In the operation of gas-fired hot water boilers, it is necessary to deoxygenate the feed water. The main reason is that oxygen is the main corrosive substance in the boiler water supply system. The oxygen in the water supply system should be removed quickly, otherwise it will corrode the boiler water supply system and components, and the corrosive iron oxide will enter the boiler, deposit or adhere to the boiler On the pipe wall and heating surface, insoluble but poor heat transfer iron scale is formed. Corroded iron scale will cause pits on the inner wall of the pipe and increase the resistance coefficient.
Therefore, in order to ensure the safe operation of the boiler, it is necessary to deoxygenate the boiler feed water; in the national standard "Industrial Boiler Water Quality" (GB1576-2001), the country puts forward strict requirements on boiler water quality, requiring evaporation Steam boilers with a capacity greater than 2t/h and hot water boilers with a rated power ≥4.2MW must be deoxygenated.
Zhengzhou Fangkuai Boiler Factory has summarized some operating skills when deoxygenating the feed water of gas-fired hot water boilers, hoping to help users better use the boilers.
1. Thermal deaeration
Thermal deoxygenation can not only remove oxygen in water, but also carbon dioxide or other gases. The deoxygenated water will not increase the salt content, nor will it increase the dissolved amount of other gases, the operation control is relatively easy, and the operation is stable and reliable.
2. Vacuum deaeration
Vacuum deaeration is performed at lower than atmospheric pressure (vacuum degree 600~700mmHg). It belongs to low temperature deaeration. Then the so-called vacuum deaeration shows one thing, that is, the degree of vacuum must be maintained. The quality of vacuum deaeration effect is closely related to the degree of vacuum.
3. Chemical deoxygenation
Chemical deaeration is also divided into different types, steel scrap deoxidation; sodium sulfite deoxidation; hydrazine deoxidation; resin deoxidation, etc. Different types of chemical deaeration methods have different characteristics. Of course, the water temperature requirement of chemical deaeration is greater than 70°C, 80~90°C has the best effect, and 20~30°C has the worst effect of deoxygenation.
4. Analysis and deaeration
The working principle of deoxygenation is to intensively mix and contact the oxygen-free gas with the feed water to be deoxygenated, so that the oxygen dissolved in the water is desorbed into the gas, so that the feed water achieves the purpose of deoxygenation through such circulation.
You can choose the appropriate deaeration method according to your own use of gas-fired hot water boiler to achieve the purpose of deaeration.