“磷酸预浓缩法”磷铵节能新工艺及关键技术

Energy saving process and technology for ammonium phosphate production by phosphoric acid pre-concentration

首次提出免用生蒸汽的"磷酸预浓缩法"磷铵节能新工艺,以约130℃下氨与磷酸中和反应为内热源的磷酸三效逆流蒸发,末效蒸发温度约55℃,总蒸发量751.8 kg/t(产品),中和料浆含水质量分数25%,满足湿法磷酸制磷铵的工艺要求。作为关键技术,尾气余热低温磷酸喷射降膜浓缩和大型装置开发成功并运用于磷酸二铵(DAP)联产磷酸一铵(MAP)工艺,使DAP反应造粒尾气排放湿含量下降50%,MAP节约蒸汽5万t/a。运用该技术改造24万t/a料浆浓缩法MAP装置,实现了蒸汽消耗降低30%、浓缩废气减排30%、产能提高50%,节能减排效益与经济效益同步增长,具有广泛推广应用的价值。

A novel energy saving process, characterized by the phosphoric acid pre-concentration （PAPC）, is proposed firstly for ammonium phosphate production without any external steam supply. With the internal heat source of chemical reaction of NH3 and H3PO4 under the temperature about 130℃, the evaporation ability of the phosphoric acid pre-concentration system, consisting of countercurrent flow and triple-effect evaporators with the end evaporation temperature of 55℃, can reach the amount of 751.8 kg （H2O）/t of MAP. It fairly meets the concentration task required by the processes of MAP production from wet-process phosphoric acid. As the key technology, a large-scale equipment of jetting and falling film evaporator is thus developed and successfully applied to the integrated production line of DAP and MAP, making a 50% reduction of tail gas humidity for DAP and saving 50 000 t/a of steam for MAP. Another successful application is made to enhance the capacity and reduce waste gas and energy consumption for a 240 kt/a MAP production line by the process of slurry concentration.As a result its output increases by 50%, meanwhile both the steam consumption and exhaust tail gas decreases by 30%.