JPH02163402A - Compound electric power plant and its operation - Google Patents

Abstract

PURPOSE:To increase load down rate of an electric power plant overall by providing a means for bypassing all or a part of high-pressure steam to the lower stream side of a steam turbine. CONSTITUTION:At the time of load down, deviation between a load down requir ing signal 41 and a load output signal 45 of a generator 9 is read at a control device 40, and if the output in operation is larger than the required output, a contracting instruction 42 is sent to a fuel flow regulation valve 18. After that, when the opening degree reaches the allowable minimum degree set in advance by a signal 44 from an opening degree detector 39, an opening instruc tion 43 for opening a turbine bypass valve 19 is further sent. By this method opening degree of the turbine bypass valve 19 is controlled so that excessive steam from a waste heat recovering boiler 2 is directly bypassed to a condenser 15 and the load output from the generator 9 accords with the required output. As an existing turbine bypass valve can be utilized, and increase of load down rate can be contrived without installing any new equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combined power generation plant and a combined power generation plant in which the load reduction rate of one power generation plant as a whole is increased by controlling the loads of a gas turbine and a steam turbine. Regarding driving methods.

[Conventional technology]

Generally, a combined cycle power plant includes a gas turbine that is rotationally driven by combustion gas, an exhaust heat recovery boiler that generates high-pressure steam using exhaust gas from the gas turbine, and steam that is rotationally driven by the high-pressure steam from the exhaust heat recovery boiler. A turbine is installed.

In such a combined power generation plant, it is necessary to control the loads of the gas turbine and steam turbine according to fluctuations in power consumption. In conventional combined cycle power plants, only the load on the gas turbine is controlled by adjusting the fuel flow rate, and the load on the steam turbine is not particularly controlled.

Additionally, piping is installed to bypass the steam turbine.

A combined power generation plant in which a valve is installed in the middle of the piping has been proposed (for example, Japanese Patent Application Laid-Open No. 125705/1983). However, this piping is for exhausting excess steam during power plant startup, shutdown, load shedding, and tripping.
It is not intended to control steam turbines.

[Problem to be solved by the invention]

In the conventional technology, the combustion flow rate is adjusted.

Although it is easy to rapidly reduce the load on a gas turbine, it is difficult to rapidly reduce the load on a steam turbine. This is because the steam turbine uses high-pressure steam generated in the heat recovery steam generator. In other words, heat exchanger tubes for waste heat recovery boilers.

9 depending on the amount of heat stored in the header, drum, denitrification equipment, etc.
! This is because changes in live steam flow rate and temperature become smaller, and the response to the steam turbine becomes slower. For this reason, the load drop rate of the steam turbine becomes small, and the load drop rate of the combined power plant as a whole is about 5% at most. Further, it is impossible with the conventional technology to increase the load drop rate any further.

An object of the present invention is to provide a combined power generation plant and its operation that can prevent a delay in the response of a steam turbine to a load drop in response to a gas turbine load drop and increase the load drop rate of the power plant as a whole when the load is lowered. The purpose is to provide a method.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a gas turbine that is rotationally driven by combustion gas, an exhaust heat recovery boiler that generates high-pressure steam using the heat of exhaust gas from the gas turbine, and a gas turbine that is rotationally driven by the high-pressure steam. In a car-pressure type combined power generation plant comprising a steam turbine, a generator connected to the gas turbine and a rotating shaft of the steam turbine, all or part of the high-pressure steam is transferred to the natural gas turbine when the load is reduced. A means for escaping to the downstream side is provided.

The present invention also provides a gas turbine that is rotationally driven by combustion gas, an exhaust heat recovery boiler that generates high-pressure steam and low-pressure steam using the heat of exhaust gas from the gas turbine, and high-pressure steam that is rotationally driven by the high-pressure steam. A mixed-pressure combined power generation plant comprising a turbine, a low-pressure steam turbine rotationally driven by the low-pressure steam, and a generator connected to rotating shafts of the gas turbine, high-pressure steam turbine, and low-pressure steam turbine. Means is provided for releasing all or part of the high-pressure steam and low-pressure steam to the downstream side of the high-pressure steam turbine and the low-pressure steam turbine during descent.

The present invention also provides a gas turbine that is rotatably driven by combustion gas, a gas turbine that generates high-pressure steam using the heat of exhaust gas from the gas turbine, and an exhaust heat that generates reheated steam using a reheater provided inside the gas turbine. a recovery boiler, a high pressure steam turbine rotationally driven by the high pressure steam, a reheat steam turbine rotationally driven by the reheat steam,
In a reheat-type combined power generation plant comprising the gas turbine, a high-pressure steam turbine, and a generator connected to a rotating shaft of the reheat steam turbine, all or a part of the high-pressure steam is converted into the high-pressure steam during a load drop. Means is provided to allow the reheat steam to escape to the downstream side of the turbine, and also to allow a portion of the reheat steam to escape to the downstream side of the reheat steam turbine.

