In situ measurement of catalyst tube emissivity by means of a portable solid integrating sphere reflectometer

The results of the in situ measurement of the emissivity distribution of catalyst tubes in a large petrochemical reformer are presented. Knowledge of this distribution is fundamental to accurate temperature measurement through radiation thermometry, particularly in the presence of large reflection errors. It is shown how the uncertainty in emissivity propagates to the uncertainty in temperature, and that in many cases the contribution of the emissivity uncertainty dominates the total uncertainty. A novel type of reflectometer based on a solid integrating sphere was developed to perform the emissivity measurements. A description of this instrument is also given.