Column distillation optimum feed stage

A column is to be designed to separate 1000 moles/hr of a binary mixture of benzene (QH ) and toluene ( 7 ). The feed will contain 40% benzene and 60% toluene. A distillate that is 99% benzene and a bottoms that is 1% benzene are desired at a reflux ratio of 3 to 1. For this mixture, the average value of relative volatility (a) is 2.50. Estimate the number of equilibrium stages at this reflux ratio and the optimum feed stage location. 

D20. A distillation column with a total condenser and a partial reboiler is separating ethanol and water at 1 kg cm pressure. Feed is 0.32 mole fraction ethanol and is at 30° C. Feed flow rate is 100 kmol/h. The distillate product is a saturated liquid, and the distillate is 80 mol% ethanol. The condenser removes 2,065,113 kcal/h. The bottoms is 0.04 mole fraction ethanol. Assume that CMO is valid. Find the number of stages and the optimum feed stage location. 

D29. A distillation column will use the optimum feed stage. A liquid side stream is withdrawn on the third stage below the total condenser at a rate of 15.0 kmol/h. The feed is a two phase mixture that is 20% vapor. Feed to the column is 100.0 kmol/h. The feed is 60.0 mol% acetone and 40.0 mol%... 

El. A system known as a punp-around is shown below. Saturated liquid is withdrawn from stage 2 above the partial reboiler, and the liquid is returned to stage 3 (assume it is still a saturated liquid). Pump-around rate is P = 40.0 kmol/h. The column is separating methanol and water at 101.3 kPa. The feed flow rate is 100.0 kmol/h. The feed is 60.0 mol% methanol and 40.0 mol% water. The feed is saturated liquid. We desire a bottoms product that is 2.5 mol% methanol. The distillate product should be 95.0 mol% methanol. The column has a total condenser and the reflux is a saturated liquid. Assume CMO. Use (L/D) = 2.0 x (L/D)Tnin- Data are given in Table 2-7. Find Xp, the optimum feed stage and total number of equilibrium stages required. 

E3. A distillation column with at total condenser and a total reboiler is separating ethanol from water. Reflux is returned as a saturated liquid, and boilup is returned as a saturated vapor. CMO can be assumed. Assume that the stages are equilibrium stages. Column pressure is 1 atm. A saturated liquid feed that is 32 mol% ethanol is fed to the column at 1000 kmol/h. The feed is to be input on the optimum feed stage. We desire a distillate conposition of 80 mol% ethanol and a bottoms conposition that is 2 mol% ethanol. A liquid side stream is removed on the eighth stage from the top of the column at a flow rate of S = 457.3 kmol/h. This liquid is sent to an intermediate reboiler and vaporized to a saturated vapor, which is returned to the column at its optimum feed location. The external reflux ratio is Lq/D = 1.86. Find the optimum feed locations of the feed and... 

HI. [VBA required] Using the spreadsheet in Appendix B of Chapter 4 or your own spreadsheet, solve the following problem. A methanol water mixture is being distilled in a distillation column with a total condenser and a partial reboiler. The pressure is 1.0 atm, and the reflux is returned as a saturated liquid. The feed rate is 250 kmol/h and is a saturated vapor. The feed is 40 mol% methanol. We desire a bottoms product that is 1.1 mol% methanol and a distillate product that is 99.3 mol% methanol. L/D = 4.5. Find the optimum feed stage, the total number of stages, D and B. Assume CMO is valid. Equilibrium data are available in Table 2-7. Use Excel to fit this data with a 6th-order polynomial. After solving the problem, do What if simulations to see what happens if the products are made purer and if L/D is decreased. 

El. We wish to distill a mixture of ethane, propane, n-butane. The column has a partial reboiler and a partial condenser and operates at 400 kPa. The feed flow rate is 200 kmol/h. The feed is a saturated liquid and is 22 mol% ethane, 47 mol% propane, and 31 mol% n-butane. We wish to recover 97% of the ethane in the distillate and 99% of the propane in the bottoms. The reflux is a saturated liquid, and the external reflux ratio Lq/D = 3.0. Find the optimum feed stage and the total... 

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-... 

The second column receives the distillate from column 1 as a saturated liquid feed at one atm pressure. The second column is at 1.0 atm pressure and operates with D = 25.0 and L/D = 4.0. It has a total condenser and a ketde reboiler. There are 34 equilibrium stages in the column. Find the optimum feed stage location. For column 2 report the following ... 

D21. A distillation column is separating water fromn-butanol at 1 atmosphere pressure. Equilibrium data are in Table 8-2. The distillation system is similar to Figure 8-3A and has a partial reboiler, a total condenser and a liquid-liquid settler. The bottom layer from the settler (rich in water with x = 0.975) is taken as the distillate product. The top layer (x = 0.573) is returned to the column as a saturated liquid reflux. The feed is 40.0 mol% water, is a saturated vapor and flows at 500.0 kmol/h. The bottoms is 0.04 mole frac water. Use a boilup ratio of V/B = 0.5. Assume CMO is valid. Step off stages from the bottom up. Find the optimum feed stage location and the total number of equilibrium stages needed. 

