JPH07122487B2 - Moisture separation reheater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention removes moisture from steam having a high degree of wetness in, for example, a nuclear power plant, and then uses the steam by heating steam. The present invention relates to improvement of a reheated moisture separation reheater.

(Prior Art) Generally, in a nuclear power plant, a moisture separation reheater 1 as shown in FIG. 3 is installed between a high pressure turbine and a low pressure turbine. The moisture separator / reheater 1 includes a housing 3 in which a moisture separator 5 and a reheater 7 are arranged. Of these, the extraction steam of the high-pressure turbine and the steam generated in the reactor are passed through the reheater 7 as reheat steam.

The high-pressure steam turbine exhaust as the reheated steam is introduced into the housing 3 from the reheated wet steam introduction pipe 9 attached to the lower portion of the housing 3, and is contained in the reheated steam by the moisture separator 5. About 10% of moisture is removed. The reheated steam from which the moisture has been removed is then reheated by the reheating device 7 to become heated steam, which is discharged from the reburned heated steam discharge pipe 11 attached to the upper portion of the housing 3,
Guided to a low-pressure turbine.

On the other hand, the moisture (drain) separated by the moisture separator 5
Flows down through the moisture separator 5 by gravity, flows through a drain passage 17 formed by being surrounded by a bottom plate 13 and an upper bottom plate 15, and flows into a drain tank 19. Drain channel 17 and drain tank 19
And are connected by a drain guide (entrance) 21 connected to the bottom plate 13. Further, the drain temporarily stored in the drain tank 19 is guided to a feed water heater (not shown) through the drain discharge pipe 23.

A liquid level gauge 25 is attached to the drain tank 19, and the water level in the drain tank 19 is monitored to be constant. Then, by controlling a flow rate adjusting valve (not shown), the drain inflow amount introduced into the drain tank 19 and the drain discharge pipe 23
It is configured so that the amount of drain discharged from is equal.

(Problems to be Solved by the Invention) However, since the drain passage 17 has a long axial length, the distance between both ends of the drain passage 17 and the drain guide portion 21 is also long. In addition to this, since the bottom surface of the drain passage 17 is substantially horizontal, the flow of drain flowing on this bottom surface becomes gentle, and the drainage to the drain tank 19 is also poor,
In addition, the water level in the drain passage 17 becomes high because of the delay. In particular, the water level at both ends of the drain passage 17 is higher than the water level near the drain guide portion 21. As described above, when the drain water level in the drain passage 17 becomes high, the drain may flush in the drain passage 17 due to a sudden pressure drop in the housing 3 or other pressure fluctuations. This flush of the drain hinders the flow of the drain, and the water level of the drain in the drain passage 17 changes. As a result, the drain liquid level in the drain tank 19 becomes unstable, which is not preferable in controlling the water level in the drain tank 19. In addition, if the drain remains in the drain passage 17 for a long period of time, the drain itself may be decomposed or the drain passage may be corroded.

Therefore, both ends of the bottom plate 13 of the drain passage 17 are respectively raised to be inclined downward toward the drain guide portion 21 to improve the flow of the drain in the drain passage 17 so that the drain in the drain passage 17 is well drained. It is possible to reduce the water level. However, in this method, when the drain passage 17 is long in the axial direction of the housing 3, the height of both ends of the drain passage 17 is considerably increased in order to improve drainage performance of the drain due to the inclination of the bottom plate 13. Therefore, the drain passage 17 occupies a large proportion of the housing 3. Therefore, the size of the housing 3 is increased, which is not preferable in terms of equipment layout in the turbine building.

Therefore, an object of the invention is to enhance the drainage property of draining the drain in the drain flow path to the outside of the machine quickly and surely without increasing the size of the housing, thereby flushing the drain in the drain flow path and for a long time. It is an object of the present invention to provide a moisture separation reheater capable of stabilizing the corrosion and corrosion of the drain itself due to the residual, and further stabilizing the drain liquid level in the drain tank.

