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Objectives The aim is to solve the problems of low dehydration efficiency and high energy consumption in triethylene glycol dehydration process, and optimize the operating parameters. Methods The sensitivity analysis method and response surface method were used to optimize the operating parameters. (1) Sensitivity analysis method was used to select the rich liquid entering- tower temperature, reboiler temperature. lean TEG circulation volume flow. stripping gas volume flow as factor variables, and to select dry gas water dew point and operating cost as response values. and 25 groups of test data were simulated by HYSYS software. (2) The response surface method was used to analyze and optimize these operating parameters. Results The interaction between rich liquid entering-tower temperature and stripping gas volume flow rate had the most significant influence on the dew point of dry gas water. and the interaction between rich liquid entering-tower temperature and lean TEG circulation flow rate had the most significant influence on the operating cost. The optimal process parameters were as follows: The temperature of rich liquid entering tower was 144. 28 C, the temperature of reboiler was 205.4 C. the circulation flow rate of lean TEG was 4 m³/h, and the volume flow of stripping gas was 24. 96 m/h. Under the condition that the dew point of dry gas water met the requirements of external transmission and the natural gas treatment capacity was 3 000 X 10³ m³/d. the operating cost could be reduced by 693 300 yuan per year. Conclusions The response surface method can be used to provide the theoretical basis of field operation parameter optimization. [ABSTRACT FROM AUTHOR]

In this study, the formation of natural gas liquid in gas distribution lines, particularly at regional stations, service boxes, customer installations, and gas meters, was investigated. The study aims to address the problems associated with natural gas liquid formation, such as interruption of supply and decreased efficiency of combustion devices. The indirect measurement of the hydrocarbon dew point was analyzed using C6+ chromatograph data, and the model based on directly measured C6+ data were converted into C6/C7/C8 data by four different methods. As distinct from studies in the literature, this study experimentally determines the distribution of heavy hydrocarbons from C9 to C19 based on indirect methods for acquiring C8+ data and direct measurement of C6+ data. The hydrocarbon dew point temperature was calculated using the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state. The results of the analysis performed on two city gate stations showed that the critical temperatures were 4.21 °C at a pressure of 10.81 bar and 8.27 °C at a pressure of 11.25 bar, respectively. These values were obtained from a model designed to determine the dew point temperature in the area where natural gas liquid formation was most prevalent. The experimental analysis and indirect measurements indicated the occurrence of a two-phase gas–liquid formation. [ABSTRACT FROM AUTHOR]

Petrochemical equipment is characterized by continuity, large scale, complexity of processes, and critical operation conditions. Based on auto-collected monitoring parameters, online prediction of critical process parameters can be used to maintain high reliability of petrochemical equipment, which is generally unpractical due to interference parameters and the difficulty in establishing prediction models. In this paper, a process parameter online prediction method for petrochemical equipment is proposed. Firstly, sensitive parameters are selected applying gradient boosting decision tree (GBDT). Then optimized Gaussian process (GP) is utilized to develop a mapping model in order to inference process parameter from auto-collected parameters. Natural gas water dew point online prediction method for triethylene glycol (TEG) dehydration unit is investigated. The effectiveness of the proposed method is verified on production data of a natural gas dehydration station. The method proposed provides a promising solution for process parameter prediction for petrochemical processes as well as other similar scenarios. [ABSTRACT FROM AUTHOR]

The natural gas liquid recovery is an important process in a gas plant to correct hydrocarbon dew point and earn profit. In this study, a natural gas liquid recovery unit operated based on the Joule–Thomson process was investigated and its performance was optimized. To improve the system performance, the plant configuration and intermediate pressure ratio were defined as the variables and maximization of the natural gas liquid recovery rate and maximization of exergy efficiency were defined as the objective functions. To improve the plant performance, the amount of natural gas liquid recovery rate should be increased. To achieve this goal, several scenarios for the intermediate pressure ratio and three new configurations were proposed for the investigated gas plant. In the proposed configurations, the supersonic separators with optimized structures were used instead of the Joule–Thomson process. It was observed that all three proposed configurations improved the natural gas liquid recovery rate compared to the existing configuration. For example, by installing two supersonic separators instead of second and third stage Joule–Thomson valve + low temperature separator, at the optimal operating condition, the natural gas liquid recovery rate increased about 390%. The influence of the intermediate pressure ratio on the phase envelope diagram, exergy efficiency, dew point depression and natural gas liquid recovery rate was also investigated. By comparing the influence of intermediate pressure ratio and modifying the plant configuration on the objective functions, it was observed that the system performance can be further improved by modifying the plant configuration. [ABSTRACT FROM AUTHOR]

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]

In this study, a water- and heavy hydrocarbon-removal process of a natural gas refinery currently in operation using the temperature swing adsorption method is modeled and investigated. The aim of this process is to decrease the hydrocarbon dew point to −10 °C and diminish the water content of the gas to about 0.1 ppm. This unit consists of four beds with two layers in which two beds are in the adsorption state, while the others are kept in the regeneration state. The gas composition and the bed specification are obtained from the available data from the refinery. The Ergun equation is considered for the pressure drop calculation. The results show that the developed model can predict the outputs with good accuracy. Sensitivity analysis of operating condition parameters such as temperature, pressure, and regeneration gas flowrate are carried out. Analysis of the regeneration temperature proved that temperature reduction from 268 °C to 210 °C can improve recovery of the heavy components. In addition, the regeneration gas flow rate can be reduced to about 0.4 kmole·s−1 as an optimum value. Moreover, 303 to 310 °C is the optimum range for the feed temperature. Due to the presence of the air cooler in the upstream process, and according to the ambient air temperature, feed temperature can be decreased to obtain better results. [ABSTRACT FROM AUTHOR]

