(617a) Elutriation Comparison of Particle Separation Systems for Chemical Looping Applications

Fluidized beds are used in many industries for their favorable characteristics of good solids mixing, high rates of heat and mass transfer, and large throughputs. One process of interest is Chemical looping combustion (CLC) reactor systems, which are a recent technology for electrical generation. One process of interest is Chemical looping combustion (CLC) reactor systems, which are a recent technology for electrical generation. One difficulty in the development of this technology is the removal of ash and unburnt carbon (or char) from the oxygen carrier material prior to re-entering the air reactor in coal or other solid fuel applications. Carbon allowed to traverse to the fuel reactor results in lower capture efficiencies – CO2 emissions. To address this issue, several cold flow experimental efforts are being undertaken at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL) towards the development of effective particle separation techniques. This work focuses on the study of the hydrodynamics and elutriation characteristics of a mixture consisting of fine (<50μm) particles (serving as a char analog) and larger (~600μm to ~800 μm) particles (serving as the carrier analog). The systems being compared are a 0.1 m meter diameter bubbling bed with a 0.9 m height and a novel riser design called a carbon stripper. The carbon stripper feeds the gas and particle mixture into a conical inlet section with a centralized jet feed and an annular gap between the wall and cone. A sweep gas within the annular gap is present to aid in the separation. The important comparisons are the separation efficiency, the rate of elutriation of fines, and cost of fluidization. The target separation efficiency for the mixture is 80%, with an elutriation flux of 0.5 kg/m².