[Structure of Invention]

(Means for Solving Problems) The present invention is directed to a moisture separation unit that removes the moisture of the reheated steam introduced into the housing, and the moisture is removed through the moisture separation unit. And a reheating part for reheating steam, and is formed below the moisture separation part so as to partition the flow path of the reheated steam from the introduction part of the housing to the moisture separation part. And a drain channel for collecting the moisture removed in the moisture separation section as a drain and a drain tank for storing the drain in the drain channel by inflowing from the inlet opening in the drain channel. In the moisture separation reheater having, the both ends in the axial direction of the drain passage, while connecting the drain distribution pipe connecting to the drain tank, the bottom surface of the drain passage, the axial end portions and At the middle of the drain tank above the drain inlet, It is formed into a mountain-shaped inclined surface, and the connection portion between both ends of the drain flow path and the drain distribution pipe and the inlet of the drain tank are arranged at the tip of the downward slope of the mountain shape.

(Operation) The drain separated by the moisture separator and collected in the drain channel flows along the mountain-shaped inclined surface of the drain channel, and flows into the drain inlet of the drain tank by the natural free fall and the drain flow. The water flows to both ends of the road and is collected, and is led to the drain tank through the drain distribution pipe. For this reason, the drainage of the drain passage is improved, so that the drain can be quickly drained out of the machine. For this reason, the drain water level in the drain flow path can be reduced, so that the flash of the drain caused by the pressure change in the housing can be reduced, the drain liquid level in the drain tank can be stabilized, and the subsequent water level control is easy. Can be Further, in order to improve the drainage performance of the drain passage, it is possible to prevent the drain from remaining in the drain passage for a long period of time, and thus prevent the residual water from decaying and corroding the drain passage. be able to. Further, since the bottom surface of the drain flow path is formed into a mountain-shaped inclined surface having the apex at the intermediate portion between the both ends in the axial direction and the drain tank inlet, one end of the one-way flow is set so that both ends of the drain are higher than the drain tank inlet. The inclination angle can be made smaller than in the case. Therefore, it is possible to reduce the proportion of the drain passage in the housing and prevent the housing from becoming large.

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

FIG. 1 is a side view showing an embodiment of the moisture separation reheater according to the present invention with its essential parts broken away, and FIG. 2 is a sectional view taken along the line II-II of FIG. The moisture separation reheater 31 is symmetrical with respect to the longitudinal center position (center plane AA in the drawing),
Therefore, a part of the left half of the moisture separation reheater 31 in FIG. 1 is omitted, and the description thereof is also omitted.

The housing 33 of the moisture separation reheater 31 has a cylindrical shape extending in the lateral direction, and lid plates 35A and 35B are attached to both ends thereof to form a hermetically sealed structure. In the lower part of the housing 33 in the drawing, a plurality of reheated wet steam introducing holes 37 are provided at intervals in the axial direction of the housing 33. Further, in the lower part of the housing 33 in the drawing, these reheated and wetted introduction holes are provided.
A drain tank 39 and a shell drain discharge hole 41 are alternately installed between 37. Further, the reheated superheated steam discharge holes 43 are attached to the upper portion of the housing 33 in the figure at intervals in the axial direction.

Inside the housing 33, a cover plate partition plate 45 is provided near the cover plates 35A and 35B.
Is attached. Further, central partition plates 47A and 47B are installed at the central position in the housing 33 in the axial direction. These central partition plates 47A, B are configured to cover the bend portions of U-shaped heat transfer tubes 75A, 75B described later. Further, the upper portions of the central partition plates 47A and 47B in the figure are provided apart from the upper surface of the housing 33.

