Shortening Start-Up Time and Life Prediction of Critical Components

steamturbine
Steam Turbine

This month we’re hosting the third segment to our Steam Turbine Webinar Series.

Shortening Start-Up Time and Life Prediction of Critical Components

Shortening  turbine start-up is a main concern for power machinery operators and manufacturers – is it a concern of yours?

A turbine unit’s integrity strongly depends on how it is operated. Turbine operating conditions are complex, mainly in terms of unsteady thermal and mechanical loading.  The most highly loaded period is during turbine start-up and shut down. During this period, an incorrect start-up of the turbine may lead to the significant shortening of a turbine’s lifetime or worse, unit failure. Therefore, the development of a turbine start-up is a very important part to the turbine unit design process.

And now a little education on turbine start-up and shut-down:

Power station output and generation need to be regulated constantly to match consumer demands. Economically, there is demand for the base load to be pro­vided by the most efficient plant, which mainly includes nuclear and large-capacity coalfield-sited coal-fired sta­tions.

More expensive (or less efficient) generating plants (small-capacity coal and oil-burning stations) are therefore needed to vary the output to match the demand. The plant that is required to run intermittently is known as a two-shift regime because of the requirement to run during two daytime shifts and to shut down during the night shift. But this plant may also be called upon to shut down over the weekend.

It’s now common for 500 MW and 660 MW machines to carry out two-shifting operations in addition to load-following cycles. This requirement for improved flexibility has resulted in all 500 MW and 660 MW turbine-generator units on the UK system to be designed to handle a two-shifting regime, in addition to the requirement for high effi­ciency base-load operation during early life.

These are some typical operational requirements for modern high merit tur­bine plants:

  • Hot Starts (Two-shifting) – Approximately 6 hours of shutdown with run up to full load in 30 minutes
  • Warm Starts – 24-72 hours shutdown
  • Cold Starts – Starts following > 120 hours prolonged shutdown
  • Load-following – Changes of load in 50 – 100% load range. Assuming a minimum of 3 hours between cycles

In our upcoming webinar we’ll discuss this and the basic principles of turbine start-up development by covering the advantages and problems to shortening start-up times and its influence on a units’ lifetime, in terms of turbine critical components fatigue.

Will you join us? You can read more or register for the webinar by clicking here.

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