磷酸二铵颜色发黄原因分析及解决措施

270kt／a磷铵装置用同一种磷酸生产磷酸二铵时，产品颜色由果绿变为黄色。分析其产品颜色变化原因，采取对造粒机管式反应器、二次氨化、返料破碎机的改造措施，减少造粒机氨逸出量，降低中间槽、预洗涤器洗涤液中和度，控制中间槽洗液pH值在2．7以下。改造后洗液和产品颜色稳定在果绿色。

Analysis on factors affecting the color turning to yellow of DAP and solving measures

With the same phosphoric acid, the color of DAP in 270 kt/a plant turns to yellow from fruit-green color. The cause of color change is analyzed. Some reforming measures are taken in granulator tubular reactor, two stages ammoniation machine and return product crusher to reduce the escape of ammonia, decrease neutralization degree of washing liquid in intermediate tank and per-scrubber, control the pH less than 2.7. After the reform, washing liquid and product are stable.