2011 10 Idris Anwer Engro UreaKnowHow.com Urea Stripper Leakage Identification & Rectification
This paper entails the chronic problem of Fertilizer Industry regarding leakage in Urea Stripper. The intent of this article is to highlight the issues faced in identification of Urea Stripper leakage during plant operation without taking stripper out of service and then to rectify the leakage. It is a million dollar decision when to take Stripper out of service for leakage rectification.
Function of Urea Stripper is to decompose unconverted Carbamate into Carbondioxide and ammonia increasing Urea solution concentration. Usually heat required to decompose Carbamate is transferred from steam which is on the shell side and Urea solution on the tube side. It acts as a falling film evaporator. Due to Urea solution on tube side, the metallurgy of tubes, channel heads and tubesheet is the area of concern requiring material having super corrosion resistance. Normally, tubes are in Titanium, Duplex Stainless Steels, Zirconium or Bimetallic. Tubesheets and channel head covers are cladded or weld overlaid with corrosion resistant materials in order to save cost.