An optimal control framework to determine diffusivity versus concentration surfaces in ternary systems of two gases and a non volatile phase

Diffusivity is a strong function of concentration and an important transport property. Diffusion of multiple species is far more frequent than the diffusion of one species. However, there are limited experimental data available on multi-component diffusivity. The objective of this study is to develop an optimal control framework to determine multi-component concentration-dependent diffusivities of two gases in a non-volatile phase such as polymer. In Part 1 of this study, we derived a detailed mass-transfer model of the experimental diffusion process for the non-volatile phase to provide the temporal masses of gases in the polymer. The determination of diffusivities is an inverse problem involving principles of optimal control. Necessary conditions are determined to solve this problem. In Part 2 of this study, we utilized the results of Part 1 to determine the concentration-dependent, multi-component diffusivities of nitrogen and carbon dioxide in polystyrene. To that end, solubility and diffusion experiments are conducted to obtain necessary data. In the ternary system of nitrogen (1), carbon dioxide (2), and polystyrene (3), the diffusivities and D11, D12, D21, and D22 versus the gas mass fractions are two-dimensional surfaces. The diffusivity of carbon dioxide was found to be greater than that of nitrogen. The value of the main diffusion coefficient D11 was found to increase as the concentration of carbon dioxide increased. The highest value of D11 obtained was 2.2 X 10^-8m^2s^-1 for nitrogen mass fraction of 3.14 X10^-4 and for a carbon dioxide mass fraction of 5.67 X 10^-4 . The cross-diffusion coefficient increased as the concentrations of nitrogen and carbon dioxide increased. The diffusivity reached its maximum value when the concentrations of nitrogen and carbon dioxide were at their maximum values. The diffusivity was of the order of 10^-9m^2s^-1. The diffusivity of the cross-diffusion coefficient D21 was found to be increased for the mass The diffusivity of the cross-diffusion coefficient was found to be increased for the mass fractions of carbon dioxide ranging from 0 to 1.70 X 10^-3 . The diffusivity was found to be of the order of . The diffusion coefficient, D22, was found to increase with the concentrations of nitrogen and carbon dioxide, D22 remained high with low concentrations of carbon dioxide. The diffusivity was found to be of the order of 10^-7m^2s^-1

Characteristics of the large-scale circulation during episodes with high and low concentrations of carbon dioxide and air pollutants at an arctic monitoring site in winter

The rapid growth of Carbon Dioxide (CO2) and/or Nitrogen (N2) Enhanced Oil Recovery (EOR) projects has resulted in the need for efficient low cost rejection technology. This is particularly true if the Nitrogen or Carbon Dioxide is produced with a natural gas that has an existing market. Basic rejection cycles are described and compared. Key process and mechanical design considerations, especially those unique to Nitrogen and Carbon Dioxide, are emphasized. The Carbon Dioxide or Nitrogen content in the produced gas increases with time over the life of a project, so the rejection equipment must perform satisfactorily over a broad range of feed compositions. Recycling the rejected Carbon Dioxide or Nitrogen is a cheaper source of injection gas than its original source. A rejection unit can be designed as an add-on unit to existing natural gas processing facilities in which much of the stabilization, pre-treatment, and liquid recovery already exists. A sample application for nitrogen rejection is presented including process performance and simple economics for a "typical" case.

SUMMARYFive experiments are described which were designed to investigate the effects of varying the concentrations of nitrate, phosphate, potassium and carbon dioxide in the culture solution on the morphology and vegetative reproduction of Sphagnum cuspidatum Ehrh. The plants were grown axenically from spores sown on agar containing inorganic salts and then transferred to aqueous culture solutions through which air containing enhanced concentrations of carbon dioxide was passed.In three of the experiments the plants were grown in a balanced inorganic salt solution at various dilutions and in two of these the concentration of carbon dioxide in the gas bubbled through the solution was varied. The concentrations of nitrogen, phosphorus and potassium were varied independently and in combination in the remaining experiments while the concentration of carbon dioxide was kept constant.In some of the experiments the minimum concentrations of nitrogen and potassium supplied were considerably below the minimum average concentrations recorded in rain but the minimum concentration of phosphorus supplied was within the upper part of the range recorded in rain. Within the ranges supplied the concentrations of all three elements and of carbon dioxide affected interfascicle length and vegetative reproduction (innovation formation) but it was concluded that the element limiting innovation formation in natural conditions is phosphorus.

