Evaluation of mechanical face seals operating with hydrocarbon mixtures

Methods are introduced for calculating thermophysical properties of the common volatile media, such as hydrocarbon mixtures in a petrochemical plant. Using a suitable equation of state for simulating thermodynamic equilibrium of the media and taking parallel face seals as geometrical models, a computer program for predicting seal performance of various phase states mechanical face seals (MFS) operating with the mixtures is presented. Based on theoretical analysis and experimental results, a criterion named fluid film pressure coefficient Km for identifying phase states and phase states stability of MFS is put forward. An appropriate model for determining mean face temperature is set up and compared to the test results. It is shown that the predicted results are in excellent agreement with the test results. It is proved that the methods and program may be useful in practice. It is concluded that performance of MFS can be predicted only if thermophysical properties of a sealed medium could be expressed in suitable expressions.