Prediction of Circulation Flow Rate in the RH Degasser Using Discrete Phase Particle Modeling

Abstract

Conservation equations for mass and momentum with a two equation k-e model are solved for the continuous phase along with a discrete phase particle modeling (representing gas bubbles) in the RH degasser to predict the circulation flow rate of water in a scaled down model and then the numerical solution has been extended to the real plant case for the prediction of steel circulation flow rate in the actual RH vessel. The prediction of the circulation flow rate of water from the present numerical solution matches reasonably well with that of the experimental observation, taking into account various uncertainties those have been imbedded in the numerical model. RH operation for multi up legs and single down leg for a water model shows that the circulation flow rate falls with the number of up legs and there is an optimum number of down legs for which the circulation flow rate is the maximum for the case of a single up leg. For the actual RH operation in plant it was seen that the circulation flow rate increases with the increase in snorkel diameter and snorkel immersion depth (SID). However, it is apparent that there is existence of optimum SID for maximum circulation flow rate. For different down leg immersion depth the circulation flow rate in the RH depends heavily on the up leg immersion depth. The actual RH operation of the plant for the multi up leg and down leg cases was found to be exactly similar in nature to that of the water model cases.KEY WORDS: circulation flow rate; multi leg RH; discrete particle modeling. 495

Investigation of Gas and Liquid Multiphase Flow in the Rheinsahl–Heraeus (RH) Reactor by Using the Euler–Euler Approach

“…In the Euler-Lagrange approach, liquid is treated as a continuum by solving the Navier-Stokes equations, whereas gas is solved by tracking a large number of bubbles through the calculated flow field. As demonstrated by Kishan,25 the predicted circulation rate with this approach for water modeling was considerably less than observation. Actually, the Euler-Lagrange approach requires that the gas-holdup is generally less than 12%.…”

“…More importantly, these empirical correlations were obtained experimentally under a single nozzle; 20-23 nevertheless, a big difference of the gas-holdup distribution and plume shape were observed between multiple nozzles and a single nozzle in the case of horizontal gas blowing. 24 To overcome the shortcomings with the homogeneous fluid model, multiphase models, i.e., EulerianLagrangian and Eulerian-Eulerian approaches, [25][26][27][28][29] were put forward. In the Euler-Lagrange approach, liquid is treated as a continuum by solving the Navier-Stokes equations, whereas gas is solved by tracking a large number of bubbles through the calculated flow field.…”

Fluid Mixing in Ladle of RH Degasser Induced by Down Flow

“…Zhang et al 7) built a decarburization model by adding the fluid flow in the vacuum vessel and ladle. The flow pattern of steel melt in the ladle was analyzed by the computation fluid dynamics (CFD) [6][7][8][9][10][11][12][13][14][15] and perfect mixing time 14,15) was also calculated by the time-change in a tracer concentration at a given point after a tracer injection.…”

Effect of Traveling Magnetic Field on Flow, Mixing, Decarburization and Inclusion Removal during RH Refining Process

“…[8][9][10][11][12][13][14][15][16][17][18][19] Some researches showed that the circulation flow rate is mainly determined by the vacuum degree and the lifting gas flow rate, [8][9][10][11][12] and it is difficult to increase the circulation flow rate after reaching its saturation value. 8,9) Meanwhile, several measures have also been taken to increase the circulation flow rate and shorten mixing time, such as increasing the diameter of the up snorkel and the down snorkel, 13) using the oval-shape-snorkels, 10) replacing one up snorkel and one down snorkel by three up snorkels and one down snorkel, 14) two up snorkels and one down snorkel or one up snorkel and two down snorkels, 12) applying rotating magnetic field around the up snorkel, 15) blowing additional argon gas, (e.g. blowing argon gas through vacuum chamber bottom 16) and ladle bottom 17,18) ) and so on.…”