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18 Heat integration

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Product-Driven Process Design
This chapter is in the book Product-Driven Process Design
18 Heat integration18.1 Pinch analysisHeatandpowerintegrationisconcernedwithusingtheenergyinthehigh-temperaturestreams that need to be cooled or condensed to heat and/or vaporize the cold streamsand provide power to compressors for turbines and heat engines where possible. Inmost designs it is common to disregard power demands favoring the design of an ef-fective network by heat exchangers without using the energy of the high-temperaturestreams to produce power. In this chapter we will discuss how pinch analysis canbe used as a tool to achieve heat integration in the process. This chapter is basedon the extensive work of Linnhoff and Townsend andThe chemical engineers re-source.The term “pinch analysis” was first coined in the 1970s by Linnhoff to represent anew set of thermodynamically based methods that guarantee minimum energy levelsin the design of heat exchanger networks (HENs). Since the 1970s it has become a stan-dard method in process design. The term “pinch analysis” is often used to represent theapplication of the tools and algorithms for studying industrial processes.Pinchtechnologypresentsasimplemethodologyforsystematicallyanalyzingchem-ical processes and the surrounding utility systems with the help of the first and secondlaws of thermodynamics.The first law of thermodynamics provides the energy equation for calculating theenthalpy changes (H) in the streams passing through a heat exchanger. The second lawdetermines the direction of heat flow. That is, heat energy may only flow in the direc-tion of hot to cold. This prohibits “temperature cross-overs” of the hot and cold streamprofiles through the exchanger unit.In a heat exchanger a hot stream cannot be cooled below the cold stream supplytemperature, nor can a cold stream be heated to a temperature higher than the supplytemperature of the hot stream. In practice the hot stream can only be cooled to a tem-peraturedefinedbythe“temperatureapproach”oftheheatexchanger.Thetemperatureapproach is the minimum allowable temperature difference (ΔTmin) in the stream tem-perature profiles for the heat exchanger unit. The temperature level at which ΔTminisobserved in the process is referred to as “pinch point.” The pinch defines the minimumdriving force allowed in the exchanger unit.18.2 Motivation for heat integration by pinch analysisConsider the simple process in Figure 18.1, where the feed stream to a reactor is heatedbefore the inlet to a reactor and the product stream has to be cooled. The heatingand cooling are done by use of steam (Heat Exchanger-1) and cooling water (HeatExchanger-2).https://doi.org/10.1515/9783111014951-018
© 2023 Walter de Gruyter GmbH, Berlin/Boston

18 Heat integration18.1 Pinch analysisHeatandpowerintegrationisconcernedwithusingtheenergyinthehigh-temperaturestreams that need to be cooled or condensed to heat and/or vaporize the cold streamsand provide power to compressors for turbines and heat engines where possible. Inmost designs it is common to disregard power demands favoring the design of an ef-fective network by heat exchangers without using the energy of the high-temperaturestreams to produce power. In this chapter we will discuss how pinch analysis canbe used as a tool to achieve heat integration in the process. This chapter is basedon the extensive work of Linnhoff and Townsend andThe chemical engineers re-source.The term “pinch analysis” was first coined in the 1970s by Linnhoff to represent anew set of thermodynamically based methods that guarantee minimum energy levelsin the design of heat exchanger networks (HENs). Since the 1970s it has become a stan-dard method in process design. The term “pinch analysis” is often used to represent theapplication of the tools and algorithms for studying industrial processes.Pinchtechnologypresentsasimplemethodologyforsystematicallyanalyzingchem-ical processes and the surrounding utility systems with the help of the first and secondlaws of thermodynamics.The first law of thermodynamics provides the energy equation for calculating theenthalpy changes (H) in the streams passing through a heat exchanger. The second lawdetermines the direction of heat flow. That is, heat energy may only flow in the direc-tion of hot to cold. This prohibits “temperature cross-overs” of the hot and cold streamprofiles through the exchanger unit.In a heat exchanger a hot stream cannot be cooled below the cold stream supplytemperature, nor can a cold stream be heated to a temperature higher than the supplytemperature of the hot stream. In practice the hot stream can only be cooled to a tem-peraturedefinedbythe“temperatureapproach”oftheheatexchanger.Thetemperatureapproach is the minimum allowable temperature difference (ΔTmin) in the stream tem-perature profiles for the heat exchanger unit. The temperature level at which ΔTminisobserved in the process is referred to as “pinch point.” The pinch defines the minimumdriving force allowed in the exchanger unit.18.2 Motivation for heat integration by pinch analysisConsider the simple process in Figure 18.1, where the feed stream to a reactor is heatedbefore the inlet to a reactor and the product stream has to be cooled. The heatingand cooling are done by use of steam (Heat Exchanger-1) and cooling water (HeatExchanger-2).https://doi.org/10.1515/9783111014951-018
© 2023 Walter de Gruyter GmbH, Berlin/Boston

Chapters in this book

  1. Frontmatter I
  2. Foreword VII
  3. Contents IX
  4. Part I: Product-centred Design
  5. 1 Introduction 1
  6. 2 Performance products in a challenging environment 9
  7. 3 A structured approach for product-driven process design of consumer products 86
  8. 4 Formulation of design problems and identification of consumer wants 114
  9. 5 Project management and reporting 139
  10. 6 Product function and generation of ideas 158
  11. 7 Brainstorming techniques 177
  12. 8 Network of tasks, mechanisms and operational window 189
  13. 9 Equipment selection and design 207
  14. 10 Multiproduct and multiproduct–equipment integration 255
  15. 11 Molecular product design 264
  16. Part II: Process Design Principles
  17. 12 Process synthesis 281
  18. 13 Process simulation 296
  19. 14 Reactor design 353
  20. 15 Batch process design 385
  21. 16 Separation train design 404
  22. 17 Plant-wide control 431
  23. 18 Heat integration 449
  24. 19 Process and product safety 464
  25. 20 Techno-economical evaluation of projects 507
  26. 21 Design for sustainability 529
  27. 22 Optimization 539
  28. 23 Enterprise-wide optimization 551
  29. A Appendix 565
  30. Index 569
Readers are also interested in:
https://doi.org/10.1515/9783111014951-018

Chapters in this book

  1. Frontmatter I
  2. Foreword VII
  3. Contents IX
  4. Part I: Product-centred Design
  5. 1 Introduction 1
  6. 2 Performance products in a challenging environment 9
  7. 3 A structured approach for product-driven process design of consumer products 86
  8. 4 Formulation of design problems and identification of consumer wants 114
  9. 5 Project management and reporting 139
  10. 6 Product function and generation of ideas 158
  11. 7 Brainstorming techniques 177
  12. 8 Network of tasks, mechanisms and operational window 189
  13. 9 Equipment selection and design 207
  14. 10 Multiproduct and multiproduct–equipment integration 255
  15. 11 Molecular product design 264
  16. Part II: Process Design Principles
  17. 12 Process synthesis 281
  18. 13 Process simulation 296
  19. 14 Reactor design 353
  20. 15 Batch process design 385
  21. 16 Separation train design 404
  22. 17 Plant-wide control 431
  23. 18 Heat integration 449
  24. 19 Process and product safety 464
  25. 20 Techno-economical evaluation of projects 507
  26. 21 Design for sustainability 529
  27. 22 Optimization 539
  28. 23 Enterprise-wide optimization 551
  29. A Appendix 565
  30. Index 569
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