HRSG Preservation with N2

Aren't they supposed to be full of steam?

Nitrogen for HRSG Layup - South-Tek Systems Blog

HRSG Training | HRSG Users Group Combined Cycle Power Plant ...

This sort of stuff ought to be in the User Manual supplied with it. If it isn't, or the manual is missing, then it's time to contact the boiler manufacturer directly; pick up the phone and get dialling.

It does need to be dry first, ideally a dewpoint of -20 Deg C.

You'll find it hard to get nitrogen with less than 99% purity out of a bottle or from vapourised liquid. if your running a generator (membrane or PSA) 98% purity will be fine. Oxygen content of less than 2% by volume should be your target IMHO.

Want to know how much you will need, tell me the volume and the pressure rating and I'll show you the cycle purge calcs, much more effecient than just displacing for anything that isnt just simple pipe.

Dear "HeHound", many thanks for your comments. Total volume required to fill the HRSG is about 157 cubic meters at 5 psig (0.35 barg). I will be grateful if you can show me the calculation for how many cylinders will be used and also what extra margin of volume has to be provided to account for leakages assuming leakage rate of 1 cu meter per hour.

Regards

Your less expensive application will most likely be a liquid N2 dewar with 150 liter of LN2 (I think this is the standard size, as I recall), and a small heat exchanger to cover the heat input of vaporization. Direct sunlight on this or just hot desert air should be sufficient. Depending on local humidity, you might do just as well by simply blowing hot dry air through the HRSG once drained, and once the metal is dry, you will have slowed corrosion to the flow of ashpalt in Antarctica.