Make-up water is usually fully saturated with oxygen (see diagram).
For make-up water with oxygen content of 9000 ppb (9 mg/lit) at deaerator inlet,
the oxygen content at the outlet of 5 to 7 ppb (0.005 to 0.007 mg/lit) should be achieved.
For a lower mass flow rate of make-up the water can be sprayed to the cycle in the condenser neck.
for Make-up Water and Condensate
The deaerator is arranged as cylindrical dome over FWST or as separate deaerator.
The mixture of Make-up water and condensate is sprayed at the top of the deaerator (Fig. 007).
By means of a distributor the sprayed water is distributed across the dome cross-section.
The water trickles down through the mass transfer packing elements and forming a large
interfacial area between the water and the surrounding steam phase. A venting system
extracts all gases from the vapor phase. The freed non-condensable gases is discharged to
atmosphere or to the condenser via the vent openings at deaerator top.
Since the packing elements are expensive, the packing deaerator is used for deaeration of
water under extreme parameters (high oxygen content and low pressure).
The disadvantage of this deaerator type (especially in case of vacuum deaeration) that a
large packing diameter is necessary because of the large volume flow of the heating steam.
The large packing volume leads to higher deaerator costs.
TPT Packing Deaerator
for make-up water and condensate
High performance deaerator for high make-up flow rate and vacuum pressure
The Make-up water is sprayed in a chamber at the top of the deaerator dome. During direct
introduction of steam to the upper chamber the water is heated and partly deaerated.
The heated water flows downward to the distributor and distributed across the dome cross-section
The condensate can be introduced into the dome by spray nozzles above the Packing or by a
spraying valve above the distributor. The make-up water and the condensate trickle down through
the packing elements in counter flow to the second steam flow part.
The steam flow through the packing is reduced and thus arises a small packing diameter.
The packing diameter D is laid out so that the flood limit is not exceeded. The calculation will be
determined for the worst operation case and from the water and steam load capacities of the
By means of a venting system with a venting condenser the gases is extracted from the deaerator
through several venting stages. A small bypass make-up flow is selected, which is sprayed by a
small nozzle into the vent condenser. By means of openings at the top of the upper chamber and
the top of the packing chamber the steam/air flows (Vent 1 and Vent 2) are throttled to the vent
condenser. The throttle organs of the vent lines 1 and 2 are adjusted in such a way that the
pressure Pv of the vent condenser and the desired steam/air flows (Vent 1 and Vent 2) results in.
The non-condensable gases (Vent Mv) is discharged from the vent condenser via a throttle organ
to the condenser.
Special Packing Deaerators for CCPP:
Patent: EP 077500: Packing Deaerator with counter-flow
Patent: US 5203286: Packing Deaerator with parallel/counter-flow
Spray type deaerator in FWST
The deaeration occurs by blowing steam through the feedwater in FWST.
This deaeration can be used as final or after deaeration step. The spray type deaerator has
the disadvantage of steam pressure loss which reduces the saturation temperature.
TPT can help you in deaerator questions like:
- New deaeration concepts for normal and special cases
- Deaerator design
- Failure analysis
- Improvement of deaerator design
- Solution of deaerator problems