Page 203 - Chemical engineering design

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and fresh feed vectors; solve the equations; and use the results to calculate and check the
values of any stream composition. CHEMICAL ENGINEERING
Once the spreadsheet has been set up it is easy to change the values of the split fractions
and fresh feeds, and iterate until the design constraints for the problem are satisfied.
The sample problem was solved using an inexpensive, but versatile, spreadsheet package
1
“AS-EASY-AS” . The procedure used is illustrated below.
Procedure

Step 1: Set up the table of split-fractions and fresh feeds, Figure 4.15.
A] . ... .. ..A/... ... ..B/... .. ...C/... .. ...D/... .. ...E/... .. .. .F/.. ... .. .G/.. ... .. .H
1
2 MASSBAL EXAMPLE USING SPREAD SHEET “AS-EASY-AS”
3 TO SOLVE EQUATIONS
4
5
6 Split fraction coefficients and fresh feeds
7
8 alpha / k 1 2 3 4
9
10 21k 0.10 1.00 1.00 1.00
11 32k 0.10 0.20 1.00 0.05
12 42k 0.90 0.80 0.00 0.95
13 43k 0.99 0.99 0.00 0.99
14 54k 0.99 0.01 1.00 0.99
15 15k 0.99 0.01 1.00 0.05
16
17 g101 g202 g203 g304
18
19 mol 100.00 98.00 98.00 200.00
20

Figure 4.15.
Step 2: Set up an identity matrix of the dimensions needed, n ð n; a matrix with 1’s
on the leading diagonal and 0’s elsewhere. For this problem there are 5 unis so a 5 ð 5
matrix is needed, Figure 4.16.
A] . ... .. ..A/... ... ..B/... .. ...C/... .. .. .D/... .. .. .E/.. ... .. .F/.. .. ... .G/.. .. ... .H
20
21
22 Identity matric
23
24 1 2 3 4 5 g Flows
25
26 1 1.00 0.00 0.00 0.00 0.00 0.00
27 2 0.00 1.00 0.00 0.00 0.00 0.00
28 3 0.00 0.00 1.00 0.00 0.00 0.00
29 4 0.00 0.00 0.00 1.00 0.00 0.00
30 5 0.00 0.00 0.00 0.00 1.00 0.00
31
Figure 4.16.

1 AS-EASY-AS is copyright software developed by TRUIS Inc., North Andover, Massachusetts, USA.
Check their web site to download the latest version: www.truisinc.com.