Boiler Flame Failure Quiz and Procedures

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

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

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

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

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 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 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.

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.

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