Development, Validation And Implementation Of Multiple Radioactive Particle Tracking Technique

Computer Automated Radioactive Particle Tracking (CARPT) technique has been successfully utilized to measure the velocity profiles and mixing parameters in different multiphase flow systems where a single radioactive tracer is used to track the tagged phase. However, many industrial processes use a wide range of particles with different physical properties where solid particles could vary in size, shape and density. For application in such systems, the capability of current single tracer CARPT can be advanced to track more than one particle simultaneously. Tracking multiple particles will thus enable to track the motion of particles of different size shape and density, determine segregation of particles and probing particle interactions. In this work, a newly developed Multiple Radioactive Particle Tracking technique (M-RPT) used to track two different radioactive tracers is demonstrated. The M-RPT electronics was developed that can differentiate between gamma counts obtained from the different radioactive tracers on the basis of their gamma energy peak. The M-RPT technique was validated by tracking two stationary and moving particles (Sc-46 and Co-60) simultaneously. Finally, M-RPT was successfully implemented to track two phases, solid and liquid, simultaneously in three phase slurry bubble column reactors

Hydrodynamics Investigation of Laboratory-Scale Internal Gas-Lift Loop Anaerobic Digester using Non-Invasive CAPRT Technique

Internal gas-lift loop reactor (IGLR) was used as an anaerobic digester and its hydrodynamics were studied using Computer Automated Radioactive Particle Tracking (CARPT) Technique. This paper deals with the experimental study on a laboratory-scale digester. An anaerobic digester is a three-phase system consisting of gas, liquid, and solids; however solid-liquid slurry was treated as a single phase due to smaller size and lower density of solids. The effect of various geometric and operating variables on the hydrodynamics was studied. The superficial gas velocity was maintained at very low values and IGLR was operated in bubbly flow regime, which is suitable for operation of anaerobic digesters. The flow pattern and liquid velocity profile was obtained and effect of gas superficial velocity, draft tube diameter, type of sparger on liquid velocity and dead volume was studied in detail. Mean circulation times were calculated and compared for different digester configurations. Results showed that the increasing gas velocity increases the liquid velocity, decreases circulation time but does not offer any significant advantages in reducing the dead volumes. The configuration with draft tube diameter to tank diameter ratio of 0.5 showed good liquid circulation throughout the digester volume and low mean circulation time implying better mixing

Water Science and Technology

Sludge management in waste stabilization ponds (WSPs) is essential for safeguarding the system performance. Sludge accumulation patterns in WSPs are strongly influenced by the pond hydrodynamics. CFD modeling was applied to study the relation between velocity profiles and sludge deposition during 10 years of operation of the Ucubamba WSP in Cuenca (Ecuador). One tracer experiment was performed and three sludge accumulation scenarios based on bathymetric surveys were simulated. A residence time distribution (RTD) analysis illustrated the decrease of residence times due to sludge deposition. Sludge accumulation rates were calculated. The influence of flow pattern on the sludge deposition was studied, enabling better planning of future pond operation and desludging.Cuencavol. 66; no. 1