Study on Wear Mechanism of Thrust Bearing of Nuclear Main Pump in Cooling Water Loss Condition
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摘要: 核主泵在核电厂断水工况下,其推力轴承失去冷源换热,推力轴承润滑介质将因轴承温度上升而不断提高润滑介质的温度,并伴随发生较复杂的热瞬态工况。当推力轴承润滑液膜厚度严重降低时,因液膜厚度不足而引发摩擦副的部分接触磨损。对某台核主泵断水试验后拆机检查,并经润滑分析断水运行工况下的磨损规律,断水工况磨损后若再进行全厂断电(SBO)惰性停机,瓦面随着磨损深度增加,轴承油膜厚度降低至无法可靠运行程度,损耗增加且伴随着油膜温度超过巴氏合金运行极限温度110~120℃,易引发轴承严重磨损。本研究可为优化轴承及提高磨损后SBO惰性停机的耐磨损能力提供理论支撑。Abstract: When the nuclear main pump is in the cooling water loss condition of the nuclear power plant, its thrust bearing loses cold source heat transfer. The temperature of the lubricating medium of the thrust bearing will be continuously increased due to the temperature rise of the bearing, which is accompanied by more complicated thermal transient conditions. When the thickness of the lubricating liquid film of the thrust bearing is seriously reduced, the contact wear of the friction pair occurrs due to the insufficient thickness of the liquid film. A nuclear main pump is disassambled and checked after a water cut-off test, and the wear pattern of the water cut-off operating conditions through lubrication is analyzed. When the station blackout (SBO) inert shutdown is carried out in the water cut-off condition, with the increasing of wear depth, the oil film thickness of the bearing decreases to the extent that it cannot operate reliably, and the loss increases. With the oil film temperature exceeding the Babbitt alloy operating limit temperature of 110-120℃, serious wear of the bearing is prone to occur. It provides a theoretical support for optimizing the bearings and improving the wear resistance of multiple SBO inert shutdowns after wear.
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表 1 某型主推力瓦润滑计算对比
Table 1. Lubrication Calculation Comparison of a Type of Main Thrust Pad
计算参数 CFD法 有限差分法 入口油温/℃ 60 60 60 推力载荷/kN 535 535 535 转速/(r·min−1) 1500 1500 1485 最小油膜/mm 21 19.1 19 表 2 主推力轴承1485 r/min参数
Table 2. Parameters of Main Thrust Bearing at 1485 r/min
工况编号 入口油温/℃ 工作载荷/kN 工况1 15 535 工况2 20 535 工况3 40 535 工况4 60 535 工况5 65 535 表 3 主推力轴承1485 r/min油膜厚度
Table 3. Parameters of Main Thrust Bearing at 1485 r/min
工况编号 最小油膜
厚度/mm最大油膜
厚度/mm最大油膜
压力工况1 0.054 0.134 0.5611 工况2 0.046 0.114 0.5611 工况3 0.027 0.067 0.5611 工况4 0.019 0.046 0.5611 工况5 0.017 0.043 0.5611 表 4 设备冷却水变动主推力轴承油膜厚度
Table 4. Oil Film Thickness of Main Thrust Bearing when Cooling Water of Equipment Changes
转速/
(r·min−1)入口油
温/℃推力载
荷/kN最小油膜
厚度/mm最大油膜
厚度/ mm归一化最大
油膜压力750 41.721 770 0.015 0.038 0.5611 1485 41.721 535 0.026 0.064 0.5611 750 61.006 770 0.011 0.026 0.5611 1485 61.006 535 0.018 0.044 0.5611 表 5 主推力轴承断水8e工况参数
Table 5. Parameters of Main Thrust Bearing when Water Loss Working Condition 8e
转速/
(r·min−1)推力瓦
内径/mm推力瓦
外径/mm瓦数 入口
油温/℃工作
载荷/kN1485 Φ380 Φ730 10 75 535 表 6 主推力瓦不同磨痕深度润滑性能
Table 6. Lubrication Performance of Main Thrust Pad with Different Wear Depth
转速 磨痕
深度/mm最小油膜
厚度/μm润滑功率
损失/kW最高油膜
温度/℃500 r/min 瓦面完整 0.014 16.9 105 0.025 0.005 23 141 0.05 0.004 27.2 134 350 r/min 瓦面完整 0.012 10.1 105 0.025 0.004 14.1 143 0.05 0.004 16.6 126 -
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