water pinch (full)
DESCRIPTION
Water PinchTRANSCRIPT
Water Pinch AnalysisWater Pinch AnalysisWater Pinch AnalysisWater Pinch Analysis
Dominic FOO, PhD, PEngDept of Chem & Env Eng
University of Nottingham Malaysia
Copyright@Dominic Foo Pinch Analysis for Water Recovery 2
About myselfAbout myselfAbout myselfAbout myself
� Current position: Associate Professor (University Nottingham Malaysia Campus)
� Qualifications:�BEng (Chemical) (Hons.) (UTM)
�MEng (Chemical) (UTM)
�PhD (Chemical Engineering) (UTM)
� Areas of work:�Research (material recovery, process design &
integration)
�Education (undergraduate/post graduate/ profession training)
�Advice for career & professional development
Copyright@Dominic Foo Pinch Analysis for Water Recovery 3
Talk outlineTalk outlineTalk outlineTalk outline
� Domestic & industrial water usage
� Water pinch analysis
�Graphical targeting for water reuse/recycle
�Nearest neighbour algorithm for network design
�Algebraic targeting for water reuse/recycle & regeneration
� Conclusion
Copyright@Dominic Foo Pinch Analysis for Water Recovery 4
Residential water useResidential water useResidential water useResidential water use
Copyright@Dominic Foo Pinch Analysis for Water Recovery 5
Water usage in our daily lifeWater usage in our daily lifeWater usage in our daily lifeWater usage in our daily life
Flower watering
(3 minutes, 120 Litres)
Teeth brushing
(5 minutes, 45 Litres)
Shower
(5 minutes, 200 Litres)
Hand washing
(2 minutes, 18 Litres)
(Sin Chew Jit Pow, 8 Oct 2003)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 6
Water usage in our daily lifeWater usage in our daily lifeWater usage in our daily lifeWater usage in our daily life
Toilet flushing
(13.5 Litres / flush)
Washing machine
(2 days once, 130 Litres)
Washing plates
(15 minutes, 135 Litres)
Car wash (with host)
(10 minutes, 400 Litres)
(Sin Chew Jit Pow, 8 Oct 2003)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 7
(Smith, 2005)
Water use in process plantWater use in process plantWater use in process plantWater use in process plant
Copyright@Dominic Foo Pinch Analysis for Water Recovery 8
Conventional water networkConventional water networkConventional water networkConventional water network
Process 1
Process 2
Process 3
Process 4
Wastewater
112.5 t/h
Fresh water
112.5 t/h
20.0 t/h
30.0 t/h
37.5 t/h
5.0 t/h
Copyright@Dominic Foo Pinch Analysis for Water Recovery 9
(Wang & Smith, 1994, 1995)
Better water utilisation schemesBetter water utilisation schemesBetter water utilisation schemesBetter water utilisation schemes
Process 1
Process 2
RegenerationProcess 1
Process 2
Regeneration
Regeneration-reuse Regeneration-recycling
Process 1
Process 2
Reuse
Process 1
Recycle
Copyright@Dominic Foo Pinch Analysis for Water Recovery 10
Limiting composite curveLimiting composite curveLimiting composite curveLimiting composite curveLimiting composite curveLimiting composite curveLimiting composite curveLimiting composite curve
2 7 37 41
C (ppm)
∆m (kg/h)
100
400
800
50
456
Process 3
Process 1
Process 2
Process 4
Copyright@Dominic Foo Pinch Analysis for Water Recovery 11
Mass transferMass transferMass transferMass transferMass transferMass transferMass transferMass transfer--------based operationbased operationbased operationbased operationbased operationbased operationbased operationbased operation
Water for vessel washing
Wastewater generated from washing process
Vessel
Washing
Sour gas
Water
Sour water for regeneration
Sweet gasAbsorption
Copyright@Dominic Foo Pinch Analysis for Water Recovery 12
NonNonNonNonNonNonNonNon--------mass transfer processesmass transfer processesmass transfer processesmass transfer processesmass transfer processesmass transfer processesmass transfer processesmass transfer processes
Boiler blowdownBoiler
Cooling tower make-up water
Cooling
tower
Utility make-up & blowdown
O2
NH3
C3H6
AN + H2O
C6H5NO2
Fe
H2O
C6H5NH2 +
Fe3O4
Reactant & by-product formation
Aniline production Acrylonitrile production
Copyright@Dominic Foo Pinch Analysis for Water Recovery 13
An An An An An An An An AcrylonitrileAcrylonitrileAcrylonitrileAcrylonitrileAcrylonitrileAcrylonitrileAcrylonitrileAcrylonitrile ““““““““ANANANANANANANAN”””””””” PlantPlantPlantPlantPlantPlantPlantPlant
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam-jet Ejector
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Copyright@Dominic Foo Pinch Analysis for Water Recovery 14
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam-jet Ejector
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
A poor recycleA poor recycleA poor recycleA poor recycleA poor recycleA poor recycleA poor recycleA poor recycle
Copyright@Dominic Foo Pinch Analysis for Water Recovery 15
FW elimination in scrubber ?FW elimination in scrubber ?FW elimination in scrubber ?FW elimination in scrubber ?FW elimination in scrubber ?FW elimination in scrubber ?FW elimination in scrubber ?FW elimination in scrubber ?
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam-jet Ejector
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Copyright@Dominic Foo Pinch Analysis for Water Recovery 16
FW elimination in the boiler?FW elimination in the boiler?FW elimination in the boiler?FW elimination in the boiler?FW elimination in the boiler?FW elimination in the boiler?FW elimination in the boiler?FW elimination in the boiler?
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam-jet Ejector
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Copyright@Dominic Foo Pinch Analysis for Water Recovery 17
FW elimination in both scrubber FW elimination in both scrubber FW elimination in both scrubber FW elimination in both scrubber FW elimination in both scrubber FW elimination in both scrubber FW elimination in both scrubber FW elimination in both scrubber & boiler ?& boiler ?& boiler ?& boiler ?& boiler ?& boiler ?& boiler ?& boiler ?
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Fresh waterFresh water
Copyright@Dominic Foo Pinch Analysis for Water Recovery 18
Stream segregation?Stream segregation?Stream segregation?Stream segregation?Stream segregation?Stream segregation?Stream segregation?Stream segregation?
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Fresh waterFresh water
Copyright@Dominic Foo Pinch Analysis for Water Recovery 19
Add a purification unit?Add a purification unit?Add a purification unit?Add a purification unit?Add a purification unit?Add a purification unit?Add a purification unit?Add a purification unit?
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Fresh waterFresh water
Separator
Copyright@Dominic Foo Pinch Analysis for Water Recovery 20
Defining separation technologiesDefining separation technologiesDefining separation technologiesDefining separation technologiesDefining separation technologiesDefining separation technologiesDefining separation technologiesDefining separation technologies
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Fresh waterFresh water
Ion Exchange Extraction
Copyright@Dominic Foo Pinch Analysis for Water Recovery 21
Or hybrid separation?Or hybrid separation?Or hybrid separation?Or hybrid separation?Or hybrid separation?Or hybrid separation?Or hybrid separation?Or hybrid separation?
