HCl and SO_2 Simultaneous Absorption at 1023 K with Calcined Limestone

摘要

In order to understand sorbent performance for co-combustion of coal and wastes such as refused derived fuel, simultaneous absorption of HCl and SO_2 with calcined limestone was fundamentally investigated using a thermogravimetry at 1023 K. SO_2 absorption was interestingly accelerated in the presence of HCl and the level of conversion of calcined limestone reached almost 100percent even when particles with 710-1000 mum of diameter were used. The mechanisms of this increase in absorption capacity were discussed mainly based on the results of scanning electron microscopic and energy dispersive analysis of X-ray observations, and differential scanning calorimetry. As a result, it was concluded that a molten phase was formed on limestone surface in the early stage of reaction and this phase spreaded into the bulk with the progress of reaction. Melting point was lowered to ca. 998 K by formation of an eutectic phase of CaSO_4 and CaCl_2 mixture. It was considered that such amolten phase causeed the absorption capacity increase observed for simultaneous absorption of HCl and SO_2 with calcined limestone.