Study on thermodynamics of fixating sulfur during coal combustion

This paper analyses thermodynamics and SO2 equation consistency of reaction of sulfur fixation. The cheap fixating sulfur agent is commonly oxide or carbonate containing calcium, for example lime or limestone and so on. When the temperature is 1400 K (1127°C), the quantity of absorbing heat for limestone being decomposed is 165.96 kJ·mol^-1, and the quantity of out heat for the lime (CaO) fixation sulfur is 467.49 kJ·mol^-1. If the utilization ratio of fixating sulfur agent (limestone CaCO3) is about 30%, the heat output of fixation sulfur is almost equal to the absorption of heat when limestone is decomposed, and out heat of mixture of coal and fixation sulfur agent is not affected. By calculating and deducing, the free energy of the fixation sulfur reaction is negative, and the SO2 equation consistencies are much lower than practical SO2 consistency in boiler chamber, therefore positive direction impetus of the fixation sulfur reaction is very big. When sulfur contents in coal are 2.28% and 4.22%, the out heats of the mixture of coal and fixation sulfur agent are tested. Practical tests show that combustion of coal in presence of suitable fixating sulfur agents not only runs without harmful effect, but also raises total heat output in some cases.