CFD MODELING OF WATER HEATING BOILER OPERATION WITH DIFFERENT TYPES OF FUEL PELLETS

In this study, computational fluid dynamics (CFD) modeling methods were used to investigate the combustion features of different fuel pellets used in a solid fuel boiler. The ANSYS Fluent software program and finite-element CFD models of the boiler unit were employed to develop the calculations. The results of the CFD modeling were verified in the boiler SET-25 computer model according to the passport data. The verification was performed for combustion of hardwood pellets. The results obtained shown that the discrepancy did not exceed 2%, which indicated that the proposed approach can be used to model the combustion of other common types of pellets (e.g., rape straw, poultry litter, sewage sludge, and different types of mixed wood chips). The developmental characteristics and combustion front size were determined. The largest size of the flare was inherent in burning mixed wood of different types. In this case, the size of the flare was - 250 mm in diameter, and the height of the front was - 500 mm. The most compact flare was observed during combustion of pellets from sewage sludge, in which the height was - 300 mm and the maximum diameter was - 70 mm. Analysis of the temperature distribution of the combustion products in the gas path of the boiler showed that the technological parameters need to be changed and new performance charts for each type of fuel need to be developed. The obtained results of the thermal and technical characteristics of the water heating boiler operation can be useful when designing and constructing new water heating boilers and in verifying the calculations of existing boilers. © 2023 by Begell House, Inc.