Cornish Boiler: Definition, Parts, Working, Advantages, Applications [PDF]

After Cochran, Locomotive, Scotch marine boiler, a Cornish boiler is another type of fire tube boiler. This type of boiler works on very limited pressure which is up to only 20 bar. It has a long horizontal cylinder with a single large flue containing the fire.

Definition of Cornish Boiler

Cornish boiler is a fire tube boiler whose work is to produce steam by the burning of fuel(coal) to be used in the steam turbine, textile or sugar mill industry, etc.

Construction or Parts of Cornish Boiler

A Cornish Boiler consists of several parts which are as follows:

  • Shell
  • Grate
  • Furnace
  • Combustion chamber
  • Chimney
  • Smokebox
  • Water level indicator
  • Safety Valve
  • Man Hole
  • Stop Valve
  • Blow off valve


A shell contains water inside it as well as a tube. The transfer of heat between water takes place in the shell. Also the shell is designed in such a way that it covers all the components of the boiler. It is also called as the main body.


It is a door from which the fuel is provided for burning and generating heat. The grate is located at the bottom of the furnace.


A furnace works like a mediator because it is connected between the fire tube and the combustion chamber. Here fuel burns and produces Heat.

Combustion chamber:

In the combustion chamber the fuel burns and produces heat which is then supplied to the tube where water is surrounded. The combustion chamber is connected to the furnace.

Ash pit:

The ash of fuel is completely burned and it has no use inside the boiler.


The chimney is present for releasing the exhaust gases to the atmosphere.


The smokebox is provided to collect the smoke and further send it to the chimney.

Water level indicator:

This is an instrument which gives the detail of the water level of the boiler. This also works when water exceeds the limit.

Safety Valve:

The safety valve is another type of instrument which is used for safety purpose. This also works when no other indicators work.

Man Hole:

It is the main hole from which an engineer will enter when any components inside the boiler get damage and replace it.

Stop Valve:

The stop valve is also used for regulating the control of things.

Blow off valve:

A blow of valve is used to clean the boiler by discharging the water and sediments from the bottom of the boiler

Working Principle of Cornish Boiler:

Cornish Boiler
Cornish Boiler diagram
Cornish Boilers
Cornish Boiler

The working substance here is Coal. At the grate, the fuel which is coal is provided which is then sent to the furnace. Here we burn the fuel by providing some amount of fire to it. Burning of coal produces the heat which is then sent to the tube surrounded by water. With the use of an instrument called water level indicator we measure the level of water. Now tube has sufficient heat so that the water gets heated. The water first converts into saturated steam and then it is further heated and converts into superheated steam which is now working steam.

The steam can be further be used for different purposes. Meanwhile here the burning coal ash comes to the ash pit and from here it comes to the smokebox where the gas will release through the chimney to the environment. We can then extract the ash from the system and clean it.

Advantages of Cornish Boiler:

The advantages of a Cornish boiler are as follows:

  • The design is simple and easy.
  • The construction is easy and compact.
  • It is a portable type of boiler.
  • The maintenance cost is low.
  • It can handle load fluctuation to some extent.

Disadvantages of Cornish Boiler:

These are some disadvantages of Cornish Boiler which are as follows:

  • It has a low production steam rate which is around 1350 kg/hour.
  • The pressure is low as compared to other boilers which are 12-13 bar.

Applications of Cornish Boiler:

Application of the Cornish boiler are as follows:

  • It is used in several industries like sugar, mill, chemical, and other more industry.
  • It is also used to run the steam turbines.
  • Cornish Boiler used in marines.


What is the cornish boiler?

It is another type of fire tube boiler. It produces steam by burning fuel which is coal.

What is a fire tube boiler?

There are mainly two types of boiler.
1. Water-tube boiler (In this type the water is flowing inside the tube and hot flue gases surround them)
2. Fire-tube boiler (The hot flue gases flows inside the tube and water surrounds them)

What is the construction of the Cornish boiler?

A Cornish boiler consists of:
1. Shell
2. Grate
3. Furnace
4. Combustion chamber
5. Chimney
6. Smokebox
7. Water level indicator
8. Safety Valve
9. Man Hole
10. Stop Valve
11. Blow off valve

What are the different types of fire tube boiler?

Following are the different types of boilers:

Cornish boiler
Cochran boiler
Lancashire boiler
Locomotive boiler
Scotch marine boiler
Horizontal return tubular boiler
Vertical fire-tube boiler

What are the different types of water tube boiler?

Following are the different types of water tube boilers:

Lamont Boiler
Loeffler boiler and
Yarrow boiler.
Benson Boiler
Babcock and Wilcox Boiler

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