Working Principle
The pressure of the water is increased to the supercritical pressure (above critical pressure of 225 bar). Once the pressure of water is increased to the super critical level, the latent heat of water becomes zero and because of this, it directly changes into steam while not boiling. It prevents the bubbles formation at tube surface.
Benson Boiler - Construction
Air Pre-heater :
It preheats the air before getting in the furnace. Burning efficiency/potency of the fuel is increased by this pre-heated air.
Super heater :
Heats the water with radiation produced by the burnt fuel. It raises the temperature to supercritical temperature.
Economizer :
It heats the water to a certain temperature.
Evaporator :
It evaporates the superheated water and converts them into steam. It will thus by the convection mode of heat transfer to the water from the hot flue gases.
Super heater :
It superheats the steam to the required temperature.
Furnace :
It is the place wherever the fuel is burnt.
Feed pump :
It is used to supply the water inside the boiler at supercritical pressure of 225 bars.
Working :
In Benson Boiler, the feed pump will increases the pressure of the water to the supercritical pressure and then it getting in the economizer.
The water passes to the radiant heater through economizer. Here the water receives the heat through radiation and partially gets converted into steam.
The temperature raises nearly to the supercritical temperature. Then the mixture of steam and water enters into convective evaporator.
Now it is completely converted into steam.
Finally it is passed through the super heater to obtained the desired superheated steam. This superheated steam is then used by turbines/engines to produce the electricity.
Advantages :
Light in weight
Small area is enough for erection.
Easy transportation.
Achieve thermal efficiency upto 90%.
This boiler started within 15minutes.
Avoid bubble formation due to super critical pressure of water.
Applications :
This supercritical boiler is used in different industries to generate steam for the production of electricity or mechanical power.
The average operating pressure, temperature and capacity of Benson boiler is 650 degree Celsius, 250 bar and 135 tones/h.
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