ljungstromCOCA³¹⁵¹¹¹⁺⁴ 基本例句 🌏容氏 In 1991, the boiler's rear heat absorbing part was completely retrofitted by installing a new type two stage spiral spline tube air preheater instead of the original Ljungstrom one. 1991年对锅炉尾部受热面进行了彻底改造，采用两级新型螺旋槽管式空气预热器取代了回转式空气预热器； cnki