Lactic acid, carbon dioxide and human sweat stimuli were presented singly and in combination to femaleAedes aegypti(Linnaeus) within a wind-tunnel system. The take-off, flight, landing and probing responses of the mosquitoes were recorded using direct observation and video techniques. The analyses determined the nature of the response to different stimuli and the concentration ranges within which specific behaviours occurred. A threshold carbon dioxide concentration for taking-off of approximately 0.03% above ambient was detected. Lactic acid and human sweat samples did not elicit take-off when presented alone, however, when they were combined with elevated carbon dioxide, take-off rate was enhanced in most of the combinations tested. Flight activity was positively correlated with carbon dioxide level and some evidence for synergism with lactic acid was found within a narrow window of blend concentrations. The factors eliciting landing were more subtle. There was a positive correlation between landing rate and carbon dioxide concentration. At the lowest carbon dioxide concentration tested, landing occurred only in the presence of lactic acid. Within a window of low to intermediate concentrations, landing rate was enhanced by this combination. At the highest carbon dioxide concentration, landing was however inhibited by the presence of lactic acid. The sweat extract elicited landings in the absence of elevated carbon dioxide. This indicated the presence of chemical stimuli, other than lactic acid, active in the short range. Probing occurred only at low carbon dioxide concentrations and there was no probing when lactic acid alone was tested. There was however probing in the presence of combined stimuli, the level of response seemed to be positively correlated with the ratio of carbon dioxide and lactic acid concentrations.

Providing for increasing global energy needs while managing carbon dioxide emissions is the dual energy challenge the modern world faces. In order to meet this challenge, reliable and dispatchable low carbon energy sources are a likely component. For many scenarios, this suggests that cost effective carbon dioxide capture will be a key technology.[1] Carbon capture with carbonate fuel cells (CFCs) may be one such technology option.[2]Carbonate fuel cells concentrate carbon dioxide from the cathode to the anode as part of their normal operation, effectively doing both carbon capture and low carbon power generation in a single process. (see Figure 1) When generating power, typical carbon dioxide concentrations fed to the CFC cathode tend to be higher than carbon dioxide emissions of many industrial processes. This means that if we want to capture that carbon dioxide, we need the fuel cell to operate at lower carbon dioxide concentrations than it typically does. For carbon capture operations, cathode inlet carbon dioxide concentrations could be as low as 4%. Additionally, under typical power generation operations, CFCs only capture a fraction of the carbon dioxide (<50%) fed to the cathode, where for carbon capture rates may be as high as 90%. Together these two constraints (low initial concentration and higher capture) results in very low carbon dioxide concentrations in the cell, particularly at the cathode outlet. This may impact the fundamental chemistry of the process. Carbon dioxide capture at 4% and lower was tested in a fuel cell, specifically designed to minimize mass transport effects external to the active cell components. Carbon capture was demonstrated at a range of carbon dioxide concentrations ranging from standard operation for power generation (>10%) to <1%. Additionally, oxygen concentrations and current densities were varied over likely operational ranges. We demonstrate that under most circumstances, operations under carbon capture conditions proceed via a similar mechanism to those under power generation conditions. However, in harsh or extreme conditions, where carbon dioxide concentrations are low (<0.5%) and/or current densities high, alternative mechanisms appear. We demonstrate how the CFC performs when these alternative mechanisms are present. Additionally, our findings suggest that they appear to utilize water in place of carbon dioxide and allow the cell to operate at conditions beyond theoretical complete carbon capture. [1] IEA World Energy Outlook 2018; Bloomberg New Energy Finance, New Energy Outlook 2018 [2] Ghezel-Ayagh H., Jolly S., Patel D., Hunt J., Steen W., Richardson C., Marina O., (2013) A Novel System for Carbon Dioxide Capture Utilizing Electrochemical Membrane Technology ECS Transaction Vol 51 (1) 265-272 Figure 1

