| In this paper,Aspen plus simulation system is used to study and optimize the problems existing in the daily operation of a gas fractionation unit in Qingdao Anbang Refining and Chemical Co.,Ltd.and to explore the energy saving and consumption reducing measures in the actual production of the unit.Through Aspen plus simulation system,the three distillation columns of the unit are optimized one by one,and the optimized parameters are obtained,so that the gas fractionation can be dealt with in time.On the premise of guaranteeing the quality of the gas separation unit,the influence of operation parameters of each tower on the production and energy consumption of the unit is found out.According to the factories' actual data,a suitable thermodynamic method is selected,and the steady-state process model of gas separation unit is established by using the chemical process simulation software Aspenplus.By comparing the simulation data with the actual data,it is found that the error is less than 5%.Therefore,the simulation process established in this paper is reasonable and can provide guidance and optimization suggestions for the actual plant operation.The software sensitivity analysis module was used to analyze the relationship between the feed position of three towers and the load of reboiler at the bottom and condenser at the top of the tower.The optimum feed position of each tower was obtained.The feed plate of the de-propane tower was optimized from the 31 st plate to the 26 th plate,the feed position of the de-ethane tower was optimized from the 11 th plate to the 9th plate,and the feed position of the propylene tower was optimized from the 130 th plate to the 140 th plate.The relationship between the top pressure and the load of the top condenser and bottom reboiler of the de-propane tower was analyzed.The optimization suggestions were put forward: the top pressure of the de-propane tower was optimized to 1.6 MPa,the pressure of the de-ethane tower was optimized to 2.35 MPa,and the pressure of the refined propylene tower was optimized to 1.65 MPa.By analyzing the energy consumption of heat exchanger network in conventional five-tower process of gas fractionation,when the narrow point temperature difference ?Tmin = 6?,the narrow point is located at the temperature of hot logistics 46? and cold logistics 40?.Without adding new equipment,the heat transfer across the narrow point is eliminated,and the transformation and optimization of the existing heat exchanger network is completed.Through optimization,712.29 kW of load consumption and 712.29 kW of cold load consumption can be saved,and the additional energy input can be reduced.Through three energy-saving technological renovation projects,the heat exchange process of gas separation unit was optimized,and the steam consumption of each tower was reduced.The hot water heat exchanger at the bottom of propylene tower,the preheater of de-propane tower,the heat combined de-propane tower and the bottom reboiler of de-ethane tower were set up.The consumption of low-pressure steam was greatly reduced,and the steam consumption was reduced from 8.9 t/h to 6.3 t/h,with a decrease of 29.2%.It can save 20,800 tons of low-pressure steam every year.By using MINTAB statistical analysis tool,the optimum process parameters for propylene tower operation are put forward.The processing quantity is controlled at 8.0t/h~9.30t/h,the bottom temperature of crude propylene tower is controlled at 55.25 ~55.5?,and the top temperature of refined propylene tower is controlled at 43.30~43.5?.After the implementation of this optimization scheme,the company is expected to increase its benefits by 345..2 thousand yuan annually.After applying the optimized parameters to the actual production operation,the towers run smoothly and the product quality meets the requirements,which provides a theoretical basis for the operation management,fault analysis and operation optimization of the plant. |
PDF Full Text Request