STEAM SURFACE CONDENSER WITH 254 SMO TUBES

[dtorresa]

Hello Everybody,

This is my first time at this Forum.

I would need help in designing water cooled steam surface condenser with Stainless Steel 254 SMO (UNS S31254)tubes, since this material is not considered in HEI for Steam Surface Condensers.

HEI overall heat transfer coefficient calculation is based on 18 BWG Admiralty tubes and 70ºF water inlet temperature, with some correction factors based on tubes material and thickness, inlet water temperature and cleanliness factor. In this way, and considering that the material correction factor is not tabulated in HEI for 254 SMO tubes, how can I estimate this correction factor and in consequence the overall heat transfer coefficient?

Thanks!

 

[speco]

dtorresa,

Here's one way to do it. Determine the thermal resistance of the 18 ga Admiralty tube, based on its thickness and thermal conductivity. Take that resistance out of the overall heat transfer resistance (1/overall coefficient) from HEI. Then calculate the resistance of the 254 SMO tube using its thermal conductivity and thickness. Add that resistance back into the overall resistance (less the Admiralty resistance). Then invert the new R total, and you get a reduced overall heat transfer coefficient.

Regards,

Speco (

http://www.stoneprocess.com)

 

[MJCronin]

I am a little curious about why this alloy....- 254 SMO, was selected for tubes in steam condenser service....

254SMO is an austenitic stainless steel and is the first cousin to AL6XN

( I am more used to either SEA_CURE or Titanium being the prudent choice)

What is the range of chlorides for the water on the tubeside ?

Also, what material was selected for the tubesheet face ? Can you explain how are you attaching the 254SMO tube to the tubesheet ?

Why are you selecting such a high thickness for this service ? ( you selected 18 BWG vs. 22 or 25 which is more commonly selected ?

Here is an informative paper.....

http://www.plymouth.com/media/13960/Sel Tubing Mat for Pwr Gen _SW Chem_.pdf

The Swedes at Avesta also recommend the "big brother" to 254 SMO for chlorinated seawater service...... 654 SMO

http://www.outokumpu.com/SiteCollec...stainless steel for condenser tubes_35967.pdf

Tell us more about your design conditions....