Calculate Time and Temperature for Depressurization of High Temp Water

[rcdooley]

Hello All,

I am trying to calculate the time vs temperature for depressurizing a high temp water application. The water is pressurized to stay in the saturated state at 200C and I want to be able to have physical calculations other than a demonstration that the vapor is safe upon a leak (or opening a small valve). I have been looking over some of my old thermal books and am having trouble coming up with the correct method to approach what I want to calculate.

Internal Pressure: 16 bar (232 psi)
External Pressure: Open atmosphere
Internal Temperature: 200 Celsius
External Temperature: Ambient Temperature (~25 Celsius)
Medium: Water

Thank you for any help you can provide me.

 

[BigInch]

I think you'd better demonstrate that using a dead chicken first.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[rcdooley]

Our YouTube Channel with a video of a technician demonstrating that pressurized water systems are safe.

http://www.youtube.com/user/SINGLEtemperatureUSA

Better than a dead chicken, a real chicken. Our equipment is safe, I know thermally the dispersion and expansion with the pressure change and the system being under the saturation line the water depressurizes as a mist (water vapor not steam). I do not like to assume and have proof, I want to be able to calculate the change as the water escapes from our system.

 

[BigInch]

Your video demonstrates a closed system including nothing demonstrating safety upon leakage. Now I smell fish.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[rcdooley]

There are two videos on the YouTube Channel!

The video that you are talking about is our ATT system.

The other video demonstrating a technician opening a valve (to simulate a rare but possible fault in a hose) and placing his hand about a foot from the stream out of a unit at 392 F.

Nothing fishy, we have been manufacturing temperature control units for more than 40 years. Our high temperature units have been in use for more than 30 years. We are the leading technology in our field. Please do not mistake this post for nothing more than me asking for support from everyone's knowledge to solve something that I am curious to have numbers to prove. Nothing fishy, ask your self something basic- what happens to a spray can when you release the pressure? Same principle but different scenario.

 

[rcdooley]

http://www.youtube.com/user/SINGLEtemperatureUSA#p/a/u/0/S6yHmLg5LP8

 

[IRstuff]

Don't you have temperature sensors in the system already?

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[rcdooley]

Yes, we normally have three temperature sensors internally and can have an external temperature sensor. There are many safety and protection systems in the unit. This is not about safety, it is about being able to calculate the temperature vs time or distance from the unit.

 

[BigInch]

the vapor is safe upon a leak

Your mistake. We thought you said safe in there somewhere.


Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[chicopee]

"...the vapor is safe upon a leak..." tell that to power plant operators and note their responses.
Now, I have been told by former navy personel and I have no reason to doubt them that they would use brooms to detect steam leaks and not their hands. Leaking steam would cut those brooms.

 

[willhammett]

I agree with chicopee, we use wicker brooms. They prove to be a lot cheaper than thermal imaging cameras.

 

[BigInch]

Put your hand in 50 # of that stuff and you pull back only bones, if you pull back anything at all.

Any blanket statement of safety appears rediculous. Each leak would have to be evaluated with its own particular rate, size, disbursment patterns. Trying to evaluate this using a necessarily idealized model would also present a problem. Leaks don't often happen through the geometry of an ideal orifice, for example. You accomplish nothing even if you could prove that was safe at distance X. If you proved a minimal leak was safe at a distance of 200 mm, what does it say for a hand only 100 mm away, or for a leak that is slightly larger than "minimal". The answer isn't binary, except for the chicken.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[rcdooley]

This is not a STEAM SYSTEM. It is a High Pressure Water System. This means that high temperature water is circulating and NOT STEAM.

Think of it this way. Pressurized R-22 is in a liquid state, but after passing through the expansion valve changes into its gasious state by an isenthalpic process (I believe that is the correct term) and the gas through drop in pressure goes to a lower temperature. The expansion can be calculated by P, V, T. My problem calculating is that the gas ends up in an undefined volume and can not think of how to calculate this. Please help and do not come off demeaning. This forum should be for support.

I will assume an 1/8 line, just like the video, for the leak.

Why do you think people switch to these units instead of getting boilers?

 

[vpl]

Good salesmen ....

Patricia Lougheed

******

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[BigInch]

Whatever the reason, one thing for sure is they're not switching because they're safer.

I would so much more rather use electric heating. Safe, easy, no messy leaks, no relief valves, no water boilers, no valves, no exploding pipes.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus