Process Simulation & Analysis For Industrially Uncatalysed Oxidation Of Cyclohexane

A model of five-bubble-stirred-tank reactor (BSTR) for industrial uncatalyzed oxidation process of cyclohexane was established to predict and optimize the the industrial production. In the model, the energy balance was considered for the process with no addition of feed cyclohexane to control reactor temperature.The process model was built on the Chen's kinetic equations of the uncatalyzed cyclohexane oxidation and the complete mixing pattern for gas and liquid two-phase flow in BSTR. The reaction rate constants in Chen's kinetic equations were revised according to the designed data (44000tIy cyclohexone) of the industrial equipment because of the difference between the material of the laboratorial equipment and that of the industrial equipment. Due to lack of reaction heat of cyclohexane oxidation, the formation heat of components in the oxidation reaction was used to estimate the reaction heat. The reliability of the model built was verified by the practical data of 120% production ability. The model established could well predict the temperature variation in reactors and the distribution of cyclohexane oxidation reaction system.The influence of the operating parameters such as cyclohexane flux, the amount of fresh air, operating temperature and oxygen content in the input air on the production index (the conversion, the selectivity and the yield) was analyzed on the model. The conversion and the yield increase with increasing amount of fresh air, or the operating temperature, or oxygen concentration in the input air and with reducing amount of cyclohexane flux. However, the selectivity decreases. Among these operating parameters, the cyclohexane flux, the amount of the fresh air and the oxygen content in the input air are remarkable factors. Uniform Design Method was applied to search for the suitable operating condition for the amount of the fresh air, the cyclohexane flux and the oxygen content in input air. It was found that the high ratio of the fresh air and the cyclohexane flux would increase the conversion and yield and reduce the selectivity. The oxygen content in the input air is better limited within 19-23% for higher selectivity (>90%) and higher conversion (<5%), and fresh air i~ reasonable reactant gas source. The multi-objective optimization was also conducted. The suitable temperature sequence and input air for reactors of cyclohexane oxidation was found, and the conversion and yield can be increased.