现在，这个发光的球体迅速扩大，像氮气球一样升起。
Now the glowing ball expanded quickly , rising like a helium balloon .
针对传统凯氏定氮装置存在的问题，设计了一种新型的定氮装置，尤其对氮气球、通气开关、球型冷凝管进行了重新设计。
An improved Kjeldahl equipment which focusing on the spherical condenser , ventilation switches and the ball for nitrogen had been designed .
氮气球