Thermodynamic Properties of Synthetic Natural Gases. Part 3. Dew Point Curves of Synthetic Natural Gases and Their Mixtures with Water. Measurement and Correlation (original) (raw)
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Energy & Fuels, 2002
Dew points for two synthetic natural gas (SNG) mixtures between 1.2 × 10 5 and 81.8 × 10 5 Pa in the temperature range from 213.6 to 261.4 K, four SNG + water mixtures between 1.1 × 10 5 and 41.0 × 10 5 Pa and temperatures from 244.7 to 288.1 K, and four SNG + water + methanol mixtures between 1.1 × 10 5 and 20.7 × 10 5 Pa and temperatures from 247.6 to 288.6 K were experimentally determined. The experimental results obtained on the multicomponent systems were analyzed in terms of a predictive excess function-equation of state (EF-EOS) method, which reproduced experimental dew point temperature data with absolute average deviation (AAD) between 0.9 and 3.1 K for the dry systems, from 0.0 to 1.6 K for the systems with water, and from 0.0 to 3.0 K for the systems with water and methanol. The experimental results obtained for synthetic natural gas (SNG) + water mixtures at pressure values higher than 5 × 10 5 Pa were also compared to a predictive equation of state (EOS) model. It reproduced experimental dew point temperature data within AAD between 1.8 and 5.3 K.
Measurement and prediction of dew point curves of natural gas mixtures
Fluid Phase Equilibria, 2012
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 285 K and a pressure-range from 3 to 105 bar. 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.
Industrial & Engineering Chemistry Research, 2006
Dew points have been measured for binary propane or n-butane + carbon dioxide mixtures at pressures from 1.2 × 10 5 to 34.9 × 10 5 Pa and temperatures from 192.6 to 274.8 K, four ternary propane or n-butane + carbon dioxide + water mixtures from 1.1 × 10 5 to 20.7 × 10 5 Pa and temperatures from 247.5 to 289.0 K, and eight quaternary propane or n-butane + carbon dioxide + water + methanol mixtures from 1.1 × 10 5 to 21.8 × 10 5 Pa and temperatures from 249.8 to 289.9 K. The results are analyzed in terms of a predictive EF-EOS excess-function equation of state method based on the zeroth-approximation of Guggenheim's reticular model. This method has been chosen because it can be used to adequately predict the dew points of all the mixtures of our interest in the dew temperature and pressure ranges. In fact, the model reproduces the experimental dew-point temperature data within an AAD (absolute average deviation) of 1.6 and 1.3 K for the binary systems, between 0.1 and 2.5 K for the ternary systems, and between 0.0 and 5.1 K for the quaternary systems. The experimental results obtained for ternary propane or n-butane + carbon dioxide + water mixtures at pressure values higher than 5 × 10 5 Pa were also compared to a predictive EOS (equation of state) model. It reproduced experimental dew-point temperature data within AAD between 0.0 and 5.5 K.
Energy & Fuels, 2004
Experimental measurements of dew points for seven methane + carbon dioxide + water mixtures in the pressure range of 1.1 × 10 5 -60.5 × 10 5 Pa in the temperature range of 243.1-288.1 K, and four ethane + carbon dioxide + water mixtures at pressures of 1.1 × 10 5 -20.3 × 10 5 Pa and temperatures of 252.2-288.4 K, were determined. The experimental results obtained on the ternary systems were analyzed in terms of a predictive excess function-equation of state (EF-EOS) method, which reproduced experimental dew-point temperature data within an absolute average deviation (AAD) of 0.1-2.1 K. The experimental results obtained for the studied mixtures at pressures of >5 × 10 5 Pa were also compared to a predictive equation of state (EOS) model. It reproduced experimental dew-point temperature data within AAD values of 0.9-2.1 K.
Dew points of binary carbon dioxide + water and ternary carbon dioxide + water + methanol mixtures
Fluid Phase Equilibria, 2004
Dew points for four carbon dioxide + water mixtures between 1.2 × 10 5 and 41.1 × 10 5 Pa in the temperature range from 251.9 to 288.2 K, and eight carbon dioxide + water + methanol mixtures between 1.2 × 10 5 and 43.5 × 10 5 Pa and temperatures from 246.0 to 289.0 K were experimentally determined. The experimental results obtained on the binary and ternary systems were analysed in terms of a predictive excess function-equation of state (EF-EOS) method, which reproduced the experimental dew point temperature data with absolute average deviation (AAD) between 0.8 and 1.8 K for the systems with water, and from 0.0 to 2.7 K for the systems with water and methanol. The experimental results obtained for carbon dioxide + water mixtures, with molar fraction of water lower than 0.00174, at pressure values higher than 5 × 10 5 Pa were also compared to a predictive equation of state model. It reproduced experimental dew point temperature data with AAD between 0.2 and 0.6 K.
Water is probably the most undesirable component found in crude natural gas because its presence can produce hydrate formation, and it can also lead to corrosion or erosion problems in pipes and equipment. Natural gas must be dehydrated before being transported through a long distance to ensure an efficient and trouble-free operation. Thermodynamic modelling of triethyleneglycol (TEG)-water system is still rather inaccurate, especially with regard to systems at high temperature and high TEG concentration. As a consequence, design and operation of absorber towers are affected by the lack of accurate data. Two novel correlations have been developed to estimate the equilibrium water dew point of a natural gas stream by evaluating experimental data and literature. These data were collected and analyzed by means of images scanned with MATLAB software R2012B version. An average percentage error is of 1-2% for linear correlation and it is of 2-3% for non-linear correlation. Results are quite accurate and they are consistent with literature data. Due to the simplicity and precision of the correlations developed in this work, the equations obtained have a great practical value. Consequently, they allow process engineers to perform a quick check of the water dew point at different conditions without using complex expressions or graphics.
