3 replies to this topic

[ethanhan]

Hi dear all experts

I would like to understand how the Stage separator's pressure can be reduced from HP to LP ? Second, is it separator's pressure equal to fluids vapour pressure?

Regards
Ethanhan

[djack77494]

I would like to understand how the Stage separator's pressure can be reduced from HP to LP ? Second, is it separator's pressure equal to fluids vapour pressure?

Ethanhan,
I assume you are referring to separators as used in oil and gas production. As the fluids leave the reservoir and flow to your first (high pressure) separator, gas is released from the liquids and separated. Water and oil (and sand) also seperate. Typically you are not applying significant heat to the produced fluids, and you are not striving for a liquid-vapor equilibrium situation as you would have, for example, in subsequent distillation processes. It's more a matter of releasing dissolved gases rather than generating vapors. I think this answers your second question, but I'm not sure how to respond to the first. Pressure is controlled by controlling the venting of the gases that are released, and liquids are then "let down" from one separator to the next (lower pressure) separator under level control.

[ethanhan]

Djack77494

Thanks for your reply. However, how to set the operating pressure at LP or HP? Any consideration? how to get know whether it is equilibrium state?

[djack77494]

A major factor in all this will be consideration of the gas compressor(s). Certainly, you could set the pressures at any level you'd like. But you want levels that make sense when it comes to the compressor. Very simplistically, let's say your final stage of dewatering is at 1.5 bar[A], and that you aim for having a compression ratio of 3. So your low pressure seperator would operate at a bit over (3*1.5) = 4.5 bar[A]. Similarly, the high pressure separator would operate (3*4.5) = 13.5 bar[A]. Of course this is an extremely simplified example, and other considerations come into play.

I'm not sure what you mean about equilibrium. In general, you would have one equilibrium stage for each separator.