When moving towards CO2 neutral biofuels, fluidized bed combustion represents a good and flexible combustion technique. Biofuels typically have a high volatile content and varying moisture content. Fluidized bed combustion can provide even combustion conditions regardless of big variations in the fuel quality and fuel properties. However, compared to conventional fuels, biofuels often contain high amounts of chlorine and alkali metals, which set certain challenges for the boiler design. The problems that might occur due to high alkali and chlorine levels in the fuels are mainly slagging, fouling, corrosion and bed sintering. Since the variations in fuel properties between different fuels are big, it is of outmost importance from the boiler manufacturer’s point of view, to be able to predict the behavior of a specific fuel or fuel mixture in a very early stage of boiler design. For this purpose different kinds of calculation and prediction tools are needed. For prediction of slagging and fouling an ash behavior prediction tool has been developed. The prediction routine is based on advanced multi-phase multi-component equilibrium calculations, using the fuel composition and combustion conditions as input. Based on the calculations, the rate of deposit formation, the composition of the deposits and the corrosivity of the deposits at different locations in the boiler can be estimated. The prediction tool can be used in boiler design for defining the optimum arrangement of the superheaters, maximum flue gas temperature in the superheater area and maximum steam temperature. It can also be used for specification of maximum limits of troublesome high alkali, high chlorine fuels in fuel mixtures. In this study the prediction routine has been performed for three biofuels / biofuel mixtures. The calculated results have been evaluated with full scale and pilot scale probe measurements as well as with full scale long term operational experience.
- Advanced Energy Systems
Prediction of Ash Behavior and Deposit Formation in Fluidized Bed Combustion of Biofuel Mixtures
Enestam, S. "Prediction of Ash Behavior and Deposit Formation in Fluidized Bed Combustion of Biofuel Mixtures." Proceedings of the 18th International Conference on Fluidized Bed Combustion. 18th International Conference on Fluidized Bed Combustion. Toronto, Ontario, Canada. May 22–25, 2005. pp. 563-572. ASME. https://doi.org/10.1115/FBC2005-78137
Download citation file: