JPS6359005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combined cycle power generation plant using a plurality of power generation units configured by connecting a gas turbine and a steam turbine.

Generally, a combined cycle power generation plant, which is constructed by combining a gas turbine and a steam turbine, utilizes the high-temperature exhaust gas produced by the gas turbine and exchanges heat with a heat exchanger to generate steam. Steam is used to drive a steam turbine to generate electricity, eliminating wasted thermal energy and effectively reusing exhaust gas.

That is, conventionally, a combined cycle power generation plant that combines a gas turbine and a steam turbine of this type has a compressor (air-based) 1a, a burner (combustor) 2a, as shown in FIGS. 1 and 2.
A gas turbine 3a, a generator 4a, and a steam turbine (condensing steam turbine) 5a are connected to each other by a single turbine shaft (rotating shaft) 6a in a skewer shape. Starting motor 7
A is connected via a clutch 8a, and on the other hand, an exhaust pipe 9a for exhausting the exhaust gas worked by the gas turbine 3a is connected to a waste heat recovery steam generator (also referred to as a heat exchanger or boiler) 10a to exhaust the exhaust gas. The waste heat recovery steam generator 10a is installed in the water supply pipe 11a of the steam turbine 5a via a condenser 12a and a water supply pump 13a, and the waste heat recovery steam generator 10a is installed between the waste heat recovery steam generator 10a and the steam turbine 5a. A main steam stop valve 15a and a steam control valve 16a are sequentially attached to the main steam pipe 14a provided in 17a and a bypass 18a connected to each other.

Therefore, in the conventional combined cycle power generation plant described above, air is pressurized and compressed by the compressor 1a, and then mixed with hot combustion gas injected from the burner 2a and combusted, and this high-temperature combustion gas is used. The gas turbine 3a is driven. However,
The high-temperature exhaust gas that has completed its work is supplied to the waste heat recovery steam generator 10a through the exhaust pipe 9a for heat exchange, and then released into the atmosphere, while the heat exchange is carried out in the waste heat recovery steam generator 10a. The steam generated flows into the steam turbine 5a through the main steam stop valve 15a and the steam control valve 16a of the main steam pipe 14a,
Here, the steam turbine 5a is driven. Furthermore, the steam that has finished its work passes through the water supply pipe 11a to the condenser 1.
2a, the spent steam and water exchange heat in this condenser 12a to generate condensate, and this condenser 12
The condensate produced in step a is returned to the waste heat recovery steam generator 10a by a water supply pump 13a.

On the other hand, the surplus steam in the main steam pipe 14a is
The water is transferred to the condenser 12a through the bypass valve 17a of the bypass 18a.

On the other hand, the startup and operation operations of the above-mentioned combined cycle power plant are as shown in _{the startup schedule shown in the graph of FIG .}
As is clear from the rotation speed characteristic curve a, steam condition characteristic curve a, main steam stop valve opening characteristic curve a, and steam control valve opening characteristic curve a, each rated point is set to 100%. When expressed as a ratio, since there is no drive source to rotate the turbine shaft 6a at startup, first, by driving the startup motor 7a, the rotational speed of the compressor 1a increases to the speed required for igniting the burner 2a. Increase the speed until the rotation speed is reached. Therefore, the time T ₁ in Fig. 2
After it is confirmed that the burner 2a is ignited in the state shown in FIG. Switch to drive of machine 1a. However, the second
During the time T ₁ to T ₂ shown in the figure, the gas turbine 3a
A warm-up will be carried out, but at this point,
The exhaust gas has already reached a high temperature, and the waste heat recovery steam generator 10a gradually starts generating steam.

On the other hand, the main steam stop valve 15a on the steam turbine 5a side gradually starts to open as steam is generated, but the rated steam condition has not yet been reached and the steam control valve 16a is in a fully closed state. No steam flows into the turbine 5a. Therefore, the steam generated in the waste heat recovery steam generator 10a flows into the condenser 12a through the bypass 18a.

Next, after time T2 in FIG. ₂ , as the rotational speed of the turbine shaft 6a gradually increases, the steam temperature also increases, so at this point,
The inside of the steam turbine 5a is in the same vacuum state as the inside of the condenser 12a, and heat is generated because the rotor (not shown) of the steam turbine 5a rotates at the same rotation speed as the gas turbine 3a in this vacuum state. (thermal energy), the steam control valve 16a is slightly opened under arbitrary steam conditions (point _T3 ) to allow steam to flow into the steam turbine 5a, thereby performing cooling that also serves as warming. Eventually, after the temperature of the steam generated in the waste heat recovery steam generator 10a reaches the rated state (point T ₄ ), the external power system is connected synchronously (point T ₅ ), and the steam control valve 16a of,
The steam control valve 16a is returned to the fully closed position again, and the steam control valve 16a is gradually opened according to the load schedule to start increasing the load.

That is, since the steam generated in the waste heat recovery steam generator 10a starts to flow into the steam turbine 5a, the bypass valve 17a slowly closes, and in the rated load state of the steam turbine 5a, the bypass valve 1 closes slowly.
Fully close 7a.

Note that the operation stop operation is performed in the reverse order as described above.

In this way, in the above-described combined cycle power generation Plato, in the rated state, the gas turbine 3a and the steam turbine 5a are powered by the generator 4a based on the determined load sharing ratio based on the fuel supplied to the burner 2a. electricity is generated.

However, since the steam source for the steam turbine reuses the exhaust gas of the gas turbine 3a, the output of a single unit in the conventional combined cycle power plant described above is lower than that of the high-temperature and high-pressure power plants used in general thermal power plants. This is different from the steam conditions, and the output of a single gas turbine is approximately
It is approximately 100MW, making it difficult to obtain large-capacity output. That is, in order to obtain a large-output power generation plant using a combined cycle, one set (one unit) of a power generation unit constituted by a combination of the above-mentioned gas turbine 3a and steam turbine 5a is required. The number of units (number of sets) required is unavoidable.

This can be achieved by adopting an operating method that frequently shuts down at night and on weekends while considering the power generation efficiency of the entire power plant based on the power demand in the combined cycle power plant mentioned above.
Even if automatic operation is implemented, it will be cumbersome as starting and stopping work will be required for each of the power generation units mentioned above, and it is predicted that failure to ignite the burner 2a as a heat sinter may occur due to this. In addition, there is a risk that the power generation unit will be forced to stop, making it impossible to meet the power demand.

Furthermore, when starting each of the above power generating units,
In order to secure power for the number of gas turbines in each power generating unit installed, each starting motor 7a must be installed for each bin shaft 6a via each clutch 8a, which imposes restrictions on installation location. Not only will this increase the amount of money received, but the capital investment will also increase, which poses economic difficulties.

In order to solve the above-mentioned difficulties, the present invention provides a plurality of combined cycle power generation units in parallel, each of which is a combination of a gas turbine and a steam turbine each equipped with a starting motor, and each of the wastes incorporated in each power generation unit. Each reheater is attached to the heat recovery steam generator, each steam line having each switching valve connected to the waste heat recovery steam generator is connected to the steam header, and each reheater is connected to each condenser of each of the above power generation units. A bypass with a bypass valve is attached to each water supply pipe with a connected water pump and water supply valve, and a water supply header is connected to each bypass, thereby flexibly changing the output from small to large capacity. The present invention provides a combined cycle power generation plant which is capable of operating, and which also selectively stops operation of each power generation unit to perform maintenance and inspection when there is surplus power generation.

Hereinafter, an illustrated embodiment in which the present invention is applied to four power generation units will be described. It should be noted that the present invention will be described with the same reference numerals attached to the same constituent members as in the specific example described above.

