Problem No. 7: Urea melt pump damage

The urea melt pump is a challenging application of a centrifugal type of pump: On the discharge side it has a relatively high pressure as the urea melt needs to be pumped up to the top of the prilling tower, which is typically some 100 metres high; while on the suction side vacuum pressure exists. Furthermore, the urea melt needs to be pumped with a minimum residence time to minimise biuret formation, so the residence time at the suction is limited. Finally the urea melt can easily crystallise transforming into biuret, triuret or further poly-urea products, which can cause cavitation and damage the pump.