Module G Flashcards
What are the two major classifications of dynamic compressors ?
- Centrifugal
- Axial
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 impeller design provides the highest pressure ratio?
closed impeller design
State the purpose of the guide vanes
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 of the shroud surfaces
Which casing design do you use for high-pressure applications (10 000 psig)
The vertical split design
Name the three styles of impellers in centrifugal compressors.
- Open
- Semi-open /closed
- Closed
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 in 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 preference