The main application of high-flow Ranque–Hilsch three-flow vortex tubes (TVT) is the low-temperature separation (LTS) of natural gas with vortex tubes used as cold generators and direct separators. In this study, we compare the purification efficiencies of TVT and the throttle at the LTS unit used at the Beregovoye field characterized by a low degree of gas expansion (pressure drop from 85 bar to 60 bar). We observed that the gas temperature and its dew point temperature was lower for TVT compared to that for the throttle used at the LTS. Moreover, use of TVT increased the degree of gas purification even at low degrees of gas expansion. This ensured the implementation of Gazprom Company standard 089–2010 for the summer conditions. [ABSTRACT FROM AUTHOR]

Objective The design pressure of partial system of natural gas ethane recovery project in Tarim oilfield reaches 8.0 MPa, and hydraulic pressure test mode is adopted to ensure the safety of pipeline equipment strength pressure test in the construction process. In order to avoid freezing and blocking of hydrostatic test unit and ensure smooth test run and long-term stable operation of the unit, it is necessary to efficiently complete the drying operation of the gas cryogenic recovery unit before it is put into operation. Methods On the basis of a comprehensive investigation and analysis of the drying methods commonly used in domestic natural gas cryogenic units and their shortcomings, the cyclic drying technology is optimized and improved in the natural gas ethane recovery project of Tarim oilfield. Results After the later commissioning and operation test of the device, the fumble cycle drying technology has good drying effect, and the "nearly zero discharge" of drying gas is realized, the freezing and blocking problems after the hydraulic pressure test of the device are effectively avoided. Conclusions（1） Even if the pneumatic test device is used, it is recommended to carry out the system drying before production;（2） Based on engineering practice, the determination principles of parameters such as cyclic drying pressure, flow rate, temperature and water dew point detection are defined;（3） In view of the shortcomings existing in practice, practical solutions and suggestions are put forward, which can provide reference for drying operation and related design of other natural gas cryogenic units. [ABSTRACT FROM AUTHOR]

Objective In the gathering and transportation of natural gas mines with high hydrogen sulfide content, in order to effectively reduce the corrosion hazard of hydrogen sulfide to the system, dehydration is often used to control the water dew point. Methods Based on the research of dehydration technology of high sulfur natural gas at home and abroad, triethylene glycol solvent absorption method was selected as the dehydration treatment process of high sulfur natural gas in Shunbei No. 2 area. Considering the characteristics of high sulfur natural gas in Shunbei No. 2 area, the traditional triethylene glycol dehydration process was optimized and improved locally, and the separation process before the raw gas inlet adsorption tower and the flash-vapor recovery process were added at the same time. Based on the influence of the pre-heating location, regeneration purity and hydrogen sulfide, the paper adopted a two-stage low-liquid/high-liquid heat exchange pre-heating process and LNG gasification gas extraction process to form a dehydration process which is suitable for high-sulfur natural gas in Shunbei No. 2 area. Results After transformation, the dehydration process realized zero discharge of sulfur-containing tail gas from dehydration system by pressurized recovery, and the combination of efficient desulfurization and purification of triethylene glycol (TEG) realized by LNG gasification and gas stripping, the problem of corrosion and maintenance of regeneration device in acid environment was solved. Conclusions This dehydration process effectively promoted the realization of the overall development plan of Shunbei No. 2 area, and formed a high-pressure gathering and transportation dehydration process suitable for natural gas with high hydrogen sulfide content in Shunbei No. 2 area, which provides technical support for the further development of Shunbei natural gas blocks. [ABSTRACT FROM AUTHOR]

The presence of sulphur in marine fuel oil relates to health and environmental concerns, as the respective combustion generates sulphur dioxide (SO2). The only method to control this SO2 generation is to limit the quantity of sulphur in the fuel. Shipping activities, although not the main source, contribute around 13% of the total anthropogenic SO2 IMO-3GHG [2015. Third IMO Greenhouse Gas Study, 3rd ed. London: International Maritime Organisation]; on a positive note, this is expected to reduce after the worldwide implementation of 0.5% sulphur regulation for marine fuel. One of the accepted methods to comply with the regulatory criteria is the use of alternate fuel, i.e. liquefied natural gas (LNG). The analysis in hand discusses the potential benefits of LNG as a marine fuel. The technical limitation associated with the formation of sulphuric acid (H2SO4) is directly related to its Dew point, as it condenses below 160°C and causes acidic corrosion of machinery components. The prevalent combustion-based systems are maintaining a safe and economical exhaust gas range between 150°C and 170°C. If the exhaust gas temperature is higher than 170°C excessive heat is lost, which makes the plant inefficient; in contrast, if the temperature drops below 150°C there is the possibility of corrosion damage to the equipment. Considering that LNG is absolutely free from sulphur contamination, it can be used to overcome this technical limitation and add to the overall thermal efficiency due to the availability of increased operating range. [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]

