ASPEN Design of Distillation

ASPEN Instruction

RadFrac

rigorous model for simulating all types of multistage

vapor-liquid fractionation operations

Chapter 5Profiles for Multicomponent

Distillations

Feed is 1 kmole/hr of 0.233 mole fract benzene, 0.333 toluene, and 0.434 cumene, Feed stage is 10 tray above reboiler, and there are 19 equilibrium stages plus a partial reboiler with 99% recovery of benzene in distillate. Pressure is 101. 3 kPa. L/D=1

Feed is .125 benzene, 0.225 toluene, 0.375 xylene, and 0.275 cumene, with 99% recovery of toluene in distillate.

DSTWU

DSTWU performs shortcut design calculations for single-feed,

two-product distillation columns with a partial or total condenser.

DSTWU uses thismethod/correlation

To estimate

Winn Minimum number of stages

Underwood Minimum reflux ratio

Gilliland Required reflux ratio for a specified number ofstages or the required number of stages for aspecified reflux ratio

Homework

• Using the Fenske-Underwood-Gilliland method (Case B), find– Nmin

– RRmin

– Actual RR, N, and distribution of NK’s

• Use DSTWU for same things

• Verify with RADFRAC

• For the following system

Homework

A distillation column with a partial reboiler and a total condenser is being used to separate benzene, toluene, and cumene. The feed is 40mole% benzene, 30% toluene, and 30% cumene and is input as saturated vapor. We desire 95% recovery of toluene in the distillate and 95% recovery of cumene in the bottoms. The reflux is returned as a saturated liquid. Pressure is 1 atm. Find the number of stages and reflux ratio and the optimum feed location

180°F

Where do we start?

Need Temperature or pressure of column – can we use cooling water

Need to know number of trays and Reflux – how?

Two models, we will use DSTWU

Does the column work?

Put into RadFrac and adjust