JP2008232086A - Gas turbine power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine power generation system capable of cooling intake air without limitation on use environment. <P>SOLUTION: This gas turbine power generation system 20 includes: a compressor 3 compressing air to be sucked to generate compressed air; a combustor 5 burning compressed air compressed in the compressor 3 and fuel; a gas turbine 2 rotated by combustion gas burnt in the combustor 5; a generator 1 driven by the rotation of the gas turbine 2; a thermoelectric generator 6 generating electricity by using waste heat of exhaust gas delivered from the gas turbine 2; and a Peltier cooling part 8 cooling air to be sucked into the compressor 3 by receiving electric power distribution from the thermoelectric generator 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power generation system using a gas turbine, and more particularly to a technique for improving power generation efficiency by cooling air taken into a gas turbine.

The gas turbine is mainly composed of an air inlet, a compressor, a combustion chamber, a turbine, and an exhaust port, and air taken in for mixing with fuel before ignition of the air-fuel mixture in the combustion chamber (hereinafter referred to as intake air). Is compressed, and hot gas is generated by ignition to drive the turbine. When the temperature of the intake air increases, the mass per volume decreases, and the output of the gas turbine decreases. Therefore, for example, there is a concern about a decrease in the output of the gas turbine in the summer. Moreover, in the tropical region, there is a problem that the output of the gas turbine is reduced not only in summer. In order to improve power generation efficiency by cooling the intake air, several techniques for cooling the intake air have been proposed.
For example, a method of cooling intake air using the heat of vaporization of LNG (liquefied natural gas) (Patent Documents 1 to 3), a method of cooling intake air using an ice heat storage device (Patent Documents 4 to 6), A method for cooling intake air using a direct evaporative cooling device is known (Patent Document 7).

Japanese Patent Publication No.59-2771 JP-A-1-142219 JP-A-6-173710 JP-A-7-19067 JP-A-7-180566 Japanese Patent No. 2851794 JP-A-7-166888

However, the method of cooling the intake air using the heat of vaporization of LNG is limited to the case where a gas turbine using LNG as fuel or an LNG plant is attached.
In addition, the method of cooling intake air using an ice heat storage device is premised on the use of nighttime power for ice heat storage, and is therefore difficult to use in tropical regions where nighttime power is insufficient. In the case of a system that stops power generation at night, the ice heat storage device using this power generation does not function.
Furthermore, in the method of directly cooling the intake air using the evaporative cooling device, the direct evaporative cooling device does not function unless the relative humidity is 75% or more. Therefore, sufficient cooling cannot be obtained in a tropical region where the relative humidity is high. .

  The present invention has been made based on such a technical problem, and an object of the present invention is to provide a gas turbine power generation system capable of cooling intake air without being restricted by the use environment.

  The inventors of the present invention studied a system that generates power using waste heat of a gas turbine and cools intake air using the power generated by the power generation. When power generation is performed using the waste heat of the gas turbine, the intake air can be cooled without being restricted by the use environment as long as the gas turbine is operated. On the other hand, the equipment for cooling the intake air is desired to be as small as possible. In view of the above, the gas turbine power generation system of the present invention includes a compressor that compresses sucked air to generate compressed air, a combustor that burns compressed air and fuel compressed by the compressor, and a combustor A gas turbine that is rotated by the combustion gas burned in the gas turbine, a generator that is driven by the rotation of the gas turbine, a thermoelectric power generation unit that generates power using waste heat of exhaust gas discharged from the gas turbine, and a thermoelectric And a Peltier cooling unit that receives supply of electric power from the power generation unit and cools air taken into the compressor. In addition, in this invention, a thermoelectric power generation part means what produces electric power using a thermoelectric element. Moreover, in this invention, a Peltier cooling part means what cools using a Peltier device.

  In the gas turbine power generation system of the present invention, it is preferable that a path for supplying a part of the air cooled by the Peltier cooling unit to the thermoelectric power generation unit is provided. A thermoelectric element used in the thermoelectric power generation unit needs a predetermined temperature difference for power generation. In the present invention, a high temperature for obtaining the temperature difference is obtained by waste heat of exhaust gas, while a low temperature is obtained by air cooled by a Peltier cooling unit.

