Abstract: The invention concerns a boiler comprising at least a first heat exchanger (10) with its inlet connected to a water supplying duct (18) and its outlet connected, through a first regulating valve (30) to a steam turbine, either directly, or through a second heat exchanger (12). During the starting phase the regulating valve (30) is closed and as long as the fluid at the first heat exchanger (10) outlet is a mixture of water and steam, all the water is transformed into steam by condensation and the regulating valve (30) is opened only when the fluid at the first evaporator outlet is pure steam.

Abstract: The invention relates to a boiler (1) wherein at least one steam generating circuit comprises an ejector (25) capable of providing induced circulation of water in the boiler in normal operating conditions. The corresponding water/steam separation reservoir (17) is arranged at any height with respect to the outlet collector (manifold) (15) of the evaporator device (11) of said circuit.