Hydrocarbon Compression

DYNAMIC COMPRESSORS

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There are two forms of energy in any system. One is called potential energy and the other is called kinetic energy. For example, compressed gas in a static state exerts its pressure in all directions, as shown in Figure 1.8. When the outlet valve is opened, the gas flows out at very high velocity. Depending on the flow rate, the pressure in the cylinder drops down. In this case, the pressure energy is converted into kinetic energy. This kinetic energy is capable of doing work such as driving a pneumatic wrench, hammer, etc. The higher the pressure, the higher will be the velocity and hence the kinetic energy of the gas leaving the system.

A dynamic compressor adds energy to gas in the same manner that an electric fan does. Consider a fan in operation and note the following points:

1. It is the rotating blades of the fan that force the air to move.
2. Air that is at rest tends to remain at rest.
3. As the fan blades start turning, they push on the air. The stationary air resists the push of the blades.
4. As the air resists the blades, the molecules of the air are brought closer together.
5. When the air molecules are compressed, the volume of the air decreases.
6. As the volume of the air decreases, its pressure increases.
7. The blades of the fan overcome the resistance of the air and thrust the air forward.
8. The faster the blades turn, the faster the air is pushed.
9. The fan, by doing work on the air, actually increases the pressure and velocity of the air.
10. When velocity and pressure are added to a gas, its total energy increases.
11. A dynamic compressor increases the total gas energy by adding pressure and velocity to the gas.
12. The total energy of a gas leaving a compressor is greater than the total energy of the gas entering the compressor.
13. The energy that a gas gains in a compressor is due to the work done on it.

1 6 DYNAMIC COMPRESSORS

Written by Jack

October 1st, 2021 at 1:11 am

Posted in Fundamental

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