Dynamic Compressors Flashcards
How do dynamic compressors produce pressure?
They convert velocity into pressure using diffusers, a volute casing or a combination of the two.
What can be done to increase the efficiency of a single stage compressor?
Diffuser vanes inside the housing allow you to achieve a slightly higher compression ratio.
What has to be done to increase the volume and overall pressure ratio of a centrifugal compressor?
You should add additional impellers and their individual diffuser sections to the rotor shaft
Name the three casing designs in dynamic compressors.
- sectional
- horizontal split
- vertical split
Which casing design do you use for high-pressure applications 10,000 psig?
The vertical split design
Name the three styles of impellers and centrifugal compressors
- Open
- Semi-open/closed
- closed
Which impeller design provides the highest pressure ratio?
Closed impeller design
State the purpose of the guide vanes.
The purpose of the guide vanes is to control or convert the gas flow either into the compressor or from one stage to another
What causes axial thrust in a dynamic compressor?
It is the result of the differential pressure between the impeller front and the back shroud surfaces
What are three ways that you can axial thrust?
- thrust bearings
- balance Pistons or drums
- opposing gas flows
What is one of the most commonly used seal types and dynamic compressors?
-The labyrinth seal
How does the most common seal prevent leakage?
It allows small pressure drops through each stage
What three other types of seals can you find in dynamic compressors?
- carbon ring
- Oil or wet seals
- dry gas seals
List the five factors that influence the selection of a prime mover
- speed range
- available power
- HP requirements
- economic considerations
- customer preferences
What type of compressor has aerodynamically shaped plates?
Axial flow compressors
What is the simplest way to control the compressor output?
With a variable speed drive
Other than variable speed drive what other method is available for compressor control?
Varying the position of the stater blades
Which instrument can be used to inspect the internal components without removing the casing covers?
A borescope
What do you call slow reversal in a compressor?
Surge
Dynamic compressors work on what law?
Bernoulli’s principle
An axial compressor operating at a higher altitude will
Take longer to fill a compressor air system
What would be necessary in order for a gas to flow from one area to another?
There must be a pressure differential
Stonewalling (choke) describes a condition in which?
Maximum flow and velocity has been achieved
Surge occurs when?
Floor versus through an axial compressor
In the radio compressor_______________ maybe used to convert velocity pressure.
Diffuser
Controlling compressor output by restricting the inlet flow is called?
Suction throttling
Dynamic compressors using colors to impart__________ Energy to the gas stream.
Kinetic
Single stage compressors in industry are commonly used to:
Deliver high-volume, low-pressure gas
What is the advantage game by using a multi flow compressor?
Greater velocity increase
What are two major classifications of dynamic compressors?
- Axial
- Centrifugal
