The Measurement And Research Of Surface Tension Of Liquid Mixtures Related To Terephthalic Acid (PTA) At High Pressure

Pure terephthalic acid (PTA) is the main raw material in the manufacturing polyesters. It is necessary to obtain the basic physical and thermodynamics properties for home designing independently developing new process of PTA or renovating old equipment and process. The surface tension is an important parameter among them. Because of the technique monopoly, all these basic about PTA design is not announced in public. Hence, to the request of the China Petrochemical Corporation, the surface tension data of the related system in the PTA production process were measured. The data of surface tension was correlated by linear and polynomial equation.The differential maximum bubble pressure method which is adopted in this experiment is the maximum bubble pressure method's transform. It is used to measure surface tension not only at atmospheric pressure, but also at high pressure. This method using two differential diameter capillaries, calculates the surface tension with the differential pressure measured by the differential pressure transmitter. In this paper, adjust the differential high, and measure the radii of capillaries accurately, reduce the error of experiment.Comparing atmospheric pressure, it is more difficult to measure the physical properties at high pressure. The data are scarce in literature. In this paper, the differential pressure maximum bubble pressure equipment were designed and manufactured independently. The configuration of it is presented in detail. The airproofing, temperature control, airflow control, differential pressure and the collection and save of data were examined. Using the methanol and xylene, the pressure temperature and repetition of the equipment are checked. Using the method, the compounds of benzene, toluene, p, m, o-xylene and the binary mixture of p-xylene + ethanol, p-xylene +, p-xylene + acetic acid were measured firstly, from 353.15K to 473.15K, at 1.5MPa, in different concentration. First of all, the data were correlated by a function of temperature. Second, they are correlated by two methods including the composition and temperature. The new model was proved out by the 23 binary at atmospheric pressure. The measured data were calculated using it. Give all the relating ADD%. The measured compounds and systems were predicted by the method of corresponding state. Meanwhile, it was modified, and gained the new parameters. It is useful and important for engineering and technology design.