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Vegetable oils are non-toxic and biodegradable and are gaining attention as replacements for toxic antifoam and defoamer formulations in the oil and gas industry. Severe foaming may occur at the water wash section of natural gas treatment units resulting in low gas purification. This study evaluated some vegetable oils' physical and compositional properties as suitable substitutes in antifoam/defoamer formulations. Vegetable oils were extracted from palm kernel, coconut, soya bean, groundnut, castor nut, tiger nut, pecan nut, and walnut using the Soxhlet extraction method. Extracted oils were analyzed for percentage oil recovery, peroxide value, viscosity, specific gravity, percentage free fatty acid (FFA), iodine value, and saponification value and compared with two commercial defoamers. The results showed that coconut, walnut, and palm kernel gave significantly higher oil recoveries of 54, 52, and 50%, respectively. Percentage FFA in castor oil, pecan oil, and walnut oil was considerably higher at 7.40, 5.80, and 5.2%, respectively. Coconut and palm kernel oil had lower iodine values of 9.54 and 18.85g/100g and saponification values of 54.65 and 72.44mgKOH/g, respectively. The viscosity of palm kernel and coconut oils at 30 °C compared well with one of the commercial defoamers. At 55 °C, palm kernel, coconut, and groundnut oil gave a significantly low viscosity of 5.27, 3.7, and 0.95cSt. The specific gravity and pH of all the oil samples were similar to those of the commercial defoamers. From the analysis of the results, coconut and palm kernel oils were found to have better antifoam and defoamer properties than the other oils. As such, they are suitable for use in antifoam/defoamers formulations. [ABSTRACT FROM AUTHOR]

Mercury will enter into each process mass flow unit during natural gas treatment . Mercury would not only be volatile to the environment and harm to the health of the staff, but also cause mercury corrosion and noble metal catalyst poisoning in the product ion equipments. In this paper, VMGSim simulation software was used to simulate and analyze the whole natural gas processing and it was found that mercury in natural gas mainly entered into ethylene glycol rich solution, wastewater from the top of regeneration tower, and stable condensate oil. which had guiding significance for mercury pollution control in subsequent treatment plant. Through analyzing the composition of feed gas, feed temperature of cryogenic separator, and the content of ethylene glycol, it was found that the increase of light hydrocarbon in feed gas was beneficial to the absorption of mercury by ethylene glycol, and the decrease of the mass fraction of ethylene glycol would promote the desorption of mercury by ethylene glycol rich liquid. From the perspective of environmental protection and safety, the prevention and control measures of mercury pollution in the main units of the whole natural gas processing plant were put forward. [ABSTRACT FROM AUTHOR]

Aiming at the problems of excessive H,S content in wet purified gas and tot al sulfur content in liquefied gas and low C, yield in an associated gas treatment unit in Tahe oilfield, the integrated process of H, S and organic sulfur removal from associated gas was innovated and applied based on sour gas atmospheric absorption experiment, which uses CDS compo und amine solution to remove H, S and organic sulfur simultaneously in same unit. In addition, the effect of nat ural gas treatment was improved by adding propane cooler and high-efficiency cyclone separator for feed gas and optimizing the parameter control logic of MDEA regeneration syst em. After revamping, the H, S mass concentration in \Vet purified gas was reduced from '12-197 mg/m³ to 16-23 mg/m³, the total sulfur mass concentration in LPG was reduced by 90%, the yield of C, increased to more than 90%, the daily average output of LPG and stable light hydrocarbon increased by l·L 3 t and /1. 6 t respectively, and the annual direct economic benefit was up to 20 million yuan. [ABSTRACT FROM AUTHOR]

In the process of natural gas dehydration in a light hydrocarbon station of Northwest Oilfield Branch of Sinopec, molecular sieve three-tower process was adopted. During the initial stage of cold blowing, the exit temperature increased and the regeneration rate was faster. For this reason, after eliminated the equipment failure, sulfite was detected in the waste water sample from regenerated gas water separator, and combined with the results of XRF element content detection of gas sample, the essential reason of molecular sieve failure and temperature rise was that the oxygen content in the feed gas of the station was too high, which caused a series of chemical reactions among iron, oxygen and hydrogen sulfide in the drying tower and released heat. Based on above reasons, corresponding measures were taken to break the environmental conditions required for chemical reactions, consequently resuming the normal production. The operation experience of the unit could provide reference for the design and normal operation of similar units. [ABSTRACT FROM AUTHOR]

