Steam methane reforming is utilized to synthesis gas production in methanol industry. The reformer furnace contains a combustion chamber which has tubes filled with an alumina-based nickel catalyst, the heat required to perform the catalytic reaction using the burners inside the chamber combustion is supplied. In this work computational fluid dynamics is applied to three dimensional simulation of the furnace chamber. Gas distributions and temperature inside the furnace is considered and results are validated with industrial data. Results show that gas distributes uniformly in the furnace and temperature is uniform.