![]() In general, unit operations are designed by writing down the balances for the transported quantity for each elementary component (which may be infinitesimal) in the form of equations, and solving the equations for the design parameters, then selecting an optimal solution out of the several possible and then designing the physical equipment. This is usually necessary for designing catalytic reactions, and is considered a separate discipline, termed chemical reaction engineering.Ĭhemical engineering unit operations and chemical engineering unit processing form the main principles of all kinds of chemical industries and are the foundation of designs of chemical plants, factories, and equipment used. A "pure" unit operation is a physical transport process, while a mixed chemical/physical process requires modeling both the physical transport, such as diffusion, and the chemical reaction. Separation ( distillation, crystallization)įurthermore, there are some unit operations which combine even these categories, such as reactive distillation and stirred tank reactors.Mechanical processes, including solids transportation, crushing and pulverization, and screening and sieving.Ĭhemical engineering unit operations also fall in the following categories which involve elements from more than one class:.Thermodynamic processes, including gas liquefaction, and refrigeration.Mass transfer processes, including gas absorption, distillation, extraction, adsorption, and drying.Heat transfer processes, including evaporation and heat exchange.Fluid flow processes, including fluids transportation, filtration, and solids fluidization. ![]() The unit operations form the fundamental principles of chemical engineering.Ĭhemical engineering unit operations consist of five classes: For instance, the same engineering is required to design a mixer for either napalm or porridge, even if the use, market or manufacturers are very different. Each unit operation follows the same physical laws and may be used in all relevant chemical industries. They summed up these similar processes into unit operations. McAdams wrote the book The Principles of Chemical Engineering and explained that the variety of chemical industries have processes which follow the same physical laws. Arthur Dehon Little developed the concept of "unit operations" to explain industrial chemistry processes in 1916. Historically, the different chemical industries were regarded as different industrial processes and with different principles. A process may require many unit operations to obtain the desired product from the starting materials, or feedstocks. These unit operations are connected to create the overall process. For example, in milk processing, the following unit operations are involved: homogenization, pasteurization, and packaging. Unit operations involve a physical change or chemical transformation such as separation, crystallization, evaporation, filtration, polymerization, isomerization, and other reactions. In chemical engineering and related fields, a unit operation is a basic step in a process. An ore extraction process broken into its constituent unit operations ( Quincy Mine, Hancock, MI ca.
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