Computer Control of Solid Fuel Bed Fired Boilers

Stoker boilers are a class of boilers in which a solid fuel, such as coal or bark, is burned in suspension as well as on a grate. Air is admitted both under and over the fuel grate. In order to achieve an optimum combustion efficiency the presented control scheme uses steam flow, fuel flow, CO, CO2 and opacity measurements for distribution of the under-grate and overfire air-flows. The control scheme includes on-line identification and hill climbing techniques for the optimum excess air distribution. This scheme also minimizes undesirable pile up of fuel on the grate. The paper also discusses results from this control scheme with stoker coal and bark boilers.