Theoretical solutions for particulate scintillation monitors

Theoretical analysis for recently developed particulate scintillation monit oring technique is presented. The technique makes use of a light beam passi ng through a stack to the opposite detector. The detector measures not only the average light intensity, but also the temporal variation in the light intensity, which is different from conventional opacity systems. The signif icant advantage of scintillation monitors is their insensitivity to lens co ntamination. However, until now theories relevant to the technique have not been found in the literature, In this article, it is first assumed that th e number of particles in a light beam passing through stack airflow is a Po isson random variable. Then, by use of Mie's theory and stochastic process theory, a mathematical model for output light intensity, the mathematical e xpectation and the variance of output light intensity are derived. Finally, an equation for calculating particulate mass concentration is obtained. Th eoretical analysis shows that scintillation monitors are insensitive to len s contamination but dependent on particle size distribution. Experiments ve rified the theoretical results. (C) 1999 Elsevier Science B.V. All rights r eserved.