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Fresh waterFresh water
Ion Exchange
Extraction
Copyright@Dominic Foo Pinch Analysis for Water Recovery 22
In different order?In different order?In different order?In different order?In different order?In different order?In different order?In different order?
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Fresh waterFresh water
Ion Exchange
Extraction
Copyright@Dominic Foo Pinch Analysis for Water Recovery 23
The problem statementsThe problem statementsThe problem statementsThe problem statementsThe problem statementsThe problem statementsThe problem statementsThe problem statements
� Is there any possibility of water reuse in this process?
� How to minimise the fresh water usage?
� How much wastewater flowrates can be reduced?
� Where to place a water purifier?
Is there an optimal solution???
Copyright@Dominic Foo Pinch Analysis for Water Recovery 24
Is there a quickIs there a quickIs there a quickIs there a quick----kill solution?kill solution?kill solution?kill solution?
Copyright@Dominic Foo Pinch Analysis for Water Recovery 25
Recent advances in pinch analysisRecent advances in pinch analysisRecent advances in pinch analysisRecent advances in pinch analysis
1970s Synthesis of heat exchanger network (HEN)
1994 Water minimisation (water pinch)
1989 Synthesis of mass exchange network (MEN)
2002 Property integration (property pinch)
2007 Energy planning (carbon pinch)
1987 Synthesis of HEN for batch processes
Graphical targeting Graphical targeting Graphical targeting Graphical targeting Graphical targeting Graphical targeting Graphical targeting Graphical targeting –––––––– Material Material Material Material Material Material Material Material
Recovery Pinch Diagram Recovery Pinch Diagram Recovery Pinch Diagram Recovery Pinch Diagram Recovery Pinch Diagram Recovery Pinch Diagram Recovery Pinch Diagram Recovery Pinch Diagram
(El-Halwagi et al., 2003; Prakash & Shenoy, 2005)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 27
Water reuse/recycleWater reuse/recycleWater reuse/recycleWater reuse/recycle
Process 1
Process 2
Process 1
Process 2
Regeneration
Process 1
Process 2
Regeneration
Reuse
Regeneration-reuse
Regeneration-recycling
(Wang & Smith, 1994, 1995)
Process 1
Recycle
Current focus
Copyright@Dominic Foo Pinch Analysis for Water Recovery 28
Graphical approach Graphical approach Graphical approach Graphical approach –––– Material Material Material Material recovery pinch diagram (MRPD)recovery pinch diagram (MRPD)recovery pinch diagram (MRPD)recovery pinch diagram (MRPD)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 29
Source: A stream which contains the targeted species. Each source has: �Flowrate Fi�Impurity concentration Ci
�Impurity load:mi = Fi Ci
Source: A stream which contains the targeted species. Each source has: �Flowrate Fi�Impurity concentration Ci
�Impurity load:mi = Fi Ci
Sink/source representationSink/source representationSink/source representationSink/source representationSink/source representationSink/source representationSink/source representationSink/source representation
Sink: An existing process unit/ equipment that can accept a source. Each sink has: �Flowrate Fj�Impurity concentration Cj
where: Cj
min≤ Cj≤ Cjmax
�Load capacity: mi = Fi Ci
Sink: An existing process unit/ equipment that can accept a source. Each sink has: �Flowrate Fj�Impurity concentration Cj
where: Cj
min≤ Cj≤ Cjmax
�Load capacity: mi = Fi Ci
Source iSegregated sources
j = 1
j = 2
Sinks j
?j = 3
i = 1
i = 2
i = 3
(El-Halwagi, 2006)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 30
Water sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN case
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam-jet Ejector
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s Water source ???
Copyright@Dominic Foo Pinch Analysis for Water Recovery 31
Water sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN caseWater sinks & sources for AN case
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam-jet Ejector
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Copyright@Dominic Foo Pinch Analysis for Water Recovery 32
TechnicalTechnicalTechnicalTechnicalTechnicalTechnicalTechnicalTechnical constraints constraints constraints constraints constraints constraints constraints constraints i. Scrubber
� 5.8 ≤ flowrate of wash feed (kg/s) ≤ 6.2
� 0.0 ≤ NH3 content of wash feed (ppm) ≤ 10.0
ii. Boiler feed water � NH3 content = 0.0 ppm
� AN content = 0.0 ppm
iii. Decanter� 10.6 ≤ feed flowrate (kg/s) ≤ 11.1
iv. Distillation column� 5.2 ≤ feed flowrate (kg/s) ≤ 5.7
� 0.0 ≤ NH3 content of feed (ppm) ≤ 30.0
� 80.0 ≤ AN content of feed (wt%) ≤ 100.0
Upper bound
Lower bound
Upper bound
Lower bound
Copyright@Dominic Foo Pinch Analysis for Water Recovery 33
Limiting water data for AN caseLimiting water data for AN caseLimiting water data for AN caseLimiting water data for AN caseLimiting water data for AN caseLimiting water data for AN caseLimiting water data for AN caseLimiting water data for AN case
Water sinks, SKj Flowrate Concentration
j Stream Fj (kg/s) Cj (ppm)
1 Boiler feed water (BFW) 1.2 0
2 Scrubber 5.8 10
Water sources, SRi Flowrate Concentration
i Stream Fi (kg/s) Ci (ppm)
1 Distillation bottoms 0.8 0
2 Off-gas condensate 5.0 14
3 Aqueous layer 5.9 25
4 Ejector condensate 1.4 34
Copyright@Dominic Foo Pinch Analysis for Water Recovery 34
Material recovery pinch diagramMaterial recovery pinch diagramMaterial recovery pinch diagramMaterial recovery pinch diagramMaterial recovery pinch diagramMaterial recovery pinch diagramMaterial recovery pinch diagramMaterial recovery pinch diagram
� Fulfil the following constraints:� Material flowrate
� Impurity load
� Not limited to water network, other applications include gas & property network.
