October 2006 ROYAL INSTITUTE OF TECHNOLOGY (KTH) INVETIGATIONS OF POTENTIALITIES OF BIOMASS PYROLYSIS AT HTAG SYSTEM SUSPOWER PROJECT UNIVERSITY OF BUCHAREST, FACULTY OF POWER ENGINEERING Author: Cora Gheorghe

1. Objective: the investigation of the biomass behaviour during the pyrolysis process at different temperatures. 2. Parameters considered: the mass losses, the pellet’s temperature. 3. Description of the test facility HTAC experiments were run on a small-scale stand. A scheme of the test facility are show in HTAC experiments were run on a small-scale stand. A scheme of the test facility are show in the next figure: 1 – fuel gas inlet; 2 – mixture of air and nitrogen inlet; 3 – gas burner; 4 – combustion chamber; 5 – honeycomb; 6 – second part of the combustion chamber; 7 – facility’s outlet; 8 – special crew; 9 – small bucket; 10 – nitrogen inlet; 11 – opening glass; 12 – thermocouple which measures the temperature of the fuel gases; 13 – thermocouple which measures the temperature of the flue gases; 14 – gas analysis probe.

4. Feedstock As a feedstock, we used wood pellets, with 10 mm diameter and about 15 mm long. 5. Range of investigations The investigations were carry out for three temperature of the feed gas: 600, 800 and 1000°C and for different pyrolysis times, range from 15 second to 5 minutes. 6. Results 6.1. Mass loss  The figure 1 help to compare the evolution of the mass loss for all three temperatures of the experiments. On the plot, we can observe three steps of the pyrolysis: the first horizontal part of the curve represents the vaporisation of the water; the decreasing continuously, when we have the devolatilisation, witch is faster; the last part of the curve, witch become horizontal, the pyrolysis of the char occurs. From those three curves, an important conclusion results: the temperature accelerates the kinetic of the mass loss. Figure 1 – Evolution of the mass loss versus time for the experiments made

6.2. Temperature of the pellet a) Feed gas temperature = 1000°C b) Feed gas temperature = 800°C c) Feed gas temperature = 600°C 7. Conclusions Figure 2 – Evolution of the pellet temperature function of the time for different temperatures of the feed gas From the figure 2, concerning the temperature of the pellet, higher is the temperature of the feed gas, the temperature of the sample increases. We can observe that the maximum of the pellet’s temperature increases with the increasing of the experiment’s time. It cannot rich the temperature of the feed gas, but it has a close value. The temperature increases very rapidly and it remains Stable for a short time. From the figure 2, concerning the temperature of the pellet, higher is the temperature of the feed gas, the temperature of the sample increases. We can observe that the maximum of the pellet’s temperature increases with the increasing of the experiment’s time. It cannot rich the temperature of the feed gas, but it has a close value. The temperature increases very rapidly and it remains Stable for a short time. Regarding the HITAG experiments for the pyrolysis of the wood pellets it can make the next conclusions. Concerning the mass loss:  the feed gas temperature has a big influence: the temperature accelerates the kinetic of the mass loss;  the vaporisation of the water and the devolatilisation are speed up by the temperature of the feed gas;  the temperature of the feed gas does not influence the char from the pyrolysis. Regarding the HITAG experiments for the pyrolysis of the wood pellets it can make the next conclusions. Concerning the mass loss:  the feed gas temperature has a big influence: the temperature accelerates the kinetic of the mass loss;  the vaporisation of the water and the devolatilisation are speed up by the temperature of the feed gas;  the temperature of the feed gas does not influence the char from the pyrolysis.