Archive for September, 2009

Straight Run Kerosene

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This fraction is usually the first side stream of a conventional atmospheric distillation unit. It may be cut to meet a burning oil specification or become a component in Jet Fuel finished product. Its cut range is usually between 360?F and 480?F. Again this cut range may vary with the required heavy end of the …

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Naphthas

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Naphthas

There are usually two naphtha cuts produced from most crude. These are: Light naphtha (sometimes called light gasoline) Heavy naphtha. Both these streams are the bottom product of the debutanizer unit. They are separated in a naphtha splitter fractionation tower. The light naphtha contains most of the crude’s C5’s and much of the paraffin portion …

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Refinery Gas and LPGs

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Refinery Gas and LPGs

In many refineries most of theC4’s and lighter are removed from the atmospheric column overhead distillate in the first column of the light end unit. This is the unit’s debutanizer column. Some refineries however chose to separate the light naphtha and lighter from the heavy naphtha first. There is no specific reason one can assume …

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Atmospheric Overhead Distillate

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Atmospheric Overhead Distillate

This is not strictly a cut but consists of all the light material in the crude absorbed into the total overhead distillate from the crude tower. This distillate, and in most cases, together with similar distillates from other processes form the feed to the refinery’s light end unit. It is in the light end unit …

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Vacuum Residue

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Vacuum Residue

This is the bottom product from the vacuum distillation unit. Just as in the case of the atmospheric residue it has several options for its use in meeting the refinery’s product slate. In the case of the energy refineries it can be upgraded to prime distillate products by a recycling thermal cracking process, coking, deep …

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Vacuum Distillation of Atmospheric Residue

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Vacuum Distillation of Atmospheric Residue

In modern refinery practice the distillation of atmospheric residue is accomplished under high vacuum conditions in a specially designed tower whose internal equipment ensures a very lower pressure drop. Normally the vacuum conditions in the flash zone of the tower allows about the same percentage of distillate based on the tower feed to be cut …

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Atmospheric Residue

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Atmospheric Residue

This is the bottom product from the atmospheric distillation of the crude oil. Most crude oils are distilled in the atmospheric crude oil tower to cut the atmospheric residue at a +650?F up to a +680?F cut point. Cutting the residue heavier than +680?F risks the possibility of cracking with heavier coke lay down and …

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Moody Friction Factor

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Moody Friction Factor

The factor of proportionality in the previous equations is called the  Moody friction factor and is determined from the Moody resistance diagram shown in Figure 8-1. The friction factor is sometimes expressed in terms of the Fanning friction factor, which is one-fourth of the Moody friction factor. In some references the Moody friction factor is …

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Darcy’s Equation

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Darcy’s Equation

This equation, which is also sometimes called the Weisbach equation or the Darcy-Weisbach equation, states that the friction head loss between two points in a completely filled, circular cross section pipe is proportional to the velocity head and the length of pipe and inversely proportional to the pipe diameter. This can be written: Equations 8-5 …

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Bernoulli’s Theorem

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Bernoulli’s Theorem

It is customary to express the energy contained in a fluid in terms of the potential energy contained in an equivalent height or “head” of a column of the fluid. Using this convention, Bernoulli’s theorem breaks down the total energy at a point in terms of 1. The head due to its elevation above an …

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