As part of an investigation of methods for the control of sulphur dioxide emissions from stoker-fired plant, a computer-based model of combustion within the fuel bed was developed. The model was based on an existing model of coal combustion and developed to enable consideration of the fuel bed conditions in a travelling grate stoker. The model considers the fuel from the point of entry on the grate through devolatilisation, combustion and ash cooling. Heat and material balances are carried out throughout the fuel bed at selected time intervals. This enables prediction of combustion gas composition and temperature at any point within the fuel bed. As input the model requires details of coal composition, along with basic plant operational parameters such as grate speed, excess air and fuel burning rate. The model was used to predict fuel bed combustion gas composition and temperature profiles. Comparison with data obtained from operational plant and a novel fixed grate simulator showed good agreement with model predictions giving confidence in its representativeness.
