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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]

Water dew point is an important technical index of natural gas and similar gas, which is of great significance to the selection and control of natural gas and similar gas processing and transportation conditions with a correct understanding of the water dew point requirements of different product standards. The paper compares and analyzes the water dew point index requirements of GB 17820 Natural Gas, GB 18047 Compressed Natural Gas as Vehicle Fuel and GB/T 37124 Quality Requirement for Gases Eetering Long-distance Transportation Gas Pipeline, detailed interpretation of the criteria for determining whether the water dew point measurement results meeting the requirements of the technical provisions. At the same time, the attention point of measuring and judging water dew point results is analyzed in the form of example.The results show that the water dew point index of natural gas and similar gas can be divided into qualitative andquantitative indexes, and the qualitative index emphasizes that there should be no liquid water under the condition of pressure and temperature at the handover point, no need to detect the water content. At a certain pressure, the water dew point should be 5 ℃ lower than the minimum ambient temperature under the conveying condition. At this time, the standard users correctly understand "certain pressure" and "minimum ambient temperature" is the key to effectively judge whether the water dew point exceeding the limit value of standard. The ambient temperature-13 ℃ is as the boundary point for vehicle compressed natural gas, and the water dew point or water content is specified in two cases, its indexes are specific and clear with good operability. This paper puts forward the limitation of water dew point index stipulated by GB 18047-2017 and GB/T 37124-2018 standards, and gives some suggestions for revising relevant national standards in the future. The conclusion has reference value for the personnel engaged in natural gas analysis and testing and quality management to understand and use the standard correctly. It is also of practical significance for the safe and smooth operation of natural gas dehydration treatment plant and gas pipeline. [ABSTRACT FROM AUTHOR]

In the process of natural gas quality detection, the detection is mainly carried out according to the four indexes of calorific value, content of CO2, H2S and total sulfur, as well as water dew point specified in GB 17820 - 2018 Natural Gas. The detection of H2S and water dew point is completed by the analyst on site, while the detection of calorific value, content of CO2 and total sulfur needs to be obtained by on-site sampling, sample transportation and laboratory analysis. The completion of a single sample analysis cycle is long and the economic cost is higher. For this reason, a new type of mobile detection system for natural gas quality has been developed. At the same time, a sample processing system, an anti-vibration system and a data processing system have been designed, which can realize the on-site rapid detection, data processing and report generation of five indicators. The successful application in a natural gas purification plant (Plant A) and a gas transmission station (Station B) shows that the mobile detection system of natural gas quality can be applied to the on-site fast detection of four indicators and water dew point specified in GB 17820 - 2018 after the long-distance move and under the complex working condition. [ABSTRACT FROM AUTHOR]

Water dew point is an important indicator of natural gas quality control and pipelines safe operation, and also a key concern indicator in negotiation of technical agreement for importing Russian natural gas. The paper makes a detailed comparative study on the standard methods of China, ISO and Russia for determining water dew point of natural gas. Firstly, it is the comparison of standard content. Secondly, comparative test was carried out in different laboratories by using the gas source generated by the standard water dew point generator. Finally, according to the standards of China and Russia, the dew point instruments commonly used in the two countries are respectively used to carry out comparative tests at gas transmission stations under different blowing conditions. Through comparative study, it is clear that the biggest difference between the three standards is the blowing mode; in the condition of no interference, the test results of the common water dew point instrument in China and Russia are accurate, reliable and in good agreement with each other; in the presence of interference (possibly alcohols or hydrocarbons), the test results are quite different, the maximum difference is 6. 1 °C. This study provides a support for the technology negotiations of importing Russian natural gas. [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]

The moisture content and water dew point of natural gas are keys to its pipeline transportation. At present, the conversion software within natural gas moisture and dew point instrument has low accuracy. In order to solve this problem, an instrument of conversion for natural gas moisture content/water dew point based on OPC communication has been designed and developed. The experiment showed that the instrument could run real-time online and had good computational accuracy and efficiency. [ABSTRACT FROM AUTHOR]