The Effects of Aqua Regia on the Performance of Wet Scrubbers in Color Filter Process

• Main Authors: Chia-yi Lee, 李佳依
• Other Authors: Moo-Been Chang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/97906835501121730283

碩士 === 國立中央大學 === 環境工程研究所碩士在職專班 === 100 === Photonics products roll out of production lines every day, and color filter is a key component of TFT-LCD, accounting for more than 20% of total manufacture cost. In response to market demands, new products are being developed and innovative production processes are introduced. However, introduction of new chemical materials often comes with new processes which inevitably affect processing efficiency of existing facility such as air and water pollution control equipment. With the pressure of reducing production costs, the costs to keep pollution control equipment running are not always the top priority of manufacturers. These firms often establish the systems to meet the minimum standards set by government. The subject of this study is pertaining to the new PVA process in which aqua regia is used for etching. Aqua regia is a powerful acid that contains hydrochloric acid which is an air pollutant regulated by Taiwan EPA. This will definitely have a profound impact on the operation of existing air pollution control equipment. The cost analysis was carried out with the consideration of energy and material consumption, and the result was compared with the value of unit product and the quantity of air pollutants removed. A comparison of processing efficiency before and after change of production process was performed with the air pollutant emission testing as an attempt to understand the extent of influence of aqua regia on the existing air pollution control equipment. Data of actual operations were compiled for comparison and to investigate the difference in real operations and possible room for improvement. It was learned that the white smoke generated during the aqua regia process was effectively controlled by increasing the conductivity to 150 ms/cm or more, and the removal efficiency of hydrochloric acid was 58.3% before the introduction of aqua regia. After the introduction of aqua regia, the efficiency reached 93.1% as the inlet hydrochloric acid concentration increased. However, the removal efficiencies of chlorine and nitric acid were less than 85% due to low inlet concentration. The NMHC test result revealed that traces of organic substance were detected in the exhaust of alkaline/acid processes. 557.7 m3 of process exhaust had to be processed for the production of a piece of generation 4.5 color filter before the aqua regia was introduced, and 1.016*10-3kWh of energy was required to process each 1m3 of process exhaust. After the aqua regia was introduced, the process exhaust to be processed was reduced to 504.6 m3 per piece of filter while 1.067*10-3kWh was required for processing 1m3 of exhaust gas.