How does membrane separation for oil and gas recovery operate? Key points of synergy among absorption, membrane separation, and condensation stages

Membrane separation for oil and gas recovery is not a single device working, but a combination of absorption, membrane separation, and condensation stages. The recovery effect of the whole machine will fluctuate depending on which operating condition deviates.

Absorption section: Stabilize the membrane concentration

Wash the high concentration oil and gas with lean oil in the absorption section first, and control the hydrocarbon concentration on the membrane side within the suitable range of the membrane material. The concentration is too high, the upstream partial pressure difference of the membrane is increased, and the recovered liquid carries oil; If the concentration is too low, the gas burden on the membrane section increases, and the power consumption of the vacuum pump increases. In daily life, it is necessary to check the liquid level of the absorption tower and the pressure of the circulation pump. If the liquid level fluctuates greatly, it is difficult to stabilize the inlet concentration.

Membrane separation section: driven by pressure difference

Membrane modules work according to the principle of dissolution diffusion, where hydrocarbon molecules preferentially pass through the membrane and accumulate on the permeate side before returning to the absorption or condensation section. The working pressure of the membrane segment has a recommended range. If the inlet pressure is too high, it will accelerate membrane aging, while if it is too low, the permeation driving force will be insufficient. The operation record should retain two values: membrane pressure and permeation side vacuum degree. If there is a deviation from the recommended range, the valve position and pump status should be checked.

Condensation section: Put the condensate pipe up

The condensation section is responsible for liquefying and recovering the enriched oil and gas, and the liquid level and discharge valve of the condensate tank are the key inspection points. If the condensate is not discharged in time, the liquid will be carried downstream by the airflow when the tank is full, affecting the membrane components; The discharge valve is stuck, and the accumulated condensate will also reach the heat exchange surface, lowering the condensation temperature.

What to inspect

Regularly check three sets of numbers every day: inlet and outlet membrane pressure difference, condensation temperature, and condensate tank liquid level. Combined with the weekly recycling liquid ratio comparison, the operating status can be basically understood. If there is a decrease in the amount of recycling, first check the pressure difference and temperature, and then consider the performance degradation of the membrane core. Do not replace the membrane immediately.