Chemical Engineering is the design and maintenance of chemical plants and the development of chemical processes for converting raw materials or chemicals into valuable forms including those used to remove chemicals from waste materials, to enable largescale manufacture. It combines knowledge of Chemistry and Engineering for the production of chemicals and related by-products. 
This branch of engineering is a varied field, covering areas from biotechnology and nanotechnology to mineral processing. It covers various fields of chemical technology in mineral based industries, petrochemical plants, pharmaceuticals, synthetic fibres, petroleum refining plants etc. Chemical engineers design and operate chemical plants and improve methods of production.