Evaluation of Heat-integrated Distillation Schemes
Transcript of Evaluation of Heat-integrated Distillation Schemes
Evaluation of Heat‐integrated Distillation Schemes
Mansour EmtirLibyan Petroleum Institute, P.O. Box 6431 Tripoli, Libya
EMINENT2 Workshop, 5 - 6 May 2008, Veszprem, Hungary
Outlines
• Background
• Objectives
• Studied distillation schemes
• Case study
• Optimization procedure
• Results & discussion
• Conclusions
2
Background
Distillation is used for (~90%) of all fluid separation in the chemical industry
Distillation is an energy consuming process, it consumes ~13% of the energy needed by the whole chemical industry
Tighter environmental regulations, higher energy costs and growing competition have increased the demand for more efficient distillation system
3
Objectives
4
Examine different heat integration modes for the separation of ternary mixture
Comparison based on shortcut method, pinch analysis and rigorous simulation
Evaluate the effect of feed conditions on heat integration
Studied distillation schemes
Direct sequence (D) base case
Indirect sequence (I)
5
Studied distillation schemes (Cont.)
P1 > P2 P2 > P1
6
Forward heat integration,direct sequence (DQF)
Backward heat integration,direct sequence (DQB)
Studied distillation schemes (Cont.)
7
Col.1 Col.2ABC
A
B
C
V21
L21
L 12
S
Q
B
L D
V
R=L/ D
SR
BR=V/ B
V12
Petlyuk column (SP)
Studied distillation schemes (Cont.)
P1 > P2 P2 > P1
8
Sloppy sequence, forward heat integration (SQF)
Sloppy sequence, backward heat integration (SQB)
Case study
The feed is ternary mixture of (Benzene, Toluene, m‐ xylene)
Feed Composition (0.25/0.50/0.25) Feed Pressure = 101.33 KpaFeed flow rate = 100 kmol/hFeed conditions:
Liquid at 20 °CSaturated liquid Saturated vapor
Products Purity = 99.9 mol %
9
Optimization procedure
10
Pressure
Numberof trays
Feedlocation
Checkopti‐malityandspecs
Pressure
Numberof trays
Drawlocation
Feedlocation
Recyclesflow
Column (1) Column (2)
Checkopti‐
malityand
specs
TAC
Design
TAC
Comparingscenarios
HYSYS EXCEL
11
Case Study
Rigorous Simulation Shortcut Analysis
FORTRAN Program
Shortcut Results (Rmin, Nmin )
Pinch Analysis
Shortcut Equations (FUG)
HYSYS Simulation CPI Software (Sprint)
Composite Curve Analysis
Pinch Analysis Results
Simulation Results
Energy & TAC Saving
Optimal solution DataData
12
HYSYS PFD for DQB distillation scheme
Results and discussion
13
4445
4647
484928 29 30 31 32
1.090
1.092
1.094
1.096
1.098
1.100
1.102
1.104
1.107
1.109
1.111
1.113
1.115
1.117
1.119
Total annual cost (MM$/year)
Trays of Column 1
Trays of Column 2
3D‐ view for optimization of DQB scheme
Composite curve of base case (D)
14
Composite curve of DQB scheme
15
16
Energy & TAC saving compared to base case (D), liquid state
Energy & TAC saving % of DQB, different feed conditions
17
Energy & TAC saving % of Petlyuk column, different feed conditions
18
Heat‐integrated distillation schemes offers an alternative toconventional distillation schemes, with the possibility of savings inboth energy and capital costs
The state of feed conditions plays important role on the optimizationranking of distillation schemes
DQB & SQD schemes are showing higher energy saving for feedentering at liquid state, this due to the recycling of the energy utilizedto change the phase of the feed inside the integrated system
Petlyuk column is more effecient when supplying the feed atsaturated liquid phase
Conclusions
19
THANK YOU ALL