JP2022121142A - Cleaning device and cleaning method for steam-water separator - Google Patents

Abstract

To provide cleaning technique for a steam-water separator which allows for secure removal of dirt, dust, and the like remaining inside the steam-water separator.SOLUTION: A cleaning device 31 comprises a first flange 41 configured to attachably/detachably seal a lower end opening 28 of a constituting unit 20 of a steam-water separator, and a first supply pipe 51 connected to the first flange 41 and supplying a cleaning liquid which is filled inside the constituting unit 20.SELECTED DRAWING: Figure 4

Description

Embodiments of the present invention relate to cleaning techniques for steam separators used in boiling water nuclear reactors.

A steam separator is a device that removes liquid droplets from vapor containing liquid droplets. Steam containing droplets entering the turbine significantly reduces turbine efficiency. Therefore, in a boiling water nuclear reactor, the mixed steam from the reactor core is guided through a steam separator to give a swirling flow, whereby droplets are separated from the outside and steam is separated from the inside by a centrifugal separation action. The steam from which the droplets have been removed is further passed through a steam dryer and led to the turbine, and the separated droplets are returned to the water above the core.

JP 2013-120068 A

When the steam separator is stored in the air during the construction work of the nuclear power plant or during the shutdown period, and there is a concern that dirt, dust, etc. will accumulate inside it, cleaning is performed to remove these. However, the steam separator has a complicated internal structure and is as long as about 5 m in the longitudinal direction. For this reason, when dirt, dust, etc. enter the inside of the steam separator, it is difficult to reliably remove them.

The embodiments of the present invention have been made in consideration of such circumstances, and it is an object of the present invention to provide a technique for cleaning a steam separator that can reliably remove dust, dust, etc. that have accumulated inside. .

In the air-water separator cleaning apparatus according to the embodiment, a first flange detachably seals the lower end opening of the structural unit of the steam-water separator, and the first flange is connected to fill the interior of the structural unit. and a first supply pipe for supplying the cleaning liquid.

The embodiment of the present invention provides a cleaning technique for a steam separator that can reliably remove dust, dust, etc. that have accumulated inside.

A vertical cross-sectional view of a pressure vessel of a boiling water reactor. (A) Vertical sectional view of the steam separator, (B) Horizontal sectional view of the steam separator. The schematic of the longitudinal section in the structural unit of a steam-water separator. The side view of the 1st washing|cleaning apparatus of the steam-water separator which concerns on embodiment. Explanatory drawing of the washing|cleaning method of the steam-water separator by a 1st washing|cleaning apparatus. (A) A vertical cross-sectional view of the second cleaning device of the steam-water separator according to the embodiment, (B) A top view of the second flange of the second cleaning device. Process drawing of the cleaning method of the steam-water separator which concerns on embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to describing a steam separator cleaning apparatus according to an embodiment of the present invention, a steam separator 18 to which the present embodiment is applied and other related structures will be described below with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view of a pressure vessel 12 of a boiling water reactor 10. As shown in FIG.

In a boiling water reactor 10 (BWR), a coolant injected from a water supply nozzle 11 into a pressure vessel 12 passes through a downcomer 14 formed outside a core shroud 13 and inside the pressure vessel 12 to reach the core. enter the bottom. Therefore, the coolant reverses its flow direction, flows upward inside the core shroud 13, absorbs heat from the fuel assemblies 15, and becomes a two-phase flow in which gas phase and liquid phase are mixed.

A steam separator 18 is erected via a plurality of standpipes 17 on a shroud head 16 closing an upper opening of the core shroud 13 . A steam dryer 19 is arranged above the steam separator 18, and droplets in the steam are removed by both of them.

The steam from which moisture has been removed is output from the steam nozzle 40 and supplied to a turbine (not shown). The separated droplets travel along the outside of the shroud head 16, return to the downcomers 14, and are again supplied to the core shroud 13 from the lower part of the core.

FIG. 2(A) is a vertical cross-sectional view of the steam separator 18 (cross-sectional view taken along line AA in FIG. 2(B)). FIG. 2(B) is a horizontal cross-sectional view (cross-sectional view along BB in FIG. 2(A)). The shroud head 16 is removed from the upper opening of the core shroud 13 (FIG. 1) and transported together with the steam separator 18 . The steam separator 18 is composed of a plurality of structural units 20, and as shown in FIG.

FIG. 3 is a schematic view of a longitudinal section of the constituent unit 20 of the steam separator. The illustrated structural unit 20 consists of a standpipe 17 , a first stage 21 and a second stage 22 . Vapor containing droplets input from the lower end opening 28 of the constituent unit 20 is separated into droplets in two stages, the first stage 21 and the second stage 22, and the droplets are removed from the upper end opening 29 of the constituent unit 20. steam is output.