� Steps required:� Arrange water sinks & sources according to their respective
concentration level in ascending order
� Plot flowrate vs. limiting mass load for all water sinks to form sink composite curve
� Plot flowrate vs. limiting mass load for all water sources to form source composite curve
� Shift source composite to the right & below sink composite
Copyright@Dominic Foo Pinch Analysis for Water Recovery 35
Sink composite curveSink composite curveSink composite curveSink composite curveSink composite curveSink composite curveSink composite curveSink composite curve
Sink, SKj Fj (kg/s) Cj (ppm) mj (mg/s)
SK1 1.2 0 0
SK2 5.8 10 58
ΣΣΣΣj 7.0 58
Lim
itin
g m
ass
lo
ad
(m
g/s
)
Flowrate (kg/s)5 10 15
50
100
150
200
250
300
SK1
SK2
Copyright@Dominic Foo Pinch Analysis for Water Recovery 36
Source composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource Fi (kg/s) Ci (ppm) mi (mg/s)
SR1 0.8 0 0
SR2 5.0 14 70.0
SR3 5.9 25 147.5
SR4 1.4 34 47.6
ΣΣΣΣi 13.1 265.1
Lim
itin
g m
ass
lo
ad
(m
g/s
)
Flowrate (kg/s)5 10 15
50
100
150
200
250
300
SR1
SR2
SR3
SR4
Copyright@Dominic Foo Pinch Analysis for Water Recovery 37
Source composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource composite curveSource Fi (kg/s) Ci (ppm) mi (mg/s)
SR1 0.8 0 0
SR2 5.0 14 70.0
SR3 5.9 25 147.5
SR4 1.4 34 47.6
ΣΣΣΣi 13.1 265.1
Lim
itin
g m
ass
lo
ad
(m
g/s
)
Flowrate (kg/s)5 10 15
50
100
150
200
250
300
FFW = 2.1FWW = 8.2
Copyright@Dominic Foo Pinch Analysis for Water Recovery 38
Pure vs. impure fresh sourcePure vs. impure fresh sourcePure vs. impure fresh sourcePure vs. impure fresh sourcePure vs. impure fresh sourcePure vs. impure fresh sourcePure vs. impure fresh sourcePure vs. impure fresh source
Impurity load
Flowrate
Minimum
waste
Maximum
recycle
Pinch
point
Sink
composite
Source
composite
Minimum
fresh
Impurity load
Flowrate
Minimum
waste
Maximum
recycle
Pinch
point
Sink
composite
Source
composite
Minimum
fresh
Impure fresh
locus
Copyright@Dominic Foo Pinch Analysis for Water Recovery 39
Less & over integrationLess & over integrationLess & over integrationLess & over integrationLess & over integrationLess & over integrationLess & over integrationLess & over integration
Impurity load
Flowrate
Minimum
waste
Recycle
Pinch
point
Sink
composite
Source
composite
Minimum
fresh
αααα
αααααααα
Impurity load
Flowrate
WasteRecycle
Infeasible
region
Sink
composite
Source
composite
Fresh
(El-Halwagi, 2006)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 40Copyright@Dominic Foo H84PSD - Process Synthesis & Design Lecture 3 - 40
Significant of the pinch pointSignificant of the pinch pointSignificant of the pinch pointSignificant of the pinch pointSignificant of the pinch pointSignificant of the pinch pointSignificant of the pinch pointSignificant of the pinch point
� The pinch point always located at the pinch causing source
� Some golden rules
�Fresh resource can only be used in lower conc. region
�Sources above the pinch (including fresh feed) should not be fed to sink below the pinch, & may not also mix with sources that are below the pinch concentration.
� The pinch causing source is an exception, as part of it belongs to the region below the pinch.
(Hallale 2002; Manan et al., 2004)
Network design technique Network design technique Network design technique Network design technique ––––
Nearest Nearest Nearest Nearest NeighbourNeighbourNeighbourNeighbour Algorithm (NNA)Algorithm (NNA)Algorithm (NNA)Algorithm (NNA)
(Prakash & Shenoy, 2005a)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 42
Basic principleBasic principleBasic principleBasic principle
� To satisfy a sink, the source to be chosen are the nearest available neighbors to the sink in terms of impurity concentration.
� A source that is just cleaner and a source that is just dirtier than the sink are mixed to satisfy the sink.
SR1
SK150 ppm
SR3SR2
0 ppm 80 ppm 100 ppm
SR1
SK150 ppm
SR3SR2
0 ppm 20 ppm 100 ppm
Copyright@Dominic Foo Pinch Analysis for Water Recovery 43
Basic principleBasic principleBasic principleBasic principle
� If the required amount of a source is not available, then whatever is available of that source is used completely and the next neighbor source is considered to satisfy the sink.
SR1
SK1150 t/h50 ppm
SR3SR2
100 ton/h
0 ppm
1 ton/h
80 ppm
20 ton/h
100 ppm
Copyright@Dominic Foo Pinch Analysis for Water Recovery 44
Important equationsImportant equationsImportant equationsImportant equations
� Assign a pair of neighbours (sources) for the sink:
�Neighbour 1 (N1) – lower C than the sink
�Neighbour 2 (N2) – higher C than the sink
� Solve the flowrate allocation from source i (i.e. i = N1 & N2) to sink j:
�Overall material balance:
� Impurity balance:
jjj FFF SKSK N2,SK N1, =+
jjjj CFCFCF SKSKN2SK N2,1NSK N1, =+
Copyright@Dominic Foo Pinch Analysis for Water Recovery 45
Main steps for NNAMain steps for NNAMain steps for NNAMain steps for NNA1. Arrange sinks/sources in increasing order of C, and start
from sink with lowest Cj.2. Identify source with the same conc. as the sink, i.e. Ci = Cj �
to Step 3; else to Step 4.3. Feed source to the sink when Ci = Cj:
a) If Fi ≥ Fj , source is sufficient to satisfy the sink; to Step 2 for the next sink
b) If Fi ≤ Fj , feed the whole source to the sink, to Step 4
4. Identify the pair of neighbours for the sink; determine the flowrate using Eqs. (1) and (2).
5. Feed source to the sink:a) If Fi,j ≤ the available Fi, the entire sink requirement is met � to Step 2
for next sink.b) If Fi,j ≥ the available Fi, use the entire source & solve for next pair of
neighbours.
