Abstract

Microwave has been widely used in pyrolysis of waste lubricating oil, but the uneven electromagnetic field distribution seriously affects the product distribution and even aggravates coking in pyrolysis process, where the pyrolizer structure plays a dominant role. Four structures were simulated in the continuous pyrolysis of waste lubricating oil under microwave irradiation, including single circular tube, parallel tubes, pulse type spherical tube as well as circular tube equipped with baffles. The temperature distribution and pressure drop were calculated to evaluate the performance of heat transfer and flow behavior. The simulation indicates that there exists several “hot spots” in continuous circular structure due to the maldistribution of electromagnetic field, which may cause coke in industry. The baffles can enhance the turbulence of oil flow in the reactor but cause several stagnant zones, which hinder local liquid renewal. The parallel tube-type pyrolizer shows highly efficient heating performance but large temperature difference among each tube as well as large pressure drop due to the decrease of effective flow area for high viscous oil. Among those structures, the spherical tube can accelerate the renewal process of liquid and thus make the temperature more uniform, which is a durable and available strategy for microwave-inductive pyrolysis.

摘要

微波已广泛应用于废润滑油的热解，但电磁场分布不均严重影响产物分布，甚至加剧热解过程中的结焦，其中热解器结构起主导作用。模拟了微波辐射下废润滑油连续热解的四种结构，包括单圆管、平行管、脉冲式球管和带挡板的圆管。计算温度分布和压降以评估传热和流动行为的性能。仿真表明，由于电磁场分布不均，连续圆形结构中存在多个“热点”，可能导致工业结焦。挡板可以增强反应器中油流的湍流，但会导致多个停滞区，从而阻碍局部液体更新。平行管式热解器加热效率高，但管间温差大，高粘度油的有效流通面积减小，压降大。在这些结构中，球形管可以加速液体的更新过程，从而使温度更加均匀，是微波感应热解的一种持久可行的策略。平行管式热解器加热效率高，但管间温差大，高粘度油的有效流通面积减小，压降大。在这些结构中，球形管可以加速液体的更新过程，从而使温度更加均匀，是微波感应热解的一种持久可行的策略。平行管式热解器加热效率高，但管间温差大，高粘度油的有效流通面积减小，压降大。在这些结构中，球形管可以加速液体的更新过程，从而使温度更加均匀，是微波感应热解的一种持久可行的策略。