| Summary: | 碩士 === 國立屏東科技大學 === 環境工程與科學系所 === 96 === Extensive dust may be generated in coating manufacture processes, especially at the throwing materials step which usually accounts for most of dust emission in working zones. Therefore, in order to obtain the number and mass concentrations of aerosols around the working zone during throwing materials operation, this study performed continuous sampling and monitoring at a coating plant in southern Taiwan using a micro orifice uniform deposit impactor (MOUDI), an ultra fine particle counter, and a portable dust monitor. The effects of air hood open angle, emission source distance, and throwing rate on the number and mass concentrations of coarse/fine were also investigated.
It is found that the emitted particles were mainly coarser particles during throwing materials. The >2.5 μm coarse particles and <1 μm submicron particles contributed 67 and 20% of total collected particles. At the same ventilation efficiency, increasing air hood open angle increased the collection efficiency of emission particles to decrease particle emission. At the angles of 50, 75, and 100% opening, the air hood collection efficiencies were 15.4, 36.6, 49.2, and 77.3%, respectively; When the air hood was 100% opened, its collection efficiency was 5.0, 2.1 and 1.6 times those of 25, 50 and 75% hood opening, respectively. Furthermore, the farther the distance to the throwing (emission) source, the lower the particle number concentration at the same throwing operation, ventilation efficiency, and air-hood opening. Increasing the throwing rate increased particle emission, possibly due to the decrease of particle collection efficiency.
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