Bituminous coal is dried in a continuous process where hot air at dry bulb temperature of 55C and wet bulb temperature of 22.5C is contacted with wet coal in a continuously Moving Belt Dryer (MBD). Wet coal is fed to the MBD at a rate of 1000.0 kg/h and contains 5.5 kg H2O/100 kg bone dry coal. Dried coal contains 0.5 kg H2O/100 kg bone dry coal as it exits the MBD. The hot air is adiabatically cooled in the MBD as it is humidified by the water vapour leaving the coal. Humidified air exiting the MBD is sent to a condenser operating at 1.0C. The air exiting the condenser is sent to a heater where it is heated to 55C and recycled back to the MBD in a closed loop cycle.

a) Draw a flowchart of the whole drying loop and label all the streams with process variables. [5 marks]

b) If the relative humidity of the air exiting the MBD is 70%, show the path taken by the air stream on the psychrometric chart provided separately, clearly labelling all the points of air entering to and exiting from each unit. [5 marks]

c) Calculate the mass (kg/h) of dry air circulating the drying loop and the volume (m3/h) of the hot air entering the MBD. [5 marks]

d) Calculate the rate of heat removal (kW) in the condenser and the rate of heat addition (kW) in the heater. [5 marks]