In FIG. 3, the reference numeral indicates a first power generation unit based on a combined cycle that combines a gas turbine 3a equipped with a starting motor 7a and a steam turbine 5a, and this first power generation unit is
A compressor 1a that compresses air, a gas turbine 3a equipped with a burner 2a, a generator 4a, and a speed governor 5
Steam turbine (condensing steam turbine) with a _{1 5}
Turbine shaft (rotating shaft) 6a so that a forms a skewer shape
It is connected and installed. That is, a starting motor 7a is connected to one end of the turbine shaft 6a via a clutch 8a 1, and a rotating shaft 6a ₁ of the generator 4a provided between the gas turbine 3a and the steam turbine 5a is connected to one end of the turbine shaft _6a . A pair of clutches 8a ₂ , 8a ₃
It is connected to the turbine shaft 6a via. On the other hand, the exhaust gas that has finished its work in the gas turbine 3a is transferred through an exhaust pipe 9a to a waste heat recovery steam generator (heat exchanger) _10a equipped with a reheater (also referred to as a reburner) 10a1. Here, water supply pipe 1
It exchanges heat with the water in 1a to generate steam. The reheater 10a ₁ is provided to increase the enthalpy of steam when the enthalpy is low, thereby improving the efficiency of the power generation plant.

On the other hand, the water supply pipe 11a of the steam turbine 5a includes a condenser 12a, a water supply pump 13a, and a water supply valve 2.
2a and a waste heat recovery steam generator 10a are arranged, and a water supply pipe 11a located at the water supply valve 22a.
A bypass 25a having bypass valves 23a and 24a is provided so as to straddle the water supply valve 22a. Further, a main steam pipe 14a having an on-off valve _14a1 is provided between the waste heat recovery steam generator 10a and the steam turbine 5a, and this main steam pipe 14a has a main steam stop valve 15a and a steam control valve 15a. Valve 16a is attached in order. Furthermore, a bypass 18a equipped with a bypass valve 17a is connected and provided between the main steam pipe 14a on the upstream side of the main steam stop valve 15a and the condenser 12a, and the main steam pipe 14a is provided with a bypass 18a provided with a bypass valve 17a. Steam header 21 is switching valve 1
It is connected via a steam line 20a with 9a. Furthermore, both the bypass valves 23a and 2
A water supply header 2 is installed in the bypass 25a between the
6 is provided.

In this way, the first power generation unit based on the combined cycle that combines the gas turbine 3a and the steam turbine 5a is provided with second, third, fourth power generation units, etc. having the same configuration as the first power generation unit in parallel. It is being Therefore, the same components as the first power generation unit include the first power generation unit.
Instead of the symbol a for the power generating unit, the second power generating unit is designated by b, the third power generating unit is designated by c, and the fourth power generating unit is designated by d.

Thus, the steam headers 21 are connected to the main steam pipes 14b, 14c, 14d of the second power generation unit, the third power generation unit, and the fourth power generation unit. , 20d, and the water supply header 26 is connected to bypasses 25b, 25c, and 25d of the second, third, and fourth power generation units.

In addition, each of the waste heat recovery steam generators _10b , _10c , _10d of each of the above-mentioned power generation units, . 10b,1
The generation of steam by heat exchange at 0c and 10d can be adjusted as necessary. Further, each turbine shaft 6b of each of the above-mentioned power generation units, .
Each starting motor 7b, 7 is provided at one end of 6c, 6d.
c, 7d are connected via respective clutches 8b ₁ , 8c ₁ , 8d ₁ , and each gas turbine 3b , 3c , 3
Each rotating shaft 6 of each generator 4b, 4c, 4d provided between d and each steam turbine 5b, 5c, 5d
b ₁ , 6c ₁ , 6d ₁ are a pair of clutches 8b ₂ , 8
It is connected to each of the turbine shafts 6b, _6c , and 6d via b ₃ , 8c ₂ , 8c ₃ , 8d 2 , and 8d ₃ .

Hereinafter, the effects of the present invention will be explained.

For convenience of explanation, it is assumed that the first starting operation of the present invention is performed by the drive motor 7a of the first power generation unit. In this case, in advance, the switching valve 19a of the steam line 20a and the bypass valves 23a and 24a communicating with the water supply line 26 are fully closed.

