JPH07101081B2 - Steam turbine plant and its operating method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a steam turbine plant, and in particular, when the load sharply decreases, the steam generation amount is suppressed correspondingly to prevent the generation of surplus steam. And a method for operating the same.

[Conventional technology]

In today's steam turbine plants, there is a case where a sudden drop in the load or a load shedding is unavoidable due to a trip or the like of auxiliary machinery that constitutes the plant. When performing these operations, in the turbine plant, operations such as load drop or load cutoff can be rapidly performed by closing the valve installed in the drive steam system, but with this, in the steam generation plant Tries to follow a sudden decrease in load by narrowing down or shutting off fuel.

However, due to the influence of residual fuel, etc., the load responsiveness exceeds the allowable range and a load difference occurs with the turbine plant.
That is, the amount of steam generated by the steam generator exceeds the amount of steam required by the turbine, and surplus steam is generated. There is an increasing need for a method of operating a steam turbine plant that keeps the load responsiveness of the steam generating plant within an allowable range and does not generate surplus steam.

Next, with reference to FIG. 2, a problem when the load is suddenly reduced and the load is cut off in the conventional steam turbine plant will be specifically described.

In Fig. 2, the steam generated by the steam generator 1 is the main steam pipe.
Enter high pressure turbine 2 via 13. The steam that has worked in the high-pressure turbine 2 passes through the low-temperature reheat steam pipe 14, returns to the steam generator 1 again and is reheated, passes through the high-temperature reheat steam pipe 15, and works in the intermediate-pressure turbine 3 and the low-pressure turbine 4. . The work performed by the steam in each of the turbines 2, 3 and 4 is converted into electric energy in the generator 5. Also, the steam that has finished its work in each turbine 2, 3, 4 is reduced to water by the condenser 6, and is degassed by the condensate pump 7 via the condensate pipe 16 and the low-pressure feed water heater 8. The water is sent to the steam generator 9, and then returned to the steam generator 1 by the water supply pump 10 via the water supply pipe 17, the high-pressure first feed water heater 11, and the high-pressure second feed water heater 12.

When the steam turbine plant is operating normally, heat is exchanged with the feed water by the high temperature steam extracted from the turbines 2, 3 and 4 in the feed water heaters 8, 11 and 12 and the deaerator 9 in the above process. And heat the water supply.

[Problems to be Solved by the Invention]

The above is the outline of the configuration of the steam turbine plant. When the load is cut off in this steam turbine plant and the operation is shifted to the in-house independent operation, the generator 5 drives the amount of driving electricity of the auxiliary equipment installed in the steam turbine plant. Only the power is generated, that is, the island operation is continued. At this time, in the turbine side plant, the main steam valve 18 can be instantly narrowed down, and the amount of steam working in each turbine 2, 3, 4 can be instantaneously suppressed to an amount corresponding to the amount of electricity.

However, in the steam generator side plant, shut down the external heat source for converting the feed water into steam by narrowing down the fuel or shutting off the fuel, and reduce the generated steam amount to the steam amount required by the turbines 2, 3 and 4. However, the allowable range of maximum load drop rate (maximum load response) even if the external heat source is turned off due to the effect of the internal fuel heat quantity due to the residual fuel in the steam generator 1, the retained water, the retained heat of the structure, etc. Is limited to the attenuation rate of the internally retained heat quantity remaining inside the steam generator 1.

Here, a large difference occurs in the load drop rates of the steam generator 1 and the turbines 2, 3, and 4. That is, excess steam is generated because the steam generation device 1 generates steam in excess of the steam amount required by the turbines 2, 3, and 4. The generated excess steam loses its place of travel, causes a boosting phenomenon inside the main steam pipe 13, and a safety valve installed in the steam system of the steam generator 1 opens to release a large amount of steam with high heat energy into the atmosphere. In the worst case, the kinetic energy (dynamic pressure) of the steam staying inside the main steam pipe 13 may cause the main steam pipe 13 and the steam generator 1 to burst. All of these problems are caused by the fact that the surplus steam generated from the steam generator 1 cannot be suppressed.

An object of the present invention is to provide a steam turbine plant capable of preventing generation of excess steam from a steam generator when the load of the steam turbine is suddenly reduced or the load is cut off, and an operating method thereof. .

