Introduction


 * Fouling in General **

==== In heat exchangers, when fluids interact with the material used for construction of the heat exchanger, some materials would deposit onto the surface of heat exchangers. The deposition of materials on the surface of heat transfer devices is called fouling. This deposition would form a coat on the surface, which would increase the resistance of the heat flow. Also the deposits on the surface of heat exchangers would potentially increase the pressure drop. As a result, fouling would not only greatly hinder the performance of heat exchangers, but also lead to a safety concern to the working environment. ====

[[image:fouling.gif width="501" height="327" caption="Figure1: fouling"]]

 * Crude Oil Fouling **

Crude oil is generally known as “petroleum”, which is a fossil fuel composes of carbon, hydrocarbon, organic and inorganic elements or compound. Crude oil varies in color from clear to black. Crude oil is very useful starting material because it contains different types of hydrocarbons, which could generally be isolated trough distillation.

The process of fractional distillation is based on the concept of boiling point of different substance. Each substance (hydrocarbon) would have a unique boiling point, and could be separated by boiling the crude oil. The separated hydrocarbon would then be made into different products such as petrol for vehicles, jet fuel, diesel fuels, bitumen, etc.

==== In crude oil processing operations (e.g.fractional distillation), fouling specifically refers to the deposition of heavy hydrocarbons (asphaltenes, waxes, etc), and the cause of fouling is mainly due to the impurities of crude oil. Since fouling is the inescapable consequence of heat transfer and would greatly influence the productivity and efficiency of crude oil heat exchangers, it is necessary to conduct fouling control in every heat exchanger. ====

Table 1: Crude Oil Components
 * Components || Percentage (%) ||
 * Carbon || 84 ||
 * Hydrogen || 14 ||
 * Sulfur (hydrogen sulfide, sulfides, disulfides, sulfur element) || 1-3 ||
 * Nitrogen (compounds with amine groups) || Less than 1 ||
 * Oxygen (within carbon dioxide, ketones, carboxylic acids, phenols) || Less than 1 ||
 * Metals (iron, copper, vanadium, nickel) || Less than 1 ||
 * Salts (sodium chloride, calcium chloride) || Less than 1 ||

