Chapter 7 Flashcards
Draft is defined as:
A) The difference between atmospheric pressure and the boiler internal pressure
B) The amount of air flow through the furnace from the burner to the stack
C) The difference between atmospheric pressure and the furnace/firebox pressure
D) The boiler furnace pressure during start up
C
An induced draft fan is located in the flue gas path:
A) In front of the economizer
B) Between the boiler and the stack
C) Between the Economizer and the Air heater
D) In front of the Air heater
B
With natural draft, the boiler furnace/firebox:
A) Is kept at a slightly negative pressure
B) Is kept a a slightly positive pressure
C) Is kept at a balanced pressure
D) Is kept at atmospheric pressure
A
With a forced draft fan the boiler furnace/firebox:
A) Is kept at a balanced pressure
B) Is kept at a slightly positive pressure
C) Is kept at atmospheric pressure
D) Is kept at a slightly negative pressure
B
Control of balanced draft primary and secondary louvers are located:
A) At the suction side of the FD and ID fans
B) Between the Fans and the Air Heater
C) Between the Boiler and Air Heater
D) At the outlet side of the FD and ID fans
C
The most efficient fan output control is:
A) Inlet damper and vanes control
B) Variable Speed Drive control
C) On/off control
D) Outlet damper control
B
Primary air is defined as air that:
A) Is usually mixed with the fuel immediately upon leaving the fuel nozzle
B) Is air that is supplied to the burner downstream of the primary zone
C) Is air that enters the burner around the outside of the primary combustion nozzles
D) Is air that passes through the louvers/registers
A
All pulverized coal steam generators use Electrostatic Precipitators to remove fly ash from the flue gas stream. The EP relies on the principle that:
A) Ash particles receive a negative electrical charge and become attracted to the positively charged collector wall
B) Ash particles receive a positively electrical charge and become attracted to the negative charged collector wall
C) Ash particles receive a negative AC electrical charge and become attracted to the positively charged collector wall
D) Ash particles receive a positively AC electrical charge and become attracted to the negative charged collector wall
A
To prevent Electrostatic Precipitators clogging and shorting out of electrical charge:
A) A water spray is used to wash the EP walls
B) The collector rods electrical charge is change from DC to AC or reversed thus dropping the ash particles
C) A device called a Rapper is used to dislodge the ash particles
D) Air is blown through the passages
C
To aid in the removal of fly ash and reduce the volume of ash particulate from the flue gas stream on coal fired units, one or more____________ are installed ahead of the electrostatic precipitator.
A) Particle Precipitators
B) Bag house filters
C) Cyclone Precipitators
D) Mechanical Scrubbers
C
Bag house filters are normally used:
A) When Sulphur Dioxides (SO2) creates corrosion problems
B) When ash particulates are 5 microns of smaller
C) When disposal of ash content is under environmental restrictions
D) When Electrostatic Precipitators are ineffective
D
Unlike the Pneumatic Fly Ash removal, SO2 wet and dry scrubber systems, the Submerged Scrapper and Wet Type Bottom Ash Hopper systems require a:
A) Clinker Grinder
B) Mechanical Exhauster
C) Sluice Gate
D) Fly-ash Silo
A
