Desulfurization method and system for co-production of active calcium or gypsum by combining ammonia and calcium with regenerated ammonia water

The invention discloses a desulfurization method and system for co-producing active calcium or gypsum by combining ammonia and calcium with regenerated ammonia water, and relates to the technical field of atmosphere control. Ammonia-process first-stage incomplete desulfurization is matched with calcium hydroxide dry-process second-stage complete desulfurization, and around regeneration and conversion of two-stage desulfurization products, a relatively pure ammonium bisulfate solution reacts with calcium sulfate containing excessive calcium hydroxide, and a relatively pure ammonium bisulfate solution reacts with calcium sulfate containing insufficient calcium hydroxide; and correspondingly regenerating ammonia water and precipitating calcium sulfate containing calcium hydroxide, carbonizing and drying the ammonia water containing ammonium bisulfate and precipitating calcium sulfate to obtain an active calcium product with high added value and large market demand, and drying the latter to obtain a high-purity g