Book 1 Chapter 13: Combustion And Draft Flashcards
(43 cards)
The incomplete combustion of carbon results in the formation of carbon ________________.
A) Tetrachloride
B) Monoxide
C) Dioxide
D) Trioxide
B) Monoxide
When a unit amount of fuel is burned completely, the heat produced is called the ______ of the fuel.
A) Heat content
B) Heating value
C) Excess air
D) Combustion efficiency
B) Heating value
The conditions for complete combustion include __________
A) Low furnace temperature
B) Cool heating surfaces
C) Thorough mixing of water and fuel
D) Enough air
D) Enough air
The amount of air required to supply just enough oxygen for complete combustion is called ______ air.
A) Excess
B) Theoretical
C) Tertiary
D) Primary
B) Theoretical
___________ forms the greatest percentage of the combustible elements in a fuel.
A) Sulphur
B) Hydrogen
C) Carbon
D) Wood
C) Carbon
An advantage of using natural gas as a fuel is:
A) More storage space is required
B) Has less heating value than oil
C) Less expensive than coal
D) Easily mixed with air
D) Easily mixed with air
A draft system that is motorized and mounted on the front of the boiler is _________ draft.
A) Natural
B) Forced
C) Induced
D) Balanced
B) Forced
A pressure explosion of a boiler may occur if:
A) The gas pressure to the burner is too high
B) Feedwater pressure is too high
C) Low boiler water level produces weakening of tubes
D) The safety valve opens too early
C) Low boiler water level produces weakening of tubes
Insufficient air for combustion will result in:
1. Sulfur monoxide in the flue gases
2. High oxygen reading in the flue gases
3. Lower than normal oxygen reading in flue gases
4. High CO in flue gases
5. Higher than normal flue gas temperature
A) 2,3,4
B) 1,3,5
C) 3,4,5
D) 1,3,4
E) 1,2,3
D) 1,3,4
Combustion of fuel in a boiler furnace:
A) Requires mechanical draft
B) Requires a higher air-fuel ratio than a gas turbine
C) Requires a higher air-fuel ratio than a diesel engine
D) Is perfect if there is no moisture in the stack gases
E) Should be performed with a minimum of excess air
E) Should be performed with a minimum of excess air
Proper draft is important to the plant operator because it:
A) Delivers the products of combustion to a high altitude
B) Satisfies the codes
C) Produces efficient combustion
D) Prevents toxic gases from leaking out of the system
E) Reduces the volume of ash or slag
C) Produces efficient combustion
In a forced draft system, the furnace pressure is:
A) Not a factor
B) Measured in psi
C) Above atmospheric pressure
D) Below atmospheric pressure
E) At atmospheric pressure
C) Above atmospheric pressure
A pressurized furnace is usually associated with:
A) Packaged boiler with forced draft
B) Balance draft
C) Natural draft
D) Large steam generators
E) Induced draft
A) Packaged boiler with forced draft
The combustible elements in fuels are:
1. Carbon
2. Sulphur
3. Ash
4. Nitrogen
5. Hydrogen
A) 2,3,5
B) 3,4,5
C) 1,4,5
D) 1,2,5
E) 1,2,3
D) 1,2,5
Inlet damper control on a fan:
A) Is less complicated than an outlet damper control
B) Is used on forced draft fans only
C) Requires more power to drive the fan when the vanes are closed
D) Regulates the amount of air entering the fan
E) Can only be used when the fan is driven by a steam turbine
D) Regulates the amount of air entering the fan
An induced draft fan:
A) Is physically smaller than a FD (forced draft) fan
B) Has less expensive materials of construction than an FD fan
C) Discharges air to the windbox
D) Handles only air
E) Operates at much higher temperatures than an FD fan
E) Operates at much higher temperatures than an FD fan
A continuous flow of air and gas through a boiler is produced by a:
A) Viscosity difference
B) Flow difference
C) Velocity difference
D) Specific gravity difference
E) Pressure difference
E) Pressure difference
The refining process for fuel oils involves separating the crude oil into end products, which have distinguishing characteristics such as specific gravity, viscosity, and:
A) Colour
B) Odour
C) Solids content
D) Boiling point
E) Heating value
D) Boiling point
Combustion air openings are required by code. Combustion air can be said to be;
A) Atomising air
B) All air which contacts the raw fuel before the burner
C) All air which enters the boiler furnace including high excess air
D) All air which contributes to the completion of combustion
E) Excess air
D) All air which contributes to the completion of combustion
What are the advantages of mechanical draft?
1. Dependent on atmospheric air temperature
2. Independent of the chimney temperature
3. A smaller chimney can be used
4. More definite draft control is possible
A) 1,2,3
B) 2,3,4
C) 3,4
D) 1,3,4
E) 1,2,3,4
B) 2,3,4
The draft through a natural draft furnace is increased by:
A) Decreasing the furnace temperature
B) Decreasing the height of the stack
C) Warming the outside air
D) Increasing the temperature of the stack
E) Reducing the firing rate
D) Increasing the temperature of the stack
Carbon Monoxide is both combustible and:
A) Inert
B) Grey in colour
C) Undesirable
D) Expensive
E) Non-compressible
C) Undesirable
CO2 is the chemical symbol for:
A) Carbonic acid
B) Hydrocarbon
C) Carbon monoxide
D) Carbon dioxide
E) Carbon
D) Carbon dioxide
A boiler with only an induced draft fan:
A) Will have a positive furnace pressure
B) Needs a long stack
C) Cannot maintain a stable fire
D) Will have a negative furnace pressure
E) Does need an airtight furnace
D) Will have a negative furnace pressure
