IMPROVEMENT OF AMMONIA REFRIGERATION UNIT FOR STYRENE PRODUCTION

This article examines the purpose of ammonia refrigeration units (ARU), defining their importance and illustrating their role in various industries, particularly oil refining and petrochemicals. It also presents the current status of these units and outlines areas for improvement, primarily related to increasing their reliability and operational efficiency. The cooling cycle of an ammonia refrigeration unit used to cool antifreeze to negative temperatures in styrene production by dehydrogenating ethylbenzene on an iron-containing catalyst at Gazprom Neftekhim Salavat LLC has been calculated in the Unisim Design software environment. A cycle diagram in Ts coordinates is constructed and the dependences of the ammonia vapor consumption at the installation and the power consumption of the M-905 compressor on the proportion of distillation after the T-907 condenser are obtained, because of which the operation of the installation is analyzed. It was found that an increase in the proportion of distillation leads to an increase in the consumption of uncondensed ammonia and an increase in the power consumed by the compressor. Considering various solutions to this problem, it was revealed that the most rational is to install an additional heat exchanger (T-908) on the circulating water line of the T-907 condenser. This solution will increase the efficiency of ammonia vapor condensation and reduce compressor power consumption. A simulation of an ammonia refrigeration unit was performed in the Unisim Design software environment. The adequacy of the compiled model has been established by comparing the values of the main technological parameters of the installation operation obtained from the model with their actual values and norms of the technological regime. Using the obtained model, the thermal load of the additional T-908 heat exchanger (Q = 1.640 GJ/h) and the flow rate of the stored water into it (31.71 m3/h) were determined. Based on the data obtained, the technological calculation of the installed heat exchanger was performed: the approximate heat exchange surface area is 53.5 m2. According to the regulatory document TU 3612-023-00220302-01, a heat exchanger with U-shaped pipes with a heat exchange surface area of 61.6 m2 has been selected. The margin on the surface of the selected heat exchanger is 15 %, which is acceptable. The results of the calculation of the main technical and economic indicators of the effectiveness of the investment project to improve the ammonia refrigeration unit demonstrated the economic feasibility of the proposed technological solution.