The Organization of Internal Recirculation of Smoke Gases in Reversive Water-Cooled Chambers of Combustion of Boilers for their Modernization

The given work develops the theory and studies the practical application of multichamber combustion in flue water-heating boilers. The prototype design of the secondary screen-radiator, to alter the geometry of the combustion chamber is offered. Directions for the modernization and the intensification of the heat exchange process in combustion chambers are considered and determined. It is theoretically proven, that an offered method of modernization of the combustion chamber, raises the efficiency due to an increase in the convection and radiating heat exchange and reduces the harmful emissions to atmosphere due to a change in the aerodynamics, the thermodynamics and the kinetic processes taking place in the boiler. A mathematical model is developed to determine the volume of recycled gases and the speed of aerodynamic streams in the combustion chamber and fire tube of the boiler. Calculations of the material balance of aerodynamic streams and thermal calculations for the combustion chamber with a secondary screen-radiator installed are carried out. Experimental studies under laboratory conditions are executed, from which results confirming the correctness of the chosen method for an intensification of the heat exchange process are received. The optimum geometrical sizes and construction materials for secondary screen-radiators are found. The coordinates of installation of such screen-radiators in the combustion chamber to receive the maximal positive results are determined. Changes of structure of the flame are investigated; with a sharp decrease in the emissions of NO_x and a reduction in time of heating the boiler waters is recorded. The use of CFD modeling allowed a more detailed study of the aerodynamics, thermodynamics and chemical kinetics processes that occur in combustion chambers with a secondary screen-radiator installed. The initial results of the analytical and CFD models agree to within 5%, which testifies to their adequacy.