Large diesel engineer aftertreatment system

An aftertreatment system for a diesel engine in a marine vessel, comprising:

• the aftertreatment system in fluid communication with the diesel engine, the aftertreatment system including a first flow conduit configured to convey an exhaust gas stream, a first diffuser assembly positioned fluidly downstream of the first flow conduit, and a first selective reduction catalyst cassette positioned fluidly downstream of the first diffuser assembly including a selective reduction catalyst, the first diffuser assembly including a first airfoil fixedly attached to a first back side, and a first disperser having a honeycomb structure surrounded by a first outer frame, and wherein the first disperser has a number of cells per square inch defining a first cell density, wherein the exhaust gas stream comprises exhaust gas that has been mixed with a reductant solution and the first diffuser assembly is configured to increase the flow uniformity of the exhaust gas stream before said exhaust gas stream flows through the selective catalytic reduction catalyst.