COAL PULVERIZER MODIFICATIONS TO ENABLE 100 BIOMASS PELLET FIRING

摘要

Ontario Power Generation continues to explore options to repower its coal‐fired fleet given provincialregulation to cease electricity generation from coal by the end of 2014. In the case of the OPG ThunderBay Station, part of this effort involved significant engineering studies to evaluate the potential toconvert the boilers designed for lignite coal to fire 100% wood pellet fuel. Several utilities in Europehave successfully employed modified coal pulverizers to handle pure wood pellets and OPG has hadsome success with testing this approach within its internal biomass development program. However,there appears to be no prior experience with the use of RP style pulverizers such as those installed atThunder Bay GS. To address this technical gap, OPG worked with Alstom Power to evaluate thecapability of the RP design to grind and deliver wood pellets at the throughput necessary to completelydisplace coal. Alstom employed a combination of prior experience, CFD and pilot mill testing to assessthe limitations of the existing RP design for wood pellet firing. This paper will discuss the observationsfrom this development work and consider the modifications deemed necessary to address the issues ofsafety, capacity and operational flexibility.