During the process of natural gas treatment in Keshen Treatment Plant, the wax precipitation from J-T valve and low-temperature separator caused the blockage of system, which limited the capacity of natural gas unit and caused unqualified hydrocarbon dew point of exported gas. The wax prevention process was studied to solve the problem. Through experiments and HYSYS software simulation, the specific causes of wax blockage were analyzed. It was concluded that the natural gas components in Keshen block were discontinuous. Due to the lack of C. to Cs components, polycyclic aromatic hydrocarbons existed in the gas phase and could not be dissolved and separated, so it was easy to condense and precipitate after entering the low temperature environment, which eventually led to the internals blockage of the low temperature separator. Through the experiment, field operation experience and theoretical calculation, the technical solution route was formulated according to the principle of similar compatibility principle. Through HYSYS simulation analysis, light hydrocarbon was injected from the front of the feed gas air cooler to supplement the missing components, so as to solve the problem of wax plugging, and the design capacity of a single treatment unit was restored. The accuracy of component analysis of wellhead natural gas was very important for the design of processing device. The requirement for component analysis of newly developed gas field was inc reased from C7 to C30, and corresponding component analysis method was formed. The research results were successfully applied to Keshen Treatment l'lant with wax plugging, and good results were obtained, which has a reference for the construction of similar waxy gas field. [ABSTRACT FROM AUTHOR]

With implementation of GB 17820-2018 Natural Gas. the purification plants under the Natural Gas Purification Plant General of Southwest Oil and Gasfield Company are faced with the requirement of class I gus index value for product natural gas. To achieve the requirement of new. standard GB 17820-2018. the existing configuration of on-line monitoring equipment are analyzed by compared with the new standard. According to the correlation degree between the five quality index values(the calorific value, total sulfur content, hydrogen sulfide content. carbon dioxide content and water dew point) and the gas purification plant. the configuration suggestions and application. management improvement measures of on-line analyzer are put forward in order to achieve the purpose. of reasonable configuration and use of on-line analyzer for product quality index monitoring. The research results show that: (1) among the five quality indexes of natural gas high calorific value. total sulfur content. hydrogen sulfide content. carbon dioxide content and water dew point. in which high calorific value and carbon dioxide content are easy to meet the index value. but water dew point, total sulfur content and hydrogen sulfide content are the key and difficult points in the operation and control of natural gas purification plant, which is easy to exceed the index value in the production: (2) the water on-line analyzer currently configured in each natural gas purification plant can meet the requirements of water dew point monitoring in GB 17820-2018 and continue to be used: (3) the hydrogen sulfide on line analyzer currently configured can not meet the requirements of hydrogen sullide content monitoring in GB 17820-2018 and needs to be reselected and replaced, (4) the quantity of total sulfur on line analyzer needs to be added: (5) the configuration of carbon dioxide on line analyzer remains the status quoi (6) the calorific value on-line analyzer is not available for the time being consider. [ABSTRACT FROM AUTHOR]

In order to optimize the energy consumption of the natural gas dew point control system under meeting the requirement of dew point at the junction point, HYSYS model is used to establish steady simulation to perform the sensitivity analysis of the key parameters affecting the dew point,including feed gas pressure and temperature, TEG circulation flowrate, reboiler temperature, stripping gas flowrate and J-T valve front temperature, and the reasonable value range of the key parameters,then the value range of which is determined. On this basis, the process parameters are optimized by the optimizer module of HYSYS and the optimal combination of process parameters is obtained. In view of the phenomenon of natural gas reverse condensation, the product gas envelope is used to check dew point during transporting. The results show that the pressure-temperature curve along the pipeline is on the right side of the dew point line, which proves that the product gas is always transported in gas phase [ABSTRACT FROM AUTHOR]

Hydrogen-enriched natural gas (HENG) is one of the significant ways to store, transport, and utilize hydrogen energy. This paper presents the characteristics of HENG and flue gas, energy saving, carbon reduction, and condensate recovery potential of flue gas waste heat. Based on the theoretical and experimental study of the existing flue gas condensing heat exchanger (FGCHE) added at the rail of gas-fired boiler, the performance of the FGCHE under different hydrogen blending ratios is studied. The results show that augmenting the hydrogen blending ratio decreases the volume heating value of HENG, and CO 2 content of flue gas. Meanwhile, the mass heating value of the HENG, the water vapor content, and dew point temperature of flue gas increase as the hydrogen blending ratio increases. The flue gas waste heat recovery utilization ratio and energy-saving efficiency of the FGCHE can be promoted. Moreover, the heat transfer capacity of the FGCHE using HENG is enhanced, while the flue gas flow pressure drop is reduced. Compared with the FGCHE used in pure natural gas systems, the all-hydrogen system increases the flue gas waste heat recovery amount by 62.4–120.4 %, reduces the flue gas flow pressure drop by 33.9 %, and reduces the carbon emission by 100 %. • Investigation of the HENG's heating value and flue gas characteristics. • The energy saving and carbon reduction potential of HENG's flue gas is studied. • The heat transfer capacity of the existing FGCHE in the HENG system is enhanced. • The flue gas flow pressure drop of the FGCHE in the HENG system is decreased. [ABSTRACT FROM AUTHOR]

