Study on thermodynamic analysis and energy saving of heat integrated distillation column

In this study, a method of using entropy to analyze the reversibility of internal thermal coupling column was proposed. Taking the ethanol water system as an example, it was proved that the energy saving of the thermal coupling column was superior to the traditional column, and the optimum operating range of the column was determined. Based on the second law of thermodynamics, the thermodynamic efficiency and the entropy increase formula of the thermal coupled column were deduced. Firstly, it was proved theoretically that the thermal coupling column was superior to the traditional column in terms of energy saving, and it was also calculated separately by the experimental data. The results showed that the operable compression ratio of the column was initially reduced to 1.8-2.6 in order to achieve better heat transfer between two columns, and the energy consumption of the overhead column was the smallest when the compression ratio was at 2.2. However, the thermal efficiency of the whole column was the highest when the range of compression ratio was 2.2-2.5. When the compression ratio is 2.5, the entropy increase of the whole column was also better than the average of the entire operating range. Thus, it was considered that the thermal coupling column had higher reversibility and better energy saving effect in this range. Taking the energy consumption, thermodynamic efficiency and entropy increase and other parameters into account, the compression ratio of 2.2 to 2.5 was the best operating range of the column. © 2019, Chemical Industry Press. All right reserved.