable. You might look at some of the information on my web page, www.ostand.com.

I have often heard of dissatisfaction with using bottled N2 due to cost and limited volumeteric capacity. I suggest discussing options with suppliers of N2 as well as manufacturers of generators. It doesnt sound like your demand is too great.

PAUL

[Art Montemayor]

Big Red:

If you go to the following Forum Thread you will find a .zip file that contains Excel Workbooks on this subject and perhaps they may help and answer your questions. Look on the last post on page 3 of 3.

http://www.cheresour...t=50

[pleckner]

Art:

It's not working, something is wrong with the zip file?

[proinwv]

Art,

I agree, the file is corrupted.

[Art Montemayor]

Phil & Paul:

You were right; the attachment was not down-loadable. I have now fixed it and it should work for everyone who tries it.

I deeply apologize for being a corrupted individual. I'll work on improving my future postings and attachments.

Thanks guys,

Art M.

[pleckner]

Art,

We love ya!

[BigRedEnvEng]

Art - Thank you very much, the zip file is incredible. Thank you very much for sharing with us, I appreciate it!

Paul - Thank you for your input, I see what you're saying about the pressure on the tank and I will definitely take that into consideration.