Search

Objective Aiming at the problem of freezing and blocking of pipeline transportation in remote wells and scattered wells in the Tahe area, a pilot construction project of a small dehydration station which is unattended was carried out. Methods Considering the special problems of the skid, the skid-mounted molecular sieve dehydration plan was worked out. The export natural gas water dew point during the trial operation was detected and the complicated working conditions of sudden power outage was simulated to analyze the potential risk factors and take corresponding preventive measures. Results After testing, the highest water dew point of exported natural gas was-28 ℃, and the whole skid runs reliably. It can also ensure security even in sudden power outages in the absence of intervention. Conclusions The 200×10³ m³/d unattended molecular sieve dehydration skid has great advantages in cost, dehydration effect and safety operation, especially suitable for relocation-possible devices or remote areas. At the same time, it also has great adaptability for complex and changeable special working conditions. The skid can be actively promoted and applied. [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 index for measuring if the external gas reached the standard. The traditional method to test water dewpoint of natural gas has lots of disadvantages. This paper proposes a new method based on modified plate to obtain the actual water dew point in the process of TEG dehydration system. The plate expresses the relationship between the inlet gas temperature and the lean TEG mass fraction and the outlet balanced water dew point in the contact tower. The deviation between the balanced dew point and the actual dew point should be obtained before the measurement. In the measurement the gas inlet temperature and the mass fraction of lean TEG were collected to substitute into the plate to obtain the balanced dew point, correct the result with the known deviation to get the actual dew point. In order to accurately find the corresponding points in the plate, a professional software was developed. The new method with software is easy to operate and the measurement error is small. The new method can be widely used in gas field [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]

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]