Water and hydrocarbons

An easy to use nomograph has been developed for the solubility of liquid hydrocarbons in water at ambient conditions (25°C). The accuracy of the nomograph has been checked against available solubility data. Performance of the nomograph has been compared with the predictions given by two available analytical correlations. The nomograph is much simpler to use and far more accurate than either of the analytical methods. 

Development of the Nomograph. Two main sources of data were used to develop the nomograph McAuliffe and Price. The hydrocarbons were divided into 14 homologous series as listed in Table 1. Solubilities at 25°C were then regressed with the carbon numbers of the hydrocarbons in order to obtain the best fit for each homologous series. A second order polynomial equation fits the data very well  

S = the solubility in mole fraction a,b = regression constants C = the carbon number of the hydrocarbon 

Regression Constants and Nomograph Coordinates for the Solubilities of Liquid Hydrocarbons in Water at 25 C 

Homologous Series No. of Compounds Regression Constants a b Nomograph Coordinates X Y  

Aromatics-single ring, mono and disubstituted by n-paraffins 6 1.91 0.0418 23.5 66.1 

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An adequate prediction of multicomponent vapor-liquid equilibria requires an accurate description of the phase equilibria for the binary systems. We have reduced a large body of binary data including a variety of systems containing, for example, alcohols, ethers, ketones, organic acids, water, and hydrocarbons with the UNIQUAC equation. Experience has shown it to do as well as any of the other common models. V7hen all types of mixtures are considered, including partially miscible systems, the... 

When a customer agrees to purchase gas, product quality is specified in terms of the calorific value of the gas, measured by the Wobbe index (calorific value divided by density), the hydrocarbon dew point and the water dew point, and the fraction of other gases such as Nj, COj, HjS. The Wobbe index specification ensures that the gas the customer receives has a predictable calorific value and hence predictable burning characteristics. If the gas becomes lean, less energy is released, and if the gas becomes too rich there is a risk that the gas burners flame out . Water and hydrocarbon dew points (the pressure and temperature at which liquids start to drop out of the gas) are specified to ensure that over the range of temperature and pressure at which the gas is handled by the customer, no liquids will drop out (these could cause possible corrosion and/or hydrate formation). 

Gas Water and hydrocarbon dew point, hydrocarbon composition, contaminants content, heating value. 

Monobutylamines are easily soluble in water and hydrocarbons and can generally be steam distilled. These properties lead to uses in soaps for water and oil emulsions, and as corrosion inhibitors in steam boiler appHcations (see Corrosion and corrosion inhibitors Emulsions). Morpholine is also extensively used as a corrosion inhibitor in steam boiler systems. In addition, it is widely used as an intermediate in the production of delayed-action mbber accelerators. 

Fig. 11. In a system of water and hydrocarbon a nonionic emulsifier with a poly(ethylene glycol) chain as the polar part dissolves in the aqueous phase at low temperatures (a) and in the oil phase at high temperatures (c). At an intermediate temperature (b) three isotropic Hquid phases may be found.

Onshore or offshore gas plants are designed for either LNG rejection and gas injection, or LNG rejection and transmission for sale. In the case of offshore plants, onshore facilities further process the natural gas before transmission for sale. In either case, natural gas must be treated and then refrigerated to make rejection of heavy hydrocarbons possible. In plants where natural gas is treated for sale purposes, water and hydrocarbon dew points of the gas must also be controlled. 

Liquids Free of liquid water and hydrocarbons at delivery temperature and pressure. ... 

To meet sales specifications, gas produced at the wellheads must be free of water and hydrocarbon liquids. Twin turboexpanders are a key component in this process, providing dewpoint control with optimal efficiency. Initial processing takes place at the wellhead platforms, where methanol is injected to inhibit hydrate formation. A corrosion inhibitor is also added to prevent gas from damaging downstream equipment. 

At the central platform, water and hydrocarbon liquids are first removed in knockout drums. Then saturated natural gas, free of any liquid droplets, enters the twin expanders. The gas is cooled below its dewpoint, allowing heavy hydrocarbon components and water vapor to condense in the discharge stream. Turboexpanders were chosen for two main reasons They are more compact than competing methods of controlling the dewpoint and their operating costs are typically lower than those of many alternatives. 

Blowdown systems utilize a series of flash drums and condensers to separate the blowdown into its vapor and liquid components. The liquid is typically composed of mixtures of water and hydrocarbons containing sulfides, ammonia, and other contaminants, which are sent to the wastewater treatment plant. 

