December 08, 2021

Numerical Simulation of Two-Dimensional Flow Field in FLS Decomposition Furnace

As we all know, the decomposition furnace is the key equipment of the precalciner kiln, with various functions such as fuel combustion, gas-solid heat transfer and carbonate decomposition. The completion of these functions requires certain circumstances and conditions. From the analysis of material stress, gas turbulent flow determines the effect of material dispersion and mixing; from the perspective of gas-solid heat transfer, gas turbulent motion is the decisive factor of heat transfer and decomposition. Therefore, to study the function of the decomposition furnace, we must first study the three-dimensional flow field of the gas turbulent motion in the decomposition furnace, so that the velocity field can reach a reasonable uniform distribution. Study the advanced of the turbulent flow field and give the axial velocity distribution. Give the radial velocity distribution. Given the combined velocity vector of axial velocity and radial velocity, it can be seen from the velocity profile that the axial velocity is large and the radial velocity is small. The axial airflow is injected into the furnace from the inlet and forms a central part. In the ascending stream, the axial velocity at the center gradually decreases, and a negative velocity distribution appears near the wall of the decomposition furnace, indicating that there is a downward flow, that is, the gas has a reflux motion, indicating that an annular vortex is formed along the entire circumference of the furnace. The presence of the eddy current will add back material to the material, prolong the residence time of the material, and is beneficial to fuel combustion, gas-solid heat transfer and carbonate decomposition in the furnace. And the distribution of the turbulent flow energy and the turbulent flow energy dissipation rate are given separately. The distribution of these two parameters on the same section is smaller on the axisymmetric line and the side wall, and the middle part is larger, especially in the lower part of the furnace body. Higher turbulent flow energy and enthalpy flow energy dissipation rate areas will be more favorable for material dispersion if it is cut here, which is consistent with the results of cold model simulation experiments.

5 Conclusions This paper uses a two-dimensional turbulence model to numerically simulate the gas turbulent flow field in the FLS decomposition furnace, and uses the finite difference method to solve the gas velocity field. The simulation results show that the gas forms a blasting layer at the inlet, forms a recirculation zone at the wall surface, and has a high turbulence intensity in the lower part of the furnace body. If it is cut here, it is advantageous for material dispersion and heat exchange.

The gas turbulent flow field in the decomposition furnace plays a decisive role in fuel combustion, gas-solid heat transfer and carbonate decomposition. It is important to correctly describe the turbulent motion of the gas in the decomposition furnace. The analysis of the gas velocity distribution in the FLS decomposition furnace has certain guiding significance for further understanding the combustion, heat transfer and decomposition in the decomposition furnace, and is of great significance for optimizing the structural design of the decomposition furnace.

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