As described above, the gas turbine power generation system according to the present invention can cool the intake air by the Peltier cooling unit. Therefore, even if the outside air temperature is high, a decrease in the output of the gas turbine can be suppressed or the output can be improved. Moreover, since the Peltier cooling part can be comprised by arrange | positioning the unit provided with two or more Peltier elements in an appropriate place, it can make an equipment space small.
In the gas turbine power generation system according to the present invention, the electric power supplied to the Peltier cooling unit is obtained by the thermoelectric power generation unit using the exhaust gas from the gas turbine. Therefore, the intake air can be cooled without depending on the external power supply. This means that as long as the gas turbine is operated, it is possible to suppress a decrease in the output of the gas turbine or improve the output without being influenced by the surrounding environment.
Furthermore, in the gas turbine power generation system according to the present invention, the thermoelectric power generation unit can obtain a high temperature state using the exhaust gas from the gas turbine, and the low temperature state can be performed even at room temperature. A low-temperature state can be obtained using the air cooled in (1). Therefore, this gas turbine power generation system has an advantage that a high temperature state and a low temperature state for generating power by the thermoelectric power generation unit can be realized in the system.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a block diagram showing a configuration of a gas turbine power generation system 20 according to the present invention.
As shown in FIG. 1, the gas turbine power generation system 20 arranges the generator 1, the gas turbine 2, and the compressor 3 on the same rotating shaft 4 as a basic structure concerning electric power generation. Then, air and fuel compressed by the compressor 3 are supplied to the combustor 5 and burned, and the gas turbine 2 is rotated by the combustion gas to drive the generator 1 to generate power. Needless to say, conventionally known techniques can be used as appropriate for the above basic configuration.

In addition to the basic configuration described above, the gas turbine power generation system 20 generates power using the exhaust gas discharged from the gas turbine 2 and cools the intake air with the electric power obtained by the power generation. It has a configuration.
That is, in the gas turbine power generation system 20, the thermoelectric power generation unit 6 is provided on the exhaust gas path 7 of the gas turbine 2. The thermoelectric power generation unit 6 generates power using the waste heat of the exhaust gas discharged from the gas turbine 2. In the gas turbine power generation system 20, the Peltier cooling unit 8 is provided on the suction path 9. The Peltier cooling unit 8 cools the intake air with the electric power generated by the thermoelectric power generation unit 6. In order to supply the power generated by the thermoelectric power generation unit 6 to the Peltier cooling unit 8, the thermoelectric power generation unit 6 and the Peltier cooling unit 8 are connected by a power supply line 10.

The thermoelectric power generation unit 6 includes a thermoelectric element as a main component. Generally, a thermoelectric element is formed by joining a p-type semiconductor and an n-type semiconductor to form a circular circuit. When one of the junctions is heated to a high temperature and the other is cooled to a low temperature, a potential difference is generated at both ends and current flows. Is. The present invention uses the exhaust gas discharged from the gas turbine 2 in order to increase the temperature of the one.
In this invention, the material which comprises a thermoelectric element is not limited, A well-known material can be used suitably. However, since the operating temperature range is limited depending on the material, it is necessary to determine the part where the thermoelectric generator 6 is installed according to the material. For example, BiTe-based thermoelectric element materials are effective in a temperature range from room temperature to about 300 ° C., PbTe-based thermoelectric element materials are in a temperature range of 300-600 ° C., and SiGe-based thermoelectric element materials are effective in a temperature range of 600-900 ° C. It is. The temperature of the exhaust gas from the gas turbine 2 is 500 to 700 ° C., but any thermoelectric element material can be used depending on the position where the thermoelectric power generation unit 6 is installed on the exhaust gas path 7. Even when a BiTe-based thermoelectric element material is used, the thermoelectric power generation unit 6 may be installed at a position away from the gas turbine 2.

  The present invention can use the air cooled by the Peltier cooling unit 8 in order to obtain the low temperature side of the thermoelectric element. Therefore, the gas turbine power generation system 20 is provided with a cooling air branch path 11 that branches from the suction path 9. The cooling air supplied to the cooling air branch 11 flows into the thermoelectric generator 6. Here, air cooled by the Peltier cooling unit 8 is used. However, when the temperature of the atmosphere is low, the atmosphere can be taken into the thermoelectric power generation unit 6. A low temperature fluid can also be used.

FIG. 2 shows a configuration example of a thermoelectric unit 30 including a plurality of thermoelectric elements.
The thermoelectric unit 30 includes a heat sink 31 and a plurality of thermoelectric elements 32 disposed on one surface of the heat sink 31. The heat sink 31 is made of a material having excellent thermal conductivity such as copper or copper alloy. A flow path through which the cooling medium flows is formed inside the heat sink 31. As the cooling medium, the above-described cooling air can be used in the present invention. The thermoelectric element 32 has the configuration described above. In the thermoelectric unit 30, the thermoelectric element 32 is formed on one surface of the heat sink 31, but as shown in FIG. 3, it may be a thermoelectric unit 30 formed on both front and back surfaces. In the present invention, the thermoelectric power generation unit 6 is configured by using a plurality of thermoelectric units 30 as shown in FIG.

