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Jet attrition characteristics of chemical looping oxygen carriers and CO2 sorbents

University of British Columbia

Sorption-enhanced chemical looping reforming is a process with the potential to produce synthesis gas (syngas), mostly a mixture of CO and H₂, from hydrocarbon fuels, without having to separate O₂ from air. In this system, particle attrition is an important consideration due to the high gas velocity and chemical reactions, affecting reactor performance, operating conditions and material loss by entrainment and elutriation. Fundamental studies on jet attrition with iron as oxygen carrier and limestone as CO₂ sorbent were carried out with varying temperature, jet velocity, duration, solid species weight fraction and the presence of chemical reactions to understand how these various factors affect attrition. Experimental investigation included comparing SEM images and PSD data before and after attrition, and particle size changes with different operating conditions. Furthermore, crushing strength and breakage energy tests were determined with a compression unit to understand how material properties affect particle attrition. In addition, for in-depth fundamental attrition studies on material properties, porosity, specific surface area and pore size distributions were measured to investigate the effects of chemical reaction on attrition. Based on the experimental findings, a mechanistic jet attrition model (JAM) was developed to improve the understanding of jet attrition and predict the particle size distribution in fluidized systems, considering that particle attrition was affected by changes in various operating conditions, such as time, temperature, gas phase species concentrations, reactions and particle composition. Material property changes were considered, as well as how both fragmentation and abrasion affect fluidized bed systems. A novel mechanistic model for attrition was suggested, allowing for variations of material properties, chemical reactions, and mechanical attrition by fragmentation and abrasion. With the aid of three fitted constants, the model fitted the experimental results well.

Text

2020-08-14

Attribution 4.0 International

http://hdl.handle.net/2429/75555

Chemical and Biological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by/4.0/