Abstract
Corrosion and fouling above the water dewpoint has been reported in many crude unit overheads and on the upper trays of crude towers. Field studies were conducted which show that these problems are commonly caused by deposition of amine and/or ammonia hydrochloride salts. Since these salts can deposit only if their equilibrium vapor pressures are exceeded, salt volatility is a major criterion of neutralizer selection. A survey of the literature indicates that amine salt volatility has not been considered in a quantitative manner until now.
Knudsen effusion measurements have been used to determine equilibrium vapor pressure functions for the hydrochloride salts of five commonly applied neutralizers and ammonia. A spreadsheet was developed to utilize these vapor pressure functions along with crude unit operating conditions to predict salt dewpoints in crude units. To address the needs of crude units where salt deposition is not avoidable with traditional neutralizers, a research program was conducted to develop new neutralizers which form more volatile hydrochloride salts. Case histories are presented which discuss results of field trials with traditional and novel neutralizers.