For the design of high oxygen modified atmosphere packages, knowledge and modelling of respiration rates at both low and super‐atmospheric oxygen levels is required. Fresh‐cut butterhead lettuce was stored in glass jars at three different temperatures (1 °C, 5 °C and 9 °C), three carbon dioxide levels (0, 10 and 20 kPa) and eight different levels of oxygen partial pressures (0, 2, 5, 10, 20, 50, 70 and 100 kPa). Oxygen consumption and carbon dioxide production rates were measured. The respiration rates were significantly reduced by low temperatures and elevated carbon dioxide concentrations up to 10 kPa. At carbon dioxide concentrations of 20 kPa the respiration rates were comparable to those at 0 kPa CO2 probably due to an injury response. Oxygen concentrations had to be below 2 kPa to significantly reduce the respiration rates compared to air conditions. Respiration rates were also slightly lower under super‐atmospheric (50, 70 and 100 kPa) oxygen partial pressures than at air conditions. Additionally, a Michaelis–Menten based model to describe the respiration rates as a function of oxygen, carbon dioxide and temperature was constructed. Models that include respiration rates at super‐atmospheric oxygen levels have not previously been described. The inhibitive effects of carbon dioxide and high oxygen concentrations were incorporated by an uncompetitive and a non‐competitive inhibition term respectively. Temperature effects were described using Arrhenius' law. The model gave a good description (R2adj = 0.82) of the oxygen consumption and carbon dioxide production rates over the temperature, oxygen and carbon dioxide range tested. Copyright © 2006 Society of Chemical Industry

Measurement of carbon monoxide in simulated expired breath

The Dongfang gas field, located in a diapir structure zone, is the largest gas field found in the Yinggehai Basin. A strong thermal anomaly caused by hydrothermal fluid flows occurs in the gas field, as evidenced from drill-stem test and fluid inclusion homogenization temperatures, Rock-Eval Tmax, vitrinite reflectance, and clay-mineral transformation profiles. Such a thermal anomaly suggests focused, rapid flow of deeply sourced hydrothermal fluids, which has shifted the threshold depth to the onset of hydrocarbon generation upward by about 500 m. The Dongfang gas field shows considerable variation in nitrogen and carbon dioxide content, with nitrogen content ranging from less than 5 to 31.2% and carbon dioxide content ranging from less than 1 to 88.9%. Hydrocarbon gases and associated condensates show high maturities and have been generated most probably from the Meishan and Sanya formations of Miocene age. Carbon dioxide in gases with CO2 content less than 10% is organic in origin, whereas carbon dioxide in gases with CO2 content higher than 10% is inorganic in origin and has been generated from high-temperature decomposition of carbonates. Most gases display negative d15N values. Gases with nitrogen content higher than 15% always contain organic CO2 (CO2d13C values lighter than -10o/oo,), and the nitrogen contents decrease as the d13C values for methane and ethane become heavier, suggesting an organic origin of the nitrogen gas generated in the catagenetic stage (source rock Ro <2.0%), before the significant thermal decomposition of carbonate took place. Systematic interreservoir compositional heterogeneities occur in the gas field, which, along with the thermal regime and fluid-inclusion homogenization-temperature measurements, give a clear suggestion of the reservoir-filling history: methane-dominated gases with relatively high nitrogen content and a small amount of organic CO2 accumulated first, and carbon dioxide-rich gases with hydrocarbon components of higher maturity injected into the reservoir later. Interreservoir compositional heterogeneities, which have the advantage of being unaffected by in-reservoir mixing processes, can be effective indicators of the field-filling history, especially when they are studied in combination with fluid-inclusion and reservoir-diagenesis analyses. The short-lived, transient nature of the thermal effect of fluid flow and the wide variation of the toluene/n-heptane values seem to suggest episodic fluid injections from the overpressured systems into the reservoirs.

