CRUDE OILCrude oil is a flammable liquid found in subterranean deposits and best known for its use as a fuel and as a raw material for chemical products.It was originally created from the remains of animals and plants that lived in a water environment. Millions of years ago, much of the earth was covered by seas- more than it is today. Countless millions of tiny creatures and plants lived in these seas. When they died they sank to the bottom, and as the years passed more and more piled up on the sea bed. Silt and sand piled up with them, and the whole lot was pressed firmly down by later layers over the centuries. The terrific pressure of these layers, and of the water on top of them, generated heat. This heat together with other chemical action, affected the remains of the animals and plants. It turned them into a substance called crude oil.The principal constituents of crude oil are compounds of hydrogen and carbon known chemically as hydrocarbons, the boiling point of a hydrocarbon depends on its chain length, the longer the chain the higher the boiling point. The variation in the boiling points of the hydrocarbons in crude oils allows them to be separated by fractional distillation. Besides hydrocarbons, crude oil contains organic sulfur, oxygen and nitrogen compounds, metals and salts.·Carbon - 84%·Hydrogen - 14%·Sulfur - 1 to 3% (hydrogen sulfide, sulfide's, disulfides, elemental sulfur)·Nitrogen - less than 1% (basic compounds with amine groups)·Oxygen - less than 1% (found in organic compounds such as carbon dioxide, phenol's, ketones, carboxylic acids)·Metals - less than 1% (nickel, iron, vanadium, copper, arsenic)·Salts - less than 1% (sodium chloride, magnesium chloride, calcium chloride)On average, crude oils are made of the following elements or compoundsThe properties of crude oil are extremely diverse. They vary in viscosity from thick black tarry asphalt, such as those found in the asphalt lake of Trinidad and the Athabascan tar sands of Canada, to the light volatile oils found in the Kettleman Hills district of Calafornia, which can be used directly as gasoline. In between are oils of all colours, odours and variations in boiling range and chemical composition. In colour they maybe yellow, green, amber, cherry red, reddish brown, dark brown, or black, and some fluoresce green or purple in reflected light. In odour some are ethereal and pleasant, some smell sweet and others have a very bad odour, usually because of the presence of certain sulfur compounds.Fractional DistillationThe 'crude' oil which comes out of the ground is a mixture of many substances, it must me refined before it can be used as a fuel or in the manufacture of other products, because of their different boiling points they can be separated easily by heating the crude oil and drawing it off at different fractions. Industrial distillation towers for petroleum often have over 100 plates, with as many as ten different...
