Understanding particle adhesion in CaCO3–CaO powder at high temperatures

Handling of particulate looping materials at high temperatures (500–800 °C) is important for the effective operation of chemical looping. Particles can exhibit high adhesion at high temperatures, which can lead to operational problems in chemical looping. Herein, particle adhesion in CaCO₃–CaO, a looping material, was carefully investigated at 500–800 °C. Particle adhesion in CaCO₃ increased with increasing temperature and retention time under most of the investigated conditions. The increase in tensile strength was attributed to weak sintering of CaCO₃. However, the tensile strength decreased with increasing retention time at 800 °C. This phenomenon was specific to 800 °C, where decarboxylation progressed rapidly. The CO₂ gas generated by decarboxylation formed voids in the powder bed, which increased the porosity of the powder bed, resulting in a decrease in the tensile strength. In addition, gas release via decarboxylation broke the weak sintered structure, resulting in a brittle powder bed.