Research and application of bag filter system for railway ballast bed coal suction vehicles: An optimization and application study.

The current bag filter system used by railway ballast bed coal suction vehicles for cleaning coal dust from railway tunnels has low operational efficiency and generates significant volumes of dust. This paper describes a simulation test unit designed to enhance the dust removal performance in railway tunnels. The flow field inside the simulation test unit is investigated under different operating conditions through numerical simulations, and the variations in air volume and working resistance, total dust collection efficiency, and optimal operating parameters of a pulse cleaning system are identified through a series of experiments. The numerical results show that the pulse cleaning system does not significantly affect the uniformity of the flow field distribution at the bottom of the filter cartridge during the process of operation. The experimental research indicates that the simulation test unit satisfies the design requirements, achieving an average total dust removal efficiency of 99.93%. A field application shows that the total dust mass concentration at the operator position can be reduced from 335.8 mg∙m-3 to 4.2 mg∙m-3, effectively improving the operating environment within the tunnel.

Experimental study on the atomization characteristics and dust removal efficiency of a fan-shaped nozzle for purifying working environment.

The inadequacy of the existing research in characterizing the atomization performance of the whole atomization field by the local region at nozzle axis hinders the improvement of dust removal performance of a spray system, especially for fan-shaped nozzles with large atomization angle. To solve this inadequacy, 88 measuring points were designed in this study to reveal the spatial distribution characteristics of atomization parameters of a fan-shaped pressure atomization nozzle using a 3D Fiber Phase-Doppler Anemometer. Moreover, the atomization performance and dust removal performance of the whole atomization field under different spray pressures were characterized. The results showed that the spatial distribution of atomization parameters in the axis and radial direction of the nozzle was inhomogeneous. As the axial distance from the nozzle outlet increased, the average droplet size showed a trend of first decreasing and then increasing, the proportion of the droplet of 15-70 µm showed a trend of first increasing and then decreasing, while the average droplet velocity and droplet flux showed a decreasing trend. In addition, the spray orientation was perpendicular to gravity, and the atomization field was parallel to gravity, resulting in a significant difference in the average droplet size between the upper region and the axis. Compared with the upper and lower regions, the atomization effect at the axis was superior, manifested by higher average droplet velocity and droplet flux, indicating that characterizing nozzle atomization performance with atomization parameters at the axis will lead to overestimation. The increase of spray pressure can improve atomization performance and dust removal efficiency to a certain extent, but the improvement effect had a limit. The atomization field can be divided into atomization region, expansion region and contraction region, and the expansion region was considered as an effective dust removal region. These findings provide reference for the design and operation of a spray system.