Characterization factor, petroleum

To extend the applicability of the characterization factor to the complex mixtures of hydrocarbons found in petroleum fractions, it was necessary to introduce the concept of a mean average boiling point temperature to a petroleum cut. This is calculated from the distillation curves, either ASTM or TBP. The volume average boiling point (VABP) is derived from the cut point temperatures for 10, 20, 50, 80 or 90% for the sample in question. In the above formula, VABP replaces the boiling point for the pure component. 

Three frequently specified properties are density—specific gravity—API gravity, characterization factor, and sulfur content (2,6,7). The API (American Petroleum Institute) gravity is a measure of density or specific gravity (sp gr) ... 

The viscosity-gravity constant and the Universal Oil Prodncts characterization factor have been used to some extent as a means of classifying crnde oils. Both parameters are generally employed to give an indication of the paraffinic character of the crude oil, and both have been nsed, if a snbtle differentiation can be made, as a means of petroleum characterization rather than for petrolenm classification. 

Maxwell and Bonner [Ind. Eng. Chem., 49, 1187 (1957)], which is given in great detail in the API Technical Data Book—Petroleum Refining (op. cit.) and in the ASTM D 2892 test method. It includes a correction for the nature of the sample (paraffin, olefin, naphthene, and aromatic content) in terms of the UOP characterization factor, UOP-K, as given by... 

After petroleum recovery and prior to the commencement of refining, there needs to be an estimate of the potential behavior of petroleum during refining operations. Briefly, three frequently specified properties that are used to evaluate petroleum are density (specific gravity, API gravity), characterization factor, and sulfur content (Matar, 1992 Speight, 1999 2000 2001). 

Other factors, such as the Watson characterization factor, are also used. A highly paraffinic crude oil can have a characterization factor as high as 13, whereas a highly naphthenic crude oil can be as low as 10.5, and the breakpoint between the two types of crude oil is approximately 12. Sulfur content, the carbon residue, and distillation data are also valuable in petroleum evaluation (Speight, 2001). 

To take care of peak loads in the winter, the local gas company wishes to supplement its limited supply of natural gas (CH4) by catalytically hydrogenating a heavy liquid petroleum oil that it can store in tanks. The supplier says that the oil has a U.O.P. Characterization Factor of 12.0 and an API gravity of 30°API. To minimize carbon deposition on the catalyst, twice the required amount of hydrogen is introduced with the oil. The reactants enter at 70 F and after heat exchange the products leave at 70 F. Calculate the following, per 1000 ft of CH4 at the standard conditions in the gas industry ... 

In this appendix we present the results of the work of Smith and Watson and associates who related petroleum properties to a factor known as the characterization factor (sometimes called the UOP characterization factor). It is defined as... 

Other averages for boiling points are used in evaluating K and the other physical properties in this Appendix. (Refer to Danbert or Maxwell S for details.) This factor has been related to many of the other simple tests and properties of petroleum fractions, such as viscosity, molecular weight, critical temperature, and percentage of hydrogen, so that it is quite easy to estimate the factor for any particular sample. Furthermore, tables of the UOP characterization factor are available for a wide variety of common types of petroleum fractions as shown in Table K.l for typical liquids. 

Another derived number, the UOP characterization factor, is also a widely used method for defining petroleum the Characterization Factor is derived from the formula ... 

Again, because of the use of average data and the output of a value that falls (in this case) within a narrow range, it is questionable whether or not this characterization factor offers realistic or reliable information. Determining whether or not a feedstock is paraffinic is one issue, but one must ask whether there is a real difference between feedstocks when the characterization factor is 12.4 or 12.5 or even between feedstocks having characterization factors of 12.4 and 13.0. As the complexity of feedstocks increases from petroleum to heavy oil and beyond to tar sand bitumen, especially with the considerable overlap of compound types, there must be serious questions about the reliability of the number derived by this method. 

Calculation of UOP Characterization Factor and Estimation of Molecular Weight of Petroleum Oils, Method 375, UOP Laboratory Test Methods for Petroleum and Its Products, UOP Inc., Des Plaines, IL, 1986. 

Tabue 4r2. Characterization Factors or a Fbw Htdbocabbons, Petroleums, and Ttpical Stocks. (Conf nu [Pg.85]

Fig. 5-9. Molecular weights, pseudo critical temperatures, Characterization Factors, and gravities of petroleum fractions. Courtesy of Hougen and Wotson, Chem. Process Principles, vol. 1, John Wiley Sons, Inc., New York.)...

Further, molecular simulation and computational chemistry have evolved, and are evolving, into important tools for developing better characterization techniques where it is not possible to measure all data. Even so, it is precisely the molecular complexity of petroleum fluids that seems to be an inhibiting factor in the use of these methods for developing better characterization methods. However, identification of important functional groups in petroleum fluids applying molecular simulation and/or computational chemistry for use with group contribution methods to predict thermo-physical properties may be an area for further research. 

Since 1968 ICERP Ploiesti has been developed hydrofining technologies and catalyst systems for treating various petroleum cuts including blends of distillates with cracked feedstocks. The commercial hydrofining units in domestic refineries as well as those licensed in different countries are characterized by high service factors. 

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