natural circulation boiler

例句：

1. 1. The naturalcirculation boiler is designed to efficiently heat thewater for domestic use.
   自然循环锅炉设计用来高效地为家庭用水加热。
2. 2. The naturalcirculation boiler was installed in the factory's main building.
   自然循环锅炉安装在工厂主楼。
3. 3. The natural circulation boiler has a longlifespan and low maintenance costs.
   自然循环锅炉具有长寿命和低维护成本。