Rotary film deaerator is an alternative to spray-packed deaerator. It is a newest thermal deaerator. The principle of rotary film deaerator is that water is sprayed at a certain angle through the film tube in a spiral shape. The steam is heated for heat exchange and deoxygenation, the feed water is heated to the saturation temperature corresponding to the working pressure of the deaerator, the oxygen and other gases dissolved in the feed water are removed, and the corrosion of boiler feed water pipes, economizers and other auxiliary equipment is prevented and reduced. The Ministry of Electric Power’s GB1576-2001 “Safety Technical Supervision Regulations for Pressure Deaerators in Power Stations” has proposed a ministerial standard for the oxygen content of deaerators, that is, the oxygen content of low-pressure atmospheric deaerator feed water should be less than 15цɡ/L, The oxygen content of the oxygenator feed water should be less than 7цɡ/L.
The structure of the rotating film deaerator is mainly composed of a shell, a rotating film nozzle, a water grate, a filler liquid vapor net, a water tank, a soda separator, etc.:
- Shell: It is made of cylinder body and stamped circular head welding. Medium and small low-pressure deaerators are equipped with a pair of flanges to connect the upper and lower parts for assembly and maintenance. The high-pressure deaerator is equipped with manholes for maintenance.
- Rotating film nozzle: It is composed of water chamber, steam chamber, rotating film tube, condensate connection pipe, supplementary water connection pipe and primary steam inlet connection pipe. A water film guiding device is added in the film tube of the new type of film spinner, which can spin the film powerfully even when running under low load, and maintain a good water film skirt.
The condensed water and chemical make-up water are spirally sprayed out at a certain angle through the film-forming tube to form a water film skirt, and exchange heat with the heating steam introduced by the primary heating steam connection to form a primary deoxygenation. The feed water rises through the water grate. The secondary heating steam contact is heated to close to the saturation temperature under the working pressure of the deaerator, that is, 2-3°C lower than the saturation temperature, and rough deoxygenation is performed. Generally, 90-96% of the oxygen content in the feed water can be removed through this rotating film section.
- Water grate: It is composed of several layers of staggered angular steel pieces. The feed water that is roughly deoxidized by the spin film section is distributed twice here, and falls into the liquid vapor net installed under it in the form of uniform rain and mist.
- Packing liquid vapor net: SW-type mesh corrugated packing composed of many units of the same shape and size, forming a cylindrical body. This structured packing maintains the advantages of wire mesh corrugated packing and orifice corrugated packing, and Large flux, small pressure drop, large operating flexibility, high separation efficiency, low energy consumption, and never fall off. The heat storage packing itself is the heat accumulator of the secondary steam. The feed water and the heat accumulator are fully heat exchanged to achieve the purpose of deep deaeration. The low-pressure atmospheric deaerator is less than 10ug/L and the high-pressure deaerator is less than 5ug/L.
- Water tank: The deaerated feed water is collected in the lower container of the deaerator head, that is, the water tank. The deaerator water tank is equipped with the latest scientifically designed powerful heat exchange and re-boiling device, which has powerful heat exchange, quickly raises the water temperature, and more depth Deaeration.