Steam turbine - sudden temperature change

[Drexl]

Hi,
I'm looking at having two boilers connected in parallel that are delivering steam at different temperatures. If one of the boilers trip, I get a sudden drop in mass flow and a sudden change in temperature of the live steam. Would any turbine specialist be so kind to give some guiding values to how big a temperature change the turbine could handle?

Drex

 

[dougarthur42]

I am definitely not an expert on turbines but I have experience. We operate a turbine with 3 boilers in parallel. 2 of them operate at 400kpph of flow @950* f while the other operates at 600kpph of flow @865*f. Our normal turbine inlet temps is around 905 to 915*f. However if the bigger unit goes off line our inlet temps increase to about 945*f. If one or both of the smaller units go off line the inlet temp can drop to about 850*f. This is only about a 100*f differential but our unit handles it well. We may get a turbine expansion alarm but not a danger alarm and we just continue to operate as normal.

On another note when we are starting up we have some temperature limits, once our inlet flange metal temps reach about 680* we can increase rapidly. Before this temp we have temperature ramp rate that cannot be exceeded.
Hope it helps
Doug