As Green As It Gets: An Abundant Kinetic Hydrate Inhibitor from Nature

摘要

We report the development of a kinetic hydrate inhibitor (KHI) based on a cheap, abundantly available natural product that is readily biodegradable and low in toxicity. The optimal product, called KHI530, was determined using KHI screening tests by the slow constant cooling method in multiple rocking cells. The performance was better than a low molecular weight poly(N-vinylpyrrolidone) for a synthetic natural gas mixture (SNG) forming primarily structure II hydrate and about the same performance for structure I methane hydrate. Isothermal tests using the SNG mixture indicate that an active dosage of 0.5 wt % can protect against hydrate formation for 48 h at a subcooling of 6-7 degrees C. KHI530 exhibits no cloud point up to 95 degrees C in deionized water or NaCl brines up to 7 wt %. KHI530 can be biostabilized in monoethylene glycol (MEG) or using a biocide such as tetrahydroxymethylphosphonium sulfate (THPS), which does not affect the KHI performance. KHI530 was found to be fully compatible at all ratios with thermodynamic hydrate inhibitors (THIs) such as methanol or MEG and survived thermal treatment to 160 degrees C in aqueous MEG solutions for 1 h with no loss of KHI performance. Blends of KHI530 with MEG at various ratios were examined for KHI performance and shown to have good additive effect. The product is therefore useful as a stand-alone KFII for low subcooling applications or can be used to replace or reduce the amount of thermodynamic hydrate inhibitor (THI) where the THI pumping capacity has been reached.