超超临界锅炉过热器管超温蠕变应力松弛规律研究

林齐叠; 严祯荣; 王化南; 陈乐; 卫荆涛

超超临界锅炉过热器管超温蠕变应力松弛规律研究

1.
上海工程技术大学机械与汽车工程学院, 上海 201620
2.
上海市特种设备监督检验技术研究院, 上海 200062

基金项目: 上海市市场监督管理局科技资助项目（NO：2021-27）

详细信息

作者简介:
林齐叠（1995−），男，在读硕士，研究方向为特种设备安全技术. E-mail：875557423@qq.com

通讯作者:
严祯荣（1972−），男，教授，博士，研究方向为能源清洁利用和设备安全技术. E-mail:yanzr2010@163.com

中图分类号: X933
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出版历程
- 收稿日期: 2021-09-07
- 刊出日期: 2022-02-23

Study on relaxation rule of over temperature creep stress in superheater tube of ultra-supercritical boiler

1.
School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
2.
Shanghai Institute of Supervision & Inspection Techniques for Special Equipment, Shanghai 200062, China

摘要

摘要: 超超临界锅炉高温过热器集箱出口区域的过热器管易处于超温运行的环境，产生蠕变应力松弛导致材料失效. 基于Norton蠕变模型，以烟气温度750℃、蒸汽温度600℃、蒸汽压力26 MPa的运行工况，模拟T91过热器管壁在长时间热诱导中产生的应力松弛行为及蠕变分布. 模拟结果显示，过热管应力松弛现象首先发生在管内壁面，随着时间累计沿着径向方向扩散；10000 h后内壁面出现应力松弛且松弛加速；同时管壁面在应力松弛的过程中发生高温蠕变行为，且蠕变行为首先出现在内壁面并沿着径向扩散，内壁面蠕变程度高于外壁面；10000 h后管壁面厚度开始减薄. 研究结果表明：超超临界锅炉过热器管超温运行10000 h是蠕变应力松弛到蠕变损伤的时间拐点.
- 超超临界锅炉 /
- 过热器管 /
- 蠕变 /
- 应力松弛 /
- 时间拐点
Abstract: The superheater tube in the outlet area of the high-temperature superheater box of ultra-supercritical boiler is easy to be exposed to overtemperature environment, resulting in creep stress relaxation and material failure. Based on Norton creep model, the stress relaxation behavior and creep distribution of T91 superheater tube wall during long-term thermal induction were simulated under the operating conditions of flue gas temperature of 750℃, steam temperature of 600℃ and steam pressure of 26 MPa. The simulation results show that stress relaxation phenomenon of the heat pipe firstly occurs on the inner wall and spreads along the radial direction with time accumulation. After 10000 h, the inner wall surface appears stress relaxation and relaxation accelerates. At the same time, high temperature creep behavior also occurs on the tube wall during the stress relaxation process, and the creep behavior firstly appears on the inner wall and spreads along the radial direction, and the creep degree of the inner wall is higher than that of the outer wall. After 10000 h, the thickness of pipe wall begins to decrease. The results show that the overtemperature operation of superheater tube of ultra-supercritical boiler for 10000 h is the time point from creep stress relaxation to creep damage.
- ultra-supercritical boiler /
- superheater tube /
- creep /
- stress relaxation /
- time point

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图 1 过热器管模型图

Figure 1. Superheater tube model diagram

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图 2 过热器管网格图

Figure 2. Superheater tube grid diagram

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图 3 过热器管壁温度场分布

Figure 3. Temperature field distribution of tube wall of superheater

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图 4 过热器管壁应力分布规律

Figure 4. Stress distribution law in tube wall

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图 5 管壁径向应力随时间变化

Figure 5. Variation of radial stress of tube wall with time

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图 6 不同时间壁面径向位置应力分布

Figure 6. Stress distribution in radial position of wall surface at different times

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图 7 过热器管壁蠕变分布图

Figure 7. Creep distribution of superheater tube wall

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图 8 不同时间过热器管壁径向蠕变分布

Figure 8. Radial creep distribution of superheater tube wall at different times

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图 9 壁厚随蠕变时间的变化

Figure 9. Variation of wall thickness with creep time

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表 1 T91物性参数

Table 1. Physical parameters of T91

参数	温度/℃
参数	500	600	700
导热系数/(W·m⁻¹·K⁻¹)	29	29	29
线膨胀系数/K⁻¹	1.21×10⁻⁵	1.24×10⁻⁵	1.26×10⁻⁵
比热容/ (J·kg⁻¹·K⁻¹)	630	800	860
密度/(kg·m⁻³)	7770	7770	7770
弹性模量/GPa	181	168	165
泊松比	0.3	0.3	0.3
屈服强度/MPa	410	326	158

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表 2 烟气与蒸汽物理参数

Table 2. Physical parameters of flue gas and steam

蒸汽压力/ MPa	蒸汽温度/ ℃	烟气温度/ ℃	蒸汽换热系数/ (W·m⁻²·℃⁻¹)	烟气换热系数/ (W·m⁻²·℃⁻¹)
26	600	750	2053.65	123.51

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表 3 网格统计

Table 3. Grid statistics

最小尺寸/mm	平均尺寸/mm	四面体数量/个	三角形数量/个	顶点数量/个	边单元数量/个	网格顶点数量/个
0.1953	0.6586	101952	10172	16	496	19563

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表 4 T91钢蠕变参数

Table 4. Creep parameters of T91 steel

参数	温度/℃
参数	600	620	625
n	16.36	14.25	7.70
B	1.259×10⁻⁴⁰	7.409×10⁻³⁵	3.786×10⁻¹⁹

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表 5 T91过热器管壁面不同径向位置仿真与试验等效应力

Table 5. Simulation and experimental equivalent stress of T91 superheater tube wall at different radial positions

过热器管壁径向位置/mm	10.1	14.5	19.0
10 h后应力仿真结果/MPa	62.3	30.1	18.2
10 h后应力试验值/MPa	63.5	30.9	19.0
10⁴ h后应力仿真结果/MPa	58.7	31.2	18.2
10⁴ h后应力试验值/MPa	57.4	30.5	17.8
10⁵ h后应力仿真结果/MPa	51.0	32.1	18.7
10⁵ h后应力试验值/MPa	52.3	34.7	20.9

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表 6 T91过热器管壁面厚度仿真与试验测量值

Table 6. Simulation and experimental measurements of tube wall thickness of T91 superheater

参数	仿真值	试验测量值
壁面厚度/mm	8.996	8.994

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