The Research And Application Of Adding Oxygen In Feedwater Of The 1000MW Ultra-supercritical Tower Boiler System

With the increasing application of 1000MW ultra supercritical units, although all the power plants can control the water and steam quality strictly, the qualified rate of water and steam are high.Many power plants in a short period of time occur the iron oxide jam in boiler, serious causticity and fast rising of boiler pressure. Even some power plants need acid pickling in less than a year. By changing the way of water supply and decreasing the content of iron in the boiler feedwater, it can reduce the boiler water wall tube iron oxide decomposition rate and the corrosion of thermal system,enhance the usage life of boiler, decrease the time of washing and increase the economic benefits of boiler. The way of water supply and oxygen supply is the most effective.This paper briefly introduces the basic theoretical knowledge of water supply and oxygen supply at home and abroad and analyzes the economic advantages and the impact on the unit. Combine with the practice of water supply and oxygen engineering in Ninghai power plant with two 1000MW ultra supercritical units. This paper emphasizes and tracks the 1000MW units system situation and the water and steam quality by combining with oxygen for thermal system material and water quality requirements. Oxygen supply needs to be confirmed and the system needs to be checked. Aiming at different conditions, the change of oxygen content in water vapor before and after the addition of oxygen in 1000MW unit, the influence of PH change, the change of iron ion in each system and the change of water cycle are discussed. This paper also analyses that the iron anion is rising in the process of adding oxygen and discusses the lots of anion separation and processing method in the feedwater, which can provide a reference for theory study and project.