Particle deposition on optical pyrometer lenses: an illustrative case study

The most important issue with the application of optical pyrometry is the particulate contamination of the systemʹs lens. This results in measurement errors and seriously degrades the instrumentʹs operational performance. This paper will illustrate the fouling mechanism, through the flow field and particle trajectory investigation of a pertinent case study, together with an analysis of the deposits that constitute the fouling of the pyrometer lens. It will be shown that the predominant flow feature within the purging system is a swirl pattern that develops at the mouth of the unitʹs still tube. This feature has the ability to draw contaminant particles down onto the pyrometer lens thus significantly increasing the likelihood of particle deposition.