The Influence Of Parameters Fluctuation On The System Of Hydrocarbon Recovery Process By Membrane Technology

With the development of modern industry, nonrenewable resources such as oil and natural gas are consumed significantly. The recovery of high value-added light hydrocarbons from oil-associated gas is becomes increasingly necessary and important. The recovery of light hydrocarbons is an important process in the comprehensive utilization of oil and gas. It is important for relieving the pressure caused by energy crisis and improving the resource utilization rate. In actual production, the recovery process of light hydrocarbons is often interfered by many disturbances from the outside of system, such as the fluctuation of raw materials flow and composition, which have bad effect on the quality of the products and can do great damage to equipment. So it is necessary to monitor important parameters of production process with time by dynamic simulation technology. The variations of all parameters are reflected accurately in time. The effect of the fluctuation of parameters on the system was analyzed. The operations and parameters adopted when working condition changed are studied, so devices can be optimized rapidly. The consumption of resources and energy are reduced. The results can provide guidance for the choose of operation condition. The recovery process of light hydrocarbons from oil-associated gas is investigated and simulated by UniSim Design simulation software in the paper.On account of the recovery of light hydrocarbons from a large oil field, shallow cooling hydrocarbons recovery process and membrane-expender hybrid technology were simulated steadily and optimized with UniSim Design software. The results showed that-30℃was chosen as condensation temperature in shallow cooling hydrocarbons recovery process. With the operating conditions above, a profit of35.25million yuan/a, the light hydrocarbons mass of1854.4t/a, a recovery rate of37.4%were obtained. The composition of light hydrocarbons in vent gas was6.91mol%. The condensation temperature of-33℃, the permeate pressure of145kPa, the membrane of40m2were chosen as the operating conditions in the membrane-expender hybrid process. With these conditions above, a profit of40.93million yuan/a, the light hydrocarbons mass of3738t/a, a recovery rate of78.4%were obtained. The composition of light hydrocarbons in vent gas was reduced from6.91mol%to2.37mol%. Compared with shallow cooling hydrocarbons recovery process, the profit of membrane-expender hybrid process was increased5.68million yuan/a; the recovery rate was increased by41%. It was concluded that the profit of membrane hybrid process was more. The recovery of light hydrocarbons was increased and the waste of resources was reduced.Based on the structure of steady simulation, some operating model including membrane separation, LNG, distillation column, pipeline, valve and so on were set up reasonably in dynamic model in the paper. The control system was designed. Then the steady simulation was converted to dynamic simulation based on the initial valve in steady simulation. After dynamic model ran steadily, the values of some parameters, such as the flow rate of oil-associated gas, the composition of propane in the gas and membrane area were changed. The effects on the system were studied. The results showed that all variables monitored fluctuated in at the beginning of a period of time, then they showed a steady trend gradually with time. It could prove that the dynamic setting was reasonably and the system has the ability of anti-disturbance. The working stability and operability of membrane separation model were well and enhanced the stability and flexibility of entire process system.