Improvement of natural gas liquid recovery energy efficiency through thermally coupled distillation arrangements

The depropanizing, debutanizing, and deisobutanizing fractionation steps of processing natural gas liquids were improved through studying complex distillation arrangements, including the double prefractionator arrangement (DPA), the double dividing wall column (DDWC) arrangement, and the Agrawal arrangement. The DPA and DDWC arrangements were obtained from an initial conventional column sequence, and both offer benefits by decreasing reboiler and condenser power consumption. Reducing the number of columns and their diameters in the DDWC arrangement can potentially reduce construction costs. Inter-reboiling of the bottom section of the second dividing wall column improved the performance of the DDWC. (c) 2011 Curtin University of Technology and John Wiley & Sons, Ltd.