CaMn sub(0.9)Mg sub(0.1)O sub( 3- delta ) as Oxygen Carrier in a Gas-Fired 10 kW sub(th)Chemical-Looping Combustion Unit

• Published in: Industrial & engineering chemistry research Vol. 52; no. 21; pp. 6923 - 6932-6923-6932
• Main Authors: Kaellen, Malin, Ryden, Magnus, Dueso, Cristina, Mattisson, Tobias, Lyngfelt, Anders
• Format: Journal Article
• Language: English
• Published: 29.05.2013
• Subjects: Carriers; Circulation; Combustion; Density; Fluidizing; Fuels; Natural gas; Reactors
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie303070h

Spray dried particles of the perovskite material CaMn sub(0.9)Mg sub(0.1)O sub(3- delta ) have been examined as oxygen carrier for chemical-looping combustion of natural gas. The experiments have been conducted in a continuously operating reactor with the nominal size 10 kW sub(th). The oxygen carrier particles showed excellent ability to convert fuel, and complete combustion was reached at certain conditions. In general, the CO sub(2) yield increased with increased fuel reactor temperature and with increased circulation rate. The oxygen carrier was able to release gaseous oxygen through the so-called CLOU-mechanism (chemical looping with oxygen uncoupling). When the fuel reactor was fluidized by inert gas, there was oxygen release at temperatures above 700 degree C, reaching a maximum of more than 3% for temperatures above 850 degree C. Gas phase oxygen was also measured during operation with fuel, as long as the fuel conversion was complete. When the fuel reactor temperature was above 900 degree C and a high enough circulation rate was maintained, complete combustion of the fuel was achieved with an oxygen concentration in the outlet stream from the fuel reactor of more than 1%. This suggests that a substantial part of the fuel is converted by gaseous oxygen released from the particles. The oxygen carrier particles were subject to more than 350 h of fluidization, of which more than 175 h was at high temperature and more than 55 h with addition of fuel. The particles did not show any tendencies to form hard agglomerations or break down to fines due to attrition during the experiments. Operational problems included high rate of particle elutriation, which was likely an effect of a mismatch between the size and density of the particles, the air flow, and the cyclone.