新型相变换热系统传热及流动特性

Heat transfer and flow characteristics of new phase change heat transfer system

芳烃联合装置会产生大量的低温热,抽出液塔和抽余液塔塔顶气的低温余热因取热介质泄漏问题往往未能被有效回收利用。以芳烃装置抽出液塔为研究对象,提出一种利用中间介质相变换热确保工艺本质安全的余热回收设计方案,并搭建10 kW相变换热系统实验室小型试验装置,进行相变换热系统的启动性能以及热力性能研究。实验结果表明:在相变换热系统启动过程中,随着充液率的增加,系统换热效率呈现先增加后减小的变化规律,其中最佳充液率为90%;且随着加热功率的增大,系统的启动时间减少,但减少的速率呈下降趋势。当冷却水流量及进口温度一定时,随着加热功率的增加,系统工质的工作温度、系统工质循环流量以及液位高度同步增加;当冷却水进口温度及加热功率一定时,随着冷却水流量增加,系统工质的工作温度降低,但工质循环流量和下降管液位逐渐增加。

A large amount of low temperature heat is generated in the aromatic complex.The low temperature residual heat from the top gas of the extraction tower and the extraction tower is often not recovered effectively due to the leakage of the heating medium.Taking the extraction tower of aromatics unit as the research object,a design scheme of waste heat recovery using intermediate medium phase conversion heat to ensure the intrinsic safety of the process was proposed,and a small experimental device of 10 kW phase conversion thermal system was built to study the start-up performance and thermal performance of the phase conversion thermal system.The experimental results show that with the increase of liquid filling rate,the heat transfer efficiency of the system increases first and then decreases,and the optimal liquid filling rate is 90%.With the increase of heating power,the startup time of the system decreases,but the rate of reduction is decreasing.When the cooling water flow rate and inlet temperature are constant,the working temperature of the system working medium,the circulating flow rate of the system working medium and the liquid level height increase synchronously with the increase of heating power.When the inlet temperature and heating power of the cooling water are constant,the working temperature of the system working medium decreases with the increase of the cooling water flow,but the circulating flow rate of the working medium and the liquid level of the downcomer gradually increase.