Nitrogen Cooling of High Temperature Piping

[4fletch]

Does anyone have experience with forced cooling of high energy steam piping with nitrogen? My goal is to reduce schedule time and improve safety for asbestos abatement workers removing insulation from hot reheat piping by reducing pipe temps to ambient upon shutdown asap. The pipe will be demo'd and replaced with new. The other goal is to do so without detrimentally affecting the HRH outlet header or turbine connections. Is this a bad idea or worth pursuing??

 

[SJones]

I can only think of safety issues regarding asphyxiation of the workers.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[IRstuff]

You really need some decent conduction possibly coupled with a phase change to really get decent thermal cooling.

Nitrogen gas is neither and is a potential danger.

TTFN

 

[4fletch]

Let me clarify a bit, I was thinking in terms of injecting N2 or LN into HRH piping at existing test connections and venting in direction of roof exhausters.

 

[StoneCold]

4fletch
Don't put liquid nitrogen into the pipe. One, I am pretty sure your piping is carbon steel and not made for liquid nitrogen temperatures. The second is, that it is pretty easy to get a lot of moles of nitrogen into a closed system very fast, combining that with the brittle nature of cold carbon steel and you have the makings of a three finger Joe film.

What about just using compressed air or low pressure steam? I think if you do the math that the volume will be very large for air but you might get better results for superheating steam and as the pipe cools off feed compressed air.

 

[IRstuff]

The cooling capacity of either is really quite poor. Given that air is 78% nitrogen, you're better and cheaper off simply blowing tons of chilled air at the piping.

However, given the lack of suitable heat fins, the overall cooling efficiency will still be quite poor.

Unless your system was designed with this intent in mind, you're most likely going to waste a lot of money and resources for very little benefit.

TTFN

 

[4fletch]

OK, thanx to all for the input. Was kind of enthused about the notion, but figured if it was a poor one, would not withstand scrutiny.