JP3530243B2 - Regenerative gas turbine combined cycle power generation method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved regenerative gas turbine combined cycle power generation method having significantly improved power generation efficiency. More specifically, the thermal energy of the high-temperature and high-pressure combustion gas is effectively used, the temperature of the steam supplied to the steam turbine is increased, the thermal efficiency of both the gas turbine and the steam turbine is increased, and the resulting thermal energy is discarded. The present invention relates to an improved regenerative gas turbine combined cycle power generation method in which the power generation efficiency is significantly reduced as a whole and reduced. [0002] Main methods of converting energy from combustion into electric energy through a prime mover include a power generation method using a gas turbine and a power generation method using a steam turbine. When a gas turbine is used, the gas turbine is rotated by high-temperature and high-pressure gas obtained by the combustion of compressed air and fuel, and power is extracted from the rotating turbine shaft.
On the other hand, when a steam turbine is used, the turbine is rotated by high-temperature and high-pressure steam generated by a boiler, and power is extracted from the rotating turbine shaft. Comparing the thermal efficiencies of the two, the thermal efficiency of the gas turbine exceeds that of the steam turbine.
High-temperature exhaust heat of 0 to 600 ° C. is exhausted. Therefore, a gas turbine combined cycle power generation method combining both advantages has been developed and put into practical use. That is, 10
By operating multiple 10,000 kilowatt-class gas turbines for efficient power generation, and using the waste heat of the obtained exhaust gas to generate steam, generating power using the steam turbine, and recovering the thermal energy of the combustion gas twice. It is a method of generating electricity. Recently, as an improved type of power generation by a gas turbine, high-temperature exhaust gas after driving the gas turbine and compressed air supplied to a combustor of the gas turbine are heat-exchanged by a heat exchanger to heat the compressed air. Regeneration-type cycle power generation, which reduces the fuel of the gas turbine and consequently improves the thermal efficiency (power generation efficiency) of the gas turbine, has become known. Japanese Patent Application Laid-Open No. Hei 5-332164 discloses that in order to further improve the output of a gas turbine, the exhaust energy of the gas turbine is recovered to a low temperature level.
Techniques for providing a cooling means such as spraying water into compressed air have been proposed. Further, Japanese Patent Application Laid-Open No. 6-212909 discloses that in a combined power generation plant in which exhaust gas from a gas turbine is injected into a boiler as combustion air, air or fuel injected into a combustor of the gas turbine is heated by exhaust gas heat of the boiler. Technology has been proposed. [0004] Gas turbine combined cycle power generation has a higher thermal efficiency of 43 to 47% (HHV base, HHV: higher heating value) than conventional power generation methods, but is still satisfactory. Not something. In particular, in the current situation where the electrification rate, which indicates a shift of energy demand to electric power, is increasing year by year, improving power generation efficiency has also reduced power generation costs, reduced fossil fuel usage, and reduced air pollution due to combustion exhaust gas. A related and important issue. With the current situation in which energy not converted to electric power causes thermal wastewater, development of a power generation system capable of efficiently recovering electric power energy from combustion energy is eagerly desired. As described above, a regenerative gas turbine for increasing the thermal efficiency of the gas turbine itself is also known. However, it is required to further improve the thermal efficiency of the entire gas turbine combined cycle power generation system. The present invention has been made in view of the above technical level, and provides a regenerative gas turbine combined cycle power generation method capable of obtaining higher power generation efficiency than conventional power generation efficiency and reducing the amount of waste energy. The purpose is to: Means for Solving the Problems The present inventors have studied in detail a gas turbine combined cycle power generation system and a regenerative gas turbine power generation system in order to achieve the above object, and In a regenerative gas turbine combined power generation system combining a regenerative gas turbine and a steam turbine, a tubular steam superheater for increasing the thermal efficiency of the steam turbine system is disposed between the combustor and the gas turbine. Overheating the steam that is supplied to the system, together with the efficiency of the regenerative gas turbine, increases the power generation efficiency of the steam turbine, resulting in a reduction in the amount of waste energy and can dramatically improve the power generation efficiency of the entire system And completed the present invention. That is, the present invention includes a heat exchanger for driving a gas turbine with high-temperature and high-pressure combustion gas obtained by supplying compressed air and fuel to a combustor to generate electric power, and for converting combustion exhaust gas driving the gas turbine to a heat exchanger. In a regenerative gas turbine combined cycle power generation, which is a heat source for generating steam for heating compressed air supplied to the combustor of the gas turbine and generating power by the steam turbine, the combustor and gas A tubular steam superheater using the high-temperature and high-pressure combustion gas as a heat source is provided between the turbine and a steam generated by a waste heat recovery boiler to guide the superheated steam and supply the obtained superheated steam to the steam turbine. The present invention provides a regenerative gas turbine combined cycle power generation method. When the power generation by the regenerative gas turbine is applied to the gas turbine combined cycle power generation, the power generation efficiency of the gas turbine combined cycle power generation is improved, but the thermal efficiency of the steam turbine is reduced. However, according to the present invention, any of them can be improved, and the thermal efficiency of the entire system can be dramatically improved. Hereinafter, the power generation method of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of a power generation system of a regenerative gas turbine combined cycle power generation combining a tubular steam superheater according to the present invention. In FIG. 1, only the main equipment is shown, and the attached equipment is omitted. In FIG. 1, the air 1 taken in is compressed by an air compressor 2 to become compressed air 15, guided to a heater 11 of a waste heat boiler 10, and sent into a combustor 4 as heated compressed air 16. . The fuel 3 is supplied to the combustor 4. Natural gas is preferred as the fuel, but other hydrocarbon-containing fuels may be used if there is no quality problem such as heavy metal content. The high-temperature and high-pressure combustion gas 5 generated in the combustor 4 is approximately 1450 ° C., and is led to a tubular steam superheater 6. The tubular steam superheater 6 is a kind of heat exchanger. The low-temperature steam 12 is introduced into a number of small tubes arranged in the tubular steam superheater 6, and the high-temperature and high-pressure combustion gas 5 is introduced inside the superheater and outside the small tubes. Heat exchange between the high-pressure combustion gas 5 and the low-temperature steam 12;
High-temperature, high-pressure superheated steam 14 superheated from the capillary outlet
Is to take out. On the other hand, the combustion gas deprived of heat by heat exchange outside the narrow tube in the tubular steam superheater 6 is discharged as combustion gas 7 from the other end of the superheater.
