Mechanical Separations Lecture_01

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This presentation is the first part of series of lecture prepared for Mechanical Separations which is taught as a subject in Chemical Engineering. This Lecture # 1 includes Introduction to Separation Process focusing on Mechanical Separations.

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Lecture # 1 : 

Lecture # 1 September 14, 2010 1 MECHANICAL SEPARATIONS Prepared by: A.N.Tabish Lecturer MECHANICAL SEPARATIONS (Ch.E-207) Department of Chemical Engineering University of Engineering & Technology, Lahore -Pakistan Introduction to Mechanical Separations

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September 14, 2010 MECHANICAL SEPARATIONS 2 Course Outline: Ch.E-207 MECHANICAL SEPARATIONS Introduction to separation processes; Role of mechanical separations in chemical processing; Fundamentals of the following Mechanical Separations; Filtration, Sedimentation, Clarification, Flotation, Centrifugal Separations, Jigging, Tabling, Magnetic and Electrostatic Separations, Sonic Agglomeration; Different type of Filters, Cyclones, Centrifuges, Flotation cells, Electrostatic Precipitators, Magnetic Separators and settling tanks with emphasis on the followings; Mechanical Construction, Operation and the working principle, design and the controlling parameters, efficiency, economic evaluation, applications and the selection criteria.

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September 14, 2010 MECHANICAL SEPARATIONS 3 Ch # 5: Sedimentation Ch # 7: Liquid Filtration Ch # 9: Centrifugal Separations Reference Books: J.M. Coulson, & J.F. Richardson, “Coulson & Richardson’s Chemical Engineering” , Vol. 2, Ed. 5, Butterworth Heinemann. Inc

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September 14, 2010 MECHANICAL SEPARATIONS 4 Reference Books: Ch # 1: Solid-Liquid Filtration Technology Ch # 2: Filtration Fundamentals Ch # 3: Sedimentation Fundamentals Ch # 4: Filter Media Ch # 5: Clarifying Filtration Ch # 8: Centrifugal Separation Ch # 11: Filtration Process Equipments and Calculations

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September 14, 2010 MECHANICAL SEPARATIONS 5 Ch # 1: Introduction to Solid-Liquid Separation Ch # 7: Separation by Centrifugal sedimentation Ch # 9: Filtration fundamentals Ch # 10: Cake Washing Ch # 12: Pressure Filtration Ch # 13: Vacuum Filtration Ch # 14: Centrifugal Filtration Ch # 17: The selection of Solid-Liquid equipments Reference Books:

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September 14, 2010 MECHANICAL SEPARATIONS 6 Reference Books: Section 17: Gas-Solid operations and Equipments Cyclone Separators Electrical Precipitators Section 18: Liquid-Solid operations and Equipments Gravity Sedimentation Operations Filtration Centrifuges Section 19: Solid-Solid operations and Equipments Jigging Tabling

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September 14, 2010 MECHANICAL SEPARATIONS 7 Reference Books: Ch # 6: Mechanical Separation Equipments Filtration Equipment Sedimentation Equipment Centrifugal Separation Equipment

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September 14, 2010 MECHANICAL SEPARATIONS 8 Reference Books: Ch # 11: Solid-Liquid Separations Theory of Filtration Problems related to filtration Filtration Equipment Sedimentation Equipment Classification Equipment Centrifugal Equipment

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September 14, 2010 MECHANICAL SEPARATIONS 9 Separation : A technique that transform a mixture of substances into two or more products differing in composition.

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September 14, 2010 MECHANICAL SEPARATIONS 10 Need of Separation Processes: The ever-increasing demands on product purity, particularly in the pharmaceutical, biotechnology and food industries, The gradual reduction in the quality of raw materials, this being a particularly serious problem in mineral processing, The growing demands for environmental acceptability of waste materials. Chemical Reactions Separation of chemicals Separation of phases Key operations in Chemical Plant:

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September 14, 2010 MECHANICAL SEPARATIONS 11 Need of Separation Processes:

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September 14, 2010 MECHANICAL SEPARATIONS 12 Separation of Manufacturing Process:

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September 14, 2010 MECHANICAL SEPARATIONS 13 13

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September 14, 2010 MECHANICAL SEPARATIONS 14 Separation in Petroleum Refinery:

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September 14, 2010 MECHANICAL SEPARATIONS 15 Mechanism of Separation: Mixing: Spontaneous process Increases randomness and entropy (Second Law of Thermodynamic) No energy requirement Separation: Non-Spontaneous process Attempt to decrease entropy, increase order and against to Second Law of Thermodynamic Separation mechanism (Energy flow/mechanical work) requirement

