Critical Temperatures and Critical Pressures of Hydrocarbon Mixtures. Methane Ethane-n-Butane System.

1962 ◽  
Vol 7 (1) ◽  
pp. 62-65 ◽  
Author(s):  
H. M. Cota ◽  
George Thodos
Keyword(s):  
Critical Temperatures ◽  
Hydrocarbon Mixtures

The Cricondentherm and Cricondenbar Pressures of Multicomponent Hydrocarbon Mixtures

1964 ◽  
Vol 4 (03) ◽  
pp. 240-246 ◽  
Author(s):  
Robert B. Grieves ◽  
George Thodos
Keyword(s):  
Boiling Point ◽  
Binary Data ◽  
Binary Systems ◽  
Calculation Procedure ◽  
Hydrocarbon Mixture ◽  
Multicomponent Mixtures ◽  
Critical Temperatures ◽  
Average Deviation ◽  
Hydrocarbon Mixtures ◽  
Industrial Processing

Abstract A method is presented for the accurate calculation of the cricondentherm and cricondenbar pressures of multicomponent hydrocarbon mixtures of known composition. The mixtures may contain six and quite possibly any number of components including paraffins, isoparaffins, olefins, acetylenes, naphthenes and aromatics. The approach is similar to that used for calculating critical pressures and cricondentherm and cricondenbar temperatures. The critical pressure, the normal boiling point and the approximate vapor pressure behavior of each component are all that are required. A stepwise calculation procedure is necessary for mixtures containing more than two components. From an analysis of 22 binary systems and 118 mixtures, the average deviation of calculated cricondentherm pressures from reported values is 2.4 per cent. For nine multicomponent mixtures the average deviation is 1 per cent. Considering 19 binary systems and 108 mixtures, the average deviation of calculated cricondenbar pressures from reported values is 1.7 per cent. For 15 multicomponent mixtures, the average deviation is 2.2 per cent. Introduction A knowledge of the phase behavior in the critical region of multicomponent hydrocarbon mixtures is of value both in industrial processing operations and for the optimum operations of gas condensate reservoirs. Accurate methods of calculating the critical temperatures and critical pressures and cricondentherm and cricondenbar temperatures of multicomponent hydrocarbon mixtures are available in the literature. If the cricondentherm and cricondenbar pressures could be calculated with equal accuracy, the entire phase diagram of a multicomponent hydrocarbon mixture could be well approximated. The work of Etter and Kay is limited to systems containing the normal paraffins and has not been tested on systems containing a heavier component than heptane. In addition, the development of their multicomponent equations is based upon a limited number of mixtures containing from three to six components. Silverman and Thodos have considered systems containing both paraffinic and non-paraffinic hydrocarbons, but their correlation is limited to binary systems and is highly inaccurate for methane systems. Eilerts has done extensive work on the cricondenbar pressure; he has produced an excellent correlation for binary systems. However, his procedure for multicomponent mixtures is chiefly useful for highly complex mixtures requiring a knowledge of the vapor-liquid equilibrium behavior of the mixtures; he has not considered the cricondentherm pressure. The objective of this study was the development of an accurate and rapid method for the calculation of the cricondentherm and cricondenbar pressures of multicomponent mixtures containing all types of hydrocarbons and having a wide volatility range. The approach that was adopted is similar to that used by Grieves and Thodos for cricondentherm and cricondenbar temperatures and for critical pressures. However, methane systems had to be considered separately and a modified stepwise calculation procedure was utilized for the cricondentherm pressure. The correlations were developed in a manner similar to those for critical pressures and cricondentherm and cricondenbar temperatures. Based upon binary data reported in the literature it was observed that the ratios of cricondentherm and cricondenbar pressure to the pseudocritical pressure (molar average), pt/ppc and pp/ppc respectively, in two-component systems depended upon the mole fraction of this low-boiling component and upon the diversity in properties of the two components. A dimensionless boiling-point parameter T'b/Tb was chosen to represent the diversity in properties of the components. For a binary system, T't, is the molar average of the normal boiling points of the two components involved. SPEJ P. 240ˆ

Phase-Behavior of Carbon-Dioxide and Hydrocarbon Mixtures

1985 ◽  
Vol 38 (12) ◽  
pp. 1739 ◽  
Author(s):  
RJ Sadus ◽  
CL Young
Keyword(s):  
Carbon Dioxide ◽  
Phase Behavior ◽  
Equations Of State ◽  
Fluid Model ◽  
Van Der Waals ◽  
Solubility Data ◽  
Critical Temperatures ◽  
Hydrocarbon Mixtures ◽  
Critical Solution Temperatures

Upper critical solution temperatures, gas-liquid critical temperatures and solubility data of carbon dioxide and hydrocarbon mixtures have been used to obtain a parameter, ξ, characterizing the interaction between pairs of unlike molecules in the mixture. The calculation of ξ values involved the use of the van der Waals one-fluid model together with the Guggenhiem and Redlich-Kwong equations of state. There is a discrepancy of several percent between ξ values calculated from the three sources of data. Trends in the value of ξ are discussed briefly.

Rapid Critical Point Drying of Tissues in a Parr Bomb

1972 ◽  
Vol 30 ◽  
pp. 400-401
Author(s):  
C.A. Baechler ◽  
W. C. Pitchford ◽  
J. M. Riddle ◽  
C.B. Boyd ◽  
H. Kanagawa ◽  
...  
Keyword(s):  
Critical Point ◽  
Critical Pressure ◽  
Soft Tissues ◽  
Biological Tissues ◽  
Critical Temperatures ◽  
Air Drying ◽  
The Past ◽  
Critical Point Drying ◽  
Great Stress ◽  
Infiltration Techniques

Preservation of the topographic ultrastructure of soft biological tissues for examination by scanning electron microscopy has been accomplished in the past by using lengthy epoxy infiltration techniques, or dehydration in ethanol or acetone followed by air drying. Since the former technique requires several days of preparation and the latter technique subjects the tissues to great stress during the phase change encountered during air-drying, an alternate rapid, economical, and reliable method of surface structure preservation was developed. Turnbill and Philpott had used a fluorocarbon for the critical point drying of soft tissues and indicated the advantages of working with fluids having both moderately low critical pressures as well as low critical temperatures. Freon-116 (duPont) which has a critical temperature of 19. 7 C and a critical pressure of 432 psi was used in this study.

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