濕式靜電旋風集塵器實場測試研究‏

Abstract

乾式靜電集塵器具有低操作壓損及高處理效率之優點，使其廣泛地被工業界所使用。然而該設備也有以下缺點，如使用上易發生粉塵餅堆積，進而導致處理效率降低、粉塵再揚起、背電暈及無法連續性操作等問題。 為改善上述問題，本研究設計一個濕式靜電旋風集塵器(wet electrostatic cyclone)，本集塵器主要由旋風器、放電電極和循環水槽組成。當粉塵進入本集塵器後，旋風器會先將粒徑大於1 μm之微粒去除，再由放電電極產生的電暈對微粒進行充電，讓微粒移動至低電位區(旋風器內壁為本設備接地端，故電位為0 V)，再由壁面上均勻水膜將微粒帶至循環水槽中，以去除1 μm以下之微粒。 完成本集塵器設計後，即用Al2O3油酸(OA)及碳煙(Soot)進行測試，結果顯示風量在1000 L/min時的去除效率在97 ~ 99 %之間，風量在2500 L/min時的去除效率在88~95 %之間；風量在4500 L/min時的去除效率在78~92 %之間。 於半導體廠實場測試結果顯示，當集塵器操作電壓為-18 KVdc電流為4.8 mA，在連續操作26天下仍然可以對質量中間粒徑(mass median aerodynamic diameter, MMAD)為220 nm、質量濃度為20 – 50 mg/m3的酸排放微粒維持90%以上的去除效率。實驗結束開啟設備進行檢視，收集壁面可持續保持清潔，本表示本集塵不會有粉塵餅堆積、粉塵再揚起的問題，且具有連續操作的功能。

Dry electrostatic precipitators (ESP) have been widely used to remove particles emitted from industrial processes for its advantage of low pressure drop and high collection efficiency. However, some disadvantages also exist including, for example, accumulated dust cakes on the discharge and collection electrodes resulting in problems of reduction of the collection efficiency, particle re-entrainment, back corona and discontinuous operation, etc. In order to solve the problems associated with the traditional dry ESPs, a wet electrocyclone mainly consisting of a cyclone, discharge electrodes and circulation water channels was developed. The dust flow is first drawn into the device, after which the cyclone is used to segregate particles larger than 1 μm and then discharge electrodes with generated corona are used to charge particles. The charged particles of less than 1 μm are then moved to the low-potential zone ( the inner wall of the cyclone is the grounding end of the device, thus with 0 V electric potential), subsequently carried to the circulation water channel by scrubbing water uniformly filmed onto the wall. After the design of the wet electrocyclone, Al2O3, oil acid and soot are chosen for validation test, the results of which show that the particle collection efficiency ranged from 97~99%, 88~95 % and 78~92 % at the dust flow rate of 1000, 2500 and 4500 L/min, respectively. Field test results in a semiconductor industry showed that the present wet electrocyclone can be operated continuously for 26 days at collection efficiency of higher than 90% to control acid particles with mass median aerodynamic diameter (MMAD) of 22nm and mass concentration ranged from 20~50 mg/m3, when the operation voltage and current are 4.3 kV and 4.8 mA, respectively. The collection wall was checked to be clean after experiments, indicating that no dust cake deposition and particle re-entrainment exist and continuous operation could be achieved.