6. Repeat Steps 2 – 5 for all sinks.
Copyright@Dominic Foo Pinch Analysis for Water Recovery 46
Example (Example (Example (Example (PolleyPolleyPolleyPolley & & & & PolleyPolleyPolleyPolley, 2000) , 2000) , 2000) , 2000)
20070SK4
10080SK3
50100SK2
2050SK1
15070SR3
100100SR2
25060SR4
5050SR1
Concentration, C (ppm)
Water flowrate, Fi (t/h)
Sources, SRi
Concentration, C (ppm)
Water flowrate, Fj (t/h)
Sinks, SKj
(Answer: FFW = 70 t/h; FWW = 50 t/h; Cpinch = 150 ppm)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 47
Network design with NNANetwork design with NNANetwork design with NNANetwork design with NNA
SK1F = 50 t/hC = 20 ppmm = 1000
SK2F = 100 t/hC = 50 ppmm = 5000
SK3F = 80 t/hC = 100 ppmm = 8000
SR1
SR2
SR3
SR4
20 t/h 65 t/h 35 t/h
25 t/h
30 t/h 35 t/h
SK4F = 70 t/hC = 200 ppmm = 14000
35 t/h
F = 50 t/h
C = 50 ppm
F = 100 t/h
C = 100 ppm
F = 70 t/h
C = 150 ppm
F = 60 t/h
C = 250 ppm
10 t/h
5 t/h
FW
25 t/h
35 t/h30 t/h
F = 70 t/h
C = 0 ppm
Copyright@Dominic Foo Pinch Analysis for Water Recovery 48
Sink/source matching matrixSink/source matching matrixSink/source matching matrixSink/source matching matrix
SR425060
SR315070
SR2100100
SR15050
FW070
WWSK4SK3SK2SK1SK
j
SRi
Ci(ppm)F
i(t/h)
2001005020Cj(ppm)
50708010050Fj(t/h)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 49
Back to AN case againBack to AN case againBack to AN case againBack to AN case againBack to AN case againBack to AN case againBack to AN case againBack to AN case again
Water sinks, SKj Flowrate Concentration
j Stream Fj (kg/s) Cj (ppm)
1 Boiler feed water (BFW) 1.2 0
2 Scrubber 5.8 10
Water sources, SRi Flowrate Concentration
i Stream Fi (kg/s) Ci (ppm)
1 Distillation bottoms 0.8 0
2 Off-gas condensate 5.0 14
3 Aqueous layer 5.9 25
4 Ejector condensate 1.4 34
Copyright@Dominic Foo Pinch Analysis for Water Recovery 50
Network design with NNANetwork design with NNANetwork design with NNANetwork design with NNA
SK1F = 1.2 kg/sC = 0m = 0
SK2F = 5.8 kg/sC = 10m = 58
SR1
SR2
SR3
SR4
F = 0.8 kg/s
C = 0 ppm
F = 5.0 kg/s
C = 14 ppm
F = 5.9 kg/s
C = 25 ppm
F = 1.4 kg/s
C = 34 ppm
FWF = 2.1 kg/s
C = 0 ppm1.7 kg/s0.4 kg/s
4.1 kg/s
8.2 kg/s
Copyright@Dominic Foo Pinch Analysis for Water Recovery 51
Alternative designAlternative designAlternative designAlternative design
SK1F = 1.2 kg/sC = 0m = 0
SK2F = 5.8 kg/sC = 10m = 58
SR1
SR2
SR3
SR4
F = 0.8 kg/s
C = 0 ppm
F = 5.0 kg/s
C = 14 ppm
F = 5.9 kg/s
C = 25 ppm
F = 1.4 kg/s
C = 34 ppm
FWF = 2.1 kg/s
C = 0 ppm0.9 kg/s1.2 kg/s
4.1 kg/s
8.2 kg/s
Copyright@Dominic Foo Pinch Analysis for Water Recovery 52
Network design for reuse/recycleNetwork design for reuse/recycleNetwork design for reuse/recycleNetwork design for reuse/recycle
Reactor
Decanter
Distillation
Column
O2
Aqueous
layer
ScrubberNH3
C3H6
Steam
Wastewater to Biotreatment
Off-Gas
Condensate
Condensate
Bottoms
Water
AN to sales
6.0 kg H2O/s5.0 kg AN/s
5.1 kg H2O/s
+ Gases Tail gases
to disposal
Boiler
BFW
1.2 kg H2O/s
14 ppm NH3
0.4 kg AN/s
4.6 kg H2O/s
18 ppm NH3
4.6 kg AN/s
6.5 kg H2O/s
10 ppm NH3
4.2 kg AN/s
1.0 kg H2O/s
25 ppm NH3
0.4 kg AN/s
5.5 kg H2O/s
0 ppm NH3
0.1 kg AN/s
0.7 kg H2O/s
1 ppm NH3
3.9 kg AN/s
0.3 kg H2O/s
34 ppm NH3
0.2 kg AN/s
1.2 kg H2O/s
20 ppm NH3
1.1 kg AN/s
12.0 kg H2O/s
Fresh waterFresh water
Network evolution techniquesNetwork evolution techniquesNetwork evolution techniquesNetwork evolution techniques
(Prakash & Shenoy, 2005b; Ng & Foo, 2006)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 54
Source Shift Algorithm (SSA)Source Shift Algorithm (SSA)Source Shift Algorithm (SSA)Source Shift Algorithm (SSA)
� Objective: To simplify a preliminary networkdesigned by NNA
� 2 main criteria to consider sink-source candidates:
�CSK = CSR
�FSK ≤ FSR
� Main steps:
� Identify the sink-source pairs that fulfil both criteria
�Feed the sink fully with the source
�An equal flowrate of source(s) will be shifted to the sink that was originally fed by the source
Copyright@Dominic Foo Pinch Analysis for Water Recovery 55
SK1F = 100 t/hC = 100 ppm
SK2F = 100 t/hC = 100 ppm
FWF = 50 t/hC = 0 ppm
SR1F = 100 t/hC = 100 ppm
SR2F = 50 t/h
C = 200 ppm
25 25
25 25
50 50(50)
(25)
(25)
(a) (b)
SK2F = 100 t/hC = 100 ppm
SK1F = 100 t/hC = 100 ppm
FWF = 50 t/hC = 0 ppm
SR1F = 100 t/hC = 100 ppm
SR2F = 50 t/h
C = 200 ppm
100
50
50
A simple exampleA simple exampleA simple exampleA simple example
Copyright@Dominic Foo Pinch Analysis for Water Recovery 56
Another configurationAnother configurationAnother configurationAnother configuration
SK1F = 100 t/hC = 100 ppm
SK2F = 100 t/hC = 100 ppm
FWF = 50 t/hC = 0 ppm
SR1F = 100 t/hC = 100 ppm
SR2F = 50 t/h
C = 200 ppm
25 25
25 25
50 50(50)
(25)
(25)
(a) (b)
SK2F = 100 t/hC = 100 ppm
SK1F = 100 t/hC = 100 ppm
FWF = 50 t/hC = 0 ppm
SR1F = 100 t/hC = 100 ppm
SR2F = 50 t/h
C = 200 ppm
100
50
50
Copyright@Dominic Foo Pinch Analysis for Water Recovery 57
Example (Example (Example (Example (PolleyPolleyPolleyPolley & & & & PolleyPolleyPolleyPolley, 2000) , 2000) , 2000) , 2000)
20070SK4
10080SK3
50100SK2
2050SK1
15070SR3
100100SR2
25060SR4
5050SR1
Concentration, C (ppm)
Water flowrate, Fi (t/h)
Sources, SRi
Concentration, C (ppm)
Water flowrate, Fj (t/h)
Sinks, SKj
(Answer: FFW = 70 t/h; FWW = 50 t/h; Cpinch = 150 ppm)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 58
Identifying sinkIdentifying sinkIdentifying sinkIdentifying sink----source pairssource pairssource pairssource pairs
2535SR425060
253510SR315070
6535SR2100100
3020SR15050
53530FW070
WWSK4SK3SK2SK1SK
j
SRi
Ci(ppm)F
i(t/h)
2001005020Cj(ppm)
50708010050Fj(t/h)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 59
Interconnections: 12 Interconnections: 12 Interconnections: 12 Interconnections: 12 ���� 11 11 11 11 ���� 10101010
2535SR425060
253510SR315070
6535SR2100100
3020SR15050
53530FW070
WWSK4SK3SK2SK1SK
j
SRi
Ci(ppm)F
i(t/h)
2001005020Cj(ppm)
50708010050Fj(t/h)
5
15
10
80
40
10
20
25
2560
5010
Copyright@Dominic Foo Pinch Analysis for Water Recovery 60
Water Path Analysis (WPA)Water Path Analysis (WPA)Water Path Analysis (WPA)Water Path Analysis (WPA)
� Definition: a continuous route which starts from a fresh source, linked with the sink-source connections, and end at a waste sink.
