Numerical analysis of dispersion characteristics of cooled water discharge from lng plant

To determine whether the temperature difference of cooled water discharge from open rack vaporizers conforms to environmental standard stating that the temperature decrease should be equal to or less than 3^o C within 100 meters of the discharge point, numerical simulations using CORMIX and VISJET were performed to investigate the near-field mixing behavior of staged diffuser by varying ambient currents, effluent discharges, port diameters, and discharging depths. The simulation results showed that the weak momentum and the negative buoyant properties induced the jet to change its direction to downward and to collide onto the sea bed. VISJET gives higher dilution compared with the value of dilution equation or CORMIX since the assumption of merging between adjacent jets is not adopted in VISJET model. The empirical equation tends to underestimate the dilution rate due to the assumption of complete merging of the individual jets and unidirectional dispersion trajectory. Another dispersion analysis was made regarding the further dilution by ocean turbulence, and the effect of effluent discharge on canal conveyance was checked by the calculation of the decay of mean axial velocity along the longshore direction.