3 replies to this topic

[Ghasem.Bashiri]

Based on ALPEMA and API standard, temperature difference between process streams within cold box (Plate-fin) exchanger should be maximum 50 for single phase and 30 for two phase. 

It is possible to ignore such recommendation?

 

API 668:

 

7.4.3 The plate-fin heat exchanger shall be designed for the following maximum temperature differences between streams at any point in the heat exchanger: a) 50 °C (90 °F) for single-phase streams with steady-state operating conditions; and 30 °C (54 °F) for two-phase streams or those with transient or cyclic operating conditions.

[ChEf]

A brazed aluminum heat exchanger shall be designed according to the temperature differences allowed by the standards, to guarantee its mechanical integrity.

In case you have a greater temperature difference, I would suggest a printed circuit heat exchanger.

[Pilesar]

Brazed aluminum heat exchanger standards in ALPEMA are based on consensus from the major manufacturers. You can abuse these exchangers at the risk of shortened life which is difficult to predict precisely. Evaluate the risk as there is significant lead time for a replacement exchanger. Depending on the service, consider partially bypassing the exchanger to keep the internal temperatures close.

[Ghasem.Bashiri]

In an existing plant we have deviation from ALPEMA recommendaiton for temperature difference.