Abstract: A nozzle design for diffusing high pressure steam into by flowing process fluid of substantially lower pressure while reducing the noise intensity generated. The injection nozzles include an opening having a first diameter to receive steam and a second diameter to inject the steam into a flow of liquid. The diameters of the first and second openings can vary relative to each other to enhance the flow characteristics of the steam or other gas being injected into a flow of liquid. The outer surface of a diffuser tube is coated with an insulating material, such as plastic. In alternate embodiments, the orientation of the injection holes can be angled either upstream or downstream to further enhance mixing characteristics of the steam.