Cyclone separators are used to remove liquid particles from a gas stream, normally before the gas send to a compressor. They are the same or similar to the scrubber provided at the inlet of a compressor.
The inlet gas stream is allowed to enter the separator at a tangential direction. In some cases a swirl tube will be provided to increase the centrifugal action. When the gas stream enter the vessel at a tangential direction it swirls( cyclonic effect) around and heavier liquid drops falls down and gas particles moves up. This is due to the difference in centrifugal force generated due to the cyclonic effect.
Centrifugal force will be more on large and heavy particles. So liquid particles with a higher centrifugal force get separated from gas very easily. Gas particles which are lighter moves up with the additional centrifugal force received due to the cyclonic effect. The shape of the cyclone separator gives enough time for the gas to drop down the entrained liquid particles while it moves up.
What is the importance of the pressure in the separator ?
Separator pressure is to be maintained at the normal operating range because of many reasons.
The flow of fluid from one end to another end of a pipeline is proportional to the difference in the pressure. If we want to move a fluid from `A` to `B` thenwe should have a higher pressure at A than at B. Flow of fluids from `A` to `B` can be increased either by increasing the pressure at `A` or reducing the pressure at `B`.
Let us think that the location `A` is wellhead and location `B` is the separator. So if we increase or decrease the pressure in a separator, it will effect the production rate. If we reduce the pressure in the separator vessel, we can increase the production or flow through the flow line, but we will not be able to send the gas and liquid from the separator to the next processing section.
If we are increasing the separator pressure then the load on the pumps
( ESP, Beam Pump or PCP ) has to be increased to maintain the same flow. So we have to keep an optimum pressure in the separator. This pressure should be sufficient to push the liquid to the next processing section and supply gas to compressors at the required suction pressure and same time maintaining the load on pumps. Separator pressure effects the rate of separation also. If the pressure is reduced then more gas will be separated. The rate of separation of oil and water also effected by the changes in the separator pressure. So it is important to maintain the separator pressure at the normal operating range.