Week 6 Q2
Stream
Type
TS (oC)
TT (oC)
H
(kW)
C=m*Cp (kJ/h C)
1
H1
Hot
180
40
280
7.2E03
2
H2
Hot
150
40
440
14.4E03
3
C1
Cold
60
180
360
10.8E03
4
C2
Cold
30
130
260
9.36E03
Tin
Tout
*C
Tmin
: Source temperature
: Target temperature
: Heat capacity flow rate ( mCp = Energy/Temperature)
: 10oC
*C is assumed to be constant with temperature
Launch Aspen Energy Analyzer
Starting the Heat Integration Manager…
Click Managers Menu and
Click on Heat Integration Manager
1. Select HI Case from Heat Integration Manager
2. Click Add… button
HI Case: Case 1 Display
*Save your file as AEA or another name of your choice
Enter Process Stream Data
• Enter Entalphy data for each stream and MCp will be calculated.
• You cannot enter Enthalphy and MCp at the same time
• HTC use as is unless you have actual process stream values
Add Utility Streams
*Choose HP(High Pressure) Steam because need > 180OC
*Choose Cooling Water 20OC (Europe/North America).
Now Hot and Cold box turns green and displayed Sufficient
Change Cooling Water Temperature
•
•
•
•
Change Inlet T = 30oC and Out T = 50oC
More reflective of tropical temperature conditions
Increasing outlet temperature to T = 50oC will reduce target flowrate significantly
7650 kg/h vs 1913 kg/h of cooling water
Click on Open Targets View menu
HI Case: Case 1 Targets
Aspen energy Analyzer will calculate the following:
•
•
•
•
Energy Targets (Heating and Cooling)
Minimum Heat exchanger for MER
Pinch Temperatures
Cost Index (Useful but beyond scope of course)
Composite Curve
• Click on Plots/Tables Tab
• Do not forget to enlarge the view to see the Composite Curves clearly
Grand Composite Curve
Open HEN Grid Diagram
Close previous windows and click on the Open HEN Grid Diagram button
Open HEN Diagram Properties View
• Please check the stream are ordered in terms of temperature – important!
• Red ‐ Hot stream and Blue – Cold stream
• Click Preset 1: (Temperature, No. Util.)
Showing Pinch Line
Above Pinch
Below Pinch
Adding Heat Exchangers
• Right click mouse button and drag the icon
Add Heat Exchanger E‐100
C=2
C=4
C=3
C = 2.6
Satisfy Above Pinch Criteria: Ccold > Chot  3 > 2
Heat Exchanger E‐100 details
• Duty and Area for the heat exchanger
• Only temperatures meeting the Tmin are allowable
Heat Exchanger E‐100 Connectivity
• How the hot and cold stream are connected to the new
exchanger is shown here
Add Heat Exchanger E‐101
C=2
C=4
C=3
C = 2.6
Satisfy Below Pinch Criteria: Ccold < Chot  2.6 < 4
Heat Exchanger 101 details
Heat Exchanger 101 Connectivity
Add Heat Exchanger E‐102
C=2
C=4
C=3
C = 2.6
Satisfy Below Pinch Criteria: Ccold < Chot  3 < 4
Heat Exchanger 102 details
Heat Exchanger 102 Connectivity
Add Heat Exchanger E‐103
C=2
C=4
C=3
C = 2.6
Below Pinch : Ccold < Chot  3 > 2. OK not next to Pinch
Heat Exchanger 103 details
Heat Exchanger 103 Connectivity
Add Heat Exchanger E‐104
C=2
C=4
C=3
C = 2.6
Below Pinch : Ccold < Chot  3 < 4
Heat Exchanger E‐104 details
Heat Exchanger E‐104 Connectivity
Add Heat Exchanger E‐105
C=2
C=4
C=3
C = 2.6
Ccold < Chot  2.6 > 2, OK not next to Pinch
Heat Exchanger E‐105 details
Heat Exchanger E‐105 Connectivity
Show Utility Streams
• Click on Open HEN Diagram Properties View
• Choose Preset 4: (Temperature)
• Now you can see the Hot and Cold utilities
Add Heat Exchanger E‐106
• Connect stream Cooling Water to stream H2 utility to get Heat Exchanger E‐106
Heat Exchanger E‐106 details
Heat Exchanger E‐106 Connectivity
Add Heat Exchanger E‐107
• Connect stream C1 to HP steam utility to get Heat Exchanger E‐107
Heat Exchanger E‐107 details
Heat Exchanger E‐107 Connectivity
Graphical Solution
• Click on the Show/Hide Pinch Lines to hide the line
Worksheet Solution
• Click on the Work Sheet Tab
Comparison
Energy Targets
Heating (kJ/h)
360000
60000
Cooling(kJ/h)
440000
Total Required
HP Steam
Cooling Water
160000
Obtained from HEN
300000
280000
Savings (%)
83.33
63.64
Total Heat Exchanger Area
AEA
Proposed HEN
6.98
26.20
1.09
13.36
22.02
27.55
11.95
18.10
Total Area (m2)
Deviation
Percent Deviation
131.03
127.24
‐3.78
‐2.89
Number of Unit Targets
AEA
Proposed HEN
Minimum for MER
6
8