Predicting the operating point of a centrifugal turbocharger to improve the anti-surge control algorithm within a process control system based on mathematical modeling

High-capacity centrifugal compressors of high and medium pressures are used in gas transmission systems of PJSC “GAZPROM,” at metallurgical plants, and at enterprises of the oil, chemical, and other industries. One of the factors affecting the reliability of technological processes is the prediction of surge to prevent accidents in centrifugal compressors. A review of the scientific literature reveals a lack of a unified algorithm for predicting surge. The present study focuses on the development of a simulation model of a turbocharger unit to supply blast air to a blast furnace with the required technological parameters. A description of the developed simulation model is presented using the example of the K-5500-41-1M centrifugal turbocharger with a K-22-90-2M steam turbine. The simulation model considers the operating modes of the turbocharger taking into account the thermodynamic parameters of the air from –35 оС to +35 оС based on actual and predicted characteristics of the turbocharger, considering its technical condition. The simulation model has been developed based on the thermohydraulic code (HS), which is a module of the SimInTech dynamic modeling environment. The authors have presented the results of computational modeling of the turbocharger that consists of a turbine, compressor, cooling system, and kinematic connection between the steam turbine and the compressor rotor. A dynamic visualization of the position of the compressor operating point on the gas-dynamic characteristic has been developed to monitor and determine the safe operation of the compressor (surge zone control). Methods to regulate the rotor speed by changing the steam turbine control mechanism (regulating steam valve) are described. Also, changes in the network characteristic due to the position of the air relief valve (ARV) are considered to change the blast parameters at the compressor discharge. The developed simulation model can be used to analyze and model operating modes of turbocharger units. The developed model allows creating and configuring the operating modes of centrifugal compressors at industrial enterprises. The developed model provides the possibility to visualizing the operating point, determining the permissible operation area, accounting for surge margin, evaluating the influence of ambient air parameters, and creating a new process control system algorithm for the turbocharger based on it.