What are the steps involved in fractional distillation of crude oil?

Answer 1

Fractional Distillation is the separation of a mixture into its component parts, or fractions, such as in separating Chemical_compoundby their Boiling_pointby heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of Distillation. Generally the component parts boil at less than 25 °C from each other under a pressure of one atmosphere (Atmosphere_(unit)). If the difference in boiling points is greater than 25 °C, a Distillationis used. File:Fractional_distillation_lab_apparatus.svgFractional distillation apparatus using a Liebig_condenser. A Conical_flaskis used as a receiving flask. Here the distillation head and Fractionating_columnare combined in one piece.Answers.com

Discussion

As an example, consider the distillation of a mixture of Waterand Ethanol. Ethanol boils at 78.4 °C while water boils at 100 °C. So, by gently heating the mixture, the most volatile component will concentrate to a greater degree in the vapor leaving the liquid. Some mixtures form Azeotrope, where the mixture boils at a lower temperature than either component. In this example, a mixture of 96% ethanol and 4% water boils at 78.2 °C, being more Volatility_(chemistry) than pure ethanol. For this reason, ethanol cannot be completely purified by direct fractional distillation of ethanol-water mixtures.

The apparatus is assembled as in the diagram. (The diagram represents a batch apparatus, as opposed to a continuous apparatus.) The mixture is put into the round bottomed flask along with a few Boiling_chip(or a Teflon coated magnetic stirrer bar if using magnetic stirring), and the fractionating column is fitted into the top. As the mixture boils, vapor rises up the column. The vapor Condensationon the glass platforms, known as Theoretical_tray, inside the column, and runs back down into the liquid below, Refluxdistillate. The column is heated from the bottom. The efficiency in terms of the amount of heating and time required to get fractionation can be improved by insulating the outside of the column in an insulator such as wool, aluminum foil or preferably a vacuum jacket. The hottest tray is at the bottom and the coolest is at the top. At steady state conditions, the vapor and liquid on each tray are at Vapor-liquid_equilibrium. Only the most volatile of the vapors stays in Gasform all the way to the top. The vapor at the top of the column, then passes into the condenser, which cools it down until it liquefies. The separation is more pure with the addition of more trays (to a practical limitation of heat, flow, etc.) The condensate that was initially very close to the azeotrope composition becomes gradually richer in water. The process continues until all the ethanol boils out of the mixture. This point can be recognized by the sharp rise in temperature shown on the Thermometer.

Typically the example above now only reflects the theoretical way fractionation works. Normal laboratory fractionation columns will be simple glass tubes (often vacuum jacketed, and sometimes internally Silvering) filled with a packing, often small glass helices of 4 to 7 mm diameter. Such a column can be calibrated by the distillation of a known mixture system to quantify the column in terms of number of theoretical plates. To improve fractionation the apparatus is set up to return condensate to the column by the use of some sort of reflux splitter (reflux wire, McIntire Head, Magnetic swinging bucket, etc.) - a typical careful fractionation would employ a reflux ratio of around 10:1 (10 parts returned condensate to 1 part condensate take off).

In laboratory distillation, several types of condensers are commonly found. The Liebig_condenseris simply a straight tube within a Water_jacket, and is the simplest (and relatively least expensive) form of condenser. The Graham_condenseris a spiral tube within a water jacket, and the Allihn_condenserhas a series of large and small constrictions on the inside tube, each increasing the surface area upon which the vapor constituents may condense.

Alternate set-ups may utilize a "cow" or "pig" which is connected to three or four receiving flasks. By turning the "cow" or "pig", the distillates can be channeled into the appropriate receiver. A Perkin_triangleis versatile piece of apparatus that can also be used to collect distillation fractions which does not require a "cow" or "pig" adapter. A Perkin_triangleis most often used where the distillates are Air-sensitiveor where the fractions distill and are collected under reduced pressure, but can be used for a simple and fractional distillation.

Vacuum_distillationsystems operate at reduced pressure, thereby lowering the boiling points of the materials. Note that the use of Boiling_chipwill not work at reduced pressures.

Industrial distillationFile:Colonne_distillazione.jpgImage 2: Typical industrial fractional distillation columns

Distillation is the most common form of separation technology used in Oil_refinery, Petrochemicaland Chemical_plantand Natural_gas_processingplants.Answers.comAnswers.comIn most cases, the distillation is operated at a Continuous_distillationSteady_state. New feed is always being added to the distillation column and products are always being removed. Unless the process is disturbed due to changes in feed, heat, ambient temperature, or condensing, the amount of feed being added and the amount of product being removed are normally equal. This is known as continuous, steady-state fractional distillation.

Industrial distillation is typically performed in large, vertical cylindrical columns known as "distillation or fractionation towers" or "distillation columns" with diameters ranging from about 65 centimetres to 6 metres and heights ranging from about 6 metres to 60 metres or more. The distillation towers have liquid outlets at intervals up the column which allow for the withdrawal of different fractions or products having different Boiling_pointsor boiling ranges. By increasing the temperature of the product inside the columns, the different hydrocarbons are separated. The "lightest" products (those with the lowest boiling point) exit from the top of the columns and the "heaviest" products (those with the highest boiling point) exit from the bottom of the column.

For example, fractional distillation is used in Oil_refineryto separate Crude_oilinto useful substances (or fractions) having different Hydrocarbonsof different boiling points. The crude oil fractions with higher boiling points:

• have more Carbon_atom
• have higher Molecular_weight
• are darker in color
• are more Viscosity
• are more difficult to ignite and to Combustion

File:Distillation_Column.pngFigure1: Diagram of a typical industrial distillation tower

Large-scale industrial towers use Refluxto achieve a more complete separation of products. Reflux refers to the portion of the condensed overhead liquid product from a distillation or fractionation tower that is returned to the upper part of the tower as shown in the schematic diagram of a typical, large-scale industrial distillation tower. Inside the tower, the reflux liquid flowing downwards provides the cooling needed to condense the vapors flowing upwards, thereby increasing the effectiveness of the distillation tower. The more reflux is provided for a given number of Theoretical_plate, the better the tower's separation of lower boiling materials from higher boiling materials. Alternatively, the more reflux provided for a given desired separation, the fewer theoretical plates are required.

Fractional distillation is also used in air separation, producing Liquid_oxygen, Liquid_nitrogen, and highly concentrated Argon. Distillation of Chlorosilanealso enable the production of high-purity Siliconfor use as a Semiconductor.

In industrial uses, sometimes a packing material is used in the column instead of trays, especially when low pressure drops across the column are required, as when operating under vacuum. This packing material can either be random dumped packing (1-3" wide) such as Raschig_ringor Structured_packing. Typical manufacturers are Koch, Sulzer and other companies. Liquids tend to wet the surface of the packing and the vapors pass across this wetted surface, where Mass_transfertakes place. Unlike conventional tray distillation in which every tray represents a separate point of Vapor_liquid_equilibriumthe vapor liquid equilibrium curve in a packed column is continuous. However, when modeling packed columns it is useful to compute a number of Theoretical_plateto denote the separation efficiency of the packed column with respect to more traditional trays. Differently shaped packings have different surface areas and void space between packings. Both of these factors affect packing performance.

Design of industrial distillation columnsApparatus

Answer 2

1. where u eat crude oil and get fat and inbred

Answer 3

I don't know! that's why i asked!