Page 97 - Applied Process Design For Chemical And Petrochemical Plants Volume II

86 Applied Process Design for Chemical and Petrochemical Plants

2. Using ai and the component distribution line, esti-
mate % recovery of non-key components in distillate
and bottoms. where Ya = % recovery of i in distillate
Y~B = 9% recovery of i in bottoms
From the references [124, 1411: fi = total mols of component i in distillate and bottoms

log (di/bi) = a + b log ~i (8-173) Then Y~B = 100 - Y~D (8-174)

where di = mols of component i in distillate and di/bi = Y~D/ (100 - Y~D) (8-175)
bi = moles of component i in bottoms
ai = relative volatility of component i From Equation 8-174, Table 8-5 is constructed for select-
a, b = correlation constants ed values of di/bi at various values of YiD from 99.9% to
0.1%.
log (di/bi) vs. log a, gives a straight line (Figure EL50). By
superimposing a Y~D scale over the di/bi scale, Component Recovery Nomograph (Figure 8-50)

A nomograph is constructed by plotting di/bi vs. ai on
log-log graph paper and then superimposing a yiD scale
0.1 over the di/bi scale, according to the values given in Table
8 0.2
w.6 0.4
99.4 0.8 Table 8-5
99.2 0.8 Material Balance for Estimated Multicomponent
99.0 1 .o
98.5 1.5 Distillation Recoveries for Example 8-28 Using Method
98 2 of Yaws, Fang, and Pate1
97 8 ~ ~
96 4 Feed Composition, Relative *
94 6 Component Mol. Fr. volatility
92 8
90 10 0.05 3.5
85 15 0.20 3.0
- Light
.g 80 0.30 2.3
70 30 1 0.25 1 .o Heavy
e 0.15 0.83
=Bo 405 0.05 0.65
50 50
# 40 Distillate Recovery Recovery
b! 30 70 Component Desired, % Derived, %*
le f
20 80 A 99.72**
15 85
B 99.20**
10 C 95 -
8 -
6 94 D 5
4 96 E 1.30**
3 97 F 0.22*
2 98
Bottoms Recovery Recovery
1 .o 90.0 Component Desired, % Derived, %*
0.8 99.2
0.6 w.4 0.28**
0.4 99.6 0.80**
5 -
0.2 99.8 -
95
0.1 99.9 98.70**
0.2 0.3 0.4 O.! 5 0.6 0.8 1 2 3 4 5 6 99.78**
Relatlve volatilitypi
*See calculations
Figure 8-50. Estimation of recovery of non-key components using **From Figure 850
short-cut method of Yaws, et al. Used by permission, Yaws, C. L. et Used by permission, Yaws, C. L., et al., Chem. Eng., Jan. 29 (1979), p. 101,
al., Chem. Eng., Jan. 29 (1979), p. 101. all rights reserved.