Cornish Boiler: Parts and Construction, Working, Applications and More

Today I am going to discuss Cornish Boiler.

If you are looking for a short and sweet explanation of this boiler, then you landed on the right runway, here you will know about this boiler, from scratch to end.

Hence, I invite you to join the swirl of this knowledgeable journey with me and I hope this will end your search here.

So, without taking too much time, let me start this knowledgeable journey with you.

So, here we go…

Cornish Boiler-

Cornish Boiler is a fire tube, horizontal, internally fired, natural circulation boiler just like Lancashire boiler except having a single large fire tube instead of two fire tube in Lancashire boiler.

Firstly, This boiler was initiated by Richard Trevithick and installed at Dolcoath mine in 1812.

Cornish boiler can produce steam at the rate of 6500kg/hr with a maximum steam pressure of 11bar.

Parts and construction of Cornish Boiler-

Here are some main parts and its construction-

  1. Manhole
  2. Safety Valve
  3. Flue tube
  4. Grate
  5. Blow-off cock
  6. Stop valve


Manhole is basically used for cleaning and maintenance of the boiler, located top of the boiler.

Safety Valve-

This device is used to protect the boiler from excess steam generation and explosion, located top of the boiler.

Flue tube-

A flue tube is used to supply the solid fuel into the boiler located front side of the boiler.


As you know, the grate is made of from cast steel bar and basically used to hold the solid fuel located inside the flue tube or firebox, located in front of the boiler.

Blow-off cock-

This device is used to drain out the boiler water when needed. It is located at the front bottom side of the boiler.

Stop valve-

The function of the stop valve is to regulate and supply the saturated steam in further directions and it is located at the top of the boiler.


Now let’s talk about the placement of these parts of this boiler-

First of all the manhole is located at the top of the boiler with a safety valve also located at the top(shown in the figure above). Here the flue tube is located at the front side of the boiler and then grate is also located at the same as flue tube.

Now its time for Blow-off cock and stop valve, One is located at the front bottom side of the boiler and other is located top of this boiler.

Working of Cornish Boiler-

When solid fuel or coal is burnt inside the fire door, these hot gases or flue gases will generate and this will travel into a single large fire tube.

This fire tube is surrounded by the water and hence these hot gases will exchange heat with water, this exchange of this heat will cause heat up the water.

Heated water will now convert into steam after reaching the boiling point.

This generated and saturated steam will subside at the top of the boiler shell.

Now, again hot gases will travel from the fire tube and exits from the side flue corner and again heat up the water from the side to raise the efficiency of the boiler and maximum utilization of the hot gases, as you can see in the diagram.

Again these hot gases travel into the bottom flue corner to exit from the chimney.

Thus, generated steam will be now go to the stop valve, where this saturated steam will further sent to the superheater to superheat the steam and further taken out for use.

This is how this works.

Advantages of Cornish Boiler-

Here are some advantages of this boiler-

  1. Simple Design
  2. High thermal efficiency
  3. Flexible and Portable
  4. Economical

Disadvantages of Cornish Boiler-

Here are some disadvantages of this boiler-

  1. Low-pressure boiler
  2. Large spacing required
  3. low steam rate production

Applications of Cornish Boiler-

Here are some disadvantages of this boiler-

  1. sugar mills
  2. chemical industries
  3. Steam turbine
  4. Marines
  5. Thermal Power generation

That’s it for Cornish Boiler. I hope you liked the way it was presented to you and it resolved your query in a short and sweet manner.

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Before you leave, here are some related questions and its answer, you should have a look for while-


What is the efficiency of the cornish boiler?

It has a steam capacity of 6500kg/hr with a maximum working pressure of 11bar. This is the overall efficiency of the cornish boiler.

The number of water tubes in a cornish boiler?

There is a single large fire tube in the cornish boiler. There is no water tube present in this boiler.

The cornish boiler is an example of which type of boiler?

Cornish boiler is a suitable example of a fire tube boiler.

How many fire tubes are there in the Cornish boiler?

There is only one fire tube in this boiler that is internally fired.

What is the steam capacity of a Cornish boiler?

The steam capacity of this boiler is 6500kg/h.

Is Cornish boiler is a low-pressure boiler?

Yes, this boiler is a low-pressure boiler but it has high thermal efficiency.

What is the pH value of water permissible for the boiler?

The pH value of water permissible for the boiler ranges from 8.4 to 8.5pH.

What chemicals are used in boilers?

Sodium hydroxide and potassium hydroxide, are the chemicals which used in boilers.

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