Operation factors influencing bed agglomeration in an industrial fluidized bed boiler

• Analysis of the bed agglomeration in an industrial unit producing steam. • Deciduous or coniferous waste are co-combusted with sewage sludge. • The agglomerates collected during operation cycle are analyzed through XRF. • Potassium content of the bed material plays a significant role in the aggomerate formation. • Optimal amounts of bed drainage and sand addition are calculated. The combustion of mixtures of woody biomass and sewage sludge in industrial fluidized bed boilers often leads to sintering of the ash particles with the inert bed material. To prevent such agglomeration, the bed material is periodically drained and partially replaced with new one, generating an increasing amount of waste over the cycle. Furthermore, complete replacement of the bed material is a costly operation, including new bed material, waste disposal, and unplanned boiler shutdown. The study examines the agglomeration process in a boiler unit installed at the thermal power plant N°3 of Arkhangelsk Pulp and Paper Mill JSC, Russian Federation. The main operating parameters of the fluidized bed unit were collected using stationary measuring devices installed in the boiler. The proximate analyses of deciduous or coniferous wood waste and sewage sludge were investigated. The elemental composition of bottom ash and agglomerates collected at five days during an operating cycle of the boiler between two complete drainage operations was studied by X-ray fluorescence spectroscopy. This work provides valuable information on the agglomeration process of the bed material in industrial boilers operating under fluidized bed conditions, thus enabling the formulation of recommendations for an optimal behavior of the boiler.