Liquid Hydrocarbon Phase

This phase will be in dynamic equilibrium under the conditions of temperature, pressure, etc. with the vapor phase described above, as well as with the water phase contacting it. In this connection, it is of interest that the solubility of hydrogen sulfide and carbon dioxide in hydrocarbons is generally large compared to that of oxygen and nitrogen. 

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Methanol eoncentration has essentially no effect on predicted water content of the liquid-hydrocarbon phase. The water eontent (not shown in the tables) was about 0.02 mol%. 

High Temperature Hydrogen Attack In A Liquid Hydrocarbon Phase. 8... 

HIGH TEMPERATURE HYDROGEN ATTACK IN A LIQUID HYDROCARBON PHASE... 

A species frequently maintains phase equilibrium while it is reacting in one phase. An example is hydrocracking of heavy hydrocarbons in petroleum refining, where H2 from the vapor dissolves into the liquid hydrocarbon phase, where it reacts with large hydrocarbons to crack them into smaller hydrocarbons that have sufficient vapor pressure to evaporate back into the vapor phase. As long as equilibrium of the species between phases is maintained, it is easy to calculate the concentrations in the hquid phase in which reaction occurs. 

Water droplets settle out of a lighter liquid hydrocarbon phase because of gravity. The water is denser than the liquid hydrocarbons. Liquid droplets settle out of a lighter gas phase because of gravity. What is the difference The difference is viscosity. We neglected the effect on the gas viscosity when calculating the K value in KO drums. Gas viscosities are almost always very low. 

The diagram schematic is the same for simple hydrate systems of si (CH4 + H2O) and sll (N2 + H2O) as well as those of fixed natural gas mixture compositions, without a liquid hydrocarbon phase. Systems containing a liquid hydrocarbon are similar in behavior to the C3H8 + H2O diagram, discussed in Section 4.1.2. 

Katz (1972) first noted that hydrates could form from heavy liquids such as crude oils that have dissolved gases suitable for hydrate formation. He suggested that the point of hydrate formation from water and a liquid hydrocarbon phase (no gas present) could be predicted using the vapor-hydrate distribution coefficient Kvsi of Equation 4.1 together with the more common vapor-liquid distribution coefficient Kyu (=yi/xa). In this case Equation 4.3 becomes ... 

Techniques for hydrate inhibition deal with the methanol concentration in the aqueous liquid in equilibrium with hydrate at a given temperature and pressure. The user also must determine the amount of methanol to be injected in the vapor. This problem was addressed first by Jacoby (1953) and then by Nielsen and Bucklin (1983), who presented a revised methanol injection calculation. The most recent data are by Ng and Chen (1995) for distribution of methanol in three phases (1) the vapor phase, (2) the aqueous phase, and (3) the liquid hydrocarbon phase. 

Hydrate inhibition occurs in the aqueous liquid, rather than in the vapor or hydrocarbon liquid phases. While a significant portion of the methanol partitions into the water phase, a significant amount of methanol either remains with the vapor or partitions into any liquid hydrocarbon phase. Although the methanol mole fraction in the vapor or liquid hydrocarbon may be low relative to the water phase, the large amounts (phase fractions) of vapor and liquid phases will cause a substantial amount of inhibitor loss. 

In antiagglomeration, since the prevention method relies on emulsified water/hydrates, a condensed hydrocarbon is required (Mehta et al., 2003). The solid phase loading cannot exceed 50 volume% of the liquid hydrocarbon phase to prevent high viscosity associated with compacted slurry flow. The emulsion is broken and water is removed onshore or at a platform. 

The vertical reactor vessel is free of internal equipment and operates in a three-phase mode. The solid additive particles are suspended in the primary liquid hydrocarbon phase through which the hydrogen and product gases flow rapidly... 

