Chapter 92- Gas Burners For Heating Boilers Flashcards
Gas is already in a vapour state, so further vaporization or atomization isn’t necessary so what does the gas burner accomplish
It provides a complete and turbulent mixing of gas and combustion air
There are two classifications of gas burners what are they
Pre mix burner
After- mix burner
Define a premix burner
Combustion air is mixed with gas inside the burner
Define an after mix burner
Combustion air is mixed with the gas after it leaves the burner
Is a atmospheric burner a pre mix or after mix burner
Pre mix
The pre mix percentage in an atmospheric affects what
Increased air entering the nozzle shortens the flame giving it an inner green color. because of faster burning, if air is too high the flame may retreat back into the tube.
Burner heads maybe
A variety of shapes and sizes depending on there application
What is the most common type of burner head?
The rectangle type used in heating boilers
What is the most common application of a refractory type burner
Fire tube boilers
A major advantage of a refractory burner
Air and fuel are preheated raising efficiency and lowering the need for excess air
Disadvantage of a refractory burner
More complex, higher cost
Ring burner pre mix or after mix
After mix
What do deflector rings in a ring burner accomplish?
Provide intimate mixing of the air and fuel
Advantage of natural gas
Storage is not required for fuel as it is pipelined in
Disadvantage of natural gas
If interruption in the gas supply occurs then the plant will shut down
An atmospheric burner has air entering around the burner, which is termed
Secondary air
The amount of premix air to an atmospheric burner should be
30- 40%
A refractory burner disadvantage is
High initial cost
A very common packaged oil has burner is the
Ring burner
An atmospheric burner head which is very popular on heating boilers Is the
Rectangular burner
Atmospheric burners are used for
Gas stoves
Hot water heaters
Heating furnaces
An intermittent pilot
Lights the main flame and remains on with it
A continuous pilot is also known as a __________ pilot
Standing
What type of pilot lights the main burner and then shuts off?
Interrupted
An example of the after mix burner is the
Ring burner
A hydra motor valve
Is slow to open and quick to close
A solenoid gas fuel valve
Is held closed by fuel pressure
Diaphragm gas valves use________ to open the valve
Gas pressure
What type of gas valves incorporates a relay coil and a gas bleed port
A diaphragm gas valve
Larger solenoid type oil and gas valves usually delayed opening to prevent
Puff back
