JP2015017588A - Protection device of steam turbine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a flashback phenomenon and a water induction without requiring various valves, such as a check valve, a gate valve, and a control valve, and a control unit.SOLUTION: A protection device of a steam turbine system includes a steam turbine 1, a steam condenser 2, a feed water heater 3, and an extraction steam pipe 4. A communication tube 5 with a U-shaped tube is connected to the steam condenser 2 and the extraction steam pipe 4. In the communication pipe 5, a free water surface is formed which has a water head a corresponding to the pressure in the steam condenser 2 and the pressure in the extraction steam pipe 4.

Description

  The present invention relates to a protection device for a steam turbine system including a device for preventing a flashback phenomenon, water induction, and the like.

In a nuclear power plant or a thermal power plant, a condenser is installed to condense exhaust steam, which has been expanded by a steam turbine, by cooling, and a water-cooled type is used in the condenser to cool the exhaust steam. Heat transfer tubes are installed. Further, as shown in FIG. 10, a part of the steam flowing through the steam turbine 1 is extracted, and this extracted steam S is used as a heating source for the feed water heater 3 installed in the condenser 2 from the viewpoint of the arrangement of the power plant. There are some which are supplied through the extraction pipe 4. In the feed water heater 3 performs condensate or feedwater heat exchange extraction steam S is through heat transfer tubes 3 ₁ in the feed water heater 3, extraction steam deprived of heat by the condensate or feedwater condenses and drain ( Retained water) 3 ₂ is stored in the feed water heater 3. During normal operation, drain discharge is controlled by a drain valve (not shown) so that the water level in the feed water heater 3 is maintained at a predetermined position.

  In a nuclear power plant or thermal power plant, when the load is shut off during normal operation, or when a steam generator such as a nuclear reactor or a boiler is stopped, the amount of steam introduced into the steam turbine 1 is drastically reduced. The internal pressure of the steam turbine 1 is reduced. For this reason, the pressure inside the extraction pipe 4 and the pressure inside the feed water heater 3 connected to the extraction pipe 4 may decrease.

Drain 3 ₂ in the feed water heater 3 because of saturated water corresponding to the feed water heater 3 inside pressure during normal operation, the pressure drop occurs drain is flash boiled (flash), flash steam generated is the extraction pipe A flashback phenomenon may occur where the steam flows back into the steam turbine 1 and flows into the steam turbine 1 to increase the rotational speed of the steam turbine 1.
When the flashback phenomenon occurs, an excessive force is applied to the moving blades and stationary blades of the steam turbine 1, causing damage and breakage of these turbine blades.

  Conventionally, in order to prevent a flashback phenomenon, a check valve is installed in the extraction pipe 4 for the purpose of preventing backflow steam, or an intermediate part of the extraction pipe 4 connecting the steam turbine 1 and the feed water heater 3 is opened and closed. Is connected to the condenser 2 through a communication pipe having a flow rate, and when it is detected that the internal pressure of the steam turbine 1 is lower than the steam pressure of the drain inside the feed water heater 3, the open / close valve in the closed state is opened. There are inventions that switch to the open state to prevent drain steam from escaping into the condenser 2 and entering the steam turbine 1.

Further, when an abnormality such as a case where heat transfer tubes 3 ₁ in the feed water heater 3 has been damaged during power plant operation occurs, there is a case where drainage 3 ₂ in the feed water heater 3 rises above a predetermined level. Condensate 3 ₂ in the feed water heater 3 is increased, the drain 3 ₂ feed heaters 3 flows back to the extraction pipe 4, may be water induction occurs flowing into the worst case the steam turbine 1. If water flows into the rotating steam turbine 1 by water induction, it causes destruction and damage of the turbine internal structure.

To prevent the occurrence of the water induction, in addition to the drain discharge line to be used as a method of lowering elevated drain 3 ₂ level during normal operation, providing the emergency drain discharge line invention and, feedwater heaters and steam turbine 1 A shutoff valve is provided in the middle of the bleed pipe 4 that connects to the drainage pipe 3, and a drain pot is provided downstream of the shutoff valve. When the water level of the drain pot exceeds a certain value, the shutoff valve is closed and the drain 3 ₂ There invention the drainage valve of the downstream drain pot is prevented from flowing into the steam turbine 1 and to switch from a closed state to an open state, and further, the drain 3 ₂ exceeds a predetermined water level in the feed water heater 3 And the like that overflow through the U-shaped tube and are discharged to the condenser 2.

