高级检索

制粒工艺参数对MOX燃料粉末性能的影响

Effects of Granulation Process Parameters on Properties of MOX Fuel Powder

  • 摘要: 为了减少粉尘飞扬,提高MOX混合粉末的流动性能,降低生产废品率,利用Al2O3粉末模拟MOX燃料粉末,通过金相显微镜、扫描电镜及筛分分析方法等系统性开展干法制粒一体工艺技术研究,重点关注轧制压力、制粒次数、轧辊间隙及球化时间对粉末松装密度、制粒率等参数的影响规律。结果表明,随着轧制压力由2 kN·cm-1增大至18 kN·cm-1,粉末松装密度逐渐增加(由0.752g·cm-3增大至0.813g·cm-3),而制粒率呈现先增后降趋势,其峰值达87 wt.%,且压力超过10KN·cm-1时颗粒内部裂纹缺陷数量显著上升。当制粒次数从1次增至6次时,粉末松装密度持续上升,且制粒4次后制粒过程趋于稳定。轧辊间隙增大导致松装密度先升后降,其间隙优选1-2mm,制粒率则呈递减趋势。延长球化时间可使松装密度渐增并趋稳,球化时间达2小时为较优参数,可获得高松装密度(0.815 g·cm-3)的类球形颗粒,有效改善压制填充性能。

     

    Abstract: On the purpose of reducing dust dispersion, improving the flowability of MOX mixed powder and decreasing the production scrap rate, the Al2O3 powder is used to study the influence rule of rolling pressure, granulation cycles, roll gap, and spheroidization time on the MOX fuel powder's bulk packing density and granulation rate. The dry-granulation integrated technology of MOX fuel powder is systematically studied through metallographic microscopy, scanning electron microscopy and screening analysis methods. The results show that with the rolling pressure increases from 2 kN?cm-1 to 18 kN?cm-1, the loose density of the powder gradually increases from 0.752±0.002 g?cm-3 to 0.813±0.002 g?cm-3, and the granulation rate shows a trend of increasing first and then decreasing, with a peak of 87.5±0.3 wt.%. The number of crack defects inside the particles increases significantly when the pressure exceeds 10 kN?cm-1. When the number of granulation times increased from 1 to 6 times, the loose density of the powder continued to rise, but the granulation rate showed the characteristics of rising first and stabilizing. The experimental data showes that after 4 times of granulations, the proportion of powders above 150 mesh reachs 84.1±0.15 wt.%, but after 6 times of granulations, it only rise to 84.5±0.12 wt.%, indicating that the granulation process tend to be stable after 4 times of granulation. The increase of the roll gap causes the loose density to rise first and then fall, with a peak value of 0.738±0.002 g?cm-3, meanwhile, the granulation rate continues to decline. As the mixing spheroidization time extends, the loose density of the powder gradually increases and tends to be stable, the powder particles shape also change from irregular to spherical. To sum up, the pherical particles with high loose density (0.815±0.004 g?cm-3) can be stably obtained when the dry granulation process parameters are comprehensively regulated: the rolling pressure should be ≤10 kN?cm-1 to suppress particle cracks; the effective granulation rate saturates at 4 times; the roll gap size is best to be within 1 mm-2 mm; the optimal spheroidization time is 2 hours. It can effectively improving the compression and filling performance of MOX fuel powder, and providing a key technical support for the engineering application of MOX fuel.

     

/

返回文章
返回