Effect of Nitrogen On the Solubility And Diffusivity of Carbon Dioxide Into Oil And Oil Recovery By the Immiscible WAG Process T.A. Nguyen; T.A. Nguyen Petroleum Recovery Institute Search for other works by this author on: This Site Google Scholar S.M. Farouq Ali S.M. Farouq Ali Petroleum Recovery Institute Search for other works by this author on: This Site Google Scholar Paper presented at the Annual Technical Meeting, Calgary, Alberta, June 1995. Paper Number: PETSOC-95-64 https://doi.org/10.2118/95-64 Published: June 06 1995 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Get Permissions Search Site Citation Nguyen, T.A., and S.M. Farouq Ali. "Effect of Nitrogen On the Solubility And Diffusivity of Carbon Dioxide Into Oil And Oil Recovery By the Immiscible WAG Process." Paper presented at the Annual Technical Meeting, Calgary, Alberta, June 1995. doi: https://doi.org/10.2118/95-64 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsPetroleum Society of CanadaPETSOC Annual Technical Meeting Search Advanced Search AbstractIn the immiscible displacement of oil by carbon dioxide gas, the solution and diffusion of carbon dioxide are important factors that determine the efficiency of the process, since an increase in the carbon dioxide solubility and diffusivity into oil leads to an increase in oil recovery because the oil phase left behind contains more carbon dioxide and less oil. It is shown by experimental studies that the solubility and diffusivity of carbon dioxide into oil are governed by the saturation pressure, reservoir temperature I composition of the oil and purity of the gas. The solubility and diffusivity of carbon dioxide into Aberfeldy heavy oil were measured, using impure carbon dioxide gas containing nitrogen as the main ontaminant gas. It was noted that increasing the concentration of nitrogen in the carbon dioxide stream ecreased the solubility and. diffusivity of carbon dioxide into oil, consequently leading to a reduction in the swelling oil of by carbon dioxide.Displacement experiments were also conducted to observe the effect of using impure carbon dioxide in place of pure carbon dioxide in the immiscible displacement WAG process. It was noted that the presence of nitrogen in carbon dioxide adversely affected oil recovery by the process and that increasing the nitrogen concentration up to 30 mole% could result in 10% loss in oil recovery.IntroductionThe solubility of carbon dioxide is the most important effect in the immiscible displacement of oil by carbon dioxide gas since it is theorized that among other mechanisms, an increase in the carbon dioxide solubility in oil leads to an increase in oil recovery because the oil phase left behind contains more carbon dioxide and less oil.Early work in 1926 by Beecher and Parkhurst1 showed that carbon dioxide was more soluble on a molar basis in a 30.2 °API oil than air and natural gas. Svreck and Mehrotra's data2 also showed that, among the three gases: carbon dioxide methane, and nitrogen, carbon dioxide is the most soluble and nitrogen the least soluble in bitumen.The solubility of carbon dioxide in oil is governed by the saturation pressure, reservoir temperature, composition of the oil and purity of the gas. Miller and Jones3 and Chung, Jones, and Nguyen4 measured the solubility of carbon dioxide n Canyon and Wilmington heavy oils and found that the solubility of carbon dioxide in heavy crude oils increased with pressure but decreased with temperature and reduced API gravity. Later, Sayegh and Sarbar5 established that carbon dioxide is more soluble in oil at lower temperatures than at higher ones. Patton, Coats, and Spence6, Holm and Josendal7, and Chung et al4 showed that the solubility of carbon dioxide reduced with me presence of methane in oil since carbon dioxide had to displace methane before dissolving in oil Holm and Josendal7 also mentioned that carbon dioxide did not displace all of the methane when it came into contact with oil. Spivak and Chima noted that the solubility of pure carbon dioxide in oil was higher than that of a carbon dioxide-nitrogen mixture. Keywords: upstream oil & gas, dioxide, petroleum society, experiment, oil recovery, pvt measurement, carbon dioxide, carbon dioxide solubility, nitrogen, carbon dioride Subjects: Fluid Characterization, Improved and Enhanced Recovery, Phase behavior and PVT measurements This content is only available via PDF. 1995. Petroleum Society of Canada You can access this article if you purchase or spend a download.

Reinforced concrete is widely used in the construction of buildings, historical monuments and also nuclear power plants. For various reasons, many concrete structures are subject to unavoidable cracks that accelerate the diffusion of atmospheric carbon dioxide to the steel/concrete interface. Carbonation at the interface induces steel corrosion that may cause the development of new cracks in the structure, and this is a determining factor for its durability. It is therefore important to accurately characterize the length of the load-induced damage along the steel/concrete interface in order to understand the effect of cracking on corrosion initiation and propagation. The aim of this paper is to present an experimental procedure that allows the load-induced damage length to be assessed. The procedure consists in subjecting specimens to accelerated carbonation and determining the length of the carbonated steel/mortar interface, which is assumed to be equal to the length of the damaged steel/mortar interface. Suitable conditions should therefore be found for the accelerated carbonation in order to obtain an accurate characterization of the damaged steel/mortar interface length. To this end, two carbonation concentrations (3, 50%) and several carbonation durations were tested. The results indicate that a strong carbonation shrinkage phenomenon develops at high carbon dioxide concentration and leads to new cracking along the steel/mortar interface. These cracks allow the carbon dioxide to spread along the interface over a length greater than the damaged length. This is not the case when the accelerated carbonation test is performed at lower carbon dioxide concentration. Consequently, accelerated carbonation at high carbon dioxide concentration (50%) cannot be used neither for the estimation of the length of the mechanically damaged steel/mortar interface nor for the carbonation-induced corrosion studies because it will lead to an overestimation of the size of the corroded area.

