Internally Fired Boiler - Lancashire Boiler

Introduction:
An internally fired boiler is a type of boiler where the furnace or firebox is located inside the boiler shell. In this type of boiler, the combustion of fuel occurs internally and the heat is transferred to the surrounding water through the walls of the boiler.

Lancashire Boiler:
The Lancashire boiler is a type of internally fired boiler. It is a horizontal, fire-tube boiler that consists of two large flue tubes surrounded by water and placed horizontally across the boiler shell. The flue tubes are joined at the front and rear ends by two curved plates known as furnace flue plates or end plates. The furnace or firebox is located between these two flue tubes.

Working Principle:
The fuel, such as coal or wood, is fed into the furnace from the front end of the boiler. The combustion of fuel takes place inside the furnace, where it is ignited by the burner. The hot gases produced by the combustion pass through the flue tubes, heating the water surrounding them. The flue gases then exit the boiler through the chimney.

Advantages:
1. The design of the Lancashire boiler allows for a large heating surface area, which results in efficient heat transfer and high steam production.
2. It has a robust construction and can withstand high pressure and temperature.
3. The boiler can be easily cleaned and maintained due to its simple design.
4. It has a relatively high thermal efficiency.

Disadvantages:
1. The size and weight of the Lancashire boiler are relatively large compared to other types of boilers.
2. It requires a large amount of water to fill the boiler, which can lead to high initial costs and increased operating expenses.

Conclusion:
In conclusion, the Lancashire boiler is an example of an internally fired boiler. It is a reliable and efficient type of boiler that has been widely used in various industries for steam generation. Its simple design and robust construction make it suitable for applications where a large amount of steam is required.