Abstract: A combustion control device including a bleed valve control unit for controlling a bleed valve disposed on a bleed pipe for performing bleeding so that a part of the compressed air flowing into the casing is not used as combustion air in the combustor, a fuel control unit for controlling a fuel regulating valve for regulating a fuel flow rate of fuel supplied to the combustor, and a temperature acquisition unit. Upon reception of a load rejection signal for cutting off a load from the gas turbine, the bleed valve control unit controls a valve opening degree of the bleed valve from a closed state to an open state with a prescribed opening degree, and the fuel control unit controls the fuel regulating valve such that the acquired flame temperature falls within a predetermined temperature range defined by an upper limit value and a lower limit value.

Abstract: The object of the present invention is to offer a heat transfer tube having a grooved inner surface, wherein the side edges of the board material do not form a waved shape and cracks do not form during tube expansion. In order to achieve this object, the grooved-inner-surface heat transfer tube of the present invention has a metallic tube with an inner circumferential surface, on which are formed a weld portion which extends in an axial direction of this metallic tube, a pair of projecting strip portions formed parallel to and separate from this weld portion, and a plurality of fins formed in an area between these projecting strip portions. The fins are formed with a constant angle with respect to the tube axis, and the ends of these fins are connected with the projecting strip portions. The thickness of the metallic tube within the grooves formed between the fins is made to increase in approaching the weld portion within an area surrounding the weld portion wherein the central angle is within 30.degree..