Wet food pulps from the presses containing 60 percent by mass water are to be dried to 5 percent moisture in a rotary dryer, by contacting with hot air. The hot air flows counter currently and is prepared by mixing the ambient air with a part of the exit air from dryer, which is then heated to 800 ̊C. From design consideration the humidity of the air at the dryer inlet and at the exit should be 0,015 and 0,03 kg H2O per kg bone dry air, respectively. On a specific day when the humidity of the ambient air is 0,009 kg H2O/kg BDA, determine; a. Draw the flowchart of the problem b. The amount of ambient air to be supplied per kg of wet pulp c. Mass of exit air that must be recycled to the dryer inlet per kg of dried product.

3. Wet food pulps from the presses containing 60 percent by mass water are to be dried to 5 percent moisture in a rotary dryer, by contacting with hot air. The hot air flows counter currently and is prepared by mixing the ambient air with a part of the exit air from dryer, which is then heated to 800 ̊C. From design consideration the humidity of the air at the dryer inlet and at the exit should be 0,015 and 0,03 kg H2O per kg bone dry air, respectively. On a specific day when the humidity of the ambient air is 0,009 kg H2O/kg BDA, determine;

a. Draw the flowchart of the problem

b. The amount of ambient air to be supplied per kg of wet pulp

c. Mass of exit air that must be recycled to the dryer inlet per kg of dried product.