� Objective: Generate alternative networks by adding fresh resource penalties.
� Analogy:� Utility path in removing the smallest heat exchanger unit in HEN
(Linnhoff et al., 1982; Smith, 1995, 2005).
� Mass-load path to reduce number of mass exchangers in MEN (El-Halwagi, 1997).
� Heuristic: to minimise water penalty, remove the smallest match among all L-kink connections within all available water paths.
Copyright@Dominic Foo Pinch Analysis for Water Recovery 61
Identifying water pathsIdentifying water pathsIdentifying water pathsIdentifying water paths
5010SR425060
6010SR315070
8020SR2100100
3020SR15050
4030FW070
WWSK4SK3SK2SK1SK
j
SRi
Ci(ppm)F
i(t/h)
2001005020Cj(ppm)
50708010050Fj(t/h)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 62
Remove 2 matches with 10 t/h FWRemove 2 matches with 10 t/h FWRemove 2 matches with 10 t/h FWRemove 2 matches with 10 t/h FW
5010SR425060
6010SR315070
8020SR2100100
3020SR15050
4030FW070
WWSK4SK3SK2SK1SK
j
SRi
Ci(ppm)F
i(t/h)
2001005020Cj(ppm)
50708010050Fj(t/h)
50
60
7010
10
Copyright@Dominic Foo Pinch Analysis for Water Recovery 63
Remove 3 matches with 30 t/h FWRemove 3 matches with 30 t/h FWRemove 3 matches with 30 t/h FWRemove 3 matches with 30 t/h FW
60SR425060
70SR315070
8020SR2100100
3020SR15050
5030FW070
WWSK4SK3SK2SK1SK
j
SRi
Ci(ppm)F
i(t/h)
2001005020Cj(ppm)
50708010050Fj(t/h)
20
50
5020
20
Algebraic approach Algebraic approach Algebraic approach Algebraic approach Algebraic approach Algebraic approach Algebraic approach Algebraic approach ––––––––
Water Cascade Analysis Water Cascade Analysis Water Cascade Analysis Water Cascade Analysis Water Cascade Analysis Water Cascade Analysis Water Cascade Analysis Water Cascade Analysis
(Manan et al., 2004; Foo et al., 2006)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 65
Graphical vs. algebraic approachesGraphical vs. algebraic approachesGraphical vs. algebraic approachesGraphical vs. algebraic approachesGraphical vs. algebraic approachesGraphical vs. algebraic approachesGraphical vs. algebraic approachesGraphical vs. algebraic approaches
Graphical approachGraphical approach
� Advantages� Good insights of the
problems
� Intuitive
� Limitations� Tedious solution for
complex problem
� Inaccuracy problems
� Scaling problems/ dimensionality
Algebraic ApproachAlgebraic Approach
� Advantages
� Computational effectiveness
� Ease for large & complex problems
� Interaction with other softwares, e.g. process simulators, spreadsheets
� Limitations� Less insight on the problem
Copyright@Dominic Foo Pinch Analysis for Water Recovery 66
Concept of material cascadingConcept of material cascadingConcept of material cascadingConcept of material cascadingConcept of material cascadingConcept of material cascadingConcept of material cascadingConcept of material cascading
100 ppm
100 kg/s
200 ppm
–50 kg/s
100 kg/s
(waste)
100 kg/s
(fresh source)
100 ppm
100 kg/s
200 ppm
–50 kg/s
100 kg/s
50 kg/s(waste)
Without reuse Reuse
Copyright@Dominic Foo Pinch Analysis for Water Recovery 67
General formGeneral formGeneral formGeneral formGeneral formGeneral formGeneral formGeneral form
k Ck ΣΣΣΣj Fj ΣΣΣΣi Fi ΣΣΣΣi Fi −−−− ΣΣΣΣj Fj F
C, k ∆∆∆∆m kCum. ∆∆∆∆mk
FF
k Ck (Σ
jFj)1
(ΣiFi)1
(ΣiFi− Σ
jFj)1
FC, k ∆m
k
k + 1 Ck+1 (Σ
jFj)k+1
(ΣiFi)k+1
(ΣiFi− Σ
jFj)k+1
Cum. ∆mk+1
FFW, k+1
FC, k+1 ∆m
k+1
……
…
……
…
……
…
……
…
……
…
……
…
……
…
……
…
……
…
n – 2 Cn–2 (Σ
jFj)n-2
(ΣiFi)n-2
(ΣiFi− Σ
jFj)n-2
FC, n–2 ∆m
n–2
n – 1 Cn–1 (Σ
jFj)n-1
(ΣiFi)n-1
(ΣiFi− Σ
jFj)n-1
Cum. ∆mn–1
FFW, n–1
FC, n–1
= FW ∆m
n–1
n Cn Cum. ∆m
nFFW, n
FW
FW,
Cum.
CC
mF
k
kk
−
∆=
Copyright@Dominic Foo Pinch Analysis for Water Recovery 68
Example of WCA Example of WCA Example of WCA Example of WCA Example of WCA Example of WCA Example of WCA Example of WCA –––––––– AN productionAN productionAN productionAN productionAN productionAN productionAN productionAN production
Water sinks, SKj Flowrate Concentration
j Stream Fj (kg/s) Cj (ppm)
1 Boiler feed water (BFW) 1.2 0
2 Scrubber 5.8 10
Water sources, SRi Flowrate Concentration
i Stream Fi (kg/s) Ci (ppm)
1 Distillation bottoms 0.8 0
2 Off-gas condensate 5.0 14
3 Aqueous layer 5.9 25
4 Ejector condensate 1.4 34
Copyright@Dominic Foo Pinch Analysis for Water Recovery 69
Infeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascade
kCk
(ppm)ΣΣΣΣj Fj
(kg/s)ΣΣΣΣi Fi
(kg/s)ΣΣΣΣi Fi - ΣΣΣΣj Fj
(kg/s)FC
(kg/s)∆∆∆∆m
(mg/s)Cum. ∆∆∆∆m
(mg/s)(kg/s)
1 0 1.2 0.8 -0.4
-0.4 -4
2 10 5.8 -5.8 -4 -0.40
-6.2 -24.8
3 14 5 5 -28.8 -2.06
-1.2 -13.2
4 25 5.9 5.9 -42 -1.68
4.7 42.3
5 34 1.4 1.4 0.3 0.01
6.1 6099792.6
6 1000000 6099792.9 6.10
FW
FW,
Cum.
