The ethylene plant is on the west side of the site and includes seven reaction furnaces with their associated chimneys, plus its own fractionation columns.

The remaining natural gas liquids are piped south via a 223 kilometres (139 mi) pipeline to the Mossmorran site in Fife.

At the Fife NGL plant natural gas liquid is separated into its component parts by distillation in three sequential fractionation columns.

These comprise a de-ethaniser, a de-propaniser and a de-butaniser, the constituent components and products from the plant are: ethane (C2H6), propane (C3H8), butane (C4H10) and pentane (C5H12) or natural gasoline.

[4][6] The ethane is piped to an adjacent ethylene (ethene) cracker plant operated by ExxonMobil for processing and cracking.

These liquids are then transported as required via pipeline to the marine terminal at Braefoot Bay on the Firth of Forth for loading onto ships for export.

[6] The NGL plant originally operated using two identical process modules (each with three columns) with a capacity of approximately 10,000 tonnes per day.

The ethylene mixture is then cooled to 25°C in a series of heat exchangers and finally routed to a quench tower where water cascades down through the gas to remove by-products such as tar.

[8] A mixture called C5+ (compounds containing five or more carbon atoms) is removed from the bottom of the de-ethaniser and is used as a feedstock in the chemicals industry.

[13] In 2020, a study conducted by scientists in China found that living near a petrochemical plant can cause higher cases of major depressive disorders.

Professor Andrew Watterson of Stirling University has revealed that environmental pollution, such as sound and light, can affect the mental health of locals surrounding these plants.