Aftertreatment system having two SCR catalysts

摘要

A system and method includes an internal combustion engine capable of producing an exhaust stream and an aftertreatment system operationally coupled to the exhaust stream. The aftertreatment system includes an upstream selective reduction catalyst (SCR) component and a downstream SCR component that are positioned in substantially different thermal environments. The upstream and downstream SCR components are sized to fully treat the entire exhaust stream at a low temperature highest NOx conversion condition, and the downstream SCR component is sized to fully treat the entire exhaust stream at a high temperature highest NOx conversion condition.

主权项

1. A system, comprising:
an internal combustion engine capable of producing an exhaust stream; an aftertreatment system operationally coupled to the exhaust stream, the aftertreatment system comprising an upstream selective reduction catalyst (SCR) component and a downstream SCR component, wherein the upstream SCR component is positioned in a substantially different thermal environment than the downstream SCR component when the internal combustion engine is producing an exhaust stream; an upstream reductant delivery device positioned upstream of the upstream SCR component and a downstream reductant delivery device positioned between the upstream and downstream SCR components; and wherein the upstream SCR component and the downstream SCR component are sized to fully treat the entire exhaust stream at a first highest NOx conversion condition corresponding to at least one of cold start and warm-up operating conditions of the system with reductant delivered only from the upstream reductant delivery device, and wherein the downstream SCR component is sized to fully treat the entire exhaust stream at a second highest NOx conversion condition corresponding to operating conditions of the system during at least one of an aftertreatment component regeneration event and a particulate filter regeneration event with reductant delivered only from the downstream reductant injector and with reductant delivery from the upstream reductant delivery device prevented during the at least one of the aftertreatment component regeneration event and the particulate filter regeneration event.