Abstract: Measuring multiphase flow parameters and the understanding of multiphase flow mechanisms are of great importance value for the design, operation, and optimization of industrial process devices. Due to the inherent multiscale nature of multiphase flow, its flow field often has great complexity, which makes our understanding of its flow process relatively limited. There are still many key issues that need to be explored in the mechanism of multiphase flow. Positron emission particle tracing (PEPT) is a new undisturbed and non-destructive imaging method for complex multiphase flows in industrial processes. γ photon detection is used to perform 3D dynamic imaging of radioactive labeled tracer particles. Due to γ photons have high penetration and are not affected by electromagnetic fields, making PEPT a unique advantage in detecting non-transparent and complex industrial multiphase flows. Currently, it is mainly used for measuring multiphase flow phenomena and extracting system physical parameters in industrial fields such as chemical, food, and pharmaceutical industries. However, the difficulties in preparing miniaturized tracer particles and the poor localization effect of multiple tracer particles at the same time seriously hinder the further application and promotion of PEPT technology. In this work, basic principles of PEPT technology are firstly briefly introduced, then the key technologies and research progress of PEPT are discussed from the aspects of tracer particles, algorithms, hardware systems and data processing in applications. The existing problems and potential development directions are pointed out. Finally, the development and application of PEPT is summarized and prospected.

Key words: multiphase flow, non-destructive testing, positron emission particle tracing, tracer particles, γ photon detection, locating algorithm

摘要： 多相流参数检测对工业过程装置的设计和优化至关重要，但其多尺度与内在复杂性限制了对多相流动过程的理解，在流动机制方面仍有许多关键问题尚未明晰。正电子发射粒子示踪(PEPT)是一种面向工业过程中复杂多相流的新型无扰、无损的核成像方法，利用γ光子探测对放射性标记的示踪颗粒进行三维动力学成像。由于γ光子具有高穿透性、不受电磁场影响等特点，使得PEPT在非透明复杂多相流检测上具有独特优势。目前主要应用于化工、食品、制药等工业领域内多相流动现象的测量和系统物理参数提取。然而，小型化示踪颗粒制备困难、多个示踪颗粒同时定位效果差等问题严重阻碍了PEPT技术的进一步应用和推广。本工作首先介绍了PEPT技术的基本原理；然后重点从示踪颗粒、算法、硬件系统、数据处理及应用等方面讨论了PEPT关键技术及其研究进展，并指出其中存在的问题和潜在的发展方向；最后，对PEPT技术的发展和应用进行总结和展望。

关键词: 多相流, 无损检测, 正电子发射粒子示踪, 示踪颗粒, γ光子探测, 定位算法