Fans And Dynamic Compressors Flashcards
What is combination flow or multi flow compressors?
Having 2 or more types of impellers in a compressor.
Ex: 5 stages of axial, then going into centrifugal impellers to achieve discharge pressure easier.
What does surge mean?
How is it controlled?
Compressed far rushing from discharge back to inlet.
Controlled by a recycling valve, which directs the gas back to tank. Or a surge valve, which will release the gas to atmosphere.
What does stonewalling mean?
Has has reached speed of sound. It’s maximum velocity. It can’t go faster so it slows down.
What are the 3 types of centrifugal fan blades?
Which is the most efficient?
Solid flat
Forward curved
Air foil, most efficient.
What are 2 types of axial compressor rotors?
Which is the strongest?
Drum
Solid disc, strongest
What are the 3 types of mechanical drafts?
Give examples of each.
Forced draft, fan is forcing air into furnace.
Induced draft, fan is blowing air out of the furnace.
Balanced furnace, blowing air in and sucking air out.
Large single suction fans are generally mounted on what type of bearing?
Double row spherical roller bearings.
What are 3 pressures fans develop?
How are they read?
Static pressure
Velocity pressure
Total pressure
Read by manometer
What is static pressure?
The air pressure on the inside of the duct walls or pipping.
What is velocity pressure?
Is the pressure over and above static pressure.
What happens to velocity and pressure when air is converged?
Velocity increases so pressure also increases.
What does a “hunting” fan mean?
How is hunting made?
Hunting is where the fan sounds like it’s breathing.
Back pressure is system crates the hunting effect.
Where are carbon ring seals?
Where are they located?
Used where there are low pressure differentials.
On shaft between casing and bearing housing.
What are 3 types of thrust control?
Thrust bearings
Balanced drum
Impeller arrangements
Where would you use sectional casing compressors?
Usually on units with low pressure ratios and small volumes.
