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SYSTEMATIC DESIGN OF A HEATINTEGRATED REACTIVE DISTILLATION FOR
BIODIESEL PRODUCTION
Lida Simasatitkula, Rafiqul Ganib, Amornchai Arpornwichanopa
a Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University,
Bangkok 10330, Thailandb Chemical & Biochemical Engineering, Technical University of Denmark, Soltofts Plads,
Building 227, DK-2800 Lyngby, Denmark
Contents
Conclusion
Results and discussions : Case study
Methodology
Objective
Introduction
Introduction: Biodiesel
Due to a limited availability of fossil fuels and an increased price of petroleum diesel, biodiesel (a fatty acid alkyl ester) has become an important alternative fuel.
Transesterification reaction
Esterification reaction
2and3 3Triglyceride + CH OH Diglyceride + RCOOCH1k k
3 4and3 3Diglyceride + CH OH Monoglyceride + RCOOCHk k
5 6and3 3Monoglyceride + CH OH Glycerol + RCOOCHk k
3 3 2RCOOH CH OH RCOOCH H O
Introduction: Biodiesel
Reactive distillation can improve the conversion of reversible reactions.
Introduction : Reactive distillation
Advantages of reactive distillation:- Improve process performance- Reduce energy consumption- Improve process economic
Reaction task
Separation task
Separation task
Reactive distillation is considered a process intensification that combine reaction and separation tasks.
Introduction : Heat integrated reactive distillation
• Energy consumption of reactive distillation for heterogeneous catalyzed processes is high.
• A heat-integrated reactive distillation has been proposed with different designs, e.g., a petlyuk reactive distillation, a thermal coupling reactive distillation and an internal heat integrated reactive distillation.
• Caballero and Grossman (2008) proposed a design methodology for the sequence of distillation column and thermally coupling distillation.
Contents
Conclusion
Results and discussions : Case study
Methodology
Objective
Introduction
Objective of this work
• To develop a systematic design of a heat integrated reactive distillation for biodiesel production.
Methyl oleate+methyl linoleate+Glycerol
MethanolL
Water
Water+Glycerol
Crude biodiesel
Waste
Trilinolein
Vapor methanol
Methyl oleate+ methyl
linoleate
Distillated methanol
Water
Contents
Conclusion
Results and discussions : Case study
Methodology
Objective
Introduction
Methodology
Step 1: Define problem
Step 2 : Analyze conventional reactive distillation
Step 3 : Identify heat integrated reactive distillation (generate superstructure)
Step 4 : Screen the number alternatives
Step 5 : Minimize objective function
Step 1: Define problem
-The starting point is problem definition.
- The minimization of a total annual cost is set as a target for process design.
Methodology
Step 1: Define problem
Step 2 : Analyze conventional reactive distillation
Step 3 : Identify heat integrated reactive distillation (generate superstructure)
Step 4 : Screen the number alternatives
Step 5 : Minimize objective function
Step 2.1: Identify limitation of reactive distillation
Step 2.2 : List all component and define product specification
Step 2.3 : rank the boiling point of components
Step 2.4 : Find the component at the top and bottom of column
Step 2.5 : Compute the ratio of properties
Step 2.6 : If the ratio is equal to 1, solvent selection is needed; otherwise skip this step.
Step 2: Analyze a conventional reactive distillation
Methodology
Step 1: Define problem
Step 2 : Analyze conventional reactive distillation
Step 3 : Identify heat integrated reactive distillation (generate superstructure)
Step 4 : Screen the number alternatives
Step 5 : Minimize objective function
Step 3: Identify heat integrated reactive distillation
The objective of this step is to generate a full set of heat integrated reactive distillation columns.
Methodology
Step 4.1: Fast screen the number of alternatives
Step 4.2 : Reduce the number of alternatives from ratio of boiling
point of key components
Step 4.3 : Reduce the number of alternatives from key components
- The lightest key component/light key component- Light key component/heavy key component
Step 4: Screen the number of alternatives
Criteria
Purity of key components
Ratio of boiling point of key component
Type of key components
Methodology
Step 1: Define problem
Step 2 : Analyze conventional reactive distillation
Step 3 : Identify heat integrated reactive distillation (generate superstructure)
Step 4 : Screen the number alternatives
Step 5 : Minimize objective function
Step 5: Minimize objective function
The objective function, a total annual cost, is minimized in order to find a feasible one.
Contents
Conclusion
Results and discussions : Case study
Methodology
Objective
Introduction
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Configuration of a conventional reactive distillation for biodiesel production using heterogeneous acid catalyzed.
