JPH06212910A - Electric power generating plant - Google Patents

Abstract

PURPOSE:To reduce the charge of fuel required to obtain specified gas turbine inlet gas temperatures. CONSTITUTION:A heat exchanger 31 for heating at least either one of the air 5 and the fuel 3 fed into a combustor 2 located at the gas turbine inlet by using the heat of the exhaust gas 7 of gas turbine 1 introduced into an exhaust gas boiler 8 or a chimney, is provided. Or a heat exchanger for heating the air 5 and/or the fuel 3 by using the steam generated in the exhaust gas boiler 8 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined power plant using a gas turbine and a steam turbine and a power plant using a gas turbine.

[0002]

2. Description of the Related Art FIG. 8 shows a conventional combined power plant using a gas turbine and a steam turbine. In FIG. 8, the gas turbine 1 has a combustor 2 for supplying fuel 3 to a compressor 4
The gas generated by burning with the air 5 from is supplied, and the generator 6 is driven. Then, the exhaust gas 7 of the gas turbine 1 is introduced into the exhaust gas boiler 8 and the superheater 9, the evaporator 10 and the economizer 1 installed therein.
1 is sequentially discharged to the atmosphere from the chimney, but the economizer 11 heats the feed water from the condenser, the evaporator 10 generates steam, and the superheater 9 superheats the steam sent to the steam turbine. To do.

Next, FIG. 9 shows a conventional power plant using a gas turbine. In FIG. 9, the gas turbine 21
The fuel 23 in the combustor 22 and the air 2 from the compressor 24.
The gas generated by the combustion by 5 is supplied, and the generator 26 is driven. And the gas turbine 2
The exhaust gas 27 of No. 1 is cooled by a cooler 28 using water or steam to a temperature not higher than an allowable temperature of a gas turbine exhaust duct 29, and is guided to an exhaust gas boiler or a chimney.

Conventionally, such a cooler 28 is installed at the outlet of the gas turbine 21 for the following reason. That is, one of the means for increasing the efficiency of the gas turbine power plant is to raise the gas temperature at the gas turbine inlet. At this time, if the gas turbine inlet gas temperature rises,
Along with this, the temperature of the gas turbine outlet gas, that is, the temperature of the gas turbine exhaust 27 also rises. Normally, the gas turbine exhaust 27 is put into an exhaust gas boiler to generate steam, and the steam turbine power generation plant generates electric power to form a combined power generation plant. In this case, the outlet of the gas turbine 21 and the exhaust gas boiler are connected by the duct 29 to guide the gas turbine exhaust 27 to the exhaust gas boiler. However, as the gas temperature at the gas turbine inlet increases, the gas turbine exhaust 27
Of the gas turbine exhaust duct 29, that is, the upper limit temperature of the material (generally carbon steel or alloy steel is used) constituting the duct (about 600 ° C.).
Temperature), a cooler 28 using water or steam is installed at the exit of the gas turbine 21 to remove the gas turbine exhaust 2
7 is cooled so that the temperature thereof becomes equal to or lower than the allowable temperature of the gas turbine exhaust duct 29.

[0005]

The conventional combined cycle power generation plant shown in FIG. 8 has the following problems. That is, one of the means for improving the efficiency of the combined cycle power plant is to raise the gas temperature at the gas turbine inlet for the purpose of improving the gas turbine power generation efficiency, and the development of the gas turbine has been greatly advanced in recent years. However, in order to increase the gas turbine inlet gas temperature to obtain a predetermined gas turbine inlet gas temperature, there is a problem that the amount of fuel injected into the combustor at the gas turbine inlet increases.

When the gas temperature at the inlet of the gas turbine is increased, the exhaust temperature of the gas turbine also rises.
The heat recovery amount in the exhaust gas boiler increases and the steam turbine output increases. However, an increase in the steam turbine output, that is, the steam turbine outlet steam amount increases the amount of heat that is lost as a loss from the condenser, that is, the steam turbine plant loss. Therefore, in order to further improve the efficiency of the combined cycle power plant, it is necessary to improve the efficiency of the gas turbine plant without increasing the output of the steam turbine plant.

