A stream of 220kmol/h of a binary mixture containing benzene and toluene (45 mol% benzene) needs to be distilled to provide its components in high purity. A column of dishes with reflux (fractional distillation) will be used for the service. It is desired to obtain 97.5% pure benzene as the top product and 98% toluene in the bottom product (data on a molar basis). Benzene and toluene form an ideal liquid solution, the column will be operated at about 1atm, with relative volatility corresponds to 2.5. A reflux ratio of 3.5mol for each mole of distillate (3.5:1) will be used. The latent heats of benzene and toluene at the specified pressure are 7.38 and 7.96 cal/mol, respectively. A– Calculate the number of equilibrium stages necessary for the operation of the column, considering that the feeding is made with liquid at the bubble point (saturated liquid). with use of graphics . B– Redo item A, but now consider that the feed is in the form of steam at the dew point. Also evaluate what happens with the minimum reflux for this new feeding condition. C – Redo item A, but assume that the feed stream is in liquid form, but that 2/3 form vapor by flash effect for the feed plate conditions. Also evaluate what happens with the minimum reflux for this new feeding condition. l – Redo item A, but consider that the reflux ratio is 8:1.
A stream of 220kmol/h of a binary mixture containing benzene and toluene (45 mol% benzene) needs to be distilled to provide its components in high purity. A column of dishes with reflux (fractional distillation) will be used for the service. It is desired to obtain 97.5% pure benzene as the top product and 98% toluene in the bottom product (data on a molar basis). Benzene and toluene form an ideal liquid solution, the column will be operated at about 1atm, with relative volatility corresponds to 2.5. A reflux ratio of 3.5mol for each mole of distillate (3.5:1) will be used. The latent heats of benzene and toluene at the specified pressure are 7.38 and 7.96 cal/mol, respectively.
A– Calculate the number of equilibrium stages necessary for the operation of the column, considering that the feeding is made with liquid at the bubble point (saturated liquid). with use of
graphics .
B– Redo item A, but now consider that the feed is in the form of steam at the dew point. Also evaluate what happens with the minimum reflux for this new feeding condition.
C – Redo item A, but assume that the feed stream is in liquid form, but that 2/3 form vapor by flash effect for the feed plate conditions. Also evaluate what happens with the minimum reflux for this new feeding condition.
l – Redo item A, but consider that the reflux ratio is 8:1.
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