Boiler deaerator/thermal deaerator

Deoxygenation is a crucial step in the boiler feedwater treatment process. Oxygen is the main corrosive substance in the water supply system and boiler. The oxygen in the water supply should be quickly removed, otherwise it will corrode the water supply system and components of the boiler. The corrosion product, iron oxide, will enter the boiler and deposit or adhere to the boiler tube wall and heating surface, forming iron scale with poor heat transfer. Moreover, corrosion will cause pitting on the inner wall of the pipeline, resulting in an increase in resistance coefficient. When pipeline corrosion is severe, pipeline explosion accidents may even occur. According to national regulations, steam boilers with an evaporation capacity of 2 tons per hour or more and hot water boilers with a water temperature of 95 ℃ or more must be equipped with boiler deoxygenation devices.

1、 The function of boiler deaerator：
Boiler deaerator is mainly used to remove oxygen and other non condensable gases from boiler feedwater to ensure the quality of feedwater. If oxygen is dissolved in water, it will corrode the metal in contact with the water. At the same time, if gas accumulates in the heat exchanger, it will increase the thermal resistance of heat transfer and reduce the heat transfer efficiency of the equipment. Therefore, any gas dissolved in water is unfavorable, especially oxygen, which will directly threaten the safe operation of equipment. Thermal deoxygenation is commonly used in thermal power plants, and the deaerator of the thermal boiler itself is a hybrid heater in the feedwater reheating system. At the same time, the drainage, chemical makeup water of the high-pressure heater, and high-pressure drainage, exhaust steam, etc. with qualified water quality throughout the plant can be combined into the deaerator of the thermal boiler for utilization, reducing the loss of steam and water in the power plant.

2、 Classification of deaerators for rotary film thermal boilers produced in Yongtong, Sichuan：
The rotary film thermal boiler deaerator can be divided into pressure (high-pressure) thermal deaerator and low-pressure (atmospheric pressure) thermal deaerator.
Low pressure rotary film boiler deaerator is commonly used in industrial boilers and small thermal power plants, and it can be divided into high or low (zero) position arrangements.
Low pressure rotary membrane boiler deaerator arranged in low (zero) position is particularly suitable for various industrial boilers and can effectively save construction investment.

3、 Structure of deaerator for rotary membrane thermal boiler：
The structural type of boiler deaerator mainly consists of an outer shell, a steam water separator, a rotary jet membrane generator, a water spray grate, a regular liquid steam network, and a water tank.

1. Shell: It is made by welding a cylindrical body and a stamped elliptical head.
2. Soda water separator: The rotary film thermal deaerator replaces the traditional straw hat cone structure design in the deaerator, eliminating the phenomenon of steam carrying water in the deaerator.
3. Spiral jet membrane generator: composed of a water chamber, a steam chamber, a membrane generator, a condensate pipe, a supplementary water pipe, a drainage pipe, and a primary steam inlet pipe. A water film guide device has been added to the rotary film tube of the rotary film launcher, which can strongly lower the film even during low load operation and maintain the optimal rotary film skirt. Condensed water, chemical makeup water, and water film are sprayed out in a spiral shape at a certain angle through the membrane tube to form a water film skirt. They come into contact with the heating steam introduced through the primary heating steam pipe and the secondary heating steam rising from the water tank through the liquid steam network and water grate, and are heated to a saturation temperature close to the working pressure of the deaerator (i.e. 2-3 ℃ below the saturation temperature) for crude deoxygenation. Generally, about 90-95% of the oxygen content in the feedwater can be removed through this membrane section.
4. Drinkling grate: It is composed of several layers of staggered angular steel components. The feed water, which has undergone coarse deoxygenation in the membrane section, and the water drained by the high-pressure heater are mixed here for secondary distribution, and uniformly rained onto the liquid vapor screen installed below it.
5. Regular packing liquid vapor network: It is a cylindrical body composed of many SW type mesh corrugated packing units with the same opening size. This regular packing maintains the advantages of wire mesh corrugated packing and orifice plate corrugated packing, and has the characteristics of large surface area, low pressure drop, high operating elasticity, high separation efficiency, low energy consumption, and never falling off. The feedwater is fully in contact with the secondary steam here, heated to saturation temperature and subjected to deep deoxygenation. The low-pressure atmospheric deaerator is ≤ 10PPb, and the high-pressure deaerator is ≤ 5PPb.
6. Water tank: The deoxygenated feed water is collected in the feed water tank of the lower container of the deoxygenation head. The deoxygenation water tank is equipped with the latest scientifically designed strong heat exchange and reboiling device, which has the advantages of strong heat exchange, rapid increase in water temperature, deeper deoxygenation, reduced water tank vibration, reduced noise, etc., improving the service life of the boiler deaerator and ensuring the safety and reliability of equipment operation.

4、 Characteristics of rotary film thermal boiler deaerator：
Good deoxygenation effectThe deoxygenated water content is ≤ 30 μ g/L during unit start-up and ≤ 7 μ g/L (high-pressure type) to 157 μ g/L (low-pressure type) during operation, fully meeting the requirements of the "Water and Steam Quality Standards for Thermal Power Plants" and meeting the current international standards.
Strong adaptability：
Suitable for high water-soluble oxygen content at the inlet (low-pressure type: 10000 μ g/L, high-pressure type: 20000 μ g/L);
Low inlet water temperature (low-pressure type: 13 ℃; high-pressure type: 60 ℃);
When operating under large pressure changes (low-pressure type: 0.02-0.05MPa, high-pressure type: 0.02-0.98MPa), the operating mode can be used for sliding pressure, constant pressure, or negative pressure operation.
Good stabilityWhen the load suddenly changes by 25% and an additional 10% of feedwater is added instantly, when using a low-temperature steam source, the deoxygenated water can still be qualified when the inlet water temperature drops significantly, and the boiler deaerator will not experience abnormal situations such as vibration.
energy conservationThe exhaust steam volume is small, which is 1/2 to 1/3 less than other types of thermal deaerators with the same output and less than 1 ‰ of the inlet water volume. No additional exhaust steam cooler is required, simplifying the system and reducing heat consumption. The water spraying density is high, up to 180m3/m2 · h. Due to the small volume of the rotary membrane boiler deaerator, it can save a lot of steel and investment compared to other types of thermal deaerators with the same output.

Technical parameters of boiler deaerator/thermal deaerator: