Heat Integration
description
Transcript of Heat Integration
Pinch technology series 1
By:
Anwaruddin Hisyam
An Introduction to An Introduction to
Heat Exchanger Network (HEN) Heat Exchanger Network (HEN) DesignDesign
Pinch technology series 2
In this lecture we will learn how to set energy recovery targets for a process.
Pinch technology series 3
Pinch identificationPinch identification
Pinch technology series 4
Base case
Reactor
50 C
160 C270 C210 C
210 C
220 C
180 C60 C
130 C
149 C
1620
2640
19801220
178 C
160 C
880
Pinch technology series 5
Data Extraction
Reactor
50 C
160 C270 C210 C
210 C
220 C
180 C60 C
130 C
149 C
1620
2640
19801220
178 C
160 C
880
Pinch technology series 6
…..from data extraction
Reactor
50 C
160 C270 C210 C
210 C
220 C 60 C
130 C
160 C
Pinch technology series 7
Stream Data (Problem Table)
NoT source,
CT target,
CHeat duty,
kWCP 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)
Pinch technology series 8
Composite Curve
Composite Curve
0
50
100
150
200
250
300
0 1000 2000 3000 4000 5000 6000 7000
Heat duty (kW)
Tem
p in
terv
al (
K) DT min
Pinch technology series 9
Set DTmin = 20 CSet DTmin = 20 C
Pinch technology series 10
Shifted Stream DataHot - ½DTmin; Cold + ½DTmin
NoT source,
CT target,
CHeat duty,
kWCP 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
Pinch technology series 11
Shifted Composite Curve
Shifted Composite Curve
050
100150200250300
0 1000 2000 3000 4000 5000 6000 7000
Heat Duty (kW)
Tem
p in
terv
al (
K)
Pinch technology series 12
Cascade Diagram
0 720 -720 SURPLUS
700 180 520 DEFICIT
2800 1600 1200 DEFICIT
400 800 -400 SURPLUS
1800 1980 -180 SURPLUS
0 220 -220 SURPLUS
22
18
20
50
260
220
210
170
150
60
50
Cold HotCold-HotStream population
Pinch technology series 13
Heat balance in the interval
260
220
210
170
150
60
50
0
720
200
- 1000
- 600
- 420
- 200
Hot utility
-720
520
1200
-400
-180
-220
Cold utility
Heat flow
Pinch technology series 14
The heat flow must NOT be negative
Pinch technology series 15
Normalization
260
220
210
170
150
60
50
0
720
200
- 1000
- 600
- 420
- 200
Hot utility
-720
520
1200
-400
-180
-220
Cold utility
Need additional
heat
Pinch technology series 16
Original Grand Composite Curve
0
50
100
150
200
250
300
-1200 -1000 -800 -600 -400 -200 0 200 400 600 800 1000
Unfeasible region
Feasible region
Pinch technology series 17
…finding pinch
260
220
210
170
150
60
50
1000
1720
1200
0
400
580
800
Hot utility
-720
520
1200
-400
-180
-220
Cold utility
No heat flow at this point
Pinch technology series 18
Grand Composite Curve
0
50
100
150
200
250
300
0 500 1000 1500 2000
Heat duty (kW)
Tem
p in
terv
al (K
)
Qh min
Qc min
Pinch technology series 19
finally….finally….The PINCH POINT = 170 CThe PINCH POINT = 170 C
which means thatwhich means that
Hot stream PINCH = 170+Hot stream PINCH = 170+½DTmin = 180½DTmin = 180
Cold stream PINCH = 170-Cold stream PINCH = 170-½DTmin = 160½DTmin = 160
Pinch technology series 20
Heat source and sink
Heat source this part releases heat
Heat sink this part requires heat
Composite Curve
0
50
100
150
200
250
300
0 1000 2000 3000 4000 5000 6000 7000
Heat duty (kW)
Tem
p in
terv
al (K
)
PINCH
Heat Source Heat Sink
Pinch technology series 21
and, and, how can we design HEN how can we design HEN
based on the pinch?based on the pinch?
Pinch technology series 22
Base case….the existing network
Heat recovery = 1980 + 880 = 2860 kW
Cold utility = 2640 kW
Hot utility = 1220 + 1620 = 2840 kW
22060
270160
21050
160
210H
C
H H
2640
1620
880
1980
1220
Pinch technology series 23
Let’s start from Let’s start from the pinchthe pinch
Pinch technology series 24
22060
270160
21050
160
210
180
180
160
160
2200
PIN
CH
AT
170
0
360
2640
1000
2500
1640
880
20
50
18
22
CPBELOW ABOVE
Pinch technology series 25
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 > Ns OUT, split stream(s) OUT
If CP in > CP out (no match), try to split stream(s) IN Set maximum heat recovery The remaining heat duty is covered by heater or
cooler
Pinch technology series 26
22060
270160
21050
160
210
1
180
2200
1
180
160
160
2200 √√
Step 1: Below the PINCH
Connect S1(22) and S3(20)
CP in < CP out
Pinch technology series 27
22060
270160
21050
160
210
1
180
2200
1
180
160
160
2200 √√
2
2
1620√√1620
Step 2: Above the PINCH
Connect S2(18) and S4(50)
CP in < CP out
Pinch technology series 28
22060
270160
21050
160
210
1
180
2200
1
180
160
160
2200 √√
2
2
1620√√1620
3
3
880
880
√√
2500√√
Step 3: Above the PINCH
Connect S1(22) and S4(50)
CP in < CP out
Pinch technology series 29
22060
270160
21050
160
210
1
180
2200
1
180
160
160
2200 √√
2
2
1620√√1620
3
3
880
880
√√
2500√√
H
1000
1000√√
Step 4: Above the PINCH
Install Heater at S3(20)
Pinch technology series 30
22060
270160
21050
160
210
1
180
2200
1
180
160
160
2200 √√
2
2
1620√√1620
3
3
880
880
√√
2500√√
H
1000
1000√√
C
C
360
360
2640
440
√√
√√
Step 5: Below the PINCH
Install Cooler at S1(22) and S2(18)
All heat requirements have been All heat requirements have been met !!!met !!!
Pinch technology series 31
22060
270160
21050
160
210
H
2200
440
1000
1620
880
C
360
C
…finally…Heat 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
Pinch technology series 32
Then draw the flowsheet…
Reactor
50 C
160 C
270 C210 C
210 C220 C
60 C
130 C
160 C
880
1620
2200440
360
1000
177.6 C
180 C
180 C
80 C
160 C
Pinch technology series 33
Possible modifications
Pinch technology series 34
Grand Composite Curve
0
50
100
150
200
250
300
0 500 1000 1500 2000
Heat duty (kW)
Tem
p in
terv
al (K
)
Heat generation
Cooling water
MP steam
Pinch technology series 35
Pinch technology series 36
Working Session Working Session
Pinch technology series 37
Feed 2
Feed 1
H= 27 MW
H=32 MW
H= -31.5 MW
H=-30 MW
140 C
250 C
230 C
40 C
40 C
40 C
180 C
20 C
200 C
80 C
Product 2
Product 1
Reactor 1
Reactor 2
How will the HEN be….?