دانلود رایگان مقاله انگلیسی تحلیل عملکردی ستون مدار همبسته گرما با پمپاژ گرما - الزویر 2019

ABSTRACT

In this work, a heat pump system in the form of vapor recompression (VRC) is introduced in the dividing wall column (DWC) to further improve its thermal efficiency performance. It is a fact that the temperature difference is reasonably large between the top and bottom of a DWC, which typically produces at least a single side product. This may lead to a very large compression ratio (CR), with which, the operation of VRC in the DWC becomes quite complicated and may not be economically so attractive. To improve this situation, the vapor recompression mechanism is further proposed between the side stream and reboiler drum of the DWC column. Utilizing the latent heat of a vapor stream from an intermediate tray in liquid reboiling of the stripper, this side vapor recompressed DWC (SVR-DWC) configuration can reduce the utility consumption and thus improves its energetic and economic potential substantially. This proposed thermally integrated scheme is finally illustrated by a ternary system.

7. Conclusions

In this article, the vapor recompression heat pump is introduced in the DWC column to reduce the heat irreversibility of distillation operation. There are two types of thermal coupling proposed under the VRC mechanism between the heat source and heat sink. They are the overhead vapor recompressed and the side vapor recompressed DWC. The former scheme operates the VRC at a very large CR because of its involvement between the two ends of the column. As a consequence, the OVR-DWC structure may not be so attractive proposition from industrial perspective, although it can show a better energy efficiency performance over the DWC-alone at the expense of an increased cost and complicated compression operation. On the other hand, in the SVRDWC configuration, the CR remains reasonably low because of its thermal pairing between the intermediate and bottom streams, which would lead to secure a remarkable savings. For the representative ethanol/water/ethylene glycol system, the DWC-alone shows a reasonable energy household and a better economic figure than the conventional two column system (CTCS). Further, it is observed that the OVR-DWC provides a better energy savings but a worse economic performance over the DWC-alone. Finally, it is investigated that the proposed SVR-DWC configuration is superior in the aspects of both energy consumption as well as payback time. Furthermore, the SVRDWC provides a reduced complexity in compressor operation over the OVR-DWC.