Unit processes

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Related to Unit processes: Unit operations

Unit processes

Processes that involve making chemical changes to materials, as a result of chemical reaction taking place. For instance, in the combustion of coal, the entering and leaving materials differ from each other chemically: coal and air enter, and flue gases and residues leave the combustion chamber. Combustion is therefore a unit process. Unit processes are also referred to as chemical conversions.

Together with unit operations (physical conversions), unit processes (chemical conversions) form the basic building blocks of a chemical manufacturing process. Most chemical processes consist of a combination of various unit operations and unit processes.

The basic tools of the chemical engineer for the design, study, or improvement of a unit process are the mass balance, the energy balance, kinetic rate of reaction, and position of equilibrium (the last is included only if the reaction does not go to completion). See Chemical engineering, Unit operations

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The system is comprised of four unit processes: pretreatment under anaerobic conditions, ultrafiltration, air stripping and absorption, and reverse osmosis.
It covers the history of process modeling; modeling fundamentals; various models available for different unit processes, including biofilm models, and their advantages and disadvantages; process modeling software tools; dedicated experiments and modeling tools that can be used during specific phases of the modeling process, especially the calibration step; available modeling and simulation protocols; defining the objectives of the model for a project; building a facility model; and using models for design, optimization, and control.
Then, an inventory modeling is performed by identifying the unit processes of the two systems and tracking and quantifying the environmental (material, primary energy, air emissions, etc.) and economic flows (transportation, electricity, etc.) associated with the unit processes.
The Crime Scene Unit and Latent Print Unit processes about 800 latent fingerprint assignments a year.
Following fairly standard manufacturing process for electrodeposited wafer bumping, the unit processes include wafer cleaning, micro back-etch, UBM/seed layer metal deposition, photoresist development and patterning, electroplating of the copper and the solder cap, resist stripping, visual inspection and solder reflow.
While super users and end users may be familiar with unit processes and workflow, they may not be comfortable speaking in front of others or leading a class.
With IVA, the unit processes video signals and automatically alerts operators to potential security risks.
For automotive coatings, three unit processes represent the majority of environmental impacts: pretreatment, E-coat, and topcoat.
With the intention of helping readers attain such skills as flowcharting, performing degree of freedom analyses, identifying possible systems and subsystems, and applying the first law of thermodynamics, they describe real balanced and single unit processes, multiple unit process calculations, balances and reactive processes, multiple systems involving reaction recycling and purging, energy balance without reaction, energy balance with three actions, combined material and energy balances, unsteady state material and energy balances.
The business unit processes more than 12 billion financial and clinical transactions each year.