Ultrasonic-based particle measurement is developing rapidly, but no research has been conducted on the measurement of ore particles inside multilayer flexible pipes. In this paper, based on theoretical analysis and simulation, the measurement of ore particles inside multilayer flexible pipes is investigated. Based on various attenuation models, the ECAH model, UA model, HT model and BLBL model are compared, and the ultrasonic attenuation mechanisms at different frequencies, particle sizes and concentrations are analyzed. The multilayer model was established by COMSOL Multiphysics to obtain the attenuation coefficients of ultrasonic waves in multilayer pipes, and the particle size and concentration of ore particles were obtained by inversion of the particle size using the regularization method. The results show that the BLBL model is applicable to the inversion of the particle size and concentration of ore particles by ultrasonic attenuation method.
Deep-sea mineral resources are abundant and have high development value. Hydraulic lifting is the most practical and potential way of ore transportation at present. In the transmission of ore in multi-layer flexible pipelines, real-time monitoring of ore particle concentration is one of the technologies that need to be solved in the design of deep-sea mining systems. Typical phase holdup measurement methods include: Optical Technique, Conductivity Technique, X-ray Technique, etc. However, each of these methods has its own drawbacks, for example, optical-based methods require fluid transparency, conductivity-based methods require the measured object to be magnetic, and x-ray technology-based methods are not only expensive but also harmful to the environment and human body (Chaouki et al., 1997). Compared to the above methods, ultrasonic methods have the advantages of being more penetrating, non-invasive, can provide real-time information, and have a wide measurement range (Povey, 2000). This means that ultrasonic techniques can measure high concentration suspensions as well as various particle size concentrations, and the ultrasonic system is simple and stable and can provide real-time measurement information, and in general, ultrasonic techniques are very suitable for two-phase flow measurements (Murai et al., 2010).
