Fouling and consequent underdeposit corrosion caused by ammonium salts, especially ammonium chloride, have serious impact on the reliability of operation of various process units. Fouling of tower trays can result in the loss of throughput, changes in the vapor pressure and endpoints of product streams, increased pressure drop in the tower, and corrosion of the trays. Salt deposition on heat exchanger tubes causes a decrease in heat transfer efficiency, increased pressure drops, and
corrosion. This paper will discuss the causes of ammonium chloride fouling, methods to help prevent and/or mitigate the fouling, and provide several case histories demonstrating the effects of using ammonium chloride dispersants to clean existing ammonium chloride deposits and to help prevent deposition of this salt.