A continuous co-current flow direct heat dryer is to be used to dry Epsom crystals (M9SO4.7H2O)....

 

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A continuous co-current flow direct heat dryer is to be used to dry Epsom crystals (M9SO4.7H2O). The feed to dryer (a filter cake from a vacuum dryer) consists of 2854 Ib/h crystals (dry basis) with a moisture content (Xin) of 25.8 wt% dry basis at 85F and 14.7 psia. Air enters the dryer at 14.7 psia with dry and wet bulb temperatures of 250F and 117F respectively. The final moisture content of the dried crystals is to be 1.5wt% dry basis at a temp of no more than 118F to prevent crystal decomposition. Determine: 2.1. Rate of moisture evaporation 2.2. The outlet temperature of air 2.3. The rate of heat transfer 2.4. The entering air flow rate A continuous co-current flow direct heat dryer is to be used to dry Epsom crystals (M9SO4.7H2O). The feed to dryer (a filter cake from a vacuum dryer) consists of 2854 Ib/h crystals (dry basis) with a moisture content (Xin) of 25.8 wt% dry basis at 85F and 14.7 psia. Air enters the dryer at 14.7 psia with dry and wet bulb temperatures of 250F and 117F respectively. The final moisture content of the dried crystals is to be 1.5wt% dry basis at a temp of no more than 118F to prevent crystal decomposition. Determine: 2.1. Rate of moisture evaporation 2.2. The outlet temperature of air 2.3. The rate of heat transfer 2.4. The entering air flow rate