以Na2SO3去除NO2之洗滌塔的效率研究-以太陽能Cell電池廠為例

Abstract

摘 要 太陽能電池業的粗糙化製程，使用了硝酸來蝕刻矽晶片，矽晶片與硝酸反應後生成了NO2氣狀污染物，類似黃色的NO2廢氣經製程酸排氣系統的煙道排放至大氣中，濃度約在55ppm，致使煙道出口排放出大量黃色煙霧的氣狀污染物，這是太陽能Cell工廠設廠前並未預期到的問題。由於NO2對人體的危害有一定的影響，且屬於空氣污染防制法規中的管制排放物種。本研究主要設計1台處理風量為100 m3/hr r的濕式填充洗滌塔作為NO2的削減去除設備，並以實際製程中所排放的NO2做為試驗氣體，濃度範圍在41~51ppm，濕式填充洗滌塔則添加Na2SO3作為去除NO2的吸收洗滌液，探討Na2SO3洗滌液對於NO2的去除效率，並改變氣體與液體接觸時間、液氣比(L/G)、Na2SO3吸收劑在水中的莫耳濃度等参數，經實驗結果顯示，濕式填充式洗滌塔內之循環水含Na2SO3濃度達0.3M、液氣比(L/G)等於5倍、洗滌液與NO2接觸時間達3秒時，其NO2最高吸收去除效率可達95%以上，另在實驗中亦發現，NO2濃度大於30ppm以上時則會有黃煙產生，當煙道排放的NO2濃度低於30ppm以下時，即不會有黃煙產生。

ABSTRACT Currently, the increase of photovoltaic cell manufacturers threatens the environment in Taiwan with NO2 pollution. This paper presents an experimental study of the absorption of NO2 in a wet scrubber with a Na2SO3 aqueous solution. Experiments have been conducted to determine the effects of various operating parameters such as inlet concentration of the Na2SO¬3 solution, liquid-to-gas ratio, NO2 removal efficiencies, and Ph value. The experimental device used in this study was a rectangular scrubber 2.84 m in height with a constant 100 m3/hr gas rate of NO2 input. The experimental results showed that the removal effectiveness of NO2 increased while increasing the concentration of the Na2SO¬3 solution, contact time, and the L/G ratio. In addition, when the L/G ratio was equal to 5, with 0.3 mole of Na2SO¬3 solution and a contact time of 3 seconds of L/G, the removal efficiencies are higher than 95 %.