Chapter 13 Pinch Technology

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Chapter 13Pinch Technology

• Don Scott
• 3/9/6
• ENCH 430

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Pinch Point

• In a system, a point where energy or mass
  exchange is at a minimum is the pinch point.
• A pinch point needs to be located and used to
  design the system.

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Heat Integration- Matching points of heat
addition and heat loss

1. Choose a minimum approach temperature.
2. Construct a temperature interval diagram.
3. Construct cascade diagram-minimum utility
   requirement, pinch temperatures.
4. Calculate minimum no. of heat exchangers above
   and below pinch.
5. Construct the heat exchanger network.

Pages 462-473
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Estimate Area

• A(Q)/(Udelta TlmF)
• A heat transfer area
• Q amount of heat to be transferred
• U film heat transfer coefficient
• delta Tlm log-mean temperature.
• F log-mean temperature correction factor

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Equivalent Annual Operating Cost

• EAOCFCI(i(1i)n)/((1i)n-1)utility costs
• FCI total cost of network
• n number of years
• ibefore tax hurdle rate

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Other considerations

• Material
• Operating pressure
• Multiple Utilities
• Phase Changes

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Mass Exchange

• Analogous to heat exchange.
• Pages 500-509