Patent ID: 8881690

Claim:
A steam generator comprising: a heat transfer tube group that is formed of a plurality of heat transfer tubes each having a U-shaped end opposite to ends that are secured to a tube plate, and each having a heat medium flow from one secured end toward another secured end; an annular channel that is formed so as to cover the circumference of the heat transfer tube group and that has an opening, at a lower portion thereof, that communicates with the heat transfer tube group; a water supply unit having a semi-ring shape that is disposed at an upper portion of the annular channel and that supplies water to a descending-side portion serving as an area where the heat medium in the heat transfer tubes descends toward the another secured end; and a steam/water separator that is disposed above the heat transfer tube group and that separates water heated while passing from the annular channel along the circumference of the heat transfer tubes into steam and hot water, wherein an air bubble removing member for removing air bubbles is provided in a rising-side portion that includes the annular channel, wherein the air bubble removing member is a water supply member having a semi-ring shape that is located on the rising-side portion to supply water to the rising-side portion for condensing the air bubbles, wherein the water supply member having the semi-ring shape is branched from the water supply unit to supply water in an amount that is sufficient to condense the air bubbles, and wherein a pipe diameter of the semi-ring shaped water supply member being smaller than a pipe diameter of the semi-ring shaped water supply unit.