The present invention also provides a gas turbine rotationally driven by combustion gas, an exhaust heat recovery boiler generating high pressure steam using heat of exhaust gas from the gas turbine, a steam turbine rotationally driven by the high pressure steam, and a steam turbine rotatably driven by the high pressure steam. In a multi-shaft combined power plant including a generator connected to the rotating shaft of a gas turbine and a generator connected to the rotating shaft of the steam turbine, all or part of the high-pressure steam is The steam turbine is provided with means for releasing the steam to the downstream side of the steam turbine.

Furthermore, the present invention rotates a gas turbine with combustion gas, introduces the exhaust gas discharged from the gas turbine into an exhaust heat recovery boiler to generate high pressure steam, and rotates the steam turbine with the high pressure steam. , in the method of operating a combined power plant in which a generator is driven by the rotational force of the gas turbine and the steam turbine, when lowering the load, all or part of the high-pressure steam is directly released to the downstream side of the steam turbine. , the load on the steam turbine was quickly reduced.

[Effect]

According to the above configuration, in the case of a car pressure type combined power generation plant,
By letting all or a portion of the high-pressure steam escape to the downstream side of the steam turbine when the load decreases, the amount of high-pressure steam flowing into the steam turbine is reduced, and the load on the steam turbine can be rapidly reduced. At this time, by throttling the fuel flow rate, the load on the gas turbine is also rapidly reduced. The above also applies to multi-shaft combined power generation plants.

In addition, in the case of a mixed-pressure combined cycle power plant, when the load drops, all or part of the high-pressure steam and low-pressure steam is released to the downstream side of the high-pressure steam turbine and the low-pressure steam turbine, thereby increasing the load on the high-pressure steam turbine and the low-pressure steam turbine. can be rapidly reduced.

Furthermore, in the case of a reheat-type combined cycle power plant, by releasing all or part of the high-pressure steam to the downstream side of the high-pressure steam turbine when the load drops, the load on the high-pressure steam turbine is rapidly reduced, and the reheat steam is By venting all or part of it to the downstream side of the reheat steam turbine, it is possible to rapidly reduce the load on the reheat steam turbine.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

(First Embodiment) A first embodiment of the present invention is shown in FIG. This is a schematic diagram of a vehicle pressure type combined power generation plant. As shown in the figure,
Air 5 compressed by the gas turbine compressor 4 is sent to the combustor 6, where it is mixed with fuel 7 and combusted, resulting in high-temperature, high-pressure combustion gas. This combustion gas is introduced into the gas turbine 1, expands, and drives the gas turbine 1 to rotate. Gas turbine exhaust gas 1 that rotates the gas turbine 1
0 is sent to the exhaust heat recovery boiler 2 disposed on the downstream side, where it exchanges heat with the feed water 12.

Then, the thermal energy (sensible heat) held in the gas turbine exhaust gas 1o is recovered, and the gas turbine exhaust gas 1o is released into the atmosphere as a low-temperature gas 11.

Further, the feed water 12 supplied to the exhaust heat recovery boiler 2 becomes high-temperature, high-pressure steam 13 in the gas turbine exhaust gas 10 and is sent to the steam turbine 3 to activate the rotation of the steam turbine 3. Thereafter, the steam 13 becomes low-temperature, low-pressure steam 14, which undergoes heat exchange with seawater 16 in a condenser 15, and is condensed to become condensate and stored in the condenser 15. Furthermore, the pressure of the condensate is increased by a water supply pump 17 provided at the outlet of the condenser 15, and then supplied to the exhaust heat recovery boiler 2.

Further, the gas turbine 1 and the steam turbine 3, which have been driven one rotation, drive the generator 9 to obtain electric output.

In such a vehicle pressure type combined cycle power generation plant, when it is necessary to rapidly reduce the load, the flow rate of the fuel 7 is suppressed by throttling the fuel flow control valve 18, and the flow rate and temperature of the combustion gas 8 are reduced. As a result, the driving force of the gas turbine 1 decreases. Furthermore, as the flow rate and temperature of the gas turbine exhaust gas 1o from the gas turbine 1 also decreases, the sensible heat given to the exhaust heat recovery boiler 2 decreases, and the driving force of the steam turbine 3 also decreases due to the decrease in the amount, temperature, and pressure of generated steam. descend. However, there is a delay in response to the reduction in the driving force of the steam turbine 3. Therefore, in this embodiment, by opening the turbine bypass valve 19 when the load drops, all or part of the steam 13 flowing into the steam turbine 3 is bypassed directly to the condenser 15, thereby reducing the driving force of the steam turbine 3. . As a result, the load on the steam turbine 3 can be rapidly lowered, and the load lowering rate of the combined power plant as a whole can be increased more than before.

