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Chalmers
University of
Technology
What is Process Integration?
NTNU
by
Truls Gundersen
Department of Energy and Process Engineering
Norwegian University of Science and Technology (NTNU)
Trondheim, Norway
20.03.13
T. Gundersen
Slide no. 1
Content of the Presentation
n 
n 
Definitions and the birth of Process Integration
Process Integration (PI) as a Term
♦  Heat, Power, Chemical and Equipment Integration
n 
Some early stage Developments, however …
♦  Bodo Linnhoff: “A Historical Overview of early Developments”
n 
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n 
3 Major and Generic Results from Pinch Analysis with
widespread Use in Process Integration
The Tool Box in PI
♦  Graphical Diagrams, Representations and Concept
n 
Various Extensions of Pinch Analysis in PI
♦  Applications, Objectives, Scope, etc.
n 
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Use of Optimization in Process Integration
PI and Global Warming / Emissions Reduction
♦  From Energy Focus to Environmental Concern
20.03.13
T. Gundersen
Slide no. 2
The IEA Definition
of Process Integration
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"Systematic and General Methods for Designing
Integrated Production Systems, ranging from
Individual Processes to Total Sites, with special
emphasis on the Efficient Use of Energy and
reducing Environmental Effects"
P R O C E S S
From an Expert Meeting
in Berlin, October 1993
20.03.13
INTEGRATION
IEA
OECD
T. Gundersen
Slide no. 3
More Descriptions of Process Integration
n 
An Alternative to the IEA Definition:
♦  Process Integration is a Methodology for Analysis, Design and
Optimization of Material and Energy related Production Systems
n 
What is unique in Process Integration (PI)?
♦  Pinch Analysis (PA) was developed in the 1970s/1980s based on
the Discovery of a Heat Recovery Pinch, and PA was the Birth of
PI as a Systems oriented Process Design Methodology
♦  PA/PI represented a Departure from Traditional Design Practice
♦  Improving Process Technologies (following the Learning Curve)
through Operating & Engineering Insight using Design based on
Case Studies was replaced by Systematic Design using Targets
♦  The new Design Methods enabled Step Changes in Performance
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n 
The real Value of Performance Targets ahead of Design:
♦  Removing the Uncertainty among Engineers whether a Process
Design could be further improved and by how much
20.03.13
T. Gundersen
Slide no. 4
The use of Process Integration as a Term
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400"
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Date: 7 March 2013 – Source: Science Direct, Journal papers only
Subjects: Chemical Engineering, Energy, Engineering
20.03.13
T. Gundersen
Slide no. 5
The Title: What is Process Integration?
This Question can be decomposed into
What do we mean by a Process?
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and
What do we mean by Integration?
20.03.13
T. Gundersen
Slide no. 6
A Process can be regarded as a “Converter”
Mechanical
Energy
Com
Thermal Energy
HP, MP, LP
Flue Gas
AP, CW
Refrigerants
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Exp
Energy
Thermal Energy
HP, MP, LP
Cooling
Material
Product(s)
Raw Material(s)
Byproduct(s)
20.03.13
T. Gundersen
Slide no. 7
What is the meaning of Integration?
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Integration means combining Needs/Tasks of “opposite”
kinds so that Savings (or Synergies) can be obtained
Examples of such Integration in the Process Industries:
♦  Heat Integration
•  Cooling & Condensation integrated with Heating & Evaporation
•  Identify near-optimal Level of Heat Recovery
•  Design the corresponding Heat Exchanger Network
♦  Power Integration
•  Expansion integrated with Compression
•  Same Shaft or combined in “Compander”
♦  Chemical Integration
•  Byproducts from one Plant used as Raw Materials in other Plants
•  The Idea of materials integration is used in Industrial “Clusters”
♦  Equipment Integration
•  Multiple Phenomena (Reaction, Separation, Heat Transfer) are
integrated in the same piece of Equipment è Process Intensification
20.03.13
T. Gundersen
Slide no. 8
T (°C)
ST
QH,min
300
270ºC - - - - - - - 250ºC
H1
QRecovery
250
720 kW
230ºC - - - - - - - 210ºC
ΔTmin
200
500 kW
180 kW
150
C2
- 520
200 kW
220ºC - - - - - - - 200ºC
2000 kW
720 kW
- 1200
100
880 kW
180ºC - - - - - - - 160ºC 800 kW
360 kW
50
Pinch
0
T' (°C)
300
C1
440 kW 160ºC - - - - - - - 140ºC
H (kW)
2000
400 kW
+ 400
QC,min
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+ 720
4000
1980 kW
H2
6000
70ºC - - - - - - - - 50ºC
Heat
Integration
QH,min
250
1800 kW
+ 180
220 kW
+ 220
60ºC - - - - - - - - 40ºC
ΔTmin = 20°C
CW
Pinch
180°
200
270°
H1
235.6°
3
mCp
(kW/°C)
180°
2
Ca
160°
18.0
360 kW
150
220°
H2
1
180°
4
100
80°
Cb
60°
22.0
440 kW
210°
50
160°
2
1000 kW
QC,min
Q (kW)
210°
H
190°
1000 kW
0
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500
1500
3
620 kW
T. Gundersen
177.6°
1
4
2200 kW
160°
C2
50°
C1
20.0
50.0
880 kW
160°
Slide no. 9
Simultaneous Heat and Power Integration?
