JP2013039501A - Multistage type steam-water separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the outflow speed of steam flowing out of a cooling water discharge port formed at the lower end of an outer cylinder located above a cooling water surface and to suppress carryover amount by using a simple and inexpensive means.SOLUTION: The outer cylinder 34 of a second stage steam-water separation part 30 is located above the cooling water surface L. A porous plate 40 is provided to the cooling water discharge port 34a formed at the lower end of the outer cylinder 34. A large number of circular cooling water outflow pores 42 are bored on the porous plate 40. Thereby the outflow speed of the steam flowing out of the discharge port 34a is reduced and shock caused by collision of the steam against the cooling water surface L is alleviated and droplets are prevented from dispersing. As a result, the carryover amount is reduced.

Description

  The present invention relates to an air / water separator that separates water vapor from cooling water, and is particularly suitable when applied to a steam generator of a nuclear power plant.

  Since the steam generator of a nuclear power plant separates liquid components from the steam supplied to the steam turbine, a steam separator is usually provided at the top of the steam generator, and a moisture separator above the steam separator. Is provided. The droplets contained in the steam separated by the steam separator are removed by the moisture separator and then supplied to the steam turbine. Patent Document 1 discloses a configuration of a steam separator provided in a steam generator. Hereinafter, the configuration of the steam separator disclosed in Patent Document 1 will be described with reference to FIG.

  In FIG. 5, the steam / water separator 100 has a plurality of steam / water separators 110 and steam / water separators 120 arranged one above the other. The first stage steam-water separation unit 110 disposed in the lower stage includes an inner cylinder (riser) 112 and an outer cylinder (downcomer) 114 so as to surround the inner cylinder 112, and an orifice section 116 at the upper end of the inner cylinder 112. Is provided and communicates with the inner cylinder 112 of the steam / water separator 120 via the orifice 116. Between the inner cylinder 112 and the outer cylinder 114, a cooling water flow path s is formed in which cooling water separated from the gas phase in the inner space of the inner cylinder 112 flows down. The second-stage steam-water separation unit 120 has the same configuration, and includes an inner cylinder 122, an outer cylinder 124, and an orifice portion 126.

  Inside the inner cylinder 112, a plurality of swirl blades 118 are fixed at equal intervals. As a result, the gas-liquid two-phase flow t containing the bubbles g and rising inside the inner cylinder 112 is given a swirl force when passing through the swirl vanes 118 and becomes a swirl flow. Since a large centrifugal force is generated in the heavy liquid phase due to the swirling flow, the liquid phase flows along the wall surface of the inner cylinder 112, forms a liquid film m, and flows out into the outer cylinder 114. On the other hand, the gas phase rises in a state including some droplets l and is further separated into a gas phase and a liquid phase by the second-stage steam-water separation unit 120 in the upper stage. The water vapor separated from the liquid phase in the second stage water / water separation unit 120 flows into the moisture separator (not shown) via the vapor discharge pipe 130.

  At this time, the liquid phase descending due to gravity inside the outer cylinder 114 is accompanied by a part of the gas phase in the form of bubbles g or the like (Caranda). Further, the liquid phase is accompanied in the form of droplets or the like in the gas phase rising up the inner cylinder 112 (carryover). In the steam / water separator 100, a resistance 119 having a labyrinth structure is provided at a cooling water discharge port provided at a lower portion of the outer cylinder 114 of the first-stage steam / water separation unit 110 to reduce a gas phase to be carried. ing.

  The reason for providing a plurality of air / water separators is that the number of air / water separators increases compared to the case of only one stage, so that the air / water separation performance can be improved, and the swirl depends on the flow situation of each stage. This is because the air-water separation performance can be improved and the pressure loss of the flow can be reduced by optimizing the shape of the blades and the like.

  In Patent Document 2, in a multi-stage type steam / water separator, a large number of flow passage holes are formed in the inner cylinder and the outer cylinder of the upper stage side water / water separator, and a demister is provided between the inner cylinder and the outer cylinder. A structure for filling is disclosed. This configuration will be described with reference to FIG. The first-stage steam-water separator 210 of the steam-water separator 200 is provided with a diffuser 212 at the upper end of the stand pipe 202. Inside the diffuser 212, a hub 214 is connected between the hub 214 and the diffuser inner wall. A swirl vane 216 is provided. An inner cylinder 218 is connected to the upper end of the diffuser 212.

