Solid oxide fuel cell system, combined power generation system including the same, and method for stopping solid oxide fuel cell system

摘要

PROBLEM TO BE SOLVED: To provide: a solid oxide fuel cell system which can surely prevent a fuel electrode from being broken; a composite power generation system including such a solid oxide fuel cell system; and a method for stopping the solid oxide fuel cell system.SOLUTION: In a method for stopping a solid oxide fuel cell system, when transmission or supply of a fuel gas and an oxidizing gas is stopped, the solid oxide fuel cell system transitions to Trip, whereby a first shut-off valve 61 and a second shut-off valve 63 are opened to lower the pressure of the fuel gas and the oxidizing gas in a solid oxide fuel cell 15. Immediately after the transmission or supply of the oxidizing gas is shut off, or when the pressure of the oxidizing gas in the solid oxide fuel cell 15 reaches a predetermined value, a third shut-off valve 77 is opened, and an inert gas or a purge gas consisting of any oxidizing gas other than oxygen is transmitted/supplied to an air electrode, lowering an oxygen partial pressure in the air electrode.SELECTED DRAWING: Figure 1