Fractionating columns optimum reflux ratio

A fractionation column operating at 101 kPa is to separate 30kg/hr of a solution of benzene and toluene containing 0.6 mass fraction toluene into an overhead product containing 0.97 mass fraction benzene and a bottoms product containing 0. mass fraction toluene. A reflux ratio of 3.5 is to be used. The feed is liquid at its boiling point, feed is on the optimum tray, and the reflux is at saturation temperature. 

Report the number of stages and the optimum feed stages in each column, the reflux ratios, the tenperatures at the top and bottom of each column (in K), the heat duties in the reboilers and condensers (kJ/s), the conpositions (in mole fractions) and flow rates of the three products and of the interconnecting stream (kmol/h), the column diameters, and any other information you consider to be relevant. If you use DSTWU or the Fenske-Underwood-Gilliland approach or a McCabe-Thiele diagram for the second column, conpare these results with RADFRAC. 

It is required to separate the benzene-toluene mixture of Example 6.1 into a benzene-rich distillate with 0.80 mole fraction benzene and a toluene-rich bottoms with 0.05 mole fraction benzene. The separation is to be made using a distillation column with 15 theoretical stages that include a partial condenser and a partial reboiler. Calculate the reflux ratio required to achieve the specified separation and determine the optimum feed location. What effect would lowering the number of stages to ten have on the reflux ratio and the optimum feed location ... 

We desire to use a distillation column to separate an ethanol-water mixture. The column has a total condenser, a partial reboiler, and a saturated liquid reflux. The feed is a saturated liquid of composition 0.10 mole fraction ethanol and a flow rate of 250 mol/hr. A bottoms mole fraction of 0.005 and a distillate mole fraction of 0.75 ethanol is desired. The external reflux ratio is 2.0. Assuming constant molar overflow, find the flowrates, the number of equilibrium stages, optimum feed plate location, and the liquid and vapor compositions leaving the fourth stage from the top of the column. Pressure is 1 atm. 

In these, the gas phase is suitably collected and subjected to the subsequent analytical determinations in a discontinuous fashion. Although the classical distillation systems have fallen into disuse since the advent of the advantageous gas chromatography, their automation has fostered the development of assemblies of some Interest. Chipperfleld et al. [2] reported a computer-controlled laboratory fractional column for small-scale preparations in which a microcomputer controls the column-jacket temperatures, boil-up rate and reflux ratio to achieve optimum separations. A schematic diagram of the dls-... 

H2. [VBA required] Either write your own program or use the program in Appendix A of Chapter 5 to solve the following problem, A feed of 100 mol/h of a saturated liquid that is 25 mol% A = benzene, 35 mol% B = toluene, and 40 mol% C = cumene is fed on the optimum feed plate to a distillation column that has a total condenser and a partial reboiler. Fractional recoveries of B (toluene) in the distillate of 0.9 and of C in the bottoms of 0.97 are desired. The relative volatilities are 2.25, Ogg = 1.0, and = 0.21. Use an external reflux ratio of L/D = 0.3. Find the optimum feed stage, the total number of stages, the fractional recovery of A (benzene) in the distillate, D and B. After solving the problem, try What if simulations to explore the effects of changing the feed concentrations, the fractional recoveries, L/D, and the relative volatility a B-... 

D23.100 kmol/h of a saturated vapor feed that is 25 mol% nitromethane (NM) and 75 mol% water is to be separated in a system with two distillation columns and a liquid-liquid separator. The feed is sent to column W that produces a water product that is 0.01 mole fraction NM. The boilup ratio in column W is 4. The optimum feed stage is used. The vapor from column W is condensed and sent to the decanter. The water phase from the decanter (0.086 mole fraction NM) is refluxed to column W. The NM phase from the decanter (0.312 mole fraction water) is sent to stripping column NM. The nitromethane product from the bottom of stripping column NM is 0.02 mole fraction water. The boilup ratio in column NM = 3.0. Assume both columns operate at 1.0 atm pressure, that CMO is valid, that both condensers are total condensers, and that both reboilers are partial reboilers. Equilibrium data are in Table 8-3. Find ... 

Shortcut Module The required input for the design mode consists of identification of the key components to be separated, specification of the fractional recoveries of each key conponent in the overhead product, the column pressure and pressure drop, and the ratio of actual to minimum reflux ratio to be used in the column. The simulator will estimate the number of theoretical plates required, the exit stream conditions (bottom and overhead products), optimum feed location, and the reboiler and condenser duties. 

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