The development of a 500 g macro-thermogravimetric analyzer and its typical application in the thermal decomposition of limestone

This work developed a macro-thermogravimetric analyzer (macro-TGA) of maximal 500 g sample capacity as the mini-pilot system to evaluate the thermochemistry process for industrial bulk samples, which is the first report about the lever-equal beam balance-based wide-range/variations (500 g) macro-TGA with high precision, excellent reliability and low cost. The macro-TGA adopts many novel designs to become one of the most advanced macro-TGA, including eight groups of reinforced parallel coils and magnetic cores as the electronic mass with enough force moment weighing 500 g mass, elaborately arranged blast fences and gas distribution tube with minimum disturbance from gas flow, as well as a all-sided ventilated ceramic crucible coupling a mobile thermocouple with minimal influence of mass/heat transfer from apparatus itself. As a typical application case, the thermal decomposition behaviors and apparent kinetics of industrial bulk limestone were evaluated by this macro-TGA. Compared with results from micro-TGA, the industrial bulk limestone in macro-TGA exhibits completely different thermal decomposition behaviors with obviously elevated initial thermal decomposition temperature, significantly prolonged thermal decomposition time as well as different apparent activation energies, which can be attributed to significant differences between bulk and fine limestone particles in terms of heat transfer resistance and inherent structure. The demonstrated wide-range/variations lever-equal beam balance-based macro-TGA with good reliability will become a powerful mini-pilot instrument to evaluate the thermal decomposition behaviors and apparent kinetics of industrial bulk samples with large mass/size.