(Second Embodiment) A second embodiment of the present invention is shown in FIG. This is a schematic diagram of a mixed pressure combined cycle power generation plant. Only the differences from FIG. 1 will be explained.

A portion of the feed water 12 supplied to the exhaust heat recovery boiler 2 is boosted to high pressure by the transfer pump 21 provided in the exhaust heat recovery boiler 2, becomes high pressure steam 22, is sent to the high pressure steam turbine 24, and is turned into high pressure steam. The turbine 24 is driven to rotate. On the other hand, the feed water that does not pass through the transfer pump 21, that is, the feed water that is not pressurized, becomes low-pressure steam 23 and is sent to the low-pressure steam turbine 25, thereby driving the low-pressure steam turbine 25 to rotate. and,
The high-pressure steam 22 that rotates the high-pressure steam turbine 24 and the low-pressure steam 23 that rotates the low-pressure steam turbine 25 become low-temperature, low-pressure steam 14 and are sent to the condenser 15.

In such a mixed pressure combined cycle power plant, when it is necessary to rapidly reduce the load, the load on the gas turbine is reduced by throttling the fuel flow control valve 18, as in the first embodiment. Also, high pressure turbine bypass valve 2
6 and transfer all or part of the high pressure steam 22 to the condenser 15.
By bypassing the high pressure steam turbine 24, the load on the high pressure steam turbine 24 is reduced. At the same time, the low pressure turbine bypass valve 27
By opening the low-pressure steam turbine 23 and bypassing the low-pressure steam 23 to the condenser 15, the load on the low-pressure steam turbine 25 is reduced. In this way, it is possible to increase the load drop rate of the combined cycle power plant as a whole.

(Third Embodiment) A third embodiment of the present invention is shown in FIG. This is a schematic diagram of a reheat-type combined cycle power plant. Here, only the characteristic parts of this embodiment will be explained.

The high-pressure steam 28 from the waste heat recovery boiler 2 rotates the high-pressure steam turbine 29, and then becomes low-pressure, low-temperature steam 30, which is heated in the reheater 31 in the waste heat recovery boiler 2, and is converted into low-pressure, high-temperature steam 30. It becomes steam (reheated steam) 32. This reheated steam 3
2 flows into the reheat turbine 33 and drives the reheat turbine 33 to rotate.

In such a reheat type combined cycle power plant, when it is necessary to rapidly reduce the load, the load on the gas turbine is reduced by throttling the fuel flow control valve 18, as in the two embodiments described above. Descend. Furthermore, by opening the high-pressure turbine bypass valve 34 and bypassing the high-pressure steam 28 to the downstream side of the high-pressure steam turbine 29, the load on the high-pressure steam turbine 29 is reduced. In this case, in order to prevent the reheated steam temperature at the outlet of the reheater 31 from rising excessively, a desuperheater 35 is provided downstream of the high-pressure turbine bypass valve 34, and this desuperheater 35 is provided with a water supply. 12 is injected via control valve 36. Furthermore, the reheat turbine bypass valve 37
By opening the reheat turbine 32 and bypassing the reheat steam 32 to the condenser 15, the load on the reheat turbine 33 is reduced. In this way, it is possible to increase the load drop rate of the combined cycle power plant as a whole.

In the above three embodiments, each of the gas turbine device, the exhaust heat recovery boiler device, and the steam turbine device was configured with one unit, but the gas turbine device and the exhaust heat recovery boiler device were configured with multiple units, and the steam turbine device was configured with one unit. The present invention can also be applied to a multi-shaft combined power generation plant configured with a single power plant.

In other words, by directly bypassing the excess steam generated from the exhaust heat recovery boiler equipment to the downstream side of the steam turbine equipment, the load on the steam turbine equipment is lowered, and the load reduction rate of the combined cycle power plant as a whole is increased. is possible.

Gas turbines during load drops in combined cycle power plants
An example of a steam turbine load control device is shown in FIG. 4.

During load reduction, the control device 40 reads the deviation between the load reduction request signal 41 and the load output signal 45 of the generator 9, and if the output during operation is greater than the required output, the control device 40 controls the fuel flow control valve 18. A fuel flow rate reduction command 42 is issued. At that time, if the fuel flow control valve 18 of the gas turbine reaches a preset allowable minimum opening according to the opening signal 44 from the opening detector 39, the control device 40 further controls the turbine bypass valve 19 to open the turbine bypass valve 19. An opening command 43 for the bypass valve opening is issued. As a result, surplus steam from the exhaust heat recovery boiler 2 is bypassed, and the turbine bypass valve 19 is set so that the load output from the generator 9 matches the required output.
Controls the opening degree.