  A plurality of drainage channels partitioned by a partition plate 222 are formed between the inner cylinder 218 and the outer cylinder 220. An orifice portion 224 is provided at the upper end of the outer cylinder 220. The inner cylinder 218 communicates with the inner cylinder 232 of the second stage steam-water separation unit 230 via the orifice unit 224. The outer cylinder 234 is disposed with a space from the inner cylinder 232, and a demister 236 is filled between the inner cylinder 232 and the outer cylinder 234. The upper end of the interval is shielded by a shielding disc 238. The inner cylinder 232 and the outer cylinder 234 are provided with a large number of flow path holes 240 throughout the entire area.

  In such a configuration, the cooling water droplets and a part of the steam that have flowed into the inner cylinder 232 of the second-stage steam-water separator 230 flow into the flow path hole 240 of the inner cylinder 232, and only the droplets are discharged by the demister 236. Is captured. The liquid droplets captured by the demister 236 gravity drop in the drainage flow path between the inner cylinder 232 and the outer cylinder 234, and drop onto the cooling water surface L from the lower end opening of the outer cylinder 234. The steam that has passed through the demister 236 passes through the flow passage hole 240 of the outer cylinder 234 to the outside of the steam separator 200 and flows into a steam dryer (not shown).

JP 2002-326002 A JP 2004-245656 A

  In the multi-stage air / water separator, the cooling water discharge port of the outer cylinder (downcomer) may be located above the liquid level L in the upper-stage air / water separator. In this case, the vapor containing droplets flows downward from the cooling water discharge port, and collides with the lower cooling water surface with its momentum. As a result, droplets are scattered from the cooling water surface. The scattered droplets flow out to the upper part of the steam separator along with the gas phase and increase the moisture that is carried over, thereby deteriorating the steam separator performance.

  In the second-stage steam-water separator of the steam-water separator disclosed in Patent Document 2, a part of the cooling water droplets and steam flowing between the inner cylinder and the outer cylinder are gas-liquid separated by a demister, Flows out from the flow path hole 240 to the outside of the outer cylinder 234, so it is considered that the flow speed of the liquid droplet flowing down from the lower end discharge port of the outer cylinder 234 to the cooling water surface L is reduced. However, since it is necessary to make the flow path hole 240 in the entire area of the inner cylinder and the outer cylinder, it takes time and effort for processing. Further, since the demister is filled in the gap between the inner cylinder and the outer cylinder, there is a problem that the manufacturing cost becomes high.

  In view of the problems of the prior art, the present invention reduces the velocity of steam including droplets flowing out from the discharge port formed at the lower end of the outer cylinder located above the cooling water surface, so that the droplets from the cooling water surface. An object of the present invention is to prevent scattering and reduce the carryover amount, and to realize this by simple and low-cost means.

  In order to achieve such an object, the steam separator of the present invention comprises an inner cylinder that forms a gas-liquid two-phase flow ascending flow path and an outer cylinder that forms a downward cooling water flow path between the inner cylinder and the inner cylinder. In the steam / water separator, the internal space of the inner cylinder arranged adjacent to the top and bottom is communicated via a communication passage. In the air / water separator where the outlet formed in the lower end of the outer cylinder is located above the cooling water surface, the outer cylinder of the front stage air / water separator immediately below the outlet or the outlet, or around the outer cylinder just above the outlet Is provided with a flow velocity reduction mechanism.

  In the steam / water separator according to the present invention, by providing the flow velocity reduction mechanism, it is possible to mitigate the impact when the vapor containing the droplet collides with the cooling water surface. As a result, it is possible to prevent the droplets from scattering from the cooling water surface, and to prevent the scattered droplets from being taken into the gas phase side and the carryover amount from increasing.

  In the apparatus of the present invention, the flow velocity reduction mechanism is composed of a porous ring member attached to the cooling water discharge port of the outer cylinder, and the porous ring member gives resistance to the steam flowing out from the cooling water flow path, It would be good to reduce the speed. Thereby, it is possible to prevent an impact when the vapor containing the droplet collides with the cooling water surface by a simple and low-cost means. Further, by attaching the porous ring member to the discharge port, the flow rate of the steam can be reliably reduced. The shape of the hole drilled in the porous ring member may be, for example, a circle or a slit shape.