Next, the conventional gas turbine power plant shown in FIG. 9 has the following problems. That is, in order to increase the temperature of the gas turbine inlet gas temperature to obtain a predetermined gas turbine inlet gas temperature for the purpose of improving the efficiency of the gas turbine power plant, as in the conventional combined power plant shown in FIG. There is a problem that the amount of fuel injected into the combustor at the gas turbine inlet increases.

When the gas temperature at the gas turbine inlet is increased, the exhaust gas temperature of the gas turbine also rises.
Due to the relationship with the heat resistant temperature of the gas turbine exhaust duct, if the temperature is higher than the predetermined temperature (about 600 ° C as described above), install a gas temperature cooler with water or steam at the gas turbine outlet to lower the gas turbine exhaust temperature. Currently, the temperature of the gas turbine exhaust is lowered by heating water or steam, but in this case, the power generation ratio on the water cycle (Rankin cycle) side rises, and the efficiency of the entire plant decreases. There is.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and can reduce the amount of fuel input required to obtain a predetermined gas turbine inlet gas temperature, and the loss from the condenser. It is an object of the present invention to provide a combined power generation plant that can reduce the amount of heat that is discarded as.

Further, according to the present invention, the amount of fuel input required to obtain a predetermined gas turbine inlet gas temperature can be reduced, and the gas turbine exhaust temperature can be lowered without increasing the ratio on the water cycle side to improve plant efficiency. It is an object of the present invention to provide a gas turbine power generation plant that can prevent the deterioration of fuel consumption.

[0011]

In order to achieve the former object, the present invention according to claim 1 is an electric power generation equipped with an exhaust gas boiler which is supplied with exhaust gas of a gas turbine to generate steam for driving a steam turbine. In the plant, there is provided a heat exchanger that heats at least one of air and fuel introduced into the combustor at the gas turbine inlet by using heat of the gas turbine exhaust introduced into the exhaust gas boiler.

Also, in order to achieve the former object, the present invention according to claim 2 is a power generation plant equipped with an exhaust gas boiler which is supplied with exhaust gas of a gas turbine to generate steam for driving a steam turbine, A heat exchanger is provided for heating at least one of air and fuel injected into the combustor at the gas turbine inlet by using the steam generated in the exhaust gas boiler.

Further, in order to achieve the latter object, the present invention according to claim 3 is, in a power plant using a gas turbine, using exhaust heat of the gas turbine to introduce the gas into a combustor at an inlet of the gas turbine. A heat exchanger for heating at least one of the air and the fuel to be generated is provided.

[0014]

According to the first aspect of the present invention, the air for combustion of the gas turbine and / or the fuel is heated (preheated) by the exhaust heat of the gas turbine before being introduced into the combustor. The amount of fuel input required to obtain the gas temperature can be kept low. In addition, part of the heat input to the exhaust gas boiler is used as combustion air for the gas turbine and / or
Alternatively, by giving it to the fuel, the heat quantity of the steam input to the steam turbine obtained from the exhaust gas boiler decreases, the steam turbine output in the combined cycle power plant decreases, and the heat quantity discarded as a loss from the condenser also decreases. To do.

According to the present invention as set forth in claim 2,
Heating with combustion steam and / or fuel of the gas turbine with steam generated in the exhaust gas boiler (preheating) before introducing it into the combustor
By doing so, it is possible to suppress the amount of fuel input required to obtain a predetermined gas turbine inlet gas temperature.
Further, by giving the heat quantity of the gas turbine exhaust to the combustion air and / or fuel of the gas turbine, the heat quantity given to the steam turbine cycle is reduced, and the heat quantity discharged as a loss from the condenser is also reduced.

