(Solved): An evaporator is used to concentrate 10,000 lb/hr of a 20% solution of NaOH in water at 140oF using ...

An evaporator is used to concentrate 10,000 lb/hr of a 20% solution of NaOH in water at 140^oF using saturated steam at 25 psia at a rate of 7,000 lb/hr. The OHTC is 275 BTU/hr-ft²-^oF when the pressure in the vapor is 1.7 psia. The steam economy is

A. 0.72

B. 0.86

C. 0.99

D. 0.62