Dipl. Ing. Matthias Mayerhofer Technische Universität München ...

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48 Experiments 12 10 8 6 4 2 0 H_2 0 200 400 600 800 1000 Temperature (°C) Figure 21: Reduction of Nickel based catalyst The reactor was loaded with biomass and it started being heated up at 450°C under N2 flow, while good fluidization of the bed material with steam was achieved. Prior to the catalyst tests the gasifier was operated for ~2 hours to ensure stable operating conditions. In the beginning the product gas bypassed the catalytic test rig and was driven directly in the combustion chamber until steady state gas composition was reached. For the experiments of the iron based catalysts the temperature was raised at 750°C with dp=0.9 mbar and after an hour at these conditions with the gas passing through the catalyst, two tar samples were taken before and after the catalyst test rig. This procedure was repeated for all the different operating conditions that were about to be tested. The set point of dp=0.9 mbar and 800°C was tested twice to compare the tar measurements to the values obtained at the same point about two hours earlier. Finally, the pressure drop reached the lowest point dp=0.45 mbar. The effectiveness of the catalysts was tested in sulfur and chlorine containing environment. The operating conditions at which the samples were taken are presented in the following Table 5. The two additional gas compositions sampling points for the nickel based catalysts were ~12500 1/h for dp=3 mbar and ~14500 1/h for dp=4 mbar. All the calculations were made for 40mL amount of catalyst. However, after the experiments with the iron based catalysts. A protective grid was placed on top of the catalyst amount inside the bed, to prevent the larger particles to be blown away, but for the finer ones it was impossible to avoid it. It is not known if the particles were blown away all at once in the beginning of the experiment or they were linearly decreased. Table 5: Different operating conditions of sampling points for iron based catalysts Sampling Points Temperature (°C) Pressure Drop (mbar) Space Velocity (1/h) 1 750 0,9 6500 2 800 0,9 6500 3 860 0,9 6500 4 800 0,45 4500 5 800 1,5 8500 6 800 2 10000
Experiments 49 6.3.2 Tar Sampling Method-Solid Phase Adsorption (SPA) The correct evaluation of the effectiveness of a catalyst depends strongly on the method that is used for tar sampling. The more accurate the sampling procedure is, the more realistic the results obtained are. Two off line methods are the most commonly used for tar sampling and analysis; the first one is the conventional cold trapping technique in solvent-filled impingers followed by liquid injection. The second one involves the use of multi-bed solid-phase-adsorbent (SPA), in which the gas is adsorbed on the surface of the material and it was initially developed by the Royal Institute of Technology in Sweden. In the present work the SPA method was chosen for tar sampling, instead of the cold trapping technique, due to its numerous advantages. The fact that no solvent is required makes the sampling device very convenient and accurate sampling can be achieved without condensation. So it is simpler in use and maintenance. Also, the detection levels for hydrocarbons are higher, plus it is a time-saving method. Not only the preparation procedure is very short (less than one minute to connect the SPA tube to the sampling line) but also the sampling time is much less (1 sample/min) whereas the other method is time consuming (1 sample/hour) (Dufour,2007). The procedure involves the following steps. A needle is fixed on the tip of a SPA column containing 100 mg of amino phase and a gastight syringe (100mL) is placed to the head of the column. Tar samples were taken by inserting the syringe into the heated lines before and after the catalyst test rig bed via silicon septum. A 100 mL sample was collected in ~1 min as the product gas was in slight overpressure and pushed out the column of the syringe. Then the column was disconnected and covered airtight until the GC-FID analysis. The sample has to be eluted in a solvent prior to its injection in the detector. Dichloromethane was selected by the European Commission joint meeting in Brussels, spring 1998, as the solvent that would be used for all aspects of the method and was adopted as European and US standard (Abatzoglou,2000). The method can be seen in Figure 22 (Ziad Abu El-Rub, 2008). Figure 22: SPA sampling method (Ziad Abu El-Rub 2008)
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Betreuer der Arbeit: Dipl. Ing. Mat
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Acknowledgements This work was acco
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II Content Content Acknowledgements
Page 10 and 11:
IV List of Figures List of Figures
Page 12 and 13:
VI List of Abbreviations List of Ab
Page 14 and 15: VIII Notation Notation ΔH [Kj/mol]
Page 17 and 18: Introduction 1 1 Introduction The d
Page 19 and 20: Introduction 3 1.2 Tasks The presen
Page 21 and 22: Biomass Gasification 5 2 Biomass Ga
Page 23 and 24: Biomass Gasification 7 Spouted Bed
Page 25 and 26: Biomass Gasification 9 2.2 Gas Clea
Page 27 and 28: Biomass Gasification 11 types of ca
Page 29 and 30: Biomass Gasification 13 Mechanical
Page 31 and 32: Biomass Gasification 15 Partial oxi
Page 33 and 34: Biomass Gasification 17 The followi
Page 35 and 36: Biomass Gasification 19 Groups of C
Page 37 and 38: Nickel Based Catalysts 21 even show
Page 39 and 40: Nickel Based Catalysts 23 The conte
Page 41 and 42: Nickel Based Catalysts 25 ing press
Page 43 and 44: Nickel Based Catalysts 27 3.4 Proce
Page 45 and 46: Iron Based Catalysts 29 4 Iron Base
Page 47 and 48: Iron Based Catalysts 31 Measurement
Page 49 and 50: Iron Based Catalysts 33 The percent
Page 51 and 52: Iron Based Catalysts 35 4.6 Catalys
Page 53 and 54: Iron Based Catalysts 37 Reduction i
Page 55 and 56: Iron Based Catalysts 39 and MgO (Di
Page 57 and 58: Precious Metal Catalysts 41 5 Preci
Page 59 and 60: Precious Metal Catalysts 43 Bimetal
Page 61 and 62: Experiments 45 Table 3: Biomass fee
Page 63: Experiments 47 6.3.1Experimental Pr
Page 67 and 68: Results and Discussion 51 7 Results
Page 69 and 70: Results and Discussion 53 7.2 Sampl
Page 71 and 72: Results and Discussion 55 Wet Gas C
Page 73 and 74: Results and Discussion 57 er, the v
Page 75 and 76: Results and Discussion 59 7.3.1. Ef
Page 77 and 78: Results and Discussion 61 The conve
Page 79 and 80: Results and Discussion 63 7.3.3 App
Page 81 and 82: Results and Discussion 65 7.4 Blank
Page 83 and 84: Summary/Outlook 67 The aim is to pr
Page 85 and 86: References 69 (Aznar,1993) Aznar, M
Page 87 and 88: References 71 (Hepola,1997b) Hepola
Page 89 and 90: References 73 (Sarvaramini,2012) Sa
Page 91 and 92: 75 Appendix Appendix A: Iron based
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Dipl. Ing. Matthias Mayerhofer Technische Universität München ...

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