Boiler and Steam Systems Flashcards
7 cards from real CEM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Boiler and Steam Systems flashcards as text
What is 'cogeneration' (CHP) in the context of a steam boiler system?
Answer: Simultaneous generation of electricity and useful thermal energy from a single fuel source
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.
Scale deposits on the waterside of boiler tubes primarily cause:
Answer: Reduced heat transfer leading to overheating, tube failure, and increased fuel consumption
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.
Which steam system audit measurement best indicates steam trap failure rates across a plant?
Answer: Systematic ultrasonic or infrared temperature survey of all steam traps in service
Ultrasonic and infrared surveys detect both failed-open (blow-through) and failed-closed (waterlogged) traps non-invasively during normal operation.
The economizer in a firetube boiler is positioned where in the flue gas path?
Answer: After the boiler tubes in the exhaust stream to recover heat into feedwater
Economizers are placed downstream of the boiler tubes to extract remaining heat from flue gas and transfer it to incoming feedwater, raising overall efficiency.
A facility operates a 150 psig steam system but most process loads only need 15 psig. The most energy-efficient upgrade would be:
Answer: Reduce boiler operating pressure to 15 psig after confirming all equipment compatibility
Operating the entire system at lower pressure reduces radiation losses, condensate losses, and feedwater pump work, and may eliminate the need for PRVs.
In ASME Boiler and Pressure Vessel Code context, what does 'MAWP' stand for and why does it matter for CEM?
Answer: Maximum Allowable Working Pressure — the safe operating limit that cannot be exceeded without risking vessel failure
MAWP is the maximum pressure at which a boiler is certified to operate safely; exceeding it risks catastrophic failure and violates code compliance.
Which operating practice reduces standby losses for a boiler kept on hot standby?
Answer: Lowering steam pressure setpoint to the minimum needed to restart quickly and insulating the boiler shell
Reducing standby pressure and improving insulation minimizes radiation and convection losses from the boiler shell during periods of no steam demand.