Study on the effects of oxygen enrichment modes on the tuyere raceway states of blast furnace
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摘要: 依据国内某企业冶炼钒钛磁铁矿高炉的实际尺寸建立了三维物理模型，利用数值模拟的方法对比研究了不同富氧方式下煤粉在风口回旋区内的流动、燃烧行为。结果表明，减风富氧与定风富氧方式工况下，风口气流速度变化随富氧率变化的整体趋势一致，但变化幅度差距显著，即富氧率增加1%，风口截面速度分别增加4.25 m/s（定风）和0.41 m/s（减风）。两种富氧方式下，回旋区内的温度、还原气体含量及煤粉燃尽率与富氧率的变化趋势一样，即富氧率增加，温度增加，高温区域扩大，还原气体含量增加，煤粉的燃尽率上升。其中，减风富氧时由于热风流量减小，带入高炉的N2量减少，煤气中CO和H2的含量变化较大，对高炉减少氮化碳和碳化钛生成、改善铁矿还原效果具有较好的帮助，建议高炉提高富氧率采用减风富氧模式。经计算，富氧率每增加1%，回旋区平均温度增加34.22 K（定风）和32.88 K（减风）；减风富氧条件下，富氧率每增加1%，热风带入高炉的N2量减少10 m3/min，煤气中的CO质量浓度上升8.61%。Abstract: In this paper, based on the actual dimension of the vanadium titanomagnetite blast furnace of a domestic enterprise, a three-dimensional physical model is established. The numerical simulation method is used to compare and study the flow and combustion behavior of pulverized coal in the tuyere gyration area under different oxygen enrichment methods. The results show that the overall trend of the tuyere velocity change with the oxygen enrichment rates is consistent with that of the constant air enrichment mode, but the difference in the change amplitude is significant. That is, when the oxygen enrichment rate is increased by 1%, the cross-sectional velocity of the tuyere is increased by 4.25 m/s (fixed air) and 0.41 m/s (reduced air), respectively. Under the two oxygen enrichment modes, the temperature, reducing gas content and burnout rate of the pulverized coal in the gyratory area have the same trend with the oxygen enrichment rates. As temperature increases, the high temperature area expands with the increase in the reducing gas content, and the burnout rate of pulverized coal increases. Among them, the amount of N2 brought into the blast furnace decreases due to the decrease in hot air flow rate, and the content of CO and H2 in the coal gas changes greatly, preventing the formation of carbon nitrides and titanium carbides, and improving the reduction effect of iron ore in the blast furnace. It is calculated that the average temperature of the gyratory zone is increased by 34.22 K (fixed air) and 32.88 K (reduced air) for every 1% increase in the oxygen enrichment rate. Under the condition of reduced air and oxygen enrichment, the N2 content brought into the blast furnace is reduced by 10 m3/min and the CO concentration in the gas is increased by 8.61%.
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Key words:
- blast furnace /
- oxygen-enriching mode /
- raceway status /
- CFD numerical simulation
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图 2 沿风口中心线方向气体温度变化
Figure 2. Changes in gas temperature along the center line of the tuyere
图 4 定风富氧不同富氧率下的速度场分布
Figure 4. Velocity field distribution at different oxygen enrichment rates
图 5 定风富氧下富氧率变化时沿煤粉流股温度变化
Figure 5. The variation of temperatures along the pulverized coal stream when the oxygen enrichment rate changes
图 6 定风富氧时不同富氧率下回旋区内的最高温度和平均温度
Figure 6. Maximum and average temperatures in the raceway at different oxygen enrichment rates
图 7 不同富氧率条件下风口、回旋区内气体分布
Figure 7. Gas distribution in the tuyere and raceway under different oxygen enrichment rates
图 8 沿煤粉流股中心线上气体成分变化
Figure 8. Changes in gas composition along the centerline of the pulverized coal stream
图 10 减风富氧条件下气体速度变化
Figure 10. Changes in gas velocity under reduced air and oxygen enrichment conditions
图 11 减风富氧条件下沿煤粉流股中心线上气相温度变化曲线
Figure 11. Variation curves of gas phase temperature along the center line of pulverized coal stream under reduced wind and oxygen enrichment conditions
图 12 减风富氧条件下风口中心线上CO2和CO含量随富氧率的变化
Figure 12. Curves of CO2 and CO contents on the center line of the tuyere when the oxygen enrichment rate changes
图 13 减风富氧条件下回旋区出口处煤粉燃尽率
Figure 13. under reduced wind and oxygen enrichment conditions
表 1 高炉的实际操作条件
Table 1. Actual operating conditions of blast furnaces
风口数/个 高炉有效容积/m3 风量/(m3·min−1) 风压/kPa 氧气浓度/% 煤比/(kg·t−1) 热风温度/℃ 载气成分 24 1750 4000 360 24（基准工况） 95 1220 氮气 
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表 2 定风富氧条件下富氧率变化时的风量
Table 2. The air volumes with changes of the oxygen enrichment rates of the fixed air
序号 定风富氧率/% 总风量（工况条件）/(m3·min−1) 热风流量（工况条件）/(m3·min−1) 直吹管入口速度/（m·s−1） 煤枪入口速度/（m·s−1） 1 3 4157.89 4000 195.77 12.50 2 5 4270.27 4000 201.07 12.50 3 7 4388.89 4000 206.65 12.50 4 9 4514.29 4000 212.56 12.50 5 11 4647.06 4000 218.81 12.50
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表 3 减风富氧富氧率变化时的风量条件
Table 3. Air volumes with changes of the oxygen enrichment rate of the reduced air
序号 减风富氧率/% 总风量（工况条件）/(m3·min−1) 热风流量（工况条件）/(m3·min−1) 直吹管入口速度/(m·s−1） 煤枪入口速度/（m·s−1） 1 3 4157.89 4000 195.77 12.50 2 5 4157.89 3895 195.77 12.50 3 7 4157.89 3789 195.77 12.50 4 9 4157.89 3684 195.77 12.50 5 11 4157.89 3579 195.77 12.50
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表 4 沿煤粉流股上最高温度和回旋区内平均温度
Table 4. Maximum temperatures along the distance from lance tip and average temperature in the raceway
减风富氧率/% 沿煤粉流股中心线最高温度/K 回旋区平均温度/K 3 2859.87 2676.71 5 2912.92 2767.03 7 2976.11 2838.74 9 3027.91 2895.40 11 3071.75 2939.71
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