Petrochemical solutions producers Chemflo is providing chemical compatibility and separation solutions for challenges arising from new technology and innovations in the petrochemical industry.

Three of the new technology and innovation trends that has impacted on cartridge filter use and coalescer separation processes are; low sulphur diesel, alkylation, and the increasing use of methyldiethanolamine (MDEA) for amine sweetening.

A coalescer is a technological device performing coalescence, which is the fusion or blending of parts, in this case a liquid contaminant from a liquid process fluid.

Low Sulphur diesel

Chemflo manufactures filter elements and coalescer cartridges specifically for ultra low sulphur diesel (ULSD) systems. Products include coalescers that perform at lower interfacial tensions, and high capacity filter medias, that withstand the more rigorous chemical compatibility issues owing to the increased solvent nature of ULSD.

Diesel refiners in several parts of the world, and particularly in the US and Europe, have made huge investments to lower the sulphur content in diesel. Most systems use ULSD hydrotreaters to reduce sulphur content. Typically, sulphur content is 10 particles per million (ppm) in much of the EU and 15 ppm in the US. Several other countries, including South Africa, are moving towards low sulphur ppm standards as well.

ULSD requires good separations of solids and liquids to prevent channeling and to protect catalysts. In ULSD, gaskets, seals and filters need to be upgraded because of leakage, owing to feed product that flows through the system. ULSD is a powerful solvent and attacks several elastomers, cellulose, filter binders and several polymers used in production of the more commonly available filter and coalescer cartridges.

ULSD often has low interfacial tensions (IFTs), which is the resistance present at the surface of two unlike substances such as oil and water. Interfacial tensions may range from as low as 10 dynes/cm to 15 dynes/cm in many cases. Interfacial tensions substantially affect the way coalescers operate. Many coalescers do not perform well in ULSD, unless the polymers and elements are specifically designed for low IFT applications.


Several polymers, binders and adhesives used in cartridge filters and coalescers suffer chemical attack in alkylate. Chemflo has designed Duraflo filter cartridges and liquid-liquid coalescers to provide enhanced service and contaminant capacity for both lower and moderate temperature alkylate.

There has been substantial improvements in alkylation over the past 10 years, including processes from supplier and licensor of process technology UOP, engineering companies ABB/Lummus, catalyst and technology company Haldar Topsoe, and engineering and research company Lurgi. Alkylation systems allow refineries to produce a high-octane gasoline component called alkylate through the alkylation of isobutene and butane. Hydrofluoric or sulphuric acid is used as a catalyst in these type of systems. The combination of acid carryover and isobutylene is a very aggressive solvent and dissolves many common filter materials.

Chemflo manufactures filters and coalescers compatible with both isobutylene and low pH associated with catalyst carryover.


Another significant technology trend in the petrochemical industry is the increasing use of MDEA systems for natural gas sweetening, which is the reduction of the sulphur content of crude oil, at refineries. MDEA is a more expensive solvent than normal amines, but it has a better adsorptive capacity, selective absorption capability and slower degradation rates.

Chemflo manufactures amine filters that have increased efficiency for use with MDEAs. Chemflo filters operate at moderately higher temperatures, unlike conventional polypropylene filters, which cannot operate at high temperatures. The company manufactures a rich amine filter called the Amine Depthflo filter, which is designed to remove long chain hydrocarbons and iron sulfides.

Amine systems sweeten natural gas and often remove carbon dioxide, making it an environment friendly process. Since this is a closed loop system, contaminants build up over time. Iron sulphides with a small particle size distribution cause significant operating problems in the large amine systems at refineries. Operating problems include, having to run amine at higher amine to water concentrations, amine losses, and system fouling or upsets.

MDEA is more expensive than the amines, diethanolamine and tetraethylammonium, and the costs associated with amine losses and expenses, because of the need to run a higher percentage amine, can be very expensive. Additionally, because MDEA is designed to run longer than other ethanolamines, proper care of the amine is more important to prevent fouling the amine. By applying separations technologies, including 100% filtration provided by Chemflo filters, and its 10 µm absolute or tighter efficiency filters, substantial reductions in upsets, amine losses and amine concentrations are achieved.