A bottom plate 49 and an upper bottom plate 51 are arranged above the bottom plate 49 in the housing 33. The bottom plate 49 and the upper bottom plate 51 extend in the longitudinal direction of the housing 33. Both ends of the bottom plate 49 and the upper bottom plate 51 are fixed to the central partition plate 47A and the lid plate partition plate 45. Below the bottom plate 49 in the figure, the steam distribution plate 53
Is provided. The steam distribution plate 53 also extends in the axial direction of the housing 33. The steam distribution plate 53 divides the reheated steam introduced from the reheated wet steam introduction hole 37 into the left and right sides in the drawing as shown in FIG.

As shown in FIG. 2, an inlet porous plate 55 and an outlet porous plate 57 are erected on both sides of the bottom plate 49 and the upper bottom plate 51 in the width direction. These inlet perforated plate 55 and outlet perforated plate 57
Also extends in the axial direction of the housing 33, and both ends thereof are fixed to the lid plate partition plate 45 and the central partition plate 47A. A steam inlet partition plate 59 is horizontally attached to the upper end portions of the inlet porous plate 55 and the outlet porous plate 57 in the figure. The vapor inlet partition plate 59 extends in the axial direction of the housing 33 and is fixed to the lid plate partition plate 45 and the central partition plate 47A, and its side edges are fixed to the inner surface of the housing 33.

Therefore, inside the housing 33, the entrance porous plate 55,
A steam distributor 61 is formed by being surrounded by the steam inlet partition plate 59 and the inner surface of the housing 33. In the vapor distributor 61,
The reheated steam split by the steam distribution plate 53 is introduced. In addition, an inlet perforated plate 55, an outlet perforated plate 57 and a vapor inlet partition plate.
A moisture separation unit 63 is formed surrounded by 59, and the moisture separation unit 63 is formed.
A moisture separator 65 is arranged in 63. Moisture separator 65
Removes the moisture of the reheated steam that has flowed in from the steam distributor 61 through the holes of the inlet porous plate 55.

A steam merging portion 67 is formed by being surrounded by the upper bottom plate 51 and the outlet porous plate 57. In this steam merging section 67, a moisture separation reheating device
The reheated steam from which moisture has been removed by the
Merge through 57.

On the vapor inlet partition plate 59, a surrounding plate 69 is erected at a position corresponding to the outlet porous plate 57. The reheating portion 71 is formed by being surrounded by the surrounding plate 69. The reheating section 71 is communicated with the steam merging section 67, and internally has the first-stage U-shaped heat transfer tube 75A of the first-stage reheating device 73A and the second-stage U-shape of the second-stage reheating device 73B. A heat transfer tube 75B is provided. The reheated steam introduced from the steam merging section 67 into the reheat section 71 is a U-shaped heat transfer tube for the first and second stages.
The heat is exchanged with the reheated steam flowing in 75A, B to be reheated to become superheated steam, which is discharged from the reheated superheated steam discharge hole 43.

As shown in FIG. 1, the steam first-stage and second-stage reheaters 73A, B are supported by a cover plate partition plate 45 and a central partition plate 47A. The first-stage reheating device 73A is arranged in the lower part of the drawing, and the second-stage reheating device 73B is arranged in the upper part of the drawing.
The extraction air from the high-pressure steam turbine is used as the first-stage reheat steam in the first-stage reheater 73A, and the steam generated in the reactor is used as the second-stage reheat steam in the second-stage reheater 73B. Be guided.

The first-stage and second-stage reheaters 73A and 73B have the same structure. That is, the first stage reheater 73A is composed of the first stage reheat header 77A and the first stage U-shaped heat transfer tube 75A, and the second stage reheater 73B is the second stage reheat header 77B and the second stage. It is composed of a U-shaped heat transfer tube 75B. The first-stage and second-stage reheat headers 77A and 77B are installed in an end space surrounded by the cover plate 35A and the cover plate partition plate 45. The first-stage and second-stage U-shaped heat transfer tubes 75A, B extend in the axial direction of the housing 33 and are supported by the support plate 79. The support plate 79 is fixed to the enclosing plate 69 as shown in FIG.

