Industrial Application of Cfd – a Review of Few Examples

The paper reviews six examples of CFD applications, useful for: minerals, power generation and oil & gas industry. The review starts with the multiphase modeling of gas injection into a liquid bath, where the CFD results were validated against experimental data. The example is very useful for metal extraction/refining industry. Simulation of a mineral concentrator bin is presented next, where multiphase modeling was used to find out the cause of blocking of the slurry pump. The 3 example presents two alternative designs, evaluated for better extraction of dust from an underground mine crushing-plant. Multiphase modeling with boiling-heat transfer was used in the next example for investigating a low pressure water cooling system in slag fumers. The next example reviews full scale coal combustion modelling of a tangentially fired boiler with mill ducting. Finally a successful modeling of a gas liquid separator is presented. The CFD software FIRE (AVL 2009) was used in most of the investigations. Geometry dimensions and process data were suppressed as necessary for confidentiality reasons. Example-1. Gas injections into liquid baths using Top Submerged Lances (TSL) There are various methods for gas injection into molten baths including Top Submerged Lance (TSL) technology, which uses a submerged vertical lance within an upright cylindrical furnace (Huda et al 2009, Floyd 1996). Through the lance, oxygen enriched air is injected with swirl into the molten bath which provides intense mixing of the bath and excellent contact between phases. Floyd (2005) has described the details of the Top Submerged Lance technology and its development since the 1970s. This paper reviews the fluid flow phenomena in a cylindrical bath stirred by Top Submerged Lance (TSL) gas injection, investigated by using CFD for an isothermal air-water system (Huda et al 2009). The multiphase flow simulation, based on the Euler-Euler approach, elucidated the effect of swirl and non-swirl flow inside the bath (Fig. 1). The effects of lance submergence level and air flow rate were also investigated in the study. The simulation results for velocity fields (Fig. 1(c)) and generation of turbulence in the bath were validated against existing experimental data from the previous model experimental study of Morsi et al. (2000). Figure 1(a) Volume fraction of liquid (TSL) (Huda et al 2009). Example-2. The mineral concentrator bin The mineral concentrator bin reviewed here was reported to show problems of accumulation of solids on the upper slanting walls. Investigations were carried out to find out the possible cause of this unusual accumulation of solids. CFD simulations were carried out for the exact operating configuration and geometries modified to overcome the problem. A quarter of the geometry was used in the model due to structural beams inside. Figure 2(a) shows the grid and Figure2 (b) shows the accumulation of solids on the upper slanting walls, which will grow with time and eventually slump into the bottom, causing blockage problem for the slurry pump suction, located at the bottom of the bin.