[Means for Solving the Problems]

The above-mentioned object is to drive the turbine with the steam generated by the steam generator, and to condense the steam after the turbine is driven to obtain the feed water, which is supplied from the feed pump to the steam generator via the feed water heater. In the turbine plant operating method, when performing a sudden load reduction or load shedding operation, a part of the feed water before being heated by the feed water heater is bypassed to a bypass passage confluence point provided on the downstream side of the feed water heater. While supplying to the steam generator, a part of the feed water supplied from the feed water heater to the steam generator is taken from the upstream side of the bypass passage confluence point and returned to the upstream side of the water supply pump, This is achieved by suppressing the amount of steam generated by the steam generator.

The above object is also to provide a turbine that uses the steam generated in the steam generator, and a water supply pump that supplies the water supplied by condensing the steam discharged from the turbine to the steam generator through a water heater. A first bypass pipe for returning a part of the feed water on the outlet side of the feed water heater to the upstream side of the feed water pump, and a first opening / closing valve for opening and closing the first bypass pipe. A second bypass pipe for supplying a part of the supply water discharged from the water supply pump to a downstream side of a water intake point of the first bypass pipe, and a second opening / closing valve for opening / closing the second bypass pipe. It is achieved by having it.

[Action]

The present invention focuses on how to prevent the above-mentioned surplus steam from being generated, and the solution will be described below.

First, in order to accelerate the attenuation of the internal heat quantity retained inside the steam generator, which is a surplus steam generator from the steam generator, it is necessary to lower the temperature of the feed water supplied to the steam generator. Is the most effective and easy way to achieve.

The steam generation amount F is calculated by the following Equation 1.

F = Q / (T ₁ −T ₂ ) ... Equation 1 where Q: internal heat of the steam generator T ₁ : steam temperature generated from the steam generator T ₂ : feed water temperature supplied to the steam generator F: at generation amount of steam above equation 1 from the steam generator, since the internal heat held Q and generating steam temperature T1 of the steam generator is unchanged, by reducing the feed water temperature T ₂ is supplied to the steam generator, steam generator When the temperature rise in the apparatus is increased, the generated steam amount F can be reduced, and the generation of surplus steam can be suppressed. That is, it is possible to suppress the generation of surplus steam by supplying the feed water before being heated by the feed water heater to the steam generator through the second bypass pipe.

Second, instead of supplying the entire amount of water supply to the steam generator from the water supply pump, a part of the water is circulated in the turbine side plant to reduce the amount of water supply. This suppresses the flow of water and steam circulating in the steam turbine plant, thereby reducing the kinetic energy in the main steam pipe, which is the above-mentioned problem, and ensuring safety. By reducing the kinetic energy in this way, it is possible to suppress the generation of excess steam. That is, through the first bypass pipe,
It is possible to suppress the generation of surplus steam by returning a part of the supply water before it is supplied to the steam generator to the water supply pump.

〔Example〕

FIG. 1 is a system diagram of an example of a steam turbine plant configured to apply the operating method of the present invention.

In order to lower the feed water temperature to be supplied to the steam generator 1, the second high-pressure first feed water heater 11 and the high-pressure second feed water heater 12 are bypassed from the outlet of the water feed pump 10 to supply water to the steam generator 1. A bypass pipe 21 (the first bypass pipe will be described later) and a second opening / closing valve 25 (the first opening / closing valve will be described later) that opens and closes the second bypass pipe 21 are installed. This is the high pressure first feed water heater when the load is suddenly reduced and the load is cut off in the steam turbine plant.
11, The heating steam of the high-pressure second feed water heater 12 suddenly decreases or disappears at all, but inside the high-pressure first feed water heater 11, the high-pressure second feed water heater 12 and the water pipe 17 at their outlet,
Hot water pump that contains hot water and is not heated
The hot water is supplied to the steam generator 1 by the time the feed water at the 10th outlet is supplied to the steam generator 1, and the attenuation of the internal heat quantity Q of the steam generator 1 is not promoted.

Therefore, when performing these sudden load reduction and load shedding operations, the second
The on-off valve 25 is opened, unheated feed water at the outlet of the water supply pump 10 is supplied to the steam generator 1 to promote the decay of the internal heat quantity of the steam generator 1, and the surplus steam generated from the steam generator 1 is removed. It becomes possible to suppress. Further, in this case, by narrowing or shutting off the water supply valve 20 which is a valve installed on the outlet side of the high-pressure second water supply heater 12,
By reducing or interrupting the high-temperature feed water supplied to the steam generator 1, the internal heat quantity Q of the steam generator 1 can be more effectively attenuated, and the excess steam generated from the steam generator 1 can be reduced. It is superior to restraint.