  In the present embodiment, the position where the thermoelectric unit 30 is disposed is not limited. What is necessary is just to arrange | position in the position which can generate electric power using the waste heat of the exhaust gas from the gas turbine 2. FIG. For example, a plurality of thermoelectric units 30 can be arranged on the outer wall of the exhaust tower so as to surround the exhaust tower of the gas turbine 2. In this case, if the thermoelectric unit 30 shown in FIG. 2 is used, the side on which the thermoelectric element 32 is disposed is opposed to the outer wall. In addition, the exhaust tower constitutes the main body of the gas turbine 2, but the thermoelectric unit 30 can be disposed in a portion where the exhaust gas discharged from the main body of the gas turbine 2 flows. The pipe line through which the exhaust gas flows is generally called an exhaust flue. The exhaust flue has the concept of including an exhaust duct and an exhaust chimney. FIG. 4 schematically shows an example in which a plurality of thermoelectric units 40 are arranged in parallel in the exhaust flue 50. In this case, it is preferable to use the thermoelectric unit 40 shown in FIG. 3 in which the thermoelectric elements 32 are disposed on both the front and back surfaces of the heat sink 31. This is an example of the arrangement of the thermoelectric unit 30 (40), and the exhaust flue 50 may be divided and the thermoelectric unit 30 may be attached to the side wall of the divided region.

  The thermoelectric power generation unit 6 set as described above generates power by using the high temperature due to the waste heat of the exhaust gas of the gas turbine 2 and the low temperature due to the air cooled by the Peltier cooling unit 8, and the power supply line Electric power is supplied to the Peltier cooling unit 8 through 10.

The Peltier cooling unit 8 cools the air sucked into the compressor 3 using the electric power generated by the thermoelectric power generation unit 6.
The Peltier cooling unit 8 includes a Peltier element as a main component. In the Peltier device, when a current is passed through the pn junction, an endothermic phenomenon occurs in the n → p junction and a heat dissipation phenomenon occurs in the p → n junction. This is called the Peltier effect. While the thermoelectric element produces electricity from heat, the Peltier element can be understood as transferring heat from the low temperature side (heat absorption side) to the high temperature side (heat generation side) by flowing electricity.
The material constituting the Peltier element basically matches the material constituting the thermoelectric element. That is, a Peltier element can be manufactured using a known material such as a BiTe-based material, a PbTe-based material, and a SiGe-based material.

Since the Peltier cooling unit 8 cools the air sucked into the compressor 3, the Peltier cooling unit 8 needs to be disposed in front of the compressor 3. Usually, the compressor 3 is provided with an intake tower, and air is sucked into the compressor 3 through the intake tower. Therefore, a plurality of Peltier cooling units 8 can be arranged in the intake tower. However, the present invention is not limited to the intake tower, and the present invention includes a wide range of positions where the intake air can be cooled.
Here, FIG. 5 shows a configuration example of a Peltier unit 60 including a plurality of Peltier elements.
The Peltier unit 60 includes a heat sink 61 and a plurality of Peltier elements 62 disposed on one surface of the heat sink 61. The heat sink 61 is made of a material having excellent thermal conductivity such as copper or copper alloy. An electric wire for supplying power to the Peltier element 62 is connected to the heat sink 61. By supplying electric power, heat is transferred to the surface side of the Peltier element 62 that is in contact with the heat sink 61, and the temperature of the surface that is open to the outside air decreases. Due to this temperature decrease, the temperature of the intake air is decreased.
A plurality of Peltier units 60 may be attached to the inner wall of the intake tower. In this case, it is necessary to arrange the heat sink 61 so as to face the inner wall of the intake tower. In addition to attaching to the inner wall of the intake tower, a plurality of Peltier units 60 may be arranged in parallel inside the intake tower as shown in FIG. In this case, it is preferable to use a Peltier unit in which Peltier elements 62 are disposed on both the front and back surfaces of the heat sink 61.

As described above, the gas turbine power generation system 20 according to the present embodiment can lower the temperature of the air sucked into the compressor 3 by the Peltier cooling unit 8. Therefore, even if the outside air temperature is high, a decrease in the output of the gas turbine 2 can be suppressed or the output can be improved.
In the gas turbine power generation system 20 according to the present embodiment, the electric power supplied to the Peltier cooling unit 8 is generated by the thermoelectric power generation unit 6 using the exhaust gas from the gas turbine 2. Therefore, the intake air can be cooled without depending on the external power supply. This means that as long as the gas turbine 2 is in operation, the output of the gas turbine 2 can be prevented from decreasing or the output can be improved without being influenced by the surrounding environment.
Further, in the gas turbine power generation system 20 according to the present embodiment, the thermoelectric power generation unit 6 uses the exhaust gas from the gas turbine 2 to be in a high temperature state, and the air cooled by the Peltier cooling unit 8 is low temperature. Getting the state. Therefore, the gas turbine power generation system 20 has an advantage that a high-temperature state and a low-temperature state for generating power by the thermoelectric power generation unit 6 can be realized within the relationship.

