Acoustic Analysis of Slag Foaming in the BOF

Abstract

The control of slag foam that is produced during the Basic Oxygen Furnace (BOF) process has been the subject of significant research. The behaviour of slag foams is complex. Hence, the control of slag foam in the dynamic process of the BOF is challenging. Acoustic analysis of the BOF is one of the most promising methods for the indirect measurement of slag foam height. This paper reviews different studies on the fundamental behaviour of acoustics in liquid foams and various acoustic studies related to determining the slag foam height during the BOF process. Studies on the BOF have been carried out using both cold water models and plant trials, where acoustic measurements taken directly from the process were analysed. These studies showed that the attenuation of sound through liquid foam was influenced mainly by factors such as viscosity, bubble size, and foam height. Current systems are said to be 70 to 87 per cent accurate in detecting and/or predicting slopping events in the BOF, though there is a lack of systematic data in the literature to fully quantify this accuracy. There have been various attempts to combine sound with vibration and image signals to improve the prediction of slopping events in BOFs. The review substantiates the lack of accuracy of the current systems in determining the slag foam height using acoustic analysis and the need to address fundamental questions about the behaviour of sound in dynamic foam, its reliance on different factors, and the relatability of comparing cold model data to industrial data.

多相融体の流動特性評価とプロセスシミュレーション

“…、Hara ら 5,6) 、Kitamura and Okohira 7) の研究、および、Hara and Ogino 8) のレビューがある。試験転炉および実機転炉でフォーミング高さについても Tatsukawa ら 9) の報告がある。また、フォーミング高さだけでなく、気泡の滞留時間やフォ ーミングインデックスを対象とした検討については、高温スラグを用いた実験や冷間モデ ル実験での結果が Ito and Fruehan [10][11][12] を始めとして多数報告されている [13][14][15][16][17][18][19][20][21][22][23][24] 。転炉スラグフ ォーミングの状態を音響情報から検討する報告 25) もある。また、火山分野では粒子や気泡 を含む溶岩やマグマの粘度を高温流体、あるいは、それを模擬する流体を使って検討され 3 ている [26][27][28][29][30][31][32][33] 。土木工学や建築分野でも、モルタルやセメントなどを対象に、粒子が分散し た 2 相流体をビンガム流体とした実験および評価、数値計算に関する研究が多数実施され ている [34][35][36][37] Roscoe の式(6) 43) 、Yagi and Ototake の式(7) 44) 、Krieger and Dougherty の式(8) は、少量の液体粒子の存在はフォーミングを助長すること、をそれぞれ報告している。…”