JP 2001-193416 A JP 2003-184511 A JP 2010-223105 A JP 7-174304 A JP 2003-193807 A Japanese Examined Patent Publication No. 63-24206

From the viewpoint of the arrangement of the power plant, as shown in FIG. 10, the extraction pipe 4 is directly fed into the condenser 2 without providing an extraction check valve in the middle of the extraction pipe 4 connected to the low pressure stage of the steam turbine 1. for the to be connected to a heater 3 arrangement, a drain 3 ₂ energy in the feed water heater 3 is low, it is suitable for power plant steam energy backflow small Flashback, large power plants with the reduction, the drain 3 ₂ in the feed water heater 3 is increased, which may adversely affect the steam turbine 1 steam amount of backflow during flashback is increased. For this reason, it can be said that the configuration of FIG. 10 is not suitable for a large-capacity power plant.

  In addition, in the case where the extraction pipe 4 is connected to the feed water heater 3 in the condenser 2 as shown in FIG. 10, if an extraction check valve or a gate valve is to be installed in the extraction pipe 4, maintenance of those valves is performed. For inspection and inspection, it is necessary to perform piping so that the connection portion of the extraction pipe 4 with the valve is pulled out of the condenser 2. For this reason, the piping path of the extraction pipe 4 is not linear as shown in FIG. 10, and piping work may be complicated.

Further, the feed water heater 3 is provided with an emergency drain pipe (not shown) for allowing the drain to escape directly to the condenser 2 in case the drain water level becomes abnormally high. The emergency drain pipe, though the heat transfer tubes 3 ₁ feed heater 3 is designed for condensate flow rate of the leak when broken, the interior assumed amount or more of condensate feedwater heater 3 When it leaks, there is a possibility that the drain flows back to the extraction pipe 4. Of course, it is possible to design by estimating the amount of condensate to be leaked, but in that case, it is necessary to increase the diameter of the drain pipe, and the control valve installed in the drain pipe also matches the pipe diameter and flow rate. It is necessary to select one, which is not preferable because of the layout of the power plant equipment and the increased equipment cost.

  In addition, in the case of the invention in which when the drain exceeds the predetermined water level in the feed water heater, it overflows through the U-shaped pipe and is discharged to the condenser, water induction can be prevented, but the flash when the load is interrupted There is a disadvantage that it can not cope with the back.

  Therefore, the present invention can prevent flashback phenomenon and water induction without requiring various valves and control devices such as a check valve, a gate valve, and a control valve, and does not require maintenance or maintenance or maintenance. An object of the present invention is to provide a highly reliable protection device for a steam turbine system that can be performed in a very simple manner.

  In order to achieve the above object, an embodiment of the present invention includes a steam turbine, a condenser that condenses exhaust steam from the steam turbine, and feed water that heats feed water or condensate with extracted steam from the steam turbine. In a protection device for a steam turbine system including a heater, and a bleed pipe connecting the steam turbine and the feed water heater, a communication pipe having a U-shaped pipe at an intermediate portion between the bleed pipe and the condenser And connecting the one end portion of the communication pipe to the extraction pipe from the position of the second connection portion to which the other end portion of the communication pipe and the condenser are connected. Is also provided at a lower position to form a free water surface in the communication pipe for the head of water based on the differential pressure between the pressure acting on the first connection portion and the pressure in the condenser acting on the second connection portion It is characterized by doing.

  Another embodiment of the present invention is a steam turbine, a condenser that condenses exhaust steam from the steam turbine, a feed water heater that heats feed water or condensate with extracted steam from the steam turbine, In a protection apparatus for a steam turbine system including the steam turbine and a bleed pipe for connecting the feed water heater, the feed water heater and the condenser are connected by a communication pipe having a U-shaped tube at an intermediate portion. In addition, the third connection portion where the one end portion of the communication pipe is connected to the feed water heater is lower than the position of the second connection portion where the other end portion of the communication pipe is connected to the condenser. A free water surface for the head of water based on the differential pressure between the pressure acting on the third connection portion and the pressure in the condenser acting on the second connection portion is formed in the communication pipe. It is characterized by.

  According to the present invention, flashback phenomenon and water induction can be prevented without requiring various valves and control devices such as a check valve, a gate valve, and a control valve, and maintenance and maintenance are unnecessary or It is possible to provide a highly reliable protection device for a steam turbine system that can perform maintenance extremely simply.