Commonly, amine absorbers include an integral gas. scrubber section in the bottom of the tower. This scrubber would be the same diameter as required for the tower. The gas entering the tower would have to pass through a mist eliminator and then a chimney tray. The purpose of this scrubber is to remove entrained water and hydrocarbon liquids from the gas to protect the amine solution from contamination. 

The temperature of the regeneration gas that commingles with the incoming wet gas ahead of the dehydrators is also important. If the tem perature of these two gas streams differs more than 15°F to 20°F, liquid water and hydrocarbons will condense as the hotter gas stream cools. I hc condensed liquids can shorten the solid desiccant life. 

The temperature of the regeneration gas in the regeneration gas scrubber should be low enough to condense and remove the water and hydrocarbons from the regeneration gas without causing hydrate problems. 

Bromine trifluoride, though it reacts explosively with water and hydrocarbon tap greases, is somewhat less violent and vigorous a fluorinat-ing agent than is CIF3. The sequence of reactivity usually quoted for the halogen fluorides is ... 

Nonmetals form covalent molecular hydrides, which consist of discrete molecules. These compounds are volatile and many are Bronstcd acids. Some are gases— for example, ammonia, the hydrogen halides (HF, HC1, HBr, HI), and the lighter hydrocarbons such as methane, ethane, ethene, and ethyne. Liquid molecular hydrides include water and hydrocarbons such as octane and benzene. 

J. Dahl, K. Harris, and K. McKown. Uses of small particle size cement in water and hydrocarbon based slurries. In Proceedings Volume, pages 25-29.9th Kansas Univ et al Tertiary Oil Recovery Conf (Wichita, KS, 3/6-3Z7), 1991. 

The next development on water-oil isotherms was presented by Mohwald s group at the Max-Planck Institute in Berlin [21,22]. They investigated monolayers of dipalmitoyl phosphatidylethanolamine (DPPE) at interfaces of water and hydrocarbons -dodecane (C]2, -hexadecane (Cig), and bicyclohexyl (BCH). The transition pressure was increased and the molecular area at transition decreased in the order Cig—C12 BCH. Also the heat of transition was decreased in the same order, and was more strongly decreasing with... 

The response from the water and hydrocarbon can be distinguished by measuring the distributions of the diffusion coefficients simultaneously with the distributions of the relaxation times. The resulting distributions are displayed on a two-dimensional diffusion coefficient-relaxation time map and the distributions for... 

Subczynski, W. K. and J. S. Hyde. 1984. Diffusion of oxygen in water and hydrocarbons using an electron spin resonance spin-label technique. Biophys. J. 45 743-748. 

The decomposition of hydroperoxides occurs preferentially in the surface layer of water and hydrocarbon. The larger the surface per unit volume of hydrocarbon the faster the decomposition of hydroperoxide. Therefore, the increase in an aqueous phase accelerates hydrocarbon oxidation. The optimal RH H20 ratio was found to be nearly 1 1 (v/v) [19], if the calculation of the reaction rate per unit volume of the whole mixture is done. The introduction of surfactants that creates the smaller drops of hydrocarbons increases the surface and, therefore, accelerates the oxidation. 

A detailed justification of the surfactant parameter approach is still the subject of theoretical investigations, and we will return to several issues below. We mention that the surfactant parameter approach is consistent with the fluid mosaic model of Singer and Nicolson. It tells us that the self-assembly of amphiphiles is driven by the strong segregation of water and hydrocarbon chains, and that packing effects dominate the self-assembly process. 

The set of parameters, i.e. the force-field parameters used in the SCF calculations, are listed in Table 1. We will not discuss all of them. The most important one is the repulsion between water and hydrocarbon. The value of this FH parameter is set to Xh2o, c = 0-8. One should remember however that in... 

Hydrogen occurs naturally in the form of chemical compounds, most frequently in water and hydrocarbons. Hydrogen can be produced from fossil fuels, nuclear and renewable energy sources by a number of processes, such as natural gas reforming,... 

Water and hydrocarbons occurring together, in shallow aquifer systems, may be considered immiscible for flow calculation purposes however, each is somewhat soluble in the other. Since groundwater cleanup is the purpose behind restorations, it receives greater attention. Definition of water quality based on samples retrieved from monitoring wells relies heavily upon the concentration of individual chemical components found dissolved in those samples. An understanding of the processes that cause concentration gradients is important for the proper interpretation of analytical results. 

For example, the behaviour with water and hydrocarbons depends on the grade, stabilization, immersion time and the actual temperature. According to the sources and conditions, assessments vary from satisfactory to unsatisfactory. 

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