Hello,

We found that surprisingly the steam setpoint is set at 540degC unless IGVs do not get over 77 degrees. Is there any known reason why steam setpoint cannot go straight, once machine above minimum turndown, to its nominal setpoint? In this case 565C. Is it like a sort of initial warmup?

Can CSA comment on this?

This makes user to go above 77degress in IGVs and then ramp down to the desired load which of course is not convenient for the market.
This is a single shaft 9FA, 400 Mw single shaft.

Thanks.
Regards.

 

You have a steam temp setpoint of 540C and IGV's are at 77?? Sounds like you are not in temperature matching.

The steam setpoint is normally provided by the plant DCS/BOP. This typically looks at the inlet bowl temperature with a small positive delta and slowly increases as the steam turbine warms up.

The temperature is first controlled by lowering the GT to minimum and then closing the IGV towards minimum. If the IGVs are at minimum and higher temperature is required only then will the GT load start to increase. Once temperature matching has finished the GT must be return to minimum load/minimum igv before load raise/preselect/cable_remote/agc can be enabled. You can not control turbine load during turbine matching. The MK6 will do what it needs to achieve the required exhaust/steam temperature.

Out steam temperature matching range is from 290c with a ST release at 410c.