Modern Methods of On-Line Size Analysis for Particulate Process Streams†‡

Two techniques for on-line particle size measurement are evaluated on the reproducibility of their volume distribution determinations. A forward scattering laser light devise is interfaced with a dilutor to examine the potential of this technique for high concentration streams. The forward scattering instruments are capable of outputting extremely reproducible distributions and here we show that when the dilutor is well designed, the on-line instrument can have similar performance. We compare this with a scanning back scatter instrument which is directly inserted in highly concentrated slurries. We present the methods used to improve the robustness of the conversion of the output of the back scatter instrument to volume distributions. The output of the back scatter instrument is inherently less stable but with the proper methods one can obtain reproducibilities of the order of 2 to 6 percent.