When the product gases exit from the TLX, they are still too hot for compression and must be cooled to essentially ambient temperatures. Part of the additional cooling is accomplished in some plants with a direct oil quench the hot oil can be used to generate steam. Typically, in the final stage of cooling, a tower equipped with water sprays and a trap provides intimate contact between the water and the gaseous streams. The resultant water and liquid hydrocarbon phase (of heavier hydrocarbons) from this tower are separated in settling drums. Valuable products in both the water and oil phases are recovered and processed. The... 

Rorschach, R. L., and Gardner, F. T., Ind. Eng. Chem., 41, 1380 (1949). The Distribution of Hydrogen Sulfide Between Aqueous and Liquid Hydrocarbon Phases. 

The solubility of water in the liquid hydrocarbon phase is given as X, the mole fraction of water in the water-saturated liquid hydrocarbon phase. With the hydrocarbon phase molar rate designated as L and the water phase as L", the overall mole fraction of water in the mixed liquid phase is calculated as... 

The presence of a second liquid (hydrocarbon) phase increases the — AG°d value by a few kJ/mol, with the increase being largest for cyclohexane (of the hydrocarbons investigated) and becoming smaller with increase in the chain length of the hydrocarbon. 

The interaction parameters in the presence of a second liquid (hydrocarbon) phase, (Sjj and 3, for mixed monolayer formation at the aqueous solution-hydrocarbon interface and for mixed micelle formation in the aqueous phase, respectively, can be evaluated (Rosen, 1986) by equations analogous to 11.1, 11.2 and 11.3, and 11.4, respectively. The necessary data are obtained from interfacial tension-concentration curves. 

Finally, VLLE calculations can sometimes be simplified in systems containing water and hydrocarbons. Because the solubility of hydrocarbons in water is very small, simplified calculations can be made by assuming a pure liquid water phase. Methods exist [4] to estimate the amount of water present in the vapor and dissolved in the liquid hydrocarbon phase. Such a simplification could not be performed if the amount of hydrocarbon in the water were important (for example, if wastewater contamination were a key design variable), but it is often adequate for calculations in petroleum refining. 

Such smoothing of the threshold between polarities within the interfacial discontinuity surface is possible when the polarity of the introduced third component is intermediate with respect to those of two other components, that make up the phases in contact. The smoothing is especially effective, when it is achieved via the adsorption of diphilic molecules containing segments with different polarities. These molecules are the organic surfactants that can smoothen the difference in polarity between water and any solid or liquid hydrocarbon phase ( further referred to as oil ). When the adsorption takes place, the polar heads of the surfactant molecules are oriented towards water, while the hydrocarbon chains face the oil phase (Fig. III-5). As... 

Cholesterol does not form micelles because it is not sufficiently amphiphilic (even though it does have an —OH group) and its flat, rigid, fused-ring structure gives a solid rather than a liquid hydrocarbon phase at physiological temperatures. Such fluidity is required for micelle formation. However, cholesterol can form mixed micelles with amphiphilic lipids, and it enters monolayers as well where it constitutes -25% of the mass of the lipid bilayer in the plasma membranes of mammalian cells. 

An analysis of liquid hydrocarbon phase from the Fischer Tropsch reactor and reformer is given in Table XI. As indicated, the Fischer Tropsch product is... 

Smaller reactors are used since the kinetics of the reactions is much higher. Larger interfacial areas occur between the liquid catalyst and liquid hydrocarbon phase in current HF-type reactors than in those using sulfuric acid as the catalyst (5). Transfer of the hydrocarbon reactants to the interfaces where the main reactions occur is thus more rapid. 

It is worth pointing out that despite the similar arrangement of the hydrophilic and hydrophobic segments of surfactant molecules at the water/hydrocarbon interface, there is a principal difference in the driving force of the adsorption from the aqueons phase and from the liquid hydrocarbon phase (Figure 2.6). 

Cooling and condensing the offgas from step 1 by indirect heat exchange with glycol and cold water to produce an aqueous phase that is fed to step I, a noncondensible phase that is vented or burned, and a liquid hydrocarbon phase that represents a marketable product... 

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