CFD-modeling of critical deviations of combustion processes in pulverized coal boilers. Part 1. Construction of the TPP-210A boiler calculation model

Abstract

Purpose. Development of a mathematical model for predicting critical deviations of furnace processes during the operation of anthracite boilers converted to burning sub-bituminous coal, including in non-design modes of operation. Verification of the calculation model of the TPP-210A boiler of the 300 MW power unit on the design fuel – anthracite for further analysis of its operation on sub-bituminous coal. Methodology. Modelling of solid fuel combustion was performed with the help of finite-element CFD models of the boiler unit in the ANSYS-Fluent software complex with the determination of the relevant characteristics of the boiler. Findings. Finite-element CFD models were developed according to the working drawings of the TPP-210A boiler and its burner device, reconstructed for burning sub-bituminous coal. Verification of the results of CFD modeling was carried out for the case of burning the design fuel – anthracite in the design operating modes. It is shown that the discrepancy between the results and the experiment does not exceed 6.5 %, which allows the use of the developed computer model for simulating the burning of sub-bituminous coal, including in non-design operating modes. The obtained results are the basis for further calculations of the operation of the TPP-210A boiler of the 300 MW power unit on sub-bituminous coal with the determination and minimization of the factors of critical deviations of furnace processes that lead to thermal damage of wall screens. Originality. For the first time, CFD modelling has taken into account all the design features of the burner devices of the TPP-210A boiler, reconstructed for burning sub-bituminous coal with the introduction of a steam ejector of a high-concentration dust pipe under rarefaction to the central air channel. For the first time, the distribution of thermal resistances has been applied as boundary conditions on the walls of the fuel tank for the case of burning sub-bituminous coal. The validity of these approaches was confirmed by the verification of the results. Practical value. The verified computer model of the TPP-210A boiler of the 300 MW power unit converted to burning sub-bituminous coal will allow determining and minimizing the factors of critical deviations of furnace processes which lead to thermal damage of wall screens. This will contribute to increasing the reliability and improving the technical and economic indicators of the boilers of the Trypilska TPP, where 3 such boilers are operating, and other power plants (Zmiyivska, Kryvorizka, Prydniprovska), where similar anthracite boilers are planned to be converted to sub-bituminous coal.