Lida Simasatitkul a, Rafiqul Gani b, Amornchai Arpornwichanop a a Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand b Chemical & Biochemical Engineering, Technical University of Denmark, Soltofts Plads, Building 227, DK-2800 Lyngby, Denmark

Conclusion Results and discussions : Case study Methodology Objective Introduction

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 Reactive distillation can improve the conversion of reversible reactions.

Advantages of reactive distillation: - Improve process performance - Reduce energy consumption - Improve process economic Reaction task Separation task Reactive distillation is considered a process intensification that combine reaction and separation tasks.

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.

Conclusion Results and discussions : Case study Methodology Objective Introduction

To develop a systematic design of a heat integrated reactive distillation for biodiesel production.

Conclusion Results and discussions : Case study Methodology Objective Introduction

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.

Step 2: Analyze a conventional reactive distillation

Step 3: Identify heat integrated reactive distillation The objective of this step is to generate a full set of heat integrated reactive distillation columns.

Step 4: Screen the number of alternatives Criteria Purity of key components Ratio of boiling point of key component Type of key components

Step 5: Minimize objective function The objective function, a total annual cost, is minimized in order to find a feasible one.

Conclusion Results and discussions : Case study Methodology Objective Introduction

Configuration of a conventional reactive distillation for biodiesel production using heterogeneous acid catalyzed.

Application of the methodology for a heat integrated reactive distillation Step 1 : Define problem for design of a heat integrated reactive distillation Step 2 : Analyze a conventional reactive distillation P (atm)Performance conversionEnergy (Btu/h) Conventional reactive distillation using heterogeneous acid catalyzed %1.78e7 Conventional reactive distillation using alkali catalyzed %1.0e7

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.

Step 3 : Identify heat integrated reactive distillation 1.HiRDC without heat exchanger 2.HiRDC with heat exchanger 3.Petyuk RD 4.Feed split multi-effect RD 5.HiRDC with distillation column without heat exchanger 6.HiRDC with distillation column with heat exchanger 7.Thermal coupling indirect RD integrated with distillation column 8.Thermal coupling direct sequence RD integrated with distillation column 9.Multi-effect indirect split arrangement RD integrated with distillation column.

Step 4 : Screen the number of alternatives 1.HiRDC without heat exchanger 2.HiRDC with heat exchanger 3.Petyuk RD 4.Feed split multi-effect RD 5.HiRDC with distillation column without heat exchanger 6.HiRDC with distillation column with heat exchanger 7.Thermal coupling indirect RD integrated with distillation column 8.Thermal coupling direct sequence RD integrated with distillation column 9.Multi-effect indirect split arrangement RD integrated with distillation column. 3 rd criteria Type of key component (water/glycerol) 2 nd criteria Ratio of the boiling point is used as criteria. 1 st criteria Purity of water is not mentioned.

Step 4 : Screen the number of alternatives

Step 5 : Minimize objective function Multi-effect indirect split arrangement reactive distillation

Step 5 : Minimize objective function Indirect thermal coupling reactive distillation

Step 5 : Minimize objective function Heat integrated reactive distillation without heat exchanger (HiRDC without heat exchanger) Stripping sectionRectifying section

Step 5 : Minimize objective function Heat integrated reactive distillation with heat exchanger (HiRDC with heat exchanger) Stripping section Rectifying section

Base case design multi-effect indirect split arrangeme nt RD Thermal RD heat integrated RD without heat exchanger heat integrated RD with heat exchanger Pressure of reactive distillation column(bar) Pressure of distillation column Reaction stage of reactive distillation Total stage of distillation column for separation water and methanol Reboiler duty of reactive distillation (Btu/h)1.82e7 1.88e7 1.92e71.87e7 Reboiler duty of distillation for separation methanol from water (Btu/h) 7.98e e2-- Condenser duty of reactive distillation (Btu/h) 7.46e Condense duty of distillation for separation methanol from water (Btu/h) 8.07e6 1e68.9e51.76e68.44e5 TAC of reactive distillation ($/year) 1e61.05e6 1.07e61.17e61.107e6 TAC of distillation for separation methanol from water($/year) 5.6e5 Cost saving (%)

Conclusion Results and discussions Methodology Objective Introduction

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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