The deaerator modification scheme resolves the issue of unreasonable water source design for the pump's sealing, ensuring the safe operation of the gas boiler, and also achieves good economic and social benefits. After extensive testing, adjustments, and analysis, it was found that the excessive oxygen content in the deaerator's feedwater was caused by the pump's sealing water source being不合理. In fact, the feedwater oxygen content meets the standard. The modification of the deaerator has effectively addressed the issue of oxygen content exceeding the limit, which was caused by directly mixing softened water from the pump's sealing cooling shaft seal into the transmission medium of the feed pump.