Development of a novel measurement method for residence time distribution in circulating fluidized bed reactors

Previous investigators measured the residence time distribution (RTD) of particles in the riser of a circulating fluidized bed (CFB). However, there has not been a systematic study regarding RTD of particles over an entire CFB reactor. The work. presented here analyzes the RTD of sand particles, with an average particle size of approximately 200{dollar}mu{dollar}m, in a CFB with a 2.7 m tall riser and 11.43 cm in diameter. A solids flux of roughly 30 kg/m{dollar}sp2{dollar}-s and an average gas velocity of roughly 4m/s, approximated mineral processing conditions (e.g. ore roasting). The size of the tracer pulses employed were targeted in a way that single pass RTD could be extracted. A mathematical process for the extraction of single pass RTD data from a composite RTD curve was analyzed. The gamma distribution curve showed good promise in fitting typical single pass RTD over CFBs. A convolution process of the single pass RTD into a composite RTD was also outlined. The overall RTD for the CFB was also modeled as a CSTR, which showed a good correlation, particularly as time increased.; To obtain tracer information, a novel method for measuring tracer content in a particulate stream was developed successfully. The new method is based on the gasification of tracer and measuring the gas volume evolved. The results obtained show very good correlation with a more precise and expensive tracer analysis method.