The gas pilot pressure regulator ____ the incoming header gas pressure to ensure a satisfactory pilot flame.
The main gas pressure regulator controls the gas pressure at a ____ setting than the pilot regulator.
A ____ prevents the burner from operating when the gas pressure in the supply line drops below the pressure necessary to maintain a stable flame at the burners.
(D) Low Gas Pressure Cut-off Switch
A low gas pressure cutoff switch _______ the burner from operating when the gas pressure in the supply line drops below the pressure necessary to maintain a stable flame at the burner.
The high gas pressure switch contacts are normally _______ whenever the main gas line pressure is below a preset pressure.
The main gas valves are ON/OFF, normally open, single-seated gas valves, when the electric motors on the valves are energized.
There are several more common designs of gas burners used for steam generation.
1. Multi-Spud Burner
2. Low Flow Burner
3. Turbulent Flow Burner
4. Ring Type Burner
5. High Efficiency Low NOx Burners
Each spud on a multi-spud burner is equipped with a ____ so that it may be removed for cleaning.
(C) Shut Off valve
Most burners have the fuel entering the combustion air stream at or near a ______ angle to promote good mixing.
The multi-spud burner has ______ spuds or jets connected to a circular manifold.
In a multi-spud burner, each spud is equipped with a ______ valve so that it may be removed for cleaning.
The nitrogen and oxygen in the combustion air ______ at high temperatures to form NOx.
The main function of a gas burner is to:
A. Provide for intimate mixing of gas and combustion air
The thermal NOx reaction occurs rapidly above _____ °C.
To achieve lower NOx the flame temperature must be kept as low as possible. This is achieved by:
D. A & C
The above ground storage must have an earth or concrete dyke around the tank of such a size as to contain the total volume of oil stored plus one _____.
An oil storage tank must not have galvanized pipe, as sulphur in the oil will react with the galvanizing zinc causing _______.
The tank steam smothering line is used in the event of ____.
The heating of heavy fuel oil takes place in ___ stages.
The second stage of heating, to allow atomization of the oil, involves heating the oil to between _________ C.
A. 70 and 100
Failure to burn a fuel oil at the correct pressure and temperature and with the correct atomizer will result in:
1. Flame sputtering
2. Carbon formation
3. Flash back
D. 1, 2, 3, 4
The main function of an ____ is to change the liquid into a fine mist or vapor-like state and then thoroughly mix this “vapor” with air so that combustion can take place quickly and efficiently.
(C) Oil Burner
The atomizing steam for a steam atomizing burner must be dry because moisture causes ____.
(g) Higher Combustion Temperature
Which of the following burners supplies oil under high pressure:
D. Mechanical atomizing
The steam atomizer type burners operate on the principle of producing a steam-fuel emulsion that atomizes the oil through the rapid _______ of the steam when released into the furnace.
The advantages of steam atomizing is:
1. A low turn down ratio is possible
2. A high turn down ratio is possible
3. Low pressure may be used
4. A constant pressure may be maintained from low to high firing condition
D. 2, 3
Steam atomizing burners require cleaning:
D. Less often than mechanical atomizers
In an air atomizing oil burner the air is called:
D. Primary air
The cup of a rotary cup oil burner rotates at:
A) 3 500 rpm
Coal belt conveyors are built with a maximum incline of about ____ depending upon the coal built.
(D) 18 Degrees
The purpose served by the coal ______ is to receive the incoming coal supply, place it on stock, and then transport it from stock to boilers at the time and in the form required.
The coal is fed to the surge bin, where in-line ______ remove any metal.
A belt scale operates by measuring the speed of the belt and the weight on a suspended section of the carrying run. An ________ relates running weights to belt travel and records the tonnage of coal handled.
Screens are fitted in the coal route to the bunkers to remove timber, stone, and oversize coal so that the supply to the ________ mills is kept free.
Reserve Storage coal, stocked for extended periods in the open air it will __________ by weathering and also there is an ever present danger of spontaneous combustion.
The temperature of the stock should be monitored as temperatures of ___ C and above indicate the threat of fire.
There are three general firing arrangements:
G. A, B, C
The secondary air is admitted to the burner housing surrounding the central nozzle through adjustable _____.
Horizontal firing pulverized coal burners the burner(s) are located in the front wall and the flame travels ____ across the furnace.
In a vertical firing arrangement the burners are located in the furnace arch (top) and fire vertically ________.
The tangential firing arrangement has burners installed in each of the ______ of the furnace.
The cyclone furnace burns crushed coal up to ____ size rather than pulverized coal.
In a tube or ball mill pulverization of coal is achieved through continual cascading of the mixture, results from:
A tube (or ball) mill is a hollow cylindrical shell, filled, approximately half full, with forged steel or cast alloy balls, ranging in diameter from ___ mm to ___ mm.
C. 25, 51
Coal pulverizes are commonly called ____.
High-speed impact pulverizes (turning at 1200 to 1800 r/min) consist of a series of hinged or fixed ____ revolving in a chamber.
The bowl mill has ______ to grind the coal between themselves and a slowly rotating horizontal table
Using preheated air with pulverized coal:
B. Dries the coal
In an underfeed stoker, air for combustion is supplied to a chamber below the grates, then it passes through the grates via:
An overfeed stoker uses the _____________ flow of fuel and air, with fuel flowing downward and air flowing upward.
A spreader stoker distributes the coal onto the surface of a traveling grate with ash discharged at the ______ of the furnace.
In a ________ stoker, altering the position of the spill plate or the speed of the rotor changes the distance the coal is thrown.
In a ________ stoker, air for combustion is supplied by a forced draft fan and passes up through openings in the grate to the fuel.
The types of grates used on a crossfeed stoker are:
1. Roller grate type
2. Chain grate type
3. Bar grate type