空气中氮气或氩气浓度对锆粉尘层着火温度的影响

为了探索抑制锆包壳剪切过程中锆粉着火的方法，采用粉尘层最低着火温度测定仪、红外热成像仪、真空手套箱等测定了不同粒径的锆粉尘层在空气和含不同浓度氮气、氩气的空气中的最低着火温度和火焰温度。结果得出:锆粉的中位粒径从2.4 μm升至71.7 μm，粉尘层最低着火温度从200 ℃升至390 ℃，表明粒径越小的锆粉着火敏感性越高；4种粒径的锆粉燃烧火焰最高温度都在1 776～1 913 ℃范围内，锆粉粒径较大时，燃烧的剧烈程度较低;氮气或氩气体积分数从60%～65%升至70% 85%时，锆粉尘层最低着火温度升至400 ℃,表明空气中高浓度的氮气或氩气对锆粉燃烧有抑制作用，且浓度越高，抑制作用越强，锆粉粒径越小，抑制效果越好。氩气的抑制效果强于氮气。

Effect of Nitrogen or Argon Concentration in Air on Ignition Temperature of Zirconium Dust Layer

In order to explore the method of suppressing the ignition of zirconium powder in the shearing process of zirconium cladding, the minimum ignition temperature and flame temperature of zirconium dust layer with different particle sizes in air and air containing different concentrations of nitrogen and argon were measured by dust layer minimum ignition temperature tester, infrared thermal imager and vacuum glove box. Results show that when the median particle size of zirconium powder increases from 2.4 μm to 71.7 μm, the minimum ignition temperature of dust layer increases from 200 ℃ to 390 ℃, indicating that the smaller the particle size of zirconium powder is, the higher the ignition sensitivity is. The maximum combustion flame temperature of the four kinds of zirconium powder is in the range of 1 776-1 913 ℃, and the intensity of combustion is lower when the size of zirconium powder is larger. When the volume fraction of nitrogen and argon increases from 60%-65% to 70%-85%, the minimum ignition temperature of the zirconium dust layer rises to 400 ℃. It shows that high concentrations of nitrogen and argon have inhibition effect on the combustion of zirconium powder. The higher the concentration, the stronger the inhibition effect, and the smaller the size of zirconium powder, the better the inhibition effect. The inhibition effect of argon is stronger than that of nitrogen.