3 Process Integration for Efficient Use of Energy 1.pdf

Smith: Chemical Process Design and Integration (Chapters 16,18) Kemp: Pinch Analysis and Process Integration (Chapter 9)

Process Integration for Efficient Use of Energy

Cheng-Liang Chen

PSE

LABORATORY

Department of Chemical Engineering National TAIWAN University

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Important Global Crises Ten Most Important Global Crises: Energy Water Food • Environment Poverty Terrorism Disease Education Democracy Population

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Outline ➢ Systematic Approach for Chemical Process Design How do we go about the design of a chemical process? ➢ What Is Process Integration? Onion model for process integration ➢ Pinch Analysis: Targeting Heat Recovery in Processes ➢ The Pinch Design Method for Heat Recovery Systems ➢ A Pinch Study Performed on A Major Operating Plant ➢ Utility Selection for Individual Processes ➢ Putting It into Practice ➢ Concluding Remarks

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Systematic Approach for

Chemical Process Design

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Chemical Process Design How do we go about the design of a chemical process?

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Chemical Process Design How do we go about the design of a chemical process?

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Chemical Process Design How do we go about the design of a chemical process?

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Chemical Process Design How do we go about the design of a chemical process?

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Chemical Process Design How do we go about the design of a chemical process?

Finished Process ? UNFORTUNATELY This is inefficient in energy use! So let’s consider heat recovery to reduce the energy consumption

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Chemical Process Design How do we go about the design of a chemical process?

Some streams need to be cooled down and some need to be heated up

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Chemical Process Design How do we go about the design of a chemical process?

Recover heat between a stream that needs to be cooled down and one that needs to be heated up

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Chemical Process Design How do we go about the design of a chemical process?

· · · and more heat recovery completes the design

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Chemical Process Design How do we go about the design of a chemical process?

different possibilities for heat integration

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Chemical Process Design How do we go about the design of a chemical process?

Changing the reactor dictates a different separation and recycle problem

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Chemical Process Design How do we go about the design of a chemical process?

Changing the reactor dictates a different separation and recycle problem

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Chemical Process Design How do we go about the design of a chemical process?

· · · leads to a different separation system and different heat recovery

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Chemical Process Design How do we go about the design of a chemical process?

· · · leads to a different separation system and different heat recovery

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What Is Process Integration ?

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What Is Process Integration? First choose a series of processing steps

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What Is Process Integration? Then connect these processing steps together

To give an integrated manufacturing system that is: Environmentally acceptable; Safe; Profitable; Operable

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What Is Process Integration? First Process Integration:

Then Process Simulation:

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Onion Model for

Process Integration

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Onion Model Start With The Reactor

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Onion Model Then Add Separation System and Connect Up Recycle

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Onion Model Recover Heat Where Possible

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Onion Model Dictate The Need for External Utilities

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Hierarchy of Process Design Reactor Design ⇓ Separation System Design ⇓ HEN Design ⇓ Utility System Design Process design is strongly coupled with Heat Exchanger Networks

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Process Integration (for Heat Recovery) ➢ Process Integration: using process streams to heat and cool other streams ☞ Hot streams gives off heat to another streams ☞ Cold streams absorbs heat from another streams ➢ Additional heating or cooling is done using utility streams ➢ Heat recovery reduces utility requirements, and therefore operating costs

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Process Integration (for Heat Recovery) Ex: The Front End of A Specialty Chemicals Process

Six heat transfer units (i.e. heaters, coolers and exchangers) are used and the energy requirements are 1, 722 kW for heating and 654 kW for cooling.

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Process Integration (for Heat Recovery) Ex: The Front End of A Specialty chemicals Process

The alternative flowsheet uses only four heat transfer units and the utility heating load is reduced by about 40% (1, 068 kW) with cooling no longer required.

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Thank You for Your Attention Questions Are Welcome