Natural gas hydrate stability conditions and water activity in aqueous solutions containing mono ethylene glycol (MEG) and salt: Experimental measurements and thermodynamic modeling

Najibi, Hesam; Azimi, Arezoo; Javanmardi, Jafar; Roozbahani, Reza; Mohammadi, Amir H.

doi:10.1016/j.fluid.2021.113322

Cited by 8 publications

(12 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considering the measurement accuracy of 0.012, the effect of temperature is ignored. Besides, the rationality of ignoring the effect of temperature on water activity has also been described in several literatures 39–42 . The effect of pressure on water activity was also neglected due to the low solubility of methane in water 43 .…”

Section: Experiments and Modelmentioning

confidence: 99%

“…Besides, the rationality of ignoring the effect of temperature on water activity has also been described in several literatures. [39][40][41][42] The effect of pressure on water activity was also neglected due to the low solubility of methane in water. 43 The water activity meter was routinely calibrated to ensure the measurement accuracy.…”

Section: Water Activities Measurementmentioning

confidence: 99%

See 1 more Smart Citation

Experimental investigation and modeling on the dissociation conditions of methane hydrate in clayey silt cores

Sun

Yang

et al. 2022

AIChE Journal

View full text Add to dashboard Cite

As the majority of global natural gas hydrate reserve, the dissociation conditions of hydrate in clayey silts are of great significance for its efficient production. In this work, the dissociation conditions of methane hydrate in clayey silt cores were experimentally measured by step-heating method at the temperature range of 280.76-289.55 K and pressure range of 8.11-15.03 MPa, respectively. Various cores including quartz powder, montmorillonite, and South China Sea sediments at the water content range of 20%-33% were used for investigation. The results showed that the dissociation temperatures of methane hydrate in clayey silt cores depressed compared to bulk hydrate. The grain size, salinity, and lithology of clayey silt cores significantly affect the dissociation conditions of hydrate. In comparison to grain size, salinity, and lithology had a more significant influence on the equilibrium temperature depression.The dissociation temperature depression of methane hydrate was considered as a consequence of the water activity depression which is caused by the effect of capillary, salt, or clay. A water activity meter was used to measure the water activity in clayey silt cores. The influence of salt component and mineral characteristics on the water activity was investigated. By combining the measured water activity data with the Chen-Guo model, a novel water activity measurement (WAM) method for the hydrate dissociation conditions prediction was proposed. With the maximum deviation less than 12%, the predicted results are in good agreement with the experimental data. It demonstrated that the WAM method could effectively predict the dissociation conditions of methane hydrate in clayey silts with convenience and accuracy.

show abstract

Section: Experiments and Modelmentioning

confidence: 99%

Section: Water Activities Measurementmentioning

confidence: 99%

Experimental investigation and modeling on the dissociation conditions of methane hydrate in clayey silt cores

Sun

Yang

et al. 2022

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…Jia et al proposed a thermodynamic model based on the electrolyte CPA EOS and the Parrish–Prausnitz model to predict the multiphase equilibria of gas, liquid, and hydrate phases for systems containing acid gas, water, alcohol, and electrolyte components. Najibi et al predict the stability conditions of natural gas hydrates in the presence of MEG and salt mixtures. In their proposed thermodynamic model, the CPA EOS with the modified Debye–Hockel electrostatic expression is used to calculate the fugacity of the aqueous phase, and the vdW-P model is used to model the hydrate phase.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Evaluation of mER, PR, and PT EOSs Coupled with the UNIQUAC Activity Model for Predicting Gas Hydrate Formation Pressure in the Presence of Methanol and Monoethylene Glycol

Aghighi,

Bonyadi,

Darvishi

et al. 2024

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

In this study based on the van der Waals and Platteeuw model, the modified Esmaeilzadeh−Roshanfekr (mER), Patel−Teja (PT), and Peng−Robinson (PR) equations of state are coupled with the UNIQUAC activity model to predict gas hydrate formation pressure in the presence of methanol and monoethylene glycol (MEG). The results of these models were compared to the Delavar−Haghtalab model as well as to experimental data and each other. To allow for an impartial comparison of the suggested models, the binary interaction coefficients in the EOS mixing rules have been set to zero, and the UNIQUAC binary interaction parameters have been adjusted directly by utilizing the genetic algorithm for the hydrate experimental data. The total average absolute percentage deviations between predicted hydrate formation pressures and experimental data of pure and mixed gas systems show that the mER-UNIQUAC model with an AAD of 4.21% is more accurate than the PT-UNIQUAC model, which has an AAD of 4.39%, and the PR-UNIQUAC model, which has an AAD of 5.53%. Furthermore, the mER-UNIQUAC, PT-UNIQUAC, and PR-UNIQUAC models had fewer errors than the Delavar−Haghtalab model, indicating that these models can be used to accurately predict the hydrate formation pressure in the presence of methanol and MEG.