Next, as a device and an operating method for implementing the above-mentioned second solution, a part of the high-temperature feed water supplied to the steam generator 1 is branched from the water supply pipe 17. In this figure, the high pressure second
A first bypass pipe 22 that returns from the outlet of the feed water heater 12 to the deaerator 9 and a first opening / closing valve that opens and closes the first bypass pipe 22.
Install 26. This circulates a part of the high temperature feed water supplied to the steam generator 1 between the deaerator 9, the water feed pump 10, the high pressure first feed water heater 11, and the high pressure second feed water heater 12, and the circulation thereof. The amount of water supplied to the steam generator 1 is reduced by the amount of the supplied water. That is, when the load is suddenly reduced or the load is shut off, by opening the first on-off valve 26, a part of the high-temperature feed water supplied to the steam generator 1 circulates in the turbine-side plant. Just the amount of water,
It is possible to reduce the amount of water supplied to the steam generator 1 and suppress the surplus steam generated from the steam generator 1.

Further, in the embodiment shown in FIG. 1, in order to use the surplus steam generated from the steam generator 1, the auxiliary steam used in the turbine side plant is supplied from the main steam pipe 13 or the steam line inside the steam generator 1. Take it out. In this figure,
An auxiliary steam pipe 23 and an auxiliary steam valve 27 for supplying steam from the inside of the steam generator 1 to the high-pressure second feed water heater 12 are installed. If necessary, an auxiliary steam header can be installed in the middle of an auxiliary steam pipe connecting the steam generator 1 and the high-pressure second feed water heater 12. When using these devices, the auxiliary steam valve 27 is opened when the load is suddenly reduced or the load is cut off, and the surplus steam generated from the steam generator 1 is made to flow into the high-pressure second feed water heater 12 as auxiliary steam. . Then, the auxiliary steam is converted into drain inside the high pressure second feed water heater 12. The drain is collected in the deaerator 9 or the condenser 6 via the drain pipe 24 and the drain valve 28. That is,
By using the surplus steam generated from the steam generator 1 as auxiliary steam, the steam to be surplus becomes necessary steam, and the surplus steam generated from the steam generator 1 can be suppressed.

Furthermore, when the steam generator 1 is a thermal power plant that uses crude oil, coal, etc. as fuel, the steam generated from the steam generator 1 is taken out as auxiliary steam in the steam generator plant. In FIG. 1, the steam is supplied from the inside of the steam generator 1 as soot blower steam of the steam generator 1.
In addition, an auxiliary steam header can be installed during this time. This makes it possible to suppress excess steam.

When the load is suddenly reduced or the load is cut off in the steam turbine plant of FIG. 1, the second opening / closing valve 25, the first opening / closing valve 26, and the auxiliary steam valve 27 are opened. Further, the water supply valve 20 is closed contrary to the above-mentioned valve. As a result, the temperature of the feed water supplied to the steam generator 1 can be reduced and at the same time the flow rate of the feed water can be reduced and the surplus steam can be effectively utilized, the surplus steam generated from the steam generator 1 can be suppressed, and the load on the steam generator 1 can be lowered. It is also possible to keep the descent rate during operation within the allowable range.

The effects are described below with reference to the attached charts.

In FIG. 3, the horizontal axis represents time t and the vertical axis represents the steam generator 1.
The flow rate of water supplied to the turbine and the amount of circulating water circulating in the turbine side plant are calculated. Further, t _{0 on the} time axis indicates the load drop start timing, and t ₂ indicates the load drop end time. And
A solid curve 42 is a feedwater flow rate characteristic curve to be supplied to the steam generator 1 according to the conventional technique, and a broken line curve is a feedwater flow rate characteristic curve 43 to be supplied to the steam generator 1 according to the present invention and in the turbine side plant. It is a circulating water amount characteristic curve 44. Here, since the discharge flow rate of the feed water pump 10 and the feed water flow rate are almost the same, the feed water supplied from the feed water pump 10 to the steam generator 1 by the start of the load lowering operation as in the present invention and the turbine side plant. When it is divided into circulating water circulating in the inside, as can be seen by comparing the feed water flow rate characteristic curves 42 and 43 between the feed water flow rate according to the prior art and the feed water flow rate according to the present invention, the case of the present invention produces more steam. The water supply flow rate supplied to the device 1 is small.