Partitions 8 in the first and second stage reheat headers 77A and 77B
1A and 81B divide into high temperature chambers 83A and 83B and low temperature chambers 85A and 85B, respectively. Also, the first and second stage reheat headers 77
The first-stage and second-stage U-shaped heat transfer tubes 75A, B are attached to the A, B tube plates 87A, 87B, respectively. Reheat steam introducing pipes 89A and 89B are connected to the high temperature chambers 83A and B of the first and second stage reheat headers 77A and B, respectively. The reheated steam introduced from the reheated steam introduction pipes 89A, B passes through the high temperature chambers 83A, B to the first
It is led to the stage and the second stage U-shaped heat transfer tubes 75A, B respectively.

In addition, the low temperature chamber 85 of the first and second stage reheat headers 77A, B
Vent vapor discharge pipes 91A and 91B and condensed drain discharge pipes 93A and 93B are connected to A and B. Part of the reheated steam from the first-stage and second-stage U-shaped heat transfer tubes 75A, B cooled by heat exchange is drained and discharged from the condensed drain discharge tubes 93A, B, and the rest is vent steam discharge. It is discharged from the pipes 91A and 91B.

On the other hand, a drain passage 95 is formed by being surrounded by the bottom plate 49 and the upper bottom plate 51. As shown in FIG. 2, the drain passage 95 communicates with the moisture separating unit 63, and collects the moisture removed by the moisture separating unit 63 as drain. At a position corresponding to the drain tank 39 on the bottom plate 49, as shown in FIG. 1, a main drain guide portion 96 as a drain tank connecting portion is provided.
Is attached. The drain on the bottom plate 49 is guided into the drain tank 39 via the main drain guide portion 96. The main drain guide portion 96, together with the bottom plate 49, also has a drain flow path that is guided from the drain flow path 95 to the drain tank 39, and the reheated steam from the reheated wet steam inlet 37 to the steam distribution unit 61. It also fulfills the function of separating from the flow path of. That is, as shown in FIG. 2, the drain channel 95 prevents the steam introduced from the steam inlet 37 from being directly introduced into the drain channel 95.
By partitioning with the bottom plate 49 and the main drain guide section 96, it is possible to prevent the drain once separated by the moisture separation section 63 from being re-engaged with the introduced steam flow and lowering the moisture separation efficiency.

As shown in FIG. 1, sub-drain guide portions 97 as drain distribution pipe connecting portions are attached to both axial end portions of the bottom plate 49. A drain flow dividing pipe 98 is connected to the lower portion of the housing 33 in the drawing so as to correspond to the sub-drain guide portion 97. The drain distribution pipe 98 is further directly connected to the drain tank 39. Therefore, the drain in the drain flow path 95 is guided directly into the drain tank 39 via the main drain guide section 96, and also through the sub-drain guide section 97.
It is guided to the inside of the drain tank 39 through 98, and the drain tank 39
It is temporarily stored inside.

Further, the bottom plate 49 is formed in a mountain-shaped inclined surface which forms the highest apex at a substantially middle position between the main drain guide portion 96 and the sub drain guide portion 97 in the axial direction of the housing 33, and the main drain guide portion 96 and the sub drain guide portion are formed. It is configured to incline downward toward the portion 97. The height difference of the bottom plate 49 is set to about 50 mm with respect to the axial length of 12 m on one side of the central plane AA, for example.

A drain discharge pipe 99 is connected to the drain tank 39, and a liquid level gauge 100 is installed. By adjusting a flow control valve (not shown) while monitoring the liquid level gauge 100, the drain inflow amount and the drain outflow amount to the drain tank 39 are controlled to be the same, and the drain liquid level in the drain tank 39 is kept constant. . Next, the flows of the reheated steam, the reheated steam, and the drain will be described.

