Abstract: The problem of high energy consumption and load mismatch occurred in the cracking gas compressor unit after the "1.1 million tons reconstruction and expansion" of the ethylene plant in one company. Aiming at these problems, the internal efficiency and energy consumption of the cracking gas turbine were calculated by real-time operation parameters and compared with the standard parameters provided by the manufacturer. The work done by the compressor was calculated by ASPEN PLUS simulation, and then the mechanical efficiency of the unit was obtained. The flow area of the steam turbine and the real-time working condition of the condenser were analyzed by adopting the "Freugel formula" and the fitted standard curve of condenser. The results show that the flow area of the high pressure part of the turbine decreases and the internal efficiency decreases, which leads to the deviating of the real-time working condition of the condenser from the characteristic curve, resulting in high energy consumption of the unit.

Key words: ethylene plant, cracking gas compressor unit, internal efficiency, energy consumption