FIG. 4 is a chart showing a characteristic curve of the steam generator 1, in which the horizontal axis shows times t, t ₀ , t ₂ similar to those in FIG. 3, and the vertical axis shows the feed water flow rate characteristic curve (from the bottom). This curve is the same as that shown in Fig. 3, but is also referred to in this figure to explain the characteristics of the steam generator 1.), the feed water temperature characteristic curve, the heat load characteristic curve, and the generation A steam flow characteristic curve is shown. Further, as in FIG. 3, the solid lines are characteristic curves 42, 45, 4 obtained by the conventional technique.
7, 49, and the broken lines are the respective characteristic curves 43, 46, 48, 50 obtained in this embodiment. In this example, the reduction of the feed water flow rate supplied to the steam generator 1 is as described above, and will be omitted.

Regarding the water supply temperature, in the conventional technology, the water supply temperature characteristic curve
As shown by 45, after all of the accumulated water inside the high pressure second feed water heater 12 and the high temperature water accumulated inside the water supply pipe 17 at the outlet of the high pressure second feed water heater 12 are supplied to the steam generator 1. According to the present invention, whereas the feed water temperature drops, the feed water at the outlet of the feed water pump 10, that is, before passing through the high-pressure first feed water heater 11 and the high-pressure second feed water heater 12 for heating is started according to the present invention. Since the supply water is directly supplied to the steam generator 1, the supply water temperature can be instantly lowered. Due to the characteristics of the feed water flow rate and the characteristics of the feed water temperature, the heat load characteristic of the steam generator is reduced in a manner almost proportional to the feed water flow rate as in the heat load characteristic curve 47 in the prior art. When the load lowering operation is started, the temperature rises once as shown in the heat load characteristic curve 48. This is because, as described above, since the generated steam temperature is constant, the supply water temperature lowers, so that the steam generator 1 needs to change the supplied water into steam and increase the amount of heat necessary for further heating. is there. That is, the heat load on the steam generator increases rapidly.

Due to these phenomena, the amount of steam generated from the steam generator 1 is calculated by the generated steam flow rate characteristic curves 49, 50 shown at the top of the figure.
It becomes like.

First, in the prior art, as shown in the generated steam flow rate characteristic curve 49, it decreases almost in proportion to the feedwater flow rate characteristic curve 42, whereas according to the present embodiment, the heat load of the steam generator 1 is reduced due to the start of the load drop. Since the temperature rises as shown by the heat load characteristic curve 48, if the generated steam temperature is kept constant, the generated steam flow rate can be rapidly reduced as shown by the characteristic curve 50. This is established by the function formula of the generated steam amount as shown in the above-mentioned formula 1. In addition, by using a part of this rapidly reduced amount of generated steam as auxiliary steam to the high-pressure second feed water heater 12, the effect of further suppressing the excess steam generated from the steam generator 1 can be sufficiently obtained.

As described above, according to the present embodiment, during the load lowering operation of the steam turbine plant, particularly during the operations such as the sudden load reduction and load shedding, the load is reduced in both the turbine and the steam generator to eliminate the load imbalance and to generate steam. It is possible to suppress the excess steam from the equipment.

Further, in this embodiment, a part of the feed water supplied to the steam generator 1 is passed through the high pressure first feed water heater 11 and the high pressure second feed water heater 12 and circulated to the deaerator 9. At this time, , The auxiliary steam is caused to flow into the high-pressure second feed water heater 12 to exchange heat with the circulating water, and the circulating water becomes heated water and the deaerator 9
Return to. Further, the auxiliary steam that has exchanged heat with the circulating water is drained and collected in the deaerator 9. These circulating water and drain have the following effects.

