PHYSICAL AND NUMERICAL MODELLING OF HEAT-FLOW PROCESSES IN TANGENTIALLY PULVERIZED FUEL-FIRED BOILER

Abstract

The paper presents results of three-dimensional physical modelling and computer simulations of fluid-flow structures, mixing and combustion processes in a 125MW tangentially fuel-fired boiler and additional fuel – natural gas. This method is commonly called the reburning process, with an emphasis on the reduction of CO, NO_x and SO_x. The co-firing process is realized between the main coal burners and additional fuel nozzles. To improve the mixing and combustion processes, a physical technique, the so-called acid/alkali technique, is used to optimize the placement and direction of additional air and fuel nozzles. The best result obtained from physical modelling experiments is studied using numerical simulations with the FLUENT commercial code. Numerical modelling results are then used to analyze the performance of an industrial boiler. These results, compared with measurements in a real boiler, seem to be in good agreement with each other.