Centrifugal compressor (Api 617)

Centrifugal compressor is a type of dynamic compressor and it is come in the categories of turbo compressor. Dynamic compressor also called turbo compressors and it is classified into two part, one is axial compressor and radial compressor (Centrifugal compressor) on the basis of designs. 

Where more horse power required for operation then dynamic compressor is a best choice and it is work on the constant pressure with variable flow but whereas in the positive displacement type compressors flow fixed and variations in pressure.

There are major factor for selection the dynamic compressor that is performance of dynamic compressor is dependent on the external condition of the systems like change in the temperature, density of fluid, that will effects on the centrifugal compressor.

IMPELLER ASSEMBLY

Compressor driver

The driver is the part of a compressor package that supplies the power to the compressor. It can be an electric motor a steam turbine. Gearbox is often used between the driver and compressor to allows the compressor to run at a different speed than the driver. This gearbox may either be a part of the compressor casing or it might be in separate housing.

Coupling

  Couplings are used to connect two shafts of gearbox, compressor and driver. The drivers connected to the compressor or gearbox through either a flexible diaphragm coupling or a gear coupling that also allows very small misalignment between the two rotating parts. Some time hydraulic coupling are used to connect the shaft of compressor, gear box and driver and it is play important role in operation of any type of rotating package.

Dry gas seal

Dry gas seal is also a important part of compressor package because it prevent gas leakage come out from rotating part of equipment like shaft throughout. most centrifugal compressor packages include a seal oil system and a lube oil system. Sometimes a gas cooling system is also part of the overall package. This is Major components of the compressor package. 

TRUST BEARING

what part use in centrifugal compressor?

Part of centrifugal com pressure

There are many part are use in compressor to complete assembly, some of part are mentioned below. Casing (split casing, vertically split, horizontally split, or barrel type casing), shaft assembly (shaft, impeller, labyrinth seal, bearing, balancing disk, balancing drum, dry gas seal, diaphragm diffuser, impeller vans, outlet and inlet nozzles).

What is casing of centrifugal compress?

The casing is a static part of any equipment and it is very important because all the pumping and pressurization activity happens within it.

What type of casing use for centrifugal compressor.

Type of casing is described below

Mainly three type of casing use for it, The description are below  mentioned.

The casing are the stationary part of the compressor. The two most important part of casing are the inlet guide  and diffuser or discharge volute.

What is rotar assembly?

The rotor assembly to the motor assembly connected with a coupling and one or more impellers mounted on the shaft as the rotor assembly rotates each impeller delivers energy to the gas. Rotor assembly is supported by bearings, the bearing prevents the forward and backward, axial movement, side-to-side and radial movement of the shaft and impeller.

What is Lube oil system in centrifugal compressor?

Lube oil system in centrifugal compressor

A lube oil system provides a necessary lubrication to the bearings of the compressor often the same lube oil system will provide lubrication to driver, gear box and couplings. Some time lube oil system is a internal part of package and in some other case lube oil provided by external sources or separate lube oil package (skid).

What is dry gas seal?

Dry gas seal 

Dry gas seal are  prevent the compressed gas from leaking out around the shaft in addition to seals those compressors have a seal oil system to further limit gas leakage. This seal oil system can either be a separate system or part of the lube oil system. Some time nitrogen is use for buffer gas.

What is working principle of centrifugal compressor?

How centrifugal compressor works?

What is working principle of centrifugal compressor?

Working of centrifugal compressor

When gas enters in to the compressor several forces are acting on the gas. One of these forces is aerodynamic force. The aerodynamic force is the same force that causes an airplane wing to lift as it moves through the air this lifting force helps to move the gas from low pressure at the eye of the impeller to high pressure at the outer edge of impeller.

Another forces is centrifugal force, centrifugal force is the same outward force that try move away from the center higher outward force that can throw them off the right gas enters the compressor through the suction port and is directed to the centre of the impeller.

As the impeller rotates the circular motion generates the forces that lift and move the gas away from the centre of the impeller as well as creating a suction at the centre of the impeller because the outside edge of the impeller travels faster than the centre of the impeller.

The centrifugal force increases its speed as it moves outward. Centrifugal force increases the motion energy to pressure energy of the gas. As the gas leaves the outside edge of the impeller. and then it enters an area of the casing called a diffuser or volute.

What is diffuser in centrifugal compressor?

What is role of diffuser in centrifugal compressor?

Role of diffuser in centrifugal compressor

The diffuser is stationary part of the casing assembly, diffuser are design so that the flow area increases as the gas leaves the impeller; this increased area allows the gas to slow down or decrease in velocity as the gas flows down.

The motion energy is converted into pressure energy by diffuser. Finally, when the gas leaves the centre combination of all these forces centrifugal force, aerodynamic force and change in velocity, produced gas discharge pressure that is several times higher than the suction pressure. 

What is Multistage centrifugal compressor?

Why Multistage centrifugal compressor used in industries?

So generally, the pressure produced by one impeller won’t be enough to meet many oilfield. This is why multistage and typical compressor are most often used.

Multistage centrifugal compressors are formed by joining several impellers together, each separated from the others by a diaphragm. 

What do you mean by compression stage?

Compression stage

Sometimes one impeller and one diaphragm define a stage. In other cases, however, a stage is defined from the beginning of a suction port to the end of a discharge port in this case. The stage could have more than one impeller in it. 

In any case the gas leaving one stage will always be at a lower pressure than when at least the next stage in this way pressure is increased in each stage until the final pressure is reached.

And most of stage compressors the gas leaving an impeller of one stage flows through a shaft and around a diaphragm is then directed by the inlet guide into the eye of the next impeller.

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