First, the reheated steam flows into the housing 33 through the reheated wet steam introduction hole 37, is divided into two by the steam distribution plate 53, and reaches the inside of the steam distribution unit 61. The reheated steam that has flowed into the steam distribution unit 61 flows into the moisture separation unit 63, the moisture is removed while passing through the moisture separation device 65, and then flows into the steam merging unit 67. The reheated steam flows from the steam merging section 67 into the reheat section 71, and while flowing outside the first-stage and second-stage U-shaped heat transfer tubes 75A, B, the first-stage and second-stage U Character heat transfer tube 75A,
Heat is exchanged with the first-stage and second-stage reheat steam flowing in B to become superheated steam. The reheated steam that has become superheated steam flows out from the reheated superheated steam discharge hole 43 and is sent to a low-pressure turbine (not shown).

On the other hand, the first-stage and second-stage reheated steam passes through the reheated steam introduction pipes 89A and B, respectively, and goes into the high temperature chambers of the first-stage reheat headers 77A and B.
It flows into 83A, B, is divided into a plurality of first-stage and second-stage U-shaped heat transfer tubes 75A, B, and passes through the heat transfer tubes. During this time, the first-stage and second-stage reheated steam gradually exchanges heat with the reheated steam flowing outside the first-stage and second-stage U-shaped heat transfer tubes 75A, B as described above. It is cooled and condensed into a gas-liquid two-phase flow. Further, the flow mode of the reheated steam changes to an annular flow, a wavy flow, or a laminar flow while flowing in the first-stage and second-stage U-shaped heat transfer tubes 75A, B.

In the first-stage and second-stage reheated steam that has become a gas-liquid two-phase flow, the drain as a liquid phase is condensed from the low temperature chambers 85A, B to the condensation drain discharge pipe 9
It is discharged through 3A and B. Further, the uncondensed vapor as a gas phase is discharged from the low temperature chambers 85A, B through the vent vapor discharge pipes 95A, B.

Now, the moisture (drain) separated from the steam to be reheated by the moisture separator 65 flows down from the moisture separator 65 into the drain passage 95 by gravity and is collected. The drain in the drain flow path 95 is divided into two parts, the ridgeline at the top of the bottom plate 49, as a watershed, to the side of the mendrain guide 96 and the side of the subdrain guide 97, and flows along the mountain-shaped inclined surface by a natural drop. The drain toward the main drain guide section 96 side flows directly into the drain tank 39 from the main drain guide section 96. Further, the drain toward the sub-drain guide portion 97 side flows into the drain tank 39 from the sub-drain guide portion 97 through the drain distribution pipe 98. The drain is flow controlled and the drain tank 39
The water is sent from a drain discharge pipe 99 to a feed water heater (not shown).

Therefore, according to the above-described embodiment, since the sub-drain guide portion 97 mounting side of the drain flow passage 95, which is distant from the main drain guide portion 96, is connected to the drain tank 39 by the drain flow dividing pipe 98, the drain flow passage 95 is connected. The drain tank 39 is provided for draining the drained water through the drain flow path 95 and the drain distribution pipe 98.
Therefore, the drain amount in the drain passage 95 can be reduced. As a result, it is possible to reduce the flushing of the drain in the drain passage 95 without increasing the size of the housing 33, stabilize the drain liquid level in the drain tank 39, and suitably control the drain water level in the drain tank 39. Can be executed.

Further, the bottom plate 49 of the drain flow path 95 is formed as the highest top part at a substantially intermediate position between the main drain guide portion 96 and the sub drain guide portion 97, and the main drain guide portion 96 and the sub drain guide portion 97 are provided.
Since it is inclined downward toward the drain flow path 95, the drain flow can be improved in the drain flow path 95, and the drainage can be improved, so that the drain amount in the drain flow path 95 can be further reduced. , Drain can be quickly drained out of the machine. Therefore, the flush of the drain in the drain passage 95 can be further reduced, and the drain water level in the drain tank 39 can be suitably controlled.

