D4.5 Guidelines on raw meal characterization for CaL applications


Based on a comprehensive assessment the of influence of the sorbent’s CO2 carrying capacity presented a guideline for raw meal characterisation with respect to their calcium looping properties is developed in this deliverable.
Overall the carbonation performance of raw meal based sorbent is in agreement with those reported for limestone based sorbents commonly employed for calcium looping purposes. With increasing CO2 partial pressure the carbonation reaction accelerated while the CO2 carrying capacity was not affected. Humid carbonation conditions increased the sorbents’ CO2 carrying capacity. However, raw meal based sorbents suffer a more severe deactivation during calcination associated with silicate formation compared to limestone based sorbents. By reducing the calcination time the sorbent deactivation can be limited and a higher CO2 carrying capacity is yielded. The extent of sorbent deactivation depends on the raw meal origin or its composition. Conditions that favour calcination appear to enhance belite formation and therefore reduce the sorbent’s CO2 carrying capacity, especially for marlish sorbents.
For short calcination times in the range of a few minutes the raw meal’s carbonation performance appears to be superimposed by the individual performance of the raw meal’s components. The experiments with a reduced calcination time are in adequate agreement with the results of the entrained flow experiments presented in Deliverable 4.4.
The results indicate that TGA analysis offers an easy way to assess the CO2 carrying capacity of raw meal based sorbents. The results further highlight that the assessment should be carried out at operation conditions representative for the actual process. For an entrained flow calcium looping system that means rapid heat-up rates and short calcination times.