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
A flash steam recovery system on a high-pressure condensate line generates flash steam for use at lower pressure. What thermodynamic principle governs this?
Answer: Throttling of saturated liquid causes partial vaporization as pressure drops, releasing flash steam
When high-pressure condensate is throttled to lower pressure, some liquid flashes to steam because enthalpy is conserved and saturation temperature drops.
Which blowdown strategy is most energy-efficient for controlling boiler water Total Dissolved Solids (TDS)?
Answer: Continuous blowdown with heat recovery using a blowdown heat exchanger
Continuous blowdown with a heat exchanger recovers thermal energy from the blowdown stream, minimizing both water and heat losses.
What does the term 'boiler horsepower' (BHP) represent?
Answer: The evaporation of 34.5 lb/hr of water at 212°F, equivalent to approximately 33,475 BTU/hr
One boiler horsepower equals the evaporation of 34.5 lb/hr of feedwater at 212°F, a traditional unit equal to about 33,475 BTU/hr.
In a steam system, what is the primary function of a pressure-reducing valve (PRV)?
Answer: To step down steam pressure to match lower-pressure distribution or end-use requirements
A PRV reduces high-pressure steam to a lower set-point pressure suitable for specific process or building heating loads.
Which factor most directly determines the 'M' factor (fuel-to-steam efficiency) used in boiler performance assessment?
Answer: Ratio of useful heat absorbed by steam to the heat input from fuel combustion
Fuel-to-steam efficiency measures how much of the fuel's heat content is transferred into the steam, accounting for stack losses, radiation, and blowdown.
Foaming in a boiler steam drum is most likely caused by:
Answer: High concentrations of dissolved solids or surfactants in the boiler water
High TDS or oil contamination causes surface tension reduction in boiler water, leading to foam and carryover of water droplets into the steam.
What is the recommended approach when a facility wants to lower steam system operating pressure to save energy?
Answer: Audit all end-use equipment to verify they can operate at lower pressure before reducing system pressure
Lowering steam pressure reduces losses but requires confirming all process equipment, controls, and steam traps will function correctly at the new pressure.