An exhaust processing element for processing the engine exhaust comprises a housing having an inlet and an outlet. The mixing device is positioned in the housing between the inlet and outlet, the mixing device comprises a flow reversing device is disposed proximate a decomposition tube, and a second end provided with a shell, a first end and a second end that is in communication with the vent. The first end extends from the shell and configured to receive exhaust from the inlet, and is configured to receive reagent fluid exhaust treatment. The second end is located within the shell. Flow inversion apparatus doedoe configured to direct the mixture of the exhaust emission control liquid and reagent in a predetermined direction in the shell, the flow reversing device is in turn reversing the flow direction of the exhaust towards the first end of the exploded pipe.