A forward feed double effect evaporator concentrates $200$ kg$/$h of solution from $10\%$ to $50\%$ by weight solids. The feed temperature is $313$ K and the gauge pressures of the steam in the calandria$$s are $300$ kN$/$m$2$ and $60$ kN$/$m$2$ respectively. The condenser operates at a pressure of $14\mathrm{.}7$ kN$/$m$2.$

The heat transfer area in each effect is $14\mathrm{.}0$ m$2.$

Using the data given, calculate:$-$

a$)$ The steam economy

b$)$ The heat transfer coefficients in each effect

Data

Take Cp for all solutions as $4\mathrm{.}2$ kJ$/$kg K

Boiling point elevation in effects $1$ and $2$ are $5\backslash$deg and $12\backslash$deg C respectively.

Atmospheric pressure $=101.$A backward feed double effect evaporator is to be used to produce $1\mathrm{.}26k\frac{g}{s}$ of

concentrated liquor from a feed solution of $6\mathrm{.}3k\frac{g}{s}.$ Using the data given below,

calculate:

a$)$ The evaporation rate in each effect

b$)$ The steam consumption

c$)$ The heating surface in each effect

Data

Feed Temperature $=38C$

Specific heat capacity of all liquids $=4\mathrm{.}18k\frac{J}{k}gK$

Neglect any boiling point rise.