Azadeh Mirvakili

Steam methane reformers compose many tubes full of catalysts inside a combustion chamber, producing synthesis gas in tubes. The combustion chamber has burners in order to provide heat of endothermic steam methane reforming reactions in tubes. The dominant heat transfer mode between combustion chamber and tubes is radiation, and a major problem that arises in a heat radiation is emissivity factor reduction in surfaces of steam reformer along times. Therefore, the portion of radiation heat transfer decreases, and then tubes wall temperature reduces, which has a high effect on the reactions in tubes. In this work, an industrial reformer has been investigated for ten years. Computational Fluid Dynamic (CFD) is applied to compare the performance of this reformer at the first and tenth years of operation. Results show that a 10% increase in fuel consumption in the tenth year cannot compensate for all temperature drop in skin tubes, and there is still a 14 K temperature drop. Also, a 23% increase in fuel consumption can offset the temperature drop in the tenth year. Indeed, fuel consumption increases with increasing the age of reformer. Finally, applying a ceramic coating with a high emissivity factor is considered via the CFD model for the reformer in the tenth year. This change leads to an increase of about 19 K in tubes temperature in the 10th year, which is 3K more than that in the first year. It can be concluded that the ceramic coating application in the wall of the refractory of the reformer can reduce fuel consumption.