State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Box 266, Beijing, 100029, China.
Environ Sci Technol. 2011 Apr 15;45(8):3437-44. doi: 10.1021/es104156j. Epub 2011 Mar 7.
This work tried to identify the relationship between the internals of selective catalytic reduction (SCR) system and mixing performance for controlling ammonia (NH(3)) slip. In the SCR flow section, arranging the flow-guided internals can improve the uniformity of velocity distribution but is unfavorable for the uniformity of NH(3) concentration distribution. The ammonia injection grids (AIG) with four kinds of nozzle diameters (i.e., 1.0 mm, 1.5 mm, 2.0 mm, and mixed diameters) were investigated, and it was found that the AIG with mixed nozzle diameters in which A3, A4, B3, and B4 nozzles' diameters are 1.0 mm and other nozzles' diameters are 1.5 mm is the most favorable for the uniformity of NH(3) concentration distribution. In the SCR reactor section, the appropriate space length between two catalyst layers, which serves as gas mixing in order to prevent maldistribution of gas concentrations into the second catalyst layer, under the investigated conditions is about 100, 1000, and 12 mm for honeycomb-like cordierite catalyst, plate-type catalysts with parallel channel arrangement, and with cross channel arrangement, respectively. Therefore, the cross channel arrangement is superior to the parallel channel arrangement in saving the SCR reactor volume.
本工作旨在研究选择性催化还原（SCR）系统内部结构与氨（NH3）逸出控制混合性能之间的关系。在 SCR 流动段，布置导流内部件可以改善速度分布的均匀性，但不利于 NH3 浓度分布的均匀性。研究了四种喷嘴直径（即 1.0mm、1.5mm、2.0mm 和混合直径）的氨喷射格栅（AIG），发现 AIG 采用混合喷嘴直径（A3、A4、B3 和 B4 喷嘴直径为 1.0mm，其他喷嘴直径为 1.5mm）最有利于 NH3 浓度分布的均匀性。在 SCR 反应器段，为了防止气体浓度在进入第二层催化剂时分布不均，在研究条件下，两种催化剂层之间适当的空间长度约为 100、1000 和 12mm，适用于蜂窝状堇青石催化剂、平行通道排列的板式催化剂和交叉通道排列的板式催化剂。因此，交叉通道布置在节省 SCR 反应器体积方面优于平行通道布置。