The use of gas-lift systems for chemical injection presents a smart solution in numerous cases, particularly when production wells are already equipped with such systems. However, ensuring optimal operating conditions demands a thorough understanding of the phase equilibria curves of natural gas - inhibitor mixtures. The primary objective of this study is to experimentally determine the dew point curve of the methane - ethanol mixture, with methane being a significant constituent of natural gases, and ethanol being one of the most widely utilized gas hydrate inhibitors. The experiments covered temperatures within the range of 313.15–353.15 K and pressures ranging from 1.2 MPa to 8.5 MPa. Both visual and acoustic techniques were applied as synthetic methods to obtain accurate data. Additionally, a thermodynamic model employing the Cubic-Plus-Association (CPA) equation of state, fine-tuned with the experimental bubble and dew point data, was utilized to establish the dew point curve under optimized conditions. An average absolute relative deviation of 4.4% was obtained between the experimental dew points obtained in this work and the thermodynamic model. Moreover, this study fills a noticeable gap in the literature by providing reliable experimental data, which had been scarce. Furthermore, the acoustic experimental technique showcased in this work presents a feasible option for determining dew points. By gaining deeper insights into the behavior of the methane - ethanol mixture, this research contributes to the enhancement of gas-lift systems' efficiency and reliability in chemical injection applications. The findings are expected to have a positive impact on flow assurance strategies and ensure safer and more efficient operations in oil and gas production. [Display omitted] • New experimental dew point data for CH4 - C2H6O mixture for pressures between 1.0 and 8 MPa is presented. • Results shows that the acoustic technique combined with the visual one is suitable to detect dew point formation. • Cubic-Plus-Association equation of state was applied to describe the dew point behavior in the conditions of interest. [ABSTRACT FROM AUTHOR]

In view of the salt deposition problem in TEG dehydration system of the natural gas purification unit, which caused scaling on the solvent side of the reboiler and the water dew point rising of the product natural gas, the TEG solution component and the scale sample component were analyzed through the infrared spectrum analysis and liquid-mass spectrometry analysis etc. Combined with the actual process control situation on site, the reason of salt deposition was determined as salt compounds and organic solvents entering into the TEG system with natural gas, which caused the TEG to deteriorate and form scale. The experiment compared and selected ten kinds of solid materials. The results showed that macroporous adsorption resin DlOl has a better purification effect on TEG, which can provide references for similar devices to solve similar problems. [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]

In this paper, the DBR all-visible mercury-free high-temperature and high-pressure multifunctional formation fluid PVT analyzer developed and produced by Schlumberger company is used to conduct an experimental study on phase behavior characteristics of one offshore high CO2 condensate gas wells. The experiments include two-phase flash experiment, constant composition expansion experiment (CCE experiment), and constant volume depletion experiment (CVD experiment). Experimental results show that the higher the CO2 content in the condensate gas system, the higher the gas-oil ratio of condensate gas, the greater the density of condensate oil, the higher the dew point pressure of condensate gas, the greater the relative volume of condensate gas, the smaller the amount of retrograde condensate oil. And the higher the CO2 content in the condensate gas system, the phase diagram is shifted to the left and up, the critical point of the phase diagram is shifted to the lower left, the smaller the area of the two-phase envelope, the lighter the condensate gas system, the condensate oil recovery is higher. The above experimental results revealed that CO2 is well soluble with condensate gas, the expansion capacity of the condensate gas system was slightly enhanced, and because CO2 has a good extraction capacity, the light components of condensate gas were constantly extracted, the retrograde condensate rate of condensate oil decreases, and the maximum retrograde condensate volume also decreased. However, the condensate oil was produced along with the natural gas, and the higher the CO2 content, the stronger the extraction, the more condensate oil was produced. It is mainly because CO2 has the strong gasification and extraction capacity, on the one hand, the retrograde condensation of condensate gas was inhibited, and on the other hand, reverse evaporation of condensate oil was enhanced. The above experimental results indicate the law of the effect of CO2 on the phase behavior characteristics of condensate gas reservoirs, providing theoretical basis and guidance for the efficient development of condensate gas reservoirs at sea. [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]

The low temperature absorption method is currently used in a gas-processing unit to control the natural gas dew point. The major problem of this unit is the simultaneous absorption of high amount of methane within heavier hydrocarbons, which leads to low purity of ethane and propane streams. Considering the operational conditions, the mentioned method used in second and third phases, will control the dew point at −23° c at the best condition. This temperature is not proper for dew point and shows very high amount of hydrocarbons in product gas. In this study, a new process has been introduced in order to drop the gas liquid dew point (natural gas liquid) to −85° c by self-refrigeration technology. Due to the advanced nature of absorption process, the problem of methane existence in the product of gas liquids is noticeably overcome. In this process, natural gas enters the turbo expander after passing through a refrigeration cycle at −37° c and it is then expanded in an isotropic process to 2896 kPa pressure. Expander outlet with reflux and condensate produced from a cold separator are fed to an absorption tower with a reboiler and the separation will occur. The advantage of this method is controlling the concentration of methane in the product streams. Simulation results show that the process can daily produce 22,280 barrels of gas liquids with a concentration of 0.5 mole% of methane. In addition, the recovery efficiencies of propane and butane in the newly proposed method are 97.3% and 99.99%, respectively, which show a remarkable advantage over the current trend. [ABSTRACT FROM AUTHOR]

