The Mechanical Spray Desuperheater (MSD) consists of a fixed area nozzle arranged to face the steam flow through periphery of Desuperheating pipe. The MSD relies on the pressure differential available across the jets to achieve the conditions for rapid absorption of the water into the steam.
A cooling water control valve installed in the water line ahead of the MSD will vary the water supplied to the jets. This maintains the downstream steam temperature at the measuring point. Whilst the MSD is working between approximately 5% and 100% of maximum rated capacity, there will be adequate pressure differential across the jets to ensure a spray pattern in the form of a hollow cone of finely divided water particles. Typical turndown range for a Mascot mechanical spray desuperheater can be up to 20:1. Available in sizes up to 36-inch, pressure classes up to CL4500# in a full range of castable materials.