磷铵尾气减排与节能的过程分析与实验

Process analysis and experiment on tail gas reduction and energy saving for ammonium phosphate production

分析了60万吨/年磷酸二铵(DAP)生产装置尾气形成"磷铵雨"的热力学机理,提出尾气部分冷凝-磷酸降膜蒸发过程耦合技术,现场实验证明了该技术的可行性,现场实验获得的P2O5质量分数27.1%～41.7%范围内磷酸蒸发浓缩数据,该工艺使尾气湿含量减少至0.065kgH2O/kgair。研究了磷酸液膜雷诺数以及磷酸液膜过冷度对磷酸降膜蒸发过程的影响,揭示了在55℃以下低温浓缩湿法磷酸的可能性。这对磷酸浓缩技术很有参考价值。

Thermodynamic analysis of ammonium phosphate polluted droplets formation in the tail gas discharged from a 600 （kt/a） diammonium phosphate （DAP） production line was made. A unique technique was developed to make a full use of the limited driving force for heat transfer by integrating the processes of partial condensation of tail gas with falling film evaporation of raw phosphoric acid. The feasibility was demonstrated by the pilot experiments. Phosphate acid concentration （P2O5%） was in the range of 21.1%-41.7% and water content in the tail gas was reduced to below 0.065 kg H2O/（kg air）o The influence of phosphate acid falling film Re and subcooling fall film on evaporation of phosphate acid falling film was studied by spot experiment. It displayed the possibility of phosphoric acid concentration at a temperature below 55 ℃. The experimental results were valuable for phosphoric acid concentration.