内部热耦合塔的热力学分析和节能研究

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

提出了一种运用熵法对内部热耦合塔可逆性进行分析的方法。以乙醇-水体系为例证明了热耦合塔相比于传统塔较优的节能优势,并确定了该塔的最佳操作范围。本文根据热力学第二定律,对热耦合塔的热力学效率以及熵增的公式进行推导,从理论上证明了热耦合塔在节能方面优于传统塔,又结合实验数据分别对其进行了详细计算。结果表明:为实现两塔段间较优的传热推动力,将该塔的可操作压缩比初步缩小到1.8～2.6;压缩比为2.2时塔顶塔釜能耗最低;压缩比为2.5时,全塔热力学效率最高;操作压缩比操作范围在2.2～2.5时,全塔的熵增优于全部操作范围内的平均值,认为在该范围内热耦合塔的可逆性更高,节能效果更优。综合考虑能耗、热力学效率及熵增等各项参数,压缩比2.2～2.5为该塔的最佳操作范围。

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.