Development of a universal model for numerical analysis of firebox processes in heat-generating plants

RELEVANCE. A reliable mathematical description of the processes accompanying unsteady flows of reacting combustible gas mixtures is relevant for a wide range of tasks related to furnace technology and heat generating plants. The development of a tool for numerical simulation of boiler processes will make it possible to predict the modes and operating conditions of their elements in order to improve the technical and economic performance of the installation as a whole. PURPOSE. Development of a mathematical model describing threedimensional unsteady flows of a reacting mixture of gases in combustion chambers, boiler bundles and flues of boiler units. The possibility of applying S.K. Godunov's method to numerical modeling of processes in furnace devices and convective elements of a boiler unit is considered. METHODS. The complexity of modeling furnace processes is related to their nonstationarity, the complexity of the configuration of the computational domain, which requires solving the problem in a three-dimensional formulation, the course of the combustion process and the presence of associated heat exchange processes with boiler elements. Therefore, the mathematical model describing the flows of a reacting mixture of gases in combustion chambers, boiler bundles and flues of boiler units includes three-dimensional unsteady NavierStokes equations of energy and turbulence. The process of natural gas combustion in a firebox is described within the framework of a simple chemically reactive system (SCRS). To account for the combustion process, it is proposed to add to the energy transfer equation a source equivalent to diffusion combustion under the assumptions of SCRS. To numerically implement a mathematical model of processes in boiler elements, the S.K. Godunov method was used in combination with the MUSCL scheme, which provides a second-order approximation of difference equations. RESULTS and DISCUSSIONS. A mathematical model suitable for calculating the processes of hydrodynamics and heat and mass transfer in water-tube boiler units has been developed and numerically implemented. Using the developed application software package, a number of calculations were performed for the KV-GM-1,25-115 hot water tube boiler. CONCLUSION. The proposed approach to solving the problem of developing a model suitable for numerical analysis of combustion processes makes it possible to obtain a universal tool for calculating and designing heat generating plants, which can be used to determine the parameters of thermal and gas-dynamic processes in boiler units. This will make it possible to improve existing structures or develop new ones with improved technical and economic characteristics, as well as identify and resolve local problems that interfere with boiler operation and are not solved using engineering calculation methods.

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