During the shutdown stage of Puguang Natural Gas Purification Plant, with the reducing temperature in the exhaust incinerator waste heat boiler, the internal gas is easy to form acid fog with water vapor, causing sulfuric acid dew point corrosion and safety risks. Currently, 5 w% NaOH was used as the shutdown protection agent to reduce acid corrosion, but the effect was not good. Besides, precautions for corrsions including bacterial corrosion, oxygen corrosion were not applied. In this experimental study, the type of corrosion was determined by analyzing the composition of the sampling fluid at the site, and the formulation of the shutdown protection agent was optimized. Through three factors and three level experiments, special experiment and effect verification experiment, the components of the shutdown protection agent was confirmed, which were 7 w% NaOH, 0.15 g/L bactericide 1227 and 1.5 g/L Na2SO3 without water. Its anti-corrosion effect is obviously better than that of the original agent. [ABSTRACT FROM AUTHOR]

Phase characteristic parameters of natural gas are of particular concern for condensate gas reservoir development and long distance pipeline transmission. Based on cubic equation of state, the calculation method for natural gas critical parameters, such as cricondenbar point, cricondentherm point and phase envelope curve is established. The comparison results between natural gas hydrocarbon dew point measurement values and prediction values has verified that the calculation method is quite accurate. The established calculation method is employed to predict the phase envelope curves of different natural gas compositions meeting different hydrocarbon dew point requirements. The result shows that the formation of hydrocarbon liquids cannot be avoided in the midstream or downstream of pipeline during natural gas transmission in the case of hydrocarbon dew point index meeting the requirement of the current national standards at upstream connection station, which is harmful to smooth and efficient operation of natural gas distribution system. Finally, the present article suggests that the cricondentherm temperature should be taken as an important reference to quantify the natural gas hydrocarbon dew point index. [ABSTRACT FROM AUTHOR]

High pressure sales gas may appear to have retrograde phenomenon because of pressure reduce and condense liquid drops of heavy hydrocarbon in gas phase at the special operating conditions of gas transportation and distribution system. Therefore the dew point index should be stipulated to guarantee safe and smooth operation of the system. Because composition of natural gas is very complicated and its phase behavior is absolutely different from other gas mixtures of single or multiple components, measurement of hydrocarbon dew point for sales gas is extremely difficult. Three methods of hydrocarbon dew point measurement and relative traceable way are briefly introduced in this article. Methods using manual or automatic hydrocarbon dew point chilled mirror instrument are that of physical property determination. These methods are not provided with traceability and the uncertainty of results of determination can not be assessed. The technical characteristic of PHLC method is that of establishment traceable procedure for chilled mirror instrument based on substantial relationship between hydrocarbon dew point value and PHLC at same pressure. Presently the accuracy of an advanced chilled mirror instrument has already reached ±0.5 °C. The method for calculation of hydrocarbon dew point by state equation is based on strict chemical thermodynamics and its application is not very popular because of influences of sampling representativeness, analytical accuracy and data processing. [ABSTRACT FROM AUTHOR]

In order to optimize the TEG dehydration process in an offshore gas field, determine reasonable parameters and achieve the optimal treatment effect, the HYSYS model was established to make a simulation under certain working conditions that the natural gas treatment capacity was 2X 106 m3/d, the operation pressure (gauge pressure) of absorber was 10 600 kPa, and the lean TEG circulation was 1. 17 m3/h. The relationship between independent variables and dependent variables was obtained by simulating and optimizing the inlet temperature of natural gas and lean TEG, lean TEG mass fraction, reboiler temperature, and stripping gas flow. On this basis, the optimum operation parameters were obtained to guide the process. It was verified that under the conditions of optimum parameters that the inlet temperature of natural gas was 33 °C , the inlet temperature of lean TEG was 40 °C and the lean TEG mass fraction was 99. 30% , the natural gas dehydration system operated normally, and the dew point of the dry natural gas reached the standard of natural gas transportation in platform. It showed that the HYSYS software could simulate and optimize the field process parameters according to the actual working conditions, and the results were relatively accurate. It could he popularized and applied in other offshore gas field. [ABSTRACT FROM AUTHOR]

