Recalcitrance of gas hydrate crystals formed in the presence of kinetic hydrate inhibitors

Sharifi, Hassan; Ripmeester, John A.; Englezos, Peter

doi:10.1016/j.jngse.2016.03.035

Cited by 19 publications

(14 citation statements)

References 22 publications

(32 reference statements)

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“…These results are comparable with those reported previously [14]. Sharifi et al [47], Daraboina et al [48,49] and Makogon et al [50] have reported that hydrate formed in the presence of KHIs dissociated at a higher temperature compared to the hydrate prepared in pure water. Although PVP was found to inhibit hydrate growth it also seemed to stabilize the hydrate, and as a result it inhibits hydrate dissociation.…”

Section: Water + Ch 4 + Meg (W Meg = 10%)supporting

confidence: 92%

A 3-In-1 Approach to Evaluate Gas Hydrate Inhibitors

2019

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With a single apparatus and very short experimentation times, we have assessed phase equilibria, apparent kinetics and morphology of methane gas hydrates in the presence of thermodynamic inhibitors ethane-1,2-diol (MEG) and sodium chloride (NaCl); and kinetic hydrate inhibitor polyvinyl-pyrrolidone (PVP). Tight, local temperature control produced highly repeatable crystal morphologies in constant temperature systems and in systems subject to fixed temperature gradients. Hydrate-Liquid-Vapor (HLV) equilibrium points were obtained with minimal temperature and pressure uncertainties (u T avg = 0.13 K and u p = 0.005 MPa). By applying a temperature gradient during hydrate formation, it was possible to study multiple subcoolings with a single experiment. Hydrate growth velocities were determined both under temperature gradients and under constant temperature growth. It was found that both NaCl and MEG act as kinetic inhibitors at the studied concentrations. Finally, insights on the mechanism of action of classical inhibitors are presented.

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Section: Water + Ch 4 + Meg (W Meg = 10%)supporting

confidence: 92%

A 3-In-1 Approach to Evaluate Gas Hydrate Inhibitors

2019

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“…The hydrate decomposition recalcintrance was not observed under experimental conditions. Some researchers reported the KHIs can delay hydrate decomposition in their studies (Sharifi et al, 2014;Sharifi et al, 2016;Gulbrandsen and Svartås, 2017a,b). Sharifi et al (2014) investigated the decomposition of natural gas hydrate (CH 4 93 mol%+C 2 H 6 5 mol%+C 3 H 8 2 mol%) in the presence of PVP (3.5 kDa) or PVCap (23.3 kDa) with stirred vessels and DSC apparatus.…”

Section: Ch 4 Hydrate Decompositionmentioning

confidence: 99%

“…They believed that both sI and sII hydrtate formed in the presence of PVP and PVCap, then proposed a two-step decomposition mechanism. Subsequently, Sharifi et al (2016) tested the impact of three KHIs (PVCap, AFP III and Luvicap Bio) on C 3 H 8 hydrate decomposition with DSC apparatus. They found these KHIs has recalcitrance property for hydrate decomposition, and believed this property was not caused by the hydrate composition.…”

Section: Ch 4 Hydrate Decompositionmentioning

confidence: 99%

Inhibition of methane hydrate nucleation and growth by an antifreeze protein

Ramløv

Søgaard³

et al. 2019

Journal of Petroleum Science and Engineering

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…Englezos et al investigated the performance of KHIs by adding promotors, 10−12 and also investigated whether the KHI performance may change in NaCl and n-heptane solutions, 13,14 where an accelerated hydrate crystal growth was observed due to the presence of KHIs. 15,16 addition of an impurity can exert a kinetic hydrate inhibitor and its synergistic effect. 17−19 MEG as a hydrate inhibitor can be combined with the pH increase (pH stabilization) to act as a corrosion control for carbon steel pipelines.…”

Section: Introductionmentioning

confidence: 99%

“…Luvicap is a water-soluble polymer consisting of a hydrophobic backbone with pendant groups, which can interfere with the nucleation sites of the growing hydrate crystals. Englezos et al investigated the performance of KHIs by adding promotors, − and also investigated whether the KHI performance may change in NaCl and n -heptane solutions, , where an accelerated hydrate crystal growth was observed due to the presence of KHIs. , von Solms et al showed that the addition of an impurity can exert a kinetic hydrate inhibitor and its synergistic effect. − …”

Section: Introductionmentioning

confidence: 99%

Exacerbation of Hydrate Agglomeration in the Presence of Kinetic Hydrate Inhibitor under High pH Conditions

et al. 2021

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The performance of Luvicap EG was investigated to verify the efficacy of mixing kinetic hydrate inhibitors (KHIs) and monoethylene glycol (MEG) while varying the pH conditions in an aqueous phase. The relative torque changes were relatively stable in an early stage of hydrate formation; however, they started to increase and showed fluctuation when the hydrate fraction was larger than the transition value. Interestingly, the transition value was smaller for the base solution, suggesting that the efficacy of Luvicap deteriorated at high pH conditions. MEG was added to the Luvicap solution to confirm its synergistic effect at low and high pH conditions. The addition of MEG effectively slowed down the growth rate and the relative torques for the acid and the neutral solutions. However, for the base solution, dramatic changes in the growth rate were observed, followed by a severe fluctuation of the relative torque. Visual observation suggested that the catastrophic hydrate growth had occurred, and the formed hydrate particles were prone to deposit on the autoclave wall and to the impeller. Additional experiments varying the impeller speed indicated the occurrence of a thick hydrate film on the interface between the gas and the aqueous phases at a slow impeller speed, which increased the resistance-to-flow. Under all pH conditions, at 200 rpm, fluctuation of the relative torque was observed, and a high relative torque or severe fluctuation was observed at high pH conditions than in other pH conditions. It can be concluded that Luvicap EG would perform well under a high pH and a high impeller speed with an enhanced effect by the addition of MEG. However, a low pH and a low impeller speed would be the worst combination of exacerbating the agglomeration of hydrate particles, which would result in hydrate blockage.

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Recalcitrance of gas hydrate crystals formed in the presence of kinetic hydrate inhibitors

Cited by 19 publications

References 22 publications

A 3-In-1 Approach to Evaluate Gas Hydrate Inhibitors

A 3-In-1 Approach to Evaluate Gas Hydrate Inhibitors

Inhibition of methane hydrate nucleation and growth by an antifreeze protein

Exacerbation of Hydrate Agglomeration in the Presence of Kinetic Hydrate Inhibitor under High pH Conditions

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