Co-firing Coal and Straw in a 150 MWe Utility Boiler: Deposition Propensities

In order to meet a 20 % reduction in CO2 emissions, based on 1988 levels, by the year 2005, the Danish Government has committed the power companies in Denmark to burn 1.2 million tons of straw per year from the year 2000. A conventional pf-fired boiler at the Danish Power Company Midtkraft has been converted to coal-straw co-combustion and a two year demonstration programme was initiated in December 1995. As part of the demonstration programme, a comprehensive investigation of ash deposition propensities is conducted in the spring of 1996. The investigation is based on deposits collected on temperature controlled probes and in-situ measurements of flue gas temperature, flue gas compositions including alkali metal concentrations and particle and aerosol loading and composition. The study is carried out as collaborative research projects between the Midtkraft Power Company and the Combustion and Harmful Emission Control (CHEC) Research Programme at the Department of Chemical Engineering, Technical University of Denmark. This paper gives an introduction to the collaborative research project concerning ash deposition propensities.