As a result, when the starting motor 7a is driven, it is started based on the starting schedule shown in FIG. 2, and is raised to and maintained at the rated rotational speed and rated steam conditions. When the first power generation unit reaches the normal operating state at the rated rotational speed, the other second, third, fourth power generation units, etc. start up in order and gradually increase from small output power generation to high output power generation. raise.

That is, as described above, when the first power generation base unit reaches the rated rotational speed, the internal pressure of the first power generation unit 12a reaches the rated vacuum. Next, the main steam pipe 14b of the second power generation unit
Fully close the on-off valve _14b1 , and open the steam line 2.
0b switching valve 19b is fully opened. By fully opening the switching valve 19a of the steam header 21, the steam that has reached the rated steam condition in the first power generation unit is passed through the steam header 21 to the steam line 20b of the second power generation unit.
Rated steam is supplied up to the main steam stop valve 15b. By opening the main steam stop valve 15b and the steam control valve 16b, the second power generation unit is actually started and operated in the same manner as the first power generation unit. In addition,
In this case, without starting the starting motor 7b,
Can be started. In addition, the water supply header 2
The water supply of No. 6 is provided by each bypass valve 23b, 2 as necessary.
4b can be opened to supply water to the water supply pipe 11b.

In this way, the third and fourth power generation units,
Since steam from the first power generation unit and the second power generation unit described above can be supplied through the steam header 21, the steam from the steam header 21 is used to power the third and fourth power generation units on the steam turbines 5c and 5d. The power generation unit can be started.
Therefore, each power generation unit other than the first power generation unit, .
It can be started without using . In addition, each waste heat recovery steam generator 10a, 10b, 10
Each reheater 10a ₁ , 10 incorporated in c, 10d
b ₁ , 10c ₁ , 10d ₁ are each power generation unit,,
, when there is a shortage of generated steam, such as when the steam generator is started, and can be selectively activated to increase the amount of steam produced.

In particular, the present invention not only has the function of a power generation plant from a small capacity output to a large capacity output;
Various startups, operations, and stops can be performed as necessary.

That is, a plurality of power generation units,...
Not only can you start the power generation units in sequence, but you can also change the order and start them up.If any one of the above power generating units has a problem or requires periodic inspection, the steam header 21 or Any one of the reheaters 10a ₁ , 10b 1 , 10c ₁ , 10d ₁ of the waste heat recovery steam generators 10a, 10b, 10c, _10d that utilizes the water supply header 26 and is incorporated in each power generation unit, . On the other hand, each generator 4a, 4b,
4c, 4d clutches 8a ₂ , 8a ₃ , 8b ₂ , 8
b ₃ , 8c ₂ , 8c ₃ , 8d ₂ , 8d _{3 ,} etc. can be functionally operated to separately operate a gas turbine or a steam turbine.

On the other hand, for example, if the gas turbine 3a of the first power generation unit has a problem or undergoes periodic inspection,
When the steam turbine 5a of the first power generation unit is operable, the on-off valve _14a1 is closed and the other switching valve 19a is opened. On the other hand, the clutch _8a2 is released, thereby separating the gas turbine 3a. Thus, the steam turbine 5a and generator 4a of the first power generation unit can be operated independently by receiving steam from the steam header 21.

In this case, the steam header 21 is passed from the other power generation unit, and the switching valve 19a,
The steam flows into the steam turbine 5a through the steam stop valve 15a and the steam control valve 16a, where the steam turbine 5a
It can also be driven.