Schematic which shows the state at the time of normal operation of the protection apparatus of the steam turbine system which concerns on Embodiment 1 of this invention. Schematic which shows the state at the time of the pressure fall in the extraction pipe | tube of the protection apparatus of the steam turbine system which concerns on Embodiment 1 of this invention. Schematic which shows the state at the time of the heat exchanger tube fracture | rupture of the protection apparatus of the steam turbine system which concerns on Embodiment 1 of this invention. The schematic block diagram of a part of protection device of the steam turbine system which concerns on Embodiment 2 of this invention. Schematic which shows the state at the time of normal operation of the protection apparatus of the steam turbine system which concerns on Embodiment 3 of this invention. Schematic which shows the state at the time of normal operation of the protection apparatus of the steam turbine system which concerns on Embodiment 4 of this invention. The schematic block diagram of a part of protection device of the steam turbine system which concerns on Embodiment 5 of this invention. Schematic which shows the state at the time of normal operation of the protection apparatus of the steam turbine system which concerns on Embodiment 6 of this invention. The schematic block diagram of a part of protection apparatus of the steam turbine system which concerns on Embodiment 7 of this invention. The schematic block diagram which shows the connection state of the conventional steam turbine and a feed water heater.

Hereinafter, an embodiment of a protection device for a steam turbine system according to the present invention will be described with reference to the drawings.
(Embodiment 1)
A protection device for a steam turbine system according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 3.

  FIG. 1 is a schematic diagram illustrating a state during normal operation of the protection device for the steam turbine system according to the first embodiment of the present invention, and FIG. 2 illustrates a pressure drop in the extraction pipe of the protection device for the steam turbine system according to the first embodiment. FIG. 3 is a schematic diagram illustrating a state when the heat transfer tube of the protection device of the steam turbine system according to the first embodiment is broken.

  1 to 3, the protection device for a steam turbine system according to the first embodiment includes, as main components, a steam turbine 1, a condenser 2, a feed water heater 3, a bleed pipe 4, and a communication device. And a pipe 5.

The steam turbine 1 is configured so that steam can be extracted at a turbine stage on the way, and the extracted extracted steam S is supplied to a feed water heater 3 installed in the condenser 2 via an extraction pipe 4. It is configured as follows. Feed water heater 3 extraction steam S supplied to the inside is cooled by water or condensate heat exchange through heat transfer tubes 3 _1, it is retained in the feed water heater 3 as a drain 3 ₂ condenses . Hereinafter referred to as held water 3 ₂ drain 3 ₂ which is retained in the feed water heater 3.

  On the other hand, in the condenser 2, in order to condense and condense exhaust steam, which has been expanded by the steam turbine 1, to cool the seawater flowing in a heat transfer pipe (not shown) installed in the container. Turbine exhaust steam that has been cooled by water and condensed in the vessel is at saturation pressure and temperature. The above configuration is a configuration that is normally employed in a steam turbine system that introduces extracted steam into a feed water heater.

  In the first embodiment, the above-described steam turbine system is communicated between the extraction pipe 4 and the condenser 2 by a communication pipe 5 having a U-shaped pipe (also referred to as a U seal part) in the middle part. It is configured as described above.

The communication pipe 5 has one end of the two ends of the U-shaped tube 5 ₁ is connected to a site below the extraction pipe 4 through the lower connection tube 5 ₂ formed horizontally, the extraction pipe 4 inside and Communicate. The other end of the U-shaped tube 5 ₁ connected via the upper connecting pipe 5 ₄ formed in the pipe diameter enlarged portion 5 ₃ and L-shaped upwardly extending perpendicularly form the upper portion of the condenser 2 And communicated with the interior of the condenser 2. Here, the connection portion of the lower connecting tube 5 ₂ and the extraction pipe 4 is referred to as a first connection part 6, it referred the connection portion between the upper connecting pipe 5 ₄ and the condenser 2 and the second connection 7. Note that the position of the first connection portion 6 is set lower than the position of the second connection portion 7.

The pipe size enlargement unit ₃ located at the top of the U-shaped tube 5 _1, when the pressure drop event extraction pipe 4 occurs, as a change in water head appears in the pipe diameter enlarged portion 5 ₃ It is provided so that a large amount of water 8 is discharged from the communication pipe 5 into the condenser 2.

Then, initial water filling is performed from a water inlet (not shown) inside the communication pipe 5 configured as described above. Then, the extraction pipe 4 inside the pressure _{P 1} acting on the first connecting portion 6, the differential pressure between the condenser 2 the pressure _{P 2} acting on the second connecting part 7 _(P 1 -P ₂₎ content of the free water surface of the water 8 corresponding to water head "a" appears at the pipe size enlargement unit 5 _3. The position of the free water surface is stably held by the U-shaped tube 5 _1.

