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 the liquid, leaving the dried solids to fall to a conveyor belt at the bottom of the chamber. Powdered milk is produced in a spray dryer 6 m in diameter by 6 m high (Figure 1). The air enters at 167 C and -40 cmHO. The milk fed to the atomizer contains 70% water by mass, all of which evaporates. The outlet gas contains 12 moles% water and leaves the chamber at 83 C and 1 atm (absolute) at a rate of 311 m/min. Calculate. a. the production rate of dried milk and b. the volumetric flow rate of the inlet air. Milk (70% HO) Inlet air 167C, -40 cm HO Dried milk (15 marks) (15 marks) Wet air 311 m/min @ 83C, 1 atm Figure 1: spray drying of milk.