Chemical engineering is the branch of engineering that applies the physical sciences (e.g., chemistry and physics) and/or life sciences together with mathematics and economics to processes that convert raw materials or chemicals into more useful or valuable forms. In addition, modern chemical engineers are also concerned with pioneering valuable materials and related techniques - Within chemical engineering, two broad subgroups include
1) design, manufacture, and operation of plants and machinery in industrial chemical and related processes ("chemical process engineers"); and
2) development of new or adapted substances for products ranging from foods and beverages to cosmetics to cleaners to pharmaceutical ingredients, among many other products.
Chemical engineering involves the application of several principles. Key concepts are presented below.
Chemical reactions engineering involves managing plant processes and conditions to ensure optimal plant operation. Chemical reaction engineers construct models for reactor analysis and design using laboratory data and physical parameters, such as chemical thermodynamics, to solve problems and predict reactor performance
Chemical engineering design concerns the creation of plans and specification, and income projection of plants. Chemical engineers generate designs according to the client's needs. Design is limited by a number of factors, including funding, government regulations and safety standards. These constraints dictate a plant's choice of process, materials and equipment.
A unit operation is a physical step in an individual chemical engineering process. Unit operations (such as crystallization, drying and evaporation) are used to prepare reactants, purifying and separating its products, recycling unspent reactants, and controlling energy transfer in reactors. On the other hand, a unit process is the chemical equivalent of a unit operation. Along with unit operations, unit processes constitute a process operation. Unit processes (such as nitration and oxidation) involve the conversion of material by biochemical, thermochemical and other means. Chemical engineers responsible for these are called process engineers.