Further, according to the present invention as set forth in claim 3,
By heating (preheating) the gas turbine combustion air and / or fuel with the gas turbine exhaust heat before introducing it into the combustor, the amount of fuel input required to obtain a predetermined gas turbine inlet gas temperature is kept low. be able to. Further, since the temperature of the exhaust gas of the gas turbine is reduced by heat exchange with the gas turbine combustion air and / or the fuel, the ratio on the water cycle side is not increased, so that the reduction of the plant efficiency can be prevented.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

1 to 4 show four different embodiments of the present invention according to claim 1, the same parts as those shown in FIG. 8 are designated by the same reference numerals, and overlapping description will be omitted. Omit it.

First, the embodiment shown in FIG. 1 uses the heat of the exhaust gas 7 of the gas turbine 1 introduced into the exhaust gas boiler 8 in the combined cycle power plant, and the air 5 introduced into the combustor 2 at the inlet of the gas turbine 1 A heat exchanger for heating the heat exchanger, which is an air heat transfer surface type heat exchanger 31 in this embodiment, is provided between the superheater 9 and the evaporator 10 in the exhaust gas boiler 8.

By providing such a heat exchanger 31 to heat the air 5 at the outlet of the compressor 4 of the gas turbine 1, that is, the air 5 introduced into the combustor 2 at the inlet of the gas turbine 1, a predetermined gas turbine is obtained. The amount of fuel input required to obtain the inlet gas temperature can be reduced. Further, since this heating is performed by using the heat input to the exhaust gas boiler 8, that is, the heat of the gas turbine exhaust 7, it is possible to effectively utilize the heat of the gas turbine exhaust without discarding it outside the system.
Further, although the amount of heat applied to the steam turbine plant side is reduced by this, the amount of heat discharged from the condenser of the steam turbine plant to the outside of the system is correspondingly reduced, so that the efficiency of the entire combined cycle power plant is increased. As described above, the power generation efficiency of the combined cycle power generation plant, that is, the ratio of the total amount of generated power to the heat input of the fuel increases.

The arrangement of the heat exchanger 31 and the superheater 9 is changed according to the relationship between the gas temperature, the air temperature and the steam temperature, and the gas turbine exhaust 7 is first introduced into the combustor 2 at the inlet of the gas turbine 1. The air 5 may be heated and then the steam may be superheated.

Next, in the embodiment shown in FIG. 2, the heat of the exhaust gas 7 of the gas turbine 1 that is input to the exhaust gas boiler 8 is used to input the gas to the combustor 2 at the inlet of the gas turbine 1 in the combined cycle power plant. A heat exchanger for heating the air 5, a heat pipe type heat exchanger 32 in this embodiment, is provided so that the combustion air 5 of the gas turbine 1 is heated by the gas turbine exhaust 7 before being introduced into the combustor 2. It was done like this. Therefore, according to this embodiment, the same operational effect as that of the embodiment shown in FIG. 1 can be obtained.

In this embodiment, the heat transfer surface of the heat pipe heat exchanger 32 in the exhaust gas boiler 8 is provided between the superheater 9 and the evaporator 10. However, the gas temperature, the air temperature, and the steam temperature By changing the arrangement of the heat transfer surface and the superheater 9, the gas turbine exhaust 7 first heats the air 5 introduced into the combustor 2 at the inlet of the gas turbine 1, and then superheats the steam. You may do it.

Further, in the present embodiment, the heat of the gas turbine exhaust 7 is used to heat the air 5 that is introduced into the combustor 2 at the inlet of the gas turbine 1. However, as shown in FIG. Alternatively, even if the fuel 3 charged into the combustor 2 is heated by the heat pipe heat exchanger 33, or both the air 5 and the fuel 3 are heated by the heat pipe heat exchanger 34 as shown in FIG. 4, The same operational effect as described above can be obtained.

