The system comprises a flow through reaction vessel having an inlet, an outlet and a reaction zone intermediate said inlet and outlet. The system further comprises reagent feed means for introducing one or more reagents into said vessel, said one or more reagents forming one or more reaction products in said reaction zone. Said reagent feed means at least include a liquid feed means for introducing a liquid into said inlet of said vessel. The vessel has a liquid evaporation zone intermediate said inlet and said reaction zone. Said liquid evaporation zone comprises an evaporation structure contacting said liquid and providing a liquid residence time in said liquid evaporation zone improving evaporation of said liquid.