Minimum miscibility pressure

The latter quantity is usually determined phenomenologically by measuring displacements of crude oil with carbon dioxide (or other injection fluid) from a long capillary tube (i.e., "slim tube") at a series of successively higher pressures. A plot of displaced oil versus pressure usually has a break at about 95-percent recovery, which is taken as the "minimum miscibility pressure." Often this is not a true miscibility in the correct thermodynamic sense. For example, many crudes contain asphaltenes that precipitate and do not dissolve even after a series of theoretical "multiple contacts" between the crude and the propagating mixture of injection fluid and non-asphaltenic components of the crude. 

The enrichment (or the pressure) needed to develop miscibility between the injectant and the oil is determined experimentally in one-dimensional slim-tube tests.As the enrichment (or pressure) increases, the slim-tube recovery reaches a plateau long before first contact miscibility is developed. This enrichment is called the minimum miscibility enrichment, or MME, which is a function of reservoir pressure, temperature, and contaminants in the solvent. Similarly, a pressure called the minimum miscibility pressure, or MMP, can be identified for any solvent. Other experimental methods (e.g., rising bubble method) are also available to determine MMP or MME. In vaporizing three component systems, MMP (or MME) corresponds to the pressure (or enrichment) at which the critical tie line passes through the crude oil composition. In condensing three component systems, MMP (or MME) corresponds to the pressure (or enrichment) at which the critical tie line passes through the solvent composition. ... 

Wang, Y. Orr, F.M., Jr. Analytical calculation of minimum miscibility pressure. Fluid Phase Equilibria 1997, 139, 101-124. 

Nasrifar, Kh. and Moshfeghian, M. (2004). Application of an Improved Equation of State to Reservoir Fluids Computation of Minimum Miscibility Pressure. J. Petro. Sci. Eng. 42, 223. 

Vahidi, A. and Zargar, Gh. (2007) Sensitivity analysis of important parameters affecting minimum miscibility pressure (MMP) of nitrogen injection into conventional oil reservoirs. SPE/EAGE Reservoir Characterization and Simulation Conference 2007, Society of Petroleum Engineers, pp. 247-257. 

Evaporation into Vacuous Space.—When two volatile liquids—miscible, partially miscible or non-miscible—are placed together in a vacuous space, such as that over the mercury in a barometer tube, evaporation takes place, and, as a rule, the composition of the residual liquid differs from that of the vapour. It is only when the liquids form a mixture of maximum or minimum vapour pressure—and therefore of constant boiling point—and when it is this particular mixture that is introduced into the vacuous space, that the composition of the vapour is the same as that of the liquid. In all other cases the vapour is richer in the more volatile of the two components into which the mixture tends to separate when distilled, these components being either the original substances from which the mixture was formed, or one of these substances and a mixture of the two which has a higher or lower boiling point than that of either of the original constituents. 

FURFURALDEHYDE. [CAS 98-01-1]. 2-C4H-,0 CHO. formula weight 192.16. colorless, odorous (pungent, almond-like) liquid aldehyde, mp —38.7°C. bp I61.7CC. sp gr 1.159. Also known as 2-luraldehyde or 2-furancarboxalde hyde, this compound becomes brown in color when in contact with air. Furfural is modestly soluble in 114) (up to 8% by weight at 20cC) and is miscible in all proportions with alcohol and ether. At atmospheric pressure, a mixture of furfural and H 0 (65%) forms a minimum-boiling azeotrope when a distillation temperature of 97.9°C is reached. 

At atmospheric pressure, the n-butanol-water system exhibits a minimum boiling azeotrope and partial miscibility, and hence a binary heterogeneous azeotrope. Figure 1.8 shows the Tyx and Pyx phase diagrams for l-propanol(l)-water(2) azeotropic mixture obtained from the Aspen Plus simulator using the NRTL activity coefficient model. 

Some of the solubility data given in this patent have already been discussed in Chapter 10. Friedrich has found that at conditions above 60 °C and 550 atm the solubility of triglycerides in CO2 rises dramatically. He shows that soy bean triglycerides become infinitely miscible above about 800 atm and 70 °C. Based upon these findings he proposes a process for extracting soy beans, cotton seed, and similar oil seeds, using CO2 at very high pressure with a minimum recycle. For example, solubility levels of 20 to 40% are reported at conditions of 6(X) atm and 70 °C. 

