Utility bounds for nonconstant QΔT for heat-integrated distillation sequence synthesis

✍ Scribed by A. W. Westerberg; M. J. Andrecovich

• Publisher: American Institute of Chemical Engineers
• Year: 1985
• Tongue: English
• Weight: 359 KB
• Volume: 31
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690310909

✦ Synopsis

In earlier work the authors presented a simple method to synthesize heat-integrated distillation sequences through the use of simple sketches on a diagram displaying temperature vs. enthalpy. Embedded in that work is the useful but incorrect assumption that the reboiler/condenser heat loads and the temperaturedifference across the column are independent of the temperature (pressure) level at which the column is operated. This assumption of constancy is removed here, and it is shown how to calculate the minimum utility target using a small linear programming formulation. It is also shown how to use the results of this calculation to synthesize distillation sequences that approach the bound discovered. For the example problems solved, the minimum utility target calculated increases about 25 to 60% over that calculated assuming constant QAT. The sequences synthesized based on this improved target are virtually the same as the constant QATmethod produces, suggesting that the earlier method is indeed a useful approach.