A hydrocarbon is an organic compound consisting of carbon and hydrogen only. The inclusion of any atom other than carbon and hydrogen disqualifies the compound from being considered as a hydrocarbon. The majority of hydrocarbons found naturally occur in petroleum (crude oil) and natural gas, where decomposed organic matter provides an abundance of many individual varieties of hydrocarbons. A refinery consists of many processes that convert crude oils into valuable products such as gasoline, jet fuel and diesel by consuming of hydrogen, etc. The required hydrogen in some processes can be supplied from other processes which are producers of hydrogen.
