Benson Boiler: Working, Construction, Parts, & Applications

The boilers are most commonly used in various household and industrial applications. They usually use to transform water into steam. Benson boiler is one of the most famous types of boilers. This article deeply describes the Benson boiler working, types, and applications.

What is Benson Boiler?

Benson Boiler is a forced circulation, drumless, high-pressure steam boiler used in power plants. It is a type of water tube boiler. Mark Benson created this boiler in the 20th century.  

Benson Boiler works on the principle of forced circulation of water through a series of tubes. It is a supercritical boiler. This boiler works on supercritical pressure.

When water is pressurized up to supercritical pressure, no surface bubbles appear on the water surface. This is because water and steam have the same density at supercritical pressure. Therefore, bubbles don’t produce. To distinguish air bubbles from water, there is no need for an air separator drum like a drum in the Loeffler boiler.

Benson Boiler

In the field of thermodynamics, critical pressure is considered the pressure at which the gas and liquid phases can coexist at the equilibrium phase.

Mark Benson was a German engineer who first pitched the idea of a supercritical boiler in which water is compressed at supercritical pressure before heating it into the boiler. Due to this process, the water’s latent heat becomes zero. The water suddenly converts into a steam phase without the formation of bubbles just after the latent heat of the water shrinks to zero.

The main advantage of the Benson Boiler is that it doesn’t contain a separate steam drum, which helps to reduce the overall difficulty and weight of the boiler.

Working of Benson Boiler

A Benson boiler works in the following way:

Working of Benson Boiler

  • Air is taken in from the atmosphere using a blower. The main function of the blower is to transfer the air into the preheater at a higher pressure and speed.
  • The preheater raises the temperature of the air as it receives it, turning it into hot gases. After this preheating operation, the preheater delivers the final hot gases into the furnace.
  • The water pressure is increased by a feed pump to supercritical pressure and then sent to the economizer. The economizer uses the heat from the hot flue gases to warm the water. In this way, the boiler’s efficiency is increased via the economizer.
  • The water enters the radiant superheater after going through the economizer. The water temperature rises to a supercritical temperature as a result. This superheater transfers the heat from the combustion chamber to water. The water in this process partially maintains its liquid condition and partially turns into steam. The convective superheater receives this combination of water and steam.
  • Once the steam and water mixture enters the convective superheater, it is completely transformed into superheated steam.
  • When the water completely transforms into steam, it is sent to the steam turbine to generate energy.
  • Due to the lack of a water and steam separation drum, this type of water boiler is also known as a lightweight boiler.
  • The thermal efficiency of the Benson boiler is up to 90%.
  • It can generate steam at a rate of up to 135 tons per hour and at a pressure of 250 bars.

Construction of Benson Boiler

Benson Chamber is one of the largest components of the Benson Boiler. There are additional pieces maintained inside this compartment.

The boiler also has an air preheater that is attached to the blower. There is a feed pump underneath the air preheater. Water is transferred to the economizer via a feed pump that is attached to it.

This boiler also contains a radiant superheater. It is coupled with the economizer. The radiant superheater is installed at the bases of the chamber. The convective superheater is linked to the radiant superheater, and the turbine is then connected. The steam strikes the blades of the turbine which in result produces electricity.

Parts of Benson Boiler

The following are the parts of the Benson boiler:

  • Benson Chamber
  • Throttle Valve
  • Blower
  • Furnace
  • Water Feed Pump
  • Economizer
  • Air Preheater
  • Radiant Superheater
  • Convection Superheater
  • Convection Evaporator
  • Chimney

1) Benson Chamber

This chamber is an external part of the boiler. It is the place where all the other components of the boiler are placed.

2) Throttle Valve

These valves have the function of storing and regulating the flow of steam.

3) Blower

We are aware that a blower’s primary function is to blow air rapidly and in a certain direction. The blower and air preheater are coupled, and their functions are identical. The air preheater receives air from the blower, which heats the air.

4) Furnace

The furnace is one of the most important parts of the Benson boiler. It is the area where fuel is burned. It has the maximum highest temperature. Only from this point, the flue gases are sent to the tube and other locations.

