6 Questions
What is the consequence of inadequate atomizing medium pressure for air or steam-atomized burners?
Low quality flames
Why should the low atomizing medium cut-off switch extinguish the burner before flame failure occurs?
To avoid poor quality oil flames
How often do UV scanners typically need replacement?
Every 40,000 hours
What is a potential consequence of flame rods coming out of alignment over time?
Failure to detect the pilot or main flame
Why is it important to ensure flame scanners have adequate cooling air while in service?
To prevent exposure to high temperatures
What should be done if a boiler fails to light off or has repeated flame failures despite meeting all normal operating parameters?
Contact a certified technician for inspection
Study Notes
Power Failure and Response
- Power failure requires immediate and effective operator response
- Operators must be well-versed in plant blackout procedures and follow them closely
- Considerations for responding to power failure include:
- Control valve failure positions (open, shut, or last)
- Equipment fed by standby power and uninterruptable power
- Manual startup of standby generator and automatic transfer switch
- Plant load shedding strategies
- Restarting equipment after power restoration
- Sequence of starting equipment after power restoration
Equipment Response to Power Failure
- Electrically powered equipment stops, unless connected to an uninterruptable power source (UPS)
- Some equipment restarts automatically when normal power is restored, including:
- Lighting and power receptacles
- Pumps and fans that cycle on or off regularly
- Smaller air compressors, refrigeration compressors, and air dryers
- Critical equipment requires manual restart, including:
- Fuel oil pumps
- Boiler feedwater pumps
- Chilled water pumps
- Condenser water pumps
- Boiler draft fans
- Condensate transfer pumps
- Large air compressors
- Refrigeration compressors and chillers
- Air handling unit fans
Valve Response to Power Failure
- Valves fail to a safe position, including:
- Heating system control valves (fail open)
- Fuel line safety shut-off valves (fail closed)
- Fuel line bleed valves (fail open)
- Boiler feedwater regulating valves (fail closed, unless self-powered)
- Operators must ensure fuel safety shut-off and feedwater control valves fail closed to prevent boiler fires and water damage
Plant Response to Power Failure
- Plants without backup power remain "dead" until normal utility power is restored
- Plants with backup power (Emergency Power Supply Systems (EPSS)) have standby generators and automatic transfer switches
- EPSS supplies power to critical equipment, including:
- Control room panels and instrumentation
- Emergency lighting
- Feedwater control valves
- Fuel control valves
- Boiler feedwater pumps
- Condensate pumps
- Turbine seal oil pumps
- Turbine lubricating oil pumps
- Fire water pumps
- Plants with uninterruptable power supply (UPS) systems use batteries and inverters to supply power to critical equipment
Loss of Water Level
- Causes of loss of water level include:
- Feedwater system failure
- Boiler feedwater pump failure
- Control valve failure
- Failure to return condensate to the plant
- Response to loss of water level includes:
- Checking feedwater pump discharge pressure
- Starting standby feedwater pump
- Venting and priming standby pump
- Checking valves and piping for blockages or damage
- Checking boiler water level and adjusting feedwater flow accordingly
Boiler Trips and Response
- Boiler trips on low water due to failure of feedwater system or boiler
- Response to boiler trip includes:
- Closing pilot and main test firing valves
- Closing non-return valve and header valve
- Opening non-return valve drain
- Not restarting boiler until cause of feedwater loss is rectified
- If boiler sustains a low water condition, it must be shut down, cooled, and inspected for damage### Flame Failure Signals and Causes
- Flame failure signals do not result from boiler permissives, such as low water cut-off, fuel pressure switch, or pressuretrol.
- When a flame failure occurs, the pilot and main test firing valves should be shut, and the cause of the failure should be investigated.
Inadequate Pilot Flame
- Inadequate pilot flame can occur during the pilot trial for ignition (PTFI) period if the pilot is too small to light the main burner.
- Causes of inadequate pilot flame include:
- Defective or improperly adjusted pilot fuel regulator
- Excessive combustion air provided during the PTFI period
- ASME CSD-1 recommends an annual pilot turndown test to establish the minimum pilot flame size that can consistently and safely ignite the main burner.
- A certified burner mechanic, such as a Class A gas fitter, must perform the test and adjust the pilot flame.
Unstable Main Flame
- Causes of unstable main flame include:
- Excessive fuel pressure
- Inadequate fuel pressure
- Excessive combustion air
- Inadequate atomizing air or steam
- Dirty atomizer spray plate
- Defective fuel pumps
- Blocked fuel strainers
- Utility gas supply failure
Excessive Fuel Pressure
- Causes of excessive fuel pressure include:
- Improperly adjusted fuel pressure regulator
- Effects of excessive fuel pressure include:
- Over-firing
- Lifting flames
- Smoky furnace conditions
- Flame instability
- A certified burner technician, oil fitter, or Class A gas fitter should adjust the fuel pressure and the high fuel pressure cut-off to the burner manufacturer specifications.
Inadequate Fuel Pressure
- Causes of inadequate fuel pressure include:
- Improperly adjusted fuel pressure regulator
- Failure in the utility fuel supply system (for oil burners)
- Blockage in the fuel strainer (for oil burners)
- Defective fuel oil pump
- Effects of inadequate fuel pressure include:
- Flame instability
- Remedies for inadequate fuel pressure include:
- Checking the fuel oil supply pressure
- Switching strainers (for oil burners with dual strainers)
- Cleaning the fuel strainer (for oil burners with a single strainer)
- Suspecting a faulty pump and switching to the standby fuel oil pump
Learn about the procedures to follow when a flame failure occurs in a boiler, including shutting off pilot and main test firing valves, investigating the cause, and testing flame safeguard controls before restoring the boiler to service.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
