99/00596 FLASHGRAN—an efficient way for utilization of furnace wastes from fluidized bed boilers

Abstract

In spite of considerable development in fluidized bed combustion technique since the beginning of eighties, the properties of furnace wastes and possibilities for their utilization have not yet been fully explored as they have for wastes from pulverized fuel combustion. In 1991, the start-up of the first Polish fluidized bed boiler, AKF-c 5 MWt at the Debiensko Mine, followed by construction of large industrial boilers made it possible to characterize such wastes and to investigate solutions for their utilization. Based on acquired experience in processing of industrial waste, the Institute for Chemical Processing of Coal (IChPW) in cooperation with RAFAKO S.A. has developed and implemented on the pilot scale the technology for processing and utilization of fluidized bed ash as the material for hydraulic filling of voids from mining operations. The technology gained the name FLASHGRAN, based on fluidized bed ash granulation. During operational trials of the circulating boiler at Debiensko, hard coal, brown coal and anthracite were used as fuel. The paper presents the results of investigations performed for hard coal from the Debiensko Mine. As a sulfur acceptor, limestone with CaCO{sub 3} content >80% was used. The solid waste from the boiler consisted of fine-grained fly ash frommore » the ESP (70%) and ash drained from the bed. The chemical properties of the produced wastes are listed in a table. Aluminosilicates represented about a half of the entire ash amount. The high content of anhydrite and presence of free active lime in ash cause its hydraulic activity and differentiate it from the silicate type of fly ash from pulverized fuel combustion of hard coal.« less