Jan Erik Olsen

A parcel based modelling concept for studying subsea gas release and the effect of gas dissolution

A modelling concept for analysing the fate of a subsea gas release is presented. The concept is based on a coupled Eulerian–Lagrangian method. The gas bubbles are modelled and tracked as parcels in a Lagrangian Discrete Phase Model (DPM). The continuous water and atmospheric gas are covered by an Eulerian VOF model. The model accounts for compressible gas effects, bubble size, gas dissolution and is fully transient. It compares well with experiments from a release depth of 7 m. The concept is applied to a set of release scenarios and the results are presented.

Mechanisms and Kinetics of Boron Removal from Silicon by Humidified Hydrogen

The removal of boron from silicon by top blowing of humidified hydrogen has been studied in the present work through experimental work, thermodynamic calculations, computational fluid dynamic modeling, and quantum chemistry calculations. The effect of process parameters; temperature, lance diameter, lance distance from the melt surface, gas flow rate, and crucible material on the kinetics of boron removal were studied. It has been shown that the rate of boron removal is decreased with increasing temperature due to the competitive reactions between silicon and oxygen as well as boron and oxygen, which can be confirmed with the increases of pSiO/pHBO in the system. The rate of boron removal is increased with increasing the gas flow rate due mainly to the better supply and transport of the gas over the melt surface, as confirmed by the CFD modeling. Moreover, the rate of boron removal in alumina crucible is the highest followed by that in quartz and graphite crucibles, respectively. Faster B removal in quartz crucible than that in graphite crucible can be attributed to more oxygen dissolves in silicon melts. The fastest boron removal in alumina crucible is attributed to the additional boron gasification through aluminum borate (AlBO2) formation on the melt surface. Thermodynamic properties of the AlBO2 species have thus been revised by quantum chemistry calculations, which were more accurate to describe the formation of gaseous AlBO2 than those in the JANAF Thermochemical Tables. The main chemical reactions for boron gasification from silicon melts are proposed as

Model of Silicon Refining During Tapping: Removal of Ca, Al, and Other Selected Element Groups

{\text{In graphite, quartz and alumina crucible}}:\quad \underline{\text{B}} + \underline{\text{H}} + \underline{\text{O}} = {\text{ HBO}}\left( {\text{g}} \right)

CFD modeling of plume and free surface behavior resulting from a sub-sea gas release

In graphite, quartz and alumina crucible:B̲+H̲+O̲=HBOg

Current understanding of subsea gas release: A review

{\text{In alumina crucible}}:\underline{\text{Al}} + \underline{\text{B}} + \underline{\text{O}} = {\text{ AlBO}}_{2} \left( {\text{g}} \right)

Mass transfer between bubbles and seawater

In alumina crucible:Al̲+B̲+O̲=AlBO2gBased on the obtained results, it has been proposed that boron removal from silicon melt by humidified hydrogen is controlled both by the chemical reaction for boron gasification and mass transport in the adjacent gas phase.