Alstom - Deaerator and Feedwater Tank
From Gas Power
To prevent corrosion, the feedwater supplied to the boiler and steam generators of the thermal and nuclear power plants should not contain more than a few micrograms of oxygen per litre water. The deaerator incorporated into the feedwater heating circuit eliminates continuously the residual oxygen and non-condensable gases contained in the condensate
The Alstom deaerator is designed to offer sustained reliability across a wide range of operating conditions, including extreme conditions. It is also largely maintenance-free, which means higher plant availability and greater cost-efficiency.
Safety and efficiency
Optimized efficiency due to very small steam flow required for venting and feedwater heating. There is no risk of water return to the turbine. The Alstom deaerator offers good deaeration over the entire load range.
A variety of different arrangements can be provided to fit all types of power plants (fossil-fired, nuclear, combined cycle, etc.) and all operating conditions.
The Alstom deaerators are subject to the company’s stringent quality and design standards, which are applied to deaerators as well as all Alstom power plant equipment.
The deaerator operates as a direct-contact heater.
It is associated with a feedwater storage tank to form a single unit. The storage tank acts as a reservoir of deaerated and heated water for water balance in the watersteam cycle of the power plant.
The Alstom “spray, trays and reboiling” design in three stages:
- Condensate is sprayed at the top of the deaerator through nozzles, heated and partially deaerated
- By passing through a number of trays, the condensate water is further deaerated and completely heated
- Oxygen free feedwater is assured by supplying continuously heat to the deaerated feedwater by hot water, steam or a combination of hot water and steam.
This technique is very versatile, allowing different deaerating arrangements to meet different operating conditions:
- A vertical dome deaerator for small power stations or industrial applications
- A horizontal dome deaerator for fossil-fired power stations
- A horizontal dome deaerator operating with saturated or slightly superheated steam and used in power plants up to 1500 MW
- Or an integrated deaerator.
The feedwater storage tank can be equipped with additional devices such as pre-heating steam supply drain inlets and condensate distribution pipes.
- Condensate oxygen content up to 10’000 ppb
- Oxygen removal to less than 7 ppb over a wide operation range
The Alstom deaerator and storage tank solutions can be tailored to meet a wide variety of customer needs and plant arrangements.
- Spray tray vertical dome
- Tray-only system
- Combined tray, spray and reboiling
- Horizontal dome
- Integrated feedwater storage deaerator.
Alstom‘s product ensures an obstacle free operation at both vacuum and high pressure.