Design and Mitigation Techniques for Applications with Possible Liquid Contamination of the Sealing Gas Dry Gas Seal System

Abstract

A compressor in a natural gas gathering service experienced multiple seal failures on the discharge end. Synthetic oil mist contained in the sealing gas was identified as a significant source of contamination that caused the seal failures. Since similar dry gas seals in other compressors at the same location were operating satisfactorily, a study of a particular compressor was undertaken. The seals were instrumented with thermocouples to monitor the temperature distribution across the seals. This paper discusses the findings of the study, resulting modifications of the dry gas seals, seal controls, and the compressor itself. This paper also outlines techniques that have been developed to mitigate the situation without having to shut the unit down. Also presented is a design approach to the sealing and seal monitoring in processes where liquid ingress into the sealing area may occur, including seal material selection, control system philosophy, seal head, and bearing cavity design.