preboiler

例句：

1. 1.The preboiler is used to preheat the water before it is heated by the main boiler.
   预锅炉用于在主锅炉加热之前预热水。
2. 2.The preboiler is an important part of the heating system that ensures the water is at the right temperature before it enters the main boiler.
   预锅炉是供暖系统中的重要部分，确保水在进入主锅炉之前达到正确的温度。
3. 3. The preboiler is designed to reduce energy consumption and improve efficiency in the heating process.
   预锅炉设计用于减少能源消耗和提高加热过程的效率。