(293c) High Energy Saving By Commercially Operated Heat Integrated Distillation Column with New Heat Integration Arrangement

In the conventional heat integrated distillation columns (HIDiC), the rectifying and the stripping section are installed in parallel, and the heat is internally transferred from the pressurized rectifying stages to the stripping stages at the physically same elevation. In such process scheme, the amount of heat exchanged between stages fully relies on the temperature profile of both sections. Author developed the interactive graphical design method to determine the appropriate heat exchange arrangement on the base of Ponchon-Savarit H-xy diagram in the previous paper [1]. The results of case studies suggested that heat exchanges should be made among the limited number of stages discretely. Moreover, the stages involved in the heat exchange are not at the same level.

Such new structure of HIDiC having the appropriate heat exchanger arrangement has been applied in commercial operation purpose fractionator in Maruzen Petrochemical Co., Ltd. in Japan. In that novel HIDiC, a part of the rectifying section is operated at high pressure. While the heat of overhead vapor of the rectifying section is supplied to the three different positions in the stripping section, the whole vapor at intermediate stage in the rectifying section, i.e. the overhead vapor of the low pressure column is compressed and the heat of this vapor is supplied to the reboiler stage of the stripping section. The plant has been in commercial operation since late 2^nd quarter in 2016 and has achieved more than 50% energy conservation compared to the conventional process. Moreover, it has demonstrated that the novel HIDiC can operate without any external input to the reboiler at steady state operation. In this report, the operating results will be presented and the evaluation will be made in comparison with other heat pump distillation systems.

Reference

1. Wakabayashi, T., and S. Hasebe, Higher Energy Saving with New Heat Integration Arrangement in Heat-integrated Distillation Column. AIChE Journal, 2015. 61(10): p. 3479-3488.