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n 
Feng and Zhu (1997) introduced the Energy Level (Ω)
Energy Level is defined as Exergy/Energy:
♦  For Work and Electricity: Ω = 1
♦  For Heat: Ω = ηC = 1 − T0 / T
♦  For Steady-State Flow Systems: Ω = ΔE / ΔH
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n 
n 
n 
The Energy Level Concept is used to identify Losses in
Energy Quality (which is why Exergy is used)
Energy Level is evaluated at the Entrance and Exit of the
Process Units based on inlet and outlet Process Streams
Energy Level Composite Curves (ELCCs) are Energy
Level vs. Enthalpy Curves plotted in a Cumulative manner
Energy Level of Units will increase or decrease
♦  Synergies possible through Integration?
♦  Problem: High Energy Level caused by Temperature or Pressure?
20.03.13
T. Gundersen
Slide no. 10
ELCCs for a Methanol Process
0.6
Primary Reformer
Primary Reformer, Sec Reformer Shift Reactor
0.5
Sec Reformer Product Cooler
Raw Product Cooler,
Sec Reformer Product Cooler,
Prereformer 1
Energy Level
0.4
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Sec Reformer Product Cooler,
Prereformer 1
Primary Reformer, Sec Reformer
Prereformer 2, Primary Reformer
Prereformer 2
Raw Product Cooler,
Sec Reformer Product Cooler
0.3
Steam Generator, Prereformer 2
Steam Generator, MeOH Reactor Water Jacket, Prereformer 2
Steam Generator, MeOH Reactor Water Jacket
Raw Product Cooler
0.2
Steam Generator, MeOH Reactor
Steam Generator, MeOH Reactor Feed Preheater
Steam Generator, Syn Gas Compressor
Steam Generator, MeOH Recycle Compressor, Syn Gas
0.1
Omega Increasing Units
Steam Generator, Burner, MeOH Recycle Compressor, Syn Gas Compressor
Steam Generator, Burner, MeOH Recycle Compressor
Omega Decreasing Units
Steam Generator
0
0
50
100
150
200
250
300
350
400
450
Cummulative Enthalpy (MW)
Anantharaman R., Abbas O.S., Gundersen T., “Energy Level Composite
Curves – A New Graphical Methodology for the Integration of Energy Intensive
Processes”, Applied Thermal Engineering, vol. 26, pp. 1378-1384, 2006.
20.03.13
T. Gundersen
Slide no. 11
500
Chemical Integration in an Industrial Cluster
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Kaggerud K.H., Bolland O., Gundersen T., “Chemical and Process Integration:
Synergies in Co-Production of Power and Chemicals from Natural Gas with CO2
Capture”, Applied Thermal Engineering, vol. 26, pp. 1345-1352, 2006.
20.03.13
T. Gundersen
Slide no. 12
Equipment Integration – Methyl Acetate
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Eastman
Chemical
Company
Siirola J.J., “Industrial Applications of Chemical Process Synthesis”,
Advances in Chemical Engineering, vol. 23, pp. 1-62, 1996.
20.03.13
T. Gundersen
Slide no. 13
Various Terms in Perspective
Energy
Conservation
Heat Integration
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Process Integration
Process Synthesis
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T. Gundersen
Slide no. 14
Some early stage
Developments
Energy
Equipment
Raw Materials
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From powerful results and insight based on the
Concept of a Heat Recovery Pinch through a
Development along several “axes” to reaching
the Level or Status of a Design Discipline !!