Hereinafter, the response of the protection device for the steam turbine system according to the first embodiment will be described in several cases.
(I) During Normal Operation FIG. 1 shows a state during normal operation of the protection device for the steam turbine system.
In the figure, “a”, “b”, and “c” all represent the head when the first connecting portion 6 is set to the reference water level (L ₁ ), among which “a” is as described above. a water head during normal operation of the steam turbine 1, the pressure difference between the condenser 2 the pressure P ₂ acting extraction pipe 4 inside the pressure P ₁ and the second connecting portion 7 that acts on the first connection part 6 corresponds to _(P 1 -P _2), the reference water level _{(L 1)} from the formed pipe diameter enlarged portion ₅ within ₃ the free water surface position of the first connection part 6 _{(L 2)} to the height (L It has maintained a ₂ -L _1). Further, "b" is the highest position (in this case, the top position in the pipe diameter enlarged portion 5 _3; L ₃₎ of the communicating pipe 5 from the reference water level (L ₁₎ of the first connecting portion 6 to the height (L ₃ -L ₁ ), and “c” is a height (L ₄ ) from the reference water level (L ₁ ) of the first connection portion 6 to the position (L ₄ ) of the connection portion of the steam turbine 1 and the extraction pipe _4. It corresponds to the -L _1).

Here, by water 8 communicating pipe 5 is exposed to the pressure P ₂ in the condenser 2, for drops below the saturation temperature of the condenser 2 in the pressure, constantly held by the feed water heater 3 energy than water 3 ₂ is maintained at a low state.

(Ii) When the pressure in the bleed pipe 4 is lowered FIG. 2 shows the state when the pressure in the bleed pipe 4 is lowered.
The cause of the pressure drop in the bleed pipe 4 is condensate when a load interruption occurs during the operation of the steam turbine system, or when the steam flowing into the steam turbine 1 decreases due to a stop event occurring in the steam generating section. This occurs when the pressure in the steam turbine 1 connected to the vessel 2 also decreases.

When the pressure in the feed water heater 3 which is connected by a steam turbine 1 and the extraction pipe 4 is reduced, since the held water 3 ₂ feed heater 3 has a feed water heater 3 in a saturated water pressure during normal operation , the Retained water 3 ₂ flushed, flashback phenomenon. Then, due to the pressure drop in the extraction pipe 4, the differential pressure (P ₁ -P ₂ ) between the pressure P ₁ acting on the first connection portion 6 and the pressure P ₂ acting on the second connection portion 7 is the steam turbine 1. It will be less than during normal operation. Level of free water surface by the normal pressure differential than when the operation is decreased down to L _5, hydrocephalus at this time is "a'". As a result, the pipe diameter enlarged portion ₅ water head difference from the inside ₃ (a-a') level differences in other words _(L 2 -L ₅₎ content of the water storage 8 communicating pipe 5 of the U-shaped tube _{5 1} and the lower as indicated by the arrow It is released from the first connecting portion 6 through the connecting pipe 5 ₂ extraction pipe 4 leading to the feed water heater 3.

The stored water 8 released at this time exchanges heat with the flash steam in the feed water heater 3 to condense the flash steam into saturated water and drop it into the feed water heater 3. By and is in the feedwater heater 3 is released held water 3 ₂ water are mixed, the temperature was reduced holdings water 3 _2, suppress the holdings water 3 ₂ flash. In this way, it is possible to prevent the flash steam from flowing into the steam turbine 1 and to prevent the flashback phenomenon.

In order to condense the flash steam to a level that does not affect the steam turbine 1 when the pressure of the extraction pipe 4 is reduced, it is necessary to discharge a sufficient amount of stored water. Therefore, in the first embodiment, the water head difference (a− to change the height position occurring in a'), amount that the cross-sectional area of the bore of the communicating pipe 5 increases by installing a pipe diameter enlarged portion 5 ₃ in which the increased diameter of the communication pipe 5, the releasable reservoir 8 Try to increase the amount.

Incidentally, on the basis of the pressure drop of the embodiment 1, the extraction pipe 4, the water head difference between the water storage 8 (a-a') a large amount of water so as to generate in the piping diameter enlarged portion 5 ₃ of the communication pipe 5 8 was as to release, without providing a pipe diameter enlarged portion 5 _3, such as by the entire communication pipe 5 and a large diameter, if so capable of releasing sufficient water to flush steam heat exchanger, it is not always necessary to install a pipe diameter enlarged portion 5 _3.