Abstract In this study, we report on the effects of Ag+ cations exchange within clinoptilolite zeolite in relation to both the physicochemical and the gas adsorption characteristics. Clinoptilolites cation-exchanged with AgNO 3 to varying degrees were investigated and the influence of naturally occurring cations (Mg2+, Ca2+, K+) distributed within the material is discussed. The morphology and elemental composition of the untreated clinoptilolite and the Ag+ cation exchanged variants were characterized by XRD, EDS, FTIR, and N 2 sorption experiments performed at 77 K. From the pore property analysis, we show that a slight reduction in the micropore distribution occurs for the highly exchanged Ag+ clinoptilolite compared to the untreated clinoptilolite, indicating a likely decrease in the average effective micropore size. Equilibrium adsorption isotherms of CH 4 and N 2 were measured at 303 K. The adsorption uptake rate of both gases was also studied and it slowed by the addition of Ag+ cations. The modified samples showed decreasing adsorption capacity for the larger CH 4 gas molecule, whereas adsorption of the smaller N 2 gas was less affected. This effect was most pronounced for the highly exchanged Ag+ clinoptilolite samples (AgNO 3 exchange solution above 0.2M) whereby more N 2 was adsorbed than CH 4. At 1 atm and 303 K, the N 2 /CH 4 equilibrium selectivity values of highly exchanged Ag+ clinoptilolite ranged from 2.8 to 7.6, which are higher than many clinoptilolite types. Graphical abstract Image 1 Highlights • Natural clinoptilolite displays increased N 2 /CH 4 equilibrium selectivity following exchange with Ag+ cations. • Reduced CH 4 equilibrium adsorption capacity resulting from pore blocking in the Ag+ exchanged clinoptilolite is observed. • Higher microporous diffusion resistance for Ag+ clinoptilolite compared to natural clinoptilolite. [ABSTRACT FROM AUTHOR]

Hydroquinone (HQ) clathrates have recently been identified as promising candidates for selective gas capture and storage processes. This study evaluates the effectiveness of HQ clathrates in the separation of CO 2 from CO 2 /CH 4 gas mixtures, through direct gas/solid reactions in a fixed-bed reactor. The influence of the process operating parameters (i.e. reaction time, pressure, temperature and feed gas composition) on the CO 2 capture kinetics, selectivity towards CO 2 , and transient storage capacity were investigated. The experiments were performed using either pure HQ or HQ-based composite materials, with temperatures ranging from about 283 to 343 K, pressures from 3.0 to 9.0 MPa, and CO 2 mole fraction in the gas mixture ranging from 0.2 to 1. The experimental results show that over the range of gas composition investigated, the enclathration reaction is selective to CO 2 . This preferential CO 2 capture is enhanced at high CO 2 mole fractions, low temperatures and high pressures. Regarding gas capture kinetics, it was confirmed that the composite material is much more efficient than pure HQ crystals. The CO 2 enclathration rate increases with temperature, pressure and CO 2 fraction in the feed gas. For the first time, the feasibility of such gas separation techniques using HQ clathrates was demonstrated at bench scale. [ABSTRACT FROM AUTHOR]

Reservoir gas treatment technologies currently in use require significant investments in equipment and materials. Considering the foregoing, new technologies are sought for treatment and separation of components of extracted gas. They will guarantee compliance with gas quality requirements arising from applicable standards while at the same time lowering the costs of investment, service and environmental protection. Therefore, the purpose of this work was to develop an efficient mobile technology for natural gas treatment, on the basis of advanced filtering and coalescing materials and membranes, which eliminate the existing, economically non-viable processes and reduce the costs related to development of new reservoirs. The purpose of designed materials was removal of solid particles, water, higher hydrocarbons and nitrogen from natural gas. Presented integrated filtration and membrane system, characterized by a highly compact design enabling installation in container stations and transporting the system between specific points of production. [ABSTRACT FROM AUTHOR]

Functionalized copolyimides continue to attract much attention as membrane materials because they can fulfill the demands for industrial applications. Thus not only good separation characteristics but also high temperature stability and chemical resistance are required. Furthermore, it is very important that membrane materials are resistant to plasticization since it has been shown that this phenomenon leads to a significant increase in permeability with a dramatic loss in selectivity. Plasticization effects occur with most polymer membranes at high CO2 concentrations and pressures, respectively. Plasticization effects are also observed with higher hydrocarbons such as propylene, propane, aromatics or sulfur containing aromatics. Unfortunately, these components are present in mixtures of high commercial relevance and can be separated economically by single membrane units or hybrid processes where conventional separation units are combined with membrane-based processes. In this paper the advantages of carboxy group containing 6FDA (4,4′-hexafluoroisopropylidene diphthalic anhydride) -copolyimides are discussed based on the experimental results for non cross-linked, ionically and covalently cross-linked membrane materials with respect to the separation of olefins/paraffins, e.g. propylene/propane, aromatic/aliphatic separation e.g. benzene/cyclohexane as well as high pressure gas separations, e.g. CO2/CH4 mixtures. In addition, opportunities for implementing the membrane units in conventional separation processes are discussed.

