Computational study of Fe3O4 adsorption behaviour on the secondary side of the heat exchange tube in the steam generator
Computational study of Fe3O4 adsorption behaviour on the secondary side of the heat exchange tube in the steam generator
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DOI：
10.1016/j.commatsci.2021.110471
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发表时间：
2021-07
影响因子：
3.3
通讯作者：
Lu Ren;Jian Xu;W. Jia;Hongying Yu;T. Shoji;Tong-Yi Zhang;Ning Li;Dong-Yang Zhang;Dong-bai Su
中科院分区：
文献类型：
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作者：
Lu Ren;Jian Xu;W. Jia;Hongying Yu;T. Shoji;Tong-Yi Zhang;Ning Li;Dong-Yang Zhang;Dong-bai Su
针对压水堆二回路工况下蒸汽发生器管外表面结垢问题，采用分子动力学方法计算了Fe 3 O 4的吸附特性。通过温度和浓度的变化，进一步分析了Fe 3 O 4团聚和沉积过程的轨迹、均方位移、径向分布函数和吸附能。当温度在510 K ~ 530 K之间时，Fe 2+和OH-的扩散系数分别达到最小值2.255 × 10- 5cm 2/s和2.638 × 10- 5cm 2/s。在Fe ~（2+）浓度变化过程中，团聚体颗粒尺寸不断增大，H_2O扩散系数最小可达3.78 × 10 ~（-5）cm ~ 2/s。带正电荷的Fe 2+能有效地与H2O和OH−团聚，形成四面体和八面体结构的Fe 3 O 4晶体。此时，少量OH-吸附在基体界面，形成双电层，影响团聚Fe 3 O 4的沉积。此外，高温有利于部分抑制结垢沉积。同样，溶解的Fe 2+和OH−的低浓度也会导致团聚的Fe 3 O 4在蒸汽发生器二次侧的外结垢层上的沉积较弱。
Based on the scaling problem on the outer surface of the steam generator tube in the secondary circuit condition of pressurized water reactor, the molecular dynamic was used to calculate the adsorption characteristics of Fe3O4. The trajectory, mean squared displacement, radial distribution function and adsorption energy of Fe3O4agglomeration and deposition process were further analyzed through variation of temperature and concentration. When the temperature was between 510 K and 530 K, the diffusion coefficient of Fe2+and OH−could reach the minimum value of 2.255 × 10-5cm2/s and 2.638 × 10-5cm2/s, respectively. During variation of Fe2+concentration, the size of agglomerate particles increased continuously, and the diffusion coefficient of H2O can reach the minimum value of 3.78 × 10-5cm2/s. Fe2+with positive charges can effectively agglomerate with H2O and OH−, forming the tetrahedral and octahedral structures of Fe3O4crystal. At this time, a small number of OH−were adsorbed at the interface of the matrix, forming the double electrical layer and affecting the deposition of agglomerated Fe3O4. Apart from this, high temperature is beneficial to inhibit scaling deposition in part. Likewise, low concentration of the dissolved Fe2+and OH−can also lead to weaker deposition of agglomerated Fe3O4on the outer scaling layer of the secondary side in the steam generator.