Comparison in the physicochemical and microstructural characterization of waste coal combustion residues (CCR) generated from fbc and pcc boiler using the same origin of coal

Abstract

In the present study comparison in the physicochemical and microstructural characterization of waste coal combustion residues (CCR) generated from fluidized bed combustion (FBC) as well as pulverized coal combustion (PCC) boiler was done. CCR were collected from two different types of the boiler having an almost same capacity as well as uses the same origin of coal for combustion. Due to lower temperature in FBC boiler, generated CCR are relatively denser in structure as comparison to CCR generated in PCC boiler. The generation of temperature is more than the ash melting temperature in PCC boiler which results the presence of alumina and silica in CCR as combined form of aluminosilicate. In FBC boiler, due to lower temperature, CCR have silica and alumina in free form. Oxides of both CCR like silica, alumina, and iron oxide are same but its percentage quantity is different in each CCR. Heavy metal content (like iron) is higher in bottom ash than fly ash in both PCC as well as FBC. At high temperature, ash got melted, and volatile material got entrapped to form cenosphere in PCC boiler which causes hollow cenosphere in major quantity. In FBC boiler, mainly solid structure of Fly Ash is observed due to absence of such phenomenon for lower temperature generation. Due to the presence of aluminosilicate in PCC Fly Ash, it can be used as a hard wear-resistant material. On the other hand, presence of free, uncombined alumina and silica in FBC Bottom Ash can facilitate for easy recovery of alumina, silica. Based on the different physicochemical properties it can be concluded that these wastes (CCR) should be exploited for preparing commercially viable products like bricks, tiles etc. apart from land filling. It will also control environmental problems by avoiding solid waste dumping. © 2018 Widener University School of Civil Engineering. All rights reserved.