unit operations

unit operations

[′yü·nət ‚äp·ə′rā·shənz]
(chemical engineering)
The basic physical operations of chemical engineering in a chemical process plant, that is, distillation, fluid transport, heat and mass transfer, evaporation, extraction, drying, crystallization, filtration, mixing, size separation, crushing and grinding, and conveying.

Unit operations

A structure of logic used for synthesizing and analyzing processing schemes in the chemical and allied industries, in which the basic underlying concept is that all processing schemes can be composed from and decomposed into a series of individual, or unit, steps. If a step involves a chemical change, it is called a unit process; if physical change, a unit operation. These unit operations cut across widely different processing applications, including the manufacture of chemicals, fuels, pharmaceuticals, pulp and paper, processed foods, and primary metals. The unit operations approach serves as a very powerful form of morphological analysis, which systematizes process design, and greatly reduces both the number of concepts that must be taught and the number of possibilities that should be considered in synthesizing a particular process.

Most unit operations are based mechanistically upon the fundamental transport processes of mass transfer, heat transfer, and fluid flow (momentum transfer). Unit operations based on fluid mechanics include fluid transport (such as pumping), mixing/ agitation, filtration, clarification, thickening or sedimentation, classification, and centrifugation. Operations based on heat transfer include heat exchange, condensation, evaporation, furnaces or kilns, drying, cooling towers, and freezing or thawing. Operations that are based on mass transfer include distillation, solvent extraction, leaching, absorption or desorption, adsorption, ion exchange, humidification or dehumidification, gaseous diffusion, crystallization, and thermal diffusion. Operations that are based on mechanical principles include screening, solids handling, size reduction, flotation, magnetic separation, and electrostatic precipitation. The study of transport phenomena provides a unifying and powerful basis for an understanding of the different unit operations. See Absorption, Centrifugation, Chemical engineering, Clarification, Cooling tower, Crystallization, Dehumidifier, Drying, Filtration, Flotation, Heat exchanger, Humidification, Kiln, Leaching, Magnetic separation methods, Mechanical separation techniques, Mixing, Pump, Pumping machinery, Sedimentation (industry), Solids pump, Solvent extraction, Unit processes

References in periodicals archive ?
It is our practice not to comment on specific unit operations at our facilities.
We believe we are in the best position to optimize our customers' hydroprocessing unit operations.
Drioli, Di Profio, and Curcio describe the ongoing efforts to introduce a new design for crystallization, one of the most important unit operations in chemical processing.
What are the unit operations I must have and in what order?
The three-day technical course addressed current best practices in unit operations with a focus on systems integration, economic sustainability, process improvement, cost reduction and the use of practical safety as a part of daily work behavior.
As an undergrad, I learned the most in a unit operations class and in my instrumentation classes.
This research examines the effect of using mechanical equipment for the unit operations involved in gari (cassava flakes) processing on individual and total energy demands.
Unit operations of particulate solids; theory and practice.
RMBAM on the other hand boasts a significant increase in assets under management that exceed the N$5 billion mark in the past financial year Picture: (Left to right) Lesley Rukoro, CEO of RMBAM, Conrad Wood, head of fixed interests at RMBAM, Edison Katjipuka, chief operating officer of FNB unit trusts and Priscilla Denk, team leader of FNB trust unit operations (Photograph contributed)
As a full-fledged workstation, FlexAct allows for the design of efficient and flexible processes by using out of the box disposable unit operations.
There are many different unit operations associated with the conversion of raw food materials into consumer products.
Furthermore, it allows direct benchmark comparisons among unit operations across an entire company, supporting daily decisions to improve plant operations and to make high-level business assessments, such as those regarding capital spending, at the corporate level.

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