Heat exchangers and pinch integration
Passing heat between process streams, and redesigning plants so hot and cold streams share heat.
Recovery and reuse · Heat to heat · No. 123
- Recovery and reuse
- Heat grade: All grades
One paper mill's plate heat exchanger paid for itself in under a month, by swapping heat between its own pipes.
Chart: Illustration: Heat exchangers and pinch integration
Where it comes from
Chart: Map of where it comes from
A heat exchanger moves heat from a stream that must be cooled to one that must be heated without letting them touch. Pinch analysis matches every such stream in a whole plant.
Three things to know
- Plate exchangers have three or more times the heat transfer coefficient of shell-and-tube units, so they fit in far less space.
- Heat saved by 12 US projects cost about USD 0.05 per therm over their lives, against gas at USD 5.66 per MMBtu.
- Fouling remains unsolved: a review of 231 patents found it mostly handled after the fact.
The journey
- 1 Hot streamProcess fluid that must be cooled
- 2 ExchangerPlates or tubes pass heat across
- 3 Cold streamFeed or water that needed heating
- 4 Pinch designPlant-wide matching of every hot, cold stream
- 5 Less fuelSmaller boilers and cooling towers needed