GAS TURBINE COGENERATION SYSTEM AND OPERATION MODE CHANGE METHOD THEREFOR

摘要

Reduction of operation efficiency of a GTCS at a time of changing an operation using bypass stack 30 to an operation using HRSG is suppressed. An HRSG of the GTCS is provided with an air supply piping P2 and a ventilation piping P3 connected to a fuel line of a duct burner 52 at a position upstream of a main shut-off valve V1 and downstream of a fuel shut-off valve V2, an air supply shut-off valve V3 that opens/closes the air supply piping P2, and a ventilation shut-off valve V4 that opens/closes the ventilation piping P3, and is configured such that during an operation using a bypass stack 30, an inlet of the HRSG is closed to open a bypass stack 30, a main shut-off valve V1 and the fuel shut-off valve V2 are closed, and the air supply shut-off valve V3 and the ventilation shut-off valve V4 are always opened, and at a time of changing to an operation using HRSG, the inlet of the HRSG is opened to close the bypass stack 30 without shutting down a GT, the main shut-off valve V1 and the fuel shut-off valve V2 are opened, and the air supply shut-off valve V3 and the ventilation shut-off valve V4 are closed.