| 摘要 |
<p>A hot mix asphalt plant has a catalytic reactor (16) which can effectively and reliably reduce VOC and NOx emissions produced during plant operation. The reactor effectiveness is enhanced by exhausting the gas stream from a primary dryer (12) of the plant at a sufficiently high temperature for effective catalytic reaction. Since withdrawal of gases from the dryer at these elevated temperatures necessarily reduces the effectiveness of the dryer, overall plant efficiency is maintained by using the treated gas stream from the catalytic reactor to heat further the aggregate in a secondary dryer (14), which is preferably a finishing dryer such as fixed sleeve dryer drum coater. Poisoning of the catalyst is avoided by removing at least a large portion of the dust in the gas stream via a high efficiency cyclone (18) prior to introducing the gas stream into the catalytic reactor. Gas exiting the secondary dryer may be further treated in baghouse assembly (22). Ammonia (20) or urea may if desired also be injected into the gas stream prior to its introduction into the catalytic reactor.</p> |