20.03.13
T. Gundersen
Batch
Retrofit
Grassroot
Environment
Bodo Linnhoff
used the
Rubic Cube
to illustrate
Progress
Slide no. 15
3 Major Results from PA with widespread Use in PI
T
QH,min
QC,min
n 
C
Heat
Pinch
Water
Pinch
Watermin
H
m
The Concept of Composite Curves (Cumulative Plots)
♦  Applicable whenever an “Amount” has a “Quality”
♦  Heat & Temperature, Mass & Concentration (Chemical Potential),
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Refinery Gases & H2 Purity (and Pressure), Money & Time, etc.
n 
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Targets for Best Performance ahead of Design
Decomposition of Systems into Surplus and Deficit Regions
♦  PDM for Grassroot Design develops Separate Networks
♦  Process Modifications guided by the Plus/Minus Principle
♦  Appropriate Placement (or Integration) of Distillation Columns,
Evaporators, Heat Engines (Steam Turbines) and Heat Pumps
20.03.13
T. Gundersen
Slide no. 16
“Correct” Integration and Appropriate Placement
Process
Cascade
Distillation
Column
Heat
Pump
Steam
Turbine
QHP,out
QST,in
QH,min
QReboiler
Above
Pinch
Q=0
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WST
WHP
Below
Pinch
QCondenser
QHP,in
QST,out
QC,min
Simple Rule: “Connect Sources with Sinks”
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T. Gundersen
But: TSource > TSink
Slide no. 17
Diagrams, Representations and Concepts in PI
n 
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Graphical Diagrams
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
n 
Composite Curves
Grand Composite Curve
Energy Target Plot
Area/Energy Plot
Driving Force Plot
Column Grand Composite Curve
Exergy Composite Curves
Exergy Grand Composite Curve
Column Grand Composite Curve
Total Site Source & Sink Curves
More?
Representations & Concepts
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
♦ 
Process & Utility Pinch
Feasibility Table
Problem Table
Heat Cascade
Grid Diagram
Penalty Heat Flow Diagram
Bipartite Graph
Heat Load Loops
Heat Load Paths
Rubic Cube and the “Onion”
More?
Important Tools for Analysis, Design and Optimization
as well as for Learning and Communication
20.03.13
T. Gundersen
Slide no. 18
Expansions in Process Integration
based on Pinch Analysis
and using Analogies
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20.03.13
n 
Applications Areas
n 
Objectives
n 
Scope
n 
Type of Plants
n 
Type of Projects
n 
Thermodynamics
T. Gundersen
Slide no. 19
n 
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Expansions
Application Areas
w  From Heat Pinch for Heat Recovery
and CHP in Thermal Energy Systems
w  to Mass Pinch for Mass Transfer /
Mass Exchange Systems
w  to Water Pinch for Wastewater
Minimization and Distributed
Effluent Treatment Systems
w  to Hydrogen Pinch for Hydrogen
Management in Oil Refineries
w  to Oxygen Pinch for Wastewater
Bio-Treatment Plants
w  to Carbon Pinch to satisfy Energy
Requirements while meeting CO2
Emission Limits in the Energy Sector
20.03.13
T. Gundersen
of PA & PI
Slide no. 20
Expansions
n 
of PA & PI
Objectives
w  from Energy Cost
w  to Equipment Cost
w  to Total Annualized Cost
w  and also Operability, including
Ÿ  Flexibility
Ÿ  Controllability
Ÿ  Switchability
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à  Start-up & Shut-down
à  New Operating Conditions
w  and finally Environment, including
Ÿ  Emissions Reduction
Ÿ  Waste Minimization
20.03.13
T. Gundersen
Slide no. 21
Expansions
n 
of PA & PI
Scope
w  from Heat Exchanger Networks
w  to Separation Systems, especially
Ÿ  Distillation and Evaporation (heat driven)
w  to Reactor Systems
w  to Heat & Power, including
Ÿ  Steam & Gas Turbines and Heat Pumps
w  to Utility Systems, including
Ÿ  Steam Systems, Furnaces, Refrigeration Cycles
w  to Entire Processes
w  to Total Sites
w  to Regions
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20.03.13
T. Gundersen
Slide no. 22
Expansions
n 
of PA & PI
Plants
w  from Continuous
w  to Batch and Semi-Batch
n 
Projects
w  from New Design
w  to Retrofit
w  to Debottlenecking
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n 
Thermodynamics
w  from Simple 1st Law Considerations
w  to Various 2nd Law Applications
Ÿ  Exergy in Distillation and Refrigeration
20.03.13
T. Gundersen
Slide no. 23
Process Integration Methodologies
Expert Systems
qualitative
Knowledge
Based Systems
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automatic
Optimization
Methods
Heuristic
Methods
Hierarchical
Analysis
interactive
Thermodynamic
Methods
quantitative
Stochastic Methods
Mathematical Programming
20.03.13
Rules of Thumb
T. Gundersen
Pinch Analysis
Exergy Analysis
Slide no. 24
Limitations in Pinch Analysis & the PDM
n 
Rigor sometimes replaced by Heuristic Rules
♦  The (N – 1) Rule for minimum Number of Units
♦  The “Bath” formula for minimum total Heat Transfer Area
n 
The Composite Curves have their Limitations
♦  Cannot handle Forbidden Matches between Streams
♦  Simple Rules for Appropriate Placement do not work when
Distillation Columns are included in the Composite Curves
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n 
The Pinch Design Method is Sequential in Nature
♦  Targeting è Design è Optimization (Evolution)
♦  One Match at a time, one Loop at a time, one Path at a time, etc.
