提升管反应器油剂间传热传质及混合特性研究

Research on heat transfer,mass transfer and mixing characteristics between oil and catalyst in riser reactor

以某炼厂180万t/a催化裂化装置提升管为模型,通过数值模拟研究了催化裂化初始原料油液雾(简称油雾)粒径对提升管反应器油剂间传热传质及混合特性的影响。结果显示,35μm油雾与70μm油雾相比,在低高度段油雾温度更低,且温度分布更加均匀;同一高度段油雾粒径越小油雾蒸发速度更快,35μm油雾达到98%蒸发量所需时间几乎是70μm油雾的一半;对于35μm油雾来说,催化剂在提升管中心的聚集效应较弱,在不同高度横截面上比70μm油雾的固含率低,且油气在横截面上分布的更加均匀,促使原料油与催化剂的均匀混合,有利于催化裂化反应,改善产品分布。

Taking the riser at a 1.8 million ton/year catalytic cracking unit in a certain refinery as a model,the numerical simulation method is employed to study the influences of initial feedstock oil mist(referred to as“oil mist”)particle size on heat transfer,mass transfer and mixing characteristics between catalyst and oil in a riser reactor for catalytic cracking.Results show that compared to 70μm oil mist,35μm oil mist has lower temperature in low section of the riser,showing a more uniform temperature distribution.In the same height range,35μm oil mist has a smaller particle size,vaporizes faster,and spends the time that reaches 98%evaporation capacity is almost half that 70μm oil mist spends.And 35μm oil mist has weaker catalyst aggregation effect at the center of the riser,lower solid holdup than 70μm oil mist in different cross section.In addition,35μm oil mist is more conductive to the distribution of oil gas,the mixing between feedstock oil and catalyst,the catalytic cracking reactions,and improving products distribution.The conclusion provides support for the design of riser reactors and nozzles.