Energy-saving technology of styrene unit based on mechanical vapor recompression coupled with organic Rankine cycle process

The conventional four columns styrene distillation unit for separating benzene, toluene and ethylbenzene etc. required high energy consumption. Numerical simulations were performed by Aspen Plus software(version 7.3) environment under the Peng-Rob thermodynamic model. In order to improve the energetic efficiency, the multi-effect distillation (MED), mechanical vapor recompression (MVR) heat pump technology and organic Rankine cycle (ORC) generation power technology were suggested as competitive improvements on conventional distillation process. The economy of the double-effect distillation (DED) process was performed and the MVR heat pump distillation process was compared based on total annual cost (TAC). To further protect the environment friendly, the MVR heat pump distillation process coupled with ORC generation power technology was developed. The results show that compared with the conventional four columns distillation process, the DED process, MVR heat pump process, and MVR heat pump process coupled with ORC generation power technology can reduce energy by 21.3%, 40.3%, and 50.5%, save TAC by 19.4%, 37.3%, and 41.0% respectively. In all examples, the MVR heat pump distillation process coupled with ORC methodology is able to outperform previous studies regarding TAC, proving a practicable alternative to methods that are currently applied in the literature.