Operation of Fire Tube Boiler
The operation of fire tube boiler is have a simple its construction, in the fire tube boiler, the fuel is burnt inside a furnace. The heat energy produced in the furnace then flow passes through the fire tubes construction. The fire tubes in immersed in water inside the main vessel of the boiler. As the heat energy gases are flow passed through these tubes, the heat energy of the gasses is transferred to the water surrounds them. This result is the steam generated in the water and naturally and continue comes up and is stored upon the water in the same vessel of fire tube boiler.
Looat the location of furnace there are two types of fire tube boiler, there are external furnace and internal furnace type.
There are two types of internal furnace fire tube boilers:
1. Horizontal tubular.
2. Vertical tubular fire tube boiler.
The mainly hree types of external furnace fire tube boiler.
1. Compact fire tube boiler.
2. Horizontal return tubular fire tube boiler.
3. Short fire box fire tube boiler.
Thermal power plant with low capacity is suitable to use the horizontal return fire tube boiler. The features of constructional for type of this boiler is one big size steam drum which lines horizontally upon supporting structures. The numbers of fire tubes come from furnace and also aligned to horizontally inside the drum. When drum is filled with water these are submerged in the water.
In the furnance, the fuels burnt and combustible gasses move into the fire tubes. The flow through these tubes from rear to front of the boiler drum and finally the gases come into the smoke box. The tube starts to be heated from the bottom using the heat flowing through the tubes walls, this heat energy steam bubbles are created and come upon the water surface. Big amount of steam is increased and presure in that closed drum, steam pressure inside through the drum increases compared straight the boiling temperature of the water and rate of production of steam is reduced. In this way a fire tube boiler controls its own pressure, in other words this is a self pressure controlled boiler.
Advantages types of this boilers:
1. Sturdy construction.
2. Fluctuation of steam demand can be met easily (for Low uses).
3. Cheaper than water tube boiler.
Disadvantages type of this boilers:
1. Due to large water the required more time to increses the presure.
2. Output steam pressure cannot high since the water and steam are kept in same vessel (basicly because for low user pressure)
3. The steam received from fire tube boiler is not very dry.
In a fire tube boiler, the steam drum is always under pressure, so there may be a chance of huge explosion which resulting to severe accident.