Use of a Chemical‐Looping Reaction to Determine the Residence Time Distribution of Solids in a Circulating Fluidized Bed

Abstract

The residence time distribution (RTD) of solids in various sections of a circulating fluidized bed (CFB) is of great importance for design and operation but is often difficult to determine experimentally. A noninvasive method is described, for which the RTD was derived from temporal measurements of the temperature following the initiation of a chemical‐looping reaction. To demonstrate the method, a CuO‐based oxygen carrier was used in a small‐scale CFB, and measurements were made in the fuel reactor, operated as a bubbling fluidized bed. The measurements were fitted to the tanks‐in‐series model, modified to account for heat losses from the reactor. There was excellent agreement between the model and the experiment. Limitations and further improvements of the method are discussed, also with respect to larger reactors.

Solids Flow in a “Particle-in-Tube” Concentrated Solar Heat Absorber

“…The different regimes are governed by the operating conditions, reflected in a specific ( U , G ) range. The RTD in CFB applications has been studied by mostly tracer experiments. ,− Simulations were also repeated by Shi et al The RTD effect on the chemical conversion in a CFB was investigated for the chemical looping combustion process. − The cumulative RTD distribution, expressed as F ( t ), determines the average residence time ( t 50 ). The slope of the F ( t ) curves provides important mixing information since a steeper slope corresponds with a more pronounced plug flow.…”