CC
mF
k
kk
−
∆=
Copyright@Dominic Foo Pinch Analysis for Water Recovery 70
Feasible cascade Feasible cascade Feasible cascade Feasible cascade Feasible cascade Feasible cascade Feasible cascade Feasible cascade
kCk
(ppm)ΣΣΣΣj Fj
(kg/s)ΣΣΣΣi Fi
(kg/s)ΣΣΣΣi Fi - ΣΣΣΣj Fj
(kg/s)FC
(kg/s)∆∆∆∆m
(mg/s)Cum. ∆∆∆∆m
(mg/s)
FFW = 2.06
1 0 1.2 0.8 -0.4
1.66 16.57
2 10 5.8 -5.8 16.57
-4.14 -16.57
3 14 5 5 0.00
0.86 9.43 (PINCH)
4 25 5.9 5.9 9.43
6.76 60.81
5 34 1.4 1.4 70.24
FWW = 8.16 8156865.51
6 1000000 8156935.76
Copyright@Dominic Foo Pinch Analysis for Water Recovery 71
Water allocation targetsWater allocation targetsWater allocation targetsWater allocation targetsWater allocation targetsWater allocation targetsWater allocation targetsWater allocation targets
kCk
(ppm)ΣΣΣΣj Fj
(kg/s)ΣΣΣΣi Fi
(kg/s)ΣΣΣΣi Fi - ΣΣΣΣj Fj
(kg/s)FC
(kg/s)∆∆∆∆m
(mg/s)Cum. ∆∆∆∆m
(mg/s)
FFW = 2.06
1 0 1.2 0.8 -0.4
1.66 16.57
2 10 5.8 -5.8 16.57
-4.14 -16.57
3 14 5 5 0.00
0.86 9.43 (PINCH)
4 25 5.9 5.9 9.43
6.76 60.81
5 34 1.4 1.4 70.24
FWW = 8.16 8156865.51
6 1000000 8156935.76
Pinch causing source
(Manan et al., 2004)
Lower conc.
region
Higher conc.
region
Copyright@Dominic Foo Pinch Analysis for Water Recovery 72
Example (Example (Example (Example (PolleyPolleyPolleyPolley & & & & PolleyPolleyPolleyPolley, 2000) , 2000) , 2000) , 2000)
20070SK4
10080SK3
50100SK2
2050SK1
15070SR3
100100SR2
25060SR4
5050SR1
Concentration, C (ppm)
Water flowrate, Fi (t/h)
Sources, SRi
Concentration, C (ppm)
Water flowrate, Fj (t/h)
Sinks, SKj
(Answer: FFW = 70 t/h; FWW = 50 t/h; Cpinch = 150 ppm)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 73
Infeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascadeInfeasible cascade
4
5
k Ck ΣΣΣΣj Fj ΣΣΣΣi Fi ΣΣΣΣi Fi - ΣΣΣΣj Fj FC ∆∆∆∆m Cum. ∆∆∆∆m
01 20
2
3
6
7 106
F
F,
Cum.
CC
mF
k
kk
−
∆=
Copyright@Dominic Foo Pinch Analysis for Water Recovery 74
Feasible cascadeFeasible cascadeFeasible cascadeFeasible cascadeFeasible cascadeFeasible cascadeFeasible cascadeFeasible cascade
4
5
k Ck ΣΣΣΣj Fj ΣΣΣΣi Fi ΣΣΣΣi Fi - ΣΣΣΣj Fj FC ∆∆∆∆m Cum. ∆∆∆∆m
FFW = _______1 20
2
3
6FWW = _______
7 106
Targeting for water regenerationTargeting for water regenerationTargeting for water regenerationTargeting for water regeneration
(Ng et al., 2007, 2008)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 76
Water regenerationWater regenerationWater regenerationWater regenerationWater regenerationWater regenerationWater regenerationWater regeneration
Process 1
Process 2
Process 1
Process 2
Regeneration
Process 1
Process 2
Regeneration
Reuse
Regeneration-reuse
Regeneration-recycling
(Wang & Smith, 1994, 1995)
Process 1
RecycleCurrent focus
Copyright@Dominic Foo Pinch Analysis for Water Recovery 77
Process 1
Process 3 Process 4
Process 2
FW WW
Reuse
Recycle
FW : fresh water WW : wastewater
Reuse
Water reuse/recycle schemeWater reuse/recycle schemeWater reuse/recycle schemeWater reuse/recycle schemeWater reuse/recycle schemeWater reuse/recycle schemeWater reuse/recycle schemeWater reuse/recycle scheme
Copyright@Dominic Foo Pinch Analysis for Water Recovery 78
Regeneration processes(concentration/pressure driven)
Mass separating agents Power/pressure
FW : fresh water WW : wastewater RW : regenerated water
Water reuse/recycle + regenerationWater reuse/recycle + regenerationWater reuse/recycle + regenerationWater reuse/recycle + regenerationWater reuse/recycle + regenerationWater reuse/recycle + regenerationWater reuse/recycle + regenerationWater reuse/recycle + regeneration
Process 1
Process 3 Process 4
Process 2
FW
WW
RW
Copyright@Dominic Foo Pinch Analysis for Water Recovery 79
Example (Example (Example (Example (Example (Example (Example (Example (PolleyPolleyPolleyPolleyPolleyPolleyPolleyPolley & & & & & & & & PolleyPolleyPolleyPolleyPolleyPolleyPolleyPolley, 2000) , 2000) , 2000) , 2000) , 2000) , 2000) , 2000) , 2000)
Sinks, SKj
Water flowrate, Fj (t/h)
Concentration, C (ppm)
SK1 50 20
SK2 100 50
SK3 80 100
SK4 70 200
Sources,
SRi
Water flowrate, Fi (t/h)
Concentration, C (ppm)
SR1 50 50
SR2 100 100
SR3 70 150
SR4 60 250
(Answer: FFW = 70 t/h; FWW = 50 t/h; Cpinch = 150 ppm)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 80
AlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithm
Assumptions:
1. Fixed regen outlet concentration (Cout)
2. Cost of regeneration is omitted
Source(s) is shifted to the FWR from highest
Cj until ΣjFj= ΣiFi in the RWR
Set regeneration concentration, Cout
Preliminary allocation – water sinks/sources are separated
into FWR (Ci ,Cj < Cout) and RWR (Ci ,Cj > Cout)
RWR
ΣjFj> ΣiFi
NO
YES
Sink(s) is shifted to the FWR from lowest Cj until
ΣjFj= ΣiFi in the RWR
Additional sink (Fj, A) and source flowrate (Fi, A) are
shifted to the FWR, calculated based on:
Fj Cj = Fi, A (Ci, A – Cj, A)
Ultimate flowrate targets
START
All SKj in the FWR with
Cj= 0 ppm?
