In this article, you’ll learn what is Benson boiler. Its diagram, parts, working, advantages, and applications all are explained with pictures.
Benson Boiler
The Benson boiler is a high-pressure, drum less, water tube steam boiler using forced circulation. In this boiler, the feed water enters at one and discharges superheated steam at the other end.
The feed pump increases the pressure of water to supercritical pressure (i.e. above the critical pressure of 225 bar) and thus the water directly transforms into steam without boiling.
A Benson boiler produces steam at supercritical pressure, pressure, and temperature above the critical point of water, resulting in improved thermodynamic efficiency and power generation. It is one of the most advanced high-pressure boilers available.
Parts of Benson Boiler
The following are the construction parts of a Benson boiler:
- Furnace
- Feed pump
- Steam outlet pipe
- Air Pre-heater
- Economiser
- Radiant superheater
- Convection superheater
- Convection evaporator
#1. Furnace.
It is the space, above the grate and below the boiler shell, in which the fuel is actually burnt. The furnace is also called a firebox.
#2. Feed Pump.
It is a boiler accessory needed to force the feed water at high pressure into the boiler.
#3. Steam Outlet Pipe.
The superheated steam is supplied to the steam turbine by a steam outlet pipe.
#4. Air Pre-heater.
The air preheater is a necessary accessory that develops the heat in the exhaust gases by heating the air supplied to the furnace of the boiler. The Preheated air improves the thermal efficiency of the fuel.
#5. Economizer.
In economizer, burning the feed water to a certain temperature. It makes the recovery of heat in the exhaust gases. Economizer improves the overall efficiency of the boiler by reducing fuel consumption.
#6. Radiant Super heater.
It is a superheater that heats water from radiation generated by burnt fuel. This increases the temperature to supercritical temperature.
#7. Convection Super heater.
The convection super heater superheats the steam to the desired temperature (about 650° C).
#8. Convection Evaporator.
In a convection evaporator, it evaporates superheated water and transforms it into steam. It does this by the convection method of heat transfer from hot exhaust gases to water.
Working of Benson Boiler
The diagrammatic sketch of a Benson boiler is shown in the figure. It is a water tube boiler, which works on the principle of the critical pressure of water. Critical pressure is the pressure at which the water and gas states are in equilibrium.
The feedwater passes through the economizer to the water-cooled walls of the furnace. The water receives heat by radiation and the temperature increases to nearly critical temperature.
It then enters the evaporator and may get superheated to some degree. Finally, it is transferred through the super heater to achieve the desired superheated steam.
This boiler is also known as a lightweight boiler as there is no large water and steam drum. A thermal efficiency of up to 90% may be achieved by this boiler.
The average working pressure and capacity of this type of boiler is 250 bar and 135 tons/hour. It can be within 15 minutes.
Features of Benson Boiler
The following are the important features of the Benson boiler:
- When steam and water equalize in density, bubbles cannot form when boiler pressure is raised to the critical level of 225 atm.
- Benson boilers do not require expansion joints due to their welded pipes, which makes installation easier and saves time.
- Components of the Benson boiler are easy to carry because they don’t have drums, so most pieces can be shipped without needing to be assembled.
- Benson boilers are not limited by space constraints, allowing them to be installed in comparatively small places.
- They provide improved protection for the furnace wall by the use of closely spaced, small-diameter tubes.
- The Benson boiler includes the superheater in the forced circulation system, which eliminates the need for specific starting arrangements.
- Benson boilers can be quickly started because of their welded joints.
- The most efficient way to operate Benson boilers is to maintain the desired temperature levels while regulating pressure and temperature at overloads and partial loads.
- Because Benson boilers can successfully adjust to sudden changes in load, they are perfect for grid power stations due to their insensitivity to load swings.
- Benson boilers are much less likely to explode since they are mostly made of tiny-diameter tubes and have a minimal amount of storage space.
Advantages of Benson Boiler
The following are the advantages of the Benson boiler:
- The cost of the boiler is low because there is no water and steam drum.
- There is no pressure limit, therefore supercritical pressure may be used.
- The high pressure avoids the bubble formation in the tubes which increases the heat transfer rate.
- It is a lightweight boiler.
- The boiler can be started within 15 minutes.
Disadvantages of Benson Boiler
The following are the disadvantages of the Benson boiler:
- Due to the supercritical type of boiler, its control requires to be inspected every time to prevent an explosion.
- This Boiler control is difficult for variable loads.
Application of Benson Boiler
The Following are the applications of Benson Boiler:
- To generate steam efficiently, Benson boilers are widely utilized in modern power plants.
- They are used in both fossil fuel-fired and nuclear power facilities.
- In combined cycle power plants, Benson boilers are used to maximize energy conversion.
- They are essential to industrial operations that need supercritical and high-pressure steam.
- Thermal desalination plants use Benson boilers to turn seawater into fresh water.
- They are used in cogeneration systems to generate power and heat simultaneously.