A Waste Heat Utilization System for Improving the Economy of Gas Turbine Combined Cycle

Abstract

The invention provides a waste heat utilization system for improving the economy of gas turbine combined cycle, which includes a vertical tubular air preheater to increase the temperature of the inlet air; and a waste heat boiler and the vertical tubular air preheater The main flue between the air preheaters, the main flue includes an intake flue and an exhaust flue, and the intake flue is set at the inlet of the low-temperature economizer flue gas side of the waste heat boiler Between the flue and the inlet of the vertical tubular air preheater, the waste heat of the flue gas from the waste heat boiler is transferred to the vertical tubular air preheater, and the exhaust flue is arranged at the vertical Between the outlet of the tubular air preheater and the outlet flue of the flue gas side of the low temperature economizer of the waste heat boiler, the flue gas after heat exchange of the vertical tubular air preheater is sent to the waste heat boiler. The present invention uses part of the low-grade flue gas extracted from the inlet flue gas side of the low-temperature economizer of the waste heat boiler to heat the inlet air of the compressor, realizes cascaded utilization of waste heat, can further reduce the exhaust gas temperature of the waste heat boiler, improve the efficiency of the waste heat boiler, and improve Operating economics of combined cycle units.

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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