A three-stage evaporator is fed with 1.25 kg/s of liquor which is concentrated from 10 % to 40 % solids. The heat transfer coefficients may be taken as 3.1, 2.5, and 1.7 kW/m2.K. Calculate the steam at 170 kN/m2 required per second and the temperature distribution in the three effects if the feed stream is at 294 K. The boiling point for the third effect is 325 K and the liquor has no boiling point rise. Determine: (i) the temperature distribution, (T₁, T₂, T₃) (ii) the area of heating surface required in each effect (A₁, A₂, A₃) (iii) the steam economy (iv) the heat load on the condenser

where, Di is mass flow rate of steam at effect i, F is feed flow rate, i is latent heat of water evaporation at Ti, and Ti is temperature at effect i.

The heat balance equations for each effect are given as below: -SecondEffect:D00=FCP(T1TF)+D11D22=(FD1)CP(T1T2)+D11D33=(FD1D2)CP(T2T3)+D22