公开(公告)号：US5853683A

公开(公告)日：1998-12-29

申请号：US840841

申请日：1997-04-17

申请人： Francis X. Gibbons ,  Alexander L. Huhmann ,  Albert J. Wallace

发明人： Francis X. Gibbons ,  Alexander L. Huhmann ,  Albert J. Wallace

IPC分类号： B01D53/56 ,  B01D53/86 ,  F23J15/00 ,  B01J8/00

CPC分类号： F23J15/006 ,  B01D53/56 ,  B01D53/8625 ,  F23J2215/10 ,  F23J2219/10 ,  F23J2219/20

摘要： A process for reducing the level of nitrogen oxides (NO.sub.x) in a fossil fuel (e.g. coal) combustion flue gas has a selective non-catalytic reduction (SNCR) treatment stage followed by a selective catalytic reduction (SCR) treatment stage. The level of NO.sub.x produced by a power plant, particularly a coal fired power plant, varies depending upon the plant load. A set predetermined non-zero amount of first nitrogenous treatment agent is constantly introduced for the SNCR stage during all periods of plant operation. Additional first nitrogenous treatment agent is introduced for the SNCR stage only during periods of relatively higher NO.sub.x production, such as during peak load periods. A second nitrogenous treatment agent is added for the SCR stage up to the maximum SCR NO.sub.x reducing capability of the SCR stage based upon the total amount of NO.sub.x present in the flue gas, subject to limitations on the amount of allowable ammonia slip exiting the plant. Once the total amount of NO.sub.x in the flue gas surpasses a level which the SCR stage can effectively treat, additional first nitrogenous treatment agent is added to the SNCR stage. The amount of additional first nitrogenous treatment agent added is incrementally raised as the NO.sub.x level increases. During relatively lower NO.sub.x producing periods when the set non-zero amount of SNCR plus the SCR stage alone are effectively capable of reducing the level of NO.sub.x to the desired level without surpassing ammonia slip limits, no additional treatment agent is added for the SNCR stage.

摘要翻译： 用于降低化石燃料（例如煤）燃烧烟道气中的氮氧化物（NOx）水平的方法具有选择性的非催化还原（SNCR）处理阶段，随后是选择性催化还原（SCR）处理阶段。 发电厂，特别是燃煤发电厂产生的NOx水平因工厂负荷而异。 在工厂运行的所有时段期间，为SNCR阶段不断地引入一定的非零量的第一含氮处理剂。 仅在氮氧化物产生相对较高的时段（例如峰值负荷期间），为SNCR阶段引入额外的第一种含氮处理剂。 对于SCR级添加第二种含氮处理剂，直到基于烟道气中存在的NOx总量的SCR级的最大SCR NOx还原能力，受限于离开设备的允许氨滑移量的限制。 一旦烟气中的NOx总量超过SCR级可以有效处理的水平，则在SNCR阶段加入另外的第一种含氮处理剂。 随着NOx含量的增加，附加的第一种含氮处理剂的量逐渐增加。 在相对较低的NOx生成期间，当SNCR加上SCR阶段的设定非零量素能够有效地将NO X的水平降低到所需水平而不超过氨的滑移限值时，对于SNCR阶段不再添加另外的处理剂。