Our previously reported high pressure hollow fibers membrane (HFM) modules were specifically developed with aim to meet the operation requirements for the industrial sweetening of natural gas. The present work presents further characterization of CO 2 and H 2 S high pressure removal under different experimental conditions, which are in particular relevant to the ultimate intended industrial application. These include module packing density, feed gas/absorption liquid flow rate ratio, absorption liquid temperature as well as solvent loading. The operational stability of the HFM module, equipped with the PFA hollow fibers, was also investigated and reported. The presented results on the long-term operational stability of membrane modules based on hollow fibers, under industrially relevant conditions are believed to be the first report of its kind. The PFA-HFM modules showed excellent operational stability during the test period, i.e., ∼200 operation hours over a 7-week period using pressurized feed gas pressure (50 bar) and hot absorption solvent (100 °C). [ABSTRACT FROM AUTHOR]

In this paper we review research progress on metal organic framework membranes which have demonstrated ability to separate carbon dioxide from different light gases. More specifically, we focus mainly on CO 2 /N 2 , CO 2 /CH 4 , and CO 2 /H 2 , gas separations which are highly relevant compositions in flue gas treatment, natural gas purification, and hydrogen purification, respectively. We also discuss several conventional and novel strategies developed by several research groups for the continuous defect-free MOF membrane fabrication. Finally, the advantages of using MOFs in mixed matrix membranes and improvements in gas separation performances with the MOF based mixed matrix membranes are presented. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work is to study in detail the sorption of binary gas mixtures containing methane into polymers suitable for membrane separations. A novel measuring procedure has been developed and validated by performing mixed gas sorption tests on the n-C4/CH4 mixture in films of poly(1-trimethylsilyl-1-propyne) (PTMSP), for which literature data are available. Then, individual uptakes of CH4 and CO2 from binary gas mixtures were measured at 35°C and up to 35bar in PTMSP, in the whole gas composition range. The experiments were conducted on a pressure-decay apparatus equipped with a gas chromatographic device. The novel experimental procedure was set up in order to obtain data either at constant partial pressure of one gas, as done by previous authors, or at constant gas composition and variable total pressure. The latter protocol allows to mimic more closely the real membrane separation processes, where only the total pressure of the mixture can be varied arbitrarily. It was observed that the presence of CH4 does not alter significantly the sorption of CO2 and of n-C4 in PTMSP, while the mixed gas solubility of CH4 is lower than the pure gas value at the same CH4 fugacity. In particular, the CH4 solubility coefficient, as well as the mixed gas solubility selectivity are univocal functions of CO2 fugacity (or concentration) and are otherwise independent of the gas phase composition. The real CO2/CH4 solubility-selectivity of PTMSP is similar to the ideal value at low CO2 fugacity but it becomes significantly higher, up to 4.5 times, at 25bar of CO2 fugacity. A quantitative rule can be drawn using data of several binary gas mixtures in glassy polymers, based on which the ratio between actual mixed gas and pure ideal solubility selectivity of CO2 over CH4 is a single, monotonously increasing function of the ratio between the concentration of the two components, c(CO2)/c(CH4), which becomes higher than unity as c(CO2)>c(CH4). In other words, the competition effects depress more significantly the less abundant penetrant in the polymer, that is usually CH4. [Copyright &y& Elsevier]

This paper firstly analyzes the influences of low load condition on natural gas treatment unit from two aspects: the low load condition can lead to surging, as well as yield decline, which directly affects the economic benefits. Secondly, aiming at the harm of units at low load condition, according to the experience formula of expansion refrigeration and throttling expansion, the methods, such as improving the processing capacity, the expansion ratio of expansion machine, and the throttle effect, and increasing the auxiliary refrigerating capacity, etc, are used to reduce top temperature of methane tower, so as to improve the unit yield. These measures have certain reference significance to the operation of similar natural gas treatment plant. [ABSTRACT FROM AUTHOR]

Being a discrete-continuous process, approach to a cyclic steady state in computer simulation of Pressure Swing Adsorption is through iterative procedures and simulation itself is quite computation-intensive. Considering the fact that simulation based design itself is an iterative process, it is imperative that simulation be computationally very efficient and phenomenologically as close to the physics of adsorption-desorption as possible. Utility of lumping the components of a gas mixture into fewer pseudo-components was computationally examined in the simulation of a representative multi-step cycle of a pressure swing based adsorptive separation process applied to natural gas treatment. The actual feed had six components competing for adsorbent sites. Five different lumping alternatives were studied and compared with the simulation results for a full six-component simulation under identical equipment dimensions and operating conditions. Lumping could reduce the number of equations to be solved by more than half and the corresponding reduction in CPU time was about 90%. The six component mixture of Natural Gas was found to be sufficiently represented by two pseudo-components. The predicted recovery (in terms of Methane and Ethane) and quality (in terms of content of higher hydrocarbons) of the raffinate differed by not more than 0.8% and 0.02% respectively. The paper discusses possible heuristics for decision-making regarding appropriate lumping as verified by extensive simulation studies. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to find out the optimum configuration and design variables for the asymmetric membrane-based separation of carbon dioxide from natural gas for meeting the pipeline specification of 2% carbon dioxide. For this purpose, optimization of gas processing cost of the membrane unit having up to three stages is performed based on a fundamental model of the unit. It shows that there is no unique configuration that is always optimum irrespective of the values of carbon dioxide concentration and natural gas price. However, within certain ranges of the carbon dioxide concentration and the natural gas price, the optimum configuration may be unique and the minimum gas processing cost can be achieved by adjusting only the number of modules in each stage and the compressor power. In most cases, there is no significant cost difference between the two and three staged optimum configurations and the choice of a configuration may depend on engineering assessment. [Copyright &y& Elsevier]