CEM Boiler and Steam Systems 4

Question 1

What is 'cogeneration' (CHP) in the context of a steam boiler system?

Accepted Answer

Simultaneous generation of electricity and useful thermal energy from a single fuel source

Answer

CHP (Combined Heat and Power) generates both electricity and useful heat from one fuel input, achieving overall efficiencies of 70–85% versus ~33% for power-only plants.

Question 2

Scale deposits on the waterside of boiler tubes primarily cause:

Accepted Answer

Reduced heat transfer leading to overheating, tube failure, and increased fuel consumption

Answer

Scale has very low thermal conductivity (~0.5 BTU/hr·ft·°F vs ~25 for steel), so even thin deposits significantly impede heat transfer and raise tube metal temperatures.

Question 3

Which steam system audit measurement best indicates steam trap failure rates across a plant?

Accepted Answer

Systematic ultrasonic or infrared temperature survey of all steam traps in service

Answer

Ultrasonic and infrared surveys detect both failed-open (blow-through) and failed-closed (waterlogged) traps non-invasively during normal operation.

Question 4

The economizer in a firetube boiler is positioned where in the flue gas path?

Accepted Answer

After the boiler tubes in the exhaust stream to recover heat into feedwater

Answer

Economizers are placed downstream of the boiler tubes to extract remaining heat from flue gas and transfer it to incoming feedwater, raising overall efficiency.

Question 5

A facility operates a 150 psig steam system but most process loads only need 15 psig. The most energy-efficient upgrade would be:

Accepted Answer

Reduce boiler operating pressure to 15 psig after confirming all equipment compatibility

Answer

Operating the entire system at lower pressure reduces radiation losses, condensate losses, and feedwater pump work, and may eliminate the need for PRVs.

(CEM) Certified Emergency Manager Practice Test

(CEM) Certified Emergency Manager Practice Test

CEM Boiler and Steam Systems 4