Etude de la combustion de gaz de synthèse issus d'un processus de ...

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Chapter 2 Apart from the described gasifiers, there are several other models that have been developed to improve the quality of the produced gas, such as: twin fluidized bed and entrained bed (Bridgwater, 1995). The first one aims to increase the heat value of the produced gas by promoting the production of H 2 . The second operates at high temperatures 1200 to 1500°C in order to eliminate tar and condensable gases in the produced gas. In fact, it has conversion efficiencies close to 100%. However, some problems arise in the materials selection to withstand the high temperatures and liquefaction of ash. Readers interested in deepening this topic may consult the cited reference. 2.1.3.4 Syngas conditioning tel-00623090, version 1 - 13 Sep 2011 Gases formed by gasification are contaminated by some or all of the constituents listed in Table 2.2. The level of contamination varies, depending on the gasification process and the feedstock. Gas cleaning must be applied to prevent erosion, corrosion and environmental problems in downstream equipment. Table 2.3 also summarizes the main problems resulting from these contaminants, and common cleanup methods. Table 2.2 - Syngas contaminants (Bridgwater, 1995) Contaminant Examples Problems Cleanup method Particulates Ash, char, fluid bed material Erosion Filtration, scrubbing Alkali metals Sodium and potassium Cooling, condensation, Hot corrosion compounds filtration, adsorption Nitrogen Scrubbing, Selective NH 3 e HCN NO x formation components catalytic reduction Clog filters, difficult to Tars Aromatics burn, deposit Tar cracking; Tar removal internally Sulfur, Chloride H 2 S , HCl Corrosion, emissions Lime or dolomite scrubbing or absorption Tars are mostly heavy hydrocarbons (such as pyrene and anthracene) that can clog engine valves, cause deposition on turbine blades or fouling of a turbine system leading to decreased performance and increased maintenance. In addition, these heavy hydrocarbons interfere with synthesis of fuels and chemicals. Conventional scrubbing systems are generally the technology of choice for tar removal from the product syngas. However, scrubbing cools the gas and produces an unwanted waste stream. Removal of the tars by catalytically cracking the larger hydrocarbons reduces 29
Bibliographic revision or eliminates this waste stream, eliminates the cooling inefficiency of scrubbing, and enhances the product gas quality and quantity. 2.2. Syngas applications Applications for syngas can be divided into two main groups: fuels or chemical products and power or heat. Table 2.3 summarizes desirable syngas characteristics for various end-use options. In general, syngas characteristics and conditioning are more critical for fuels and chemical synthesis applications than for hydrogen and fuel gas applications. Table 2.3 – Desirable syngas characteristics for different applications (Ciferno and Marano, 2002) Product Synthetic fuels Methanol Hydrogen Boiler Fuel gas Turbine tel-00623090, version 1 - 13 Sep 2011 H 2 /CO 0.6 (a) ~2.0 High Unimportant Unimportant CO 2 Low Low (c) Unimportant (b) Not critical Not critical Hydrocarbons Low (d) Low (d) Low (d) High High N 2 Low Low Low (e) (e) H 2 O Low Low High (f) Low (g)
Page 1 and 2: THÈSE Pour l’obtention du Grade
Page 3 and 4: Acknowledgements Acknowledgements T
Page 5 and 6: Résumé __________________________
Page 7 and 8: Nomenclature Nomenclature Roman tel
Page 9 and 10: Nomenclature Subscripts tel-0062309
Page 11 and 12: Contents tel-00623090, version 1 -
Page 13 and 14: Contents 6.4. SYNGAS FUELLED-ENGINE
Page 15 and 16: Introduction CHAPTER 1 INTRODUCTION
Page 17 and 18: Introduction proves to have higher
Page 19 and 20: Introduction Chapter 3 - Experiment
Page 21 and 22: Bibliographic revision CHAPTER 2 BI
Page 23 and 24: Bibliographic revision point today
Page 25 and 26: Bibliographic revision - Boudouard
Page 27 and 28: Bibliographic revision Table 2.1 -
Page 29 and 30: Bibliographic revision Biomass Dryi
Page 31: Bibliographic revision Circulating
Page 35 and 36: Bibliographic revision established
Page 37 and 38: Bibliographic revision Hydrogen Hyd
Page 39 and 40: Bibliographic revision of low moist
Page 41 and 42: Bibliographic revision scrubbing an
Page 43 and 44: Bibliographic revision suggests tha
Page 45 and 46: Bibliographic revision 1 d( δ A) 1
Page 47 and 48: Bibliographic revision Since n is
Page 49 and 50: Bibliographic revision 2 ( rsr ) 2
Page 51 and 52: Bibliographic revision This evoluti
Page 53 and 54: Bibliographic revision The burning
Page 55 and 56: Bibliographic revision δVG = − a
Page 57 and 58: Bibliographic revision 2 1 − −
Page 59 and 60: Bibliographic revision where the su
Page 61 and 62: Bibliographic revision the stretche
Page 63 and 64: Bibliographic revision burning velo
Page 65 and 66: Experimental set ups and diagnostic
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Experimental set ups and diagnostic
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Chapter 4 CHAPTER 4 EXPERIMENTAL AN
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Chapter 4 4.1 Laminar burning veloc
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Chapter 4 4.1.1.1 Flame morphology
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Chapter 4 P i = 1.0 bar, Ti = 293 K