(Iii) at break Figure of the heat transfer tube 3, the feed water by the heater breakage of the heat transfer tubes 3 ₁ 3 holding water 3 ₂ in the feed water heater 3 is increased, showing a state in which flow back up to the extraction pipe 4 ing.
Water supply level of holdings Water 3 ₂ in the heater 3 is increased, and increased to the level of the height d of the extraction pipe 4 exceeds the level of the first connecting portion 6 to flow back to the extraction pipe 4. At this time, since the communicating pipe 5 for water level rise in the height d minutes only reservoir 8 of the water level, water 8 when also higher than the top height L ₃ of the water level pipe size larger unit 5 _3, condensate begins to overflow into the vessel 2, is released from L-shaped upper connecting pipe 5 ₄ communicating pipe 5 through the second connecting part 7 in the condenser 2.

Thus, by releasing the amount of held water 3 ₂ corresponding to the water level rise in the condenser 2 through the communicating pipe 5 from the extraction pipe 4, it is possible to prevent water induction to the steam turbine 1 .

Incidentally, when the water level rise in the holdings Water 3 ₂ feed heater 3, in order to prevent water induction is water head "b" when the reservoir 8 overflows, the water head "a" steady-state, the first connection It should be configured to be smaller than the sum of the water head “c” from the height of the portion 6 to the connection portion between the steam turbine 1 and the extraction pipe 4, that is, the conditional expression (b <a + c) must be satisfied. .

If the overflow head “b” exceeds the sum of the steady head “a” and the head “c” from the height of the first connection 6 to the connection between the steam turbine 1 and the extraction pipe 4. to become such a structure and (b ≧ a + c), reached a feed water heater 3 level holdings water 3 ₂ rose from the up connection between the steam turbine 1 and the extraction pipe 4 height c (L ₄₎ However, since the retained water cannot be discharged to the condenser 2 beyond the top height b (L ₃ ), water induction to the steam turbine 1 cannot be prevented.

In FIG. 3, although the heat transfer tubes 3 ₁ in the feed water heater 3 indicates to simulate the state of broken, why the held water 3 ₂ increases in the feed water heater 3, feed water heater 3 It is not limited only to break the heat transfer tubes 3 _1.

  As described above, according to the first embodiment, the flashback phenomenon, the water induction, the control valve, the check valve, the various valves such as the check valve, and the control valve that are used in the prior art are not provided. A highly reliable protection device for a steam turbine system can be provided. Moreover, since various valves such as a check valve, a gate valve, and a control valve and a control device are not required, maintenance and maintenance are unnecessary, or maintenance and maintenance can be performed very simply.

(Embodiment 2)
With reference to FIG. 4, the protection apparatus of the steam turbine system which concerns on Embodiment 2 of this invention is demonstrated. In addition, the same code | symbol is attached | subjected to the same structure as Embodiment 1, and the overlapping description is abbreviate | omitted suitably.

4, the embodiment 2 embodiment differs from the first, such as "lotus port" to the lower connecting pipe 5 _second open end of the communication pipe 5, installed sprinkler device 9 open a large number of small holes This is the point. This water sprinkling device 9 is intended to discharge the water storage 8 uniformly in the form of a shower in the extraction pipe 4 when the pressure of the extraction pipe 4 decreases.

According to the second embodiment, in addition to the effects of Embodiment 1, by placing the sprinkler system 9 to the opening end face of the lower connecting tube 5 ₂ communicating pipe 5, the water storage 8 and the flash vapor released is heat exchange Since the surface area is increased, the heat exchange with the flash vapor can be efficiently performed.

(Embodiment 3)
With reference to FIG. 5, the protection apparatus of the steam turbine system which concerns on Embodiment 3 of this invention is demonstrated. In addition, the same code | symbol is attached | subjected to the structure same as Embodiment 1, and the overlapping description is abbreviate | omitted suitably.

FIG. 5 shows the state of the third embodiment during normal operation of the power plant. 5, differs from the embodiment 1, the lower connecting pipe 5 ₂ communicating pipe 5 is not a horizontal shape as shown in FIG. 1, loosely inclined upper from the end of the U-shaped tube 5 _1, the distal portion The point where the first connection part 6 is formed so as to protrude into the extraction pipe 4 and the opening end surface of the first connection part 6 are installed so as to face the downstream direction of the extraction steam S flowing through the extraction pipe 4. and that are, a point that was installed drain recovery pipe 10 for supplying to and collecting the extraction steam drain communicating pipe 5 through the extraction pipe 4, further carried into the open end face of the lower connecting tube 5 ₂ communicating pipe 5 It is the point which installed the watering apparatus 9 similar to the form 2 (FIG. 4). Here, the extraction steam drain means that liquid phase water generated during the expansion process of the steam in the steam turbine 1 flows into the extraction pipe 4 and that which condenses when the extraction steam S flows through the extraction pipe 4. Point to.