  In the apparatus of the present invention, a porous ring member provided in a direction intersecting the axial direction of the outer cylinder is provided around the outer cylinder of the front-stage steam-water separator immediately below the cooling water discharge port. It is preferable that resistance is given to the steam flowing out from the path and the flow rate of the steam is reduced. Accordingly, the flow rate of the steam discharged from the cooling water discharge port of the outer cylinder can be surely reduced with a simple and low-cost configuration using only the porous ring member. Moreover, the resistance of the porous ring member to the flowing-down steam can be reduced.

  In the apparatus of the present invention, the flow velocity reduction mechanism is configured by forming a region immediately above the cooling water discharge port of the outer cylinder with a porous cylindrical body, and discharging the steam from a steam exhaust hole formed in the porous cylindrical body. Thus, it is preferable that the flow rate of the steam flowing down from the cooling water discharge port is reduced. By letting the steam escape from the steam discharge hole, the steam containing the droplets gradually flows out of the outer cylinder, and the flow velocity is lowered as a whole, so that the droplets can be prevented from scattering from the cooling water surface. Moreover, it does not become resistance of the cooling water flowing down the inside of the outer cylinder.

  Furthermore, the steam flow rate can be reduced with a simple and low-cost configuration in which a steam discharge hole is provided in the region directly above the cooling water discharge port of the outer cylinder. Moreover, pressure loss can be reduced as compared with the case where a porous ring member is provided at the lower end of the outer cylinder, and the steam falling flow rate can be adjusted by adjusting the number of steam discharge holes.

  According to the multistage type steam-water separator of the present invention, steam-water comprising an inner cylinder that forms a gas-liquid two-phase flow rising channel and an outer cylinder that forms a downward cooling water channel between the inner cylinder and the inner cylinder. In the steam-water separator, in which the separation part is arranged in a plurality of stages in the vertical direction, and the inner space of the inner cylinder arranged adjacent to the top and the bottom is communicated via a communication passage, the outer cylinder of the steam-water separation part In the steam / water separation section where the discharge port formed at the lower end of the water is positioned above the cooling water surface, the flow velocity flows around the discharge tube or the outer cylinder of the front-stage steam / water separation unit immediately below the discharge port, or the outer tube just above the discharge port Since the reduction mechanism is provided, the flow speed of the steam flowing down from the outlet at the lower end of the outer cylinder is reduced by simple and low-cost means, and the impact when the steam collides with the cooling water surface is reduced. It is possible to prevent droplet carry-over by eliminating the scattering of the droplet.

It is a front view sectional view concerning a 1st embodiment of the device of the present invention. It is a partially expanded view of 1st Embodiment. It is front view sectional drawing concerning 2nd Embodiment of this invention apparatus. It is front view sectional drawing concerning 3rd Embodiment of this invention apparatus. It is a front view sectional view of the conventional steam separator. It is front view sectional drawing of the conventional steam-water separator of another structure.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
A first embodiment of the device of the present invention will be described with reference to FIGS. In FIG. 1, the steam-water separator 10 of this embodiment consists of a two-stage steam-water separator. The steam separator 10 is provided in the upper part of the steam generator of a nuclear power plant. In the steam generator, heat is exchanged between the primary cooling pressurized water for cooling the reactor containment vessel and the secondary cooling water, and the secondary cooling water is boiled. The temperature of the secondary cooling water reaches a saturation temperature near 300 ° C. under high pressure. The boiled secondary cooling water is separated into steam and water by the steam separator 10 and the moisture separator, and the steam turbine is driven by the separated steam.

  In the first stage steam / water separator 20 of the steam / water separator 10, a cylindrical inner cylinder 22 and an outer cylinder 24 are arranged concentrically and separated from the gas phase between the inner cylinder 22 and the inner cylinder 22. A cooling water flow path s for discharging the cooling water that has become hot water is formed. A swirl vane 26 is mounted in the inner space of the inner cylinder 22. The gas-liquid two-phase flow t rising from the lower side of the inner cylinder 22 passes through the fixed swirl vanes 24 and is given a swirl force to become a swirl flow. The lower end of the outer cylinder 24 is opened to form a cooling water discharge port 34a. An orifice portion 28 is provided at the upper end of the outer cylinder 24.

