Abstract: A noise reduction device includes: a first waveform acquisition unit configured to acquire, based on a reference signal that is obtained by detecting vibration at a first position of an exhaust duct of a gas turbine, a first waveform representing vibration of the exhaust duct; an unbalanced motor configured to apply, at a second position of the exhaust duct, vibration at a target frequency designated for the exhaust duct; a second waveform acquisition unit configured to acquire, based on a measurement signal obtained by measuring a rotation pulse of the unbalanced motor, a second waveform representing rotation of the unbalanced motor; a setting unit configured to set the target frequency based on the first waveform; and a correction unit configured to correct the target frequency, to achieve a predetermined phase difference between the first waveform and the second waveform.

Abstract: A heat exchange system includes: a gas line through which a gas to be cooled flows; a first heat exchanger disposed in the gas line and configured to cool the gas through heat exchange with a refrigerant; a refrigerant introduction line for introducing the refrigerant into the first heat exchanger; a refrigerant discharge line for discharging the refrigerant after cooling the gas from the first heat exchanger; a recirculation line for recirculating at least a part of the refrigerant flowing through the refrigerant discharge line into the refrigerant introduction line; and a flow-rate adjustment unit for adjusting a flow rate of the refrigerant flowing through the recirculation line so that a temperature of the refrigerant introduced into the first heat exchanger from the refrigerant introduction line is not lower than a threshold.

Abstract: A heat exchange system includes: a gas line through which a gas to be cooled flows; a first heat exchanger disposed in the gas line and configured to cool the gas through heat exchange with a refrigerant; a refrigerant introduction line for introducing the refrigerant into the first heat exchanger; a refrigerant discharge line for discharging the refrigerant after cooling the gas from the first heat exchanger; a recirculation line for recirculating at least a part of the refrigerant flowing through the refrigerant discharge line into the refrigerant introduction line; and a flow-rate adjustment unit for adjusting a flow rate of the refrigerant flowing through the recirculation line so that a temperature of the refrigerant introduced into the first heat exchanger from the refrigerant introduction line is not lower than a threshold.