High pressure urea stripper is a falling film shell and tube heat exchanger that recovers more than 60% of the unconverted reactants.Historically,this exchanger has been demanding constant attention of the user,manufacturer and designer due to its nature of service in adverse condition comprising of high temperature,high pressure,corrosive medium and presence of dual phase of liquid and gas.The technology of bimetallic stripper introduced by Snamprogetti has proved to be a successful alternative of Titanium stripper because of its resistance to both corrosion and erosion.This paper shares the experiences of old and new generation bimetallic strippers at IFFCO Phulpur Unit-ll and Unit-l,respectively.The old design bimetallic strippers at Unit-ll have been running successfully,whereas severe corrosion was experienced inside the bottom channel of the new design bimetallic stripper at Unit-l within six months of commissioning.The exchanger was repaired in-house and continuous air injection has been ensured at the bottom channel.
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