Crude oil blending

Kelly, J.D., Mann, J.L. (2003) Crude oil blend scheduling optimization an application... 

People usually want to know in advance which crude oils should be mixed and in which volumetric ratios, in order to achieve the desired value of viscosity. Thus the prediction of viscosity of crude oil blends becomes a mathematical issue rather than experimental. That is done with the help of mixing rules. A total of 26 mixing rules are reported in the literature (Centeno et al., 2011 and references cited therein), which can be classified according to the number and type of parameters involved for calculation of viscosity, as well as the experimental information required (Tables 1.5 and 1.6). 

FIGURE 1.10 Comparison of calculated and experimental viscosity of crude oil blends, (o) Experimental, (—) REFUTAS method, (-------) Binary interaction parameter. 

The effect of feed was examined with only three points. Moreover, all the feeds come from similar crude oils (blends of Maya and Isthmus oils). For these reasons, it is anticipated that more information is needed for a better ranking of correlations. In spite of this, it can be established that those approaches that include pressure and temperature effects tend to reproduce coking product yields with lower error. 

Crude oil is a mixture of many different hydrocarbons and small amounts of impurities. The composition of crude oil can vary significantly depending on its source. Petroleum refineries are a complex system of multiple operations and the operations used at a given refinery depend upon the properties of the crude oil to be refined and the desired products. For these reasons, no two refineries are alike. Portions of the outputs from some processes are re-fed back into the same process, fed to new processes, fed back to a previous process, or blended with other outputs to form finished products. The major unit operations typically involved at petroleum refineries are described briefly below. In addition to those listed below, there are also many special purpose processes that cannot be... 

Figure 1 shows a simplified flow plan for a typical hydroskimming refinery. The atmospheric pipestill performs the initial distillation of crude oil into gas, naphtha, distillates, and residuum. The naphtha may be separated into gasoline blending stock, solvents, and Powerformer feed. The distillates include kerosene, jet fuel, heating oil and diesel oil. The residuum is blended for use as bunker fuel oil. 

Transportation fuels are the largest consumers of crude oil. Petroleum-based transportation fuels are responsible for 35 percent of greenhouse gas emissions m the United States. Only percent of transportation fuels comes from renewable nonpetro-leum-based sources, primarily from the use of corn-based ethanol blended with gasoline to make gasohol. Increased use of biofuels could lower some of the pollution caused by the use of transportatiou fuels. 

The majority of today s turbines arc fueled wth natural gas or No. 2 distillate oil. Recently there has been increased interest in the burning of nonstandard liquid fuel oils or applications where fuel treatment is desirable. Gas turbines have been engineered to accommodate a wide spectrum of fuels. Over the years, units have been equipped to burn liquid fuels, including naphtha various grades of distillate, crude oils, and residual oils and blended, coal-derived liquids. Many of these nonstandard fuels require special provisions. For example, light fuels like naphtha require modifications Co the fuel handling system to address high volatility and poor lubricity properties. 

It is not possible to make lubricants directly from crude oil that will meet all these demands. Instead, the refinery produces a few basic oils and these are then blended in varying proportions, together with additives when necessary, to produce oil with the particular characteristics... 

Corexit 9527 is a water-and ethylene glycol monobutyl ether-dissolved dispersant. The nature of the surface-active agent has not been disclosed. Laboratory tests were conducted using 0.5-mm thick, fresh Alberta Sweet-Mixed Blend crude oil treated with Corexit 9527 dispersant applied from an overhead spray boom [165]. The effects on dispersion efficiency of mixing jet pressure, mixing jet flow rate, jet standoff distance, and vessel speed were evaluated. The system operates with a nozzle pressure of 7000 kPa, a flow rate of 55 liter/min per nozzle, and nozzles positioned approximately 0.6 m from the water surface. In laboratory tests, such a system was capable of dispersing 80% to 100% of the surface slick. 

Denotes values recorded on blends composed of 2556 by volume crude oil plus 7556 by volume decane... 

After bauxite treatment the product was fractionated to produce C3-C4 and naphtha (C5-204°C) fractions. The C3-C4 olefin-rich gas was oligomerized over a solid phosphoric acid (SPA) catalyst to produce an unhydrogenated polymer gasoline with a research octane number (RON) of 95 and MON of 82.21 The bauxite-treated FT motor gasoline (RON of 87, MON of 76) was mixed with the polymer gasoline and some natural gas condensates (and crude-oil-derived naphtha) to produce the final motor gasoline product. In this respect it is noteworthy that the Fe-HTFT-derived material was the high-octane-blend stock. 

Superficially the Oryx GTL refinery design has much in common with the SMDS process, but there are important differences. There is no separate hydrotreater, which limits production of chemicals, such as waxes. The hydrocracker employs the Chevron Isocracking technology, which is based on a sulfided supported base-metal catalyst that was designed for crude oil conversion. The operating conditions of the hydrocracker are also more severe (>350°C, 7 MPa) than those required by the SMDS process (300-350°C, 3-5 MPa). Only intermediate products are produced (Table 18.13),5 with the naphtha slated as cracker feed and the distillate as blending component for diesel fuel. 

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