Drain recovery pipe 10 is set at an appropriate site of higher than site first connecting portion 6 to incorporate the bleed steam drain flowing through the extraction pipe 4, connected between the intermediate portion of the part and the lower connecting tube 5 ₂ The incorporation Has been. Here, the middle portion of the lower connecting tube 5 _2, it is meant that between the end portion and the first connecting portion 6 which is connected to the U-shaped tube 5 _1.

  In the third embodiment, by installing the drain recovery pipe 10, it is possible to eliminate the need for initial water filling to the communication pipe 5 in the above-described first embodiment, and the water storage 8 of the communication pipe 5 is reduced for some reason. Even in this case, liquid phase water can always be supplied from the drain recovery pipe 10 as the extraction steam drain from the extraction pipe 4, so that it is not necessary to supply liquid phase water to the communication pipe 5. .

When the water storage 8 is filled up to the head “a” in the communication pipe 5, even if liquid phase water is supplied from the drain recovery pipe 10, the same amount of water as the supplied water is supplied to the lower connection pipe. since 5 ₂ back overflowed into the extraction pipe 4 from falling into the feed water heater 3, the water level of the pipe diameter enlarged portion 5 ₃ L ₂ is maintained without increase.

  According to the third embodiment, in addition to the effects of the first embodiment, it is not necessary to supply liquid water to the communication pipe 5 including initial water filling to the communication pipe 5, so that maintenance and maintenance can be further simplified. The effect of becoming can be obtained.

(Embodiment 4)
With reference to FIG. 6, the protection apparatus of the steam turbine system which concerns on Embodiment 4 of this invention is demonstrated. In addition, the same code | symbol is attached | subjected to the structure same as Embodiment 1, and the overlapping description is abbreviate | omitted.

FIG. 6 shows a state of the fourth embodiment during normal operation of the power plant. The present embodiment 4 differs from the embodiment 1, instead of extending the horizontal shaped portion of the lower connecting tube 5 ₂ until the extraction pipe 4, and configured to connect to the internal feed water heater 3 is bent to the lower side in the middle Is a point. Here, it referred to connection portions of the lower connecting tube 5 ₂ feed heaters 3 and the communication pipe 5 and the third connecting portion 11.
Although this Embodiment 4 has an effect equivalent to Embodiment 1 fundamentally, when the communication piping 5 is connected to the feed water heater 3, it has the characteristic which cannot be obtained in Embodiment 1. FIG.

That is, during normal operation of the steam turbine system, in order to form the free water surface of the water storage 8 in the communication pipe 5, the pressure (P ₃ ) acting on the third connection portion 11 and the pressure of the condenser 2 (P _The water storage 8 is filled in the communication pipe 5 by the amount “a” of the water head based on the pressure difference (P ₃ −P ₂ ) from ₂ ). At this time, the pressure (P ₃ ) acting on the third connection portion 11 is equivalent to the pressure in the feed water heater 3.

Also in the case of the fourth embodiment, when the pressure (P ₃ ) of the feed water heater 3 decreases due to load interruption or the like during operation of the steam turbine system, the retained water in the feed water heater 3 is the same as in the first embodiment. 3 ₂ flashes and a flashback phenomenon occurs, but the water head drops to “a ′” due to the pressure drop in the feed water heater 3, and the water head difference “a−a ′” from the steady state reservoir 8 is released to the feed water heater 3 from the third connecting portion 11 through the lower connection tube 5 ₂ communicating pipe 5. Since the water storage 8 hydrocephalus "a-a'" fraction which corresponds to the pressure drop from the third connecting portion 11 is discharged to the feed water heater 3, holding water 3 ₂ and reservoir 8 in the feed water heater 3 is mixed Retained water temperature decreases. As a result, the flash can be suppressed held water 3 _2, it is possible to prevent the flashback phenomenon.

In the fourth embodiment, since the stored water 8 is directly discharged into the feed water heater 3, the main purpose is to reduce the saturation temperature of the retained water rather than the heat exchange with the flash steam due to the pressure drop in the feed water heater 3. Become. In order to suppress the flash vapor to the extent not affecting the steam turbine 1, it is necessary to release the water in an amount sufficient to cool the held water 3 _2.

