Lancashire boiler is a Stationary fire tube boiler

Introduction
The Lancashire boiler is a type of stationary fire tube boiler that is widely used in industrial applications. It was developed in the early 19th century in Lancashire, England, hence the name. The Lancashire boiler is known for its efficiency, reliability, and ease of operation.

Construction
The Lancashire boiler consists of a horizontal cylindrical shell with two large flue tubes running through it. The flue tubes are surrounded by water and extend beyond the front and rear ends of the boiler. The shell is made of steel plates and is strong enough to withstand high pressure.

Fire Tubes
The fire tubes are located inside the boiler shell and carry hot gases from the furnace to the chimney. These tubes are surrounded by water, which absorbs heat from the gases, resulting in the generation of steam. The hot gases pass through the tubes multiple times, increasing the heat transfer efficiency.

Furnace
The furnace is located at the front end of the boiler and is where the combustion of fuel takes place. It is lined with refractory material to withstand high temperatures. The fuel, such as coal or oil, is burned in the furnace, producing hot gases that flow through the fire tubes.

Water Space
The space surrounding the fire tubes is filled with water, which acts as a heat transfer medium. The water absorbs heat from the hot gases and gets converted into steam. The steam is collected in the space above the water level, known as the steam space.

Features
- Stationary: The Lancashire boiler is a stationary boiler, meaning it is not portable and is installed in a fixed location.
- Fire tube: It is a fire tube boiler, as the hot gases pass through the tubes and the water surrounds them.
- Efficiency: The Lancashire boiler is known for its high efficiency due to the multiple passes of hot gases through the tubes.
- Reliability: It is a reliable boiler with a simple design and sturdy construction.
- Ease of operation: The Lancashire boiler is easy to operate and requires minimal maintenance.

Therefore, the correct answer is option 'A' - Stationary fire tube boiler.