An Intelligent Methodology for the Co-Combustion of Blends of Coal and Unprepared Biomass

This paper describes the development of an intelligent software based operating strategy to enable chain grate stokers to burn various blends of unprepared biomass with the minimum proportion of support fuel required to achieve a desired boiler output and thermal efficiency. A series of commissioning tests were conducted on a 880kWth chain grate stoker-fired hot water boiler to investigate the combustion characteristics of the boiler when burning various blends of unprepared biomass of varying moisture content with a support fuel over a wide range of boiler operating conditions. A fuzzy logic-based operating strategy developed using the data and operational experience gained from the tests has been implemented into a spreadsheet and was used to validate untested blends of unprepared biomass of different moisture content with the support fuels. This information on the required blend ratio and stoker operating parameters will enable operators of chain grate stoker-fired boilers to maximise the use of unprepared biomass. In summary, the work has been able to demonstrate that it is possible to efficiently co-fire unprepared, high moisture content biomass with support fuels on a chain grate stoker.