FLUE-GAS DESULFURIZATION

摘要

PURPOSE: To improve the utilization factor of a desulfurizing agent and separation and recovery of crystalline gypsum by converting dissolved calcium ion existing in a slight amount in a circulating liquid into calcium sulfite and then separating a slurry of fine particles of magnesium hydroxide and a slurry of coarse particles of gypsum dihydrate and calcium sulfite. CONSTITUTION: A treated liquid in a desulfurizing process is supplied to a first oxidizing tank 2 from a desulfurization tower 1 and oxidized by air to form an aqueous solution of magnesium sulfate and sulfuric acid. The aqueous solution of these substances is supplied to a double decomposition tank 3 and further mixed with an aqueous solution of magnesium sulfate separated and supplied from a precipitation tank 8 and with a water slurry of calcium hydroxide from a supply tank 4 to produce solid particles of gypsum dihydrate and magnesium hydroxide. The water slurry containing these two types of solid particles is then led to a calcium ion conversion tank 5 and calcium sulfite insoluble in water is produced and precipitated. Next, the water slurry containing these substances is separated into a fine particle slurry and a coarse particle slurry in a wet type classifier 6.