FREE CEM Test Boiler and Steam Systems Questions and Answers

Question 1

An energy manager reviewing boiler operations notices a gradual increase in stack gas temperature over several months, even though the firing rate and excess air levels have remained consistent.
What is the most likely cause of this change?

Accepted Answer

Fouling of heat transfer surfaces inside the boiler.

Answer

A decrease in feedwater temperature.

Answer

A malfunctioning steam trap in the distribution system.

Answer

An increase in ambient air humidity.

Question 2

What is the primary purpose of continuous (or surface) blowdown in a boiler system?

Accepted Answer

To control the concentration of Total Dissolved Solids (TDS) in the boiler water.

Answer

To remove sludge and sediment from the bottom of the boiler drum.

Answer

To test the operation of the low-water cutoff safety device.

Answer

To rapidly lower boiler pressure during an emergency shutdown.

Question 3

An auditor is inspecting a steam distribution system and suspects a particular steam trap has failed in the open position. Which of the following observations would most strongly confirm this suspicion?

Accepted Answer

A large, continuous plume of live steam is visibly venting from a nearby condensate receiver tank.

Answer

The pipe immediately downstream of the trap is cool to the touch.

Answer

Water hammer and banging noises are heard in the condensate return line.

Answer

The process equipment being served by the trap is not reaching its target temperature.

Question 4

A boiler's flue gas economizer improves overall system efficiency by performing which of the following functions?

Accepted Answer

Transferring waste heat from the flue gas to the incoming boiler feedwater.

Answer

Recirculating a portion of the flue gas back into the burner to reduce NOx emissions.

Answer

Using hot flue gas to preheat the combustion air before it enters the burner.

Answer

Using a catalyst to promote more complete combustion of fuel.

Question 5

Which of the following is a significant negative consequence of having too much excess air in the boiler combustion process?

Accepted Answer

Decreased boiler efficiency due to excess heat being carried up the stack.

Answer

Increased production of carbon monoxide (CO) and soot.

Answer

A higher risk of furnace explosion due to unburnt fuel.

Answer

Corrosion of boiler tubes due to flue gas condensation.

Question 6

A facility insulates 200 feet of previously bare 4-inch steam pipe. What is the primary energy-saving mechanism of this action?

Accepted Answer

It reduces radiant and convective heat loss from the pipe surface.

Answer

It increases the temperature of the steam inside the pipe.

Answer

It reduces the pressure drop along the length of the pipe.

Answer

It increases the velocity of the steam flowing through the pipe.

An energy manager reviewing boiler operations notices a gradual increase in stack gas temperature over several months, even though the firing rate and excess air levels have remained consistent.What is the most likely cause of this change?

An energy manager reviewing boiler operations notices a gradual increase in stack gas temperature over several months, even though the firing rate and excess air levels have remained consistent.
What is the most likely cause of this change?