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Show 2 handling, use and disposal of gases and vapors used to etch, or deposit on, silicon wafers presents a formidable safety task, and that are highly toxic, carcinogenic, or combustible ( 1,2 ) . Taiwan semiconductor industries are located in Hsinchu scientific park where is neighborhood to residential area having high density population, Taiwan EPA has regulated strict process exhaust emission since 1996, and most industries have taken ISO-14000 excise to achieve a cleaner production and meet the regulation as well. A typical microelectronics fabrication process employs from six to twelve VOCs, i.e., 1,1,1-trichloroethane, isopropyl alcohol, xylene, n-butyl acetate, 2-ethoxyethyl acetate, and propylene glycol monomethyl ether acetate, the stream of VOCs concentrations range from 100 to 1,500 p p m and gas range from 1,200 to 20,000 cfm. Among few available control technologies, combustion technologies such as thermal and catalytic oxidation have an extensive history of providing reliable control of VOCs for high concentration and middle exhaust gas volume (3) . During microelectronic circuit fabrication, a thermal reaction product, Si02, m a y be coating on the catalyst surface, renders catalytic oxidation ineffective for VOCs removal (4) . On the other hand, reaction products containing halogenated VOCs can degrade precious metal catalysts during the processing (5) , therefore, thermal oxidation is selected as the maximum achievable control technology (MACT) in this presentation despite catalytic oxidation has an advantage to operate at lower temperatures. As Taiwan EPA regulations governing the control of air emissions have become stricter, combustion technologies have kept pace with these emerging demands - 95 % + destruction efficiency is now commonplace. In the combustion process, hydrocarbon ( HCs) are combined with oxygen to form water vapor and carbon dioxide. Thermal oxidation requires the combustion process to take place in a chamber at temperatures between 650°C and 900°C and with residence times of 0.5 to 2.0 seconds depending on the components of VOCs and their inlet concentration. Heat recovery, either recuperative or regenerative, is normally incorporated into the thermal oxidizer design to reduce supplemental fuel requirements purpose, a comparison of operation cost among combustion technologies indicates that the advantage of regenerative combustion (6) . Because most local microelectronic industries are facing land shortage problem as market expansion is forecasted, thus it is required to |
