Spray drying is a process in which a liquid containing dissolved or suspended solids is injected into a chamber through a spray nozzle or

centrifugal disk atomizer. The resulting mist is contacted with hot air, which evaporates most or all of the liquid, leaving the dried solids

to fall to a conveyor belt at the bottom of the chamber.

$W_w=70\mathrm{.}0\%,P_i=-50\mathrm{.}0cm{H}_{2}O$

$T_i=167C,T_O=83\mathrm{.}0C$

$V_o^{}=323\frac{m^3}{m}i{n}^2,x_w=0\mathrm{.}14$

Powdered milk is produced in a spray dryer $6\mathrm{.}0m$ in diameter by $6\mathrm{.}0m$ high. Air enters at $167C$ and $-50\mathrm{.}0cm{H}_{2}O($gauge$).$ The milk

fed to the atomizer contains $70\mathrm{.}0\%$ water by mass, all of which evaporates. The outlet gas contains $14\mathrm{.}00$ mole$\%$ water and leaves the

chamber at $83\mathrm{.}0C$ and $1$atm $($absolute$)$ at a rate of $323\frac{m^3}{m}in.$

Calculate the production rate of dried milk and the volumetric flow rate of the inlet air. Estimate the upward velocity of air $(\frac{m}{s})$ at the

bottom of the dryer.

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