YES
NO
END
Determine FFW and FWW in FWR
Total FRW = FRW, FWR + FRW, RWR
FRW, FWR is added at Cout in FWR
Calculate FRW, FWR = ((Fj× Cj)/ CF)
ΣiFi (with Ci higher than
Cout) ≤ FRW, FWR
Note: FWR – fresh water regionRWR – regenerated water region
Copyright@Dominic Foo Pinch Analysis for Water Recovery 81
Preliminary allocation (Preliminary allocation (Preliminary allocation (Preliminary allocation (Preliminary allocation (Preliminary allocation (Preliminary allocation (Preliminary allocation (CCCCCCCCoutoutoutoutoutoutoutout = 10 ppm)= 10 ppm)= 10 ppm)= 10 ppm)= 10 ppm)= 10 ppm)= 10 ppm)= 10 ppm)
k C ΣjFj
Σi Fi
Σi Fi− Σ
i Fj
FC ∆m
kCum ∆m
k
FFW = 70.00
1 0 0 70 1.41.4
2 20 50 -50 20 0.62
3 50 100 50 -50 -30 -1.50.5
4 100 80 100 20 -10 -0.50
5 150 70 70 60 3 (PINCH)3
6 200 70 -70 -10 -0.52.5
7 250 60 60 FWW= 50.00 49987.549990
11 106 0
Total 300 280
Cout = 10 ppm
No FW is used here
May use both FW or RW
Copyright@Dominic Foo Pinch Analysis for Water Recovery 82
AlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithm
Source(s) is shifted to the FWR from highest
Cj until ΣjFj= ΣiFi in the RWR
Set regeneration concentration, Cout
Preliminary allocation – water sinks/sources are separated
into FWR (Ci ,Cj < Cout) and RWR (Ci ,Cj > Cout)
RWR
ΣjFj> ΣiFi
NO
YES
Sink(s) is shifted to the FWR from lowest Cj until
ΣΣΣΣjFj= ΣΣΣΣiFi in the RWR
Additional sink (Fj, A) and source flowrate (Fi, A)
are shifted to the FWR, calculated based on:
Fj Cj = Fi, A (Ci, A – Cj, A)
Ultimate flowrate targets
START
All SKj in the FWR with
Cj= 0 ppm?
YES
NO
END
Determine FFW and FWW in FWR
Total FRW = FRW, FWR + FRW, RWR
FRW, FWR is added at Cout in FWR
Calculate FRW, FWR = ((Fj× Cj)/ CF)
ΣiFi (with Ci higher than
Cout) ≤ FRW, FWR
Copyright@Dominic Foo Pinch Analysis for Water Recovery 83
Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of sink(ssink(ssink(ssink(ssink(ssink(ssink(ssink(s) & ) & ) & ) & ) & ) & ) & ) & source(ssource(ssource(ssource(ssource(ssource(ssource(ssource(s))))))))FWR RWR
C ΣjFj Σi Fi C ΣjFj Σi Fi0 Cout= 10
20 20 20 30
50 50 100 50
100 100 80 100
150 150 70
200 200 70
250 250 60
106 106
Total 20 Total 280 280
Why should we use FW this source can tolerate dirty water? Can we maximise its load?
Copyright@Dominic Foo Pinch Analysis for Water Recovery 84
AlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithm
Source(s) is shifted to the FWR from highest
Cj until ΣjFj= ΣiFi in the RWR
Set regeneration concentration, Cout
Preliminary allocation – water sinks/sources are separated
into FWR (Ci ,Cj < Cout) and RWR (Ci ,Cj > Cout)
RWR
ΣjFj> ΣiFi
NO
YES
Sink(s) is shifted to the FWR from lowest Cj until
ΣΣΣΣjFj= ΣΣΣΣiFi in the RWR
Additional sink (Fj, A) and source flowrate (Fi, A)
are shifted to the FWR, calculated based on:
Fj Cj = Fi, A (Ci, A – Cj, A)
Ultimate flowrate targets
START
All SKj in the FWR with
Cj= 0 ppm?
YES
NO
END
Determine FFW and FWW in FWR
Total FRW = FRW, FWR + FRW, RWR
FRW, FWR is added at Cout in FWR
Calculate FRW, FWR = ((Fj× Cj)/ CF)
ΣiFi (with Ci higher than
Cout) ≤ FRW, FWR
Sink of the lowest Cj
Sources of the lowest Ci & positive value in the ΣiFi –ΣjFj column of WCT
Copyright@Dominic Foo Pinch Analysis for Water Recovery 85
Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of Reallocation of sink(ssink(ssink(ssink(ssink(ssink(ssink(ssink(s) & ) & ) & ) & ) & ) & ) & ) & source(ssource(ssource(ssource(ssource(ssource(ssource(ssource(s))))))))FWR RWR
C ΣjFj Σi Fi C ΣjFj Σi Fi0 Cout= 10
20 20 + 5 20 30 – 5
50 50 100 50
100 + 5 100 80 100 – 5
150 150 70
200 200 70
250 250 60
106 106
Total 20 + 5 5 Total 275 275
Copyright@Dominic Foo Pinch Analysis for Water Recovery 86
AlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithmAlgorithm
Source(s) is shifted to the FWR from highest
Cj until ΣjFj= ΣiFi in the RWR
Set regeneration concentration, Cout
Preliminary allocation – water sinks/sources are separated
into FWR (Ci ,Cj < Cout) and RWR (Ci ,Cj > Cout)
RWR
ΣjFj> ΣiFi
NO
YES
Sink(s) is shifted to the FWR from lowest Cj until
ΣjFj= ΣiFi in the RWR
Additional sink (Fj, A) and source flowrate (Fi, A) are
shifted to the FWR, calculated based on:
Fj Cj = Fi, A (Ci, A – Cj, A)
Ultimate flowrate targets
START
All SKj in the FWR with
Cj= 0 ppm?
YES
NO
END
Determine FFW and FWW in FWR
Total FRW = FRW, FWR + FRW, RWR
FRW, FWR is added at Cout in FWR
Calculate FRW, FWR = ((Fj× Cj)/ CF)
ΣiFi (with Ci higher than
Cout) ≤ FRW, FWR
Copyright@Dominic Foo Pinch Analysis for Water Recovery 87
FW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWR
kCk
(ppm)ΣΣΣΣj Fj(t/h)
ΣΣΣΣi Fi(t/h)
ΣΣΣΣi Fi - ΣΣΣΣj Fj(t/h)
FC
(t/h)∆∆∆∆m
(kg/h)Cum. ∆∆∆∆m
(kg/h)(t/h)
FFW =____
1 0
2 20 25 -25
3 50
4 100 5 5
FWW=____
5 106
Total 25 5
FW
FW,
Cum.
CC
mF
k
kk
−
∆=
Copyright@Dominic Foo Pinch Analysis for Water Recovery 88
FW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWRFW & WW targeting in FWR
kCk
(ppm)ΣΣΣΣj Fj(t/h)
ΣΣΣΣi Fi(t/h)
ΣΣΣΣi Fi - ΣΣΣΣj Fj(t/h)
FC
(t/h)∆∆∆∆m
(kg/h)Cum. ∆∆∆∆m
(kg/h)
FFW =______
1 0
0.40
2 20 25 -25 0.40
-0.15
3 50 0.25
-0.25
4 100 5 5 0.00
0.00
5 106 FWW =_____ 0.00
Total 25 5
Copyright@Dominic Foo Pinch Analysis for Water Recovery 89
RW
FW,
Cum.
