i need to know the diameter exactly inmeters . I like to know how big most be the boiler to produce enough presure to make working 25 MW electricity ???
A steam generator to produce sufficient steam to drive a 25 MW generator would not be a round one but rather a water tube boiler with one steam drum and one or more likely two mud drums. The pressure required to drive the steam turbine can be anywhere from a few hundred pounds pressure to a 1000 pounds pressure. You have to have pressure but you also have to have a large quantity of steam. That more than anything sets the size of the boiler. The bottom line is simply that there are too many variables to provide just one answer to your question.