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 ... 

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 ... 

The feed, at a flow rate of 100 kmol/h, is sent as saturated vapor to the distillation column. The column is equipped with a partial condenser with a vapor product, and a reboiler. For a solvent rate of 500 kmol/h, it is required to determine the required number of equilibrium stages and the optimum feed location for a reflux ratio of 1.5 times the minimum. The McCabe-Thiele method may be used on a solvent-free basis. 

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. 

A distillation column is separating 100 mol/s of a 30 mol% acetone, 70 mol% methanol mixture at atmospheric pressure. The feed enters as a saturated liquid. The column has a total condenser and a partial reboiler. We desire a distillate with an acetone content of 72 mol%, and a bottoms product with 99.9 mol% methanol. A reflux ratio of 1.25 the minimum will be used. Calculate the number of ideal stages required and the optimum feed location. VLE for this system is described by the modified Raoult s law, with the NRTL equation for calculation of liquid-phase activity coefficients, and the Antoine equation for estimation of the vapor pressures. 

Initially, the total feed is split equally between the two columns. This is achieved in the Splitter labeled Tl on the flowsheet shown in Figure 5.33. Two Design SpecA ary are set up in each column to adjust distillate flow rate and reflux ratio to attain the 99.9 mol% product purities of all foiu streams. The optimum feed tray location is determined by finding the feed stage that minimizes reboiler heat input. In column Cl, it is Stage 19. In column C2, it is Stage 18. 

A. Define. It helps to draw a schematic diagram of the apparatus, particularly since a new type of distillation is involved. This is shown in Figure 4-15. We wish to find the optimum feed plate location, Np, and the total number of equilibrium stages, N, required for this separatiom We could also calculate Q, D, B, and the steam rate S, but these were not asked for. We assume that the column is adiabatic since it is well insulated. 

We wish to separate ethanol from water in a distillation column with a total condenser and a partial reboiler. We have 200 kmol/h of feed 1, which is 30 mol% ethanol and is saturated vapor. We also have 300 kmol/h of feed 2, which is 40 mol% ethanol. Feed 2 is a subcooled liquid. One mole of vapor must condense inside the column to heat up 4 moles of feed 2 to its boiling point. We desire a bottoms product that is 2 mol% ethanol and a distillate product that is 72 mol% ethanol. External reflux ratio is Lq/D = 1.0. The reflux is a saturated liquid. Column pressure is 101.3 kPa, and the column is well insulated. The feeds are to be input at their optimum feed locations. Find the optimum feed locations (reported as stages above the reboiler) and the total number of equilibrium stages required. 

D15. A partial condenser takes vapor leaving the top of a distillation column and condenses a portion of it. The vapor portion of mole fraction y is removed as the distillate product. The liquid portion of mole fraction Xq is returned to the column as reflux. The liquid and vapor leaving partial condensers and partial reboilers can be assumed to be in equilibrium, A distillation column with a partial condenser and a partial reboiler is separating 300 kmol/h of a mixture that is 30 mol% ethanol and 70 mol% water and is a saturated liquid. We desire a 98% recovery of the ethanol in the vapor distillate and an 81% recovery of water in the bottoms. If Lg/D = 2.0 find the optimum feed location and the total number of equilibrium stages. 

E5. A distillation column is separating a feed that is 30 mol% acetone and 70 mol% ethanol. The column has a partial condenser. Operation is at p = 1 atm The feed flow rate is 1000 kmol/day, the feed is a saturated liquid, and feed is input at the optimum location. We desire a distillate that is 90 mol% acetone and a bottoms that is 10 mol% acetone. Use a boilup ratio of V/B = 1.25. On the fourth stage above the partial reboiler, a vapor sidestream with flow rate S = 200 kmol/day is withdrawn and then condensed to a saturated liquid, which is returned to the column as feed at the optimum location. Assume CMO. Find the mole fraction of vapor side stream y, optimum feed... 

G2. [Note This problem is quite extensive.] Biorefineries producing ethanol by fermentation have several distillation columns to separate the ethanol from the water. The first column, the beer still, is a stripping column that takes the dilute liquid fermenter product containing up to 15% solids and produces a clean vapor product that is sent to the main distillation column. The main column produces a distillate product between about 65 mole % and the ethanol azeotrope, and a bottoms product with very litde ethanol. The calculated diameter of the main distillation column is much greater at the top than elsewhere. To reduce the size and hence the cost of the main column, one can use a two-enthalpy feed system split the vapor feed into two parts and condense one part, then feed both parts to the main column at their optimum feed locations. This method reduces the vapor velocity in the top of the column, which reduces the calculated diameter however, a few additional stages may be required to obtain the desired purity. 

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