Combustion and Draft Flashcards
Insufficient air for combustion will result in:
- Sulfur monoxide in the flue gases
- High oxygen reading in flue gases
- Lower than normal oxygen reading in flue gases
- High CO in flue gases
- Higher than normal flue gas temperature
A) 1, 2, 3 B) 1, 3, 5 C) 3, 4, 5 D) 1, 3, 4 E) 2, 3, 4
D) 1, 3, 4
Combustion of a fuel in a boiler furnace:
A) Should be performed with a minimum of excess air
B) Is perfect if there is no moisture in the stack gases
C) Requires a higher air-fuel ratio than a diesel engine
D) Requires a higher air-fuel ratio than a gas turbine
E) Requires mechanical draft
A) Should be performed with a minimum of excess air
Proper draft is important to the plant operator because it:
A) Satisfies the codes
B) Delivers the products of combustion to a high altitude
C) Prevents toxic gases from leaking out of the system
D) Produces efficient combustion
E) Reduces the volume of ash or slag
D) Produces efficient combustion
In a forced draft system, the furnace pressure is:
A) Below atmospheric pressure B) Measured in psi C) Above atmospheric pressure D) At atmospheric pressure E) Not a factor
C) Above atmospheric pressure
A pressurized furnace is usually associated with:
A) Packaged boiler with forced draft B) Natural draft C) Balanced draft D) Large steam generators E) Induced draft
A) Packaged boiler with forced draft
The combustible elements in fuels are:
- Carbon
- Sulphur
- Ash
- Nitrogen
- Hydrogen
A) 1, 2, 5 B) 2, 3, 5 C) 1, 4, 5 D) 1, 2, 3 E) 3, 4, 5
E) 3, 4, 5
Inlet damper control on a fan:
A) Is used on forced draft fans only
B) Is less complicated than an outlet damper control
C) Can only be used when the fan is driven by a steam turbine
D) Regulates the amount of air entering the fan
E) Requires more power to drive the fan when the vanes are closed
D) Regulates the amount of air entering the fan
An induced draft fan:
A) Is physically smaller than a FD (forced draft) fan
B) Operates at much higher temperatures than an FD fan
C) Handles only air
D) Has less expensive materials of construction than an FD fan
E) Discharges air to the windbox
B) Operates at much higher temperatures than an FD fan
A continuous flow of air and gas through a boiler is produced by a:
A) Flow difference B) Specific gravity difference C) Velocity difference D) Pressure difference E) Viscosity difference
D) 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) Odour B) Solids content C) Boiling point D) Colour E) Heating value
C) Boiling point
Combustion air openings are required by code. Combustion air can be said to be:
A) Atomising air
B) All air which contributes to the completion of combustion
C) Excess air
D) All air which enters the boiler furnace including high excess air
E) All air which contacts the raw fuel before the burner
B) All air which contributes to the completion of combustion
What are the advantages of mechanical draft?
- Dependent on atmospheric air temperature
- Independent of the chimney temperature
- A smaller chimney can be used
- More definite draft control is possible
A) 1, 3, 4 B) 1, 2, 3, 4 C) 3, 4 D) 1, 2, 3 E) 2, 3, 4
E) 2, 3, 4
The draft through a natural draft furnace is increased by:
A) Decreasing the height of the stack B) Reducing the firing rate C) Increasing the temperature of the stack D) Warming the outside air E) Decreasing the furnace temperature
C) Increasing the temperature of the stack
Carbon monoxide is both combustible and:
A) Expensive B) Grey in colour C) Inert D) Non-compressible E) Undersirable
E) Undersirable
CO₂ is the chemical symbol for:
A) Carbon monoxide B) Carbon C) Carbonic acid D) Hydrocarbon E) Carbon dioxide
E) Carbon dioxide
