Today we
will discuss about Velox boiler. velox boiler is a forced circulation water tube boiler. It is
mostly used in gas turbine. In this boiler, the velocity of flue gases is
greater than the velocity of sound, which causes more heat transfer from gas to the water,
which increases the steam generation rate. Due to this, it is most important boiler.
Velox Boiler:
Principle:
When the velocity
of the gas is greater than the speed of sound, its heat transfer rate is also
increases. So more heat is transfer from gas to water as compare when the heat
transfer at the subsonic speed. This is the basic principle of of it. This
boiler can increase the heat transfer rate or can say steam generation rate
without increasing boiler size. This is why; Velox boiler is most successful boiler in the
gas turbine industries.
Construction:
Velox boiler
is a water tube forced circulation boiler. It has a gas turbine driven air
compressor, which compresses the air. This compressed air enters into the vertical
combustion chamber, as result, high rate of heat release from the fuel, which increases
the flue gases velocity up to the sound velocity. This is a force circulation
boiler, so pump is used to circulate water inside the boiler. This boiler also
consist water and fire tube to maintain the flow of gas and water inside the
boiler. This boiler also consists other necessary mounting and accessories like
economizer, super heater, blow off valve, safety valve etc.
Working:
The Velox
boiler works as a basic heat exchanger. The working of this boiler is as follow.
The air is compressed
by air compressor driven by gas a turbine driven. This compressed
air passes from the combustion chamber, where more heat release by the fuel which
increase the velocity of the flue gases up to sound velocity. From the
bottom of combustion chamber, this flue gases pass from the fire tubes. These
fire tubes surrounded by the evaporator water tubes.
The water
from the economizer passes from the evaporator tube force by a circulating pump.
This water passes 15 - 20 time from the evaporator tube at very high speed. Due to this
high speed circulation, heat is transfer from the gases to the water at very
high rate. The mixture of water and
steam is formed which further passes from the water and steam separator.
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The steam from
the steam separator passes to the super heater and further for process work.
The remaining water in the steam separator again passes from the evaporator
tube. The flue gases
from the fire tubes send to the super heater tubes, where it increases the
steam temperature. The gas from
the super heater sends to the turbine where it rotates the gas turbine and then
passes from the economizer.
Advantages:
1. This
boiler has high heat transfer rate.
2. It has
great flexibility.
3. it is compact in design.
4. It is
easy to control. It is fully automatic.
5. It has great
thermal efficiency of about 90 - 95%.
Today we have discussed about Velox
boiler. If you have any query regarding this boiler, ask by commenting below.