General
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.
Classification
by Shape
Classification by Shape
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.
Vertical deaerator with horizontal storage tank
- Applicable to small and medium capacity(up to 220 ton/hr)
Horizontal deaerator with horizontal storage tank
- Applicable to large capacity (over 220 ton/hr)
Principle of
deaerating
Principle of deaerating
Degassing is based on three scientific principles.
First, Henry's law states that the solubility of the gas is proportional to
the partial pressure of the gas which is in equilibrium with the solvent.
The second is that the pressure of the mixed gas is equal to the sum of the
pressures of the individual components when two or more different gases are
mixed in a single container by the law of partial pressure of the Dalton.
The last is the relationship between gas solubility and temperature.
Briefly, the gas solubility of a solution decreases with increasing
temperature and close to saturation temperature.
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.
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.