Application of the zone-by-zone optimization method and a simplified numerical model for the efficient solid fuel combustion schemes development using direct-flow burners and nozzles

The article considers the application of two approaches to optimizing the direct-flow burners and nozzles location using numerical simulation. The study objects are two furnaces of the traditional and invert type with solid slag removal for boilers for supercritical and ultra- supercritical steam parameters, respectively. The lean hard Kuznetsk coal was used for both cases, somewhat different in characteristics in the cases under consideration. This coal type is currently burned mainly in furnaces with liquid slag removal. The use of the zone-by-zone optimization method implies a sequential each pre-selected zones optimization of the furnace in the direction of flue gas movement with modeling of the solid fuel combustion process with different burner and nozzle layouts. A dimensionless scheme for burning coal dust in a traditional furnace with an upward flue gases movement has been developed. The use of a simplified numerical model (SNM) due to certain settings made it possible to approximate the results of furnace aerodynamics modeling without taking into account the chemical reactions to the results with combustion simulation, which significantly reduced the conducting research time. As a result of modeling the invert furnace aerodynamics, the optimal arrangement of direct-flow burners and nozzles was selected. The article discusses the main features of each research method use, optimization criteria, research objects, initial combustion schemes, design parameters of combustion schemes that are changed during optimization, as well as the main results of the optimization. The solid fuel combustion schemes obtained using two approaches to conducting research using direct-flow burners and nozzles ensure the operation of the considered furnaces with better values of efficiency and environmental indicators than traditional combustion of similar fuel in furnaces with liquid slag removal. The obtained values are at a level acceptable for the Russian Federation.