Revisiting Example 20.18, by how much should the steam temperature be increased in order to achieve the 15% increase in boil-up rate for the case when the process-and steam-side heat transfer coefficients are approximately equal?

Assume that this is a nonfouling service, the conduction resistance of the tube wall may be assumed negligible, and D_i ≅ D_o. In addition, the process fluid may be assumed to be in the convective boiling regime.

Example 20.18

A reboiler for a column is supplied with saturated steam (in shell) at a temperature of 145°C and reboils the bottom product (in tubes) that leaves the column at 122°C. It is desired to increase the boil-up rate by 15% from the design case. How can this change be accomplished?