Experimental investigation on the direct limestone-H2S reaction in a pressurized thermogravimetric analyzer

Sulfidation experiments with Chinese limestones were performed in a pressurized thermogravimetric analyzer (PTGA) under noncalcining conditions. The effects of total pressure (0.1-1.5 MPa), reaction temperature (700-950 degrees C), H2S molar fraction (0.1%-5.0%) on the sorbent conversions were analyzed. Experimental results show that the sulfidation of fully calcined limestone is much faster than the reaction of noncalcined limestone. The sulfidation rate increases with total pressure when the volume fraction of H2S is Constant. However, the rate of sulfidation decreases with the increase of total pressure when the H2S partial pressure is constant. Reaction temperature affects the sulfidation greatly, the initial reaction rate increases with temperature. However, it is not necessary to obtain the high final conversion at high temperatures. At higher temperature, the sintering of sample is more serious resulting in the decrease in the sulfidation rate. The sulfidation is the first order with respect to H2S partial pressure for the limestone.