2- Unit Operatios

8/14/2019 2- Unit Operatios

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Feed

Product

cooling water or

steam outlet

Feed

UNIT OPERATIONS

Chemical Engineering Equipment

Reactors

Tubular catalytic reactor

Jacketed reactor

Continuous stirred tank reactor

Mixing

In industrial process engineering, mixingis a unitoperation that involves manipulating a heterogeneous

physical system, with the intent to make it more

homogeneous.

Product

coolant

reactants


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Divider/Splitter

Composition of

streams A, B and C is

the same for each.

Mixer (Blender)

There are two or

more entering

streams and onlyone exit stream, a

"mixed" stream.

Propeller agitatedtank

Turbine agitatedtank

Gassparger

Splitter Feed, A

Splitter Exit 1, B

Splitter Exit 2, C

MIXER

Mixer Feed 2,

B

Mixer Feed 1, F Mixer Product,


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Separation Processes

Liquid-Liquid

Separation

y Distillation

y Extraction

y Decanting

y Coalescing

Gas-Solid Separation

y Filtration

y

Cyclonesy Settling

y Centrifugation

Solid-Solid Separation

y Screening

y Cyclones

y Flotation

y Flocculation

Solid-Liquid

Separations

y Evaporation

y Crystallization

y Sedimentation

y Filtrationy Centrifugation

Gas-Gas Separation

y

Absorptiony Adsorption

Liquid-Gas Separation

y

S

tripping


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Liquid-Liquid Separation

Distillation Column

Used primarily for

liquid-liquid

separations

Based on differences

in boiling points ofcomponents

Partial Condenser

Can have trays or packed

columns

e.g. Solvent recovery

A + B

Liquid A

(some B

Condenser

Reboiler

Liquid B(some A)

PartialC ndenser

Vapor Feed, F

Vap rPr d ct, V

C ndensed Liq id, L


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a.The feed stream contains only condensable vaporcomponents.

b.The exit streams, L and V, are in equilibrium.c.Condensation is caused by cooling and/or increasing

pressure.

Flash Vaporizer, Flash Distillation

a. Same flow sheet as a partial condenser except thefeed is a liquid.

b. Vaporization is caused by reducing the pressureand /or heating.

c. The Vapor and liquid streams are in equilibrium.

Liq id Feed, F

Vap rPr d ct, V

Flash

Unit

Liq id Pr d ct, L


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Liquid-liquid Extraction

method to separate compounds based on their solution

preferences for two different immiscible liquids,usually water, and an organic solvent. It is an

extraction of a substance from one liquid phase into

another liquid phase.

Mixer Settlers are a class of process equipment used in

the solvent extraction process. A mixer settler

consists of a first stage that mixes the phases togetherfollowed by a quiescentsettlingstage that allows the

phases to separate by gravity

Mixer Decanter or settler

Purified FeFeed Solvent + soluteExtract Solvent

Extract Solvent

+ solute


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Solid-Liquid SeparationsEvaporatorsUsed to separate materials based on differences in

boiling temperatures

CrystallizersUsed in liquid-solid separations to produce salts and

chemicals in industry

Sand Filters

B in liquid A

concentrated

solution of B in A

A (crystals)

e.g. Crystallizers create a super-

saturated solution by evaporating

the solvent of a saturatedsolution. The solute cools,

forming crystals.

Liquid A + B

(concentration ofB is higher inoutlet than inlet)

Used in industry toconcentrate fruit juices(remove excess water)

Vapour A

Liquid A + B


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Solid-Liquid and Solid-Gas Separations

Cyclone separator

Plate and

frame filterClarifier or

thickener

Centrifugal

separator

Screen

Utility

Electrostatic

precipitator or

bag filter

Continuous

process filter


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Solid-liquid Extraction (Leaching)

is the process of extracting a substance from a solid bydissolving it in a liquid. In the chemical processing

industry, leaching is known as extraction. Leaching

has a variety of commercial applications, including

separation of metal from ore using acid, and sugar

from beets using hot water.


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Liquid-Gas Separation

Stripper (Gas Desorption)

Brings gas and liquid in contact so that volatile

contaminants in the liquid will be stripped into the gas

(i.e. liquid purification)

Soluble gas transferred from liquid phase to gas phase

because the activity (concentration) in the liquid phase

is greater

e.g. Removal of benzene

from groundwater

solute-free Liquid

Liquid+solutegas+solute

gas


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Gas-Gas Separation

Absorbers

Bring a gas and

liquid in contact so

that contaminants in

the gas will absorb

into the liquid

(used to purify gasstreams)

Adsorber

Separation of a substance from one phase, with its

accumulation at the surface of another phase (material

from the liquid is concentrated on the surface of the

solid)

e.g. Carbon cartridges in gasmasks remove harmful gasese.g. Silica gel is used as adrying agent

Liquid A + B

Solid C

Liquid A

(Usually C is stationary)

Solid C with B

Liquid

Liquid + solute

Purified gas

gas + solute


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Dryers

Moisture is removed thermally from a liquid-solid

mixture

Humidifiers

Used to increase the relative humidity of air (i.e. toadd moisture to the air)

e.g. Conveyor dryers used

in food applications (drying

chips or pastas)

A (liq)B (solid)

B (solid),

some A

C + A

C (gas)

Liquid B

Gas A

Gas A and BUsed in paper and leather

industries to prevent

products from becoming

brittle and dry


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Dehumidifier

Used to remove one component from a gas stream

Heat Transfer Equipment

y Feed streams have to be heated/cooled

y Product streams have to be heated/cooled

y Materials have to be maintained at a specifictemperature e.g. in a reactor

Types

Shell and tube; Double pipe; Compact;

Reboiler; Condenser

Shell and tube

heat exchanger

Kettle

reboiler Condenser

B is a condensable gas

e.g. removing water from

air (i.e. creating a drier air)

Gas A and B

Gas A (may stillbe some B)

Liquid B

10

1 2

3

4


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Fluid-Moving Equipment

Centrifugal

Fan

Axial

Fan

Turbine

CentrifugalPump

ReciprocatingPump

Propeller

Boiler FurnaceCooling

tower

RATA T

OB: BY

C e

C&P 613

ettle Reboiler Fire eater Air cooler

Air

Cooler


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Towers

Packed Tray SprayS parged G

Piston

Compressor

Rotary

Blower

Axial

Compressor


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Storage Tanks and Vessels

Drums

Hold-up drumFlash drum

General General Furnace-

type

Reactor


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Heated Vessels

Gas-Solid Contacting Equipment

Fluidized

bedVertical

tower

Rotary

drum

Continuoustunnel

Horizontal

jacketedVertical

jacketed

Submerged

coil


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Size-Modification Equipment

Drum

agglomerator

Pellet

mill

Extruder Roller

crusher

Documents

2- Unit Operatios