(36a) Leading Edge Technologies of Large Power Mechanical Drive Steam Turbinefor 3.0 Mmta Ethylene Plants

According to the trend of ethylene cracker plant capacity increases from 1.0 MMTA to future 3.0 MMTA the required process flow for compressors and required power for steam turbine drivers substantially increase. Mitsubishi Heavy Industries Compressor Corporation (MCO) has lead the development and implementation of rotating equipment for the ethylene industry for several decades by providing state of the art designs with key safety features, high performance, and high reliability to end users on a global basis based on vast experiences.

MCO has finished the basic design of a 140MW class mechanical drive steam turbine for future 3.0 MMTA capacity which is based on with our experienced and proven components from site operating experience of 100MW class steam turbine. This paper serves as an introduction to this large power variable speed steam turbine and presents the main design features and key manufacturing points for such a large power range. The authors present ethylene plant trends, technology development history maps for design advancements, challenging technologies, verification tests, application results in terms of transient fluid dynamics, thermodynamics, rotor dynamics, and blade vibration strength evaluation.

In addition, after commissioning turbomachinery the performance and reliability tends to deteriorate during long-term operation. The typical damage and deterioration map for machinery is introduced and the authors explain practical technologies used to provide more efficient and reliable machines. This includes such topics as flow path surface treatment, effective on-line washing, anti-corrosion & erosion prevention, stage performance enhancement, and casing replacement technique that’s utilized for increasing capacity.