Proposal of modernisation of a steam turbine stage before extraction, CFD and CSD analysis

The paper presents an idea and analysis of application of a new solution of a stage before extraction in the modernised LP part of 200MW turbines with ND exhaust. The idea of the patent is to introduce to the turbine steam path a ring directing high energy tip leakage steam from the stage to the regenerative extraction. Owing to this it is possible to cheaply achieve some energy benefits from the operation of first heat exchanger which in the modernised 200MW turbine is continuously underheated. Ring design has been checked using CFD and CSD numerical codes.