ASSIMILATION AND RESPIRATION OF EXCISED LEAVES AT HIGH CONCENTRATIONS OF CARBON DIOXIDE

The standard industrial process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines, but the lack of reliable and accurate vapor–liquid equilibrium (VLB) data impedes the commercial application of more efficient alkanolamine systems. A novel Fourier‐transform infrared (FTIR) technique was developed to make in‐situ VLE measurements of acid‐gas‐aqueous alkanolamine systems and to improve the accuracy of VLE measurements at low hydrogen sulfide and carbon dioxide concentrations. VLE measurements of low carbon dioxide and hydrogen sulfide concentrations in aqueous mixtures of methyldiethanolamine (MDEA) are reported using the new FTIR technique.

The effect of pressure on diffusivity in binary or multicomponent systems such as gas−liquid or gas−solid systems has rarely been reported. The diffusivity of carbon dioxide in extruded gelatinized starch has been measured in this study at pressures of up to 117 bar (1700 psi). Such data are fundamentally not only useful in the understanding of the supercritical carbon dioxide (SC-CO2)/starch systems but also can be useful for the design and control of processes utilizing carbon dioxide injection or mixing in starch-based matrices. The methodology developed here was an improvement over a previously reported technique, enabling high-pressure data to be obtained. The diffusivity of carbon dioxide in the melt was found to be a strong function of pressure but not of moisture content in the range of 34.5−39% (w/w) studied. This diffusivity value decreased from 7.5 × 10-10 to 0.9 × 10-10 m2/s as pressure was increased from atmospheric to 115 bar. The low-pressure diffusivity value was only an order of magnitude lower than that reported for a carbon dioxide in water system and comparable to reported values of diffusivity of CO2 in softened polymers. These diffusivity values are also the same order of magnitude as the reported values of the diffusivity of water in starch, suggesting similar mechanisms of diffusion for carbon dioxide and water diffusivity in starch. The observed pressure dependency of the diffusivity may be due to the melt's high compressibility at these pressures. The solubility of carbon dioxide in the starch melt was proportional to the product of the solubility of carbon dioxide in water and the melt's moisture content.

There was an increase in total petroleum hydrocarbons (TPH) concentrations at all three depths within Borehole DRA-0. The oxygen concentration at 40 ft below ground surface (bgs) decreased. There was also an increase in carbon dioxide concentration at that depth. The decrease in oxygen concentrations and the increase in carbon dioxide concentration at the 40 ft bgs level could be possible indicators of natural attenuation. It is not possible to determine trends or biodegradation rates with the limited amount of data collected from the site. The sample results from this first monitoring period did not correlate with the baseline results collected in August 2000. Additional samples will be collected and the results will be compared to previously collected samples to determine if the site was at equilibrium in August 2000. Continued annual monitoring will be conducted as specified in the Closure Report to determine trends at the site. As natural attenuation occurs, the TPH concentrations should decrease. The TPH concentrations will be compared over successive monitoring events to determine trends and approximate rates. As natural attenuation occurs, oxygen will be consumed and carbon dioxide will be produced. The oxygen, nitrogen, and carbon dioxide concentrations will also be evaluated to determine if biodegradation is indicated. When all available oxygen has been consumed, methane-producing bacteria may continue the natural attenuation process so methane levels will be monitored as an additional possible indicator of natural attenuation. The rate of decrease will be determined on the microbial populations, contaminant concentrations, available nutrients, and other environmental factors. Samples were collected and submitted for microbial analysis during closure activities. The results indicated that the microbial populations and nutrients were adequate for limited bioremediation (DOE/NV, 2000). Additional sampling for microbial analysis are not planned. The site is currently inactive and the source of additional contamination was removed. It was determined during closure activities that the wetting front has stabilized. Monitoring of Borehole DRA-3 has not shown any indications of contamination. Contamination migration to the water table is not expected based on current site conditions.