Fifty thousand lb/h of a 20 wt% aqueous solution of NaOH at 120°F is to be fed to an evaporator operating at 3.7 psia, where the solution is concentrated to 40 wt% NaOH. The heating medium is saturated steam at a temperature 40°F higher than the exiting temperature of the caustic solution. Determine the: 

(a) Boiling-point elevation of the solution; 

(b) Saturated-heating-steam temperature and pressure; 

(c) Evaporation rate; 

(d) Heat-transfer rate; 

(e) Heatingsteam flow rate; 

(f) Economy; and .

(g) Heat-transfer area if U = 300 Btu/h-ft²-°F.