Department of Environmental Protection, Taipei City Government

1. Our waste gas treatment equipment includes semi-dry scrubber and bag filter dust collector. We also inject active carbon powder at the exhaust pipe between semi-dry scrubber and bag filter dust collector to adsorb dioxin and reduce it to 0.1ng-TEQ/Nm3, O2, 11%.
2. We also have a optional non-catalytic reaction equipment at the incinerator’s combustion chambers to remove nitrogen oxides (NOx). For designing and operation of semi-dry scrubber + active carbon injector + bag filter dust collector system, the following points need to be cautioned:
(1) The size of semi-dry scrubber and the selection of rotary atomizer are important. The adsorbent and exhaust shall be well mixed to ensure effective neutralizing and adsorption. Usually, it is required to choose the highest class of rotary atomizer, and make the size of semi-dry scrubber large enough to let gas retention time reaching 10~15 sec.
(2) The optimum adsorbent using amount should be higher than the essential amount for neutralizing acidic gas. Usually, 1.5~2.0 times of essential amount of slake lime is used. But the actual slake lime amount is different for each incinerator. Therefore, the using amount of slake lime can only be determined after practical tests. However, it shall be specially cautioned that too much slake lime would provide more contact surface and increase dioxin generation.
(3) Bag filter dust collector has better dioxin removal efficiency than electrostatic precipitator, because filter bags can adsorb and remove dioxin in exhaust. The lower the temperature of the passing waste gas and the slower the passing speed, the better the performance.