High-resolution performance tests of nucleation and growth suppression by two kinetic hydrate inhibitors

Barwood, Mark T.J.; Metaxas, Peter J.; Lim, Vincent W.S.; Johns, Michael L.; Aman, Zachary M.; May, Eric F.

doi:10.1016/j.ces.2021.116776

Cited by 20 publications

(10 citation statements)

References 44 publications

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“…The kinetic nucleation parameter, A , is described by CNT as the product of the Zeldovich factor (0.01 < z < 1), the number of available heterogeneous nucleation sites, N 0 , and the frequency of monomer attachment to the growing nucleus, f The thermodynamic parameter, B′ , reflects the work required for nucleation on the active heterogeneous nucleation (HEN) sites. This parameter includes the volume of the solid-forming (hydrate) building unit, v , shape factor of the formed solid cluster, c , and the surface energy of the new solid–fluid interface, σ ef , at the HEN site To extract values of A and B′ from J (Δ T ) data, eq can be linearized: ,,, where Measured (Δ T , J ) data exhibiting a linear trend in the x – y coordinate system defined by eqs and are then characterized by a single pair of A and B ′ parameters. Figure b shows the nucleation rate data presented in Figure a using these linearized coordinates.…”

Section: Resultsmentioning

confidence: 99%

Aqueous Solid Formation Kinetics in High-Pressure Methane at Trace Water Concentrations

et al. 2023

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Natural gas containing trace amounts of water is frequently liquefied at conditions where aqueous solids are thermodynamically stable. However, no data are available to describe the kinetics of aqueous solid formation at these conditions. Here, we present experimental measurements of both solid formation kinetics and solid–fluid equilibrium for trace concentrations of (12 ± 0.7) ppm water in methane using a stirred, high-pressure apparatus and visual microscopy. Along isochoric pathways with cooling rates around 1 K·min–1, micron-scale aqueous solids were observed to form at subcoolings of (0.3–8.6) K, relative to an average equilibrium melting temperature of (253 ± 1.9) K at (8.9 ± 0.08) MPa; these data are consistent with predicted methane hydrate dissociation conditions within the uncertainty of both the experiment and model. The 36 measured formation events were used to construct a cumulative formation probability distribution, which was then fitted with a model from Classical Nucleation Theory, enabling the extraction of kinetic and thermodynamic nucleation parameters. While the resulting nucleation parameter values were comparable to those published for methane hydrate formation in bulk-water systems, the observed growth kinetics were distinctly different with only a small percentage of the water in the system converting into micron-scale solids over the experimental time scale. These results may help explain how cryogenic heat exchangers in liquefied natural gas facilities can operate for long periods without blockages forming despite being at very high subcoolings for aqueous solids.

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Section: Resultsmentioning

confidence: 99%

Aqueous Solid Formation Kinetics in High-Pressure Methane at Trace Water Concentrations

et al. 2023

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“…Because PVCap is a commercial and effective KHI, it is used to copolymerize with pyrrolidone macromonomers. Additional macromers such as acrylamido propanesulfonic acid and dimethyl aminoethyl methacrylate , have also been used to synthesize terpolymers with VP/VCap copolymers. These co/terpolymers are all commercial KHIs.…”

Section: Performance Of Pyrrolidone-based (Five-membered-ring Lactam)...mentioning

confidence: 99%

Review of Kinetic Hydrate Inhibitors Based on Cyclic Amides and Effect of Various Synergists

