Practice-Exams-2_13224 - Exam 1 1. Drying is the last step...

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1 Exam 1 1. Drying is the last step in the production of many crystalline products and powders, including food products and pharmaceuticals. A counter-current drying process, where wet powder and dry air flow in opposite directions, is shown below. Part of the exit air is recycled back and mixed with the inlet air to generate air with the desired moisture content. The water content in the different streams are: Inlet air (mol%) – 0.0132; Wet powder (mass%) – 0.20; Exit air (mol%) – 0.263; Dried powder (mass%) – 0.05; Air entering the dryer (mol%) – 0.066 Assuming a basis of 1000 kg/h of wet powder fed to the dryer, calculate the inlet and exit air flow rates (kg/h) and the recycle rate (kg/h). The MW of air can be assumed to be 29 g/mol. 2. Ethylene (C 2 H 4 ) and Air are mixed (2:1 mol ratio of ethylene to oxygen) and partially oxidized in a reactor to form Ethylene Oxide (C 2 H 4 O). In a side reaction, the ethylene is undergoes complete oxidation. The fractional conversion of ethylene is 25% and the reactor outlet contains no oxygen. For an ethylene oxide product flow rate of 2000 kmol/h, calculate the reactor feed rate and composition using the extent of reaction method. 3. Ethane is chlorinated in a continuous reactor to produce monochloroethane (MCE) and hydrogen chloride. In addition, some of the MCE can also react with chlorine to form dichloroethane (DCE) and hydrogen chloride. C 2 H 6 + Cl 2 C 2 H 5 Cl + HCl C 2 H 5 Cl + Cl 2 C 2 H 4 Cl 2 + HCl A mixture containing 60 mol% ethane and 40 mol% chlorine is fed to a reactor in which all of the chlorine is reacted. In the exit stream from the reactor there are eight moles of MCE per mole of DCE. The stream leaving the reactor is cooled and all the MCE and DCE are liquefied and
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This note was uploaded on 12/12/2010 for the course CHEN 204 taught by Professor Staff during the Fall '08 term at Texas A&M.

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Practice-Exams-2_13224 - Exam 1 1. Drying is the last step...

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