Fire Tube Boiler |What It's Operation?? and Types of Fire Tube Boiler

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Fire tube boiler is one of the most basic type of boiler and the design is also very old. We can identify it's oldness by this, that  It was used for steam locomotive engines. And at that time it was so popular.

Operation of Fire Tube Boiler:-

Operation of fire tube boiler is very simple like its construction.

In fire tube boiler, the fuel is burnt inside the furnace area. By this hot gases produced in the furnace area then this hot air is passes through the fire tubes. And These fire tubes are submersed into water inside the  vessel of the boiler.

As the hot gases are passed through these multi tubes, the heat energy of the hot gasses is transferred to the water surrounds hot gasses pipe tubes.
As a result the water is heated and converts into the steam.
Thus the steam is generated in the water and naturally comes up and stored upon the water in the same vessel of boiler.

Now this steam is then taken out from the boiler via steam outlet for utilities for required aap application.
and the water is fed into the boiler through the feed water system.

As the steam is stored above water in  the same vessel, then it becomes quite difficult to produce very high pressure steam from.

Maximum capacity of this type of boiler is 17.5 kg/cm² and with a capacity of 9 Metric Ton of steam per hour.

Types of Fire Tube Boiler

Classification of boiler

According to the installation of furnace there are two types of fire tube boiler external furnace type.
internal furnace type.

These are mainly three types of external furnace fire tube boiler.

Horizontal return tubular fire tube boiler.

Short fire box fire tube boiler.

Compact fire tube boiler.

There are also two types of internal furnace fire tube boiler

Horizontal tubular.

Vertical tubular fire tube boiler.

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Working Principle of Horizontal Fire Tube Boiler.

How a boiler works diagram

Horizontal  fire tube boiler is mostly used for low capacity thermal power plant.
Main construction part of this boiler system is a big hollow cylindrical shape drum which is place horizontally with the help of supporting structure.
          And there are many tubes inside this hollow cylindrical drum which are comes from furnace.
And these tubes are also aligned horizontally in the drum.
And these tubes are submersed into the drum.

The fuels burnt inside the furnace and produced gasses move into the fire tubes, through these tubes from the furnace to the boiler drum and finally the gases come into the smoke box.

The hot gasses which are inside the tubes under water, transfer heat to the water via the tube walls. Due to this heat energy is transferred by convection method. And this steam generates bubbles  and these come upon the water surface.

As the amount of steam is increased in that closed vessel, steam pressure inside the drum slightly increasesy which increase significantly the boiling temperature of the water and hence rate of production of steam is reduced.
To prevent this reduce of steam production we take out this generated steam through the exit pipe at desired places.

  this is a self pressure controlled boiler.

Advantages of Fire Tube Boiler

Easy in construction.

Fluctuation in demand steam.

Cheaper than water tube boiler.

Disadvantages of Fire Tube Boiler
Pressure inside the drum is slightly high.

More water is needed in this type of boiler.

Output steam pressure not be very high since the water and steam are placed in same vessel.

The steam from fire tube boiler is not dry.

Click here to read classification of boilerhttps://www.mechanicadda.tech/2020/07/Whatis-boiler-and-its-classification.html

In a fire tube boiler, the steam drum is always under pressure, so there may be a chance of explosion which leads  to accident.

Application of the boiler

Fire Tube Boilers are commonly used in
1.railways,
2.marines,
3.and industrial sectors.

Next
Water tube boiler