chapter 13 pinch technology don scott 3/9/6 ench 430
TRANSCRIPT
Chapter 13Pinch Technology
Don Scott
3/9/6
ENCH 430
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.
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
Estimate Area
• A=(Q)/(U*delta Tlm*F)
• 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
Equivalent Annual Operating Cost
• EAOC=FCI(i(1+i)n)/((1+i)n-1)+utility costs
• FCI= total cost of network
• ‘n= number of years
• i=before tax hurdle rate
Other considerations
• Material
• Operating pressure
• Multiple Utilities
• Phase Changes
Mass Exchange
• Analogous to heat exchange.
• Pages 500-509