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September 14, 2010 MECHANICAL SEPARATIONS 16 Mechanism of Separation: Separating Agents: Energy input (heat, pressure, electricity, magnetism, kinetic or potential energy) Withdrawal of energy (cooling, freezing) Matter (filter, membrane, chemicals)

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September 14, 2010 MECHANICAL SEPARATIONS 17 Mechanism of Separation: Separation by phase creation Separation by phase addition

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September 14, 2010 MECHANICAL SEPARATIONS 18 Mechanism of Separation:

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September 14, 2010 MECHANICAL SEPARATIONS 19 Mechanism of Separation:

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September 14, 2010 MECHANICAL SEPARATIONS 20 Classification of Separation Technology:

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September 14, 2010 MECHANICAL SEPARATIONS 21 Separation Processing: Mass Transfer Operations: Mechanical Separations: Classification of Separation Technology: Distillation Absorption Stripping Adsorption Liquid-Liquid Extraction Drying Evaporation Crystallization Leaching Ion Exchange Filtration Ultra-filtration Sedimentation Centrifugal Separation Flotation Electrostatic Precipitation Jigging Tabling Sonic Agglomeration Membrane Separation

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September 14, 2010 MECHANICAL SEPARATIONS 22 1. Filtration (Mechanical Separations) : Filtration is a mechanical or physical operation which is used for the separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass.

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September 14, 2010 MECHANICAL SEPARATIONS 23 2. Ultra-Filtration (Mechanical Separations) : Ultra-filtration (UF) is a variety of membrane filtration in which hydrostatic pressure forces a liquid against a semi permeable membrane. Suspended solids and solutes of high molecular weight are retained, while water and low molecular weight solutes pass through the membrane.

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September 14, 2010 MECHANICAL SEPARATIONS 24 3. Sedimentation (Mechanical Separations) : Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are entrained, and come to rest against a barrier.

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September 14, 2010 MECHANICAL SEPARATIONS 25 4. Centrifugal Separation (Mechanical Separations) : Centrifugal Separation is the separation technique in which mixture of substances having different densities is separated by applying centrifugal force.

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September 14, 2010 MECHANICAL SEPARATIONS 26 5. Flotation (Mechanical Separations) : The process of separating different materials, especially minerals, by agitating a pulverized mixture of the materials with water, oil, and chemicals. Differential wetting of the suspended particles causes unwetted particles to be carried by air bubbles to the surface for collection.

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September 14, 2010 MECHANICAL SEPARATIONS 27 Electrostatic precipitation is defined as the use of an electrostatic field for precipitating or removing charged solid or liquid particles from a gas stream in which the particles are carried in suspension. 6. Electrostatic Precipitation (Mechanical Separations) :

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September 14, 2010 MECHANICAL SEPARATIONS 28 7. Jigging (Mechanical Separations) : A gravity based separation method which separates mineral from gangue particles by utilizing an effective difference in settling rate through a periodically dilated bed. It is simply a method of pulsed shaking which allows heavier minerals to settle.

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September 14, 2010 MECHANICAL SEPARATIONS 29 Separation of two materials of different densities by passing a dilute suspension over a slightly inclined table having a reciprocal horizontal motion or shake with a slow forward motion and a fast return. 8. Tabling (Mechanical Separations) :

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September 14, 2010 MECHANICAL SEPARATIONS 30 9. Sonic Agglomeration (Mechanical Separations) : The union of small particles suspended in a fluid medium into larger aggregates by the action of sound waves is called sonic agglomeration.

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September 14, 2010 MECHANICAL SEPARATIONS 31 Mechanical Separations: Mechanical separation operations depend on differences in bulk properties, such as density or particle size, to bring about the separation of different components of a mixture. Mechanical Separations in Food Industry: Some specific examples for foods include: Clarification of juices, Wine and beer; Removal of excess pulp from fruit juice; Separation of solvents from oil seed meal; Separation of water from oils; Removal of dust from air;

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September 14, 2010 MECHANICAL SEPARATIONS 32 Advantages/Dis-advantages of Mechanical Separations: Relatively less Energy Requirements (Utilities) Ease of Operation Ease of Maintenance (But not in all) No special Feed pretreatment required Not applicable for separating Components in homogeneous phase They are not versatile i.e. in same state may be one element can be separated and other can not Applicable to low flow rates Advantages: Dis-Advantages:

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September 14, 2010 MECHANICAL SEPARATIONS 33 Factors Effecting the Selection of Separation Process:

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September 14, 2010 MECHANICAL SEPARATIONS 34 tabish288@yahoo.com

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