Multi sensor suite comprising active and passive ultrasonic transducers for monitoring solids flow and silo integrity

Abstract

The bulk solid flow in silos and monitoring silo integrity are still challenging problems in the field of powder science and technology. The types of flow in silos have to be identified as early as possible to remedy problems associated with rat-hole, arching and plug flow to facilitate the preferred mode of mass flow. Acoustic techniques have been used to solve some of these issues with some success in the recent past. By incorporating passive ultrasonic sensors mostly in the form of acoustic emission sensors, in addition to active ones used in interrogating surface and flow of solids in silos, silo inlets and outlets, it has been shown that the solids flow in silos can be identified without interrupting the process thus leading to improved process monitoring and control in the storing, transport and handling of bulk solids. A sensor suite comprising multiple passive and active ultrasonic sensors have been used successfully in achieving the following in a pilot plant consisting of silos with multiple hoppers and associated transport facilities: identification of solids flow type, identification of particulate material from signature signals from passive sensors, solids flow rate, slip velocity and assessing silo integrity. Assessing silo integrity is important in large scale silos in avoiding catastrophic accidents in plants dealing with bulk solids. The sensor data fusion is done in both frequency and time domains using AI-methodologies involving multivariate data analysis.