A solution with a specific heat of 4.187 kJ/kg.K and no boiling point rise is fed to a standard type evaporator group with iso-directional, double-effect and equal heating surface area, with a flow rate of 18 tons/hour. In this system where half of the fed solution is evaporated, the entire heat transfer coefficient of the 2nd effect is of the entire heat transfer coefficient of the 1st effect. The feed current enters the system at the boiling temperature in the 1st effect. The saturated water vapor used as the heating medium is sent to the heating chamber of the 1st effect at 395 K, and the solution boils at 373 K in the 2nd effect. Calculate the heating steam expenditure by making the appropriate assumptions.