Boiler Basics: 18 MCQs with answers

To convert water into steam using heat energy

A boiler's main purpose is to generate steam by transferring heat from combustion to water.

To release excess pressure to prevent explosions

Safety valves automatically release steam when the pressure exceeds a safe limit, protecting the boiler from overpressure.

Water level indicator

A water level indicator (or water gauge) shows the water level in the boiler drum, ensuring safe operation.

Pressure gauge

Boiler mountings are essential fittings for safe operation, such as pressure gauges, safety valves, and water level indicators.

To supply water to the boiler at the required pressure

A feedwater pump delivers water to the boiler at a pressure higher than the boiler's operating pressure to ensure continuous water supply.

False

Safety valves are mandatory boiler mountings; they prevent overpressure and explosions.

True

Economizers recover waste heat from exhaust gases to raise feedwater temperature, improving efficiency.

Lancashire boiler

Lancashire boiler is a classic example of a fire-tube boiler where hot gases pass through tubes submerged in water.

Higher steam generation capacity and pressure

Water-tube boilers can operate at higher pressures and produce more steam because water is contained in smaller tubes, allowing faster heat transfer and better circulation.

To collect impurities and sludge

The mud drum is located at the bottom of a water-tube boiler and collects sediment, sludge, and other impurities that settle out of the water.

Deaerator

A deaerator removes oxygen and other dissolved gases from feedwater to prevent corrosion in the boiler system.

To preheat feedwater using exhaust gases

An economizer recovers heat from flue gases to preheat the feedwater, improving overall boiler efficiency.

To increase the temperature of steam above its saturation point

A superheater adds heat to saturated steam, raising its temperature and reducing moisture content, which improves turbine efficiency.

To remove condensate and non-condensable gases from steam lines

Steam traps automatically discharge condensate and air from steam systems while preventing steam loss.

The process of removing concentrated impurities from the boiler water

Blowdown is the controlled removal of water from the boiler to reduce the concentration of dissolved solids and sludge.

To heat combustion air using flue gas heat

An air preheater recovers heat from flue gases to preheat the air used for combustion, improving fuel efficiency.

Fuel valve

A fuel valve regulates the amount of fuel supplied to the burner, controlling the heat input to the boiler.

Lower maximum pressure and steam generation rate

Fire-tube boilers are limited to lower pressures and steam capacities due to the large water volume and thick shells.