Fill in the blanks based on the attached video-clip about a brief introduction to boilers in thermal power plant. 爱剪辑-steam boiler2.mp4 1. Burners in the boiler convert the chemical energy in the ___________ into thermal energy. 2. The first heat absorption unit of the boiler is the ___________, where highly-pressured water supplied by the feed-water pump enters. 3. From there, the water flows into a _______ to the downcomer, and it then passes through the narrow section called ______. 4. The real function of the steam drum is to _______the ________________ from the steam. 5. ___________ and ___________ also increase the powerplant's capacity and efficiency.