Petroleum hydrocarbons physical properties

These experts collectively have knowledge of total petroleum hydrocarbons physical and chemical properties, toxicokinetics, key health end points, mechanisms of action, human and animal exposure, and quantification of risk to humans. All reviewers were selected in conformity with the conditions for peer review specified in Section 104(i)(13) of the Comprehensive Environmental Response, Compensation, and Liability Act, as amended. 

Knowledge of physical properties of fluids is essential to the process engineer because it enables him to specify, size or verify the operation of equipment in a production unit. The objective of this chapter is to present a collection of methods used in the calculation of physical properties of mixtures encountered in the petroleum industry, different kinds of hydrocarbon components, and some pure compounds. 

Physical Properties. Benzene, C H, toluene, C Hj-CH, and petrol (a mixture of aliphatic hydrocarbons, e.g., pentane, hexane, etc.) are colourless liquids, insoluble in and lighter than water. Benzene and toluene, which have similar odours, are not readily distinguishable chemically, and their physical constants should therefore be carefully noted benzene, m.p. 5 (solidifies when a few ml. in a dry test-tube are chilled in ice-water), b.p. 8i toluene, m.p. —93°, b.p. 110°. Petroleum has a characteristic odour. 

The feedstocks used ia the production of petroleum resias are obtaiaed mainly from the low pressure vapor-phase cracking (steam cracking) and subsequent fractionation of petroleum distillates ranging from light naphthas to gas oil fractions, which typically boil ia the 20—450°C range (16). Obtaiaed from this process are feedstreams composed of atiphatic, aromatic, and cycloatiphatic olefins and diolefins, which are subsequently polymerized to yield resias of various compositioas and physical properties. Typically, feedstocks are divided iato atiphatic, cycloatiphatic, and aromatic streams. Table 2 illustrates the predominant olefinic hydrocarbons obtained from steam cracking processes for petroleum resia synthesis (18). 

Hydrocarbons are segmented into a variety of categories. Each category possesses a distinct molecular profile and, in turn, set of chemical and physical properties. Each class of hydrocarbons therefore has historically served different markets. Crude petroleum is composed of four major hydrocarbon groups paraffins, olefins, naphthenes, and aromatics. 

Mineral Oil Hydraulic Fluids and Polyalphaolefin Hydraulic Fluids. Limited information about environmentally important physical and chemical properties is available for the mineral oil and water-in-oil emulsion hydraulic fluid products and components is presented in Tables 3-4, 3-5, and 3-7. Much of the available trade literature emphasizes properties desirable for the commercial end uses of the products as hydraulic fluids rather than the physical constants most useful in fate and transport analysis. Since the products are typically mixtures, the chief value of the trade literature is to identify specific chemical components, generally various petroleum hydrocarbons. Additional information on the properties of the various mineral oil formulations would make it easier to distinguish the toxicity and environmental effects and to trace the site contaminant s fate based on levels of distinguishing components. Improved information is especially needed on additives, some of which may be of more environmental and public health concern than the hydrocarbons that comprise the bulk of the mineral oil hydraulic fluids by weight. For the polyalphaolefin hydraulic fluids, basic physical and chemical properties related to assessing environmental fate and exposure risks are essentially unknown. Additional information for these types of hydraulic fluids is clearly needed. 

Camin, D.L., Rossini, F. (1955) Physical properties of 14 American Petroleum Institute research hydrocarbons, C9 to C15. J. Phys. Chem. 59, 1173-1179. 

Naphthenes or cycloparaffins are formed by joining the carbon atoms in ring-type structures, the most common molecular structures in petroleum. These hydrocarbons are also referred to as saturated hydrocarbons since all the available carbon atoms are saturated with hydrogen. Typical naphthenes and their respective physical properties are listed in Table 4.2 and shown in Figure 4.3. 

Nyer, E. K. and Skladany, G. J., 1989, Relating the Physical and Chemical Properties of Petroleum Hydrocarbons to Soil and Aquifer Remediation Ground Water Monitoring Review, Winter, pp. 54—60. 

Petroleum is typically described in terms of its physical properties (such as density and pour point) and chemical composition (such as percent composition of various petroleum hydrocarbons, asphaltenes, and sulfur). Although very complex in makeup, crude can be broken down into four basic classes of petroleum hydrocarbons. Each class is distinguished on the basis of molecular composition. In addition, properties important for characterizing the behavior of petroleum and petroleum products when spilled into waterways or onto land and/or released into the air include flash point, density (read specific gravity and/or API gravity), viscosity, emulsion formation in waterways, and adhesion to soil. 

Despite the large number of hydrocarbons found in petroleum products aud the widespread nature of petroleum use and contamination, many of the lower-boiUng constituents are well characterized in terms of physical properties, but only a relatively small number of the compounds are well characterized for toxicity. The health... 

Another approach is to consider petroleum constituents in terms of transportable materials, the character of which is determined by several chemical and physical properties (i.e., solubility, vapor pressure, and propensity to bind with soil and organic particles). These properties are the basis of measures of teachability and volatility of individual hydrocarbons. Thus, petroleum transport fractions can be considered by equivalent carbon number to be grouped into 13 different fractions. The analytical fractions are then set to match these transport... 

Changes in the chemical composition of the kerosene during volatilization also affect the physical properties of this petroleum product. Table 16.8 summarizes the effect of volatilization on kerosene viscosity, surface tension, and density when 20%, 40%, and 60% of the initial amount has been removed by the partial transfer of light hydrocarbon fractions to the atmosphere. Only the liquid viscosity is affected, with volatilization having a negligible effect on the density and surface tension of the kerosene. 

Heath JS, and Koblis K. 1993. Review of chemical physical and toxicological properties of components of total petroleum hydrocarbons. Journal of Soil Contamination 2(1) 125. 

Sachanen, A.N. Hydrocarbons in Petroleum, The Science of Petroleum, v.V, part I, Crude Oils Chemical and Physical Properties, B.T. Brooks and A.E. Dunstan (eds.), Oxford University Press, London (1950). 

Equation of state research has returned recently to the spirit of van der Waals, that is, cubic equations with two constants. Many equations of this form have been proposed.13 Two popularly accepted equations of state in the petroleum industry, Redlich-Kwong and Peng-Robinson, are cubic equations with two empirical constants. These equations have been used widely to calculate physical properties and vapor-liquid equilibria of hydrocarbon mixtures. 

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