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Separation Process EngineeringCHEN 312•Instructor:YousefSalameh,PhD,Chemical Engineering, FS1 402, ext 3602,email:[email protected]•Textbook:Wankat, Phillip C. Separation ProcessEngineering, Third Edition, PearsonEducation, Inc., New Jersey, 2011.ISBN: 0-13-279021-1
Introduction•Separations are crucial in chemical engineering. A typicalchemical plant is a chemical reactor surrounded by separators,where raw materials are prepurified in separation devices and fedto the reactor; unreacted feed is separated from the reactionproducts and recycled back to the reactor.•Chemical plants commonly have from 40% to 70% of both capitaland operating costs in separations.•Separation processes can involve two phases (gas and liquid,liquid and solid, gas and solid or two immiscible liquids)•Relatively easy to separate two phases due to density difference.•Difficult to separate components from a single phase.
•Aim of most processes designed to separate a mixture ofcomponents is to get the components into different phasesand then to separate the phases.Functions of separation processes•Purification: undesired components in the feed mixture areremoved from the desired species.•Concentration:higherconcentrationofthedesiredcomponents, which are initially dilute, are obtained.•Fractionation: two or more components are segregated intoproduct streams of different composition.
For a separation to occur there must be a difference in either achemical or physical property between the various components ofthe feed stream. This difference is the driving force basis for theseparation.Differences are either:–Equilibrium based–Rate basedIf two phases are at equilibrium, the temperatures, pressures andfractions of them cease to change. Although molecules keepmoving from one phase to another, but in the same rate.
The equilibrium stage concept is applicable when the processcan be constructed as a series of discrete stages in which the twophases are contacted and then separated. The two separatedphases are assumed to be in equilibrium with each other.This simplifies the design and analysis of chemical engineeringseparations and unifies the basic design principles and methods fora given separation method (unit operation).Unit Operations is a method of analysis and design of chemicalengineering processes in terms of individual tasks/operations.- It is a way of organizing chemical engineering knowledge intogroups of individual tasks/operations.