The steam (including droplets) rising up the standpipe 17 from the lower end opening 28 provided in the shroud head 16 turns into a swirling flow after passing through the fixed vanes 23 and enters the first stage 21 . Due to the centrifugal force that accompanies the rotation, the liquid droplets are pressed against the inner peripheral surface of the inner cylinder 25a of the first stage 21 and further rise. It is guided by the gap between the inner peripheral surface of the unit 20 and descends due to gravity, and is discharged to the outside of the constituent unit 20 .

The vapor (including droplets) that has passed through the first stage 21 enters the second stage 22 while maintaining the swirling flow. Then, the centrifugal force accompanying the rotation pushes the liquid droplets against the inner peripheral surface of the inner cylinder 25b of the second stage 22 and further rises. Guided by the gap between the tube 27b and the inner peripheral surface, it descends due to gravity and is discharged to the outside of the structural unit 20. As shown in FIG. The steam that has passed through the second stage 22 is output from the upper end opening 29 of the constituent unit 20 . A third stage may be provided above the second stage 22 .

FIG. 4 is a side view of the first cleaning device 31 of the steam separator according to the embodiment. As described above, the first cleaning device 31 includes the first flange 41 that detachably closes the lower end opening 28 of the constituent unit 20 of the steam separator, and the first flange 41 connected to the constituent unit 20 to fill the interior of the constituent unit 20 . A first supply pipe 51 for supplying the cleaning liquid is provided.

The edge of the first flange 41 is provided with an O-ring 43 that is in close contact with the inner peripheral surface of the standpipe 17 and ensures hermeticity so that the filled cleaning liquid does not leak. Washing water supplied from the lower end opening 28 of the component unit 20 may fill up to its upper end opening 29 (FIG. 3). Therefore, the first flange 41 installed at the lower end opening 28 of the standpipe 17 must have a sealing strength sufficient to withstand such water head pressure.

The first supply pipe 51 has an upper end connected to the first flange 41 and a branch 53 in which an on-off valve 54 is arranged. An external supply source (not shown) for supplying the cleaning liquid is connected to the end of the branch 53 . The branch 53 is also provided with a discharge portion (not shown) for discharging the cleaning liquid filled in the constituent unit 20 to the outside. Furthermore, the lower end 55 of the first supply pipe 51 is configured to abut on the tip of the support member 35 whose height is adjustable.

FIG. 5 is an explanatory diagram of a cleaning method for the steam separator 18 by the first cleaning device 31. FIG. FIG. 5 is an enlarged view of a portion surrounded by a dashed line 30 in FIG. 2(A). The steam separator 18 to be cleaned in this manner is arranged on the work floor 37 via a pedestal 36, and an appropriate work space is secured therein.

Since the shroud head 16 is curved in this manner, the lower end opening 28 of the steam separator 18 has different heights depending on the connecting position of the stand pipe 17 . For this purpose, the first cleaning device 31 is attached to each lower end opening 28 after adjusting the height of the support member 35 . Although the description is omitted, in order to install the first cleaning device 31 and the second cleaning device 32, which will be described later, there is a case where a working scaffold is constructed with pipes or plates.

FIG. 6A is a longitudinal sectional view of the second cleaning device 32 of the steam separator according to the embodiment. In this way, the second cleaning device 32 includes the second flange 42 detachably installed in the upper end opening 29 of the structural unit 20 and the foreign matter ( and a second supply pipe 52 for supplying a gas for blowing off droplets, dirt, dust, etc.).

The second flange 42 is detachably installed in the upper end opening 29 of the structural unit 20 via an intermediate member 46 . The second flange 42 and the upper end opening 29 do not need to be sealed like the first flange 41 and the lower end opening 28, and have the function of ensuring the positional accuracy of the gas injection end 56 of the second supply pipe 52 as described later. .

The injection end 56 of the second supply pipe 52 in the embodiment faces the direction of directly injecting the end position 26 of the inner cylinder 25 located inside the outer cylinder 27 of the structural unit 20 . The shape of the gas injection end 56 is not particularly limited, and any shape may be appropriately adopted as long as it exhibits the function of blowing off foreign matter adhering to the inner peripheral surface of the component unit 20 by injecting gas. The second supply pipe 52 is provided on a sliding bearing 48 provided along the rotationally symmetrical axis of the second flange 42 . Further, a handle 45 that is rotated by an operator and a stopper 47 are fixed to the second supply pipe 52 .

As a result, the worker can press the handle 45 downward and rotate it, so that the gas can be stably jetted to the entire circumference of the end position 26 of the inner cylinder 25 . As a result, remaining dirt, dust, etc. can be discharged to the outside of the structural unit 20 from the end position 26 of the inner cylinder 25 to the gap formed inside the outer cylinder 27 .

Moreover, the fixing positions of the handle 45 and the stopper 47 can be changed with respect to the second supply pipe 52 . As a result, the position of the gas injection end 56 can be adjusted in accordance with the plurality of end positions 26 (26a, 26b) (see FIG. 3) that exist in the longitudinal direction of the structural unit 20. FIG. In addition, by separately preparing the dedicated second supply pipes 52 corresponding to the respective end positions 26 (26a, 26b) without changing the fixing positions of the handle 45 and the stopper 47, the gas injection end 56 can be You can adjust the position.