• Experimental measurements VL phase equilibria are presented. • Dew pressure and liquid dropout data for methane + alcohol (methanol or ethanol). • Higher liquid dropout values for methane + ethanol system. • Thermodynamic modelling by using CPA equation of state. Hydrate inhibitor injection through gas-lift flow is used in production fields. The gas + inhibitor system's phase behavior provides essential information regarding monophasic regions and operational safety conditions. Methane is the main constituent of natural gas and is commonly used as a model component to represent gas reservoir fluids. However, pressure variation during a gas-lift injection can cause liquid dropout at valve injection. Therefore, phase behavior knowledge of methane + alcohol mixtures is potentially interesting in the oil and gas industry. In this work, dew pressure and liquid dropout data were experimental measured for methane + methanol (96.60 mol % CH 4) and methane + ethanol (96.50 mol % CH 4) systems in the temperature domain of 313.15 to 366.65 K and pressure up to 70 MPa. The CPA equation of state was used to correlate dew pressure and liquid dropout data for all systems, presenting a dew pressure absolute relative deviation of 6.89 and 5.22 % for methane + methanol (96.60 mol % CH4) and methane + ethanol (96.50 mol % CH4), respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights • Low-temperature steam conversion of flare gases into methane-rich mixtures. • Conversion of C 2+ -hydrocarbons to CH 4 , CO 2 and H 2. • Lowering net calorific value, Wobbe index and dew point temperature of the gas. • Partial conversion of C 2 H 6 and C 3 H 8 to reach desired gas properties. • Kinetic simulation and prediction of optimal reaction conditions. Abstract The present work aims at studying low-temperature steam conversion of model flare gas mixtures containing C 2 H 6 -C 5 H 12 in methane excess over industrial Ni-based catalyst. It is shown that at 250–350 °C and H 2 O/C C2+ molar ratio of 0.7–1.0, steam conversion can be applied to convert C 2+ -hydrocarbons into CH 4 , CO 2 and H 2 , which results in the lowering net calorific value, the Wobbe index and dew point temperature of the gas obtained. However, complete conversion is not necessary for certain applications. In these cases, kinetically controlled partial conversion of ethane and propane enables one to obtain methane-rich mixtures with desired calorific properties for various applications. This idea has been experimentally verified. Kinetic study of C 2 H 6 -C 5 H 12 low-temperature steam conversion has been performed. A simple macrokinetic model, which included irreversible first-order kinetics for C 2 H 6 -C 5 H 12 steam conversion and quasi-equilibrium mode for CO 2 methanation, has been suggested. The model adequately describes the experimental data on the conversion of model flare gas mixtures at various temperatures and flow rates and has been applied to predict the reaction conditions which would allow one to obtain methane-rich mixtures with the desired properties for various applications. [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]

The aim of this paper is to predict the equilibrium water dew point of natural gas in TEG dehydration process using feedforward artificial neural network (FANN). The ANN model shows a good result as the coefficient of determination of 0.9989 and 0.9976 was obtained for training and testing data respectively with relatively small value of mean square errors of 0.0203 and 0.0221. 0.5% of average absolute deviation percentage was observed which is comparable with the literatures. It clearly shows that FANN gives a good prediction on water dew point of natural gas in TEG dehydration process. [ABSTRACT FROM AUTHOR]

Hydrate formation and water accumulation during transmission process can be prevented by effective dehydration of gas streams. This study investigates the application of support vector machine to estimate natural gas dew point temperature using contactor temperature and TEG purity as independent variables. A data set comprised of 173 data points is extracted from the literature. The proposed model is considered a great help for engineers to have precise dew point temperature predictive tool in wide ranges of concerning variables. Results obtained from the proposed model show R-squared and mean square error of 0.992 and 5.556, respectively. Accordingly, the remarkable agreement between predicted and experimental values is observed. [ABSTRACT FROM AUTHOR]

Dehydration is a critical operation in natural gas conditioning as it reduces the potential for corrosion, hydrate formation and freezing in process equipment and transportation pipelines. Water dew point adjustment is particularly challenging in the remote ultra-deepwater natural gas reserves of the Brazilian Pre-Salt fields due to their very high carbon dioxide contents – from 30% up to 90% in raw natural gas – which is a consequence from the carbonaceous rock of the reservoir structure and long term elevation of carbon dioxide content due to its injection for early enhanced oil recovery. Under this scenario, the study evaluates the impact of the carbon dioxide content of the natural gas on the performance of water dew point via water adsorption on 4 Å Zeolite molecular sieve beds. Process simulation with adsorption simulator Adsim (Aspen Technology, Inc), at varying operation pressures and carbon dioxide contents in raw natural gas, indicated that, although adsorption meets water removal specification in a condensation free operation, the high fugacity of carbon dioxide penalizes the dehydration performance due to probably two facts: (i) higher carbon dioxide fugacity in the humid natural gas imply higher saturation water content in the gas phase, which increases the service of dehydration units; and (ii) higher carbon dioxide fugacity in the humid natural gas establishes a discreet adsorption competition with water resulting in 6.5% increase of adsorbent bed volume for operating pressures of 35 bar or higher. [ABSTRACT FROM AUTHOR]

Natural gas dehydration is a crucial step in gas processing, and three-flow vortex tubes have numerous advantages over traditional dehydration methods. In this study, a three-flow vortex tube with a sintered metal porous material as the drain part was developed. Further, the gas–liquid behavior within the main tube and sintered metal porous material (SMPM) was experimentally analyzed. Owing to the different driving forces, the gas and liquid first separate in the main tube, followed by further separation in the SMPM. With the SMPM as the drain part, the adverse impact of the drain processes and the amount of discharged gas from the drain port can be minimized compared to the traditional drain part with an annular space. The cooling performance dominated the dehydration ability of the three-flow vortex tube, and the largest dew point drop was 18.3 °C. Further, the largest total moisture content reduction ratio of the two exits was 61.1% at an inlet pressure of 2.0 bar and cold mass fraction of 0.45. Thus, it was demonstrated that the three-flow vortex tube with SMPM as the drain part is a potential device for gas dehydration. • A three-flow vortex tube with a SMPM as the drain part was developed. • The gas–liquid behavior within the main tube and SMPM was analyzed. • The largest φ t o t a l of the two exits was 61.1% at P in = 2.0 bar and ε = 0.45. [ABSTRACT FROM AUTHOR]

