Waste heat utilization system capable of improving combined cycle economical efficiency of gas turbine

Abstract

The invention provides a waste heat utilization system capable of improving the combined cycle economical efficiency of a gas turbine. The system comprises a vertical pipe type air preheater used forimproving temperature of inlet air and a main flue arranged between a waste heat boiler and the vertical pipe type air preheater. The main flue comprises a gas inlet flue and an exhaust flue. The gasinlet flue is arranged between an inlet flue on the flue gas side of a low-temperature coal economizer of the waste heat boiler and an inlet of the vertical pipe type air preheater, and flue gas wasteheat of the waste heat boiler is transmitted to the vertical pipe type air preheater. The exhaust flue is arranged between an outlet of the vertical pipe type air preheater and an outlet flue on theflue gas side of the low-temperature coal economizer of the waste heat boiler so as to transmit flue gas generated after heat exchange of the vertical pipe type air preheater to the waste heat boiler.The inlet air of a compressor is heated through part of low-grade flue gas drawn out from the flue gas side of the low-temperature coal economizer of the waste heat boiler, waste heat gradient utilization is achieved, the flue gas exhaust temperature of the waste heat boiler can be further reduced, the efficiency of the waste heat boiler is improved, and the operation economical efficiency of a combined cycle unit is improved.

Description

technical field [0001] The invention relates to performance optimization of a gas turbine combined cycle unit, in particular to a system for improving the operating economy of a gas turbine combined cycle unit by adopting flue gas waste heat utilization technology. Background technique [0002] The gas turbine combined cycle unit can not only be used as a peaking unit but also has the ability to drive the base load, especially for the gas turbine combined heat and power unit, its operation mode is "heat-based power generation", and the power generation load is relatively stable compared with the peaking unit. However, with the continuous increase of the installed capacity of electric generators, it is difficult for gas-fired units to maintain operation under rated load. Under partial load, due to their high heat consumption rate, the unit’s operating economy is poor, especially in the current peak-shaving auxiliary services. Under the policy background, gas-fired power plant...

AI Technical Summary

Problems solved by technology

[0005] (1) When the ambient temperature is low in winter and the gas turbine is running, if the water volume is not enough to adjust the temperature behind the air intake heater by adjusting the water volume; or when the water intake of the air intake heater is cut off, the air intake heater The water in the air intake heater will freeze and crack, causing the heater tube to be damaged

Further pipe damage may allow water to be carried into the compressor, which will jeopardize the safe operation of the gas turbine

[0006] (2) For the gas turbine combined cycle unit that has been put into operation, the exhaust gas temperature of the waste heat boiler is affected by factors such as the scaling of the heat exchanger tube wall, which makes the exhaust gas temperature rise and the heat transfer performance of the waste heat boiler decreases

The existing technology does not propose an effective method to further reduce the exhaust gas temperature, so that the economic improvement effect of the combined cycle unit is not obvious

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