Kinetic study of the reaction between sulfur dioxide and calcium hydroxideat low temperature in a fixed-bed reactor

A quantitative study of the influence of inlet sulfur dioxide concentration (600-3000 ppm), relative humidity (20-60%), reactor temperature (56-86 deg rees C) and different amounts (0-30 wt.%) of inorganic additives (NaCl, CaC l2 and NaOH) on gas desulfurization has been carried out in a continuous do wnflow fixed-bed reactor containing calcium hydroxide diluted with silica s and. Results show that the reaction rate does not depend on sulfur dioxide partial pressure (zero-order kinetics) and that the temperature and the rel ative humidity have a positive influence on reaction rate. An apparent acti vation energy of 32 kJ/mol Ca(OH)(2) has been estimated for the reaction. An empirical reaction rate equation at 71.5 degrees C and 36.7% relative hu midity that includes the type and amount of additive is proposed. It has be en found that calcium chloride is the best additive studied because it allo ws for a higher degree of sulfur dioxide removal. (C) 2000 Elsevier Science B.V. All lights reserved.