Diesel Fire Tube Boiler

Fire tube boiler is one of the most basic types of boiler and the design is also very old. It was popular in 18th century. A fire-tube boiler is a type of boiler in which hot gases pass from a fire through one or (many) more tubes running through a sealed container of water. The heat of the gases is transferred through the walls of the tubes by thermal conduction, heating the water and ultimately creating steam.

For this type boiler heat passes through the boiler drum or tube. For this reason, the Heating Surface of the Fire Tube Boiler is less than 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) steam per hour.

From a maintenance standpoint, firetube boilers are typically have lower operating costs comparable to a similarly sized watertube boiler. Firetube boilers have easy access to the boiler’s firesides and tubes can easily be replaced without additional repair of the boiler. Although firetube boilers are smaller in design, they have a larger water volume than similar size watertube boilers, causing them to take longer to bring up to operating temperature from a cold start.  Once a firetube boiler is started up and is operating at its desired pressure, a firetube boiler can handle a sudden upward load surge better than a watertube boiler because of the large steam disengaging area. The drawback to this feature is once the pressure of a firetube is dropped, it takes longer to catch back up. With less water volume, a watertube boiler has the ability to follow load swings more precisely and generally has better turndown than a firetube boiler.

Advantages of Fire Tube Boiler
1. Compact in construction.
2. Fluctuation of steam demand can be met easily.
3. Cheaper than water tube boiler.

Disadvantages of Fire Tube Boiler
1. Due to large water the required steam pressure rising time quite high.
2. Output steam pressure cannot be very high since the water and steam are kept in same vessel.
3. The steam received from fire tube boiler is not very dry.
4. 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.