Liquid, Hydrates and Foam Detection Improves Operational Excellence in Gas Treatment

Before natural gas can be transported, acid gases (CO2 and H2S) have to be removed, as well as any liquids that could condense in the pipeline. Gas/liquid separation is required both upstream and downstream of gas treatment plants. The separator performance is one of the most common causes of problems and capacity constraints. Foaming, flow surges, start-up, shutdown, and flow ramping are all common causes of liquid and foam carry-over. Liquids in a gas network collect at low points where they cause corrosion or are swept out as a slug of liquid that can damage sensitive equipment downstream. Undetected liquids cost the industry $millions every year in damage, lost revenue and labour costs. This paper describes the 9-year development of a new permanently installed camera-based monitoring system, operating at high-pressure, that can improve operational excellence by providing a continuous live video stream of pipeline activity. Using image processing, an alarm can be activated if liquids, hydrates or foam are detected at very low levels. This improves operational decisions that lead to lower downtime, higher process safety and increased production. By installing the system at custody transfer points, accountability can also be improved. Gas analysis systems, normally installed at custody transfer, are designed to avoid and remove liquids, allowing liquid contaminants to pass without triggering an alarm. There have been many instances of contamination events causing significant damage to compressors, gas turbines or even pipeline ruptures. Now, separator and knock-out pots can be monitored leading to significantly lower levels of liquid contamination in tie-backs and gas networks leading to optimisation of costly pigging or reverse flow cleaning processes.