Combustion Disturbances Related to the Fuel Bed in Grate Furnaces

Other conference contribution, 2005

Combustion in grate furnaces is a common method for conversion of biofuels to energy, especially in small-scale heat production. In these furnaces combustion instabilities in the fuel bed are often observed. Here, an inventory is presented of combustion disturbances found in the fuel bed in grate furnaces. The inventory was carried out by interviewing personnel responsible for operation of ten furnaces and by recording of the fuel bed in eight of them by a portable video camera. Combustion disturbances were experienced in all except one of the furnaces. The most common disturbances were burnouts in the fuel bed and channelling at the bounding furnace walls. These disturbances are affected by practical factors related to the operation of grate furnaces. Those factors are presented together with suggestions for measures to reduce the frequency and magnitude of the disturbances. Digital image analysis was used to detect and quantify the size and movement of local burnouts in the fuel bed in one of the furnaces. The method can be used to find the source of disturbances or to evaluate contra-measures against burnouts.