Rigorous methods, distillation

RIGOROUS METHODS FOR MULTICOMPONENT DISTILLATION-TYPE SEPARATIONS... 

Another evident trend is the application of mechanical computers for the rapid calculation of distillation problems. At least two papers have already appeared, one by Weil (57) on the use of an electronic computer, and the other by Rose and Williams (47) on the application of the IBM card punch technique. If a short rigorous method is not forthcoming, machine calculations may be the answer to accurate design of fractionating equipment. 

The initial total flow rate and temperature profiles can make the difference between success and failure of a rigorous method. Usually for distillation columns, the condenser and reboiler temperatures are estimated and a calculation that assumes constant molal overflow Sec. 2.2.2) is used to initialize tbe internal vapor and liquid flow... 

Multi-component batch distillation computation time can be excessive with rigorous methods, especially for problems that require multiple runs, such as optimization, and for online applications. It is desirable to have shortcut alternatives for such situations. 

The approximate method gives an overall separation reasonably close to that computed by the rigorous method. This agreement is aided by the problem selected—distillation of a homologous series of hydrocarbons, a fairly ideal case. Even so, it is clear that some adjustment in the input conditions for the rigorous method is necessary if the original specifications are to be met. 

All the operations described here must be carried out under a rigorously dry, oxygen-free nitrogen atmosphere, using conventional Schlenk-tube techniques.4 Solvents should be purified by conventional methods, distilled and stored under nitrogen. 

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