Dew point measurements for six natural gases, originating from different gas fields of the Norwegian Continental Shelf, were performed using a custom made chilled mirror apparatus. The natural gas samples were taken from different points of the Norwegian pipeline network and their composition was determined by gas chromatography. The experimental dew point data cover a temperature range from 259 to 297 K and a pressure range from 12 to 110 bar. The performance of SRK, PR, PC-SAFT and UMR-PRU models has been evaluated against the experimental data. The results indicate that the best model for hydrocarbon dew point predictions, especially at high pressures and the cricondenbar pressure, is the UMR-PRU model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design and Simulation of TSA process for C 4 + liquid recovery from high pressure natural gas stream. • TSA process followed by flue gas liquification as a more economic and alternative process of NGL recovery. • Optimization of TSA operating conditions for simultaneous NG dew point minimization and C 4 + liquid product maximization. Recovery of natural gas liquid (NGL) was investigated by temperature swing adsorption (TSA) process. The process was designed with four columns of H-type silica gel adsorbent, working in a cyclic adsorption–desorption operation of natural gas at high pressure. The NG feed composition contained 89 % methane, 1.6% C 4 + (butane and pentane), and other impurities such as CO 2 , with feed inlet weight hourly space velocity of 5.7 kgfeed/hr.kg,ads, at 85 bar pressure and 30 °C temperature. The cyclic operation was designed with three steps consisting of adsorption at high pressure, heating by purging with the hot NG at 270 °C and 25 % purge/feed ratio, followed by cooling with clean NG product from adsorption step, at the same pressure. Thereafter the regenerated heavy product from the heating step was liquified to gather C 4 + product. Modeling and simulation of this process were carried out to simulate and optimize the operating conditions with the aim of maximizing recovery of the C 4 + liquid product and minimizing outlet NG dew point. The required model parameters were evaluated by the experimental studies at the static and dynamic conditions and fitting to the proper isotherm and kinetic models, respectively. As the results of the process optimization, the fraction of C 5 in the light NG product was reduced from 0.7 % to 0.1 % and the fraction of C 4 was decreased from 0.9 % to 0.4 %. By this process the light NG product dew point was reduced from −9.5 to −58 °C and the molar fraction of C 4 + in the liquid product was reached to 43.5 %, whereas it was only 1.6 % in the initial 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]

In this study, to adjust the dew point of natural gas, two methods of Joule-Thomson and mechanical refrigeration have been analyzed in terms of technical, energy and exergy. The basis of design was a natural gas feed with an intensity of 1743 kgmole/h. The initial dew point of the feed before processing was equal to 9.65 °C. Comparison of the results showed that the mechanical refrigeration method had much better performance and the energy efficiency in this system was 99.84%, while this value was 97.8% for the Joule-Thomson method. Furthermore, the intensity of gas condensate production, as one of the products of dew point adjustment unit, for mechanical refrigeration that uses propane refrigerant for natural gas refrigeration was estimated as 1842 barrels/day. This value exhibited an increase of 185% compared to Joule-Thomson method. The dew points of produced gas through Joule-Thomson and Mechanical refrigeration processes were −8.4 and −24.91 °C, respectively. It implies that the quality of hydrocarbons dew point in the produced gas was much lower for Joule-Thomson unit compared to mechanical refrigeration. However, in terms of exergy analysis, the mechanical refrigeration method had an efficiency of 88.69%, while the exergy destruction rate for this method was 15.78% less than the Joule-Thomson process. • Simulation of Jules Thomson and mechanical refrigeration processes conducted by Aspen HYSYS. • The energy efficiencies of Jules Thomson and Mechanical Refrigeration were 97.8 and 99.84%, respectively. • Gas condensate production rate, for mechanical refrigeration exhibited an increase of 185% compared to Jules Thompson method. • Gas produced by the Joules Thomson and Mechanical refrigeration processes had dew points of -8.4 and -24.91°C, respectively. • Exergy efficiency of mechanical refrigeration was 88.69%, and its exergy degradation rate was 15.78% less than Jules Thomson. [ABSTRACT FROM AUTHOR]

Raw natural gases are frequently saturated with water during production operations. It is crucial to remove water from natural gas using dehydration process in order to eliminate safety concerns as well as for economic reasons. Triethylene glycol (TEG) dehydration units are the most common type of natural gas dehydration. Making an assessment of a TEG system takes in first ascertaining the minimum TEG concentration needed to fulfill the water content and dew point specifications of the pipeline system. A flexible and reliable method in modeling such a process is of the essence from gas engineering view point and the current contribution is an attempt in this respect. Artificial neural networks (ANNs) trained with particle swarm optimization (PSO) and back-propagation algorithm (BP) were employed to estimate the equilibrium water dew point of a natural gas stream with a TEG solution at different TEG concentrations and temperatures. PSO and BP were used to optimize the weights and biases of networks. The models were made based upon literature database covering VLE data for TEG–water system for contactor temperatures between 10 °C and 80 °C and TEG concentrations ranging from 90.00 to 99.999 wt%. Results showed PSO-ANN accomplishes more reliable outputs compared with BP-ANN in terms of statistical criteria. [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]

Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150–200 °C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50–60 °C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural gas boilers for applications with process fluid return temperatures higher than or close to the dew point of the water vapor in the flue gas. [ABSTRACT FROM AUTHOR]

