基于射流反馈振荡原理的被动式强湍动液液萃取器

A large amount of spent fuel needed to be processed with Purex reprocessing technology to recover Uranium and Plutonium were produced from nuclear power plants developed at the highest possible speed in China. Up to now no perfect liquid-liquid extractors available under ridioactive environment exit for Purex technology, which restricts establishing large-scale spent fuel reprocessing plants and development of nuclear power in China. An original extractor is proposed in the application based on analysis on pulsed extraction columns and centrifugal extractors now adopted in Purex technology. The extractor is designed based on the passive mixing idea, only taking advantages of hydrodynamics such as The Coanda effect, fluidic oscillation and fluidic entrainment. Strong turbulence mixing between the organic phase and the water phase is accomplished in the extractors without any moving parts. The hydromechanical characteristics and mass transfer performance of the extractors as the flow field transient characteristics and concentration field distribution are investigated by the factor experiments, the computational fluid dynamics simulation (CFD), the planar laser induced fluorescence method (PLIF) and the extracting performance experiments. The application can propose a novel method for designing liquid-liquid extractors used in the Purex process and establish a basis for the next generation Purex technology.

我国核电事业的高速发展产生了大量需要通过Purex后处理工艺进行铀、钚等有用元素回收的乏燃料，但在放射性环境下，目前仍没有一种液液萃取设备能够完全满足要求，这成为我国建立大型乏燃料后处理厂的瓶颈问题,严重制约了我国核电事业的发展。本项目通过对Purex流程中的现有液液萃取设备优缺点的分析，提出了一个放射性环境下的液液萃取设备研究的新思路：立足于被动式混合概念，基于流道设计，利用流体本身的动力学特征- - Coanda效应、射流反馈振荡、射流卷吸作用，在无机械可动部件的情况下实现两相的强湍动混合。本项目通过因素影响实验、计算流体力学模拟、面激光诱导荧光技术、两相萃取实验等方法对该新型Purex流程液液萃取器的单级和多级结构的流场瞬态特征、浓度场分布规律等水力学特征和传质性能进行研究。本项目工作可为我国Purex流程中的液液萃取设备的研究提供一种新思路并为下一代Purex工艺开发奠定基础。

我国核电事业的高速发展产生了大量需要通过Purex后处理工艺进行铀、钚等有用元素回收的乏燃料，但在放射性环境下，目前仍没有一种液液萃取设备能够完全满足要求。针对该背景，本项目立足于被动式混合概念，提出了一种新颖的萃取器——基于Coanda效应的被动式反馈振荡微萃取器。本项目通过因素影响实验、流场显微示踪、计算流体力学模拟、萃取实验等方法对该新型萃取器的单级和多级结构的水力学特征和传质性能进行了研究。主要结果包括：（1）流型：随着雷诺数的增加，平行层流、内部循环流和反馈振荡流依次出现，其中内部循环流和反馈振荡流能显著增强两相混合性能；（2）结构优化：振荡腔内带有分流体且反馈管非对称的结构具有最好的混合性能；（3）混合机理：通过CFD模拟，通过粒子轨迹追踪、庞加莱映射等方法证明被动式反馈振荡微萃取器在反馈振荡发生后能够通过混沌对流实现高效混合；（4）萃取性能：通过单级和多级萃取实验，证明该新型萃取器具有很好的萃取性能，且随着雷诺数的提高，停留时间越短萃取性能反而越高，在典型条件和萃取体系中，在0.018s左右即可在单级中实现萃取平衡。本项目工作可为我国Purex流程中的液液萃取设备的研究提供一种新思路并为下一代Purex工艺开发奠定基础。