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4. Results and discussions
4.1 Simulation of conventional and heat integrated
distillation column
Results of simulation compare between conventional and
heat integrated distillation column (HIDiC) was shown in Table 3 that
HIDiC consumed less energy than conventional. To reach as objective
function the simulation will be based on process parameters and
configuration of heat integrated distillation column.
Table 3. Comparison of specific heat duty between conventional and
heat integrated distillation column
Parameters Conventional HIDiC
Mash feed rate (F), kmol/h 2335 2335
Reflux ratio mash column(R 1) 3 3
Reflux ratio rectifying column(R 2) 200 200
Volume fraction of ethanol in distillate of mash column (XD1) 0.6 0.6
Volume fraction of ethanol in distillate of rectifying column (XD2) 0.95 0.95
Distillate flowrate of rectifying column (D2), kmol/h 70 70
Specific heat duty (QR/D), GJ/mol 1.203 0.974
4.2 Sensitivity Analysis
The objective of this process is to evaluate the influence of
main variables on the energy consumption, to decide which variables
should be optimized [7]. And fig. 5a-e show the effect of reflux ratio of
mash column (R1), reflux ratio of rectifying column (R2), volume
fraction of ethanol in distillate of mash column (XD1), distillate flow rate
of rectifying column (D2) and feed stage of mash column (NF1) on the
specific heat duty while the other parameters are constant. Relationship
of each main parameter and specific heat duty can be described as
below;
• More reflux ratio of mash column (R1), more energy
consumes.
• Vary of rectifying column’s reflux ratio (R2) do not
effect much to total specific heat duty.
• More ethanol composition of distillate of mash
column (XD1), less energy consumes.
• More distillate flow rate of rectifying column (D2), less energy consumes.
• Vary of feed stage of mash column (NF1) do not effect
much to total specific heat duty.
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From the sensitivity analysis it can conclude that only 3
parameters which are 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) effected to energy consumption. To optimize
distillation process only these 3 parameters will be varied and the
design of experiment is shown as table 2.
Fig. 5a Relation between reflux ratio of mash
column and specific heat duty
Fig. 5b Relation between reflux ratio of rectifying
column and specific heat duty
Fig. 5c Relation between ethanol composition of distillate
of mash column and specific heat duty