Clayton Armstrong 2011-02-22 GSK Aranda SP - steam&condensat

STEAM AND CONDENSATE AUDIT

Project N°30275

Date: 04/02/2011

GSK MANUFACTURING Aranda, Spain

Page 41 of 45

Established by E. Morin

To the attention of Ms. Beatriz Herrero-Gonzalo

the steam pressure after the steam control valve is less than the pressure in the condensate line,

there will be no driving force (pressure differential) available to push the condensate out of the heat

exchanger and move it to the condensate receiver. The condensate will back up in the heat

exchanger, and will become flooded. This situation is often called a “stall situation”. As the

condensate backs up in the heat exchanger, it will exchange sensible heat with the product, where

the condensate becomes sub-cooled (matching the product temperature). The infrared pictures

below show the condensate backing up in a heat exchanger and the resulting temperature

differences in it.

The more a heat exchanger is oversized , the sooner it will operate at a partial load and the more

the condensate will sub-cool.

In the best case scenario the control system will balance the steam/product differential. However, in

most cases the following is observed:

Due to the condensate backing up the amount of heated surface in the heat exchanger is reduced,

and the desired set point product temperature cannot be reached. As a reaction to this, the steam

control valve will open, thus providing enough pressure differential to push out the condensate.

When this happens all the heating surface in the heat exchanger is available again causing a

sudden rise in the product temperature. There will be an overshoot in temperature which the