Steam Jet Mixing

The Problem

This project investigated the mixing of Nitrogen into seawater in order to reduce corrosion in a ship’s ballast tanks. In order to obtain the effective mixing of a gas into water, some sort of mixing device is required. On board a ship, steam is plentiful and it was envisaged that this steam could be used to produce a highly turbulent jet that would aid the mixing process.

The Approach

Several leading edge analytical and experimental models were used to predict the flowrate of steam required at different water temperatures and water flowrate’s. From this data, appropriate nozzles were devised in order to obtain varying steam jetting regimes and to avoid a choked nozzle. Designs were then drawn up, manufactured and tested.

The Result

After a number of iterations a satisfactory design was chosen. The design was found to produce a high powered steam jet that was able to suck in a surrounding Nitrogen plume and eject it in a highly mixed state. The minimum use of steam for the maximum dissolved Nitrogen concentration was also achieved.