Locomotive Boiler: Working, Parts, Applications, & Construction

The boilers are used all over the world for heating different fluids, especially water. This heated water creates steam that performs suitable work. The steam conditions change with temperature changes. There are multiple types of boilers, and a locomotive boiler is one of them. The locomotive boiler is used in the locomotive engines where it generates steam to power the vehicle’s steam engine. In the most modern models, the vehicles are driven by an electric engine or diesel engine. This article mainly explains the locomotive boiler working, parts, and applications.  

What is Locomotive Boiler?

A locomotive boiler is a natural circulation, multi-tubular, mobile, horizontal drum, forced circulation, artificial draft, medium pressure, and internally fired fire tube boiler.

Locomotive boilers are most commonly used to power ships and locomotive engines. A locomotive boiler is a mobile boiler with high steam generation. In 1802, Richard Trevithick designed the first locomotive boiler. 

It has natural circulation. It has a horizontal shell made up of several fire tubes.

locomotive boiler

This type of boiler has a stake for the removal of flue gases instead of a chimney. The Locomotive boiler is used solid fuels for heating the flue gases. It is a portable boiler (i.e., it can easily transfer from one place to another). 

Working of Locomotive Boiler

Many working steps of the locomotive boiler are similar as the Lancashire boiler, but there is a little bit of difference. A locomotive boiler works in the same way:

Locomotive boiler working

First of all, the boiler grate burns solid fuel (i.e., coal). Due to the burning process of solid fuels, hot gases (or flue gases) are produced, which start flowing in the fire tubes.

As the flue gases flow through the flue tubes, they transfer their heat to the flue tubes. The boiler has a fire brick arch which uses to direct the flue gases toward the flue tubes and stop the entry of solid fuel particles into the fire tube.

The boiler water surrounds the flue tubes. The heat of these flue gases is transferred to the water due to that water starts converting into steam. After transferring heat to the water, the burnt flue gases leave the boiler through the chimney.

This process continues until the whole water is converted into steam.

The produced steam is in saturated form, and a steam dome uses to collect this steam. This collected steam may be directly utilized to run the steam engine, or firstly you may convert it into a superheated state and then use it.

To convert the steam into the superheated state, a regulator uses to regulate the steam available in the dome and ensure the entry of saturated steam into the steam pipes.

By passing through steam pipes, the saturated steam enters the superheater.  The superheater transforms the saturated steam into supersaturated steam and sends this steam into a cylinder. The cylinder has a piston that moves up and down. This piston connects with steam engine wheels.

As the superheated steam strikes the piston, the piston starts moving inside the cylinder.  When the piston moves, it further moves the steam engine wheels due to that wheel starts reciprocating.

As the useless gases and smoke pass through the fire tubes, they enter the smokebox. The useless steam pushes the smoke and burnt gases of the smokebox and discharges them from the chimney of the boiler.

Read More: Working of Lancashire Boiler

Components of Locomotive Boiler

The locomotive boiler has the following major components:

  1. Superheater
  2. Boiler shell
  3. Fire brick arch
  4. Grate
  5. Ashpit
  6. Fire tubes
  7. Fire hole
  8. Deflector
  9. Blast pipe
  10. Smoke box
  11. Smoke box door
  12. Firebox
  13. Chimny 
  14. Super heater head
  15. Steam dome
  16. Super heater tubes
  17. Safety valves
  18. Steam regulator 
  19. Blow off cock 
  20. Exhaust steam pipe
  21. Manhole
  22. Pressure guage 
  23. Water level indicator

Parts of Locomotive boiler

1) Boiler Shell

The boiler shell is the outer housing of the boiler. All the internal parts of the boiler are present in the boiler shell. It provides safety to the internal parts and prevents them from any damage due to any heavy load.

2) Superheater

This is the most vital component of the locomotive boiler. The superheater increases the temperature of the saturated steam and converts it into a superheated state. After converting into the superheated state, it sends the steam into the steam engine.

Read More: Different Types of Boilers

3) Fire Tubes

The flue gases move inside the fire tubes. These tubes are surrounded by water. As the flue gases flow, they transfer their heat to fire tubes, and these tubes further transfer heat to the surrounding water.

4) Ashpan or Ashpit

The ashpan uses to collect the ash of the combusted coal. This unit is installed under the grate. The sheet steel uses for the construction of the ashpan.

 5) Grate

The grate is the place where solid fuel is combusted. It is a series of parallel bars under the firebox for holding the coal fuel. The grates are made in sections, and each section has three to four bars. These bars are linked with a lever through rods. This lever moves forward and backward to move the bar, shake ash, and remove ash from the fire.

The cast iron is used for the construction of the grate. The boiler has spaced between the grate for the easy burning and passing of air.

6) Fire Brick Arch

The fire brick arch is installed on the gate. It stops the entry of combusted fuel particles, dust, and ash into the fire tube. This arch also ensures the entry of the flue gases into the fire tube.

It has a very high temperature. This unit of the boiler works as a mixer for combustion products and air. It also acts as a reflector for radiant heat from leaking gas and fire.

7) Deflector

When the fuel is combusted, a deflector diverts the generated flue gases into the fire tube. It is made of an iron plate. It installs at an angle in part of the front edge of the chimney, which diverts the combustion gases downwards before they enter the chimney and greatly balances the ventilation of the various flue pipes.

8) Fire Hole

The fire hole uses to introduce fuel into the locomotive boiler. This hole is also located over the grate. The coal fuel introduces through this hole.

