氧化铝管式降膜蒸发器的分析

Exergy Analysis of Tube Falling-Film Evaporator in Alumina Production Process

在热力学参数、焓和熵的基础上,分析了焓分析法和分析法的联系和差异。通过对蒸发器的热力学分析,提出了确定内部损的方法,建立了蒸发器的分析模型。通过对一氧化铝厂四效蒸发系统各蒸发器进行分析,利用所提出的方法和推导的公式对各蒸发器的内部损、效率和损率进行计算,找到了蒸发器损失的主要原因,得出了降低传热温差引起的损失是提高蒸发效率的主要途径。流阻损也是不容忽视的,可通过减小蒸发器内蒸汽侧的流动速度和定期清理蒸发器结垢来减少流阻损。

The connection and difference between enthalpy analysis method and exergy analysis method are analyzed based on exergy,enthalpy and entropy.By the thermodynamic analysis on evaporator,a method to determine the internal exergy loss is proposed and the exergy analysis model of evaporator is established.Through the exergy analysis of each evaporator of four-effect evaporation system of an alumina plant,the internal exergy loss,exergy efficiency and exergy loss rate can be calculated by using the method proposed and the equations derived.The main cause of the exergy loss is found out,and the main method to improve the evaporation efficiency is obtained to reduce the exergy loss that caused by heat transfer temperature difference.The exergy loss caused by flow resistance should also be paid attention to,which can be reduced by reducing the flow velocity of steam in a evaporator and cleaning of scabbing in evaporator regularly.