乙烯精馏塔釜式中间再沸器传热计算及分析

Heat transfer calculations and analysis of ethylene fractionator side kettle reboiler

通过比较热虹吸式和釜式两种中间再沸器的特点,重点研究了釜式再沸器内循环导致的重组分聚集对传热计算,特别是对泡点、传热温差和沸腾膜系数的影响。结合热泵技术的乙烯精馏塔釜式中间再沸器,对比了侧线采出组成和釜内循环组成下的传热计算,结果表明:侧线采出组成下物料泡点比釜内循环组成下低1.76℃,在实际有效传热温差4.3℃的条件下,相应的传热温差大16.3%,即使考虑原有9.1%的设计裕量,原设计方案仍然不能满足工艺要求。提出了较为精确的釜式中间再沸器传热计算方法和建议,为乙烯精馏塔及类似精馏塔釜式中间再沸器的传热设计,尤其是小温差下的传热设计提供了参考。

By comparing the characteristics of thermosiphon and kettle side reboiler, the effects of heavy components accumulation caused by inner circulation of kettle reboiler on heat transfer are studied, especially on bubble point, heat transfer temperature difference and boiling film coefficient. Based on the ethylene fractionator side kettle reboiler combined with heat pump, the heat transfer calculation under fractionator side extraction and internal circulation fluid is compared. The results show that the bubble point of fluid in kettle rises by 1.76 ℃, and the heat transfer temperature difference calculated by fractionator side extraction is 16.3% larger than that by internal circulation fluid. The design based on fractionator side extraction can’t meet the heat transfer requirement even though the original design margin 9.1% is taken into account. A more precise calculation method and suggestion for heat transfer of circulating logistics are put forward. It provides basis for heat transfer design of ethylene distillation column and side kettle reboiler, especially under small temperature difference.