Prof. D. N. Singh

S. SHANTHA KUMAR

Ph. D.
Indian Institute of Technology Bombay, Powai, India sskr1@rediffmail.com

INVESTIGATIONS ON THE INFLUENCE OF FLUE GAS CONDITIONING ON FLY ASH CHARACTERISTICS

Increased population and industrial development demands sustained supply of electricity, the majority of which is produced by thermal power stations, which utilize coal as a fuel all over the world. Coal combustion results in generation of large quantities of coal residues, which contains very fine particles that tend to become air-borne and which contribute to the suspended particulate matter (SPM). Hence, in order to safeguard the environment against the emission of SPM, pollution control devices, such as cyclone separators, bag filters and electrostatic precipitators (ESPs) have been employed. In addition, flue gas conditioning (FGC), a technique that involves addition of chemical additives to the flue gas is practiced. This increases the ash collection efficiency of ESPs and thereby results in reducing the emission of SPM released into the atmosphere from thermal power stations.?
Ammonia and Sulphur trioxide are two commonly used FGC agents. It is a well established fact that utilization of the fly ash, as a cementitious material, depends on its pozzolanic characteristics, which in turn pivots on its physico-chemico-mineralogical and morphological characteristics. However, there is a concern that how these characteristics get influenced due to FGC and the presence of residual ammonia in the fly ash may adversely affect its usage as a construction material. With this in view, ash samples from various thermal power stations in India, where flue gas conditioning is being employed, were collected. The samples were examined for their physico-chemico-mineralogical and morphological properties, as well as, the concentration of residual ammonia. Based on these studies efforts have been made to highlight the influence of FGC on ash characteristics and its utilization.