Capture and migration of particulate matter in activated carbon sintering flue gas purification system based on ultra-low emission target

Abstract

By using alkali metal K as the tracer component of sintered ash, the particulate matter (sintered ash and activated carbon powder) in the industrial two-stage moving bed purification project of sintered flue gas was studied. First, the distribution of K element in the gas phase and each link of the purification system was investigated. The material flowing direction as well as the trapping and releasing mechanism of sintered ash in the purification system were analyzed by BET, XRD, and SEM-EDS techniques. The migration and release rule of activated carbon (AC) powder from moving bed to gas phase was investigated, and the contribution of AC powder to flue gas particles and the key release link were clarified. The results showed that the sintered ash capture rate in the primary adsorption tower of AC was as high as 99.7%, while 65.92% of the sintered ash was captured in the middle chamber of the primary adsorption tower. Sintered ash is trapped by AC at 0–0.5 mm on the surface, which suggested the main trapping mechanisms are inertial collision and interception diffusion settling. The trapped sintered ash is recycled through the system with the AC, and eventually 99.9% ash is discharged with the sieved carbon powder from the desorption tower. The percentage of charcoal powder in the exit flue gas particulate matter is 55.45% and the release of activated charcoal powder to the gas phase in the secondary adsorption tower. Which is the key link affecting the exit flue gas particulate matter concentration. This study elucidates the capture and migration law of particulate matter in AC flue gas purification system, and provides a strong basis for the improvement of technology to achieve stable ultra-low emission of particulate matter from AC system.