O homogeneous azeotrope in a completely miscible system L homogeneous azeotrope in a partially miscible system E heterogeneous azeotrope X pressure maximum N pressure minimum D double azeotrope... 

Figure 1 Different types of binary azeotropic systems I - homogeneous pressure-maximum azeotrope in a completely miscible system (OX) II - heterogeneous pressure-maximum azeotrope (EX) III - homogeneous pressure-minimum azeotrope in a completely miscible system (ON) IV - homogeneous pressure-maximum azeotrope in a partially miscible system (LX) V - D double azeotrope (OND, OXD) VI - homogeneous pressure-minimum azeotrope in a partially miscible system (LN). A -yi( i) B - P(xj) and P(ji) C - T x ) and T(yj). Continuous line - ( j) Dashed line - (yj).

Even though K depends only on temperature and pressure, it has an upper limit imposed by chemical stability that varies with composition. The minimum upper limit of K occms for an eqnimolar mixture where yi = y2 =. Hence, complete miscibility in regular solutions is consistent with K <2 (see Tester and Modell, 1997, p. 359). 

For still lower mutual miscibility of the components critical p(X) curves without any pressure maximum or minimum may be obtained, as indicated in Figure 26d by a dotted line. Such a phase behaviour is attributed to gas-gas equilibria (GG) (see Figure 18) and may be found in mixtures of COg with alkanes having more than 30 carbon atoms it has already been found for the COg + water system (see Figure 21). 

In Figure 30 the phase behaviour of the systems in Figure 28 is deduced from a superposition of liquid-liquid and gas-liquid equilibria. - Figures 30a and 30c correspond to a binary system with a gas-liquid critical curve LG showing a temperature minimum and with a phase separation into two liquid phases at lower temperatures, the UCST rising with increasing pressure. This type has been found for the naphthalene + H2O and biphenyl + H20 systems. They are the first hydrocarbon + H2O systems where complete miscibility in all proportions has been found in ranges of temperature and pressure which... 

For our second nonideal system, we look at a process that has extremely nonideal VLB behavior and has a complex flowsheet. The components involved are ethanol, water, and benzene. Ethanol and water at atmospheric pressure form a minimum-boiling homogeneous azeotrope at 351K of composition 90mol% ethanol. Much more complexity is introduced by the benzene/water system, which forms two liquid phases with partial miscibility. The flowsheet contains two distillation columns and a decanter. There are two recycle streams, which create very difficult convergence problems as we will see. So this complex example is a challenging simulation case. 

The location of the azeotropic point depends on pressure, its position in the equilibrium diagram shifts to the right with a decrease in pressure. A higher fraction of more volatile component is then found in the azeotropic mixture. The separation of such a liquid mixture by distillation is based on this fact. Components are completely miscible and form a minimum or maximum azeotrope without a third component. 

Wilder Dwight Bancroft (Middletown, Rhode Island, U.S.A., i October 1867-New York, 7 February 1953) was professor of physical chemistry in Cornell University, Ithaca, New York, and editor of the Journal of Physical Chemistry, He also published on the phase rule (see p. 638), colloid chemistry (see p. 739), and structure colours. He showed that two immiscible liquids become miscible if a third substance, soluble in each, is added investigated ternary mixtures, equilibrium in 2-component systems, analysis of solid phases, suggested that all miscible liquids whose vapour pressure curves cut one another form mixtures of maximum or minimum boiling-point, and stated the equations for electromotive forces in terms of chemical potentials. ... 

C, the miscibility gap has vanished (see Figure F.l). Instead, large negative deviations from Raoult s law and a pressure-minimum azeotrope are observed. This can hardly be believed. A negative deviation from Raoult s law means that the 1,1,2-trichloroethane will leave the stripper at the bottom of the column, this means the stripper will not work. Together with the suspicion that the parameters are strange, a revision of the model should take place. 

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