DEAERATOR
122, Cheoyongsaneop 3-gil, Cheongnyang-myeon, Ulju-gun, Ulsan, 689-892, Korea
TEL : +82-52-237-2213 FAX : + 82-52-237-2235
E-mail : [email protected] Website : http://www.powerhx.com
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www.powerhx.com
DEAERATOR
General Principle of deaerating[ Typical Deaerator Connections and Accessories ]
Classification by Shape
The removal of dissolved gases from boiler feedwater
is an essential process in a steam system. The presence
of dissolved oxygen in feedwater causes rapid localized
corrosion in boiler tubes. Carbon dioxide will dissolve in
water, resulting in low pH levels and the production of
corrosive carbonic acid. Low pH levels in feedwater cause
severe acid attack throughout the boiler system. While
dissolved gases and low pH levels in the feedwater can be
controlled or removed by the addition of chemicals, it is
more economical and thermally efficient to remove these
gases mechanically. This mechanical process is known
as deaeration and will increase the life of a steam system
dramatically.
Deaeration is based on two scientific principles. The first
principle can be described by Henry’s Law. Henry’s Law
asserts that gas solubility in a solution decreases as the
gas partial pressure above the solution decreases. The
second scientific principle that governs deaeration is the
relationship between gas solubility and temperature.
Briefly explained, gas solubility in a solution decreases
as the temperature of the solution rises and approaches
saturation temperature. A deaerator utilizes both of these
natural processes to remove dissolved oxygen, carbon
dioxide and other non-condensible gases from boiler
feedwater.
The feedwater is sprayed in thin films into a steam
atmosphere allowing it to become quickly heated to
saturation. Spraying feedwater in thin films increases
the surface area of the liquid in contact with the steam,
which results in more rapid oxygen removal and lower gas
concentrations. This process reduces the solubility of all
dissolved gases and removes them from the feedwater.
The liberated gases are then vented from the deaerator.
This system reduces dissolved oxygen concentration to less
than 0.005 cc/liter (7 ppb) and completely eliminates the
carbon dioxide concentration.
Ⓐ Water(Condensate) inlet
Ⓑ Spray Valve
Ⓒ Vent Orifice
Ⓓ Vent Nozzle
Ⓔ Relief Valve
Ⓕ Tray Box
Ⓖ Pressure Gauge
Ⓗ Level Gauge
Ⓘ Man Hole
Ⓙ Drain Nozzle
Ⓚ Tank Saddle
Ⓛ Water Outlet
Ⓜ Sparger Pipe
Ⓝ Deaerator Saddle
Ⓞ Downcomer
Ⓟ Equalizer
Ⓠ OverFlow Nozzle
Ⓡ Steam Inlet
Dissolved oxygen and carbon dioxide in the Boiler Feed
Water of industrial steam generators that are used in
electricity plants and incineration plants, causes the
corrosion of the Boiler Feed Water Container, which
significantly affects the durability of pipes and all the
equipment. To eliminate the dissolved oxygen and carbon
dioxide, installing a deaerator is essential. This deaerator
can also preheat the Boiler Feed Water up to the necessary
temperature as a Feed Water Heater, which helps increase
the efficiency of the equipment.
Generally, the Deaerator is divided into two parts; the top,
deaerating Heater (for degassing) and the bottom, Storage
Section. Due to their different shapes, the deaerating
Heater is classified into Vertical deaerator type, and
Horizontal deaerator type.
Storage Tank
Storage Tank
Storage Tank
Storage Tank
>> Vertical deaerator with horizontal storage tank - Applicable to small and medium capacity(up to 220 ton/hr)
Undeaerated Water Non-Condensibles(Vented)
SteamDeaerated Water
[ O2 concentration in saturated demi-water ]
Dis
solv
ed
Oxyg
en
(in
pp
m)
Water Temperature (in Deg C)
0 10 20 30 40 50 60 70 80 90 100
14
12
10
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4
2
0
A thermal power station is a power plant in which
heat energy is converted to electric power. The turbine
is steam-driven. Water is heated, turns into steam
and spins a steam turbine which drives an electrical
generator. After it passes through the turbine, the steam
is condensed in a condenser and recycled to where it was
heated; The greatest variation in the design of thermal
power stations is due to the different heat sources, fossil
fuel dominates here, although nuclear heat energy and
solar heat energy are also used. Some prefer to use the
term energy center because such facilities convert forms
of heat energy into electrical energy. Certain thermal
power plants also are designed to produce heat energy
for industrial purposes of district heating, or desalination
of water, in addition to generating electrical power.
[ Large Spray Valve Performance Curve ]
Inle
t Fl
ow
Ra
te(t
/h)
△P Pressure difference
0
150
140
130
120
110
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90
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Va
lve
flo
w V
elo
city
(m/s
ec)
Valve N/Z flow Velocity
Ex) flow rate 50t/h flow velocity 8.4m/s valve lift 5.9mm △P 3.7mAg
Va
lve
lif
t
Valve lift
Inlet FlowRate(t/h)
>> Horizontal deaerator with horizontal storage tank - Applicable to large capacity (over 220 ton/hr)
Enclosure wall
[ Structure of spray nozzle, collecting (water) and distributing tub and tray ]
[ Power plant process diagram ]