Further, since the bottom plate 49 is inclined toward the main drain guide portion 96 and the sub drain guide portion 97 with the approximately middle portion as the top of the mountain-shaped inclined surface, when the bottom plate 49 is formed on the one-way inclined surface. It is not necessary to increase the axial length of the drain passage 95 as compared with the above. Therefore, the ratio of the drain passage 95 to the housing 33 is small, and the housing
33 can be prevented from increasing in size.

Further, the bottom plate 49 is formed as a mountain-shaped inclined surface which forms a top at a substantially middle position between the main drain guide portion 96 and the sub-drain guide portion 97, which means that the bottom plate at the position directly above the reheated wet steam introduction hole 37 is formed.
It means that 29 has risen. Therefore, the steam to be reheated enters the housing 33 through the steam introduction hole 37, and the steam distributor
The resistance to the flow of reheated steam flowing into 61 can be reduced. Then, since the drain passage 95 is separated from the introduced steam passage from the steam introduction hole 37 to the moisture separation portion 63 by the bottom portion 49 and the main drain guide portion 96, it is separated by the moisture separation portion 63. It is possible to prevent the moisture separation efficiency from being lowered due to the entrained drain in the introduced steam flow.

〔The invention's effect〕

As described above, according to the moisture separation reheater of the present invention, the drain separated by the moisture separator and collected in the drain passage flows along the mountain-shaped inclined surface of the drain passage. ,
It flows into the drain inlet of the drain tank due to a natural head, flows to both ends of the drain inflow, and collects water, which then leads to the drain tank through the drain distribution pipe. For this reason, the drainage property of the drain flow path is improved, and the drain can be quickly drained out of the machine. For this reason, the drain water level in the drain passage can be reduced, so that the flash of the drain caused by the pressure change in the housing can be reduced, the drain liquid level in the drain tank can be stabilized, and the subsequent water level control can be facilitated. can do. Further, in order to improve the drainage performance of the drain passage, it is possible to prevent the drain from remaining in the drain passage for a long period of time, and thus prevent the residual water from decaying and corroding the drain passage. be able to. Further, since the bottom surface of the drain flow path is formed into a mountain-shaped inclined surface having the apex at the intermediate portion between the both ends in the axial direction and the drain tank inlet, one end of the one-way flow is set so that both ends of the drain are higher than the drain tank inlet. The inclination angle can be made smaller than in the case. Therefore, it is possible to reduce the proportion of the drain passage in the housing and prevent the housing from becoming large.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a moisture separation reheater according to the present invention with a part omitted and a main part broken away, and FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a side view showing a part of a conventional moisture separation reheater with a part thereof omitted and the part broken away. 31 …… Moisture separation reheater, 33 …… Housing, 39 …… Drain tank, 49 …… Bottom plate, 51 …… Top bottom plate, 63 …… Moisture separation section, 65 …… Moisture separation device, 71… … Reheat part, 73A …… First
Stage reheater, 73B ... Second stage reheater, 95 ... Drain passage, 96 ... Main drain guide, 97 ... Sub drain guide, 98 ... Drain distribution pipe.

Claims (1)

[Claims] Claim: What is claimed is: 1. A moisture separating section for removing moisture of reheated steam introduced into a housing, and a reheating section for reheating the steam from which moisture has been removed after passing through the moisture separating section. And is formed below the moisture separation section so as to partition the flow path of the reheated steam from the introduction section of the housing to the moisture separation section. A moisture separation reheater having a drain channel for collecting the removed moisture as a drain and a drain tank for storing the drain in the drain channel by allowing the drain to flow from an inlet opening in the drain channel. In, while connecting both ends in the axial direction of the drain passage to a drain distribution pipe that connects to the drain tank, the bottom surface of the drain passage is located between the axial end portions and the drain inlet of the drain tank. Is formed on the mountain-shaped slope that forms the top of the mountain. Of the previous downward slope, and the connecting portion between both end portions of the drain passage and the drain distribution pipe, moisture separator reheater, characterized in that arranged an inlet of the drain tank.