What is a Fire Tube Boiler?

In one sentence we can say that, a Fire Tube Boiler is a type of Boiler in which hot gases pass through the boiler fire tube and water passes through around the fire tube.

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We all know that industrial boilers always come with Tubes and most of them are in different shapes and sizes. By this tube, a boiler can be separated into two types. The first one is a Water Tube Boiler and the Second one is a Fire Tube Boiler. It’s also very basic differences between boilers. In this article, we will learn about the Fire Tube Boiler with its working principle and its Type.

What is a Fire Tube Boiler?

In one sentence we can say that, a Fire Tube Boiler is a type of Boiler in which hot gases pass through the boiler fire tube and water passes through around the fire tube. Generally, a Fire Tube Boiler can be Horizontal, Vertical, Inclined Position, and External or Internally Fired. In the past, all over the world Fire Tube Boiler was used on virtually all steam locomotives in the horizontal "locomotive" form. Now it will be hard to find this type of steam locomotive.

For this type of boiler heat passes through the boiler drum or tube. For this reason, the Heating Surface of the Fire Tube Boiler is less than a general Water Tube Boiler. Fire Tube Boiler generates less steam than Water Tube Boiler. Some experiments found that a Fire Tube Boiler can generate 18000 pounds (8164 Kg) of steam per hour.

When the Fire Tube Boiler was invented that time it was a popular boiler for different sectors. At that time Wood, Saw Dust, and Cola were used to burn to supply heat to the boiler. Nowadays you can find boilers in the textile industry that are fired by garments wasted fabric. But we generally use Pulverised Cola, Natural GAS, and Crude Oil as fuel for the Fire Tube Boiler. But nowadays this type of boiler is not as popular as before.

Working Principle of Fire Tube Boiler:

Let’s learn about the working principle of a locomotive-type boiler as an example of a Fire Tube Boiler. In this type of boiler, fuel is used to burn inside the Combustion Chamber or Fire Box. Hot combustion gases are produced from this section. The firebox use to surrounded by a cooling jacket of water which is connected to the long, cylindrical boiler shell. When combustion hot gases pass through the series of fire tubes, or flues and heat the surrounding water. This is a very general process of transferring heat from one place to another place.

In this way, we can get our first level of steam. This generated steam is called wet or saturated steam. Then this saturated steam rises to the top point of this Fire Tube Boiler and is called a Steam Dome. It is a place where saturated steam is collected. This Dome is used to regulate the exit of steam amount from the boiler.

From the Dome, steam is transferred to another furnace where it becomes super-heated steam. Because in locomotive-type boilers saturated steam is not the working steam. When steam is superheated then it transfers to the engine cylinder to generate mechanical energy.

Types of Fire Tube Boiler:

There are a few types of Fire Tube Boiler available and those are –