Furnace oil is a dark colored fuel, either distilled or residual fraction of crude oil that is extracted while petroleum distillation and is used for the purpose of generation heat and power. This fuel is sticky, thick and glutinous in nature. Furnace oil is known by the name of fuel oil internationally and also as bunker fuel. The fuel oil consists of lengthy chains of hydrogen and carbon mainly alkanes, cycloalkanes and aromatics. Basically furnace oil is termed for relatively heavier commercial extracts from crude oil.
Fuel oil (also known as heavy oil, marine fuel or furnace oil) is a fraction obtained from petroleum distillation, either as a distillate or a residue. In general terms, fuel oil is any liquid fuel that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash point of approximately 42°C (108°F) and oils burned in cotton or wool-wick burners.
Furnace oil is largely an industrial fuel. It acts as a key ingredient in the generation of electricity and heat in a number of production units. It has been used since a long time for such purposes and has gained much importance and inevitable value. Fuel oil comes under the category of the heavier oils that include furnace oil, low sulfur heavy stock, residual fuel oil, lube oil, bitumen, petroleum coke, paraffin wax and other waxes which can be extracted from crude oil.