Boiler Basics: 17 MCQs with answers

Fire tube boiler

A Lancashire boiler is a fire tube boiler because hot gases pass through the tubes surrounded by water.

Two

A Lancashire boiler has two large flue tubes running longitudinally through the shell.

Coal

Lancashire boilers are traditionally coal-fired, with grates at the front of each flue tube.

To support the fuel bed and allow air to pass through

The grate supports the solid fuel and permits primary air to flow upward through the fuel bed for combustion.

To allow inspection and cleaning of the interior

The manhole is an access opening that permits personnel to enter the boiler for inspection, cleaning, and maintenance.

Safety valve

Safety valves are essential mountings that automatically release steam to prevent overpressure. Superheaters, economizers, and air preheaters are accessories, not mountings.

Fire tube

In a fire tube boiler, hot gases flow through tubes that are surrounded by water, which is the fundamental principle of the Lancashire boiler.

False

The Lancashire boiler is a fire tube boiler, not a water tube boiler.

To deflect the hot gases upward and prevent direct impingement on the tubes

The fire bridge is a brick wall that deflects hot gases upward, preventing them from directly striking the tube ends and improving heat transfer.

Low steam generation rate

Lancashire boilers have a low steam generation rate due to their large water volume and limited heating surface area.

Up to 16 bar

Lancashire boilers are low-pressure boilers, typically operating up to about 16 bar.

To ensure safe operation and control

Mountings are essential fittings like safety valves, pressure gauges, and water level indicators that ensure safe and controlled operation.

Locomotive traction

Lancashire boilers are stationary and too bulky for locomotives; they are used in stationary applications like process heating and small power generation.

Better ability to handle fluctuating steam demand

The large water volume acts as a thermal reservoir, allowing the boiler to respond to sudden changes in steam demand without significant pressure drops.

Low efficiency and large floor space requirement

Lancashire boilers have relatively low efficiency and occupy a large floor area, making them less economical for modern high-demand applications.

Bottom flue

After passing through the main flue tubes, the gases are directed downward through the bottom flue (or side flues) to increase heat transfer before reaching the chimney.

False

Lancashire boilers are low-pressure boilers, typically operating up to about 16 bar, and are not suitable for high-pressure applications.