Fans And Dynamic Compressors Flashcards

1
Q

What is combination flow or multi flow compressors?

A

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.

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2
Q

What does surge mean?

How is it controlled?

A

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.

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3
Q

What does stonewalling mean?

A

Has has reached speed of sound. It’s maximum velocity. It can’t go faster so it slows down.

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4
Q

What are the 3 types of centrifugal fan blades?

Which is the most efficient?

A

Solid flat

Forward curved

Air foil, most efficient.

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5
Q

What are 2 types of axial compressor rotors?

Which is the strongest?

A

Drum

Solid disc, strongest

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6
Q

What are the 3 types of mechanical drafts?

Give examples of each.

A

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.

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7
Q

Large single suction fans are generally mounted on what type of bearing?

A

Double row spherical roller bearings.

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8
Q

What are 3 pressures fans develop?

How are they read?

A

Static pressure

Velocity pressure

Total pressure

Read by manometer

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9
Q

What is static pressure?

A

The air pressure on the inside of the duct walls or pipping.

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10
Q

What is velocity pressure?

A

Is the pressure over and above static pressure.

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11
Q

What happens to velocity and pressure when air is converged?

A

Velocity increases so pressure also increases.

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12
Q

What does a “hunting” fan mean?

How is hunting made?

A

Hunting is where the fan sounds like it’s breathing.

Back pressure is system crates the hunting effect.

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13
Q

Where are carbon ring seals?

Where are they located?

A

Used where there are low pressure differentials.

On shaft between casing and bearing housing.

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14
Q

What are 3 types of thrust control?

A

Thrust bearings

Balanced drum

Impeller arrangements

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15
Q

Where would you use sectional casing compressors?

A

Usually on units with low pressure ratios and small volumes.

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16
Q

What are 3 different designs of compressor casings?

A

Sectional

Horizontally split

Vertically split

17
Q

What do diaphragms do in a compressor?

A

Directs discharge gas from one impeller to the eye of the next.

18
Q

What do inlet guid vanes do?

A

Control output and efficiency

By throttling inlet gas flow

19
Q

What are 3 types if impellers used in compressors?

A

Open

Closed

Semi closed

20
Q

Single stage compressors deliver what types of air?

A

Large amounts if air at low pressure.

21
Q

What applications are vertically split casing used for?

A

High pressure applications

Up to 10,000 psig

22
Q

Horizontally split casings are usually limited to how many psi?

A

Horizontally split casing ms are usually limited to less than 1000 psig.

23
Q

Dynamic compressors use impellers to impact _____ energy into the gas stream.

A

Kinetic energy

24
Q

What are some types of cooling towers?

A

Atmospheric ( using natural draft)

Mechanical, forced draft and induced draft.

25
Q

What do some manufactures put in a tube axial fan to reduce swirl?

A

A channel in discharge to reduce swirling in duct.

26
Q

What are the 3 main groups for axial flow fans?

A

1: propeller fans
2: tube axis fans
3: vane axis fans

27
Q

What application would you use radial fan blades?

A

High speeds, high pressure

28
Q

Compare forward blade fans speed and volume to a backward inclined blade fan.

What application is a forward blade used?

A

Forward blade is slower speed for same amount of volume.

Low operating speeds make then quite limited to clean services, low pressures.

29
Q

What is used to prevent pitting is a bearing and used to ground a build up of static electricity?

A

Static arrests

Ex: ground brush touching the shaft.

30
Q

What is the formula for calculating the curet duct length for laminar flow?

A

Squat root of 4ab/ pie

31
Q

A scoop tube is a type of what?

A

Hydraulic clutch