Mathematical model for a single screw ash cooler of a circulating fluidized bed boiler

The paper presents the mathematical model of the heat transfer processes for a single screw ash cooler (SSAC) working with a circulating fluidized bed (CFB) boiler. The validation of the model is based on experimental measurements made on a 230 MWe power unit. The analysis of measurement data from two bottom ash coolers showed that the correct prediction of the outlet temperatures of ash and cooling water requires the determination of their individual ash filling characteristics (i.e. coolers). The numerical results confirm that the mixing model proposed by Schlünder correctly predicts the heat transfer coefficient for ash. The described mathematical model can monitor the operating conditions of the single screw ash cooler. It enables the determination of the optimal volumetric flow rates of the cooling water in order to get its highest possible outlet temperature, and then for this water to be used, e.g. for sanitary purposes. [Display omitted] •Mathematical model of ash cooler is successfully verified with experimental data.•Schlünder model of particle mixing is used to calculate heat transfer coefficient.•Characteristic of filling ash cooler with ash is a key part of mathematical model.