what is process integration? - chalmers tekniska … is process integration? by truls gundersen...

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20.03.13 T. Gundersen Slide no. 1

What is Process Integration?

by

Truls Gundersen Department of Energy and Process Engineering

Norwegian University of Science and Technology (NTNU) Trondheim, Norway

Chalmers University of Technology

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Content of the Presentation n  Definitions and the birth of Process Integration n  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  3 Major and Generic Results from Pinch Analysis with

widespread Use in Process Integration n  The Tool Box in PI

♦  Graphical Diagrams, Representations and Concept n  Various Extensions of Pinch Analysis in PI

♦  Applications, Objectives, Scope, etc. n  Use of Optimization in Process Integration n  PI and Global Warming / Emissions Reduction

♦  From Energy Focus to Environmental Concern

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P R O C E S S I N T E G R A T I O N

IEA OECD

The IEA Definition of Process Integration

From an Expert Meeting in Berlin, October 1993

"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"

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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 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

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0"200"400"600"800"1000"1200"1400"1600"1800"

1960)69"

1970)79"

1980)89"

1990)99"

2000)2004"

2005)2009"

2010)Present"

The use of Process Integration as a Term

Date: 7 March 2013 – Source: Science Direct, Journal papers only Subjects: Chemical Engineering, Energy, Engineering

0 8 121

714 651

1420 1666

2071

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The Title: What is Process Integration?

This Question can be decomposed into

What do we mean by a Process?

and

What do we mean by Integration?

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Energy

Material

Com Exp

Raw Material(s) Product(s)

Byproduct(s)

Thermal Energy HP, MP, LP Flue Gas AP, CW Refrigerants

Thermal Energy HP, MP, LP

Cooling

Mechanical Energy

A Process can be regarded as a “Converter”

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What is the meaning of Integration? n  Integration means combining Needs/Tasks of “opposite”

kinds so that Savings (or Synergies) can be obtained n  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

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Heat Integration

2000 4000 6000 0

300

250

200

150

100

50

T (°C)

H (kW)

QH,min

QC,min

Pinch

QRecovery

ΔTmin

Pinch 180°

C2 210° 160°

C1 210° 50°

H2 220° 60°

H1 270° 160°

160°

Ca

4

4

H

1

1 3

3

2

2

190° 177.6°

1000 kW

1000 kW 620 kW 880 kW

Cb

360 kW

440 kW

2200 kW

160°

180°

180°

80°

235.6°

mCp (kW/°C)

18.0

22.0

20.0

50.0

270ºC - - - - - - - 250ºC

230ºC - - - - - - - 210ºC

220ºC - - - - - - - 200ºC

180ºC - - - - - - - 160ºC

160ºC - - - - - - - 140ºC

70ºC - - - - - - - - 50ºC

H1

H2

CW

C1

C2

ST

720 kW

180 kW

720 kW

880 kW

440 kW

1980 kW

500 kW

200 kW

800 kW

1800 kW

+ 720

- 520

- 1200

2000 kW

400 kW

+ 180

+ 220

+ 400

60ºC - - - - - - - - 40ºC

360 kW

220 kW

ΔTmin = 20°C 300

250

200

150

100

50

T' (°C)

Q (kW)

500 1500 0

QH,min

QC,min

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Simultaneous Heat and Power Integration? n  Feng and Zhu (1997) introduced the Energy Level (Ω) n  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

n  The Energy Level Concept is used to identify Losses in Energy Quality (which is why Exergy is used)

n  Energy Level is evaluated at the Entrance and Exit of the Process Units based on inlet and outlet Process Streams

n  Energy Level Composite Curves (ELCCs) are Energy Level vs. Enthalpy Curves plotted in a Cumulative manner

n  Energy Level of Units will increase or decrease ♦  Synergies possible through Integration? ♦  Problem: High Energy Level caused by Temperature or Pressure?

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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.

0

0.1

0.2

0.3

0.4

0.5

0.6

0 50 100 150 200 250 300 350 400 450 500

Cummulative Enthalpy (MW)

Ene

rgy

Leve

l

Omega Increasing Units

Omega Decreasing Units

Raw Product Cooler

Raw Product Cooler, Sec Reformer Product Cooler

Raw Product Cooler, Sec Reformer Product Cooler,Prereformer 1

Sec Reformer Product Cooler,Prereformer 1

Sec Reformer Product Cooler

Steam Generator

Steam Generator, Burner, MeOH Recycle Compressor

Steam Generator, Burner, MeOH Recycle Compressor, Syn Gas Compressor

Steam Generator, MeOH Recycle Compressor, Syn Gas

Steam Generator, Syn Gas CompressorSteam Generator, MeOH Reactor Feed Preheater

Steam Generator, MeOH Reactor

Steam Generator, MeOH Reactor Water Jacket

Steam Generator, MeOH Reactor Water Jacket, Prereformer 2

Steam Generator, Prereformer 2

Prereformer 2

Prereformer 2, Primary Reformer

Primary Reformer, Sec Reformer

Primary Reformer, Sec Reformer Shift Reactor

Primary Reformer

ELCCs for a Methanol Process

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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.

