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Instrumentation andControl

Introduction

Haseeb Ullah Khan Jatoi

Department of ChemicalEngineering

UET Lahore

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Controller

Final Control

Element

Measuring

Element

rocess

Desired !alue

inputs outputs

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Control "b#ecti!es$

%& 'afet(

)& En!ironmental rotection

*& E+uipment rotection

,& 'mooth lant "peration and roduction -ate.& roduct /ualit(

0& ro1t "ptimi2ation

3& Monitoring and Diagnosis

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Control can be$

• "pen loop

• Closed loop

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Control T(pes

• Feedbac4 Control

• Feedfor5ard Control

•

Cascade Control

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Feedbac4 Control

 TT

Controller

steam

Heat e6changer

Finalcontrolelement

'ensor7Temperature Transmitter8

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Feed for5ard Control

 TTController

steam

Heat e6changer

Finalcontrolelement

'ensor7Temperature Transmitter8

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E6ample

steam

F9 T

Fi9 Ti

h

Fst

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 The control ob#ecti!es of this heater are$%& To 4eep the e:uent temperature T at the

desired !alue Ts

)& To 4eep the !olume of the li+uid in the tan4

at a desired !alue ;s&

 The operation of the heater is disturbed b(e6ternal factors such as changes in the feed

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F9 T

Fi9 Ti

 Thermocouple

Controller

'et>point

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F9 T

Fi9 Ti

 Thermocouple

Controller

'et>point

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F9 T

Fi9 TiLe!el Measuring

De!ice

Controller

hs

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F9 T

Fi9 TiLe!el Measuring

De!ice

Controller

hs

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F9 T

Fi9 Ti

Controller

FT

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For this e6ample?

• Input ;ariables are$ Fi9 Ti and Fst

75hich denote the e@ect ofsurroundings on the process8

• "utput ;ariables are$ F9 ; and T

75hich denote the e@ect of processon the surroundings8