The present invention provides a mixing device (1) for mixing urea With a gas, said urea being preferably dissolved in a fluid preferably Water and said gas being preferably air. The mixing device comprises preferably a urea inlet (10) and a gas inlet (12) for feeding respectively urea and the gas into a mixing chamber (20) of the mixing device (4), and an outlet (14) for outlet of the mix of urea and gas from the mixing chamber (20) , these inlets (10,12) and outlet (14) may preferably have a stream Wise extension and runs preferably into the mixing chamber (20) and the outlet (14) originates preferably from the mixing chamber (20). Preferably, at least the gas inlet (12) for feeding air into the mixing chamber is designed so that depositing of urea crystals on selected surfaces of the said inlet is substantially (typically in the sense that deposited crystals does not clog the inlet) or totally avoided.