The Measurement Of Physical Properties Related To PTA And Research Of Correlation Method Of Mixture Liquid Surface Tension

Pure terephthalic acid (PTA) is the main raw material in the manufacturing polyesters. The level of the technology in producing PTA influences the development of the polyester industry. It is necessary to obtain the basic physical and thermodynamics properties for 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 mearsured.Two correlation method of mixture liquid surface tension was obtained.The differential maximum bubble pressure method which is adopted in this experiment is the maximum bubble pressure method's transform. Using the method, a set of the equipment was built up, the binary mixture of xylene + acetic acid and the ternary mixture of p-xylene + acetic acid + water in whole densities'surface tension from 303.15K to 343.15K at atmosphere pressure were measured, these properties were calculated and correlation. The corrected equations were obtained for the binary system and the ternary mixture. It is useful and important for engineering and technology design. Meanwhile, using the Japanese Density/Specific Gravity Meter DA-505U vibration tube, the density of those systems were measured and the calculation to these data were carried on.Then comparing the maximum bubble pressure method with the differential maximum bubble pressure method, the binary mixture of p-xylene + acetic acid's surface tension data were obtained, the results indicated that the differential maximum bubble pressure method and the maximum bubble pressure method can obtain the credible results.Two modified surface tension models for the binary systems were obtained. Through the first model, the binary systems can be correlated including the composition and temperature at the same temperature.Through the second model, the binary systems can be correlated including the composition and temperature with different temperatures. There are 72 systems (112 temperatures and 1225 different concentrations) including polar and nonpolar systems, comparing the referred the calculation results showed that the modified models can be applied to the correlation. The results indicated that the polarity's effect is not big for the two models. Due to its better convenient, the second model is recommended to use. Meanwhile, the p-xylene + acetic acid + water ternary system was predicted, the result was satisfactory.