Study on Layer Combustion Characteristics of Corn Straw Pellets.

To study the influence of different excess air coefficient (α) on the layer combustion characteristics of biomass briquettes, the typical corn straw pellet fuel in the main grain production areas in Northeast China was used as the research object, and a fixed-bed test rig for biomass pellets was built to simulate of the combustion process of biomass pellets along the height of the furnace and moving direction of the grate, 25 sets of combustion tests under 5 working conditions of 30, 40, 50, 60 and 70 Nm3·h^-1 were carried out, respectively. The test data was collected by the patrol instrument, and the collection step length was 1 min. The collected data was processed and analyzed by methods such as matrix and polynomial fitting. The test results indicated that when the primary air flow (Qao) was not less than 50 Nm3·h^-1, the ignition delay time (td), flame downward propagation rate (Rf) and fuel content in ash (ηa) decreased with the increase of Qao. As Qao was less than 50 Nm3·h^-1, td, Rf, and ηa increased with the increasing of Qao. In the combustion zones of 200~150 and 100~50 mm, Rf showed a trend of decreasing and then increasing. In the combustion zone of 150~ 100 mm, when Qao was not more than 40 Nm3·h^-1, Rf increased with the increasing of Qao, and then as Qao was more than 40 Nm3·h^-1, Rf tended to be stable. It was found that when Qao was 50 Nm3·h^-1 (α was 1.163), td was 3.34 min, and the combustion temperature was higher and the time was shorter (about 45 min) than other Qao, and ηa was 0.71%, the layer combustion characteristics were more ideal than other conditions. [ABSTRACT FROM AUTHOR]