〔Effect of the invention〕

As explained above, according to the present invention, since the turbine bypass valve installed in the current combined cycle power plant is used, an increase in the load drop rate can be achieved without installing any new equipment. It is very economical.

[Brief explanation of the drawing]

Figure 1 is a schematic system diagram of a vehicle-pressure type combined power generation plant, Figure 2
The figure is a schematic system diagram of a mixed pressure type combined cycle power plant, Figure 3 is a schematic system diagram of a reheat type combined cycle plant, and Figure 4 is a schematic system diagram of a reheat type combined cycle power plant.
It is a schematic system diagram when a load control device is provided in the vehicle pressure type combined cycle power generation plant shown in the figure. 1... Gas turbine, 2... Exhaust heat recovery boiler, 3.
...Steam turbine, 4...Gas turbine compressor, 6.
... Combustor, 9... Generator, 13... High temperature and high pressure steam, 15... Condenser, 17... Water supply pump, 18...
・Fuel flow rate control valve, 19...Turbine bypass valve, 2
2... High pressure steam, 23... Low pressure steam, 24... High pressure steam turbine, 25... Low pressure steam turbine, 26...
...High pressure turbine bypass valve, 27...Low pressure turbine bypass valve, 28...High pressure steam, 29...High pressure steam turbine, 31... Reheater. 32... Reheat steam, 33... Reheat turbine, 34...
...High pressure turbine bypass valve, 37... Reheat turbine bypass valve, 40... Control device.

Claims (1)

[Claims] 1. A gas turbine rotationally driven by combustion gas;
An exhaust heat recovery boiler that generates high-pressure steam using the heat of exhaust gas from the gas turbine, a steam turbine rotationally driven by the high-pressure steam, and a generator connected to the rotating shafts of the gas turbine and the steam turbine. What is claimed is: 1. A single-pressure combined power generation plant comprising means for releasing all or part of the high-pressure steam to the downstream side of the steam turbine when the load drops. 2. In the combined power generation plant according to claim 1, the means comprises piping that communicates a condenser disposed downstream of the steam turbine and the exhaust heat recovery boiler via a turbine bypass valve. A combined power generation plant characterized by: 3. A gas turbine rotationally driven by combustion gas;
an exhaust heat recovery boiler that generates high-pressure steam and low-pressure steam using the heat of exhaust gas from the gas turbine; a high-pressure steam turbine rotationally driven by the high-pressure steam; a low-pressure steam turbine rotationally driven by the low-pressure steam; In a mixed-pressure combined power generation plant comprising a gas turbine, a high-pressure steam turbine, and a generator connected to rotating shafts of a low-pressure steam turbine, all or part of the high-pressure steam and low-pressure steam are converted into the high-pressure steam during load drop. A combined power generation plant characterized by providing means for escaping downstream of a turbine and a low-pressure steam turbine. 4. A gas turbine rotationally driven by combustion gas;
an exhaust heat recovery boiler that generates high-pressure steam using the heat of exhaust gas from the gas turbine and generates reheated steam using a reheater provided inside; a high-pressure steam turbine that is rotationally driven by the high-pressure steam; A reheat-type combined power generation plant comprising a reheat steam turbine rotationally driven by the reheat steam, and a generator connected to the rotating shaft of the gas turbine, high-pressure steam turbine, and reheat steam turbine, The present invention is characterized by providing means for releasing all or part of the high-pressure steam to the downstream side of the high-pressure steam turbine when the load decreases, and also releasing a part of the reheat steam to the downstream side of the reheat steam turbine. Combined power plant. 5. A gas turbine rotationally driven by combustion gas;
an exhaust heat recovery boiler that generates high-pressure steam using the heat of exhaust gas from the gas turbine; a steam turbine rotationally driven by the high-pressure steam; a generator connected to the rotating shaft of the gas turbine; A multi-shaft combined power generation plant comprising a generator connected to a rotating shaft, characterized in that a means is provided for releasing all or part of the high-pressure steam to the downstream side of the steam turbine when the load drops. A combined power generation plant. 6. A gas turbine is rotationally driven by the combustion gas, the exhaust gas discharged from the gas turbine is introduced into an exhaust heat recovery boiler to generate high-pressure steam, and the steam turbine is rotationally driven by the high-pressure steam, and the gas turbine is In the method of operating a combined power plant in which a generator is driven by the rotational force of a steam turbine, when the load is lowered, all or part of the high-pressure steam is directly released to the downstream side of the steam turbine. A method of operating a combined power generation plant characterized by rapidly lowering the load.