I WAS talking to the energy manager at a large oil refinery.I had worked on the design for a crude unit revamp there the previous year.He casually commented,"By the way,they decided to put E-15B in parallel with E-15A."He paused for a moment when he saw the look on my face."That doesn't matter,does it?""They did what!?"He was rather shaken by my vehement response.A key part of the preheat train design was a new shell-and-tube heat exchanger,E-15B,added in a countercurrent series arrangement with an existing heat exchanger,E-15A,to recover additional heat from a major product rundown stream.As discussed in my March 2022 column,"Squeeze Out the Heat,"https://bit.ly/3tNkhhf,this configuration improves the use of temperature differences,thus increasing heat transfer.Unfortunately,during implementation of the revamp project,the construction team found the piping would be simpler if they placed E-15B in parallel with E-15A,so they installed it that way.That change turned out to be significant:It reduced the heat recovery benefit of the revamp by about 50.
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