The condensing evaporator is the core heat exchange equipment of the distillation system in the air separation unit, connecting the lower and upper towers of the air separation unit, and has dual functions of condensation and evaporation. It is a key component to ensure the stable operation of the double tower distillation and achieve air oxygen nitrogen separation.
This device relies on the pressure difference between the upper and lower towers to form a temperature difference, achieving internal self-sufficient heat exchange without the need for external heat and cold sources. On the one hand, high-pressure saturated nitrogen gas flows through the heat exchange channel at the top of the lower tower, releasing latent heat of vaporization and condensing to produce liquid nitrogen. Part of the liquid nitrogen refluxes to the top of the lower tower, providing reflux liquid for distillation in the lower tower; The other part of liquid nitrogen is throttled and sent to the top of the upper tower to ensure stable distillation conditions.
On the other hand, the low-pressure liquid oxygen at the bottom of the upper tower absorbs the heat released by the condensation of nitrogen and continues to evaporate and vaporize into oxygen. Part of the generated oxygen is used as rising steam to participate in gas-liquid heat and mass transfer in the upper tower, completing the deep separation of oxygen and nitrogen; The other part serves as a finished oxygen delivery device to meet the gas demand for production.
In addition, the condenser evaporator also plays a role in balancing the cold and hot loads of the device, stabilizing the pressure difference between the two towers, and regulating the liquid oxygen level in the upper tower. At the same time, stable evaporation conditions can avoid faults such as dry evaporation of liquid oxygen and heat exchange failure, reduce the risk of hydrocarbon accumulation, and ensure the safe, efficient, and continuous operation of air separation equipment. It is an indispensable energy exchange hub for the entire air separation unit.
