Xiyan Li

During the stay at Bioenergy 2020+, I used a Fixed-bed lab scale reactor (Rig code BE3) to perform my experiments. There were two purposes of this visit. The first one was to perform a smoldering combustion/pyrolysis experiment by using the fixed-bed lab scale reactor. The primary flow was set to 30L/min air to get smoldering combustion. To achieve this, the sample holder in this test rig was prolonged to 174mm, so that the decomposition region was extended. A CFD model was built to simulate the fixed bed smoldering combustion and pyrolysis. The same sample holder was also applied on pyrolysis experiments as a trial. The pyrolysis under N2 were tried using 30L/min and 5L/min. The results for pyrolysis were not satisfying; therefore the pyrolysis experiments were cancelled after these initial trials. The experimental data will be compared with the simulation data after the visit, and a journal paper is prepared based on the simulation and experiment.  

The second purpose of this visit was to look into the impact factor during biomass fixed bed combustion. In order to achieve this, a minimum fluidized velocity inside the bed was calculated. After that, a range of primary air velocities was investigated. The idea was to change the velocity of primary air flow and observe the temperature changes inside the bed and the amount of different gases during the reaction. By analyzing these data, we could observe different reaction mechanisms, for example, O2 limited, O2 sufficient, convection-controlled, and so on. The expected phenomena are O2 limited: volatile combustion front moves from top to bottom whereas char combustion front moves from bottom to top. O2 sufficient: both the volatile combustion front and char combustion front move from top to bottom. In the real experiment, we replicated this process and we have relatively good results.  

In order to give a complete picture to those two purposes, a series of other experiments are also needed. The table below shows all the experiments that the host could support. The experiments that we tried and the status are also included.