Chemical Engineering Separation Processes Quiz

Separation Techniques

• Separating agent: Stripping vapor (MSA)
• Example: Stream stripping of naphtha, kerosene, and gas oil side cuts from crude distillation unit to remove light ends

Azeotropic Distillation

• Formation of minimum-boiling azeotropic mixtures
• Separating agent: Liquid entrainer (MSA) and heat transfer (ESA)
• Example: Separation of acetic acid from water using n-butyl acetate as entrainer to form azeotrope with water

Liquid-Liquid Extraction

• Widely used when distillation is impractical, especially for temperature-sensitive mixtures
• Separating agent: Liquid solvent (MSA)
• Example: Recovery of Aromatics

Liquid-Liquid Extraction (Two Solvents)

• Each solvent has its own specific selectivity for dissolving the components of the feed mixture
• Separating agent: Two liquid solvents (MSA1 and MSA2)
• Example: Use of propane and cresylic acid as solvents to separate paraffins from aromatics and naphthenes

Leaching

• Referred to as solid-liquid extraction
• Widely used in metallurgical, natural product, and food industries
• Separating agent: Liquid solvent
• Example: Extraction of sucrose from sugar beets with hot water

Disadvantages of MSA

• Need for additional separator to recover the MSA for recycle
• Need for MSA makeup
• Possible contamination of the product with the MSA
• More difficult design procedures

Distillation

• Most widely utilized industrial separation technique
• Involves multiple contacts between counter currently flowing liquid and vapor phases
• Separating agent: ESA and sometimes work transfer
• Example: Purification of styrene

Extractive Distillation

• Used when volatility differences between species to be separated are small
• Separating agent: Liquid solvent (MSA) and heat transfer (ESA)
• Example: Separation of acetone and methanol

Absorption

• Used when the feed is all vapor and the stripping section of the column is not needed
• Separating agent: Liquid absorbent (MSA)
• Example: Separation of carbon dioxide from combustion products by absorption with aqueous solutions of an ethanolamine

Stripping

• A liquid mixture is separated by contacting liquid feed with a stripping agent
• Also called maximum-boiling azeotropes
• Example: Water and ethanol

Single-Stage Equilibrium Contact for Vapor-Liquid System

• Two different phases are brought into intimate contact with each other and then are separated
• The components have different volatilities so that they will partition between the two phases to different extents
• The two phases can be separated by gravity or other mechanical means

Basic Distillation Setup

• Distillation is a method of separating mixtures based on differences in volatility of the components in a boiling liquid mixture
• It is a unit operation, or a physical separation process, and not a chemical reaction
• A vapor contacts a liquid, and mass is transferred both from the liquid to the vapor and from the vapor to the liquid

Test your knowledge on various chemical engineering separation processes such as Azeotropic Distillation and Liquid-Liquid Extraction. Learn about separating agents like stripping vapor, liquid entrainer, and heat transfer methods.