NUMERICAL APPROACH TO WOOD PYROLYSIS IN CONSIDERATION HEAT AND MASS TRANSFER AND CHEMICAL REACTION

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1 NUMERICAL APPROACH TO WOOD PYROLYSIS IN CONSIDERATION HEAT AND MASS TRANSFER AND CHEMICAL REACTION THESIS MUHAMMAD IDRIS / TM ENGINEERING FACULTY UNIVERSITAS SUMATERA UTARA M E D A N 2014

2 NUMERICAL APPROACH TO WOOD PYROLYSIS IN CONSIDERATION HEAT AND MASS TRANSFER AND CHEMICAL REACTION THESIS Untuk Memperoleh Gelar Magister Teknik Dalam Program Studi Magister Teknik Mesin Pada Fakultas Teknik OLEH MUHAMMAD IDRIS / TM FAKULTAS TEKNIK UNIVERSITAS SUMATERA UTARA MEDAN 2014

3 LEMBARAN PENGESAHAN Judul Penelitian : NUMERICAL APPROACH TO WOOD PYROLYSIS IN CONSIDERATION HEAT AND MASS TRANSFER AND CHEMICAL REACTION Nama Mahasiswa : MUHAMMAD IDRIS Nomor Pokok : Program Studi : MAGISTER TEKNIK MESIN Menyetujui : Komisi Pembimbing Prof. Hiroomi Homma ( Ketua ) Dr. Eng. Himsar Ambarita, ST, MT ( Anggota ) Ketua Program Studi Dekan Fakultas Teknik Dr. Eng. Ir. Indra, MT Prof. Dr. Ir. Bustami Syam, MSME

4 Tanggal Lulus : 07 Juni 2014

5 Telah diuji pada Tanggal : PANITIA PENGUJI TESIS Ketua Anggota : Prof. Dr. Ir. Farel H. Napitupulu, DEA : 1. Dr. Eng. Himsar Ambarita, ST, MT 2. Prof. Farel. H. Napitupulu, DEA 3. Prof. Dr. Ir. Ilmi Abdullah, M.Sc 3. Dr. Eng. Ir. Taslim, MT

6 ABSTRACK Climate change, global warming, and energy crisis are critical issues to be solved urgently in a global framework. Alternative energy and renewable energy technologies must be quickly developed to be substituted for fossil fuels like oil, gases, and coal. USA, UE, and Japan invested huge budgets to develop biomass renewable energy technology. Their target is to develop commercial base large-scaled plant. On the other hand, in developing countries, especially in rural areas, people who can access electricity is still less than 70%, To decelerate or prevent global warming, and improve electrification in rural areas, a new technology for wood pyrolysis, which requires low manufacturing cost and less maintenance, and of which gases are directly applicable to gas engine generator, was developed by the previous work. This work aims at understanding pyrolysis process in the pre-vacuum chamber in more detail and thus improving the plant performance, and carries out numerical analysis on the pyrolysis process taking into account fluid dynamics and chemical reaction inside the pre-vacuum chamber. The numerical results provide useful information to understand the pyrolysis process and to improve the plant performance. Keywords: pyrolysis, pre-vacuum chamber, chemical reaction, volatile sublimation, ANSYS Fluent

7 ABSTRAK Perubahan iklim, pemanasan global, dan krisis energi merupakan masalah yang sangat mendesak untuk segera diselesaikan dalam global framework. Teknologi energi terbarukan dan energi alternatif ini harus segera dikembangkan untuk menggantikan bahan bakar fosil seperti minyak, gas, dan batu bara. USA, UE, dan Jepang telah meninvestasikan anggaran dalam jumlah yang sangat besar untuk mengembangkan teknologi energi terbarukan biomassa. Target mereka adalah untuk mengembangkan basis pabrik komersial dalam skala besar. Di sisi lain, di negara berkembang, terutama di daerah pedesaan, masalah yang dialami oleh masyarakat adalah akses listrik masih kurang dari 70 persen, oleh karena itu untuk memperlambat atau mencegah pemanasan global, dan meningkatkan elektrifikasi di wilayah pedesaan, sebuah teknologi baru untuk pirolisis kayu, dengan biaya dan teknologi yang rendah, sedikit biaya perawatan, dan gas yang diperoleh secara langsung bisa diterapkan pada mesin generator berbahan bakar gas, dimana telah dikembangkan oleh pekerjaan sebelumnya. Penelitian ini bertujuan untuk memahami proses pirolisis di dalam pre-vacuum chamber secara lebih rinci, meningkatkan kinerja peralatan, dan melakukan analisis numerik pada proses pirolisis dengan mempertimbangkan dinamika fluida dan reaksi kimia di dalam pre-vacuum chamber. Hasil numerik memberikan informasi yang berguna untuk memahami proses pirolisis dan untuk meningkatkan kinerja perlatan. Kata kunci: pyrolysis, pre-vacuum chamber, chemical reaction, volatile sublimation, ANSYS Fluent

