Heat Integration

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Heat Integration
An Introduction to Heat Exchanger Network (HEN)
Design
By Anwaruddin Hisyam
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In this lecture we will learn how to set energy
recovery targets for a process.
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Pinch identification
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Base case
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Data Extraction
178 C
880
1620
180 C
160 C
60 C
2640
130 C
210 C
270 C
Reactor
160 C
210 C
149 C
1220
1980
50 C
220 C
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..from data extraction
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Stream Data (Problem Table)
No T source, C T target, C Heat duty, kW CP Type
1 220 60 3520 22 Hot
2 270 160 1980 18 Hot
3 50 210 3200 20 Cold
4 160 210 2500 50 Cold
CP Heat duty/ABS(T source T target)
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Composite Curve
DT min
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Set DTmin 20 C
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Shifted Stream DataHot - ½DTmin Cold ½DTmin
No T source, C T target, C Heat duty, kW CP Type
1 210 50 3520 22 Hot
2 260 150 1980 18 Hot
3 60 220 3200 20 Cold
4 170 220 2500 50 Cold
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Shifted Composite Curve
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Cascade Diagram
Cold-Hot
Hot
Cold
Stream population
0 720 -720 SURPLUS
700 180 520 DEFICIT
2800 1600 1200 DEFICIT
400 800 -400 SURPLUS
1800 1980 -180 SURPLUS
0 220 -220 SURPLUS
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Heat balance in the interval
Hot utility
Heat flow
-720
520
1200
-400
-180
-220
Cold utility
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The heat flow must NOT be negative
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Normalization
Need additional heat
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Original Grand Composite Curve
Unfeasible region
Feasible region
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finding pinch
No heat flow at this point
Eureka....! This is the PINCH
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Grand Composite Curve
Qh min
Qc min
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finally.The PINCH POINT 170 Cwhich means
thatHot stream PINCH 170½DTmin 180 Cold
stream PINCH 170-½DTmin 160
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Heat source and sink

• Heat source ? this part releases heat
• Heat sink ? this part requires heat

PINCH
Heat Source
Heat Sink
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and, how can we design HEN based on the pinch?
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Base case.the existing network
Heat recovery 1980 880 2860 kW Cold utility
2640 kW Hot utility 1220 1620 2840 kW
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Lets start from the pinch
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(No Transcript)
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Rules.

• CP in CP out
• Start finding partners for streams OUT (with
  streams IN, away from pinch, or utility)
• N stream IN N stream out
• If Ns IN gt Ns OUT, split stream(s) OUT
• If CP in gt CP out (no match), try to split
  stream(s) IN
• Set maximum heat recovery
• The remaining heat duty is covered by heater or
  cooler

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Step 1 Below the PINCH Connect S1(22) and
S3(20) CP in lt CP out
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Step 2 Above the PINCH Connect S2(18) and
S4(50) CP in lt CP out
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Step 3 Above the PINCH Connect S1(22) and
S4(50) CP in lt CP out
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Step 4 Above the PINCH Install Heater at S3(20)
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Step 5 Below the PINCH Install Cooler at S1(22)
and S2(18)
440
880
v
180
v
C
1
3
2640
60
220
880
360
1620
180
v
v
C
2
360
160
1620
270
1000
v
160
v
H
1
2200
50
210
1000
2200
160
v
2
3
210
160
2500
All heat requirements have been met !!!
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finallyHeat Exchanger Network (HEN)
Maximum Energy Recovery (MER) 2200 880 1620
4700 kW Minimum cooling heat duty (Qc min)
440 360 800 kW Minimum heating heat duty (Qh
min) 1000 kW
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Then draw the flowsheet
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Possible modifications
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Grand Composite Curve
MP steam
Heat generation
Cooling water
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Thank you
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Working Session
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How will the HEN be.?