Good day!

We have two siemens steam turbines with gross generation of 60 MW each and facing same problem on both machines.

When machine trips then its temperature at inlet of extraction control valve rises above 250 °C which makes machine unavailable to start for more than three hours until unless this temperature comes below 250 °C. This temperature remains below 250 °C after normal shutdown and decreases further rapidly.


Why this temperature increases above the safe value after tripping?
Why it takes too long to come down after tripping?

 

If possible, modify the turbine trip procedure to allow a brief period of controlled blowdown (steam release) from the turbine. This can help evacuate residual steam and heat, speeding up the cooling of the system.