?Crude Oil Properties:
Crude petroleum is very complex and, except for the low-boiling components, no attempt is made by the refiner to analyze for the pure components contained in the crude oil. Relatively simple analytical tests are run on the crude and the
results of these are used with empirical correlations to evaluate the crude oils as feedstocks for the particular refinery.
Each crude is compared with the other feedstocks available and, based upon the operating cost and product realization, is
assigned a value. The more useful properties are discussed.
API Gravity
The density of petroleum oils is expressed in the United States in terms of API gravity rather than specific gravity; it is related to specific gravity in such a fashion that an increase in API gravity corresponds to a decrease in specific gravity.
The units of API gravity are °API and can be calculated from specific gravity by the following:
In this equation, specific gravity and API gravity refer to the weight per unit volume at 60°F as compared to water at 60°F.
API gravities are not linear and, therefore, cannot be averaged. For example, a gallon of 30°API gravity hydrocarbons when mixed with a gallon of 40°API hydrocarbons will not yield two gallons of 35°API hydrocarbons, but will give two gallons of
hydrocarbons with an API gravity different from 35°API. Specific gravities can be averaged.
?Using the following formula, API gravity can also be used to calculate how many barrels of crude oil can be produced per metric ton.
Barrels of crude oil per metric ton = 1 / [141.5 / (API gravity + 131.5) x 0.159]
Example: How many barrels per metric ton of West Texas Intermediate crude oil (with an API of 39.6)?
A metric ton of West Texas Intermediate, with an API of 39.6, will produce 7.6 barrels (at 42 gallons each).
Carbon Residue, wt%
Carbon residue is determined by distillation to a coke residue in the absence of air. The carbon residue is roughly related to the asphalt content of the crude and to the quantity of the lubricating oil fraction that can be recovered.
In most cases the lower the carbon residue, the more valuable the crude. This is expressed in terms of the weight percent carbon residue by either the Ramsbottom (RCR) or Conradson (CCR) ASTM test procedures (D-524 and D-189).
Salt Content, lb/1000 bbl
If the salt content of the crude, when expressed as NaCl, is greater than 10 lb/1000 bbl, it is generally necessary to desalt the crude before processing. If the salt is not removed, severe corrosion problems may be encountered.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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