Page 141 - Separation process engineering

is L /D = 4, and reflux is returned as a saturated liquid. Find D, B, Q , and Q .
c
R
0
F2.* A mixture of water and ammonia is to be distilled in an ordinary distillation system (Figure 3-8)
2
at a pressure of 6 kg/cm . The feed is 30 wt % ammonia and is at 20 °C. We desire a distillate
product that is 98 wt % ammonia and a 95% recovery of the ammonia in the distillate. The
external reflux ratio is L /D = 2.0. Reflux is returned at −20 °C. Find D, B, x , Q , and Q per
0 B R c
mole of feed.

G. Computer Problems

G1. Solve for Q and Q in Problem 3.D1 with a process simulator.
c R
a. Part a.

b. Part b.

Note: With Aspen Plus, use RADFRAC (see Appendix to Chapter 6, Lab 3) with an arbitrary (but
large) number of stages and feed location = N/2. Do calculation for D by hand and input correct
values for D and L/D (or V/B).
G2. [This problem should be done after studying the Appendix A of Chapter 4.] Solve Problem 3.D6
using AspenPlus to find Q and Q . To do this, do a hand calculation to find the value of D. Then
R
c
arbitrarily set N = 40 and N feed = 20 in RADFRAC and do the simulation.