Fluidization and Combustion Characteristics of Pine Needles in Fluidized Bed Combustor: An Experimental Investigation

Abstract

Pine needle (PN) from the coniferous forest has enormous energy potential in Himalayan territories. The present study investigates the fluidization and combustion characteristics of PN in FBC. It is done in four steps: 1) Thermogravimetric Analysis (TGA) 2) cold-state characteristics 3) combustion tests 4) fly-ash analysis. At first, TGA demonstrates the physicochemical changes and confirms ignition, rapid devolatilization and combustion points for PNs. At second, Experiments on the cold-state show the mixing characteristics of PNs with silica sand indicates that the 3.00 mm PNs with 2% concentration mix well with bed material at fluidization number (FN=4). However, improper mixing was found because of little segregation above and below FN=4. Followed by the combustion tests (third step), in which the temperatures of the dilute phase region were found to higher than the combustion zone and secondary air have no significant effect on flue gas temperature. Additionally, the combustor had achieved combustor efficiency (?Combustion) over 73.19%. The ash related problem had not appeared at the operating temperature range between 700-940ºC for 16 hours. At last, the fly ash suggests the combustor performance with the help of Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS), and Ash Fusion Temperature (AFT).