化工原理ppt課件(參考版)
2025-01-20 07:12本頁面
【正文】 that is, xc ≠ xD. ? The partial condenser is therefore equivalent to an additional theoretical stage Bottom plate and reboiler ? The vapor leaving the reboiler is in equilibrium with the liquid leaving as bottom product. Condition of feed ? Effects of different conditions of feed on distillation process ? Then q has the following numerical limits for the various conditions: ? Cold feed, q 1 ? Feed at bubble point (saturated liquid), q = 1 ? Feed partially vapor, 0 q 1 ? Feed at dew point (saturated vapor), q = 0 ? Feed superheated vapor q 0 qFLL ??? FqVV )1( ????Feed line 11 ????qxxqqy FConstruction of operating lines Feed plate location ? The optimum position of feed plate, the triangle representing the feed plate straddles the intersection of the operating lines. Minimum number of plates ? Total reflux and minimum number of plates 1ln)1()1(lnm i n ?????DBBDxxxxNMinimum reflux ? At a minimum value, called the minimum reflux ratio, the number of plates bees infinite. ? Concave downward ? Concave upward Optimum reflux ratio ? It is a minimum at a definite reflux ratio not much greater than the minimum reflux. This is the point of most economical operation, and this ratio is called the optimum reflux ratio. ? In ordinary situations, the minimum on the total cost curve will generally occur at an operating reflux ratio of from to times the minimum. Number of ideal plates at operating reflux Special Cases for Rectification Using McCabe– Thiele Method ? Stripping distillation ? Enriching distillation ? Rectification with direct steam injection ? Multiple feeds and sidestreams Azeotropic Distillation ? Differences between the azeotropic distillation and extractive distillation Plate Efficiencies ? Overall plate efficiency ? Murphree efficiency Chapter 11. ? . Purposes of Drying ? . General Methods of Drying ? . EQUIPMENT FOR DRYING ? . Tray Dryer ? . VacuumShelf Indirect Dryers ? Dryers ? . Rotary Dryers ? . Drum Dryers ? . Spray Dryers ? Dryer VAPOR PRESSURE OF WATER AND HUMIDITY Humidity and Humidity Chart 1. Definition of humidity AAgAggAApPppppMpMH????2. Percentage humidity 100??sp HHH3. Percentage relative humidity 100AsR ppH ?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 dewpoint temperature 5. Humid heat of an air–water vapor mixture Hccc wa i
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