NUMERICAL APPROACH TO WOOD PYROLYSIS IN
CONSIDERATION HEAT AND MASS TRANSFER
AND CHEMICAL REACTION
THESIS
MUHAMMAD IDRIS 117015011/ TM
ENGINEERING FACULTY
UNIVERSITAS SUMATERA UTARA
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 Universitas Sumatera Utara
OLEH
MUHAMMAD IDRIS 117015011/ TM
FAKULTAS TEKNIK
UNIVERSITAS SUMATERA UTARA
MEDAN
LEMBARAN PENGESAHAN
Judul Penelitian : NUMERICAL APPROACH TO WOOD PYROLYSIS IN CONSIDERATION HEAT AND MASS TRANSFER AND CHEMICAL REACTION
Nama Mahasiswa : MUHAMMAD IDRIS Nomor Pokok : 117015011
Program Studi : MAGISTER TEKNIK MESIN
Menyetujui : Komisi Pembimbing
( Ketua )
Prof. Hiroomi Homma
( Anggota )
Dr. Eng. Himsar Ambarita, ST, MT
Ketua Program Studi
Dr. Eng. Ir. Indra, MT
Dekan Fakultas Teknik
Telah diuji pada
Tanggal :
PANITIA PENGUJI TESIS
Ketua : Prof. Dr. Ir. Farel H. Napitupulu, DEA
Anggota : 1. Dr. Eng. Himsar Ambarita, ST, MT
2. Prof. Farel. H. Napitupulu, DEA
3. Prof. Dr. Ir. Ilmi Abdullah, M.Sc
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.
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.
DAFTAR ISI
Halaman
ABSTRACT ……….……… i
ABSTRAK ..……….. ii
ACKNOWLEDGMENT ………..……… iii
CURRICULUM VITAE ...……….. v
CONTENTS ..………..………. viii
TABLE CONTENTS ………..……….. xi
FIGURE CONTENTS………..………. xii
NOTATION CONTENTS ……… xiv
1 INTRODUCTION ...………..………. 1
1.1. Background ...………. 1
1.1.1. Global Warming ... 2
1.1.2. Energy Crisis ... 4
1.1.3. Indonesia Energy Conditions ... 7
1.1.4. Renewable Energy Status in Indonesia ... 9
1.1.5. Biomass Potential in Indonesia ... 12
1.2. Limitation of Problem ………...………. 15
1.3. Research Objective .…….……….. 15
2 REVIEW OF LITERATURE ..………...………... 17
2.1. Reviews on Previous Woods Pyrolysis Researches ..…….……… 17
2.1.1. Biomass Conversion Processes... 17
2.1.2. Thermochemical Reactions in Wood Pyrolysis ... 20
2.1.3. Experimental Works of Wood Pyrolysis ... 23
2.1.4. Kinetic Models in Biomass Pyrolysis ... 24
2.1.5. Numerical Analysis of pyrolysis ... 28
2.1.5.1. Governing Equations in CDF ... 29
2.1.5.2. Assumptions of Numerical Analysis ... 31
3.1. Place and Time ... 33
3.2. Material and Method Used for Experiment ... 33
3.2.1. Feedstock of Pyrolysis ... 33
3.2.2. Experimental Equipment ... 34
3.2.3. Temperature Measurement ... 35
3.2.4. Experimental Method ... 36
4 NUMERICAL ANALYSIS ON THERMAL CONDUCTION IN PRE-VACUUM CHAMBER ... 42
4.1. Introduction ... 42
4.2. Numerical Analysis Method ... 42
4.2.1. Thermal Conduction Model ... 42
4.2.2. Heating Condition of Wood Stove Furnace ... 45
4.2.3. Model of Feedstock Charge ... 46
4.2.4. Mesh Model ... 47
4.3. Numerical Result and Discussion ... 47
4.3.1. Synoptic View of Temperature ... 47
4.3.2. Comparison between Numerical and Experimental Results inside Chamber ... 49
4.3.3. Temperature Distribution inside Chamber... 52
4.3.4. Temperature Distribution at 400 Seconds ... 52
4.3.5. Temperature Distribution at 800 Seconds ... 53
4.3.6. Temperature Distribution at 1200 Seconds ... 54
4.4. Conclusions ... 56
5 NUMERICAL ANALYSIS ON WOOD PYROLYSIS IN PRE-VACUUM CHAMBER ... 57
5.1. Introduction ... 57
5.2. Modelling of Pre-Vacuum Chamber Pyrolysis ... 60
5.2.1. Mesh model of Pre-Vacuum Chamber ... 60
5.2.1.1. Boundary Conditions of Pre-Vacuum Chamber ... 62
5.2.1.2. Fluent Solution Options ... 63
5.2.2. Chemical kinetics ... 65
5.2.3. Chemical Formula and Reaction ... 67
5.2.4. Volatilization ... 70
5.3. Numerical Results ... 72
5.3.1. Pressure Evolution with Time ... 73
5.3.2. Temperature in Pre-Vacuum Chamber ... 74
5.3.3. Decomposition of Volatile Gas ... 75
5.4. Discussion ... 77
5.4.1. Volatile Sublimation ... 77
5.4.2. Comparison of Numerical Analysis Results by Thermal Conduction and Heat Mass Transfer Analysis ... 77
5.5. Conclusions ... 79
6 SUMMARY AND RECOMMENDATION ... 82
6.1. Summary ... 82
6.2. Recommendation ... 84
BIBLIOGRAPHY ... 86
TABLE CONTENTS
Number Title Page
1.1. Renewable Energy Potential in Indonesia ... 12
1.2. Energy Potential of Biomass by Region in Indonesia ... 13
2.1. Typical Proximate and Ultimate Analyses of Dry Wood by
Weight (%) ... 24
3.1. Pyrolysis Yield ... 40
4.1. Material Model
...
45
5.1. Material properties used for numerical analysis ... 61
5.2. Arrhenius type of chemical kinetics parameters ... 67
5.3. Calculation of volatile elements
...
FIGURE CONTENTS
Number Title Page
1.1. Worlds Energy Consumption ... 5
1.2. Energy consumption per capita (1990, 2000, 2010 and 2030) ... 5
1.3. World Oil Production ... 6
1.4. The Energy Consumption in 2000 - 2010 by Type ... 8
1.5. Projection of total final energy demand by energy sector ... 9
1.6. Current Energy Mix versus Future Energy Goals ... 10
2.1. Chart of the Biomass Conversion Process ... 17
2.2. The process of gasification and pyrolysis ... 20
2.3. Thermal stability main components of wood ... 21
2.4. Stage Process Of Thermal Decompose Wood Component ... 22
3.1. Illustration of a pyrolysis pilot plant for this study ... 34
3.2. Additional devices ... 35
3.3. Temperature measurement ... 36
3.4. Temperature as a function of time ... 38
4.5. Temperature contour at 1200 second (20 minutes) ... 48
4.7. Comparison between temperatures (T2) near the
chamber top ... 50
4.8. Temperature at flange top surface ... 51
4.9. Temperature distribution at 400 second ... 53
4.10. Temperature distributions at 800 seconds ... 54
4.11. Temperature distribution at 1200 second ... 55
5.1. Fluent analysis model ... 61
5.2. Boundary Condition of Pre-Vacuum Chamber ... 63
5.3. Pyrolysis kinetics used for this numerical analysis ... 67
5.4. Pressure evolution with time in pre-vacuum chamber ... 73
5.5. Time evolution of volume-average temperaturein ... 75
5.6. Mole Concentration of each Species as a function of time ... 76
