To avoid corrosion in NHT Stripper overhead circuit, what should be range of PH in overhead receiver boot? and what should be the temp of overhead condensing stream to receiver at around 10.5ksc press?
Answers
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01/03/2011
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Celso Pajaro, Sulzer Chemtech, celso.pajaro@sulzer.com
Corrosion in the stripper overhead can be due to HCl coming with the hydrogen, in this case pH in the overhead should be kept between 4.5 and 6.5, other possibility is the formation of amonium chloride salts which will produce under deposit corrosion, for this case water wash is recommended either at the column overhead, and/or at the surge drum located upstream of the stripper. Water wash will take most of the HCl, and ammonia out.
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28/02/2011
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Alan Goelzer, Jacobs Consultancy, alan.goelzer@jacobs.com
More information is needed in order to address this, i.e.
# What are typical or average 'S' & 'N' & 'O' and Bromine Number in the fresh feed ?
# Any insights or measurements of 'Cl' and other trace hetero-atoms in fresh feed ?
# What is NHTU RxP,inlet pressure and typical RxT,outlet temperature ?
# Is water washing occasional or continuous ahead of REAC air cooler ?
# Is stripped sour water being used as part of wash water ?
# What is being used to reboil the NHTU Product Stripper ?
# Is the overhead condenser an air cooler or water cooler ?
# Is the overhead condenser 'submerged' [lower than reflux drum]?
# How often is sour water being decanted from reflux drum ?
# Is 'artificial oil dewpointing' practiced [recycling some reflux to injector at condenser inlet] ?
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