NEW INLET FEED GAS CONDITIONING TECHNOLOGY FOR CONTAMINANT REMOVAL IN AMINE UNITS

摘要

Amine solvent foaming is a common problem in gas treating plants, including those ahead of LNG manufacturing facilities. This can lead to reduced gas throughput, and in severe cases, solvent carryover and perhaps even plant shutdown. This foaming is ultimately caused by changes in physical and chemical properties of the solvent. Chemical contaminants can lower amine solution surface tension and change surface rheology in such a way that foaming tendency is augmented and foam is stabilized. Earlier work has shown that these contaminants are not restricted to liquid hydrocarbons, but can be from a variety of other possible sources. While some of the contaminants may originate from within the amine unit itself, many are introduced with the gas, such as upstream production chemicals and produced water. While antifoam products can temporarily alleviate a foaming episode, they can also be a detriment and build up over time, fouling vessels and internals.Some LNG plants employ inlet coalescers, filters or a water wash to remove contaminants in the feed gas. However, these systems may not be completely effective for the removal of certain contaminants. Furthermore, the vessels or water demands of these wash systems can be large and relatively inefficient. This paper describes a new technology to prevent the introduction of contaminants into amine units. The novel system is installed in-line with the feed gas pipe, and is comprised of a compact water-wash device capable of removing water soluble components such as surfactants and salts from incoming feed gas. The spent water can be treated and recycled to minimize water make-up and clean water consumption.