24/03/2014 Torrefaction R&D Contents Introduction Problem definition Proposed Solution Results Z.C. Bourgonje Promotors: Prof. H.J. Veringa Prof. D.M.J. Smeulders Department of mechanical engineering 2-4-2014 Introduction - Biolake system Water vapor Low temperature dryer @60-100°C Untreated biomass High temperature dryer @110-160°C heat Chipper natural gas (only needed for start ing up) Syn gas air burner Cooling screw @50 °C Torrefied pelletised biomass Torrefaction unit @260-350 °C Pelletizer Boundary BioLake system Water reservoir general BioLake pellet production schematic 2 1 24/03/2014 Problem definition - Torrefaction process stages Source: ECN 3 Problem definition 2 - Energy balance The heating value of syngas at a certain temperature/residence time 10.000 9.000 Scenario 1 Scenario 2 8.000 Scenario 6 LHV [MJ/kg gas] 7.000 6.000 5.000 4.000 3.000 2.000 1.000 0.000 200 210 220 230 240 250 260 270 280 290 Temperature [°C] Source: M.J.C. van der Stelt 2 24/03/2014 p.s. - Experimental setup- overview p.s. Experimental setup – torrefaction reactor Argon inlet (hot) Argon/air inlet (Cold) 3 24/03/2014 Experimental setup – Catalytic combustion of syngas Air inlet oven Thermocouples catalyst p.s. Experimental setup – heat exchanger Ambient T4 T3 Thermo-electric element T1 T2 Gas flow in Gas flow out Thermocouple 4 24/03/2014 Large particle torrefaction Fast heat transfer vs. slow reactivity Time Slow heat transfer vs. fast reactivity Time Torrefied biomass Rate of torrefaction Fresh biomass Large particle torrefaction beech ø28mm, 200mm oven temperature setting 250C, residence 60 min 168°C 60min 198°C 60min 226°C 60min 248°C 60min 267°C 60min 290°C 60min oven temperature 350, residence time 10 min Cross section over the length Tmax 214°C Tmax 239°C Tmax 247°C Tmax 288°C Tmax 288°C Tmax 325°C Outside 5 24/03/2014 Large particle torrefaction 20mm @ 250°C quartz reactor 350 beechwood ø20mm,L=30mm @250°C for 30min 300 Temperature [°C] 250 200 150 100 center 3mm from center 6mm from center 50 0 time[hour:min] Combusting the syngas 6 24/03/2014 Controlling the torrefaction process with air Calibration of the heat exchanger Electrical energy supplied to the peltier element as function of the thermal energy of incoming gas 2,5 P thermoelectric [W] 2 1,5 1 0,5 0 0,00 2,07 4,14 6,22 8,29 10,36 12,43 14,50 16,58 Qair [W] What to do next: 1. Better insulation of the heat exchanger and tubes 2. Build a PID controller for the thermoelectric element 3. Build a new reactor with a smaller diameter & wall thickness 7 24/03/2014 Questions? 15 8
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