基于吸收式热泵的精馏塔用能系统优化研究

受环境温度限制,加压精馏塔操作压力的设定值普遍偏高,系统能耗较高。以某脱丙烷塔为例,将操作压力由2.00 MPa降至1.60 MPa,塔底重沸器加热负荷可降低12.9%,若能继续降低操作压力,则可以进一步降低系统能耗。采用"基于第一类吸收式热泵的精馏塔物料梯级加热方法",提高塔顶冷却能力,降低塔顶冷凝器工作温度,进而有效降低脱丙烷塔的操作压力至1.30 MPa;同时利用吸收式热泵回收塔顶馏出物冷凝热来对进料预热,替代部分重沸器消耗的工艺蒸汽,通过对操作参数及吸收式热泵配置的优化,可使脱丙烷塔能效提高23.3%。将富余的吸收式热泵制热水作为脱乙烷塔和精丙烯塔两塔重沸器热源,可显著降低气体分馏装置的蒸汽消耗量,经济效益显著。

OPTIMIZATION STUDY FOR ENERGY CONSUMPTION OF DISTILLATION COLUMN BASED ON ABSORPTION HEAT PUMP

Limited by the environmental temperature, the operating pressure of the pressurized distillation column is generally higher, and the energy consumption is increased. Taking depropanizing column as an example, if the operating pressure drops from 2.00 MPa to 1.60 MPa, the heat duty of reboiler can reduce by 12.9%. If the operating pressure drops further, it could saves more energy. By using “the cascade heating method for feed of distillation column based on absorption heat pump”, the cooling capacity of the condenser is improved and the temperature of the condenser at gas outlet of the distillation column can be reduced, resulting in lower pressure of 1.30 MPa. At the same time, the waste heat recovered from the gas outlet material is used to preheat the feed instead of steam from the reboiler. The system energy consumption can reduce by 23.3% through the optimization of the new system. On the other hand, the hot water produced by the absorption heat pump can be used as the heat source for the deethanizing column and propylene rectification column, so the waste heat recovery efficiency of the system is obvious.