Abstract: Isobutane alkylation catalyzed by composite ionic liquid is a new technology for the production of high quality and clean gasoline blending components. Maintaining the appropriate temperature during the alkylation reaction is crucial, and effluent cooling emerges as a pivotal measure in this regard. Currently, heat exchangers are used to cool the effluent, but there are shortcomings such as large heat exchange area requirements, high equipment cost and limited cooling effect. The presence of excess isobutane makes it possible to cool the effluent with flash spray. In order to develop a new refrigeration process for alkylated effluents, the evaporation characteristics of isobutane droplets under reduced pressure were studied. Since isobutane is a gas at room temperature and pressure, it is difficult to exist as a liquid. Therefore, a special experimental device was set up to study the evaporation process of isobutane droplets in this work. Single isobutane droplet or multiple droplets were suspended at the top of thermocouples to measure the temperature variation of each droplet, while a high-speed camera recorded the evaporation process. The effects of final pressure, ambient temperature, and droplet spacing on droplet evaporation characteristics were analyzed. The results showed that isobutane droplets underwent intense evaporation and stable evaporation phases, and the evaporation behavior of multi-droplet was similar to that of single droplet. During the stable evaporation phase, all droplets followed the classical d 2 law, and the evaporation rate of the edge and center droplets was below the single droplet. With the increase of the final pressure and the decrease of the ambient temperature, the difference between the evaporation rate of the center droplet and the single droplet gradually increased. The temperature field and vapor concentration field during droplet evaporation had a limited range of variation. When the distance between the two droplets increased to 5.48d0, the evaporation rate of the droplet gradually approached that of the single droplet.

Key words: isobutane alkylation, isobutane, droplet, depressurization, evaporation

摘要： 复合离子液体催化碳四烷基化是生产高品质清洁汽油调和组分的新技术，流出物制冷是维持其反应温度的重要过程。为了开发新的烷基化流出物制冷工艺，本工作研究了减压条件下异丁烷液滴的蒸发特性。将单个或多个异丁烷液滴悬浮在不同热电偶上，测量液滴的温度变化，同时使用高速摄像机记录其蒸发过程，考察了最终压力、环境温度和液滴间距对液滴蒸发特性的影响。结果表明，多液滴和单液滴都包含剧烈蒸发阶段和稳定蒸发阶段。在稳定蒸发阶段，所有液滴都适用d2定律，边缘和中心液滴的蒸发速率均小于单液滴。随着最终压力增加和环境温度降低，中心液滴与单液滴的蒸发速率差异逐渐增大。当两液滴的间距增加到5.48d0时，液滴的蒸发速率逐渐接近单液滴。

关键词: 碳四烷基化, 异丁烷, 液滴, 减压, 蒸发