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Chapter 4 Figure 4.5 shows schliere
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Chapter 4 P i = 2.0 bar, T i = 293
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Chapter 4 Sn (m/s) 3.0 2.5 2.0 1.5
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Chapter 4 5 ms 10 ms 15 ms 20 ms 25
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Chapter 4 behaviour of the curves r
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Chapter 4 1.50 Sn (m/s) 1.25 1.00 0
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Chapter 4 0.5 0.4 φ =1.0 Su (m/s)
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Chapter 4 variation of the normaliz
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Chapter 4 4.1.1.6 Comparison with o
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Chapter 4 The values of laminar bur
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Chapter 4 Pressure (bar) 7 6 5 4 3
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Chapter 4 0.5 0.4 φ=1.2 Su (m/s) 0
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Chapter 4 0.3 φ=0.8 Su (m/s) 0.2 0
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Chapter 4 a minimum pressure to exp
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Chapter 4 Notice the similar behavi
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Chapter 4 A very good agreement bet
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Chapter 4 ( ) Q = h T − T (4.21)
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Chapter 4 tel-00623090, version 1 -
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Chapter 4 are tested and discussed.
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Chapter 4 7 500 Pressure (bar) 6 5
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Chapter 4 Pressure (bar) 7 6 5 4 3
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Chapter 4 4.2.3.4 Quenching distanc
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Chapter 4 10000 Quenching distance
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Chapter 5 CHAPTER 5 EXPERIMENTAL ST
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Chapter 5 30 10 25 8 Pressure (bar)
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Chapter 5 30 Piston position (mm) 2
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Chapter 5 5.1.1.4 In-cylinder press
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Chapter 5 estimation of various par
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Chapter 5 TDC 1.25 ms 2.5 ms 3.75 m
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Chapter 5 Piston position (mm) 500
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Chapter 5 From figure 5.15 is possi
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Chapter 5 From figure 5.16 is obser
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Chapter 5 80 Pressure (bar) 70 60 5
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Chapter 5 80 10 Pmax (bar) 70 60 50
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Chapter 5 -5.0 ms -3.75 ms -2.5 ms
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Chapter 5 observation emphasis the
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Chapter 6 CHAPTER 6 NUMERICAL SIMUL
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Chapter 6 centered at the spark plu
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Chapter 6 H 2 O, (3) N 2 , (4) O 2
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Chapter 6 For all the above express
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Chapter 6 motions within the cylind
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Chapter 6 Heat transfer Wei et al.,
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Chapter 6 The calibration coefficie
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Chapter 6 6.3.2.2 In-cylinder volum
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Chapter 6 40 Experimental 30 Numeri
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Chapter 6 80 70 60 Numerical Experi
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Chapter 6 downdraft syngas than for
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Chapter 6 80 23º BTDC 60 29.5º BT
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Chapter 6 with experimental results
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Conclusions CHAPTER 7 CONCLUSIONS 7
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Conclusions radius and time for syn
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Conclusions conditions, therefore s
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Conclusions tel-00623090, version 1
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References References tel-00623090,
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References tel-00623090, version 1
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Appendix A - Overdetermined linear
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Appendix A - Overdetermined linear
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Appendix B- Syngas-air mixtures pro
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Appendix C -Rivère model Heat flux
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Appendix C -Rivère model The work
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tel-00623090, version 1 - 13 Sep 20
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