In order to guarantee the quality of super-high-pressure steam, it is necessary to regularly drain the quench boiler where the super-high-pressure steam generates. Due to the high temperature and pressure of blowdown water and the frequent switching operation, serious internal leakage often occurs at the blowdown valve, leading to a lot of waste. To save energy and improve economic benefit, cascade recovery of waste heat was carried out for the leaking blowdown water through calculations, achieving the goals of energy saving, consumption reduction and efficiency improvement.