Abstract
An unstable discharge rate occurs during dry fine powder discharge from a hopper because of the significant two-phase solid/gas interactions that occur in powder flows. In addition, the air bubble phenomenon may occur in a silo during fine powder discharge. In this study, we conducted experiments using a semi-conical dual-structure hopper, and examined the effects on the hopper internal flow structure, cavity fluid pressure, pressure inside the airtight cavity section, and the powder discharge rate when changes are made in the position of the supplied air injection port and the solenoid valve open/close timing. From the experimental results, it was confirmed that an appropriate pressure supply port position exists, and the change in expansion/contraction of the flexible container due to air vibration is determined by the balance between the amount of air inserted and the amount of air discharged, and does not affect the presence or absence of powder so much. Furthermore, as the pressure value in the airtight void is directly related to the change in the expansion and contraction of the flexible container, the maximum amplitude value of the pressure in the airtight void can be kept high and constant at the time of opening and closing the solenoid valve.
Highlights
In recent years, high quality, resource conservation, energy conservation, environmental protection, and hygiene have been regarded as important in the handling of powders, and there are strict requirements for precise management when handling refined powders for applications such as pharmaceuticals, magnetic powders, and pigments
The results showed that air voids appeared in the powder layer at the same time as the powder discharge, and it was confirmed that these moved inside the layer [14]
In this research, we conducted experiments using a semi-conical dualstructure hopper, and examined the effects on the hopper internal flow structure, cavity fluid pressure, pressure inside the airtight cavity section, and the powder discharge rate when changes were made in the position of the supplied air injection port and the solenoid valve open/close timing
Summary
High quality, resource conservation, energy conservation, environmental protection, and hygiene have been regarded as important in the handling of powders, and there are strict requirements for precise management when handling refined powders for applications such as pharmaceuticals, magnetic powders, and pigments. Hoppers have been used to measure and transport powders in treatment processes in industrial fields handling all sorts of powders These hoppers have the problem that arches form near the discharge port, and the powder causes a blockage inside the hopper, making it difficult to smoothly discharge powder [1–3]. Sheng et al [12] experimentally investigated the effect of air bubbles on fine powder discharge behavior, including the discharge mass flow rate and variation in the pressure inside the silo. In this research, we conducted experiments using a semi-conical dualstructure hopper, and examined the effects on the hopper internal flow structure, cavity fluid pressure, pressure inside the airtight cavity section, and the powder discharge rate when changes were made in the position of the supplied air injection port and the solenoid valve open/close timing
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