Tea dust distribution and dust removal measures during white tea finishing

【Objective】To explore spatial distribution and dynamic change law of tea dust during the process of white tea finishing,so as to provide reference for white tea cleaning and finishing.【Method】White tea finishing processes(sieving,winnowing,color sorting,electrostatic stalk-extracting,homogenization,and second drying)were taken as research objects. Collection points were set at different distances(0 and 1.2 m)from the equipment to conduct dynamic monitoring of the whole process of processing,and differences in the accumulation rate of tea dust,main dust production points,and the variation law of tea dust concentration between the finishing processes were analyzed;targeted dust removal measures such as equipment improvement,dust remover configuration were carried out,and dust removal effect after the implementation of dust removal measure was analyzed.【Result】Tea dust accumulated quickly near the round sifter,screener and dryer. Accumulation rate of tea dust near the round sifter,screener and dryer was 7.27,4.54 and 7.25 g/(m²·h)at 0 m,5.99,4.15 and 1.83 g/(m²·h)at 1.2 m. Tea dust concentration at the loading and unloading process point of the processing equipment was higher than that on the left and right sides,which were the main parts of tea dust concentration accumulation in the finishing process. In 1 h of processing,the concentration of tea dust near the processing equipment increased rapidly,and it showed a trend of increase first and then decrease in the whole process. According to test results of tea dust distribution,after taking dust removal measures such as closing the feeding port and configuring pulse dust remover,tea dust concentration decreased significantly(P<0.05). At 0 m of the round sifter,screener and dryer,PM_2.5 concentration decreased by 61.48%,49.85% and 42.03% respectively,and the PM₁₀concentration decreased by 71.66%,64.09% and54.67% respectively;PM_2.5concentration in the workshop was from 82.75 μg/m³ to 55.50 μg/m³,decreased by 32.93%,and PM₁₀ concentration increased from 247.25 μg/m³ to 136.25 μg/m³,reduced by 44.89%.【Conclusion】Round sifter,screener and dryer are the main equipment for tea dust generation during the process of white tea finishing. Taking dust removal measures such as equipment improvement and dust remover configuration can effectively control tea dust pollution in the process of white tea finishing,which can be popularized and applied in white tea enterprises' cleaner finishing.