ge reverse flow startingand loading

[blanjp]

We have retrofitted 2 300 mw ge turbines to reverse flow turbines with a bypass system, and only got the old SALI charts for a foward flow turbine fron GE, IE:The predicted steam block calculates steam temp after the stop valve bypass and nozzle blocks wereas we roll on the intercepts,Does anyone have something more current?

 

[byrdj]

If you are refering to the "predict block #5" (MST/MSP verses 1st stage steam temp, That block is derivered by the throttling calculculation (constaint h I believe) from before stop valve to the no load pressure at the 1st nozzle. the purpose is to ensure the steam applied during roll and low load hold does not greatly exceed temperature of the turbine rotor.

I don't Know what a reverse flow design is, but if you are rolling with hot reheat pressure, I have to believe another valve other than the IVs are controlling steam flow. the steam conditions (temperature)being applied to the RH rotor will need to be controlled to also limit the amount of mismatch temperture

 

[turboco1]

Back in the day, I started up GE's first European Bypass design turbine outside of Europe (Itabo II in the Dom. Rep.)

It had a Sulzer 100% Bypass system composed of HP and LP bypass valves and 100% flow capacity compact coolers for both main and reheat steam. The unit could take a full load rejection and the when the unit rpm returned to synchronous the Intercept on one side would begin to open to control and maintain synchronous speed...when the generator reconnected the station was in island mode (no external system load) the emergency diesel would stop... all in about 15 minutes as I recall. The Intercept valve was the controlling valve.

Also, when GE closed its Lynn Mass facility, they had let go all the controls test personnel. The last MkIII system to ship (for Talkha, Egypt combined cycle station) was not tested and I was asked to do testing on these last two systems. I was surprised when I got there and saw that the control valve circuit had 3 separate ramp curves and that there was only one control valves for each turbine AND that the control valve was a intercept valve from a cancelled order sitting on the shelf. If it can be done, they'll usually do it before losing money. The Intercept valve size and flow characteristics required the special control ramps to make linear steam flow for the 100mw steam turbine in a combined cycle configuration with sliding pressure control.

ps: Have not seen a reverse flow turbine...have seen reversing stages for marine applications though...???

 

[byrdj]

Turboco1,
I found ger4201 on line that implies that the unit is rolled with IP steam and steam is reversed through the HP to keep it cool.

Back in MY days, I had to go to Salam to factory test the last Schenectady MIIA

 

[turboco1]

I've seen SALI's where warming steam is admitted to the HP section and bottled for heating and I'm familiar with overheating of LP blades from windage and no steam flow for cooling, but HP blades should have no problem with these temperatures. IP section IV's usually have a internal bypass cooling hole in the disk for cooling the reheat section on load rejections. Also, on a load rejection the unit is above FSNL speed and I cannot imagine how any admitted steam at FSNL or higher could be flowed in reverse through stationary and rotating elements impulsing or reacting the steam in the opposite direction.

 

[turboco1]

I am thinking that this "reverse" flow turbine is an opposed flow or double flow section now whereas before it was a single flow section, stated as a "forward" flow.