Innovene聚丙烯工艺丙烷排放方式的选择

Selection of best way for propane removal in Innovene PP plant

聚丙烯原料丙烯中不可避免地会含有质量分数约5%的丙烷,在气相聚丙烯工艺中丙烷的浓度会降低催化剂的活性。为了降低Innovene聚丙烯工艺中丙烷对催化剂活性的影响,生产过程中要不断地排除丙烷,以保持系统内丙烷浓度的稳定。通过计算获得了丙烷在气相和液相中的浓度分布,发现丙烷在液相中的含量大于其在气相中的含量,并对比分析了3套Innovene工艺聚丙烯装置丙烷脱除方式的差异。计算不同相态和不同脱除点脱除丙烷的经济性,提出了最佳的丙烷脱除方式。在顶部冷凝器出口的气、液相线上各设置一条排放线,气相排放线用于牌号切换时排出多余的氢气或乙烯;液相排放线用于不断排除反应系统中的丙烷,以维持系统内丙烷浓度稳定,提高催化剂活性,从而提高装置运行的经济效益。

As the propylene feedstock of polyproylene unit will unavoidably contain 5% of propane, the catalyst activity will be affected by propane concentration in gas-phase polypropylene process. In order to re- duce the impact of propane on catalyst activity in Innovene polypropylene process, the propane should be con- tinuously removed in the process to maintain a stable concentration of propane in the system. In this paper, the distribution of propane concentration in the gas phase and the liquid phase are acquired by calculation, and it is found that the propane in liquid phase is higher than that in gas phase. The differences in the ways of propane removal of three existing PP plants were analyzed and compared. The economics of removing propane from different phases and at different points of the plant are calculated, and the optimized way of the propane removal is recommended. A discharge line should be provided at the gas and liquid lines of the overhead con- denser respectively. The discharge line of gas is used to release excess hydrogen or ethylene during brand switching. The discharge line of liquid is operated to release the propane from the reaction system continuously to maintain a stable concentration of propane, elevate catalyst activity and improve economic benefits of unit operation.