9) Firebox

It is a place where solid fuel is combusted. The bars of the grate is installed at the firebox bottom.

10) Smoke Box Door

This door uses to clean the boiler.

11) Smokebox

The smokebox uses to collect the smoke of the combusted coal. The smoke enters into this smokebox after passing through the fire tube.

12) Blast Pipe

The blast pipe installs on the steam engine. The useless steam flows via this pipe. This pipe uses to make an artificial draft, which uses to remove smoke from the chimney and create suction for the flue gas.  The resulting suction allows the hot gas to flow forward via the fire tube.

13) Super Heater Header

This component of the locomotive boiler uses to accumulate saturated steams and convert them into a superheated state. The produced superheated steam is introduced into the fire tube via a superheater tube installed in the fire tube. This superheater tube has a smaller diameter compared to the fire tube.

14) Chimney

It has a small size, and the gas in the boiler is removed by an artificial blower. The chimney uses to eliminate the useless gases, smoke, and exhaust from the boilers.

15) Steam Dome

As the boiler generates steam, the steam dome uses to gather this steam. The dome has a steam regulator that is installed inside the dome.

16) Super Heater Tubes

These tubes are installed in the fire tube. The superheater tube has a small size than the fire tube. As the superheater produces superheated steam, the steam enters into the fire tubes through superheater tubes.

17) Safety Valve

The safety valve ensures safe working steam pressure. It removes the excess steam pressure from the locomotive boiler. As the steam pressure becomes more than a specific level or boiler’s bearing capacity, the safety valve opens, steam is emitted, and the boiler is prevented from explosion.

Read Also: Different Types of Valves

18) Steam Regulator

The steam regulator uses to regulate the flow of steam. It uses to add steam when the worker pulls the lever. This unit controls the steam of the superheater through the main steam line.

19) Blow Off Cock

This part of the boiler uses to eliminate slurries and other contaminations from the boiler. The blow-off Cock also uses to eliminate the wastewater from the boiler.

20) Exhaust steam Pipe

The exhaust steam pipe uses to remove the exhaust steam from the steam engine.

21) Manhole

A manhole is a hole through which the worker can go inside the boiler. In maximum cases, the employees use this hole to clean, maintain or change the parts of the boiler. It is wide enough that a worker can easily enter into the boiler.

22) Pressure Gauge

The pressure gauge represents the boiler’s inner steam pressure. It has different indication marks through which you can easily understand the pressure level inside the boiler.

23) Water Level Indicator

The water level indicator device is located in the water tank of the boiler. It represents the water level in the boiler tank.

Advantages and Disadvantages of Locomotive Boiler

The locomotive boiler has the following advantages and disadvantages:

Advantages of Locomotive Boiler

  • The steam generation of the locomotive boiler is very high.
  • This type of boiler has an easy operation.
  • They have a low cost.
  • These boilers have a compact size and can be easily shifted from one place to another.
  • This boiler has the capability to fulfill the fluctuating and sudden demands of steam.

 Disadvantages of Locomotive Boiler

  • The cleaning of some areas is very hard.
  • You can’t use this boiler under heavy load situations because it overheats under heavy load.
  • There are also many chances of corrosion formation.

Applications of Locomotive Boiler

  • The locomotive boilers are employed in the steam roller.
  • These boilers are depleted in many vehicles and small steam engines.
  • These types of boilers are used in ships.
  • The locomotive boiler uses in railway engines.
  • It is employed in a traction engine.
  • Different heritage railways all over the world use steam locomotives as a way to preserve and showcase the history of rail transportation.

FAQ Section

What type of boiler is a locomotive boiler?

A locomotive boiler is a natural circulation, multi-tubular, fire-tube boiler. 

What is a locomotive boiler?

A locomotive boiler is a boiler that produces steam from water by utilizing the heat of the flue gases. It is a medium pressure, forced circulation, artificial draft, horizontal drum axis, and fire tube boiler.

What are the applications of locomotive boilers?

The locomotive boiler is used in applications such as traction engines, railway engines, ships, and steam rollers.

What is the function of the Locomotive Boiler?

This boiler has a large area of the grate. Therefore, the main function of the locomotive boiler is to produce steam at a high rate.

Why is there no chimney in a locomotive boiler?

This type of boiler uses a stack. This is because the locomotive boiler is portable, and it can easily shift from one area to another. Therefore, installing a chimney is unnecessary, and the generated airflow over the stack eliminated the hot flue gases created due to the difference in pressure between the outside and the grate.

Who Invented the Locomotive Boiler?

In 1802, Richard Trevithick designed the first locomotive boiler. 

What are the parts of the locomotive boiler?

  1. Superheater
  2. Boiler shell
  3. Fire brick arch
  4. Grate
  5. Ashpit
  6. Fire tubes
  7. Fire hole
  8. Deflector
  9. Blast pipe
  10. Smoke box
  11. Smoke box door
  12. Firebox
  13. Chimny 
  14. Superheater head
  15. Steam dome
  16. Superheater tubes
  17. Safety valves
  18. Steam regulator 
  19. Blow off cock 
  20. Exhaust steam pipe
  21. Manhole
  22. Pressure guage 
  23. Water level indicator

What is the efficiency of locomotive boiler?

Locomotive boilers typically have an efficiency of about 70%. But this efficiency can be further improved by connecting a superheater. The inclusion of a superheater in the locomotive boiler improves its efficiency.

Read More
  1. Different types of Boilers
  2. Working of Lancashire Boiler
  3. Working of Lamont Boiler 
  4. Different types of Valves

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