Chemical Integration in an Industrial Cluster

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Equipment Integration – Methyl Acetate

Siirola J.J., “Industrial Applications of Chemical Process Synthesis”, Advances in Chemical Engineering, vol. 23, pp. 1-62, 1996.

Eastman Chemical Company

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Process Synthesis

Process Integration

Heat Integration


Various Terms in Perspective

Energy Conservation

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Some early stage Developments

Energy

Equipment

Raw Materials

Environment

Grassroot

Retrofit

Batch Bodo Linnhoff

used the Rubic Cube to illustrate

Progress

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 !!

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3 Major Results from PA with widespread Use in PI

n  The Concept of Composite Curves (Cumulative Plots) ♦  Applicable whenever an “Amount” has a “Quality” ♦  Heat & Temperature, Mass & Concentration (Chemical Potential),

Refinery Gases & H2 Purity (and Pressure), Money & Time, etc. n  Targets for Best Performance ahead of Design n  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

T

H

C

m

Heat Pinch

Water Pinch

QC,min

QH,min

Watermin

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Above Pinch

Below Pinch

QH,min

QC,min

Q = 0

Process Cascade

QReboiler

QCondenser

Distillation Column

Heat Pump

QHP,out

QHP,in

WHP

Steam Turbine

QST,in

QST,out

WST

“Correct” Integration and Appropriate Placement

Simple Rule: “Connect Sources with Sinks” But: TSource > TSink

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Diagrams, Representations and Concepts in PI

n  Graphical Diagrams ♦  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?

n  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

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Expansions in Process Integration based on Pinch Analysis

and using Analogies

n  Applications Areas

n  Objectives

n  Scope

n  Type of Plants

n  Type of Projects

n  Thermodynamics

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n  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

Expansions of PA & PI

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n  Objectives w  from Energy Cost w  to Equipment Cost w  to Total Annualized Cost w  and also Operability, including

�  Flexibility �  Controllability �  Switchability

à  Start-up & Shut-down à  New Operating Conditions

w  and finally Environment, including �  Emissions Reduction �  Waste Minimization

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n  Scope w  from Heat Exchanger Networks w  to Separation Systems, especially

�  Distillation and Evaporation (heat driven) w  to Reactor Systems w  to Heat & Power, including

�  Steam & Gas Turbines and Heat Pumps w  to Utility Systems, including

�  Steam Systems, Furnaces, Refrigeration Cycles w  to Entire Processes w  to Total Sites w  to Regions

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n  Plants w  from Continuous w  to Batch and Semi-Batch

n  Projects w  from New Design w  to Retrofit w  to Debottlenecking

n  Thermodynamics w  from Simple 1st Law Considerations w  to Various 2nd Law Applications

�  Exergy in Distillation and Refrigeration

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Process Integration Methodologies

Hierarchical Analysis

Heuristic Methods

Knowledge Based Systems

Optimization Methods

Thermodynamic Methods

Pinch Analysis Exergy Analysis

Stochastic Methods Mathematical Programming

Rules of Thumb Expert Systems qualitative

quantitative

interactive automatic

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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 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

NTNU 2000 4000 6000 0

250

200

150

100

50

T (°C)

H (kW) CW

HP


Why not use Optimization?

MILP

LP

NLP

Energy

Units

Area/TAC

Software: MAGNETS

Transshipment Models (LP & MILP) Clever Stream Superstructure (NLP)

MINLP

Minimum Area => Counter-Current or

“Vertical” Heat Transfer

Area Considerations using a “vertical” MILP Model?

Targeting

Design

Evolution

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.

CMU UMIST

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UMIST Comments after Sabbatical

Promoting Mathematical Programming was quite challenging in those Days !

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The Sequential Framework – SeqHENS

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

Compromise between Pinch Design and MINLP Methods Surprisingly few Iterations thanks to excessive use of Insight

n  Heat Transfer Area: Loops 1 & 2

n  # of Heat Exchangers: Loop 3

n  Energy Consumption: Loop 4

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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

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

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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:

dScvdt

=Qj

Tj

+ mi ⋅ si − m ⋅ se + σ cve∑

i∑

j∑

Entropy (S) is the twin brother/sister of Exergy (Ex)

dExcvdt

= 1− T0Tj

⎛

⎝⎜⎞

⎠⎟⋅ Qj − Wcv − p0 ⋅

dVcvdt

⎛⎝⎜

⎞⎠⎟ +

mi ⋅ef ,i − m ⋅ef ,e − Exde∑

i∑

j∑

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