$7.20\%($by wt$.)$ solution of sodium hydroxide to a $50\%$ solution. The dilute solution at $1093$ deg C is to be fed to the evaporator at the rate of $18143$ Kg$/$hr$.$ for heating purposes; a saturated steam at $10$o C is used. Sufficient condenser area is available to maintain a pressure of $667$ Kg$/$M$2$ in the vapor space of the evaporator. On the basis of overall heat transfer coefficients of $300$ kilocalorie $/$ hour$/$ square meter$/\backslash$deg C$.$ Compute a$)$ Heating area required. b$)$ Steam consumption and steam economy.