show abstract

“…36 Najibi et al developed a model to compute gas hydrate dissociation conditions for alcohol + salt solutions. 37 Mohammadi and Tohidi calculated hydrate dissociation conditions for the system water + alcohols + salts utilizing a combined equation of state and activity coefficient-based model. 38 Hu et al proposed a correlation (HLS) of the hydrate suppression temperature from the uninhibited system.…”

Section: Introductionmentioning

confidence: 99%

“…Jiang and Adidharma computed the hydrate dissociation conditions in the presence of alcohol + electrolyte solutions using an ion-based statistical associating fluid theory (SAFT2) in conjunction with the vdW-P theory . Najibi et al developed a model to compute gas hydrate dissociation conditions for alcohol + salt solutions . Mohammadi and Tohidi calculated hydrate dissociation conditions for the system water + alcohols + salts utilizing a combined equation of state and activity coefficient-based model .…”

Section: Introductionmentioning

confidence: 99%

A Precise Thermodynamic Approach for Calculating Activity of Water in the Presence of Aqueous Alcohol + Salt Solutions and its Application to Gas Hydrate Dissociation Modeling

Keshavarzi,

Rasoolzadeh,

Nasrifar

2024

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Thermodynamic hydrate inhibitors (THIs) are chemical compounds that are utilized to reduce the activity of water and consequently restrict the hydrate formation zone, which is managed as a result of strong molecular/ionic interactions with water without further participating in the hydrate structure. In this regard, developing a precise and easy-to-use thermodynamic relation to calculate the activity of water in the presence of aqueous THI such as alcohols and salts is of great importance. Such a relation can then be employed within a thermodynamic approach to model hydrate equilibria. The goal of this work was to derive a relationship from the Gibbs−Duhem theory to calculate hydrate dissociation temperatures in the presence of aqueous alcohol + salt solutions. As such, the interactions between salts and mixed solvents (water + alcohol) were described phenomenologically using the Bromley model. The results find applications in the gas and oil industry. To describe the hydrate phase, the van der Waals−Platteeuw (vdW-P) model was utilized. The Peng−Robinson equation of state (EoS) was used to describe the gas phase. To calculate the activity of water in the salt-free water + alcohol solution, the UNIQUAC and Flory models were employed, and to calculate the activity of water in the alcohol-free water + salt solution, the Bromley and Pitzer models were employed. The predictions of the model were compared to the Delavar and Haghtalab, Mohammadi and Tohidi, and Hu-Lee-Sum (HLS) calculations. The new approach developed herein yielded accurate results for a databank of 613 data points of gas hydrate dissociations in the presence of alcohol solutions with average absolute deviations (AAD) of 0.79 K. For prediction of the gas hydrate dissociation temperature in the presence of aqueous salt solutions, the vdW-P + PR + Bromley model resulted in a notably enhanced accuracy with an AAD of 0.52 K for 1065 data points. Our research concludes with the superiority of this work, when the activity of water was used together with vdW-P + PR + UNIQUAC + Bromley. With an AAD of 0.68 K for 544 data points, the model reliably predicted gas hydrate dissociation temperatures in the presence of aqueous alcohol + salt solutions.

show abstract

Natural gas hydrate stability conditions and water activity in aqueous solutions containing mono ethylene glycol (MEG) and salt: Experimental measurements and thermodynamic modeling

Cited by 8 publications

References 38 publications

Experimental investigation and modeling on the dissociation conditions of methane hydrate in clayey silt cores

Experimental investigation and modeling on the dissociation conditions of methane hydrate in clayey silt cores

A Comparative Evaluation of mER, PR, and PT EOSs Coupled with the UNIQUAC Activity Model for Predicting Gas Hydrate Formation Pressure in the Presence of Methanol and Monoethylene Glycol

A Precise Thermodynamic Approach for Calculating Activity of Water in the Presence of Aqueous Alcohol + Salt Solutions and its Application to Gas Hydrate Dissociation Modeling

Contact Info

Product

Resources

About