Chemical Engineering Separation Processes Quiz

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Questions and Answers

What is the separating agent used in liquid-liquid extraction?

Heat transfer

Stripping vapor

Catalytic converter

Liquid entrainer (correct)

Which separation process is applied in the recovery of aromatics?

Distillation

Catalytic reforming

Leaching

Liquid-liquid extraction (correct)

What is the purpose of leaching as a separation process?

Formation of minimum-boiling azeotropic mixtures

Selective dissolution of components in feed mixture

Promoting diffusion of solute into liquid solvent (correct)

Removing light ends from naphtha, kerosene, and gas oil

What makes liquid-liquid extraction suitable when distillation is impractical?

Temperature sensitivity of the feed mixture Signup and view all the answers

In azeotropic distillation, what role does the liquid entrainer play?

Formation of minimum-boiling azeotropic mixtures Signup and view all the answers

What distinguishes liquid-liquid extraction with two solvents from regular liquid-liquid extraction?

Each solvent having specific selectivity for dissolving components Signup and view all the answers

Which separation process is used for the purification of styrene?

Distillation Signup and view all the answers

In which separation process is a liquid solvent used as the separating agent?

Extractive distillation Signup and view all the answers

Which separation process is suitable for separating carbon dioxide from combustion products?

Absorption Signup and view all the answers

Which separation process involves contacting a liquid feed with a stripping agent?

Stripping Signup and view all the answers

Which separation process is suitable for separating acetone and methanol?

Extractive distillation Signup and view all the answers

Which of the following is a disadvantage of using a mass separating agent (MSA) in separation processes?

All of the above Signup and view all the answers

What is another name for maximum-boiling azeotropes?

Also called maximum-boiling azeotropes Signup and view all the answers

What is the key requirement for the two phases to be separated in a single-stage equilibrium contact process?

The components must have different volatilities Signup and view all the answers

What is the primary purpose of distillation?

To separate a mixture based on differences in boiling points Signup and view all the answers

At what point does a liquid begin to boil?

When the vapor pressure just equals the applied pressure Signup and view all the answers

What is the relationship between the vapor and liquid phases in distillation?

The vapor and liquid contain the same components but in different relative quantities Signup and view all the answers

Study Notes

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

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Description

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.