In the embodiment shown in FIG. 3, the heat exchanger 33 for heating the fuel 3 charged into the combustor 2 at the inlet of the gas turbine 1 is of the heat pipe type, but may be of another type such as a steel pipe type. It may be a heat exchanger. Further, in the embodiment shown in FIG. 4, the fuel 3 injected into the combustor 2 at the inlet of the gas turbine 1
The two heat transfer surfaces of the heat pipe type heat exchanger 34 for heating the air 5 and the air 5 are connected in series, but the fuel 3 and the air 5 are heat exchanges such as separate heat pipe type or steel pipe type. You may make it heat with a container.

Next, FIG. 5 shows an embodiment of the present invention as set forth in claim 2. The same parts as those shown in FIG. 8 are designated by the same reference numerals, and the duplicated description will be omitted. . In the embodiment shown in FIG. 5, heat exchangers 35 and 36 that heat the air 5 and the fuel 3 introduced into the combustor 2 at the inlet of the gas turbine 1 by using the steam generated in the exhaust gas boiler 8, respectively.
Is provided.

By providing such heat exchangers 35 and 36,
Required to obtain a predetermined gas turbine inlet gas temperature by heating the combustion air 5 and the fuel 3 of the gas turbine 1 with the steam generated in the exhaust gas boiler 8 before introducing them into the combustor 2 at the inlet of the gas turbine 1. It is possible to keep the amount of fuel input low. Further, since the heat quantity of the gas turbine exhaust 7 is given to the combustion air 5 and the fuel 3 of the gas turbine, the heat quantity given to the steam turbine cycle is reduced, and the heat quantity discharged as a loss from the condenser is also reduced. The efficiency of the entire power plant increases. As described above, the power generation efficiency of the combined cycle power generation plant, that is, the ratio of the total amount of generated power to the heat input of the fuel increases.

In this embodiment, the steam (main steam) superheated by the superheater 9 in the exhaust gas boiler 8 is replaced by the heat exchangers 36, 35.
Are sequentially supplied to heat the fuel 3 and the air 5, and then the main steam is superheated by the superheater 37 newly provided in the exhaust gas boiler 8 and sent to the steam turbine. Alternatively, reheat steam may be used.

In this embodiment, the steam generated in the exhaust gas boiler 8 is used to heat both the combustion air 5 and the fuel 3 of the gas turbine. However, one of the air 5 and the fuel 3 is heated. Even in this case, the same operational effect as described above can be obtained.

Next, FIGS. 6 and 7 show two different embodiments of the present invention described in claim 3, and the same parts as those shown in FIG. The description will be omitted.

First, in the embodiment shown in FIG. 6, in a gas turbine power plant, a heat exchanger 38 for heating the air 25 introduced into the combustor 22 at the inlet of the gas turbine 21 by using the heat of the exhaust 27 of the gas turbine 21. Is provided. By providing such a heat exchanger 38 and heating the combustion air 25 of the gas turbine with the exhaust heat of the gas turbine before introducing it into the combustor 22, it is necessary to obtain a predetermined gas turbine inlet gas temperature. The amount of fuel input can be kept low. Also, by lowering the gas turbine exhaust temperature by exchanging heat with the combustion air of the gas turbine,
Since the operation is performed without increasing the ratio on the water cycle side, it is possible to prevent a decrease in plant efficiency.

Next, in the embodiment shown in FIG. 7, in the gas turbine power plant, a heat exchanger 39 for heating the fuel 23 of the gas turbine by using the heat of the exhaust 27 of the gas turbine 21 is provided to burn the fuel 23. The gas turbine exhaust 27 is heated by the heat before it is charged into the container 22. Therefore, according to this embodiment, the same operational effect as that of the embodiment shown in FIG. 6 can be obtained.

