Optimization and simulation of low-temperature combustion and heat transfer in an Uhde carbonization furnace

The temperature distribution inside a low-temperature combustion chamber with circuited flame path during the low temperature pyrolysis of lignite was simulated using the computational fluid dynamics software FLUENT. The temperature distribution in the Uhde combustion chamber showed that the temperature is very non-uniform and could therefore not meet the requirements for industrial heat transfer. After optimizing the furnace, by adding a self-made gas-guide structure to the heat transfer section as well as adjusting the gas flow size in the flame path, the temperature distribution became uniform, and the average temperature (550–650 °C) became suitable for industrial low-temperature pyrolysis. The Realizable k-epsilon model, P-1 model, and the Non-premixed model were used to calculate the temperature distribution for the combustion of coke-oven gas and air inside the combustion chamber. Our simulation is consistent with our experimental results within an error range of 40–80 °C. The one-dimensional unsteady state heat conduction differential equation ρcoalCcoal∂T∂t=∂∂x(λ∂T∂x)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathop \rho \nolimits_{coal} \mathop C\nolimits_{coal} \frac{\partial T}{\partial t} = \frac{\partial }{\partial x}(\lambda \frac{\partial T}{\partial x})$$\end{document} can be used to calculate the heat transfer process. Our results can serve as a first theoretical base and may enable technological advances with regard to lignite pyrolysis.