Dry Lignite Cofiring in a Greek Utility Boiler: Experimental Activities and Numerical Simulations

Abstract

Lignite predrying and dry lignite firing is considered as an important development step for the next generation of lignite power plants. The integration of a predrying system in future lignite power plants, which utilizes low temperature steam for the drying process, combined with the further thermal utilization of lignite’s evaporated moisture, may bring an efficiency increase of four to six percentage points compared with today’s state of the art. Firing predried lignite is however expected to cause certain changes in the combustion behavior of large scale boilers. The investigation of these changes in an existing Greek utility boiler through experimental activities and numerical simulations is the scope of the present work. The investigations take place in a 75 MWth lignite fired Greek boiler. The specific unit is equipped with dedicated dry lignite burners. The measurements are performed with a dry lignite thermal share of 6%. Higher cofiring thermal shares of up to 20% are further simulated and the e...