This study aims to investigate the highest temperature generated by the reaction in the high-temperature furnace and simulate the combustion of different gases and pulverized coal. We developed a program using the energy conservation principle and the adiabatic flame temperature formula of the first law of thermodynamics, utilizing VBA in Excel, to derive the highest temperature by calculating the adiabatic flame temperature at which the total outlet enthalpy equals the total inlet enthalpy. The study confirms the parameters of coke oven gas (COG), pulverized coal injection (PCI), and other gases, and lists the combustion equations to follow the law of conservation of mass. Finally, we used the Newton-Raphson method to calculate the theoretical adiabatic flame temperature.