8 DAFTAR ISI Halaman ABSTRACT. ABSTRAK.... ACKNOWLEDGMENT.. CURRICULUM VITAE..... CONTENTS..... TABLE CONTENTS.... FIGURE CONTENTS... NOTATION CONTENTS i ii iii v viii xi xii xiv 1 INTRODUCTION Background Global Warming Energy Crisis Indonesia Energy Conditions Renewable Energy Status in Indonesia Biomass Potential in Indonesia Limitation of Problem Research Objective REVIEW OF LITERATURE Reviews on Previous Woods Pyrolysis Researches Biomass Conversion Processes Thermochemical Reactions in Wood Pyrolysis Experimental Works of Wood Pyrolysis Kinetic Models in Biomass Pyrolysis Numerical Analysis of pyrolysis Governing Equations in CDF Assumptions of Numerical Analysis EXPERIMENTAL WORK... 33

9 3.1. Place and Time Material and Method Used for Experiment Feedstock of Pyrolysis Experimental Equipment Temperature Measurement Experimental Method Measured Results Temperature Pressure Pyrolysis Yield Conclusions NUMERICAL ANALYSIS ON THERMAL CONDUCTION IN PRE- VACUUM CHAMBER Introduction Numerical Analysis Method Thermal Conduction Model Heating Condition of Wood Stove Furnace Model of Feedstock Charge Mesh Model Numerical Result and Discussion Synoptic View of Temperature Comparison between Numerical and Experimental Results inside Chamber Temperature Distribution inside Chamber Temperature Distribution at 400 Seconds Temperature Distribution at 800 Seconds Temperature Distribution at 1200 Seconds Conclusions NUMERICAL ANALYSIS ON WOOD PYROLYSIS IN PRE- VACUUM CHAMBER Introduction Modelling of Pre-Vacuum Chamber Pyrolysis Mesh model of Pre-Vacuum Chamber Boundary Conditions of Pre-Vacuum Chamber Fluent Solution Options Chemical kinetics Chemical Formula and Reaction Volatilization Endothermic Reaction... 71

10 5.3. Numerical Results Pressure Evolution with Time Temperature in Pre-Vacuum Chamber Decomposition of Volatile Gas Discussion Volatile Sublimation Comparison of Numerical Analysis Results by Thermal Conduction and Heat Mass Transfer Analysis Conclusions SUMMARY AND RECOMMENDATION Summary Recommendation BIBLIOGRAPHY APPENDIX... 91

11 TABLE CONTENTS Number Title Page 1.1. Renewable Energy Potential in Indonesia Energy Potential of Biomass by Region in Indonesia Typical Proximate and Ultimate Analyses of Dry Wood by Weight (%) Pyrolysis Yield Material Model Material properties used for numerical analysis Arrhenius type of chemical kinetics parameters Calculation of volatile elements... 69

12 FIGURE CONTENTS Number Title Page 1.1. Worlds Energy Consumption Energy consumption per capita (1990, 2000, 2010 and 2030) World Oil Production The Energy Consumption in by Type Projection of total final energy demand by energy sector Current Energy Mix versus Future Energy Goals Chart of the Biomass Conversion Process The process of gasification and pyrolysis Thermal stability main components of wood Stage Process Of Thermal Decompose Wood Component Illustration of a pyrolysis pilot plant for this study Additional devices Temperature measurement Temperature as a function of time Chamber pressure as a function of time Chamber model ANSYS Analysis Model Heating function Meshing model Temperature contour at 1200 second (20 minutes) Temperature (T1) at the chamber bottom... 49

13 4.7. Comparison between temperatures (T2) near the chamber top Temperature at flange top surface Temperature distribution at 400 second Temperature distributions at 800 seconds Temperature distribution at 1200 second Fluent analysis model Boundary Condition of Pre-Vacuum Chamber Pyrolysis kinetics used for this numerical analysis Pressure evolution with time in pre-vacuum chamber Time evolution of volume-average temperaturein Mole Concentration of each Species as a function of time Comparison of Numerical Analysis Results by Thermal Conduction and Heat Mass Transfer Analysis... 79