Note that the steam conditions flowing into the steam turbine 5a are the same as those for each gas turbine 5a, 5 of all power generation units.
Since the enthalpy is lower than when b, 5c, and 5d are in operation, in order to increase the enthalpy of steam and increase the efficiency of the power generation plant,
Waste heat recovery steam generator 10b of other power generation unit,
10c, 10d reheater 10b ₁ , 10c ₁ , 10
d ₁ increases the enthalpy of the steam and maintains the efficiency of the power generation unit. At this time, the water supply valves 22a, 22b, 22c, 22d
is closed, and the other bypass valves 23a, 24a, 2
3b, 24d, 23c, 24c, 23d, 24d
By opening the valve and opening the flow path of the water supply header 26, each water supply pipe 11a, 11b, 11c, 11d
The waste heat recovery steam generators 10a, 10b,
Water is supplied to 10c and 10d. Furthermore, the rotational speed of the steam turbine 5a is controlled by adjusting the opening degree of the steam control valve 16a using a speed governor _5a1 connected to the steam turbine 5a. Speed and load control of the steam turbine 5a is performed. Further, the steam that has done work in the steam turbine 5a is condensed by the condenser 12a, and this condensate is passed through the bypass valves 24a and 23a to the water supply pipe 25.
supplied to a. Further, the water supply is also sent to other water supply pipes 25b, 25c, and 25d through the water supply header 26.

As described above, according to the present invention, the gas turbine 3 includes the starting motors 7a, 7b, 7c, and 7d.
a, 3b, 3c, 3d and steam turbines 5a, 5
A plurality of power generation units 10a, 10b, 10c, .
10d, each reheater 10a ₁ , 10b ₁ , 10c ₁ , 1
0d ₁ is attached, and the above waste heat recovery steam generator 10a,
Each switching valve 1 connected to 10b, 10c, 10d
Each steam line 20a, 20b, 20c, 20d having 9a, 19b, 19c, 19d is connected to the steam header 21, and each of the above-mentioned power generation units,...
, each condenser 12a, 12b, 12c, 12
Water supply pumps 13a, 13b, 13 connected to d
c, 13d and water supply valves 22a, 22b, 22c,
Each water supply pipe 11a, 11b, 11 with 22d
Bypass valves 23a, 24b, 23 in c, 11d
Each bypass 25a, 25b, 25c, 25 with b, 24b, 23c, 24c, 23d, 24d
d is attached, and a water supply pipe 26 is connected to each bypass, so each power generation unit...
Steam can be smoothly supplied and received between the two, and each starting motor 7a, 7b, 7c, and 7d can be started independently, so that it can be used to generate power from small to large outputs. Not only can the power generation units be operated flexibly, but each power generation unit can also be operated selectively for maintenance and inspection. Furthermore, according to the present invention, the gas turbine and steam turbine of each power generation unit can be operated separately, so that the system can be operated functionally even in the event of a failure or maintenance inspection.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a conventional combined cycle power generation plant, FIG. 2 is a graph showing the start-up schedule of the power generation plant, and FIG. 3 is a system diagram of a combined cycle power generation plant according to the present invention. ,,,...power plant, 3a,3
b, 3c, 3d...gas turbine, 5a, 5b,
5c, 5d...Steam turbine, 7a, 7b, 7
c, 7d... Starting motor, 10a, 10b, 10
c, 10d...waste heat recovery steam generator, 10a ₁ , 1
0b ₁ , 10c ₁ , 10d ₁ ... Reheater, 12a, 1
2b, 12c, 12d...condenser, 21...steam header, 26...water supply header.

Claims (1)

[Claims] 1. A plurality of power generation units using a combined cycle combining a gas turbine and a steam turbine each equipped with a starting motor are provided in parallel, and each waste heat recovery steam generator incorporated in each power generation unit Each reheater is attached, each steam line having each switching valve connected to each of the above waste heat recovery steam generators is connected to a steam header, and a water supply pump is connected to each condenser of each above-mentioned power generation unit. A combined cycle power generation plant characterized in that each water supply pipe equipped with a water supply valve is provided with a bypass having each bypass valve, and a water supply header is connected to each bypass. 2. A patent characterized in that both clutches are provided at both ends of a rotating shaft of a generator provided between a gas turbine and a steam turbine of each power generation unit, and the two turbines are connected via these two clutches. A combined cycle power generation plant according to claim 1.