Numerical Modeling of the Tuyere Surface Abrasion under Different Operating Conditions of Blast Furnace

Abstract

Blast furnace (BF) has been widely used for iron making [1] to provide pig iron for steel making. As shown in Figure 1, raw material, iron ore, coke, and limestone are charged into the BF from the top and the hot air is blown into the BF from the tuyeres at the bottom. Pulverized coal injected (PCI) into the BF by hot air decreases the coke consumption because the coke is more expensive than coal. The PCI causes a complex region around the tuyere where different phases interconnect. Carried by the high-swirling gas, coal and coke particles will move vigorously and collide on the tuyere surface. Some scratches and dents appear on the tuyere surface (see Figure 1). Tuyere failure leads to furnace instability and productivity reduction. A worn tuyere has the risk of high pressure cooling water entering the BF, which not only threatens the BF safety but also stops the BF due to repair or optimization of tuyeres significantly reduces the BF output.Additionally, PCI changes the temperature distribution in the raceway (the void zone next to the outlet of the tuyere) due to the combustion of injected air with coal. The tuyere is made of copper considering its excellent thermal conductivity and corrosion resistance. The copper's hardness is sensitive to the temperature, and thus the erosion is highly affected by PCI and the cooling system. Nowadays, air and pulverized coal are not the only fuel injected into the BF. For example, high-concentration oxygen, or recycled carbon monoxide [2] is also injected together with air to lower the carbon footprint. Thus, the combustion in the raceway is influenced by different operating conditions, resulting in far from being understood of tuyere erosion in the BF.Recent studies focused on the failure pattern of the tuyere with the discussion of the effect of the cooling system. Among four failure patterns (i.e., erosion, pitting, cracking, and bending), erosion was the most common one [3,4] including melt erosion and abrasion. Abrasion was also a key problem for tuyere failure, [5] which is affected significantly by hardness of the tuyere material relevant to temperature. A simulation study of water circuit in the cooling system demonstrated that the highest temperature was on the top part of the tuyere tip, i.e., the vulnerable zone of the tuyere, which was consistent with the worn tuyere in the production line. [6] The limescale has been found as a key factor affecting the temperature in the cooling system. [7,8] The encrustation of limescale reduced the heat conduction, increased the temperature of the tuyere, and resulted in melting loss. Recycled carbon monoxide or enriched oxygen used in modern or future BFs can influence the temperature in the raceway region. Current studies have been done on the

Analysis of Erosion Mechanism of Wear‐Resistant Layer in Large Blast Furnace Tuyere

“…[ 1 ] Blast furnace tuyere operates for a long time in an environment with a temperature above 2000 °C, and withstands the scouring of hot air and coal powder with high temperature and high speed, as well as the impact of slag, hot metal, and hot coke. [ 2,3 ] The frequent damage of the copper tuyere severely affects the smooth operation of the blast furnace. Tuyeres in large blast furnaces are generally made of pure copper.…”