Authors:

1
Dividing Wall Column a New Challenge for
Separation Systems

• Authors
• I. Ivanescu1, D. C. Popescu2,
• C. Dobre2, I. Grozeanu2, R.
  Isopescu3

1 National Oil Corporation PETROM S.A., 109
Cale Victoriei, RO-010069 Bucharest, P.O. BOX
22-109, Romania, Phone [phone], Fax
40-21-3159849, E-mail i.ivanescu_at_petrom.ro 2
National Oil Corporation PETROM S.A., INCERP
Ploiesti Subsidiary, 291A, Republicii Blvd.,
RO-100072 Ploiesti, Romania, Phone
40-244-198738, fax [phone], e-mail
iacob_at_incerp.ro, popescu_at_incerp.ro 3 University
POLITEHNICA of Bucharest, Centre for Technology
Transfer in the Process Industries, 1, Polizu
Street, Building A, Room A056, Sector 1,
RO-011061, Bucharest, Romania, Phone/fax
40-21-2125125 E-mail cttpi_at_chim.upb.ro
2
OUTLINE

• MOTIVATION
• CASE STUDY PRESENTATION
• CASE STUDY RESULTS ANALYSIS
• CONCLUSIONS

3
MOTIVATION

• Over 40 of the energy consumed annually in
  chemical process industries in US is used in
  distillation processes.
• Only in the US there are 40,000 distillation
  columns.
• Distillation accounts for almost 15 of all
  industrial energy consumed in US.
• Worldwide, distillation accounts for 95 of all
  separation
• processes.
• Source Sabarathinam, 2000

Introduction
Introduction
4
INTRODUCTION
5
Conventional arrangements to separate a mixture
of 3 components
Direct sequence
Indirect sequence
6
Thermally coupled arrangements to split 3
components mixture
Petlyuk with prefractionator
Dividing wall column
7
Process integration schemes provide major
challenges in distillation processes in terms of
both capital cost and energy savings.
8
Advantages of dividing wall column arrangement

• improved thermodynamic efficiency by attenuation
  of the mixing effects
• one shell with one reboiler and condenser in
  compact configuration
• about 30 energy savings
• capital cost savings in the same range
• can be applied effectivelly for a variety of
  refinery, gas separation and chemical processes.

9
Dividing Wall Column Short history

• 1949 patent application by O. Wright (USA)
• 1965 first theoretical work by Petlyuk
• 1988 BASF built first dividing wall column
• now BASF operates about 28 dividing wall
  columns
• 2000 largest application (Linde) for Hexane
  plant, Sasol (70m height, 5-6m diameter)

10
CASE STUDY PRESENTATION
LPG production from oil gas
11
Oil gas is appropriate feedstock for LPG
production as it contains large amount of C3 C4
components. The purpose of this study is to
investigate the thermodynamic efficiency of
dividing wall column for LPG production from oil
gas and to compare with with conventional schemes
12
Typical demethanised oil gas stream composition
13
Oil gas feed flow rate 10,000 STD m3/h
14

• Software tools
• COLOM University of Manchester Institute of
  Science and Technology, Department of Process
  Integration
• Based on shortcut model of Triantafyllou
• Used to identify possible sequences of
  distillation column and to optimise design and
  operating parameters
• All the physical property data required are
  imported from HYSYS.Process simulator
• HYSYS.Process ver. 3.2 ASPEN
• Detailed steady-state simulation of previous
  generated arrangements resulted in COLOM
  application software

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CASE STUDY RESULTS ANALYSIS
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RESULTS
LPG composition obtained from simulation (molar
fraction)
17
Condenser and reboiler duties
18
Separation performance
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CONCLUSION
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• The best performance for LPG separation was
  obtained for DWC with 0.9791 C3-C4 molar fraction
• LPG separation from demethanised oil stream in
  DWC involves the lowest duties for condenser and
  reboilers indirect sequence has 9 increase in
  cumulated duty and direct sequence requires 25
  increase in cumulated duty
• According to EN 589 / 2004 specification, motor
  fuel LPG must have at least 89 MON the best
  result is obtained with DWC - 94.09
• Simulation results highlight the great potential
  of DWC for LPG separation compared with
  conventional schemes.

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THANK YOU !