Evaluation of the physical dew point in the economizer of a combined cycle burning natural gas
Applied Thermal Engineering, 2007
Natural gas contents a considerable percentage of hydrogen, so is obvious to expect an amount of water vapour in its combustion exhaust gases, which would raise the dew point temperature. That means a higher speed of corrosion over the whole exposed physical area, which could represents a serious risk of breakdown, especially in pressurized hot-water equipments. In this work, a new methodology for determining the physical dew point inside a economizer depending on the fuel type burned (in this case is natural gas) has been developed. The calculation of the total amount of condensed water has also been carried out as well as the localization of the area where this condensation occurs. Acid dew point has not been taken into account here although exhaust gases are acidic, due mainly to the low sulphur content which is almost undetectable when burning natural gas, but it will be performed in a later study coming soon.
A new Peng-Robinson modification to enhance dew point estimations of natural gases
Journal of Natural Gas Science and Engineering, 2016
Equations of state (EOSs) are widely used in calculations such as those involving reservoir simulation, process simulation, gas processing and transportation of natural gas. Predicting the phase envelope, specifically the dew points of natural gas, is among the important roles of EOSs. In this study, a modification is proposed to improve the predictions of dew point properties by the Peng-Robinson (PR) EOS, where the attraction parameter has been modified by a new empirical-based coefficient which is a function of reduced pressure, reduced temperature and critical density. In order to validate the modification, results are presented for four major properties of dew points consisting of the cricondentherm, cricondenbar, dew point temperature and dew point pressure. Furthermore, the performances of the original PR, Soave-Redlich-Kwong (SRK), Schmidt-Wenzel (SW) and GERG-2008 EOSs, have been compared to predict the above four properties with respect to the experimental data. Having similar qualitative trends for the four properties, the results show that the modification of this study gives better predictions of the dew point curves, followed by the GERG EOS, which was developed particularly for processed natural gases. The SRK and SW EOSs have comparatively similar results and the PR EOS has the largest deviations.
Densities and mixture virial coefficients for wet natural gas mixtures
Journal of Chemical & Engineering Data, 1987
Experimental densities plus second and thlrd mixture vlrlal coefflclents are reported for two well-defined natural gases, one sweet and one sour, wlth varylng amounts of water vapor to 10% (mole basls). The Burnett-lsochorlc densities, which range from 50 to 210 O C and 0.1-16.9 MPa, are preclse to fO.O1% and are considered accurate to f0.04%. I ntroductlon Few experimental measurements exist for the density of wet (water containing) natural gas mixtures in the temperature range from 50 to 210 O C at pressures to the dew point. Comprehensive and accurate densities over a range of temperature, density, and water level are necessary to test equation of state (EOS) predictions used by the natural gas industry. Our present sweet and sour dry gases were selected to represent those natural gases found in practice. Composltlon of Dry Natural Gases Tables I and I 1 contain the composition of the dry, sweet gas and the dry, sour gas, respectively. Both gases were obtained from the Phillips Petroleum Co. The sour gas decompositiin disclaimer published by Phillips at the bottom of Table I 1 was not a serious consideration. Periodic chromatographic analyses indicated no significant decomposition of the sour gas in the original cylinder, even after 2 years. Because water is simply added to the dry gas (sweet or sour) to make up the wet gas mixtures, the composition of our 5 mol % waterlsweet gas, for example, is 5 mol % water plus 95 mol % dry, sweet gas or 0.95 is multiplied by the mole percentages of Table I to obtain the mole percent of each dry gas component in the wet gas mixture. Experlmental Apparatus The Burnett-isochoric (B-I) density apparatus was described previously by Mansoorian et al. (1) and Eubank et al. (2). A complete description of the apparatus and experimental techniques may be found in the dissertation of Scheloske (3). Water was weighed before mixing with the natural gas in a variation of the Burnett mixing method of ref 2. Because the water content dM not exceed 10% (mole basis), the usual adsorption diagnostics (4) were negative even for the sour gas mixtures. That is, the limiting pressure ratio (or apparatus constant) on a Burnett isotherm was the same as for helium at the same temperature. Results The experimental dew point pressures and enthalpy residuals for these same systems have been published previously (5). A
Optimum operating conditions for improving natural gas dew point and condensate throughput
Journal of Natural Gas Science and Engineering, 2018
Natural gas dew point temperature is a vital quality parameter. The effective control of this specification is important if the natural gas integrity and quality are to be maintained. The present work focuses on improving the dew point and condensation production rate of south Dabaa field dew point control unit (DPCU) located in the Egyptian western desert and owned to the South Dabaa Petroleum Company. Influence of the operational variables on outlet gas dew point and produced condensate were investigated. The simulation results illustrated that feed gas inlet temperature, composition and flow rate, Joule Thomson (JT) valve downstream, and upstream pressure and hot bypass flow rate have a great effect on the sales gas dew point as well as the condensate throughput. A field experiments were conducted to validate the simulation results. It is noticed that there is a good agreement between simulation and experimental results, considering the outlet gas dew point at different operating conditions. Lingo optimization software was used to find the plant optimum conditions. Two quadratic equations were developed based on regression analysis for calculating the dew point and plant condensate rate at any operational variables. The impact of replacing the existing JT valve by a turbo expander was studied. The simulation results indicate that the turbo expander is more effective in comparison with JT valve refrigeration system in decreasing the sales gas dew point and increasing the condensate production rate.