Abstract: Aiming at the problem of catalyst and adsorbent failure caused by the leakage of heat taking medium in the tower top low-temperature heat recovery process of aromatics combined unit, a heat taking scheme of phase change heat exchange of intermediate working medium is proposed to ensure the intrinsic safety of the process. Aspen HYSYS and EDR are used to establish the steady-state numerical model for the whole process simulation of the aromatic low-temperature heat recovery phase change heat exchange system under the field working condition of 100 kW. The reliability of the steady-state numerical model is verified by the combination of experiment and numerical simulation. The influence of process and structural parameters on the thermal characteristics of the system is studied. The results show that with the increase of the inlet temperature of demineralized water, the system heat load, circulating work quality and liquid level height of the system gradually decrease, and the working temperature increases gradually. With the increase of overhead gas flow, the system heat load and working temperature first increase and then decrease, the circulating work quality and liquid level height first decrease and then increase, and the lower the inlet temperature of demineralized water, the greater the critical flow value. With the increase of demineralized water flow, the system heat load, circulating work quality and liquid level height gradually increase, and the working temperature gradually decreases. In case of large temperature difference and large flow of demineralized water, in order to avoid the restriction of system heat transfer performance by driving force, it is necessary to ensure that the installation height is not less than the liquid level difference. The system heat load increases gradually with the increase of the rising pipe diameter, and basically unchanged after the pipe diameter is greater than Φ159 mm. In the case of "cut-off", the system heat load decreases gradually with the increase of installation height. In fact, the installation height does not need to be increased too much; The heat exchange of the system with horizontal (reboiler) and horizontal (condenser) combination is about 3% greater than that of horizontal (reboiler) and vertical (condenser) combination.