♦  è Unable to properly handle Multiple Trade-offs
n 
Pinch Decomposition guides Correct Integration, but
♦  In Network Design, less Costly and less Complex Designs can
be found by actually ignoring strict Pinch Decomposition
n 
Time consuming but normally results in “good” Designs
20.03.13
T. Gundersen
Slide no. 25
CMU
Why not use Optimization?
UMIST
T (°C)
HP
250
200
150
LP
Energy
Minimum Area
=> Counter-Current or
“Vertical” Heat Transfer
100
50
CW
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MILP
Units
0
H (kW)
2000
MINLP
NLP
4000
6000
Targeting
Design
Evolution
Area Considerations using
a “vertical” MILP Model?
Area/TAC
Software: MAGNETS
Transshipment Models (LP & MILP)
Clever Stream Superstructure (NLP)
20.03.13
Gundersen T., Grossmann I.E., “Improved Optimization
Strategies for Automated Heat Exchanger Networks
through Physical Insights”, Comput. chem. Engng., vol.
14, no. 9, pp. 925-944, 1990.
T. Gundersen
Slide no. 26
UMIST Comments after Sabbatical
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Promoting Mathematical Programming
was quite challenging in those Days !
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T. Gundersen
Slide no. 27
The Sequential Framework – SeqHENS
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Heat Transfer Area: Loops 1 & 2
n 
# of Heat Exchangers:
Loop 3
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Energy Consumption:
Loop 4
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Compromise between Pinch Design and MINLP Methods
Surprisingly few Iterations thanks to excessive use of Insight
Anantharaman R., Gundersen T., “The Sequential Framework for Heat Exchanger
Network Synthesis – Network Generation and Optimization”, PRES’2007, Ischia
Island, Chemical Engineering Transactions, vol. 12, pp. 19-24, 2007
20.03.13
T. Gundersen
Slide no. 28
Process Integration and Global Warming
n 
The IEA: 3 main Measures to reduce CO2 Emissions
♦  Energy Efficiency (short term, even profitable?)
♦  Carbon Capture & Storage (medium term, expensive!)
♦  Renewable Energy Forms (long term, expensive?)
n 
Public Discussion in the US (2012)
♦  Energy Efficiency is the 5th Energy Form
♦  Following Oil, Gas, Coal and Nuclear
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n 
An obvious Observation
♦  “The cleanest Energy is the one that is not used”
n 
A Shift of Focus in Process Integration
♦  From Energy Focus in the 1970s and 1980s (Availability
and Cost) to Environmental Concern in the 1990s and later
n 
Global Warming – A new Opportunity for PI?
♦  Energy Efficiency is a Core Activity in Process Integration
20.03.13
T. Gundersen
Slide no. 29
Pinch Analysis developed by an “Accident”?
Bodo Linnhoff, PhD Thesis, University of Leeds, April 1979:
“Thermodynamic Analysis in the Design of Process Networks”
Abstract: “This thesis discusses the use of thermodynamic Second
Law analysis in the context of chemical process design”
2nd Law of Thermodynamics for Open/Flowing Systems:
Q j
dScv
= ∑ + ∑ m i ⋅ si − ∑ m ⋅ se + σ cv
dt
j Tj
i
e
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Entropy (S) is the twin brother/sister of Exergy (Ex)
⎛ T0 ⎞
dExcv
dVcv ⎞
⎛ 


= ∑ ⎜ 1− ⎟ ⋅ Q j − ⎜ Wcv − p0 ⋅
+ ∑ m i ⋅ e f ,i − ∑ m ⋅ e f ,e − Ex
⎟
d
⎝
dt
Tj ⎠
dt ⎠ i
j ⎝
e
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T. Gundersen
Slide no. 30