Locomotive boiler is horizontal drum axis, artificial draft, natural circulation, multi-tubular, mobile, forced circulation, medium pressure, solid fuel fired fire tube boiler with the internally fired furnace.
It is used in marine engines and railway locomotive engines. It is a mobile boiler and has a high steam generation rate.
Parts of Locomotive Boiler
The main construction parts of a locomotive boiler are as follows:
- Fire hole
- Fire brick arch
- Boiler tubes
- Blast pipe
- Superheater element pipe
- Superheater header
1. Fire hole
It is hole provided at the air rear end of the boiler. The solid fuel is entered and burned into the furnace through this hole.
The firebox is a type of a box in this the burning of the fuel takes place.
The grate is a platform on which the solid fuel is kept and burnt.
4. Fire brick arch
Fire brick arch is placed inclined over the grate. It prevents dust, ash and burnt fuel particles from entering into the fire tubes. This arch provides a way to the hot exhaust gases to travel a definite path before entering the fire tubes of the boiler.
5. Boiler tubes
They are the fire tubes through which the hot exhaust gases pass and exchange the heat with the surrounding water.
According to its name, it is a box in which the smoke of the burnt fuel after passing through the fire tubes gets collected. From there it exhausted in the environment by the chimney.
7. Blast pipe
It is pipe provided above the steam engine. The exhaust steam passes through this blast pipe. It is used to create the artificial draft that pushes the smoke out through the chimney and creates suction for the hot exhaust gases. The suction created allows the hot exhaust gases to move forward through the fire tubes.
It is the pipe through which the steam passes. We have two steam pipes, one in the main steam pipe present in between the superheater header and dome. And the second one is that which connects the superheater exit end to the steam engine.
It is present at the top and contains the regulator for regulating the steam produced through the steam pipe.
10. Superheater element pipes
These are the pipes of superheater through which the steam travels and gets superheated.
11. Superheater header
It is the head of the superheater which accepts the steam from the steam pipe.
It is used to throw out the exhaust smoke and gases to the environment. The length of the chimney is very small in this boiler.
Boiler Mountings and Accessories of Locomotive Boiler
Locomotive boiler mountings and accessories are as follows:
- Water level indicator
- Pressure gauge
- Blow off valve
- Regulator Valve
- Safety Valve
1. Water Level Indicator
It is a device employed to show the water level in a boiler.
2. Pressure Gauge
It is a device that determines the boiler pressure reading.
3. Blow-off valve
The purpose of the blow-off valve is to remove the mud and other sediments. It can also be applied for drain-off boiler water.
It superheats the steam to the desired temperature before entering into the cylinder of the steam engine.
5. Regulator Valve
It is a valve that regulates the steam through the main steam pipe for superheating.
6. Safety Valve
It is used to maintain the safe working steam pressure in the locomotive boiler. It blows off steam when the pressure of the steam increases above safety level and prevents blasting oof the boiler.
Working of Locomotive Boiler
In a locomotive boiler, first, the solid fuel (coal) is inserted on the grate and is ignited from the fire hole. The burning of the fuel starts and it creates hot exhaust gases. A fire brick arch is provided that makes the flow of hot exhaust gases to a definite path before entering into the long tubes (fire tubes). It also prevents the entry of burnt of solid fuel particles into the fire tubes.
The hot exhaust gases pass through the long fire tubes and heat the water surrounding them. Due to the heating, water gets transformed into saturated steam and collected at the top. Saturated steam from a dome enters into the steam pipe with the help of a regulator valve. The steam travels in the main steam pipe and reaches to the superheater header. From header, the steam enters into the superheater element pipes.
Here it is superheated and then the superheated steam enters into the steam pipe of the smokebox. The steam from the superheater goes to the cylinder containing the piston. The superheated steam made the piston moves within the cylinder. The piston is connected to the wheels of the steam engine and the wheels start rotating. The exhaust steam from the cylinder enters into the blast pipe.
The burnt gases and smoke after passing through the fire tubes enter into the smokebox. The exhaust steam coming out from the blast pipe pushes the smoke out of the boiler through the chimney. Here the smoke cannot escape out from the boiler by its own, so artificial draft is created by exhaust steam coming out from the steam engine. This artificial draft created pushes the smoke out of the smokebox and creates suction for the hot exhaust gases.
Advantages of Locomotive Boiler
- It is portable.
- This boiler is capable of meeting sudden and fluctuating demands of steam.
- It is a cost-effective boiler.
- High steam generation rate.
- It is compact in size and its operation is easy.
Disadvantages of Locomotive Boiler
- It faces the problems of corrosion and scale formation.
- Unable to work under heavy load conditions because of overheating problems.
- Some of its water space are difficult to clean.
- The overall efficiency is less.
Application of Locomotive Boiler
- Locomotive boilers are used in railways and marines.
- This type of boiler is used in traction engines.
- This is also used in steam rollers.
- It is can be used in portable steam engines and some other steam road vehicles.
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