CLOU process performance with a Cu-Mn oxygen carrier in the combustion of different types of coal with CO2 capture

Abstract

The Chemical Looping with Oxygen Uncoupling (CLOU) process is a Chemical Looping Combustion (CLC) technology that allows the combustion of solid fuels with inherent CO2 separation by using oxygen carriers based on metal oxides. This technology has low energy penalty and thus low CO2 capture costs. In CLOU, the oxygen carrier must be able to release gaseous oxygen which limit the availability of metal oxides for this process. In this work, the suitability of oxygen carrier particles containing 34 wt.% CuO and 66 wt.% Mn3O4 (active phase Cu1.5Mn1.5O4) prepared by granulation was investigated in a continuous 1.5 kWth rig during CLOU combustion of different rank coals (two sub-bituminous and a lignite). The effect of the different coals in the combustion and CO2 capture efficiencies at different oxygen carrier to coal ratios was studied. It was found that full combustion can be reached independently of the coal used. However, CO2 capture efficiencies were highly determined by the coal rank. Finally it was found that work with oxygen carrier to coal ratios higher than 4 and the low oxygen carrier conversion both in the fuel and air reactors decreasing the effect of 1 the chemical stress in the attrition rate; therefore it is clearly beneficial for the lifetime of the oxygen carrier particles to operate with low ΔX between fuel and air reactors.

Chemical Looping Combustion of gaseous and solid fuels with manganese-iron mixed oxide as oxygen carrier

“…On evaluation of the operating conditions set for these tests, the different oxygen carrier to fuel ratio used is worthy of note. It has recently been suggested that a low oxygen carrier to fuel ratio, which is related to high variation in oxygen carrier conversion during redox cycles in a CLC unit, damages the mechanical integrity of the particles [42]. This is in agreement with the decrease in the mechanical strength of the particles in the experiments with coal, where the oxygen carrier to fuel ratio was  = 1-1.5.…”

“…In this sense, Pérez-Vega et al [38] after 45 h of operation. This oxygen carrier showed excellent performance in a CLOU unit burning coal, while the evolution of its mechanical properties depended on the solids circulation rate [42]. Thus, particles maintained high mechanical strength when the solids circulation rate was high enough to support an oxygen carrier to fuel ratio higher than 3-4.…”

Perovskites in the Energy Grid and CO2 Conversion: Current Context and Future Directions

“…Furthermore, an oxygen carrier consisting of CuO, Fe 2 O 3 , and MgAl 2 O 4 has been explored for chemical looping combustion applications [134]. Adanez-Rubio et al [135] discussed the applicability of CuO/Mn 3 O 4 as an oxygen carrier for chemical looping. The lifetime of this oxygen carrier was found to be significant for a large oxygen carrier/fuel ratio.…”

Comparative study of fuel-N and tar evolution in chemical looping combustion of biomass under both iG-CLC and CLOU modes

“…The oxygen carrier must have adequate oxygen equilibrium partial pressure at temperatures of interest for combustion (800-1200ºC) and also withstands long periods of continuous redox cycles. Up to date, only few materials have demonstrated their adequacy for the CLOU process [10][11][12], mostly based on copper oxides or perovskites. Thus, they are also expensive oxygen carriers when compared to those for iG-CLC.…”