Episode 60 : Pinch Diagram and Heat Integration
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Transcript of Episode 60 : Pinch Diagram and Heat Integration
SAJJAD KHUDHUR ABBASCeo , Founder & Head of SHacademyChemical Engineering , Al-Muthanna University, IraqOil & Gas Safety and Health Professional – OSHACADEMYTrainer of Trainers (TOT) - Canadian Center of Human Development
Episode 60 : Pinch Diagram and Heat Integration
Introduction of Process Integration
Pinch Diagram and Heat Integration
Reference: Notes from course on “Modelling, design and control for process integration”, CAPEC, August 2000 (R.
Dunn)
Process Integration Tools Allow Analysis of the “Enterprise”
• The optimal allocation of mass and energy within a unit operation, process and/or site.• Optimal allocation can be based on economic, environmental or other important objectives.
Heating Cooling
Mass Integration (Mass Exchange Network – MEN) Energy Integration (Heat Exchange Network – HEN)
Power Pressure
ProductsFeed Stock
By-ProductsSolvents
Chemical Plant
(Enterprise)Effluents
Catalysts
Spent MaterialsMaterial for Utilities(Water, Coal)
Heating Power Cooling
Pressure
Process Integration Techniques
ReactiveMass Exchange ExchangeNetworks Networks(REAMEN’s)
Mass Exchange Networks (MEN’s)
Process Integration
Process Integration
Heat Exchange Networks (HEN’s)
Combined Heat and Reactive Mass Exchange Networks (CHARMEN’s)
Masswith Regeneration (MEN/REGEN)
Reverse Osmosis Networks (RON’s)
Heat-Induced
Waste Minimization Networks (HIWAMIN’s)
Energy-Induced Separation Networks (EISEN’s)
Pervaporation Network’s (PERVAP’s) Waste
Interception and Allocation Networks(WIN’s)
Heat-Induced Separation Networks (HISEN’s)
Energy-Induced Waste Minimization Networks (EIWAMIN’s)
4
Heat Exchange Network (HEN)
Want to Identify:– Optimal matching between hot and cold streams to
minimize utility consumption– Minimum number of heat exchangers needed
PlantUnit OperationsRaw Materials
Products&
By-Products
Hot Streams In
Cold Streams In
Cold Streams Out
Hot Streams Out
(Linnhoff, Grossmann et al, 1978-Present)A Heat Exchange Network is a System of One or More
Heat ExchangersHot and Cold Utilities
Heat Exchanger Network
Therefore, 10x103 BTU/hr must be supplied from utilities (if there are no restrictions on temperature driving force)
How can we check driving force restrictions? Second Law Analysis (You can not transfer heat from a lower temperature to a higher temperature)
5*Ref. Douglas, 1988, Conceptual Design of Chemical Processes, McGraw-Hill Publishers, p. 218.
Consider the problem of two hot stream and two cold streams:
First Law Analysis (Conservation of Energy):
Q F Cp T 4000 BTU (200 100)o F 400x103 BTU / hr hr o F
Q FCp T 1000 BTU (250 120)o F 130x103 BTU / hr hr o F
2 2 2 2
1 1 1 1
Calculate Q3 and Q4
Table 1*
Stream Q available
No. Condition FCp, BTU/(hroF) Tin Tout 103 BTU/hr
1 Hot 1000 250 120 1302 Hot 4000 200 100 4003 Cold 3000 90 150 -1804 Cold 6000 130 190 -360
-10
Shifted Temperature Scales (using Table 1 data):
100
Hot Temperature Scale Cold Temperature Scale
250
240
200
150
190
140
90
Sources Sinks
These streams need to be cooled
These streams need to be heated
Temperature Interval Diagram (TID)
Hot Temperature Scale Cold Temperature Scale
250
240
200
140
100
190
130
90
160 150
120 110
Net Energy Required at Each Interval
Hot Temperature Scale Cold Temperature Scale
Heat Duty Within IntervalsInterval, i250 240FCp 1000 4000 3000 6000 1000 Q
200
140 3 130
100 5
120 4 110
190
90
1 50
2 -40160 150
-80
40
20
Total = -10
Q (FCp) (FCp)
T
Q (1000 4000 3000 6000)(160 140) 80x103
3
Q (1000 4000 6000)(200 160) 40x103
2
Q (1000)(250 200) 50x103
1
cold ,i
i hot ,i
Therefore,
i
Heat Transfer to and from Utilities for Each Temperature IntervalHot Temperature Scale
250
Cold Temperature Scale
240
50200 190
Hot -40
Cold160
UtilityUtility 150
140 130
120 110
100 20 90
Cascade Diagram
Hot Temperature Scale Cold Temperature Scale
250 240
200
140
100
190
150
130 Pinch
90
160
50
-40
-80
50Hot
UtilityCold
Utility10700
40 4020 60
11
Hot Composite CurveTable 2*
Hot streams, oF Cumulative H
Since FCp values are constant, we could have replaced the calculation for H2, H3, H4 with a single expression: H2,3,4=(1000+4000)(200-120)=400,000
Temperature (oF) Plot Becomes the Hot Composite Curve
Enthalpy (1000 BTU/hr)*Ref. Douglas, 1988, Conceptual Design of Chemical Processes, McGraw-Hill Publishers, p. 218.
T=100 H0=0 0
T=120 H1=4000(120-100)=80,000 80,000T=140 H2=(1000+4000)(140-120)=100,000 180,000T=160 H3=(1000+4000)(160-140)=100,000 280,000T=200 H4=(1000+4000)(200-160)=200,000 480,000T=200 H5=1000(250-200)=50,000 530,000
Hot Composite Curve
270
250
230
210
190
170
150
130
110
900 100 200 300 400
Enthalpy, 1000 BTU/hr
500 600
Tem
pera
ture
(deg
F)
Cold Composite CurveTable 2.3*
Cold streams, oF Cumulative H
Temperature (oF) Plot Becomes the Cold Composite Curve
Enthalpy (1000 BTU/hr)
*Ref. Douglas, 1988, Conceptual Design of Chemical Processes, McGraw-Hill Publishers, p. 218.
T=90 H0=60,000 60,000
T=130 H1=3000(130-90)=120,000 180,000T=150 H2=(3000+6000)(150-130)=180,000 360,000T=190 H3=6000(190-150)=240,000 600,000
Cold Composite Curve
210
190
170
150
130
110
900 100 200 300 400
Enthalpy, 1000 BTU/hr500 600 700
Tem
pera
ture
(deg
F)
Composite Curves
27025023021019017015013011090
Tem
pera
ture
, deg
F
Hot Composite StreamCold Composite Stream at 10 deg F minimum temperature driving force
0 200 400 600
Enthalpy, 1000 BTU/hrComputer Aided process Engineering - Lecture 11 (R. Gani)
Composite Curves
270
250
230
210
190
170
150
130
110
90
Tem
pera
ture
, deg
F
Hot Composite StreamCold Composite Stream at 10 deg F minimum temperature driving force Cold Composite Stream at 20 deg F minimum temperature driving force
0 200 400 600
Enthalpy, 1000 BTU/hrComputer Aided process Engineering - Lecture 11 (R. Gani)
Composite “Pinch” Diagram
Temperature Minimum Amount ofCold Utility Required
Minimum Amount of Hot Utility Required
Process to Process Heat Integration
“Pinch” orTminimum
EnthalpyComputer Aided process Engineering - Lecture 11 (R. Gani)
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