Gamma Attenuation Based Consistency Measurement, 1997 Process Control, Electrical & Info. Conference Proceedings

Gamma attenuation based (or nuclear) density systems have been used in the Pulp and Paper Industry for over 35 years. They have been used primarily to measure density and % solids of various liquors, lime slurries, starches, and other applications. The density changes involved in Consistency measurements were, in the past, too small to be accurately detected by gamma based systems. Recent improvements in the sensitivity of these systems has allowed them to be used to measure the Consistency of pulp on a non-intrusive and non-contacting basis.

This new Consistency measurement technique utilizes a polyvinyl toluene scintillation detector that emits light pulses with a duration of 5 nanoseconds. This extremely short pulse duration along with an advanced pulse separation technique provides the resolution necessary to reliably perform Consistency measurements of pulp. A technical study was conducted at a U.S. Pulp & Paper Company Technology Center to evaluate the viability of using gamma attenuation to measure Consistency. Conclusions were that the measurement technique is technically sound and that it has unique advantages over traditional mechanical consistency measurement systems.