Working of Benson Boiler

Benson Boiler-Parts, Construction, Working, Advantages, Disadvantages, Application, PDF

Amrit Kumar Thermal Engineering Leave a Comment

Are you looking for Benson boiler? So, Today we will study the Construction, Working, Advantages, Disadvantages, Application, PDF of Benson Boiler. Before going into details I must say, here you will get the articles of Mechanical Engineering in Brief with Some Key Points and you will get to know an enormous amount of knowledge from It. So if you find helpful this articles, please let us know in the comment box either if any correction required too, also let us know in the comment box.

What is Boiler:

  • A boiler is a closed vessel in which fluid (generally water) is heated up to high-pressure steam. The boilers are used in power plants, for the generation of steam.
  • They are mostly used in the power plants where steam turbines are used for the generation of electricity.

There are two types of boiler:

  1. Fire-tube boiler
  2. Water-tube boiler

Fire Tube Boiler:

  • Fire-tube boiler is those boiler in which the fire or hot gas is present inside the tubes and water surrounds these fire tubes.
  • Since fire is inside the tubes and hence it is named as fire tube boiler. The heat from the hot gases is conducted through the walls of the tube to the water.
  • The examples of the fire tube boiler are the simple vertical boiler, Cochran boiler, Lancashire boiler, Cornish boiler, Locomotive boiler, Scotch marine boiler, and Velcon boiler. and whereas,

Water-tube boiler:

  • Water-tube boiler is those boiler in which the water is present inside the tubes and fire or hot gases surrounds these fire tubes.
  • The examples of water tube boilers are a La-Mont boiler, Benson boiler, Stirling boiler, Babcock and Wilcox boiler, Yarrow boiler and Loeffler boiler.

Benson Boiler:

It is a water tube boiler. This is a drum-less and high-pressure boiler.

Benson Boiler Construction or Parts:

The Main Parts of Benson Boiler are:

  1. Economizer
  2. Radiant Evaporation
  3. Convection Evaporation
  4. Steam Outlet
  5. Capacity

This boiler has a unique characteristic of an absence of steam separating drum. The entire process of heating, steam generation, and superheating are done in a single continuous tube.


The feed water by means of the feed pump is circulated through the economizer tubes. Hot flue gases pass over the economizer tubes and the feed water is preheated.

Radiant evaporator:

The feed water from the economizer flows into the radiant evaporator with radiant parallel tube sections. The radiant evaporator receives heat from the burning fuel through the radiation process and the majority of water is converted into steam in it.

benson boiler

Benson boiler

Convection Evaporator:

The remaining water is evaporated in the convection evaporator, absorbing the heat from the hot gases by convection. Thus the saturated high-pressure steam at a pressure of 210 kg/ is produced.

Convection Superheater:

The saturated steam is now passed through the convection superheater where the saturated steam os superheated to 650’C. The radiant evaporator, the convection evaporator, and the convection superheater are all arranged in the path of the flue gases.

Steam outlet:

The superheated steam is supplied to the steam turbine through the steam outlet.


The capacity of Benson boiler is about 150 tonnes/hr at a pressure of 210 (kg force per square centimeter). and at a temperature of 650ºC.

Benson Boiler Working:

  • It works on the pressure of the water which is increased to the supercritical pressure (i.e. above the critical pressure of 225 bar).
  • When the pressure of water is increased to the supercritical level, the latent heat of water becomes zero and due to this, it directly changes into steam without boiling. And this prevents the formation of bubbles at tube surface.
  • In Benson Boiler, the feed pump increases the pressure of the water to the supercritical pressure and then it enters into the economizer.

Benson Boiler

  • From economizer, the water passes to the radiant heater.
  • Here the water receives the heat through radiation and partly gets
    converted into steam.
  • The temperature raises almost to the supercritical temperature.
  • After that mixture of steam and water enters into the convective evaporator where it is completely converted into steam and may superheat to some degree.
  • Finally, it is passed through the superheater to obtained the desired superheated steam.
  • This superheated steam is then used by turbines or engine to produce the electricity.

Benson Boiler Advantages:

  1. It is lightweight and it has no drum. For this reason, it is lighter than another boiler.
  2. It starting time is less than other boiler and
  3. it has up to 90 percent thermal efficiency.

Benson Boiler Disadvantages:

  1. Due to supercritical types of boiler, its controlling need to monitor every time for preventing an explosion.
  2. Boiler control for the variable load is difficult.

Benson Boiler Application:

  1. This supercritical boiler is used in different industries to generate steam for the production of electricity or mechanical power.
  2. The average operating pressure, temperature, and capacity of Benson boiler is 650 degree Celsius, 250 bar, and 135 tonnes/h.

Benson Boiler Features:

  • In Benson boiler, there are no drums, so the total weight of Benson boiler is 20% less than the other boilers. that reduces the cost of the boilers.
  • Because of no drums are used in this boiler, the transfer of the Benson boiler parts is easy. chances of all the parts may be carried to the site, without pre-assembly.
  • One more feature this is a once-through boiler and the feedwater entering at one end is discharged as superheated steam at the other end.

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About the Author

Amrit Kumar

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Amrit is a Co-founder of Learn Mechanical Portal (Previously owned ""). He completed his diploma in Mechanical Engineering from Acharya Polytechnic Bangalore and also completed his B-Tech from Delhi. Amrit is now preparing for Govt. exams. If you need help, you can ask him regarding any suggestions in the mechanical engineering field. He loves to meet new people.

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