THE SHAWVILLE COAL BIOMASS COFIRING TEST - A COAL/POWER INDUSTRY COOPERATIVE TEST OF DIRECT FOSSIL-FUEL CO2 MITIGATION/

Under the sponsorship of the Pennsylvania Electric Company (Penelec), and with the support of EPRI, the U.S. Department of Energy, and the P ennsylvania Department of Conservation and Natural Resources, Penelec and Foster Wheeler Environmental Corporation conducted low percentage (3% by weight) wood cofiring tests at Units 2 and 3 of the Shawville G enerating Station in November 1995. Unit 2 is a 138 MWe (gross) wall-f ired pulverized coal boiler equipped with ball and race mills, table f eeders, and low-NOx burners. Unit 3 is a 190 MWe (gross) tangentially- fired pulverized coal boiler equipped with bowl mills, paddle feeders, and low-NOx burners. There is no spare capacity in the pulverizing sy stems of either unit when operating under full load conditions. This p roject was unique in a number of respects, expanding the knowledge and cofire experience base achieved in other previous projects (ref 1). F irst, the project tested the use of blended biofuels in boilers equipp ed with low NOx burners. Additionally, three types of biofuel were tes ted: (1) mill waste sawdust, (2) utility right-of-way trimmings, and ( 3) harvested hybrid poplar. Biofuels were processed off-site, blended at a nearby coal blending yard, and then trucked to the unmodified Sha wville Station on a ''just-in-time'' schedule basis. The off-site fuel preparation and blending operations provided an adequate supply of bl ended biofuel and coal to allow the project to meet its overall test o bjectives, and also provided much useful new data and information need ed to help establish commercial processing facilities. Plant operating technical objectives were to determine the impacts of using low perce ntage biofuel blends on boiler capacity, efficiency, stability, temper ature, and air/solid waste emissions. Significant boiler capacity limi tations were experienced on both units when cofiring 3 percent biomass blends. The 138 MWe boiler lost 8-10 MWe of capacity due to feeder li mitations, and the 190 MWe boiler lost 15 MWe of capacity due to signi ficant reductions in mill outlet temperatures. For both units, the 3 w eight percent biofuel blends behaved like wet coal. Significant new in formation was developed with respect to both fuel processing and plant performance issues. This paper describes the project and the test res ults and explores the CO2 mitigation impacts of firing blends of coal and biomass that are prepared off-site. (C) 1997 Elsevier Science Ltd.