2 replies to this topic

[Maddy]

Hi All

I am a student and I am new at this topic.

For my thesis I need to develop an algorithm for the design and off-design condition of a condenser in a steam plant.

I am getting confused with a very basic issue. Could somebody say me what happens at the pinch point temperature difference in off-design? At design point we choose it (considering several issues), but for the off design? Can this difference decrease?

Many many many thanks

Maddy

If you choice delta T_min, the pinch point is fixed.

You can calculate heat duty as avaliable, required, net, accumulated.

If you finish your calc, find least accumulated. That is the pinch point.

Another method, you can make composite curves.

then you can choice the pinch point.
the hot stream cruve is fixed. then you can shift the cold stream curve.(left or right)

from the composite curves, you can decide amounts of heating and cooling utilities.

if you choice biggest temp diff, you can get small heat-exchanger but you have to pay more money to use heating and cooling utilities.

otherwise, if you choice least temp diff, you get big heat-exchanger but you can save utiilies's cost.

it depends on you.

p.s I'm not a american. I'm a korean. so my english is so terrible. Plz, understand.

[breizh]

Hello Maddy ,
Hope this reference will help you:
http://www.gulleyass.../news.htm#Nov98

regards
Breizh