Pressure degassing
Water contains oxygen and carbon dioxide. Both cause corrosion in the steam network. The concentration of oxygen and carbon dioxide decreases as the temperature rises. This effect is used to degas the feed water in the feed water tank.
JUMAG pressure degassing:
Function and benefits
What is the purpose of pressure degassing and what are its advantages?
Heating above 103°C minimizes corrosive gases
In unpressurized vessels, where the temperature is usually between 90°C and 95°C, a large proportion of the oxygen and carbon dioxide is already driven out of the water. However, not all gases escape, and these can continue to cause rapid damage to steam pipes and steam generators unless they are bound with dosing agents.
If the temperature of the feed water vessel is increased to above 103°C, the concentration of oxygen and carbon dioxide is negligible.
Less dosing agent required, less frequent blowdown
This means that less dosing agent is required. The reduced salt content of the dosage also has a positive effect on the blowdown intervals.
In order to achieve a water temperature of over 103°C, the water must be under pressure. This is referred to as pressure degassing or full degassing – in contrast to partial degassing at below 100°C in unpressurized vessels.
Additional energy savings
In addition, a high proportion of condensate return due to the higher water temperature saves up to 1.6% energy (corresponding to 6.5 kW for a JUMAG DG560 steam generator).
Further information on JUMAG pressure degassing
Available for all feed water vessels
JUMAG offers pressure degassing for all JUMAG feed water vessels in combination with the latest boiler control system.
Patented control system: Greater savings compared to other systems
The patented JUMAG control system for the vent valve saves significantly more energy compared to other systems, as venting only takes place when there is oxygen in the system.
How it works in detail:
A temperature sensor measures the temperature in the feedwater vessel and maintains it at the desired temperature (usually 100°C) by supplying steam to the water area.
The pressure in the feed water vessel is also measured and maintained at the desired pressure.
A solenoid valve, which is opened in cycles depending on the fresh water supply (and thus the supply of O2 and CO2), expels the harmful gases from the feed water vessel together with a small amount of steam.
Safe and TÜV-monitored and approval-free
The feed water vessel is supplemented by a safety valve that limits the pressure to a maximum of 0.5 bar. This means that the feed water vessel remains TÜV-monitored and approval-free. The safety valve must be designed according to the capacity of the connected steam generators.
If there is a lot of condensate return, the pressure in the feed water vessel can rise to over 0.5 bar. For this reason, JUMAG pressure degassing is equipped with an overflow valve that opens at a pressure between 0.2 and 0.5 bar to prevent frequent opening of the safety valve.
If the feed water tank overflows, a signal is sent from the level gauge to a drain valve, which opens accordingly.
If negative pressure builds up in the vessel, a solenoid valve and a mechanical check valve open. The solenoid valve located under the feed water vessel performs the functions of venting, overpressure limitation, overflow, and negative pressure limitation.
Basic equipment
- Safety valve limited to 0.5 bar pressure
- Integrated overflow valve that opens at approximately 0.3 bar upstream of the safety valve
- Vacuum breaker
- Angle seat valve for pressure maintenance