On the other hand, when the water level of the held water 3 ₂ feed heater 3 by heat transfer tubes 3 ₁ of breakage or the like during operation of the steam turbine system rises, also rises the water level of the communication pipe 5. If the water level of the water storage 8 in the communication pipe 5 exceeds the height “b” at the top, the water storage 8 overflows from the communication pipe 5 and is discharged into the condenser 2 through the second connection part 7. As a result, water induction can be prevented as in the first embodiment.

  As described above, according to the fourth embodiment, basically the same effect as in the first embodiment is obtained, but one end of the communication pipe 5 is replaced with the extraction pipe 4 and connected to the feed water heater 3. As a result, the flashback phenomenon can be prevented more than in the first embodiment.

  With reference to FIG. 7, the protection apparatus of the steam turbine system which concerns on Embodiment 5 of this invention is demonstrated. In addition, the same code | symbol is attached | subjected to the structure same as Embodiment 4, and the overlapping description is abbreviate | omitted.

The fifth embodiment, the tip opening end surface of the third connecting portion 11 of the lower connecting tube 5 ₂ and feed water heater 3 described in Embodiment 4, sprinkler system opened the large number of small holes, similar to FIG. 4 9 It is characterized by having installed. By attaching the third connecting portion 11 of the front end opening end face to the nozzle 9, at the time of pressure drop in the feed water heater 3, it is possible to release a wide range water in the feed water heater 3, cooling the held water 3 ₂ In addition, the effect of exchanging heat with the generated flash vapor can be obtained.
According to the fifth embodiment, since the surface area of heat exchange between the stored water and the flash steam that is released is increased as in the case of the second embodiment, heat exchange can be performed efficiently.

(Embodiment 6)
With reference to FIG. 8, the protection apparatus of the steam turbine system which concerns on Embodiment 6 of this invention is demonstrated. In addition, the same code | symbol is attached | subjected to the same component as Embodiment 4 mentioned above, and the overlapping description is abbreviate | omitted suitably.

FIG. 8 shows a state during normal operation of the power plant according to the sixth embodiment. 8, the present embodiment 6 is the embodiment 4 (FIG. 6) differs from that, instead of the lower connection tube 5 ₂ communicating with one end of the U-shaped tube 5 ₁ a horizontal shape, is inclined loosely on top A point that is bent downward from the intermediate portion and connected to the inside of the feed water heater 3, and a drain for collecting the bleed drain flowing in the bleed pipe 4 and replenishing the water storage 8 in the communication pipe 5 The recovery pipe 10 is installed.

Drain recovery pipe 10, a part incorporating the bleed steam drain flowing through the extraction pipe 4, set at an appropriate site of higher than the highest position of the lower connection tube 5 _2, and an intermediate portion of the part and the lower connecting tube 5 ₂ The incorporation Connected between. Here, the intermediate portion refers to an inclined portion that is slightly lower than the top portion that bends downward.

In the sixth embodiment, during normal operation of the steam turbine system, liquid-phase water flowing in the extraction pipe 4 is supplied from the drain recovery pipe 10 to the communication pipe 5, but the water storage 8 is stored in the communication pipe 5 at the water level L ₂ ( when it is filled to correspond) to the hydraulic head "a" is supplied water and an equal volume of water is returned to the extraction pipe 4 overflows from the lower connection tube 5 _2, it is supplied to the feed water heater 3. As a result, the water level of the pipe diameter enlarged portion 5 ₃ L ₂ is maintained without increase.
As described above, according to the sixth embodiment, the effects of the invention of the third embodiment can be obtained in addition to the effects of the fourth embodiment.

(Embodiment 7)
With reference to FIG. 9, the protection apparatus of the steam turbine system which concerns on Embodiment 7 of this invention is demonstrated. In addition, the same code | symbol is attached | subjected to the component same as Embodiment 1, and the overlapping description is abbreviate | omitted suitably.

This embodiment 7 is characterized in that it has installed a cooling device 12 for cooling the water 8 to the pipe diameter enlarged portion 5 ₃ of the communicating pipe 5. Reservoir 8 by the cooling device 12 is filled in the pipe diameter enlarged portion 5 ₃ is cooled to the necessary temperature sufficient to condense the flash steam.

