| abstract |
An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, a first ammonia injector configured to inject ammonia into the exhaust gas pathway at a first rate, and a first treatment element positioned downstream of the first ammonia injector. A second ammonia injector is positioned downstream of the first treatment element. The second ammonia injector is configured to inject ammonia into the exhaust gas pathway at a second rate. A controller is configured to estimate an amount of particulate present in the exhaust gas and adjust at least one of the first rate or the second rate based on the estimate. |