Prof. Mohammad Asif Room 2B45, Building 3 Tel: Department of Chemical Engineering Separation Processes – 1 Module -3 DRYING

Course Outline Text-BookTimeMain TopicModule Separation Process Principles, 3rd Edition ISBN: J. Seader, E. Henley, D. Roper 6 weeksMembrane separation processes 1 Transport Processes and Separation Process Principles, 4 edition Prentice Hall ISBN: C. J. Geankoplis 4 weeksHumidification2 4 weeksDrying3

Lecture Schedule EventTopicsDatesWeek Introduction1 Module Test 1: MondayModule Module 211 Test 2: MondayModule 312 Module 313 Module 314 Module 315 General Exams16 Final Exams17

Module 2: Humidification Introduction, definitions and humidity charts Theory of adiabatic saturation and wet bulb temperatures Design of cooling towers Cooling Tower of Nuclear Power

Module 3: Drying Introduction to drying Drying curves and phases Calculation methods Material and heat balances for dryers Equations for various types of dryers Drying equipment Phosphate rotary dryer Potash rotary dryer Nickel ore rotary dryer

A heater-dryer arrangement with air recirculation is shown in the above figure. The flow of different streams is mentioned. In the following eight questions, circle the correct answer. Note that G represents the dry air flow in kg per hour

The wet feed material to a continuous drier contains X 1 = 10 wt% water on a dry basis (kg water per kg dry solid and dried to X 2 = 5 wt% by countercurrent air flow. The feed rate is Ls = 500 kg dry solid/h. Fresh air to the system is at T G1 = 25.6 C and has a humidity of H 1 =0.007 kg water/kg dry air. The moist air leaves the dryer at T G4 = 37.8 C and H 4 =0.022 and a part of it is re-circulated and mixed with the fresh air before entering a heater. The heated mixed air enters the dryer at T G3 = 95 C and H 3 =0.01. The solid enters at T S1 = 35 C and leaves at T S2 = 65 C. The heat capacity of the dry solid is 1.5 kJ/(kg dry solid.K) and the heat capacity of the liquid moisture is 4.2 kJ/(kg H 2 O.K). Calculate: Flow rate of the air through the dryer Flow arte of the recycled air Heat loss from the dryer in kW Flow rate of wet solid feed entering the dryer in kg total solid per hour