- 學位論文
以超聲波方法鑑定內置間隔網流道內之污塞情形
Characterization of membrane fouling in spacer-filled channel using ultrasonic methods
摘要
在薄膜分離程序中，薄膜污塞一直是個重大的問題，且會依進水水質、操作 方式和前處理效果等不同而造成不同的嚴重程度。因此，藉由薄膜污塞的監控分 析來獲得分離程序中的資訊，便能提早以清洗或參數調整等找出最適化方法來減 少污塞現象的產生。 因此，本實驗利用非侵入、非破壞性的超聲波方法，並以不同頻率辨識不同 參數的污塞現象。其中，參數的選擇分別是濃度與壓力的變化，因為超聲波訊號 的偏移能得知濾餅的厚度，而振幅大小與濾餅之緻密度有關，所以此兩參數在本 研究中的變化較有明顯的效應存在；實驗的主軸是於流道內置入間隔網以改變流 體流態進而使薄膜污塞分佈產生變化，並以高頻超聲波搭配3D 馬達帶動了解污 塞的分佈狀況。 研究結果發現，低頻超聲波可以進行即時監測；而高頻超聲波因為其解析度 高，所以可測得較微小的污塞變化，且搭配馬達帶動能獲得整張薄膜的污塞資 訊，但由於能量衰減的快速，所以會造成即時監測上的困難。實驗中無倫高或低 頻的超聲波方法都能成功的區分出不同參數所造成的結果。操作濃度和壓力高者 會造成較快速的污塞現象；在流道內置間隔網的實驗中發現置入間隔網時的超聲 波能量衰減較少或是在剪應力較大的區域其能量衰減也較少，證實了高頻超聲波 系統對於薄膜過濾程序上的應用是有幫助的。
並列摘要
An ultrasonic time domain reflectometry (UTDR) technique has been used to research into the non-invasive and non-destructive study of fouling layer formation in membrane modules. However, the UTDR with transducers of various frequencies has different applications. The higher frequency transducer has higher resolution, but its energy will be easily attenuated. Purposes of this study were emphasized on understanding the fouling behaviors of empty and spacer-filled channels in membrane modules for different concentrations and operation pressures by the UTDR technique with two kinds of transducers: 5 MHz and 35 MHz individually. The experimental results showed a good correspondence between the UTDR signal responses from the membranes and the development of a fouling layer on the membrane surface. This UTDR with the 5 MHz transducer could effectively detect the one-dimensional fouling layer initiation and growth on the membrane in the membrane module in real-time. The membrane flux could be enhanced by adding spacers. The UTDR with the 35 MHz transducer and a 3D motor could be used to observe the two-dimensional fouling layer distribution on the membrane in the spacer-filled channel under the slight fouling stage even if micrometer scales. This information was not real time owing to its energy rapidly attenuated; even so it would be provided to understand where near spacers on membranes were easily fouled.