Fuel gas and steam combined cycle power generating method with multiple gas turbines and system

Abstract

The invention relates to a fuel gas and steam combined cycle power generating method with multiple gas turbines and a system; the fuel gas and steam combined cycle power generating system formed by the method comprises multiple gas turbines, gas compressors of part of the gas turbines are used for compressing the fuel gas, and the gas compressors of other gas turbines are used for compressing air. By adopting the method of the invention, the work for developing different new gas turbines and re-constructing the existing gas turbines for fuel with different heat values is reduced, so as to avoid the reduction of the efficiency, caused by the reconstruction of the gas turbines and reduce the efficiency reduction caused by mechanical transmission loss and electrical energy and mechanical energy conversion loss. The method and the system can be applied to the fuel gas and steam combined cycle power generating field.

Description

technical field [0001] The present invention relates to a method for power generation of gas and steam combined cycle and a system using the method, in particular to a method for using multiple gas turbines to generate gas and steam combined cycle and a system using the method. Background technique [0002] In the prior art, the gas-steam combined cycle power generation technology using a gas turbine is to first perform a top power cycle of the gas in the gas turbine, and then use the high-temperature flue gas at the outlet of the gas turbine to construct a bottom steam power cycle to form a gas-steam combined cycle. Since the high heat source of the top gas power cycle has a higher temperature, while the lower heat source of the bottom steam power cycle has a lower temperature, the gas and steam combined cycle has a higher cycle efficiency, and the net power generation efficiency of the cycle can exceed 55%. [0003] In the existing gas and steam combined cycle power genera...

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Problems solved by technology

Generally, the efficiency of the gas compressor is lower than that of the gas turbine compressor, and when the gas compressor is driven by the gas turbine coaxial or side shaft, there are mechanical transmission losses of the coupling mechanism and the reducer. Power conversion and mechanical transmission losses from the turbine shaft to the generator to the motor and compressor

[0007] Due to the above two problems, when low calorific value gas is used in gas and steam combined cycle power generation system, its efficiency is lower than that of high calorific value gas

For example, for natural gas, the thermoelectric conversion efficiency can reach 56%, while the heat value is 800×4.18kJ / m 3 of blast furnace gas, its thermoelectric conversion efficiency is lower than 46%

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