Energy gases are mainly composed of methane, and they are dried prior to pumping to natural gas grids. To avoid condensation of water-vapor related problems, the dew-point temperature is monitored. In dew-point temperature measurements, however, the water-vapor enhancement factor is needed to correct effects caused by pressure changes and to enable unit conversions when using instruments based on indirect measurement principles. In the work reported in this paper, new experiments were carried out, and methane-water equilibrium data available in the literature were analyzed for deriving a new equation. The derived equation provides an easy calculation method for the water-vapor enhancement factor in methane as a function of pressure and dew-point temperature. An uncertainty analysis for the equation is also presented covering the whole studied pressure ranging from atmospheric pressure up to 7 MPa, and the dew-point temperature ranges from +20 $$^{\circ }$$ C down to hydrate forming temperatures. [ABSTRACT FROM AUTHOR]

Triethylene glycol (TEG) is one of the most effective sorbents for natural gas dehydration. There are many processes using this approach but none of them can combine high performance and economical energy consumption. In this study hydrocarbon-water phase behavior was investigated for different TEG concentrations in different natural gas dehydration processes. The equilibrium correlations were investigated for predicting water dew point as a function of TEG concentration. The effect of TEG concentration on the outlet gas dew point was also determined using phase envelope diagrams. The results showed that the (DRIZO) process achieved the most significantly reduces water dew point followed by conventional stripping gas dehydration process. Moreover, TEG was modified using potassium formate as additive. The results showed that the absorption capacity of the modified TEG was improved, that is almost duplicated. This modification augments the performance of the proposed mixture which can be potentially applied to a real scale process. [ABSTRACT FROM AUTHOR]

Condensate field controls dew point of natural gas through dehydration and de-hydrocarbons by throttling refrigeration. In the middle and late period, due to the decreasing of gas field pressure year by year, the gas cannot meet the specification of hydrocarbon dew point of natural gas. The results of HYSYS simluaiton and process comparison show that the technology of "pressurization in front of throttle valve + dehydration and dehydrocarbons by propane refrigeration" can meet the requirements of dew point. [ABSTRACT FROM AUTHOR]

The depletion of higher alkanes from methane is a key aspect during the conditioning of natural gases or accompanying gases. Membrane technologies could be used as alternative to energy and cost intensive purifications. Against this background the influence of membrane geometry, composition of the gas mixture as well as temperature and pressure was investigated in separation experiments for methane/ n-butane mixtures using MFI membranes. [ABSTRACT FROM AUTHOR]

Abstract: Dew point measurements for six synthetic natural gas (SNG) mixtures were performed using a custom made chilled mirror apparatus. The experimental data cover a temperature-range from 253 to 285K and a pressure-range from 3 to 105bar. The recently developed UMR-PRU model was revised and applied to these experimental data as well as to other dew point data for synthetic and two real natural gas mixtures reported in the literature. The results of the UMR-PRU model were compared to those obtained by the Peng–Robinson equation of state coupled with the classical van der Waals one fluid mixing rules using either zero interaction parameters or temperature dependent ones utilized in a predictive version of the PR EoS, the so-called PPR78 EoS. [Copyright &y& Elsevier]

The article presents abstracts of papers on chemical engineering of oil and gas, including a traceable calibration procedure for hydrocarbon dew point chilled mirror instruments and research direction and challenges facing the natural gas purification technology.

Current calibration procedures for hydrocarbon dew point chilled mirror instruments lack traceability. Since cross border transport of natural gas through the grids of various network operators has become general practice, the necessity for the un ambiguous determination of hydrocarbon dew point of a natural gas rises. In this paper, it will be shown that the direct relationship exists between hydrocarbon dew point and liquid drop-out content can be used for the calibration of hydrocarbon dew point chilled mirror instruments. For the first time it is now possible to calibrate a hydrocarbon dew point analyser traceable using the ISO 6570 standard. After calibration and adjustment, the measured hydrocarbon dew points of the instrument will correspond to a given potential hydrocarbon liquid content(PHLC) at the same pressure. The calibration method is described in detail in ISO technical report ISO/TR12148. The results of this work can be considered as the first step in the process towards a harmonized measuring method for the hydrocarbon dew point and thus to improved interoperability at cross border points. [ABSTRACT FROM AUTHOR]

The hydrocarbon dew point (HCDP) of natural gas is a key parameter in the gas transportation industry. Predicting and calculating HCDP precisely can ensure the security and reliability of the system. This article begins with an introduction of the methods to predict and measure HCDP and determines a suitable equation of state model to calculate HCDP of natural gas from the West to East-I pipeline. The natural gas composition is analyzed by an on-line gas chromatograph and an extended analysis in the laboratory. Based on the results computed by TPCOMP,1 the influence of natural components to calculate HCDP is discussed, and a modified method to add 0.0002-0.0004% up to the heaviest hydrocarbon is proposed to make the agreement within ±3°C between calculation and measurement. [ABSTRACT FROM AUTHOR]

Abstract: The applicability of the recently developed UMR-PRU EoS/G E model is extended in this work by evaluating new gas containing UNIFAC group interaction parameters. Satisfactory prediction of various types of VLE data (dew and bubble point pressures, equilibrium ratios, liquid drop out, etc.) of multi-component systems, including gas condensates and oil mixtures, is obtained, and it is comparable or better than that of the other two EoS/G E models considered, the LCVM and the PSRK. It is concluded that the UMR-PRU model is a powerful tool for phase equilibrium predictions in mixtures of interest to the gas and oil industry. [Copyright &y& Elsevier]