FIG. 6B is a top view of the second flange 42 of the second cleaning device 32. FIG. As described above, the second flange 42 is provided with the peep hole 44 so that the handle 45 can be operated while confirming the position of the gas injection end 56 .

A method for cleaning the steam separator according to the embodiment will be described based on the process diagram of FIG. 7 (other drawings will be referred to as appropriate). First, as shown in FIG. 4, the lower end opening 28 of the unit 20 constituting the steam separator is sealed with the first flange 41 of the first cleaning device 31 (S11). Then, the cleaning liquid is supplied from the first supply pipe 51 connected to the first flange 41 to fill the inside of the constituent unit 20 (S12).

Next, the cleaning liquid filled in the structural unit 20 is discharged (S13), and then the second flange 42 of the second cleaning device 32 is installed in the upper end opening 29 of the structural unit 20 as shown in FIG. (S14). Then, gas is supplied from the second supply pipe 52 connected to the second flange 42 to blow off the foreign matter adhering to the inner peripheral surface of the constituent unit 20 (S15). Then, the position of the injection end 56 of the second supply pipe 52 is changed, and the gas is injected intensively to the locations where foreign matter tends to adhere or stay (END).

According to the steam separator cleaning apparatus of at least one embodiment described above, by filling the inside of the constituent unit of the steam separator with the cleaning liquid, the dust, dust, etc. remaining inside the unit can be reliably removed. It becomes possible to

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention as well as the scope of the invention described in the claims and equivalents thereof.

For example, in the present embodiment, the inside of the constituent unit 20 is filled with the cleaning liquid by the first cleaning device 31, the cleaning liquid is discharged, and then the gas is injected onto the inner peripheral surface of the configuration unit 20 by the second cleaning device 32. showed that. As another embodiment, there is an example in which the first cleaning device 31 only fills and discharges the cleaning liquid, and the gas injection by the second cleaning device 32 is omitted.

DESCRIPTION OF SYMBOLS 10... Boiling water reactor, 11... Feed water nozzle, 12... Pressure vessel, 13... Core shroud, 14... Downcomer, 15... Fuel assembly, 16... Shroud head, 17... Stand pipe, 18... Steam separator , 19... steam dryer, 20... structural unit, 21... first stage, 22... second stage, 23... fixed blade, 25 (25a, 25b)... inner cylinder, 26 (26a, 26b)... terminal position, 27 (27a, 27b) outer cylinder 28 lower end opening 29 upper end opening 31 first cleaning device (cleaning device) 32 second cleaning device (cleaning device) 35 support member 36 pedestal, 37 Work floor 40 Steam nozzle 41 First flange 42 Second flange 43 O-ring 44 Hole 45 Handle 46 Intermediate member 47 Stopper 48 Sliding bearing 51 First supply pipe, 52 Second supply pipe, 53 Branch, 54 On-off valve, 55 Lower end, 56 Injection end.

Claims (7)

a first flange detachably sealing the lower end opening of the constituent unit of the steam separator;
and a first supply pipe connected to the first flange for supplying a cleaning liquid to fill the inside of the structural unit. In the steam-water separator cleaning device according to claim 1,
In the first supply pipe, the lower end of the first supply pipe opposite to the upper end connected to the first flange is in contact with the tip of a height-adjustable support member. In the steam separator cleaning device according to claim 1 or claim 2,
a second flange detachably installed in the upper end opening of the constituent unit;
a second supply pipe that is connected to the second flange and supplies gas for blowing off foreign matter adhering to the inner peripheral surface of the component unit. In the steam-water separator cleaning device according to claim 3,
A cleaning device for a steam separator, wherein the second supply pipe is rotatably connected to the second flange, and a handle that is rotatably operated by an operator is fixed. In the steam-water separator cleaning device according to claim 4,
A cleaning device for a steam separator, wherein the gas injection end of the second supply pipe is oriented in a direction to directly inject the end position of the inner cylinder located inside the outer cylinder of the structural unit. In the steam-water separator cleaning device according to claim 5,
The second supply pipe is a cleaning device for a steam separator in which the position of the injection end of the gas is adjusted in accordance with the end positions of the plurality of ends existing in the longitudinal direction of the structural unit. a step of sealing the lower end opening of the structural unit of the steam separator with a detachable first flange;
a step of supplying a cleaning liquid from a first supply pipe connected to the first flange and filling the inside of the constituent unit;
A step of installing a detachable second flange at the upper end opening of the structural unit after discharging the cleaning liquid filled in the structural unit;
and a step of supplying gas from a second supply pipe connected to the second flange to blow off foreign matter adhering to the inner peripheral surface of the component unit.

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