ดาวน์โหลด All Proceeding - AS Nida

3. Experiments
The objective function was defined by considering the ratio
of the heat duty of the reboiler (Q R1+Q R2) and the specified production
of ethanol (D) [3]. The volume fraction of the ethanol was fixed at 0.95
at top of the rectifying column. The objective function was inserted by
means of the Aspen HYSYS ® .
The procedure starts with the simulation of conventional
distillation column and heat integrated distillation column which uses
data as shown in Table 1 respectively. The total amount of heat rejected
from the mash column (Q R1) and rectifying column (Q R2) will be
compared.
Table 1. Data for simulation conventional and heat integrated
distillation column
Paramters Value
Feed flow rate (F), kmol/h 2335
Number of stages for mash column (N1) 17
Feed stage to mash column (NF1) 6
Number of stages for rectifying column (N2) 25
Feed stage to rectifying column (NF2) 13
Mash feed temperature (TF), o C 30
Volume fraction of ethanol in mash feed (ZF) 0.08
Volume fraction of ethanol in distillate of mash column (XD1) 0.6
Volume fraction of ethanol in distillate of rectifying column (XD2) 0.95
Reflux ratio mash column (R1) 3
Reflux ratio rectifying column (R2) 200
And then the simulation uses to design optimized process for
heat integrated distillation column [4]. A simple procedure is shown in
Fig 4.
1. Conduct the design of the heat integrated distillation column :
determine the number of stages, feed location, feed flow rate, feed
temperature, mole fraction of feed in, output flow rate, mole fraction of
output and reflux ratio.
2. Sensitivity test : evaluate the influence of the main variables and to
decide which variable should be manipulated.
3. Simulate to optimize energy consumption : vary the main variables
which get from sensitivity test as shown in Table.2 (Reflux ratio of
mash column (R 1), volume fraction of ethanol in distillate of mash
column (X D1) and distillate flow rate of rectifying column (D 2)) [5-6].
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4. Compare and conclude for the optimized design – min Q R/D
Conduct the design of the
heat integrated distillation
column
Sensitivity test (R 1, R 2, X D1,
feed stage and D 2)
Simulate to optimize energy
consumption (by vary R 1,
X D1 and D 2)
Compare and conclude for
optimized design
min Q R/D
Obtain the optimization
process
Fig. 4 Procedure for design optimized process
for heat integrated distillation column
QR = QR1 + QR2 5. Obtain the optimization process
(1)
Table 2. Design of experiment to design optimized process for heat
integrated distillation column
Case R1 XD1 D2 (kmol/h)
1 0.5 0.7 60
2 0.5 0.8 60
3 0.5 0.7 70
4 0.5 0.8 70
5 1 0.7 60
6 1 0.8 60
7 1 0.7 70
8 1 0.8 70