Experimental observations on directly irradiated conical spouted and spout-fluid beds

This paper presents the experimental results obtained in directly irradiated conical spouted and spout-fluid beds. A conical bed with a minimum and maximum inner diameter of 80 and 314.76 mm was filled with SiC particles and directly irradiated from the top with a beam-down reflector with a 2 kW Xe-lamp. The study examines the influence of the bed height and airflow rate on the temperature distribution over the top surface of the bed (where the concentrated irradiation impinged), measured with an infrared camera. In addition, two type of beds were compared: conventional spouted and spout-fluid beds. The heat exchange of the concentrated radiative flux over the fluidized particles in motion under the action of fountain bursting was assessed by characterizing the temperature of the particles (Probability Density Function, mean value and standard deviation). The results of this work show that the spouted bed can reduce the maximum temperature of the particles, especially in the case of shallow beds. The behavior in the two cases is different, with the exception of the deep bed, where the spouted bed presents slightly lower homogeneous temperatures than the spout-fluid bed (reducing the appearance of hot spots) and with an associated reduction of 52.28 % in the pumping costs. Spout-fluid temperatures strongly depend on the air velocity and the height of the bed of particles, exhibiting a wider temperature range than the spouted case due to the different fluidization regimes observed.