Mercury speciation in pulverized fuel co-combustion: Effect of biomass share and combustor temperature

Mercury emissions from power plants are of great concern from an environmental point of view and as a result there is emphasis to study the reduction of ongoing inputs of mercury into the environment. The chemistry affecting Hg speciation in the effluent from coal utilization is poorly understood. Moreover increased application of co-combustion in power generation makes the understanding of mercury chemistry and its speciation more difficult. The present work mainly involves bench scale studies to investigate partitioning of mercury in Pulverized Fuel Co-combustion. The combustion experiments are carried out in an Entrained Flow Reactor with a fuel input of 10 kWth. The emitted mercury from the reactor is measured on-line by a Semtech Hg 2010 mercury analyzer. A SnCl₂ loaded reduction unit is used to speciate mercury in different forms. The experiments are performed to measure ionic and elemental Hg in co-combustion of chicken manure as secondary fuel in different ratios at 1000 and 1300°C. Increase in biomass increases the concentration of oxidised mercury due to high chlorine contents. The mercury mass balance over the gas phase deviates due to mercury contents in ash. Mercury emissions in the gas phase increase with increase in the reactor temperature. The results will help in predicting different forms of mercury emitted from the furnace at desired operating conditions which will eventually form the basis to design the control strategies for heavy metal emissions.