5 replies to this topic

[Vegeta]

Dears, 

 

if we have a saturated steam flowing in a long well insulated line, we know that it will experience a pressure drop as well as a temperature drop. my question is: can this drop in pressure and temperature cause a phase change or it is going to be just a lower pressure saturated steam? and why?

 

Sorry if the question is trivial. 

[Zauberberg]

It depends. For longer lines having no insulation you may get significant amounts of condensate, if the surrounding temperature is low enough. For short-distance insulated lines this will normally not happen.

 

There is a handy spreadsheet in the download section - try it: http://www.cheresour...pipe-heat-loss/

[katmar]

A common practice to prevent the formation of condensate is to control the upstream conditions to have 5 to 10 degrees of superheat.  High pressure boilers usually generate superheated steam at temperatures and pressures above what they will be required by the end users, so a let down station and desuperheater would have to be installed anyway.  The desuperheater is set to leave a few degrees of superheat in the steam so that you can get close to dry saturated steam downstream.

[fallah]

Vegeta,

 

Because it's not expected the rate of pressure drop to be harmonized with temperature drop such that the saturation being kept but at lower pressure; then you are normally faced with either a degree of superheat or a little bit condensation...

[curious_cat]

Long steam delivery lines almost always have steam traps installed at periodic intervals. Looking at how often they release I think there's a decent amount of condensation happening in practical lines, no matter how well insulated. 

[breizh]

https://www5.eere.en...amo_steam_tool/
Vegeta,
To support your work .

"Agree" with both  Harvey and Curious cat .

Hope this helps

Breizh

Edited by breizh, 06 April 2015 - 07:39 PM.