Combined Combustion of Various Industrial Waste Flows in Boiler Furnaces. Part 3

Abstract

To solve the problem of useful utilization (by combustion in heat generators) of liquid and gaseous industrial waste (that was defined in Part 1 of the present article), heat transfer processes in heat generating units were considered in Part 2. The main equipment for the effective solution of this process is a burner device and a combustion chamber with heat transfer to an external heat carrier, for example, a boiler furnace or a heat recovery boiler. The present article considers an example of calculating such a process for a distinctive mixture of waste from a chemical industry enterprise using modeling of possible schemes of a flame combustion system for a characteristic combination of various types of gaseous and liquid combustible products. For this purpose, the CFD (Computational Fluid Dynamics) computational hydrodynamics method was applied, which is determined to be the most effective one, in analyzing the behavior of media flows and combustion processes. CFD analysis makes it possible to predict hydrodynamic and thermal processes (especially in complex multicomponent systems) and optimize them to achieve the best results. The most important factor in high-quality combustion is the atomization process (fine atomization) of highly viscous liquids with high surface tension coefficients. The ultrasonic me-thod has been adopted as the most effective for such liquids. Besides, the quality of the distribution of flows of combustion mixtures and flue gases in the combustion chamber is considered. For doing this, it is necessary to arrange separate flows of axial and peripheral air, which make it possible not only to change the configuration of the flame, but also to direct convective flue gas flows to the most efficient areas of the combustion chamber. The article considers various options for heat transfer (convective and radial) depending on various factors, taking into account the degree of probability of formation of pollutants (primarily NOx) in combustion products. The results of the numerical solution of the problem are presented. The analysis of the results on the optimal ratio of the shares of primary and secondary air flows for combustion was carried out. In conclusion, a comparative analysis of the options for burning fuel directly in the boiler and in the pre-combustion chamber is presented. The efficiency of direct combustion has been demonstrated.