  As described in the first embodiment and the fourth embodiment, when the pressure in the extraction pipe 4 or the feed water heater 3 decreases, the stored water 8 is discharged to the extraction pipe 4 or the feed water heater 3. Since the effect of condensing flash vapor is higher as the temperature of 8 is lower, the amount of stored water 8 to be released can be reduced.

In the example shown in FIG. 9, although installed a cooling device 12 to the pipe diameter enlarged portion 5 within _3, the present embodiment 7 is not limited to this, the pipe diameter enlarged portion of the communication pipe 5 5 ₃ other than the portion to be installed a cooling device 12 of the water storage 8 may be configured to cool. Further, a new pipe is connected in parallel to the communication pipe 5 so that the water storage 8 is circulated between the communication pipe 5 and the new pipe, and the cooling device 12 is installed in the new pipe. Thus, the water storage 8 may be cooled.

  As mentioned above, although several embodiment of this invention was described, these embodiment was shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Steam turbine, 2 ... Condenser, 3 ... Feed water heater, 3 ₁ ... Heat transfer pipe, 3 ₂ ... Retained water (drain), 4 ... Extraction pipe, 5 ... Communication pipe, 5 ₁ ... U-shaped pipe, 5 ₂ ... Lower connection pipe, 5 ₃ ... Pipe diameter enlarged part, 5 ₄ ... Upper connection pipe, 6 ... First connection part, 7 ... Second connection part, 8 ... Water storage, 9 ... Sprinkling device, 10 ... Drain recovery pipe, 11 ... 3rd connection part, 12 ... Cooling device.

Claims (7)

A steam turbine, a condenser that condenses exhaust steam from the steam turbine, a feed water heater that heats feed water or condensate with extracted steam from the steam turbine, and connects the steam turbine and the feed water heater In a protection device for a steam turbine system comprising a bleed pipe,
The extraction pipe and the condenser are connected by a communication pipe having a U-shaped pipe at an intermediate portion, and a first connection part where one end of the communication pipe is connected to the extraction pipe is connected to the communication pipe. The pressure acting on the first connection part and the condenser acting on the second connection part are installed at a position lower than the position of the second connection part where the other end of the condenser and the condenser are connected. A protection device for a steam turbine system, wherein a free water surface corresponding to a water head based on a pressure difference from an internal pressure is formed in the communication pipe. A steam turbine, a condenser that condenses exhaust steam from the steam turbine, a feed water heater that heats feed water or condensate with extracted steam from the steam turbine, and connects the steam turbine and the feed water heater In a protection device for a steam turbine system comprising a bleed pipe,
The feed water heater and the condenser are connected by a communication pipe having a U-shaped tube in the middle part, and a third connection part to which one end of the communication pipe and the feed water heater are connected is By installing it at a position lower than the position of the second connection part where the other end of the communication pipe and the condenser are connected, the pressure acting on the third connection part and the pressure acting on the second connection part A protection device for a steam turbine system, wherein a free water surface corresponding to a water head based on a pressure difference from a water tank internal pressure is formed in the communication pipe.   The highest part in the communication pipe is b, and the water head in the communication pipe corresponds to the differential pressure between the pressure acting on the first connection part or the third connection part and the pressure acting on the second connection part. Is a, and the height from the first connection part or the third connection part to the connection part of the steam turbine and the extraction pipe is c, the conditional expression of b> a + c is satisfied. The protection device for a steam turbine system according to claim 1 or 2.   A watering device having a plurality of small holes is attached to an opening end face of a first connection part between the communication pipe and the extraction pipe or a second connection part between the communication pipe and the feed water heater. Item 4. The steam turbine system protection device according to any one of Items 1 to 3.   One end portion of the communication pipe is protruded into the extraction pipe, and an opening end surface at the tip thereof is installed so as to face a downstream direction of the extraction steam flowing through the extraction pipe, and an intermediate portion of the communication pipe and the extraction pipe A drain recovery pipe is provided for connecting between any part of the liquid pipe, and liquid water flowing in the extraction pipe is guided to the communication pipe by the drain recovery pipe. The protection device for a steam turbine system according to any one of claims 4 to 5.   One end portion of the communication pipe is connected to the feed water heater, and a drain recovery pipe is provided to connect between an intermediate portion of the communication pipe and an arbitrary portion of the extraction pipe, and the extraction pipe is used to extract the extraction air. 5. The protection device for a steam turbine system according to claim 2, wherein liquid phase water flowing in the pipe is guided to the communication pipe.   The protection device for a steam turbine system according to any one of claims 1 to 6, further comprising a cooling device that cools the liquid-phase stored water filled in the communication pipe.

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