【2018年最新整理】化工原理.ppt

A wet material containing moisture content of 50wt% on a wet basis is dried to 6wt% in a continuous countercurrent drier. The moist air leaves the drier at t2=38℃ and H2=0.034kgH2O/ kg dry air and part of it recirculated and mixed with the fresh air having the temperature t0=25℃, humidityH0=0.005kgH2O /kg dry air before entering a preheater. The ratio of recirculated dry air to the mixed dry air is 0.8. Calculate the amount of fresh air and rate of heat transfer in the preheater when the wet material is fed to the dryer at rate of 1000kg/h on assumption that the dryer operates under the condition of isenthalpic process. Azeotropic Distillation Differences between the azeotropic distillation and extractive distillation 9.6 Plate Efficiencies Overall plate efficiency Murphree efficiency Chapter 11. 11.1.1. Purposes of Drying 11.1.2. General Methods of Drying 11.2. EQUIPMENT FOR DRYING 11.2.1. Tray Dryer 11.2.2. Vacuum-Shelf Indirect Dryers 11.2.3.ContinuousTunnel Dryers 11.2.3. Rotary Dryers 11.2.4. Drum Dryers 11.2.5. Spray Dryers 11.2.6.Flash Dryer VAPOR PRESSURE OF WATER AND HUMIDITY Humidity and Humidity Chart 1. Definition of humidity 2. Percentage humidity 3. Percentage relative humidity The percentage humidity is nearly equal to the relative humidity if the partial pressure of vapor in air is very low 4. Dew point of an air–water vapor mixture The temperature at which a given mixture of air and water vapor would be saturated is called the dew-point temperature 5. Humid heat of an air–water vapor mixture (11.3-6) 6. Humid volume of an air–water vapor mixture 7. Total enthalpy of an air–water vapor mixture 8. Humidity chart of air–water vapor mixtures Adiabatic Saturation Temperatures This means that the total enthalpy of the entering gas mixture = enthalpy of the leaving gas mixture. Wet Bulb Temperature This means that the adiabatic saturation temperature is approximately equal to wet bulb temperature. EQUILIBRIUM MOISTURE CONTENT OF MATERIALS Afte