Distillated methanol
Methyl oleate+methyl linoleate+Glycerol
Methanol L
Water
Water+Glycerol
Crude biodiesel
Waste
Trilinolein
Vapor methanol
Methyl oleate+ methyl linoleate
Distillated methanol
Water
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Application of the methodology for a heat integrated reactive distillation
Step 1 : Define problem for design of a heat integrated reactive
distillation
Capital costmin Operating cost
3TAC = +
Step 2 : Analyze a conventional reactive distillation
P (atm) Performanceconversion Energy (Btu/h)
Conventional reactive distillation using heterogeneous acid catalyzed
5.5 97.1% 1.78e7
Conventional reactive distillation using alkali catalyzed
1 98.52% 1.0e7
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 2 : Analyze a conventional reactive distillation
Component Ratio of boiling point
Methanol/water 1.45
Water/glycerol 2.85
Glycerol/methyl oleate 1.1
Methyl oleate/oleic acid 1.03
Oleic acid/trilinolein 1.45
It is found that a binary ratio of the boiling point of water and glycerol is the highest value. So water can be separated from glycerol.
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 3 : Identify heat integrated reactive distillation
1. HiRDC without heat exchanger2. HiRDC with heat exchanger3. Petyuk RD 4. Feed split multi-effect RD5. HiRDC with distillation column
without heat exchanger6. HiRDC with distillation column
with heat exchanger7. Thermal coupling indirect RD
integrated with distillation column8. Thermal coupling direct sequence
RD integrated with distillation column
9. Multi-effect indirect split arrangement RD integrated with distillation column.
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 4 : Screen the number of alternatives
1. HiRDC without heat exchanger2. HiRDC with heat exchanger3. Petyuk RD 4. Feed split multi-effect RD5. HiRDC with distillation column
without heat exchanger6. HiRDC with distillation column
with heat exchanger7. Thermal coupling indirect RD
integrated with distillation column8. Thermal coupling direct sequence
RD integrated with distillation column
9. Multi-effect indirect split arrangement RD integrated with distillation column.
3rd criteriaType of key component(water/glycerol)
2nd criteriaRatio of the boiling point is used as criteria.
1st criteriaPurity of water is not mentioned.
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 4 : Screen the number of alternatives
Step 1: Define problem
Step 2 : Analyze conventional reactive distillation
Step 3 : Identify heat integrated reactive distillation (generate superstructure)
Step 4 : Screen the number alternatives
Step 5 : Minimize objective function
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 5 : Minimize objective function
Methanol
Methyl ester+Glycerol
Trilinolein
Waste water
Excess methanol
Boilup
Reflux
Multi-effect indirect split arrangement reactive distillation
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 5 : Minimize objective function
Indirect thermal coupling reactive distillation
Methanol
Methyl ester+Glycerol
Trilinolein
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 5 : Minimize objective function
Heat integrated reactive distillation without heat exchanger (HiRDC without heat exchanger)
Methanol
Methyl ester+Glycerol
Trilinolein Methanol
Waste water
Stripping section Rectifying section
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Step 5 : Minimize objective function
Heat integrated reactive distillation with heat exchanger (HiRDC with heat exchanger)
Methanol
Methyl ester+Glycerol
TrilinoleinMethanol
Methanol+water
Stripping section Rectifying section
Case study : Biodiesel production using heterogeneous catalyst from waste cooking oil
Base case design
multi-effect indirect split arrangement RD
Thermal RD
heat integrated RD without heat exchanger
heat integrated RD with heat exchanger
Pressure of reactive distillation column(bar) 5.5 6 6 6 6Pressure of distillation column 1 1 1 23 23Reaction stage of reactive distillation 11 3 9 8 8Total stage of distillation column for separation water and methanol
9 4 10 10 10
Reboiler duty of reactive distillation (Btu/h) 1.82e7 1.88e7 1.88e7 1.92e7 1.87e7Reboiler duty of distillation for separation methanol from water (Btu/h)
7.98e6 - 1.47e2 - -
Condenser duty of reactive distillation (Btu/h) 7.46e5 - - - -Condense duty of distillation for separation methanol from water (Btu/h)
8.07e6 1e6 8.9e5 1.76e6 8.44e5
TAC of reactive distillation ($/year) 1e6 1.05e6 1.07e6 1.17e6 1.107e6TAC of distillation for separation methanol from water($/year)
5.6e5
Cost saving (%) - 22.35 21.95 17.3 20.17
Contents
Conclusion
Results and discussions
Methodology
Objective
Introduction
Conclusion
• Design methodology for a heat integrated reactive distillation was
proposed.
• The full set of alternatives was generated from a generic superstructure
and the number of alternative is reduced through criteria.
• By performing an economic analysis in terms of total annual cost, a
multi-effect indirect split arrangement reactive distillation is a feasible
one because of the minimum energy consumption and total annual cost.
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