Erosion Behavior of Blast Furnace Tuyere

Self Cite

Water‐cooled copper tuyeres of blast furnace are subjected to intense thermal conditions. Several modifications are attempted to prevent tuyere failure as the impact of failure is severe. What has, however, gone unnoticed is the peak “Cold face” temperature in tuyere and its implication. Numerical model incorporating water flow and conjugate heat transfer with a feature to identify onset of boiling by analytical correlations is developed. It is ascertained that, in tuyeres, the temperature of the Cold face exceeds the saturation temperature at the prevailing pressure by an amount high enough to cause nucleate boiling. The implication of the onset of boiling is discussed and a design modification is suggested by changing the aspect ratio of cooling passage. The impact of velocity distribution to achieve lower peak “Cold face” temperature is discussed. Modified design shows almost zero boiling prone zone for the range of operating parameters studied. Fourteen modified tuyeres are placed alongside original designed tuyeres in an blast furnace. The newly designed tuyeres outperform their counterparts. This approach to identifying and suppressing boiling of water in the cooling channel—a hitherto neglected phenomenon—gives an additional input towards designing a more robust tuyere.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of Flow Boiling on Blast Furnace Tuyere Life: A Designer's Perspective

Chatterjee

Nag

Kundu

et al. 2021

Self Cite

“…They found that the erosion types of the tuyeres are very complex and can be classified into four categories: melting erosion, point erosion, cracking, and deformation of the tuyere. Chatterjee et al [ 8 ] found that there is a significant amount of material loss at the front end of the tuyere compared to other parts of the tuyere. To reduce erosion at the top of the tuyere, better wear‐resistant materials should be sprayed in this area to enhance the life of the tuyere.…”

Section: Introductionmentioning

confidence: 99%

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

Zhou

Zhang

et al. 2023

The blast furnace tuyere is a crucial component for blast furnace production. The frequent damage of the copper tuyere impedes the smooth operation of the blast furnace. Welding a wear‐resistant layer on the tuyere can extend its service life, but it still falls short of the expectation in a large blast furnace. This paper aims to elucidate the erosion mechanism of the wear‐resistant layer. A scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), and an optical microscope (OM) were employed to examine the morphology, composition, and metallographic structure of the samples obtained from a 5800m3 blast furnace tuyere in China, as well as to calculate the frequency of daily slag crust shedding from cooling staves. The results indicate that the main cause of the erosion of the wear‐resistant layer is the shedding of slag crust due to the temperature fluctuation of the cooling staves. Finally, the erosion mechanism of the wear‐resistant layer is proposed. It is suggested that the formation and propagation of cracks caused by erosion of slag and hot metal are the primary failure mode of the wear‐resistant layer.This article is protected by copyright. All rights reserved.

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

et al. 2022

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