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Objective Experimental and mathematical fitting methods are used to develop a new approach for converting water content to dew point in natural gas to enhance conversion accuracy and reduce errors. Methods This paper adopts the combined application of gas standard substances, portable dew point mirrors, and Matlab mathematical software. Using cubic spline interpolation technique, it establishes a novel method for converting water content to water dew point. Results By utilizing surface fitting for the conversion of water dew point, this method achieves a Mean Absolute Error (MAE) of 1.16 ℃ and a Root Mean Square Error (RMSE) of 2.28 ℃, meeting the reasonably acceptable maximum deviation of 2.8 ℃. By comparing this method with the domestic and international mainstream conversion methods, the average absolute deviation of the three methods are 0.46% (cubic spline interpolation), 0.69% (GB/T 22634-2008 Conversion between water content and water dew point of natural gas), and 0.84% (ASTM D1142-95(2021) Standard test method for water vapor content of gaseous fuels by measurement of dew-point temperature), respectively, and the applicability of the three methods under different water content and pressure ranges is analyzed and explored. Conclusions Through comparative studies with experimental values, the cubic spline interpolation method shows better conversion accuracy for water volume fractions from 0 to 200×10-6 compared to standard methods, effectively reducing the conversion error between water content and water dew point. [ABSTRACT FROM AUTHOR]

TEG dehydration is an important technology for natural gas exploitation. The developmental tendencies of TEG dehydration process were discussed in this article. Recently inert gas stripping is the most popular measure to concentrate TEG and can improve the purity of TEG to 99.20％-99. 98% which correspond to the water dew point depression range of 55-83 °C for dry gas. The improved Drizo process can reduce the mass concentration of water to lower than 1X10-6, the dehydration efficiency may reach that of molecular sieve adsorption process. The TEG dehydration process can reduce BTEX/CO2 emission and recover aromatic,which will decrease CAPEX and OPEX also. Especially, Drizo process is suitable for FLNG engineering. At present brand-new equipments and materials are increasingly utilized in TEG dehydration unit,such as high-efficiency structured packing,electric gear pump,energy exchange pump and welded plate heat exchanger etc.. [ABSTRACT FROM AUTHOR]

Abstract: An advanced equation of state has been developed for modeling triethylene glycol (TEG)–water system for glycol gas dehydration process. The dehydration of natural gas is very important in the gas processing industry. It is necessary to remove water vapor present in a gas stream that may cause hydrate formation at low-temperature conditions that may plug the valves and fittings in gas pipelines. In addition, water vapor may cause corrosion difficulties when it reacts with hydrogen sulfide or carbon dioxide commonly present in gas streams. The most effective practice to remove water from natural gas streams is to use TEG in the gas dehydration process. In modeling such a process, it is crucial that the phase behavior of the TEG–water–natural gas system is correctly modeled, with methane being the predominant component in natural gas. Of the three binaries, methane–water, methane–TEG and TEG–water, the methane binaries can be adequately modeled by an equation of state, e.g. [J.R. Cunningham, J.E. Coon, C.H. Twu, Estimation of aromatic hydrocarbon emissions from glycol dehydration units using process simulation, in: Proceedings of the 72nd Annual Gas Processors Association Convention, San Antonio, TX, March 15–17, 1993]. For the TEG–water binary, the Parrish''s empirical hyperbolic correlation [W.R. Parrish, K.W. Won, M.E. Baltatu, Phase behavior of the triethylene glycol–water system and dehydration/regeneration design for extremely low dew point requirements, in: Proceedings of the 65th Annual GPA Convention, San Antonio, TX, March 10–12, 1986] is recommended by GPSA [GPSA Engineering Data Book, 10th ed., First Revision, Gas Processors Suppliers Association, Tulsa, OK, 1994] and is currently widely used in the industry. In this work, we applied the TST (Twu–Sim–Tassone) equation of state to model this binary system. A methodology was also developed to determine the water dew point and calculate water content for this system. The TST equation of state is shown to accurately represent the activity coefficients of TEG–water solutions as well as water dew point temperatures and water content of gas over the entire application range of temperature, pressure and concentration encountered in a typical TEG dehydration unit. [Copyright &y& Elsevier]