In the embodiment shown in FIG. 6, the air 25 introduced into the combustor 22 at the inlet of the gas turbine 21 is introduced, and in the embodiment shown in FIG. 7, the air 25 is introduced into the combustor 22 at the inlet of the gas turbine 21. Although the fuel 23 is heated by using the heat of the gas turbine exhaust 27, the same effect as described above can be obtained by heating both the air 25 and the fuel 23.

Also in each of the embodiments shown in FIGS. 6 and 7, as in the conventional example shown in FIG. 9, the temperature of the gas turbine exhaust 27 is controlled by the heat exchangers 38 and 39 in the gas turbine exhaust duct 29. Since it can be lowered to the allowable temperature or lower, the existing material such as alloy steel can be used as the material of the duct 29.

[0035]

As described above, according to the present invention as set forth in claims 1 and 2, in the combined power generation plant using the gas turbine and the steam turbine, the heat of the gas turbine exhaust fed to the exhaust gas boiler or By using the steam generated in the exhaust gas boiler, by heating at least one of the air and fuel that are input to the combustor at the gas turbine inlet,
Since the amount of fuel input required to obtain a predetermined gas turbine inlet gas temperature can be reduced and the amount of heat discarded from the condenser of the steam turbine cycle can be reduced, the efficiency of the combined cycle power plant can be increased.

According to the third aspect of the present invention, in a power plant using a gas turbine, at least one of air and fuel injected into the combustor at the inlet of the gas turbine is heated by using heat of exhaust gas from the gas turbine. By this, it is possible to reduce the amount of fuel input required to obtain a predetermined gas turbine inlet gas temperature, and to lower the gas turbine exhaust temperature by heat exchange with combustion air and / or fuel for the gas turbine. Since it is performed without increasing the ratio on the water cycle side, it is possible to prevent a decrease in gas turbine power plant efficiency.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a power plant according to the present invention according to claim 1.

FIG. 2 is a system diagram showing another embodiment of the power plant according to the present invention as defined in claim 1;

FIG. 3 is a system diagram showing still another embodiment of the power plant according to the present invention as defined in claim 1;

FIG. 4 is a system diagram showing still another embodiment of the power plant according to the present invention according to claim 1;

FIG. 5 is a system diagram showing an embodiment of a power plant according to the present invention as set forth in claim 2.

FIG. 6 is a system diagram showing an embodiment of a power plant according to the present invention as set forth in claim 3.

FIG. 7 is a system diagram showing another embodiment of the power plant according to the present invention as defined in claim 3;

FIG. 8 is a system diagram showing an example of a conventional power generation plant.

FIG. 9 is a system diagram showing another example of the conventional power plant.

[Explanation of symbols]

 1 Gas Turbine 2 Combustor 3 Fuel 4 Compressor 5 Air 7 Exhaust 8 Exhaust Gas Boiler 21 Gas Turbine 22 Combustor 23 Fuel 24 Compressor 25 Air 27 Exhaust 31 Heat Exchanger 32 Heat Exchanger 33 Heat Exchanger 34 Heat Exchanger 35 Heat Exchanger 36 Heat Exchanger 38 Heat Exchanger 39 Heat Exchanger

Claims (3)

[Claims] 1. In a power plant equipped with an exhaust gas boiler that receives the exhaust gas of a gas turbine to generate steam for driving a steam turbine, the heat of the gas turbine exhaust gas that is input to the exhaust gas boiler is used to enter the gas turbine inlet. Power plant having a heat exchanger for heating at least one of air and fuel fed into the combustor. 2. In a power plant equipped with an exhaust gas boiler, which is supplied with exhaust gas of a gas turbine to generate steam for driving a steam turbine, the steam generated in the exhaust gas boiler is used to supply the gas turbine to a combustor at an inlet thereof. A power generation plant provided with a heat exchanger for heating at least one of air and fuel to be discharged. 3. A power plant using a gas turbine, wherein a heat exchanger for heating at least one of air and fuel introduced into a combustor at an inlet of the gas turbine by using exhaust heat of the gas turbine is provided. Power plant.