  Although the gas turbine power generation system 20 described above generates power by the thermoelectric power generation unit 6, the gas turbine power generation system of the present invention can use solar power generation in combination. This is particularly effective in tropical areas.

Next, an estimate of performance improvement by the gas turbine power generation system using the present invention will be shown. It is assumed that the thermoelectric unit is arranged in the flue and the Peltier unit is arranged in the intake tower.
(1) Power generation amount of thermoelectric unit determined from flue area It is assumed that there are 30 fluees with a width of 30 cm, a length of 2 m, and a length of 10 m.
The area of each flue becomes 40 m ² on the front and back of 2m × 10m = 20m ^2. Since there are 30 flues, the total area is 1200 m ^{2 according} to the following.
40 m ² × 30 = 1200 m ²
On the other hand, if a thermoelectric unit having 12 cm × 30 cm = 360 cm ² and a power generation capacity of 50 W / h is used, the power generation amount per unit area is 1.388 KW / m ^{2 as} follows.
^{50W / h ÷ 0.036m 2 = 1.388KW} / m 2
Assuming that the thermoelectric unit is attached to both sides of each flue without any gap, a power generation amount of 1665.6 KW / h can be obtained as follows.
1200 m ² × 1.388 KW / m ² = 1665.6 KW / h

(2) Peltier unit heat absorption obtained from power generation amount A Peltier unit that consumes 1.05 kW and has a heat absorption of 400 W shall be used.
If the amount of power generated by the thermoelectric unit is used for cooling as it is, this Peltier unit can absorb 634.514 KW as follows.
(1665.6 kW ÷ 1.05 kW) × 400 W = 634514 W = 634.514 kW

(3) Gas Turbine Air Consumption A gas turbine that consumes approximately 650 kg / sec of air is assumed.
Since the weight per 1 m ³ of air (15 ° C.) is 1.293 kg, the consumption amount per unit time of the gas turbine is 650 kg ÷ 1.293 kg = 502.7 m ³ / sec. One hour will consume 1809720 m ³ / h.

(4) Energy required to lower air by 1 ° C. 310 cal is required to lower 1 m ³ air by 1 ° C. Therefore, in the case of the gas turbine, the required energy is 561013.2 kcal according to the following. Since 1W = 855.999 cal, 561013.2 Kcal = 652.3 KW.
1809720 m ^{3 /} h × 310 cal = 561013.2 kcal

(5) Temperature drop by the Peltier unit As described above, the Peltier unit can absorb 634.514 KW. Thus, according to the following, this Peltier unit results in a temperature drop of 0.97 ° C.
634.514KW ÷ 652.3KW = 0.97 ° C

(6) Gas turbine performance improvement In the case of a gas turbine, if the air temperature drops by 1 ° C., the output will increase by 1%. If the output of the gas turbine is 270 MW / h, the output is improved by 2.6 MW by the following.
270 MW / h × 0.97% = 2.6 MW

It is a block diagram which shows the structure of the gas turbine power generation unit in this Embodiment. (A) of a thermoelectric unit is a side view, (b) is a top view. It is a side view which shows the other example of a thermoelectric unit. It is a perspective view which shows the example which arranges a thermoelectric unit in an exhaust flue. (A) of a Peltier device unit is a side view, (b) is a top view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Gas turbine power generation system, 1 ... Generator, 2 ... Gas turbine, 3 ... Compressor, 4 ... Rotary shaft, 5 ... Combustor, 6 ... Thermoelectric power generation part, 7 ... Exhaust gas path, 8 ... Peltier cooling part, 9 ... Suction path, 10 ... Power supply line, 11 ... Cooling air branch path

Claims (2)

A compressor that compresses inhaled air to generate compressed air;
A combustor for combusting the compressed air and fuel compressed by the compressor;
A gas turbine rotated by combustion gas combusted in the combustor;
A generator driven by rotation of the gas turbine;
A thermoelectric power generation unit that generates power using waste heat of exhaust gas discharged from the gas turbine;
A Peltier cooling unit that receives supply of electric power from the thermoelectric generator and cools air sucked into the compressor;
A gas turbine power generation system comprising:   The gas turbine power generation system according to claim 1, further comprising a path for supplying a part of the air cooled by the Peltier cooling unit to the thermoelectric power generation unit.

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