电厂换热管束冲蚀磨损数值模拟分析

Numerical Simulation of Erosion Effecton the Heat Exchange Tube in Power Plant

电厂锅炉高温换热器受热面在含尘烟气长时间磨损的作用下,会出现吹蚀减薄迹象,导致换热器爆管,使得机组被迫停机。为了揭示飞灰颗粒对换热管束冲蚀磨损的影响,采用欧拉-拉格朗日方法以及Oka模型分别模拟颗粒运动和管壁冲蚀磨损情况,通过用户自定义函数描述颗粒物与壁面的反弹效果,对不同粒径和不同管排下的磨损情况进行了分析。结果表明,管排布置方式会对换热管束冲蚀磨损产生影响,具体表现:第一排换热管受颗粒的冲击磨损影响较显著,面平均磨损量随颗粒粒径的增大而增大;横向间隙减小时,换热面平均磨损速率减弱,换热管纵向间距对磨损的影响不大,管束叉排布置时,磨损量增加。数值模拟结果加深了电厂高温换热器磨损规律的认识,通过换热管束的合理布置,有助于减少磨损,提高系统运行的可靠性。

The heating surface of the high-temperature heat exchanger of the power plant boiler work sintheen vironment so flong-term wear, which will reduce the thickness of heating tube, causing the heat exchanger to burst and the powergenerating unit is forced to shut down. In order to reveal the influence of fly ash particles on the erosion and wear of heat exchange tube bundles, the Euler-Lagrangian method and Oka model were adopted to simulate particle movement and tube erosion respectively, and the rebound effect of particles with wall was introduced by a user-defined function. The erosion effects under different particle diameters and different tube rows were analyzed. The results showed that the erosion and wear effect can be influenced by the arrangement of tube rows, more specifically, the first row of heat exchange tubes were significantly affected by the impact of particles, and the average surface wear increased with the increase of the particle size. When the transverse gap decreased, the wear of the particles was weakened, the longitudinal spacing had little impact on erosion rate, and the wear rate increased when the fork row was arranged. The understanding of the wear laws of high-temperature heat exchangers in power plants were deepen by thenumerical simulation. A reasonable arrangement of heat exchange tube bundles can help to reduce the wear effects and improve the reliability of system.