Dynamic Compressors

Question 1

How do dynamic compressors produce pressure?

Answer 1

They convert velocity into pressure using diffusers, a volute casing or a combination of the two.

Question 2

What can be done to increase the efficiency of a single stage compressor?

Answer 2

Diffuser vanes inside the housing allow you to achieve a slightly higher compression ratio.

Question 3

What has to be done to increase the volume and overall pressure ratio of a centrifugal compressor?

Answer 3

You should add additional impellers and their individual diffuser sections to the rotor shaft

Question 4

Name the three casing designs in dynamic compressors.

Answer 4

• sectional
• horizontal split
• vertical split

Question 5

Which casing design do you use for high-pressure applications 10,000 psig?

Answer 5

The vertical split design

Question 6

Name the three styles of impellers and centrifugal compressors

Answer 6

• Open
• Semi-open/closed
• closed

Question 7

Which impeller design provides the highest pressure ratio?

Answer 7

Closed impeller design

Question 8

State the purpose of the guide vanes.

Answer 8

The purpose of the guide vanes is to control or convert the gas flow either into the compressor or from one stage to another

Question 9

What causes axial thrust in a dynamic compressor?

Answer 9

It is the result of the differential pressure between the impeller front and the back shroud surfaces

Question 10

What are three ways that you can axial thrust?

Answer 10

• thrust bearings
• balance Pistons or drums
• opposing gas flows

Question 11

What is one of the most commonly used seal types and dynamic compressors?

Answer 11

-The labyrinth seal

Question 12

How does the most common seal prevent leakage?

Answer 12

It allows small pressure drops through each stage

Question 13

What three other types of seals can you find in dynamic compressors?

Answer 13

• carbon ring
• Oil or wet seals
• dry gas seals

Question 14

List the five factors that influence the selection of a prime mover

Answer 14

• speed range
• available power
• HP requirements
• economic considerations
• customer preferences

Question 15

What type of compressor has aerodynamically shaped plates?

Answer 15

Axial flow compressors

Question 16

What is the simplest way to control the compressor output?

Answer 16

With a variable speed drive

Question 17

Other than variable speed drive what other method is available for compressor control?

Answer 17

Varying the position of the stater blades

Question 18

Which instrument can be used to inspect the internal components without removing the casing covers?

Answer 18

A borescope

Question 19

What do you call slow reversal in a compressor?

Answer 19

Surge

Question 20

Dynamic compressors work on what law?

Answer 20

Bernoulli’s principle

Question 21

An axial compressor operating at a higher altitude will

Answer 21

Take longer to fill a compressor air system

Question 22

What would be necessary in order for a gas to flow from one area to another?

Answer 22

There must be a pressure differential

Question 23

Stonewalling (choke) describes a condition in which?

Answer 23

Maximum flow and velocity has been achieved

Question 24

Surge occurs when?

Answer 24

Floor versus through an axial compressor

Question 25

In the radio compressor_______________ maybe used to convert velocity pressure.

Answer 25

Diffuser

Question 26

Controlling compressor output by restricting the inlet flow is called?

Answer 26

Suction throttling

Question 27

Dynamic compressors using colors to impart__________ Energy to the gas stream.

Answer 27

Kinetic

Question 28

Single stage compressors in industry are commonly used to:

Answer 28

Deliver high-volume, low-pressure gas

Question 29

What is the advantage game by using a multi flow compressor?

Answer 29

Greater velocity increase

Question 30

What are two major classifications of dynamic compressors?

Answer 30

• Axial

- Centrifugal