5) Water Feed Pump

The feed pump’s primary function is to transfer hot water from the hot well to the boiler at 225 bars of supercritical pressure. This pump uses a piston (in the case of a reciprocating pump) or an impeller (in the case of a centrifugal pump) to boost the water’s pressure before sending it to the boiler.

The feed pumps have multiple types, such as centrifugal pumps, reciprocating pumps, or diaphragm pumps.

6) Economizer

Before the water enters the boiler, it is heated in the economizer. Initially, the feed pump feeds water into the economizer, which then raises the water’s temperature by heating it.

A centrifugal pump is usually utilized to supply the economizer’s hot water to the boiler after the heating process. It also helps to improve the performance of your boiler.

7) Air Preheater

The air preheater’s primary function is to warm the air. It receives heat from the furnace.

When the blower supplies the air into the preheater, it increases the air temperature by heating process and turns it into hot flow gases. It helps to improve the fuel’s thermal efficiency.

8) Radiant Superheater

The main function of the radiant superheater is to help in heating the water by emitting radiation from the burned fuel and increasing the water’s temperature to a supercritical level.

This part of the Benson boiler is linked to the convective superheater, which is then attached to the turbine from where electrical power is generated.

9) Convection Superheater

The main function of the conviction superheater is to heat the steam to 650 degrees Celsius, which is the ideal temperature.

10) Convection Evaporator

The water entirely evaporates in this evaporator. In other words, the convection evaporator turns the superheated water into steam by evaporating it. In the convection evaporator process, heat is transferred from flue gases to water through the convection mechanism.

11) Chimney

The chimney expels the burnt gases that have now turned into smoke to the environment.

Read More: Boiler Mountings and Accessories

Advantages of Benson Boiler

  • Because there is no steam drum, the Benson boiler is less expensive and produces greater power pressure, which means there is no pressure threshold for reaching supercritical pressure.
  • Achieving high pressure prevents bubbles from accumulating in the tubes and raises the maximum heat rate, which prevents a decrease in the boiler’s power efficiency due to the presence of bubbles.
  • It is more lightweight than conventional boilers.
  • The boiler is easy to carry and runs efficiently.
  • The transportation of this boiler is easy.
  • Benson Boilers operate at supercritical pressure, which allows them to achieve higher thermal efficiency and produce more electricity per unit of fuel.
  • Tiny tubes of smaller diameter make up the boiler. It aids in the creation of tiny explosive danger risk circumstances.
  • These boilers have the ability to burn different types of fuels, such as natural gas, oil, and coal. These boilers may also be installed with advanced pollution control technologies to lower the emission rate of injurious exhaust gases such as sulfur dioxide and nitrogen oxides.

Disadvantages of Benson Boiler

  • Overheating of the tubes might result in inadequate water delivery.
  • Little storage capacity necessitates precise coordination between steam, feedwater, and feed input.
  • If the water present is polluted with salts and solids in tubes accompanying the evaporation process will cause damage. The boiler tubes may suffer serious damage and obstruction as a result.
  • You can have some issues and challenges while attempting to manage the boiler for fluctuating loads.
  • Throughout the length of each movement, it needs to be continuously inspected to avoid an explosion because of the existence of supercritical pressure.

Benson Boiler Applications

  • The high-pressure supercritical Benson boiler is used in a wide range of industries to provide steam and power.
  • They are ideal in large-scale power plants where high-pressure steam is needed to run turbines and produce electricity.
  • The boiler can produce roughly 135 tons of heat per hour at an average optimal pressure of 250 bar, 50 degrees Celsius.

FAQ Section

What is the thermal efficiency of the Benson Boiler?

The Benson boiler has up to 90% thermal efficiency of the

What are the features of the Benson Boiler?

  • It doesn’t have a separate drum. Therefore, it has a lower weight than the conventional boiler.
  • It has a low cost.
  • The boiler is easy to carry and runs efficiently.
  • The transportation of this boiler is easy.
  • These boilers have the ability to burn different fuels, such as gas, oil, or coal.

Is the Benson boiler a supercritical boiler?

It is a supercritical, drumless, high-pressure, water tube boiler with forced circulation.

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