True biodegradable green KHIs (under Norwegian patent 327578, 2009)
One of these products is a biodegradable, low toxicity, water-soluble pseudo-protein based polymer in an environmentally-friendly blend of 2 solvents (both allowed off-shore Norway). The product prevents hydrate formation at up to 8 ºC subcooling in water-gas or water-oil-gas systems. The Polymer is Yellow 1 category in Norway.The active polymer content is approximately 35 – 40 weight-%. The product appears as a pale brown liquid. The long-term stability is 1 year+. The manufacturing method is patented separately by the chemical company who has developed the KHI product together with Eco Inhibitors.
The other biodegradable KHI product is available as 30 – 40% active ingredients in water/MEG and appears as an almost colourless solution. Tests conducted in 10 isothermal rocking cell tests at 36 bar and 7 ºC sub-cooling in DI water/condensate (water cut 30 %), resulted in no hydrates for two weeks. Two further weeks at 8 ºC sub-cooling gave a very small amount of hydrate formation, but no plug or rapid hydrate formation. Volumes of 70+ tons/year are expected to be available from early 2016. Much larger quantities can be made available on request. This KHI is biostabilised in MEG with which it is totally compatible. i.e. the product could be used stand-alone or in blends with thermodynamic inhibitors (MEG or alcohols). The product has a long shelf-life. No degradation or bacterial growth was observed after 9 months at 25 ºC when testing was stopped. The KHI shows good thermal stability up to 160 ºC in MEG or MEG/water without loss of performance in subsequent tests. It is low foaming (as observed during KHI sapphire cell rocker rig tests) and low viscosity for easy injection in cold climate. No emulsion problems have been observed, although only a few oils have so far been investigated. It is environmentally-acceptable as it is a natural product with no chemicals added apart from MEG.