Reference: Power Upgrade with new Inner Casing
Steam turbine availability is of crucial importance, especially in ethylene refineries. Based on positive experiences with Siemens, the customer decided to pursue a revamp because they trust the Siemens OEM solution. The customer, one of the largest ethylene plants in Asia, was built in the 21st century and aimed for a power upgrade in order to operate the driven compressor with a higher gas mass flow. Since the higher speed /power output can cover the degradation of the compressor, the customer was also interested in an availability increase for their SST-600 steam turbine.
The modernization was successfully executed in 2019 within the scheduled time frame. With the goal of increasing the power output while keeping the compressor's speed the same, a new inner casing with an additional nozzle segment and an integrated guide blade carrier to accommodate the higher live steam flow was implemented. The inner casing was optimized for the new operating conditions and manufactured to fit in the existing outer casing. In addition, the spare rotor of the turbine was modified.
Once the project was completed, the performance of the turbine was improved with an increase in power output of 5% and more availability.
The execution on-site lasted approx. 6 weeks, whereby Major Overhauls of a compressor and two additional trains had to be carried out as well.