短语词组短语convection box type heater 烟气下行式对流箱式炉down -convection box type heater 烟气下行式对流箱式炉;烟道气下行对流箱式加热炉radiant and convection type heater 辐射对流型炉natural -convection type air heater 自然对流型空气加热器 返回 convection type heater