Vacuum Degasser

　　Vacuum Degasser

　　It is well known that some air inevitably exists in heating and cooling water circulation systems, originating from system make-up water and pipeline leaks. This air exists in the system in three forms:

　　The first scenario is when gas accumulates in the system as an air pocket at high points or localized high points, such as pipeline bends and the top of heat exchangers (radiators or fan coil units).

　　The second form is when gas circulates within the system along with the water in the form of free bubbles.

　　The third form is when gases dissolve in water and circulate with the water. Among the three forms of gas occurrence mentioned above, the first two are free gases.

　　The third type is dissolved gas; the three forms can continuously interconvert, but in the absence of external environmental changes, the concentrations of each form remain relatively stable.

　　Air dissolved in water can have numerous adverse effects on heating and cooling water circulation systems. Accumulated gas creates air locks, leading to uneven system resistance, impaired circulation, and the generation of noise and cavitation. These issues reduce the pump’s effective head and operating efficiency, shorten the service life of equipment and piping networks, and decrease heat-transfer performance due to bubble formation on heat-exchanger surfaces. Air locks also make system commissioning more difficult and necessitate frequent manual air venting during operation. Moreover, dissolved oxygen in the system can cause oxidative corrosion, which further reduces system lifespan and directly compromises overall system safety.

　　The vacuum degasser employs the differential-pressure degassing principle and is suitable for any water system. Its exceptionally strong degassing capability ensures the safe and rapid removal of both free and dissolved gases from the system, thereby enabling the system to operate safely and reliably.

　　Working Principle

　　According to Henry’s Law, a fixed amount of gas dissolves in water at a given temperature and pressure. When the temperature rises or the pressure drops, the amount of dissolved gas in the water decreases; conversely, when the temperature falls or the pressure increases, the amount of dissolved gas increases. By creating a vacuum within the equipment without changing the water temperature, both free and dissolved gases are released from the water and then discharged from the system via an automatic air vent. The degassed water is subsequently re-injected into the system. This low-concentration water is unsaturated and highly absorbent of gases; it will continuously absorb gases from the system in order to achieve gas–water equilibrium. Through this cyclical process, all gaseous impurities in the system water are ultimately removed.

　　Characteristics

　　1. Versatile functionality: A single unit is suitable for systems with a water volume of 150 m³ and operating pressures up to 6 bar, 10 bar, or 15 bar; it automatically replenishes the system with deaerated water; maintains stable system pressure; and employs intelligent control to optimize the degassing process.

　　2. Plug-and-play: The degasser is easy to install and operate, and its flexible connections make it compatible with any system.

　　3. Advanced degassing process: employs a safe and reliable closed-loop degassing system with high processing capacity.

　　4. Energy conservation: The system automatically reads system information and only powers on equipment when necessary.

　　5. Reduce costs: Shorten the commissioning period to bring the system online as quickly as possible, monitor system status, and only start the degasser when required.

　　6. High efficiency: The vacuum degasser achieves degassing and deoxygenation efficiencies of over 99%.

　　Test results

　　Yuanjie Company conducted degassing and deoxygenation tests on its vacuum degassing (deoxygenation) unit. The equipment is designed for systems with a water volume of 100 m³, operates at temperatures between 5°C and 90°C, features a degassing cycle time of 30 seconds, and has a rated water treatment capacity of 1 to 1.5 m³/h. The test water was tap water, and electric heating was used for temperature elevation.

　　Testing has shown that at a water temperature of 70°C, the equipment achieves a vacuum level of -0.08 MPa gauge pressure, with a dissolved oxygen concentration in the effluent of 0.083 mg/L. The venting volume per cycle is 9 mL.

　　Scope of Application

　　Vacuum degassing and deoxygenation units are suitable for a wide range of heating and cooling water circulation systems. The operating time and cycle of the degasser can be adjusted as needed, with each unit capable of handling systems up to 100 m³ in capacity; for large circulation systems, multiple units can be operated in parallel.

　　The vacuum degassing and deoxygenation unit can significantly shorten the venting time after the initial water filling of heating or cooling systems, which is highly beneficial for the system’s initial commissioning and operation. By continuously removing gases from the system online and preventing air locks, it ensures stable and reliable operation throughout the system’s service life. It also eliminates pump cavitation and reduces operational noise. Furthermore, by removing dissolved oxygen from the water, it mitigates oxygen-induced corrosion, thereby extending equipment lifespan. In addition, no gas bubbles adhere to the heat exchanger surfaces, enhancing heat transfer efficiency. As this equipment employs vacuum degassing and deoxygenation, there is no risk of secondary contamination. The unit is easy to install, features fully automatic control, operates safely and reliably, and is simple to maintain and service.

　　Installation and Usage

　　In principle, a vacuum degasser can be installed at any point in a heating or cooling system; however, it is most suitable for installation on the system’s return line. The pressure at the installation point should remain within the system’s operating pressure range, and the water temperature at that point should preferably not exceed 60°C.

　　When a vacuum degasser is installed in a heating system, its installation location shall be no less than 15 meters from the highest point of the system. When a vacuum degasser is installed in a refrigeration system, its installation location shall be no less than 5 meters from the highest point of the system.