  A second stage steam / water separator 30 is provided above the first stage steam / water separator 20. The second-stage steam-water separation unit 30 has the same configuration as the first-stage steam-water separation unit 20, and includes an inner cylinder 32 and an outer cylinder 34, and a cooling water flow is provided between the inner cylinder 32 and the outer cylinder 34. A path s is formed. The inner cylinder 32 and the inner cylinder 22 communicate with each other via the orifice portion 28. An orifice 36 is provided at the upper end of the outer cylinder 34, and the inner space of the inner cylinder 32 is connected to a moisture separator (not shown) via a steam discharge pipe 38 connected to the orifice 36.

  The discharge port 34 a at the lower end of the outer cylinder 34 of the second stage steam / water separator 30 is located above the cooling water surface L. A ring-shaped perforated plate 40 is attached to the discharge port 34a so as to cover the discharge port 34a. As shown in FIG. 2, a large number of circular cooling water outflow holes 42 are formed in the porous plate 40.

  In such a configuration, the gas-liquid two-phase flow t rising from the lower side of the inner cylinder 22 of the first-stage steam-water separation unit 20 includes the steam g and is given a swirl force through the swirl vanes 26, It becomes. Accordingly, centrifugal force is applied to the liquid phase having a large weight, and a liquid film m is formed on the inner wall of the inner cylinder 22. The liquid phase containing a part of the vapor g flows out into the cooling water flow path s.

  The steam containing the remaining droplets 1 flows from the orifice portion 28 into the inner space of the inner cylinder 32 of the second stage steam / water separation portion 30. Here, the remaining droplets are separated and flow out into the cooling water channel s together with a part of the steam. The remaining steam flows out through the orifice 36 to the moisture separator.

  In the present embodiment, the porous plate 40 is provided at the discharge port 34 a of the outer cylinder 34, and the vapor g containing droplets is received by the porous plate 40. As shown in FIG. 2, a large number of circular cooling water outflow holes 42 are formed in the porous plate 40. By causing the steam that has flowed down from the discharge port 34a to flow into the cooling water outflow hole 42, pressure loss is caused in the flowing steam, and the flow speed of the steam can be reduced. Therefore, it is possible to prevent the vapor from colliding with the cooling water surface L and scattering the droplets. Therefore, the carry-over amount of the droplet can be reduced. Moreover, since the perforated plate 40 is disposed so as to cover the discharge port 34a, the outflow speed of the steam can be reliably reduced.

  In addition, although the outflow speed of a vapor | steam changes according to the cross-sectional area of the drainage space s, and the flow volume in a steam-water separator, for example, the outflow speed becomes 2.0 m / s vicinity. On the other hand, a stainless steel perforated plate having cooling water outflow holes 42 as shown in FIG. 2 was used, the cooling water outflow holes 42 had a hole diameter of 12.7 mm, a pitch of 15.0 mm, and an opening ratio of 0.65. When the steam outflow rate can be reduced to 0.3 m / s or less.

(Embodiment 2)
Next, a second embodiment of the device of the present invention will be described with reference to FIG. The present embodiment is an example in which a ring-shaped perforated plate 50 is provided in the horizontal direction at the upper end of the outer peripheral surface of the outer cylinder 24 of the first stage steam-water separation unit 20. As in the first embodiment, the circular perforated plate 50 has a large number of circular cooling water outflow holes. Other configurations are the same as those of the first embodiment.

  Thus, by providing the perforated plate 50 outside the upper surface of the outer cylinder 24 at the position facing the drain port of the second stage water / water separator 30, it is possible to reliably prevent steam from the discharge port toward the cooling water surface. Can give resistance. Therefore, the outflow speed of steam can be reduced. Accordingly, it is possible to prevent the cooling water from colliding with the cooling water surface L and scattering the droplets. Furthermore, since the perforated plate 50 is disposed away from the discharge port 34a, the pressure loss can be reduced because the perforated plate 50 is disposed outside the steam-water separator and does not close the discharge port as compared with the first embodiment. There are advantages.