CC
mF
k
kk
−
∆=k
Ck(ppm)
ΣΣΣΣj Fj(t/h)
ΣΣΣΣi Fi(t/h)
ΣΣΣΣi Fi - ΣΣΣΣj Fj(t/h)
FC
(t/h)∆∆∆∆m
(kg/h)Cum. ∆∆∆∆m
(kg/h) (t/h)
1 Cout= 10 FRW = ____
2 20 25 -25
3 50 100 50 -50
4 100 80 95 15
5 150 70 70
6 200 70 -70
7 250 60 60
FRW = ____8 106
Total 275 275
RW targeting in RWR (infeasible)RW targeting in RWR (infeasible)RW targeting in RWR (infeasible)RW targeting in RWR (infeasible)RW targeting in RWR (infeasible)RW targeting in RWR (infeasible)RW targeting in RWR (infeasible)RW targeting in RWR (infeasible)
Copyright@Dominic Foo Pinch Analysis for Water Recovery 90
RW targeting in RWR (feasible)RW targeting in RWR (feasible)RW targeting in RWR (feasible)RW targeting in RWR (feasible)RW targeting in RWR (feasible)RW targeting in RWR (feasible)RW targeting in RWR (feasible)RW targeting in RWR (feasible)
kCk
(ppm)ΣΣΣΣj Fj(t/h)
ΣΣΣΣi Fi(t/h)
ΣΣΣΣi Fi - ΣΣΣΣj Fj(t/h)
FC
(t/h)∆∆∆∆m
(kg/h)Cum. ∆∆∆∆m
(kg/h)FRW = ________
1 Cout= 10
53.57 0.54
2 20 25 -25 0.54
28.57 0.86
3 50 100 50 -50 1.39
-21.43 -1.07
4 100 80 95 15 0.32
-6.43 -0.32
5 150 70 70 0.00
63.57 3.18
6 200 70 -70 3.18
-6.43 -0.32
7 250 60 60 2.86
FRW = ________ 0.54
8 106 53560
Total 275 275
Copyright@Dominic Foo Pinch Analysis for Water Recovery 91
Nearest neighbour algorithmNearest neighbour algorithmNearest neighbour algorithmNearest neighbour algorithmNearest neighbour algorithmNearest neighbour algorithmNearest neighbour algorithmNearest neighbour algorithm
� Apply NNA (Prakash & Shenoy, 2005) based on the 2 general equations:
�Overall material balance:
� Impurity balance:
� Design separately for FWR & RWR.
jjj FFF SKSK N2,SK N1, =+
jjjj CFCFCF SKSKN2SK N2,1NSK N1, =+
Copyright@Dominic Foo Pinch Analysis for Water Recovery 92
Network design with NNANetwork design with NNANetwork design with NNANetwork design with NNANetwork design with NNANetwork design with NNANetwork design with NNANetwork design with NNA
SK1F = 50 t/hC = 20m = 1000
SK2F = 100 t/hC = 50m = 5000
SK3F = 80 t/hC = 100m = 8000
SR1
SR2
SR3
SR4
SK4F = 70 C = 200m = 14000
F = 50
C = 50
F = 100
C = 100
F = 70
C = 150
F = 60
C = 250
RW
FFW = 20 t/h
FRW = 53.57 t/h
FWW = 0 t/h
F = 53.57
C = 10
FWF = 20
C = 0 20
5
From FWR
From FWR
18.75
6.25
6.43
63.57
3.57
70
6.43
25
43.75
31.25
Reg
eneration
53.57
Copyright@Dominic Foo Pinch Analysis for Water Recovery 93
Comparison of various casesComparison of various casesComparison of various casesComparison of various cases
020Regeneration
5070Reuse/recycle
280300Base case
FWW (ton/h)FFW (ton/h)Polley & Polley
7.31.2Regeneration*
8.22.1Reuse/recycle
13.17.0Base case
FWW (kg/s)FFW (kg/s)AN case
* Your own exercise
Copyright@Dominic Foo Pinch Analysis for Water Recovery 94
Concluding remarksConcluding remarksConcluding remarksConcluding remarks
� Process integration techniques provide a bird’s eye view on the maximum extend of water recovery.
� Always proceed from options with lower capital investment/complexity.
� Targeting ahead of design!
Copyright@Dominic Foo Pinch Analysis for Water Recovery 95
ReferencesReferencesReferencesReferencesReferencesReferencesReferencesReferences� El-Halwagi, M. M., Gabriel, F. and Harell, D. (2003). Rigorous Graphical Targeting for Resource Conservation
via Material Recycle/Reuse Networks. Industrial & Engineering Chemistry Research. 42: 4319-4328.
� Foo, D. C. Y., Manan, Z. A. and Tan, Y. L. (2006b). Use Cascade Analysis to Optimize Water Networks, Chemical Engineering Progress. 102(7): 45-52 (July 2006).
� Manan, Z. A., Tan, Y. L. and Foo, D. C. Y. (2004). Targeting the Minimum Water Flowrate Using Water Cascade Analysis Technique AIChE Journal. 50(12): 3169-3183.
� Ng, D. K. S. and Foo, D. C. Y. (2006). Evolution of Water Network with Improved Source Shift Algorithm and Water Path Analysis, Industrial and Engineering Chemistry Research. 45, 8095-8104.
� Ng, D. K. S., Foo, D. C. Y. Tan, R. R. and Tan, Y. L. (2007). Ultimate Flowrate Targeting with Regeneration Placement, Chemical Engineering Research and Design, 85 (A9) 1253–1267.
� Ng, D. K. S., Foo, D. C. Y. and Tan, R. R. (2008). Extension of Targeting Procedure for ‘Ulltmate Flowrate Targeting with Regeneration Placement’ by Ng et al., Che. Eng. Res. Des. 85 (A9): 1253 – 1267. Chemical Engineering Research and Design, 86(10), 1182-1186.
� Polley, G. T. and Polley, H. L. (2000). Design Better Water Networks. Chem Eng Progress. 96(2): 47-52.
� Prakash, R. and Shenoy, U. V. (2005a). Targeting and Design of Water Networks for Fixed Flowrate and Fixed Contaminant Load Operations. Chemical Engineering Science. 60(1): 255-268.
� Prakash, R. and Shenoy, U. V. (2005b). Design and Evolution of Water Networks by Source Shifts. Chemical Engineering Science. 60(7), 2089-2093.
� Rosain, R. M. (1993). Reusing Water in CPI Plants. Chemical Engineering Progress, 89(4): 28-35.
� Smith, R. (2005). Chemical Process Design and Integration. John Wiley & Sons, New York.
� Wang, Y. P. and Smith, R. (1994). Wastewater Minimisation. Chemical Engineering Science. 49: 981-1006.
� Wang, Y. P. and Smith, R. (1995). Wastewater Minimization with Flowrate Constraints. Chemical Engineering Research and Design, Part A. 73: 889-904.
Copyright@Dominic Foo Pinch Analysis for Water Recovery 96
Dominic C. Y. Foo,Dominic C. Y. Foo,Dominic C. Y. Foo,Dominic C. Y. Foo, PhD, PhD, PhD, PhD, PEngPEngPEngPEng�[email protected]