Simulation And Development Of Internals For Gasoline Fractionator

As one of the essential petrochemical units, Ethylene unit has a long flow sheetand complex equipments. Gasoline fractionator is the key column and generally thebottleneck in revamp of this unit. Therefore, the performance of internals applied inthis column has significant influence on the unit capacity, product quality and energyconsumption.The present operating conditions and existing problems of gasoline fractionatorin Daqing Petrochemical Plant were analysized in this paper. It is shown that theoriginal simulation and present operating conditions are incorresponding. The currentcapacity is lower, and there is a high trend of coking. According to the characteristicsof process and equipment, the simulation method with PRO/II software provided bySimsci Company was discussed;the simulation results show that the abovementioned problems can be solved by application of new types of internals.In order to develop new types of internals, TH random packing and high adaptivevalve tray are proposed in this paper. The hydrodynamic and mass transfercharacteristics of Ф38 TH Rings had been systematically studied and compared withthose of Ф38 Pall Rings and Ф38 IMTP Packing. Experiments were carried out in acolumn of 600 mm diameter with air-oxygen-water system at atmospheric pressureand the packed bed height was 1000 mm. The gas pressure drop, flooding velocityand Height of a Transfer Unit (HTU) were measured. Results show that TH randompacking has much lower pressure-drop, larger capacity and higher mass transferefficiency than Pall Rings and IMTP. Meanwhile, by fitting the experimental data,semi-empirical equations of pressure drop, flooding gas velocity, liquid holdup andHTU were obtained.A fluid flow model, a flooding velocity model and a minimum liquid loadingmodel have been developed for the description of fully developed two-phasecountercurrent flow in randomly packed columns. These models have sound physicalfoundations and appear to be superior to earlier ones for they can predictpressure-drop above and below velocity of the loading or flooding more precisely.The hydrodynamics and mass transfer performance of HAVTH tray, F1 valvetrays and ADV tray are experimentally studied with air-water-oxygen system in a φ600mm stainless steel column. The results show that HAVTH tray possesses bettercharacteristics than F1 tray on hydrodynamics and mass transfer. Meanwhile,correlations of pressure-drop, weeping, entertainment and liquid height on tray wereobtained by processing experimental data, which can be applied in project designwithin the range of experiments.Mass transfer efficiency of valve tray is the key factor for the separation ofproduct. The the effect factors such as weeping, entertainment and fluid mixing onmass transfer efficiency are discussed, and the experimental equations are obtainedwhich can guide design and development of tray.Two new high performance internals were developed in this paper, which canincrease processing capacity, improve product quality and decrease energyconsumption significantly, and would bring great economic benefits.