Flexibilization of power plants

 

Motivation

Heat transfer at the blade foot

The growing share of renewable energies leads to increasing grid fluctuations in the electricity supply, which have to be compensated currently by conventional power plants. This is accompanied by a simultaneous decrease in the annual full load hours of the conventional power stations. Hence, new operating solutions are necessary which increase the flexibility of the existing power plants in order to meet these requirements. For the execution of the energy transition from conventional to renewable energies, the power plants have to be as flexible as possible with simultaneous minimal lifetime consumption. One possibility is the accelerated power plant start-up using hot gas for keeping the steam turbine warm during a standstill (e.g. at the weekend). Thus, after the standstill a hot start can be realized instead of a cold start, which saves time, emissions, money and lifetime.

 

Methods

The institute currently investigates the heat transfer and flow phenomena during pre-heating respectively warm-keeping operation of a HP or IP steam turbines with hot air. During the warming process, the steam turbine is continuously rotated using a turning motor. The objective of the investigations is the steady-state warming operation over a longer period of time, which makes it possible to start the turbine at any time very quickly. This operation is investigated using a numerical Conjugate Heat Transfer (CHT) model, from which analytical calculation methods are derived, which allow for a quick and simplified calculation of the temperature distribution in the critical components. Based on this, the efficiency of the pre-heating / warm-keeping operation can be evaluated.