Cold modeling investigation of aerodynamic characteristics of an arch-fired boiler on particle image velocimetry (PIV): Influence of momentum flux ratio of arch air to secondary air and secondary air angle

Abstract

To study the aerodynamic characteristics, experiments were carried out on a laboratory-scale model for an arch-fired boiler. The airflow velocity was measured by using a two-dimensional PIV. The results show that: (1) as the momentum flux ratio increases, the arch air becomes stronger and reaches deeper into the furnace; however, the velocity distribution was non-uniform in the lower furnace, and the recirculation region expanded slightly. The ideal value of the momentum flux ratio is 2.54. (2) As the low layer secondary air is injected with an inclination angle, its mixing with the arch air is postponed. So, the gas after mixing can reach the lower furnace and the residence time of fuel is prolonged. As the inclination angle increases from 0° to 20°, 30° and 40°, respectively, higher penetration depth and fullness degree of airflow can be obtained as well as the larger recirculation region. The ideal inclination angle is 30°; and (3) Compared with increasing the momentum flux ratio, adjusting the secondary air inclination angle is more beneficial to improving the distribution of the airflow within the furnace.