Boiler Basics: 19 MCQs with answers

Hot gases

In a fire-tube boiler, hot combustion gases pass through the tubes, which are surrounded by water.

Water and steam

In a water-tube boiler, water and steam circulate inside the tubes, while hot gases pass around them.

To produce steam by heating water

A boiler's main purpose is to convert water into steam by applying heat, typically from combustion.

Hot combustion gases

In water-tube boilers, hot gases flow around the tubes to transfer heat to the water inside.

Small industrial plants and heating systems

Fire-tube boilers are widely used in small to medium-sized industries and for heating due to their simplicity and lower cost.

False

This is the opposite: in a fire-tube boiler, hot gases flow through the tubes, and water surrounds them.

Water-tube boiler

Water-tube boilers can handle higher pressures and capacities because the water is contained in smaller-diameter tubes, which can withstand higher pressures.

Can be horizontal or vertical

Fire-tube boilers can have horizontal or vertical tube arrangements, depending on the design.

Water-tube boiler

Water-tube boilers have a smaller water volume and higher heat transfer rates, allowing them to respond more quickly to changes in steam demand.

Lower initial cost and simpler construction

Fire-tube boilers are generally simpler in design and less expensive to manufacture and install, making them cost-effective for moderate pressure and capacity needs.

Water-tube boiler

Large power plants require high pressure and high capacity, which water-tube boilers can provide efficiently.

Convection and radiation

Boilers transfer heat primarily through convection (hot gases moving over surfaces) and radiation from the flame and hot gases.

Water-tube boiler

Water-tube boilers have more complex construction with many tubes and drums, requiring specialized knowledge for maintenance and repair.

Fire-tube boiler

Fire-tube boilers have a large shell filled with water, resulting in a high water volume compared to the steam produced.

To separate steam from water

The steam drum collects the steam generated in the tubes and helps separate it from the water before it leaves the boiler.

Fire-tube boiler

Fire-tube boilers are often more compact for lower capacities because they have a simple shell-and-tube design, while water-tube boilers require more space for drums and tubes.

True

Water-tube boilers use smaller-diameter tubes that can withstand higher pressures, making them suitable for high-pressure applications.

Fire-tube boiler

Fire-tube boilers contain a large volume of water under pressure; if a tube fails, rapid steam release can cause a violent explosion.

Up to 30 bar

Fire-tube boilers are generally limited to pressures around 30 bar due to the large shell diameter, whereas water-tube boilers can go much higher.