(Embodiment 3)
Next, 3rd Embodiment of this invention apparatus is described based on FIG. In the present embodiment, the lower half region of the outer cylinder 34 of the second-stage steam-water separation unit 30 is configured with a porous cylindrical body 60 in which a large number of circular steam discharge holes 62 are dispersedly arranged. As a result, when the steam flows down through the outer cylinder 34, the steam escapes from the steam discharge hole 62, so that the steam including droplets gradually flows out of the outer cylinder, and the outflow of steam flowing out from the discharge port 34a. The speed can be reduced, and it is possible to prevent the steam from colliding with the cooling water surface L and scattering the droplets.

  Moreover, in this embodiment, since the discharge port 34a is kept open, the outflow resistance of the cooling water does not increase, and it flows out of the discharge port 34a by adjusting the arrangement region and the number of the steam discharge holes 62. There is an advantage that it becomes easy to adjust the flow rate of the steam. In the present embodiment, the steam discharge hole 62 may be formed in the lower region of the existing outer cylinder 34.

  In the first to third embodiments, the cooling water outflow holes 42 provided in the porous plates 40 and 50 or the drainage outflow holes 42 formed in the porous cylindrical body 60 are circular, but other shapes are used. For example, it may be a slit shape. In the first to third embodiments, each is an example provided with a two-stage steam-water separator, but the present invention can also be applied to one provided with three or more stages of steam-water separators.

  Furthermore, in 1st-3rd embodiment, all are the examples by which the swirl | wing blade 26 was mounted | worn in the inner space of the inner cylinder 22 of the 1st stage steam-water separation part 20, However, The steam-water separation part after the 2nd stage You may make it provide a turning blade | wing in. Thereby, by optimizing the shape of the swirl vanes according to the flow situation of each stage, the steam-water separation performance can be improved and the pressure loss of the flow can be reduced.

  According to the present invention, in the steam / water separator having a plurality of steam / water separators, the outflow speed of the steam flowing out from the upper-stage steam / water separator is reduced by simple and low-cost means, and the droplets are scattered. An increase in carryover amount can be effectively suppressed.

10, 100, 200 Air / water separators 20, 110, 210 First stage air / water separators 30, 120, 230 Second stage air / water separators 22, 32, 112, 122, 218, 232 Inner cylinders 24, 34, 114, 124, 220, 234 Outer cylinder 26, 118, 216 Swivel blade 28, 36, 116, 126, 224 Orifice portion 34a Discharge port 38, 130 Steam discharge pipe 40, 50 Perforated plate (porous ring member)
42 Cooling water outflow hole 60 Porous cylindrical body 62 Steam discharge hole 202 Stand pipe 212 Diffuser 214 Hub 222 Partition plate 236 Demister 238 Shielding disc 240 Channel hole g Steam l Droplet m Liquid film s Cooling water channel t Gas liquid Two-phase flow

Claims (4)

A steam / water separation section composed of an inner cylinder that forms an ascending flow path for a gas-liquid two-phase flow and an outer cylinder that forms a downward cooling water flow path between the inner cylinder and the inner cylinder is arranged in multiple stages in the vertical direction In the steam-water separator, the inner space of the inner cylinder arranged adjacent to the upper and lower sides is communicated via a communication passage.
Among the steam / water separators, in the steam / water separator where the outlet formed in the lower end of the outer cylinder is located above the cooling water surface, the outer cylinder of the outlet / water separator immediately below the outlet or the outlet Or a steam / water separator, wherein a flow velocity reduction mechanism is provided around the outer cylinder directly above the discharge port.   The flow rate reduction mechanism is composed of a porous ring member attached to the discharge port of the outer cylinder. The porous ring member gives resistance to the steam flowing out from the cooling water flow path, and reduces the flow rate of steam. The steam-water separator according to claim 1, wherein the steam-water separator is one.   The flow velocity reduction mechanism is composed of a porous ring member provided in a direction intersecting the axial direction of the outer cylinder around the outer cylinder of the front-stage steam-water separation unit immediately below the discharge port. The steam-water separator according to claim 1, wherein resistance is provided to the steam flowing out from the cooling water flow path to reduce the flow rate of the steam.   The flow velocity reduction mechanism is configured by forming a region directly above the discharge port of the outer cylinder with a porous cylindrical body and discharging the steam from a steam discharge hole formed in the porous cylindrical body. The steam-water separator according to claim 1, wherein the steam-outflow rate of the steam flowing out from the outlet is reduced.

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