for 30MW power generation unit wich is better " single shaft or double shaft gas turbine"?

Question

please explane with reference

Answer 1

I suspect that the two shaft option is a legacy from the days when aero engine derivative gas generators were preferred on the basis of their tried and tested performance and cost (being that jet engines are produced in some numbers). So much in choosing important machinery is a question of confidence that one will get reliable performance. I don't myself believe that two shaft machine would ever have emerged for industrial use if it were not for that factor, due to extra complexity (more control systems, bearing and seal systems and more manufacturing in shafts). Once a trend has been established it may continue even after the reasons why it was established have disappeared, people sticking to what they are used to.

Edited comment: The link below contains reference to 125MW GE Frame 9E gas turbines (which I believe are single shaft) driving process compressors. Perhaps not directly relevant but interesting.

http://www.gepower.com/businesses/ge_oilandgas/en/applications/lng_prodplant.htm

Answer 2

In theory a single shaft ensures that the gas compression, power turbine and generator are all synchronous and that the generator frequency is very stable.

The reality is that modern governor and fuel controls are able to easily compensate for any potential differences between shaft speeds.

In my experience, the two shaft option is more maintainable and helps prevent undesired consequences from either the generator or turbine from being transferred to the other.

Vendors always argue this one, but more from trying to establish a competative advantage. I'm not aware of any independent studies or benchmarks here.

Answer 3

double shaft gas turbine