基于射频波强化的试验型水热反应器研究

Design and Testing of Experimental Hydrothermal Reactor Based on Radio Frequency Intensification

针对水热提取反应目前主要依靠微波强化,存在穿透深度小、加热均匀性差的问题,利用加热均匀性更好的射频波为热源,基于常见的水平式平行极板射频加热系统设计了一套适用于射频强化的水热反应器。该水热反应器主要由双层反应釜、压力调节装置、光纤测温计和气动磁力搅拌器4部分构成,首先对整机结构及工作原理进行阐述,然后基于内压薄壁圆筒应力分析理论和磁力耦合传动理论对双层反应釜和气动磁力搅拌器的关键零部件进行设计,并完成了压力调节装置和测温方式的设计和选型,最后完成射频强化水热反应试验平台的搭建,并选取搅拌转速、液固比和射频极板间距对水热反应器的搅拌和升温性能进行了测试。结果表明:当液固比大于20 mL/g时,搅拌转速与对照样品纯水无显著差异(p>0.05),此时液固比不再是影响搅拌转速的主要因素;当液固比小于40 mL/g、搅拌转速大于150 r/min时,极板间距是影响物料升温速率的主要因素,随着极板间距的减小,升温速率不断加快,当极板间距为130 mm时,升温速率可达到8~10℃/min。

Since the current researches about hydrothermal extraction was mainly relying on microwave intensification,which has the problems of small penetration depth and poor heating uniformity,a method of radio frequency(RF)with better heating uniformity was used to heat and a set of hydrothermal reactor suitable for RF intensification was designed based on the horizontal parallel electrodes RF heating system.This hydrothermal reactor was mainly composed of four parts:double-layer autoclave,pressure regulator,fiber-optical thermometer and air-driven magnetic stirrer.Firstly,the overall structure and working principle were explained.Then the key components of the double-layer autoclave and air-driven magnetic stirrer were designed in detail based on the stress analysis theory of the internal pressure thin-wall cylinder and the magnetic coupling transmission theory,and the pressure regulator and fiber-optical thermometer were designed and selected,respectively.Finally,the experimental platform of RF intensify hydrothermal reaction was built and the stirring speed,liquid/solid ratio(LSR)and RF electrode gap were selected to test the stirring and heating performance of the hydrothermal reactor.The results showed that there was no significant difference for the stirring speed between the experimental groups and control group(pure water),when the LSR was greater than 20 mL/g(p>0.05),and the LSR was no longer the main factor affecting the stirring speed.When the LSR was less than 40 mL/g,and the stirring speed was greater than 150 r/min,the electrodes gaps was the main factor affecting the heating rate of sample,and the heating rate was increased continuously with the reduction of the electrodes gaps.When the electrodes gap was 130 mm,the heating rate can reach 8~10℃/min.The development of this reactor can provide important technical support for the experimental research of hydrothermal extraction based on RF intensification.