A water supply pump 10 for supplying water to the steam generator 1 to configure a steam turbine plant, and dissolved in the water supply.
A deaerator 9 for deaerating O ₂ is installed, but when the steam turbine plant performs load lowering operation, the heating source of the deaerator 9 is lost and the water stored inside the deaerator 9 is deaerated. The condensate flowing into the vessel 9 lowers the temperature, and further the deaerator 9
Will also reduce the pressure of. This phenomenon is caused by the water pump 10
Since it becomes impossible to secure the pushing pressure of the water supply pump 10 and the water supply pump 10 is tripped, it becomes impossible to supply the water supply to the steam generator 1, and there is a high risk of a plant trip, so it is necessary to suppress the temperature drop of the deaerator 9. is there. For this reason, in addition to the condensate for lowering the stored water temperature inside the deaerator 9, the circulating water and the drain flow into the deaerator 9 that has lost the heating source. The effect of suppressing the temperature drop and the pressure drop and making it possible to secure the pushing pressure of the water supply pump 10 at a sufficient value is obtained. This phenomenon will be described below with reference to FIG.

The horizontal axis in this figure shows the times t, t ₀ , and t ₂ similar to those in FIGS. 3 and 4. The vertical axis shows pressure and temperature. Further, the characteristic curve according to the conventional technique is shown by a solid line, and the characteristic curve obtained in this embodiment is shown by a broken line.

In the characteristic curve of this figure, in the conventional technique, the stored water temperature inside the deaerator 9 drops like a stored water temperature characteristic curve 57. Then, the pressure of the deaerator 9 becomes the deaerator pressure characteristic curve.
It descends like 51. Further, the required pushing pressure of the water feed pump 10 drops like the feed water pump pushing pressure characteristic curve 53. Then, the effective pushing pressure of the water feed pump 10 drops like a water feed pump effective pushing pressure characteristic curve 55. Comparing these characteristic curves 53 and 55 from time t ₂ onward, it can be seen that the difference is very small. If this pressure difference is too small or reverses, the pressure switch installed to protect the water supply pump 10 detects a low push-in pressure of the water supply pump 10 and trips the water supply pump 10, causing steam generation. There is a risk that the equipment 1 cannot be supplied and a plant trip occurs. In the present embodiment, as described above, the temperature of the stored water in the deaerator 9 is suppressed from decreasing by causing the heated circulating water and the drain to flow into the deaerator 9. As a result, the stored water temperature of the deaerator 9 is lowered as shown by the stored water temperature characteristic curve 58,
The pressure of the deaerator 9 becomes like the deaerator pressure characteristic curve 52, and the required pushing pressure and the effective pushing pressure of the water feed pump 10 are the feed water pump required pushing pressure characteristic curve 54 and the water feed pump effective pushing pressure characteristic curve 56, respectively. As a result, the respective characteristic drop rates are slower than those of the prior art.
The difference between the characteristic curves 54 and 56 is also the characteristic curve of the conventional technology.
It becomes larger than the difference between 53 and 55, and the effect of sufficiently securing the pushing pressure required to operate the water supply pump 10 is obtained.

Further, regarding the use of the auxiliary steam in the steam generating plant, by using the auxiliary steam as the steam for the stove blower of the steam generating apparatus 1, a cooling effect of the heater installed in the steam generating apparatus 1 is brought about. That is, the steam generator 1
In the case of a thermal power plant that uses crude oil or coal as the fuel for
Although the water supplied to the steam generator 1 is changed to steam by the heat energy of the waste gas of the fuel burned in the steam generator 1, the heat energy of the exhaust gas is absorbed when the water is steamed. The temperature of the exhaust gas is lowered, the steam generator 1 changes the feed water into steam, and at the same time, it also performs the cooling action of lowering the temperature of the combustion exhaust gas entering the heater. As a result, in the steam turbine plant, when a sudden load reduction operation such as load shedding is performed, the water supply in the steam generator 1 and the flow of steam are stopped, so that the one that lowers the combustion exhaust gas temperature of the steam generator 1 is lost, The heater may overheat. In order to avoid this phenomenon, auxiliary steam is used in the steam generation plant (as soot blower steam in this example) to obtain an effect of suppressing excess steam generated from the steam generation device 1 and to be provided in the steam generation device 1. It also makes it possible to obtain the cooling effect of the heater at the same time.

For the same purpose as the present invention (treatment of surplus steam during load lowering operation), as shown in FIG.
9, high pressure bypass pipe 35, high pressure bypass spray pipe 33, high pressure bypass spray valve 38, low pressure bypass pipe 30, low pressure bypass valve
A turbine bypass device provided with 36, desuperheater 41, low pressure bypass spray pipe 34, low pressure bypass spray valve 39, check valve 37, etc. is also used, but this device (Fig. 6) suppresses excess steam. Instead, the processing is performed so as not to cause a problem in the steam turbine plant. In this steam turbine plant (Fig. 6), the entire amount of feed water supplied to the steam generator 1 is passed through the high pressure first and second feed water heaters 11 and 12, and the method of the present invention is applied to the operation of this plant. Then, the effect of preventing the generation of excess steam becomes even more complete.

