常压塔顶冷凝系统水露点预测

Prediction of Water Dew Point in the Overhead Condensing System of Crude Atmospheric Distillation Unit

以常压塔塔顶石脑油的相对密度和蒸馏数据为基础,通过化工流程模拟软件Aspen Plus生成了一系列虚拟组分,计算了每个虚拟组分的摩尔分数、标准沸点、相对密度和相对分子质量,并估算了每个虚拟组分的临界性质和偏心因子。使用Peng-Robinson方程对常压塔塔顶油气馏分进行严格三相平衡计算,研究了烃-水之间的二元交互作用参数对水在烃相的溶解度及水露点的影响。假设塔顶油气体系形成的水相为游离水,研究了水在烃相的溶解度对水露点的影响。计算结果表明,烃-水之间的二元交互作用参数对水在烃相的溶解度影响非常显著,当交互作用参数取0.43时,计算的水的溶解度与API Data Book计算值一致。使用2种方法计算时,水在烃相的溶解度对水露点的影响均不明显。使用严格的三相平衡计算的水露点为384.65K,比基于游离水假设计算的水露点高1.3K。

On the basis of the relative density and distillation data of naphtha,a series of pseudocomponents were yielded by Aspen Plus.The normal boiling point,relative density,relative molecular mass and mole fraction of each pseudo-component were calculated,and the critical properties and acentric factor were estimated by using the corresponding correlation equations with Aspen Plus.With the use of Peng-Robinson equation of state,rigorous three phase equilibrium calculation on gaseous oil fraction of crude atmospheric distillation column overhead system was implemented and the effects of the binary interaction parameters（BIPs）between hydrocarbon and water on water dew point（WDP）and the solubility of water in the hydrocarbon phase were studied.Assuming that the formed water phase of overhead gaseous oil system was free water,the effects of the BIPs between hydrocarbon and water on WDP were researched.The results showed that the BIPs between hydrocarbon and water have great influence on the solubility of water in the hydrocarbon phase. When the BIP was 0.43,the calculated solubility of water was in great agreement with the calculated value by API data book.The solubility of water in the hydrocarbon phase has little influence on WDP.The WDP by rigorous three phase equilibrium calculation was384.65 K,1.3Khigher than the computed result based on free water assumption.