This paper deals with an investigation into the plate efficiency of a sieve plate tower for stripping chlorine from return brine in soda-chlorine mercury cell process.
Experiments were made, varying the liquid flow rates from 1, 400 to 27, 000kg/m·hr and gas rates from 0.73 to 2.80cm/sec, in the
G/
L range of 0.000170.0025mol/mol.
To find out (
L. T. U.)
ox, the following equation was derived on an assumption that the liquid and the gas come into contact with each other in a cross flow and that the liquid has constant composition in the direction perpendicular to the plate.
xn-1-
xn/
xn-1-
xn+1*=1-exp.{-
lφ/(
L. T. U.)
ox} (12)
As (
L. T. U.)
ox' is independent of the gas rates when the latter is in the neighborhood of 2.8cm/sec, as shown in Fig. 3, it can be concluded that
lA shows the effective travelling length of the liquid and that (
L. T. U.)
ox' is equal to (
L. T. U.)
ox at this gas rate. The values of (
L. T. U.)
ox are plotted against
L' in Fig. 6 and the following correlation is obtained from the line drawn in this figure.
(
L. T. U.)
ox=0.34·
L'
0.6 (21)
As the gas rate is lower than 2.8cm/sec, (
L. T. U.)
ox' is higher than (
L. T. U.)
ox calculated by using Eq. (21). This deviation is due to the more ineffective travelling length of liquid at lower gas rates and is compensated by
F which is defined by means of Eq. (17).
F=
lE/
lA (17)
F=(
L. T. U.)
ox/(
L. T. U.)
ox' (18)
F obtained by using Eq. (20) which has been derived from Eqs. (15), (16) and (17) is represented by the following empirical equations.
F=(0.0011×
L')
-P (19)
P=0.11(
u/
uc-
u)
-1.29 (20)
From these results the author derived the optimum velues of φ and
lA at constant
G/
L which are explained by Eqs. (30) and (31), respectively.
P>0.4: ∂
EML/∂φ>0
P<0.4: ∂
EML/∂φ<0 (30)
For Maximum
EML: d ln
F/
d ln
lA=-1 (31)
Eq. (30) shows that it is recommended to make φ as small as possible in case
P<0.4 (corresponding to
u>0.75cm/sec). Eq. (31) shows the maximum point of
lA-
EML diagram shown in Fig. 8.
lMax can be derived by graphical method as shown in Fig. 9.
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