VATIS UPDATE Article

Researchers from the Department of Atomic Energy (DAE), Government of India, have developed a flue gas conditioning technology for reduction in suspended particulate matter (SPM). The elegance of this technology is that it is simple, robust and can be implemented with minimum downtime once the initial characterization and system design is finalized scientifically based on the site specific conditions. This technology can be incorporated in new or existing installations in the country, where thermal power stations still continue to be main stay in power generation and where unfortunately coal contains high ash in some cases, excess of 40-45%.

This spin-off technology was developed by the Heavy Water Board when in one of its heavy water plants having a coal fired captive co-generation plant had an excess of SPM emission levels during its initial days (500-600 mg/nm3 compared to a limiting value of 115 mg/nm3). The most appropriate solution was to externally alter the resistivity of the ash particles in the charged flue gas medium through weak alkali conditioning agents. A pilot level study with ammonia as a conditioning agent was followed by actual plant set up based on in-house design and engineering.

A full fledged technology demonstration plant was set up for the first time in 1999 in the Captive Power Plant. Subsequent to the demonstration of this technology and completing the patenting formalities, the technology was demonstrated at some more power stations within the country with successful results. A systematic scientific approach followed at all these places in terms of selection of dosing rate, types of distributor of the ammonia and air mixture resulted in bringing down the SPM concentration in all these power stations. The comparison with other flue gas conditioning chemicals indicated that ammonia or its derivatives would be the most appropriate flue gas conditioning chemical for Indian conditions.