The characteristics of the high-pressure second feed water heater 12 and its surroundings of the steam turbine plant with turbine bypass will be described below with reference to FIG. In FIG. 7, the horizontal axis represents time t, t ₀ , t ₂ (this is the same as those in FIGS. 3, 4, and 5), and the vertical axis represents from the bottom. Feed water flow rate, internal pressure of the high-pressure second feed water heater 12, steam pressure of the same feed water heater 12, inlet / outlet feed water temperature of the high-pressure second feed water heater 12, high-pressure second
The amount of heating steam of the feed water heater 12 is taken. Looking at the point of t ₀ at which the load lowering operation is started, the heating steam pressure of the high-pressure second feed water heater 12 rapidly rises as shown by a characteristic curve 60. As a result, the internal pressure of the feed water heater 12 also rises as indicated by the characteristic curve 61. Due to this pressure increase phenomenon, the outlet feed water temperature of the feed water heater 12, that is, the steam generator 1
The water supply temperature to the temperature rises like the characteristic curve 45. Also,
High-pressure first feed water heater installed upstream of the feed water heater 12
Since 11 loses heating steam, the outlet of the high-pressure first feed water heater 11, that is, the inlet of the high-pressure second feed water heater 12, the feed water temperature decreases as shown by the characteristic curve 62, and the feed water at the inlet and outlet of the high-pressure second feed water heater 12 The temperature difference increases, and the amount of heated steam that exchanges heat with the supplied water increases as shown by the characteristic curve 63. The problem caused by this will be described with reference to FIG.

The horizontal axis in FIG. 8 is the same as in FIGS. 3, 4, 5, and 7. From the bottom, the vertical axis represents the high-pressure second feed water heater 12 heating steam flow rate characteristic, the kinetic energy of the feed water heater 12 heating steam, and the valve opening degree of the drain valve 28 of the same feed water heater 12. As described above, at the load lowering operation start point t _{0 of the} present plant, the heating steam flow rate of the high pressure second feed water heater 12 increases as shown by the characteristic curve 63. As a result, the kinetic energy of the heated steam increases as shown by the characteristic curve 65. Further, the increase in the amount of heating steam means the increase in the amount of drain of the feed water heater 12. For this reason, the valve opening degree of the drain valve 28 is set to the valve opening characteristic 67 of the drain valve 28 in order to discharge a large amount of drain.
It becomes big like. The first problem with these phenomena is that the high-pressure second feed water heater 12
Must be over-designed. Secondly, the capacity of the drain valve 28 must be increased in order to discharge a large amount of drain. If the capacity of the drain valve 28 is small, drain discharge failure occurs, and the high pressure second feed water heater 12
The water level rises and the drain flows back to the steam system, and in the worst case, the drain flows back to the turbine, causing water induction. Normally, a device for preventing this water induction is installed, but this device is a high pressure second feed water heater.
There are cases in which the turbine trip may be operated due to the high water level of 12 and the operation of the steam turbine plant may be forcibly stopped. 6th which had such a defect
By applying the operating method of the present invention to the steam turbine plant shown in the figure, since the amount of water to be supplied to the high-pressure first feed water heater 11 and the high-pressure second feed water heater 12 is reduced as described above, the high-pressure second feed water is reduced. The heater 12 heating steam amount is reduced, and the individual characteristics are smaller than the conventional characteristic curves 63, 65, 67 for any of the characteristic curves as shown by curves 64, 66, 68.
The problems described above are resolved.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, when the load of a steam turbine is rapidly reduced, or when a load is interrupted | blocked, it has the outstanding practical effect of being able to prevent generating a surplus steam from a steam generator, and a steam turbine plant. It greatly contributes to the improvement of the thermal efficiency and the ensuring of safety.

