This document discusses process integration techniques for optimizing mass and energy usage within chemical processes. It focuses on heat exchange networks (HENs) which identify the optimal matching of hot and cold process streams to minimize utility usage. The document provides an example of constructing composite curves to analyze the minimum hot and cold utility requirements for a system with multiple hot and cold streams. It demonstrates how to determine the pinch temperature and minimum temperature difference between hot and cold streams using these composite curves.

1. SAJJAD KHUDHUR ABBAS
Ceo , Founder & Head of SHacademy
Chemical Engineering , Al-Muthanna University, Iraq
Oil & Gas Safety and Health Professional – OSHACADEMY
Trainer of Trainers (TOT) - Canadian Center of Human
Development
Episode 60 : Pinch Diagram
and Heat Integration

2. 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)

3. 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

4. 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)
Mass
with 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)

5. 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
Plant
Unit Operations
Raw 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 Exchangers
Hot and Cold Utilities
Heat
Exchanger
Network

6. 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 250 120 130
2 Hot 4000 200 100 400
3 Cold 3000 90 150 -180
4 Cold 6000 130 190 -360
-10

7. 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

8. Temperature Interval Diagram (TID)
Hot Temperature Scale Cold Temperature Scale
250 240
200
140
100
190
130
90
160 150
120 110

9. Net Energy Required at Each Interval
Hot Temperature Scale Cold Temperature Scale Heat Duty Within Intervals
Interval, i
250 240FCp 1000 4000 3000 6000 1000 Q
200
140 3 130
100 5
120 4 110
190
90
1 50
2 -40
160 150
-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,ii  hot,i 
Therefore,
i

10. Heat Transfer to and from Utilities for Each Temperature Interval
Hot Temperature Scale
250
Cold Temperature Scale
240
50
200 190
Hot -
40
Cold
160 Utility Utility 150
140 130
120 110
100 20 90

11. Cascade Diagram
Hot Temperature Scale Cold Temperature Scale
250 240
200
140
100
190
150
130 Pinch
90
160
50
-40
-80
50
Hot
Utility
Cold
Utility10
70
0
40 40
20 60

12. 11
Hot Composite Curve
Table 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 80,000
T=140 H2=(1000+4000)(140-120)=100,000 180,000
T=160 H3=(1000+4000)(160-140)=100,000 280,000
T=200 H4=(1000+4000)(200-160)=200,000 480,000
T=200 H5=1000(250-200)=50,000 530,000

13. Hot Composite Curve
270
250
230
210
190
170
150
130
110
90
0 100 200 300 400
Enthalpy, 1000 BTU/hr
500 600
Temperature(degF)

14. Cold Composite Curve
Table 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)=120,000 180,000
T=150 H2=(3000+6000)(150-130)=180,000 360,000
T=190 H3=6000(190-150)=240,000 600,000

15. Cold Composite Curve
210
190
170
150
130
110
90
0 100 200 300 400
Enthalpy, 1000 BTU/hr
500 600 700
Temperature(degF)

16. Composite Curves
270
250
230
210
190
170
150
130
110
90
Temperature,degF
Hot Composite Stream
Cold Composite Stream at 10 deg F
minimum temperature driving force
0 200 400 600
Enthalpy, 1000 BTU/hr
Computer Aided process Engineering - Lecture 11 (R. Gani)

17. Composite Curves
270
250
230
210
190
170
150
130
110
90
Temperature,degF
Hot Composite Stream
Cold 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/hr
Computer Aided process Engineering - Lecture 11 (R. Gani)

18. Composite “Pinch” Diagram
Temperature Minimum
Amount of
Cold Utility
Required
Minimum
Amount of
Hot Utility
Required
Process to Process
Heat Integration
“Pinch” or
Tminimum
Enthalpy
Computer Aided process Engineering - Lecture 11 (R. Gani)

19. Thanks for Watching
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