A chemical plant is an industrial process plant that manufactures (or otherwise processes) chemicals, usually on a large scale.
The general objective of a chemical plant is to create new material wealth via the chemical or biological transformation and or separation of materials. Chemical plants use specialized equipment, units, and technology in the manufacturing process. Other kinds of plants, such as polymer, pharmaceutical, food, and some beverage production facilities, power plants, oil refineris, natural gas processing and biochemical plants, use many technologies that have similarities to chemical plant technology such as fluid systems and chemical reactor systems.
Petrochemical plants (plants using chemicals from petroleum as a raw material or feedstock) are usually located adjacent to an oil refinery to minimize transportation costs for the feedstocks produced by the refinery.
Oil refinery is an industrial process plant where crude oil is transformed and refined into more useful products such as petroleum, naphtha, gasoline, diesel fuel, kerosene, jet fuel and fuel oils. Petrochemicals feed stock like ethylene and propylene can also be produced directly by cracking crude oil without the need of using refined products of crude oil such as naphtha.
Petroleum refineries are very large industrial complexes that involve many different processing units and auxiliary facilities such as utility units and storage tanks. Each refinery has its own unique arrangement and combination of refining processes largely determined by the refinery location, desired products and economic considerations. An oil refinery is considered an essential part of the downstream side of the petroleum industry.