創新不銹鋼濾網於油霧過濾之研究 -慣性衝擊器及多層高壓不鏽鋼靜電濾材之開發

Abstract

空氣中的懸浮微粒(Particulate matter, PM)是亞洲空氣汙染中一個重要的問題，聯合國國際癌症研究署 (International Agency for Research on Cancer)也將其列為第一級致癌物，而根據台灣行政院環保署建立之空氣污染排放總量資料庫清冊系統(TEDS 9.0; Taiwan Emission Data System 9.0)指出台灣在2013年餐飲業排放油霧占總PM2.5整年排放量之6.39%，而針對台灣不吸菸之家庭主婦，如果長期處於因高溫烹飪所產生之油霧環境下，會增加其罹患肺癌3.2％至12.2％的風險比率，因此如何有效控制油霧之問題十分重要。然而在市場上廣泛使用之纖維濾材在負載油霧後壓降會急遽提升，導致使用一段時間即需更換，為了延長纖維濾材之使用壽命，本文利用慣性收集板、大孔徑之不鏽鋼濾網等在過濾油霧時較不會發生阻塞或壓降急遽提升之過濾器，並利用通以高電壓之方法在不鏽鋼濾網間產生電場，收集空氣中之帶電微粒。 本研究在慣性收集板上設計導油道，將過濾後的油滴聚集並排出，在過濾流速45 cm/s下能過濾氣膠粒徑6 μm以上之油霧微粒達50%，並利用在不鏽鋼濾網上通以高電壓之方式，收集小於6 μm之油霧微粒。以通高壓電之不鏽鋼濾網與接地不鏽鋼濾交叉排列，並在濾網間產生電場收集油霧，此時電場大小、交叉排列層數、過濾流速與濾網結構皆為影響過濾效率之重要參數。本研究最終使用具有1.4 kV/mm電場的正電與接地交叉排列之27層100目不鏽鋼濾網，在過濾流速為15 cm/s時，對電移動度粒徑大於50 nm之微粒有50%以上之過濾效率，對電移動度粒徑大於120 nm之微粒有70%以上之過濾效率，能有效的降低後端纖維濾材之油霧負載量，延長使用壽命，且所收集之油霧可自動收集，不需進行不鏽鋼濾網更換。

Fine particulate matter (PM2.5) is a critical and imperative problem in Asia. It has been classified as the 1A carcinogen by The United Nations International Agency for Research on Cancer (IARC). According to the latest TEDS 9.0 (Taiwan Emission Data System 9.0), it shows that oil mist emissions from restaurants account for 6.39% of the total PM2.5 emissions in 2013. This ratio is even higher than power supply industries that only contributes 3.64％ of total emission. For housewives who do not smoke in Taiwan, their risk to develop lung cancer can increase by 3.2% to 12.2% through a long term exposure of oil mist at high temperature. Therefore, an effectively control to oil mist emissions is a very important task nowadays However, common commercial fiber-based filters can be quickly masked by oil mist and are needed to be replaced frequently. In order to prolong the lifetime of the fiber filter, an inertial impactor plate and stainless steel mesh filter are used in this paper. They are less likely to clog when filtering oil mist and oils can be directed for collection by design of oil trenches. Furthermore, a high voltage stainless steel mesh array with a high electric field are also introduced to collect charged particles in the air for long term usage. For the impactor developed in this study, liquid channels are designed in the inertial impactor plate, and the filtered oil droplets are collected and drained in the channel. At the flow rate of 45 cm/s, the oil mist with aerodynamic diameter larger than 6 μm can be filtered. For the particles smaller than aerodynamic diameter of 6 μm can be captured by the multi-layered high-voltage electrostatic mesh filter. A high electric field is applied to the multi-layered mesh filter for improving filtration efficiency. Parameters include the electric field, the number of filter layers, the filtration flow rate and the filter structure. Finally, we developed a 27-layer 100-mesh stainless steel filter driven under 1.4 kV/mm electric field with the optimal performance. At a filtration flow rate of 15 cm/s, the filtration efficiency of particles with particle size larger than 50 nm is above 50%, and the filtration of particles with particle size larger than 120 nm reached 70%. This method provides means to reduce the oil mist loading on the back fiber filter and prolong its lifetime for long term usage.