Singh

Suri

2021

Energy Fuels

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This Review presents a comprehensive literature review of an important class of kinetic hydrate inhibitors (KHIs) that is based on cyclic amides (lactams). The major aspects of the KHIs, such as their synthesis, inhibition mechanism, toxicity, biodegradability, performance, and cloud point, are thoroughly discussed. Data for 70 KHIs made of homo/co/terpolymers from 330 experiments are collected and evaluated for performance. The effects of the inhibitor concentration, molecular weight, monomer ratio of the co/terpolymers, and 35 different synergist chemicals on various KHIs are also studied. In conclusion, the top 10 KHIs with the highest performances that had a cloud point above 70 °C are presented. The copolymer (1:1) N-vinylpyrrolidone/N-vinyl-caprolactam (VP/VCap) is found to have the highest induction time (IT) of 13 to 14 h at 0.25 wt % and at a cooling rate of 1 °C/h. Some KHIs like Inhibex BIO-800 and poly(N-vinyl azacyclooctanone) (PVACO) also have a very high ITs (17 and 13.5 h, respectively) at 0.25 wt % and at a cooling rate of 1 °C/h, but they have low cloud points (<25 °C). Guanidinium salts (n-Bu6GuanCl/n-Bu6GuanBr) and a phosphonium salt, (n-Pe)4PBr, are found to be the best synergists for the cyclic-amide-based KHIs. When used at 0.15 to 0.30 wt % along with the KHIs, they further increase the IT by 3–5 h.

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“…Over the past three years, an array of these HPS-ALTA cells have been used to record thousands of hydrate formation events, across the range of accessible shear rates and compositions. , Efforts by Metaxas et al configured these cells to study induction time, which enabled a new probabilistic input for field-scale simulation with the above-described mechanistic model; the most recent efforts by Lim and co-workers , and Barwood et al have extended this induction time approach to study various KHIs as a function of concentration, with suggestions that systems containing KHI may not follow classical nucleation theory, which the HPS-ALTA system successfully established for pure guest–water systems . Together, the unique experimental capability and mechanistic model provide a means by which both the probability and severity of a hydrate formation event may be calculated.…”

Section: Structure–function Inhibitor Developmentmentioning

confidence: 99%

“…184 Together, the unique experimental capability and mechanistic model provide a means by which both the probability and severity of a hydrate formation event may be calculated. More importantly, recent efforts by Barwood et al 190 have demonstrated a superior ability to distinguish between KHI formulations and dosages through induction time trials, enabling structure−function development of future KHIs.…”

Section: Structure−function Inhibitormentioning

confidence: 99%

Hydrate Risk Management in Gas Transmission Lines

Aman

2021

Energy Fuels

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Gas hydrates are ice-like solids that can readily form and restrict flow in high-pressure natural gas transmission lines. The use of antifreeze thermodynamic inhibitors dominated production systems throughout the 20th century, where most research necessarily focused on measuring and predicting the hydrate phase boundary. In the 21st century, market competitiveness and environmental constraints have motivated a paradigm shift toward the identification and management of hydrate blockage risks, which has largely been facilitated to date through two research efforts: establishing and continuously refining mechanistic models to predict hydrate blockage formation; and exploiting critical stages within that blockage mechanism to develop novel, environmentally compatible inhibitors. This review presents a historical perspective on the development of an oil-dominant blockage mechanism and the technologies enabled by these efforts. Efforts over the past decademade possible through the collaboration between industry, the Australian government, and academiaare then summarized in the context of producing the first mechanistic blockage model for gas-dominant transmission lines, including the role of innovative high-pressure pilot-scale flowloop systems. Together, these blockage mechanisms have enabled new opportunities to develop and deploy low-dosage hydrate inhibitorsincluding the creation of new experimental capabilities that can be used to quantify occurrence probability or severity and the transient simulation tools that can leverage such knowledgethat support the ability to quantitatively manage hydrate blockage risk in hydrocarbon transmission lines. As they offer superior resolution in performance assessment to first-generation approaches, these new experimental methods offer structure–function design and optimization of low-dosage inhibitors against secondary, environmental parameters.

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High-resolution performance tests of nucleation and growth suppression by two kinetic hydrate inhibitors

Cited by 20 publications

References 44 publications

Aqueous Solid Formation Kinetics in High-Pressure Methane at Trace Water Concentrations

Aqueous Solid Formation Kinetics in High-Pressure Methane at Trace Water Concentrations

Review of Kinetic Hydrate Inhibitors Based on Cyclic Amides and Effect of Various Synergists

Hydrate Risk Management in Gas Transmission Lines

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