Fresh air firing

[heatcycle]

I would liketo know if there is any example of Boiler which can manage to continue steam production - without any interruption-in Co-generation plant in case if Gas Turbine of GE- 9E capacity trips? In the configuraiton I am studying for, there is one GT and one ST.Apart from producing electricity it is vey important for the plant to produce steam continously. Boiler will run with supplementary firing in normal conditions and in case of GT trip, the boiler should be capable of producing steam with fresh air.
Is there such example of plant around the world ?

 

[shabushi]

Hi,
you can contact Deltek or Foster Wheeler. Since the 9E has 385-407 kg/s mass flow in the HRSG, if it trips, you will need a very large draft fan to do the work from a bye-pass system, that may not be economical. Unless you need large amount of steam from the HRSG if otherwise, the steam for GTCC is not worth.

 

[hrsgguru]

There are many examples of fresh air fired HRSGs that allow for continuous steam generation at or near normal combined cycle levels. However, I'm not aware of a system larger than a LM2500 in which this has been done in a non-interruptible approach.

For a unit the size of a GE Frame 9E, consider the challenge: rapidly replace 400 kg/s of 540°C exhaust heat via a duct burner supplied with ambient air. You'll need several thousand kW to drive the blower(s) and a greatly increased duct burner capacity to continue the same steam production.

A better approach would be to find out what bare minimum steam flow amounts are required for the plant to limp along and size the fresh air system and duct burner accordingly.

Keep in mind, too, that your emissions will likely increase when fresh air firing on a ppm basis.

 

[chicopee]

Co gen utility power plant in Ludlow,Mass has several gas fired turbines connected to generators; flue gas from turbines redirected to saturated W.T. boiler which in turns is connected to a saturated steam turbine. Very efficient plant which in the 1980's sold electricity at around 61/2 cents per KW in comparison to conventional power plant selling at about 12cents per KW.
Redundency is the key to your situation and should think about a smaller standby gas fired turbine.