9 - Radioactive Tracer Techniques

Abstract

This chapter provides a brief overview of radioactive tracer techniques. The radioactive-tracer method was first used to study the mixing of catalysts in commercial fluidized beds in two steps. It was perfected for, fluidized-bed application through the development of a computer-aided particle-tracking facility (CAPTF). The chapter discusses the principle of radiation detection and a theoretical model of the CAPTF is presented. The instrumentation of the CAPTF and the data reduction schemes are described, and sample results obtained by the CAPTF are also presented. The factors that affect radiation measurement are relevant to the CAPTF—the characteristics of the radioactive source, the interaction of gamma rays with matter, the position of the source relative to that of the detector, the efficiency of the scintillation detector, and the dead-time behavior of the whole measurement system. The advantage of radioactive tracer techniques technique is that the flow field is not disturbed by the measurement facility and, therefore, the measurement of the motion of the tracers represents the actual movement of particles in the system. A computer-aided particle-tracking facility (CAPTF) has been developed to measure the motion of radioactive tracers in fluidized beds. This achievement was the first successful attempt to use the radioactive tracer technique to obtain detailed quantitative information on solids dynamic data in fluidized beds.