高效率蜂巢狀平板洗滌塔

Abstract

目前對酸鹼廢氣的處理防制設備以填充濕式洗滌塔為主要方法，但此種傳統式的填充濕式洗滌塔對於低濃度、大風量之酸、鹼氣狀污染物的處理效果不佳，無法完全符合環保署法規規定要求，為了提高現行傳統式洗滌塔的去除效率，本研究設計並開發「高效率蜂巢狀平板式洗滌塔」（High-efficiency honeycomb plate-type scrubber），以改善並提升目前低濃度、大風量之酸鹼性污染物的防制設備-濕式洗滌塔設備之去除效率，將傳統式的泰勒氏拉西環（Tellerette packing）填充物改以多平行平板組合的蜂巢狀填充物取代之，同時在平板表面塗敷奈米TiO2凝膠以增加親水性，藉由此多平行板的平板蜂巢狀填充物之高比表面積及超高度親水性等特性，來提升洗滌系統的去除率。 本研究實驗將模半導體廠洗滌塔處理過後之無機酸污染氣體，由聯通管再導入本研究設計開發之高效率蜂巢狀平板式洗滌塔系統再次進行處理，以檢視此雙重洗滌塔處理之去除效率成效。當檢測之風量為1620 ，無機酸污染氣體於平板洗滌塔的滯留時間為0.5秒、循環水的pH值控制在9〜10之間等環境下，循環水量15 L/min時, 液氣比為9.26 L/min3時的條件，對HF、HCl、HNO2、HNO3及H2SO4等各種酸氣的去除效率分別為93.4%、 91.3%、91.0%、90.2%及93.3%。當循環水量由15 提高到30 時，液氣比由9.26 提昇為18.52 時，本研究開發之高效率蜂巢狀平板式洗滌塔系統去除效率分別對HF氣體可提高1.25%；對HCl氣體可提高2.53%；對HNO2氣體可提高5.63%；對HNO3氣體為5.88%；對H2SO4氣體可提高2.66%，去除效率變成97.8%、95.6%、98.6%、99.8%及98.0%，均可達到半導體製造業空氣污染管制及排放標準的95%以上。 同時檢視模光電廠實驗結果顯示，無論將廢氣於蜂巢狀平板式洗滌塔多平行板間之滯留時間延長、循環水量及液氣比提升或增加，對於將酸、鹼性廢氣採混排模式之去除效率均能符合環保署法規要求。

Packed wet scrubbers are widely used to control the emission of acid and basic gases. However, these conventional scrubbers have poor removal efficiency for high-volumetric flow rate and low-concentration acid and basic gas pollutants, which can’t meet the emission standards promulgated by the Taiwan EPA. In order to improve the performance of existing wet scrubbers, a honeycomb plate-type scrubber was designed and tested to enhance the removal efficiency of these gas pollutants. In the present scrubber, tellerettes, typical tower packings, were replaced by a honeycomb multi-parallel-plate module. The parallel plates in the module were made of polypropylene coated with nano-TiO2 particles to enhance hydrophilicity for scrubbing liquid to form uniform water film. The honeycomb module with large specific surface area and high hydrophilicity significantly enhances the removal efficiency of the present scrubber. The gas removal efficiency experiment was conducted by introducing inorganic acid gas pollutants in the exhaust gas stream from a wet scrubber in a semiconductor factory. Results show that when the gas flow rate of 1620 L/min (corresponding to the retention time of 0.5 sec ), the pH value of scrubbing liquid ranging from 9 to 10, the scrubbing liquid flow rate was 15 L/min and the liquid-to-gas ratio is 9.26 L/min3, the removal efficiency of acidic gases, HF, HCl, HNO2, HNO3 and H2SO4, are 93.4%, 91.3%, 91.0%, 90.2% and 93.3%, respectively. Results show that when the scrubbing liquid flow rate was increased from 15 to 30 L/min (corresponding to an increased in liquid-to-gas ratio from 9.26 to 18.52 L/min3), the removal efficiency for HF, HCl, HNO2, HNO3, and H2SO4 was found to increase by 1.25%, 2.53%, 5.63%, 5.88%, and 2.66%, to be 97.8%, 95.6%, 98.6%, 99.8%, and 98.0%, respectively. The removal efficiencies for these gases were also greater than 95%, which meet the emission standards for packed towers in the semiconductor factory. The removal efficiency of the present scrubber for the waste gas containing both acid and basic gas pollutants in an optoelectronic factory was also shown to meet the emission regulation by increasing the gas retention time, scrubbing liquid flow rate, and liquid-to-gas ratio.