The thin tube has a temperature of about 1450 ° C and a pressure of about 20 at
a, the low-temperature steam 12 introduced into the thin tube in the superheater is relatively low at about 300 to 400 ° C., and heat is exchanged on the surface of the thin tube. 5 can be overheated by heat exchange without causing breakage of the thin tube or the like. A feature of the present invention is that the combustor 4 and the gas turbine 9
And that the tubular steam superheater 6 is installed. Specifically, in the waste heat recovery boiler 10, heat exchange is performed between the low-temperature steam 12 having a temperature of about 300 to 400 ° C. generated by the steam heater 13 and the combustion gas 5 having a temperature of 1450 ° C. As a result, the combustion gas 7 at a temperature of about 1350 ° C. and the temperature of about 600 ° C.
Overheated steam 14 is discharged. The combustion gas 7 after the heat exchange has a pressure of 15 to 20 a.
ta high-pressure high-temperature energy, and the gas turbine 9
And the rotational power of the turbine shaft is used for power generation. In the power generation method of the present invention, since the configuration of the regenerative gas turbine system is adopted, the high-temperature exhaust gas 8 after extracting the power discharged from the gas turbine 9 is guided to the waste heat recovery boiler 10, and the air compressor The compressed air 15 having a temperature of about 400 ° C. compressed by the heating device 2 is heated by the heater 11. After that, the exhaust gas 8 is further cooled by heating the condensate for generating steam that has passed through the condenser 18 by the steam heater 13 and discharged from the chimney 20. On the other hand, the superheated steam 14 discharged from the tubular steam superheater 6 drives the steam turbine 17, and the rotational power of the turbine shaft is used for power generation. The low-pressure, low-temperature steam after driving the steam turbine 17 is cooled by the condenser 18, and the rotation of the steam turbine is increased by generating a negative pressure.
It returns to 0 and is reused. In a conventional combined cycle power generation combined with a regenerative gas turbine system, FIG.
As shown in the figure, the high-temperature combustion gas 7 discharged from the combustor 4 was directly sent to the gas turbine 9, but if the temperature of the combustion gas is high, the life of the gas turbine 9 is shortened.
It was necessary to increase the amount of compressed air from the air compressor 2 and adjust it to about 1350 ° C. or less. That is, while the amount of compressed air is increased by the air conditioner 2 and the combustion gas 7 whose temperature is lowered is sent to the gas turbine 9 to take out power, a part of the power is used for air compression of the air compressor 2 and the remaining power is used. Used for power generation. On the other hand, in the exhaust gas 8 of the gas turbine, first, the compressed air 15 is heated by the heater 11 to be the heated compressed air 16, and then the steam heater 13 is heated.
Since the steam 14 'generated was sent to the steam turbine 17 at a low temperature of about 400 ° C., an increase in power generation due to the rotation of the steam turbine could not be expected. However, in the present invention, by introducing the tubular steam superheater, the temperature of the combustion gas 7 for generating power by the gas turbine 9 can be reduced, and the steam 14 ′ for generating power by the steam turbine 17 can be reduced. The temperature can be raised. Table 1 shows that in the system of FIGS.
Fuel (natural gas) calculated under certain reasonable conditions
The energy balance per unit amount is shown together. From Table 1, it can be seen that the system of FIG. 1 according to the method of the present invention has a higher total power generation efficiency per unit fuel amount than the system of the conventional system of FIG. [Table 1] According to the present invention, the power generation efficiency can be remarkably improved only by changing a part of the system of the power generation apparatus for the regenerative gas turbine combined cycle power generation. Higher efficiency is due to an increase in the amount of power generated by the steam turbine and a reduction in waste energy. It is also possible to reduce the amount of combustion exhaust gas by increasing the amount of power generation, and to reduce environmental pollution due to hot wastewater by reducing the amount of waste energy. Was.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing an example of a regenerative gas turbine combined cycle power generation system according to the method of the present invention. FIG. 2 is an explanatory view showing an example of a conventional regenerative gas turbine combined cycle power generation system.

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Claims (1)

(57) [Claim 1] A high temperature and high pressure combustion gas obtained by supplying compressed air and fuel to a combustor drives a gas turbine to generate power, and a combustion exhaust gas driving the gas turbine. To a waste heat recovery boiler equipped with a heat exchanger to heat compressed air supplied to a combustor of the gas turbine and to generate steam by a steam turbine as a heat source for generating steam for combined cycle power generation. Providing a tubular steam heater between the combustor and the gas turbine using the high-temperature and high-pressure combustion gas as a heating source, and guiding the steam generated by the waste heat recovery boiler to superheat the obtained superheated steam. And supplying the steam to the steam turbine.