[Brief description of drawings]

FIG. 1 is a system diagram of an example of a steam turbine plant configured to apply the operation method of the present invention, and FIG. 2 is a system diagram of an example of a steam turbine plant according to a conventional technique.
Fig. 3 is a feed water flow rate characteristic chart, Fig. 4 is a steam generator operating characteristic chart, Fig. 5 is a deaerator surrounding characteristic chart, Fig. 6 is a system diagram of a steam turbine plant with a turbine bypass device, and Fig. 7 is FIG. 8 is a characteristic chart of the operation around the high-pressure feed water heater of the steam turbine plant with a turbine bypass device, and FIG. 8 is a characteristic chart of the heating steam of the high-pressure feed water heater and the drain valve. 1 ... Steam generator, 2 ... High pressure turbine, 3 ... Medium pressure turbine, 4 ... Low pressure turbine, 5 ... Generator, 6 ...
Condenser, 7 ... Condensate pump, 8 ... Low-pressure feed water heater, 9
...... Deaerator, 10 …… Water supply pump, 11 …… High pressure first feed water heater, 12 …… High pressure second water feed heater, 13 …… Main steam pipe, 14
...... Low temperature reheat steam pipe, 15 ...... High temperature reheat steam pipe, 16 ...... Condensation pipe, 17 …… Water supply pipe, 18 …… Main steam valve, 19 …… Reheat steam valve, 20 …… Water supply valve, 21 …… Second bypass pipe, 22 …… First bypass pipe, 23 …… Auxiliary steam pipe, 24 …… Drain pipe,
25 …… second opening / closing valve, 26 …… first opening / closing valve, 27 …… auxiliary steam valve, 28 …… drain valve, 29 …… high pressure bypass pipe, 30 …… low pressure bypass pipe, 31 …… bleed pipe, 32 …… Deaerator heating steam pipe, 33 …… High pressure bypass spray pipe, 34 …… Low pressure bypass spray pipe, 35 …… High pressure bypass valve, 36 …… Low pressure bypass valve, 37 …… Check valve, 38 …… High pressure Bypass spray valve, 39 …… Low pressure bypass spray valve, 40 …… Deaerator heating steam valve, 41 …… Desuperheater, 42,43 …… Supply water flow characteristic curve, 44 …… Circulating flow characteristic curve, 45,46 ...... Supply water temperature characteristic curve, 47,48 ...... Heat load characteristic curve, 49,50 …… Generated steam flow characteristic curve, 51,52 …… Deaerator pressure characteristic curve, 53,54 …… Water supply pump required pushing pressure Characteristic curve, 55,
56 …… Water pump effective pushing pressure characteristic curve, 57,58 ……
Storage water temperature characteristic curve, 60 …… Low temperature reheat steam pipe pressure characteristic curve, 61 …… High pressure second feed water heater pressure characteristic curve, 62…
… High pressure second feed water heater inlet feed water temperature characteristic curve, 63, 64
...... High-pressure second feed water heater heating steam flow rate characteristic curve, 65,6
6 …… High pressure second feed water heater heating steam kinetic energy characteristic curve, 67,68 …… Drain valve opening characteristic curve.

Claims (3)

[Claims] 1. A turbine is driven by steam generated by a steam generator, and the feed water obtained by condensing the steam after driving the turbine is supplied from a feed pump to the steam generator via a feed heater. In a method of operating a steam turbine plant, when performing a load reduction or load shedding operation, a part of the feed water before being heated by the feed water heater is provided at a junction of a bypass passage provided on the downstream side of the feed water heater. While bypassing and supplying to the steam generator, part of the supply water supplied to the steam generator from the feed water heater is taken from the upstream side of the bypass passage confluence and returned to the upstream side of the water supply pump. A method for operating a steam turbine plant, characterized in that the amount of steam generated by the steam generator is suppressed. 2. A turbine that uses steam generated by a steam generator, and a feed water pump that supplies the water discharged by condensing the steam discharged from the turbine to the steam generator through a feed water heater. A first bypass pipe for returning a part of the feed water on the outlet side of the feed water heater to the upstream side of the feed water pump;
A first on-off valve for opening and closing the bypass pipe, a second bypass pipe for supplying a part of the feed water discharged from the water feed pump to a downstream side from a water intake point of the first bypass pipe, and the second A steam turbine plant, comprising: a second opening / closing valve for opening / closing a bypass pipe. 3. The steam turbine plant according to claim 2, wherein a deaerator for deaerating the condensate is provided on the upstream side of the feed water pump, and feed water on the outlet side of the feed water heater is provided. A steam turbine plant, wherein a first bypass pipe for returning a part is connected to the deaerator.