P–T–x Measurement and Modeling of Methane or Carbon Dioxide + Methanol +2,2′-[Ethane-1,2-diylbis(oxy)] di(ethan-1-ol) Systems from T = 298 to 323 K

Abstract

In this work measurements and modeling of new phase equilibria data for systems related to natural gas processing were performed. A high-pressure apparatus functioning in the static synthetic mode was used to measure P–T–x data for the systems methane + methanol + 2,2′-[ethane-1,2-diylbis­(oxy)] di­(ethan-1-ol) (triethylene glycol (TEG)) (0.0333 methanol/0.9667 TEG wt fraction) and carbon dioxide + methanol + TEG (0.0333 methanol/0.9667 TEG wt fraction) at 303.16 and 323.15 K. Validation of the experimental technique was performed through measurement of P–T–x data for methane + TEG, methane + methanol, and carbon dioxide + water + TEG (0.0350 water/0.9650 TEG wt fraction) test systems from T = 298.15 to 323.15 K. The data were modeled using the Peng–Robinson equation of state with the Wong Sandler mixing rules (PRWS), the Cubic Plus Association (CPA) model, and the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) model, and predictions were performed with the predictive Soave–Redlich–Kwong (PSRK) model. For the methane + methanol + TEG and carbon dioxide + methanol + TEG systems, the PRWS model correlation yielded the best fit to the experimental data compared to the PC-SAFT and CPA models with a maximum absolute average relative deviation in pressure (AARD­(P)) not exceeding 0.0309.

P-T-x Measurement and Modeling of Methane + Propane + Methanol or 2,2′-[Ethane-1,2-diylbis(oxy)] Di(ethan-1-ol) and Methane + Propane + Methanol + 2,2′-[Ethane-1,2-diylbis(oxy)] Di(ethan-1-ol) Systems

“…The measured P-T-x data were modeled using the CPA and PC-SAFT models. These models show good correlating abilities and representation, as reported in our previous work . Detailed descriptions of the models and their equations are found in the original texts. , Temperature-dependent binary interaction parameters for both models have been regressed and are represented as k ij , where i and j represent specific components.…”

“…The experimental equipment used for bubble point pressure measurements has been described previously. , The device constitutes a horizontal view equilibrium cell fitted with a piston for volume and pressure manipulation. The visual synthetic mode used in this work was described in our previous paper . The sapphire cell has an approximate working volume capacity of 33 cm 3 .…”

“…A 20 dm 3 water bath with a TX Grant controller, model (Optima TX 150), maintained the cell temperature to within ±0.05 K. A syringe pump model 100DX (ISCO), controlled by SFX 200 controller (ISCO) connected to the hydraulic side flange, was used to drive the piston with water as the hydraulic fluid. The reader is referred to our previous article for further details and a layout of the apparatus.…”

“…Temperature probes and the pressure transducer were calibrated as outlined in our previous paper . The temperature probes were calibrated over a temperature range of 273.15 to 333.15 K against a (WIKA CTH6500) temperature standard inserted into a silicone oil M20 bath.…”

“…Knowledge about the solubilities of natural gas components in TEG is vital since the absorption of methane, propane, and volatile organic compounds (VOCs) impacts the TEG recirculation rates, energy savings, hydrocarbon loss minimization, and the design of TEG dehydration plants . Phase equilibria data for the methane + TEG and propane + TEG binary systems have been reported in the open literature. − TEG absorbs minute quantities of methane (0.0006 to 0.0840 methane mole fraction) over a pressure range of 0.11 to 20.2 MPa. − Furthermore, TEG absorbs VOCs, and air pollutants that are eventually emitted from the glycol regenerator unit into the atmosphere . Phase equilibria data for the propane + TEG binary system have been reported in the open literature for the propane mole fraction range of 0.0007 to 0.1096 over a pressure range of 0.02 to 7.06 MPa and a temperature range of 298.15 to 448.99 K. , Thus, the solubility of lower alkanes in TEG is important since these could constitute a loss to the TEG dehydration process. , No vapor–liquid equilibria literature data have been reported in the open literature for the methanol + TEG binary system.…”