The Flow Performance of Combined Gas Blowing at the Vacuum Chamber and Up-Snorkel in the Ruhrstahl–Heraeus (RH) Degasser for Electrical Steel Production

In the production process of electrical steel, with respect to the industrial RH (Ruhrstahl–Heraeus), the steel producers must balance the high-circulation flow rate (operating efficiency) and the frequent cleaning of cold steel in the vacuum chamber due to the splashing of liquid steel (high maintenance costs). Excessive lifting gas flow can induce splashing, causing cold steel to adhere to the inner walls of the vacuum chamber. To address this issue, this study utilized an 80-ton RH vacuum refining unit from a specific plant as the research prototype and established a 1:2.6 scale water model for physical model simulation. Two innovative blowing methods were implemented by adding gas injection nozzles to the sidewalls and to the bottom of the vacuum chamber, respectively. The study investigated the effects of altering the blowing method on liquid surface fluctuations, flow patterns, the circulation flow rate, and the mixing time without changing the total gas flow rate. For the macroscopic flow in the RH unit, implementing side-blowing on the sidewalls of the vacuum chamber can accelerate the diffusion rate of the ink tracer, whereas implementing bottom-blowing in the vacuum chamber has little effect on the diffusion rate. The results show that modifying the blowing method can effectively reduce liquid surface fluctuations and suppress the splashing behavior within the vacuum chamber. Firstly, implementing side-blowing causes the ink tracer flow pattern within the vacuum chamber to become triangular, to increase the circulation flow rate, to shorten the residence time of the ink tracer within the chamber, and simultaneously to promote mixing in the ladle, which reduces the mixing time. Secondly, implementing bottom-blowing results in the formation of a gas column at the center of the vacuum chamber, which suppresses fluid flow within the chamber. Compared with side-blowing, it reduces the circulation flow rate and increases the mixing time in the ladle. Combined gas blowing through the up-snorkel and sidewalls is effective in solving splashing issues and reducing the mixing time in RH vacuum refining, and this method is a good candidate for industrial applications.