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Flashcards in Dynamic Compressors Deck (27)
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1
Q

Dynamic balancing

A
  • balancing the shaft when it’s rotating
2
Q

Three casing designs

A

-sectional (vacuum), horizontal split, vertically split (high pressure)

3
Q

Three different types of impellers

A

-open, semi-closed, closed (highest efficiencies because of the close tolerances, minimal leakage)

4
Q

Guide Elements/vanes

A

-control and direct gas flow into the compressor or from one stage to the next

5
Q

How do you control thrust in dynamic compressors

A

-balance Pistons, thrust bearings and impeller arrangements (opposing air flows)

6
Q

Balance piston

A
  • located at the discharge end, immediately behind the last impeller.
  • provides a surface area on which the full discharge pressure act.
7
Q

Thrust bearings

A

-

8
Q

Labyrinth Seal

A
  • are installed in the diaphragm assembly to minimize internal leakage along the shaft from the progressively higher stage pressures.
  • seals by allowing a small amount of high pressure gas to escape into the chamber formed by the following ring
9
Q

Drum rotors

A
  • discs that are flanged to fit to each other and are held together with tie bolts and stub shafts that may bolt or press into place.
  • may also be hollow cylinders machines with the blades bolted to them and end covers with welded stub shafts
10
Q

Diaphragm

A
  • separates the impellers in the compressor casing

- they direct flow throw the compressor

11
Q

Axial Compressors

A
  • each stage consist of a number of blades that attach to the rotor and work with corresponding blades on the stator.
  • air flows down the shaft through stationary Stators
12
Q

Blade Fouling

A

-debris for the dirty gases, etc… That stick to the blades

13
Q

Surge

A
  • when low flow causes flow reversal and compressed gas rushed back from the discharge to the inlet, which causes a pressure drop at the discharge
  • controlled by a bypass (air) or recycle valve (gas) which sends air back the the suction drum so pressure is balanced
14
Q

Stators

A

-are a series of blades that attach to the casing wall. They can be fixed or adjustable and solid or hollow

15
Q

Three main parts of Axial flow compressors

A

Rotor, stator and casing

16
Q

Best way to control output

A
  • varying the speed

- varying stator arrangement

17
Q

Surge Point

A

-

-high pressure at the outlet

18
Q

Stonewall

A
  • where max flow and max velocity has been reached

- low pressure at the outlet

19
Q

Multi-flow compressors

A

-gives you the ability to dramatically increase the pressure ratio. For each impeller you add you can reduce 3-4 axial stages

20
Q

Single stage

A

-high volume low pressure

21
Q

Kinetic energy

A

-energy in motion

21
Q

Carbon Seals

A
  • low pressure seals

- often used with labyrinth seals as the final sealing element

22
Q

Beam

A

-multi-stage the rotor being supported by bearings at both ends

23
Q

Impeller arrangements (thrust control)

A

-dual

24
Q

Absolute zero

A
  • 0 rankin and kelvin
  • -273 Celsius (kelvin) think CK Calvin Klein
  • -460 Fahrenheit (rankin)
25
Q

What’s needed at inlet

A
  • outside pressure needs to be slightly higher than 0 for pressure differential to occur. Pressure will always go from high to low.
  • inlet has to be lowest pressure
26
Q

What creates the pressure in a compressor?

A
  • the decrease of air flow throw the diffuser.

- the air being brought in and sped up with the impeller doesn’t create the pressure