JP7057966B2 - Maintenance method for drainage device - Google Patents

Description

The present invention includes an entrance / exit section where seawater enters and exits, a pit where seawater is stored, a main pipe which connects the entrance / exit section and the pit and has a joint and a pipe, and a sub pipe connected to the pit, and is attached to a seawater utilization facility. The maintenance method of the intake / drainage device that takes prescribed measures for the joint part of the intake / drainage device.

In power plants and factories that use seawater, seawater is used as a heat medium. For example, in a thermal power plant as an example of a power plant, a condenser that condenses steam returning from a power generation turbine is used as a seawater utilization device. In this condenser, seawater is used as a cooling medium. Further, in a city gas factory as an example of a factory, an LNG vaporizer for vaporizing liquefied natural gas (LNG) is provided as a seawater utilization device, and in this LNG vaporizer, seawater is used as a medium for heating. There is.

Patent Document 1 describes a seawater pump that pumps seawater from an intake pit, a seawater header that stores seawater pumped by the seawater pump, and an LNG vaporizer as a seawater utilization device that operates using seawater supplied from the seawater header. A city gas factory equipped with such as is disclosed. Usually, a city gas factory as disclosed in Patent Document 1 is provided with an intake device including the above intake pit, an intake section installed in the sea, and a pipe connecting the seawater pit and the intake section. The seawater taken in from the intake section circulates in the pipe and flows into the intake pit, and the seawater flowing into the intake pit is pumped up by the seawater pump and used.

Here, the piping of the water intake device penetrates the revetment installed between the sea side and the land side and is buried in the ground. Therefore, the ground is shaken by an earthquake or the like, the ground is liquefied and the ground is displaced, or liquefaction occurs in the ground below the shore and on the land side of the shore, which causes earth pressure to act on the shore. If the shore protection moves to the sea side, the pipes may be displaced or an excessive load may be applied to the pipes, which may damage the pipes or the joints connecting the pipes. Therefore, conventionally, by providing a telescopic joint in a part of the main pipe, it is possible to follow the displacement of the ground and the movement of the revetment to some extent.

Japanese Unexamined Patent Publication No. 2014-169609

However, even if it is possible to follow the displacement of the ground and the movement of the revetment to some extent, it is difficult to completely prevent the joint portion from being damaged, so that the damaged joint portion may need to be repaired.

In recent years, the importance of reinforcement measures for existing equipment is increasing, assuming that the amount of displacement of the ground and the amount of movement of the revetment will exceed the permissible range due to an unexpected large-scale earthquake. As a proper reinforcement measure, it may be necessary to reinforce the joint.

However, as mentioned above, since the main pipe of the water intake device penetrates the revetment and is buried in the ground, in order to take measures for the purpose of maintenance of the water intake device such as repair work and reinforcement work of the joint part. Has the problem that it is necessary to expose the main pipe by large-scale civil engineering work, it is difficult to suppress the work cost, and the work takes a long time. Further, such a problem exists not only in the water intake device but also in the drainage device for draining seawater.

The present invention has been made in view of the above circumstances, and is a method for maintaining a drainage device, which can easily take measures such as repair work and reinforcement work of a joint portion for the purpose of maintenance of the drainage device. The purpose is to provide.

The features of the maintenance method of the intake / drainage device according to the present invention for achieving the above object are the entrance / exit section where the seawater enters and exits, the pit which is provided with the pump for pumping the seawater, and the entrance / exit. In an intake / drainage device attached to a seawater utilization facility, the joint is provided with a main pipe connecting the portion and the pit and having a joint portion, and a sub pipe having one end connected to the pit and the other end arranged in the sea. It is a maintenance method of the drainage device that takes measures to reinforce or repair the part.
After performing a flow velocity lowering step in which the seawater is circulated through the sub-pipe and the flow velocity of the seawater flowing through the main pipe is made lower than the flow velocity when the seawater is not circulated through the sub-pipe.
The point is to carry out a measure process for taking measures to reinforce or repair the joint portion from within the main pipe.

According to the above characteristic configuration, a flow velocity reducing step is performed in which seawater is circulated through the auxiliary pipe and the flow velocity of the seawater flowing through the main pipe is made lower than the flow velocity when the seawater is not circulated through the auxiliary pipe. Workers will be able to invade the main pipe while maintaining a state in which seawater can flow in or drain from the pit. Then, a worker enters the main pipe where the flow velocity has decreased, and implements a measure process in which a predetermined measure is taken from the inside of the main pipe to the portion (joint portion) connected by the joint. The flow velocity of the seawater flowing through the main pipe is reduced to a flow velocity at which the operator can take a predetermined measure in the main pipe.

As described above, according to the above-mentioned characteristic configuration, since it is possible to carry out a measure process in which a predetermined measure is taken from the inside of the main pipe to the joint portion, as compared with the case of performing a large-scale civil engineering work for exposing the main pipe. The work cost can be suppressed, and the time required for a predetermined measure can be significantly shortened.

Further, a further characteristic configuration of the maintenance method of the intake / drainage device according to the present invention is that the intake / drainage device includes an intake section as the inlet / outlet section, and seawater into the sub-pipe is provided at the sea-side end portion of the sub-pipe. It is a water intake device equipped with a sea-side water stop lid to prevent the intrusion of water.
The flow velocity lowering step is
The process of removing the sea-side water-stopping lid and the process of removing the sea-side water-stopping lid,
It is a point including a partition wall installation step of installing a partition wall in a communication portion between the pit side end portion of the main pipe and the pit.

According to the above characteristic configuration, the seawater is in a state of flowing into the pit through the main pipe and the sub pipe by performing the sea side water stop lid removal step. After that, by performing the partition wall installation process, the inflow of seawater from the pit into the main pipe is suppressed. Therefore, the measure step can be performed in a state where the flow velocity of the seawater flowing in the main pipe is lower than the flow velocity when the seawater is not circulated in the sub pipe. In this case as well, the flow velocity of the seawater flowing in the main pipe is reduced to a flow velocity at which the operator can take a predetermined measure for the joint portion in the main pipe.

As described above, even in the above-mentioned characteristic configuration, since it is possible to carry out a measure process in which a predetermined measure is taken from the inside of the main pipe to the joint portion, the work cost is compared with the case where a large-scale civil engineering work for exposing the main pipe is required. And the time required to take a predetermined measure can be significantly shortened.

Further, a further characteristic configuration of the maintenance method of the intake / drainage device according to the present invention is that the flow velocity reducing step includes a pit side water stop lid installation step of installing a pit side water stop lid at the pit side end of the sub pipe. ,
Further including a step of removing the pit-side water-stopping lid for removing the pit-side water-stopping lid.
The pit-side water-stopping lid installation step is performed before the sea-side water-stopping lid removal step.
The pit-side water-stopping lid removing step is performed between the sea-side water-stopping lid removing step and the partition wall installation step.

According to this characteristic configuration, by performing the pit side water stop lid installation step before performing the sea side water stop lid removal step, the water pressure acting on the sea side water stop lid installed at the sea side end of the auxiliary pipe. Will become very small, and the seaside water stop lid can be easily removed. Then, by performing the pit side water stop lid removal step between the sea side water stop lid removal step and the partition wall installation step, it is possible to make the seawater flow into the pit through the main pipe and the sub pipe.

It is a top view which shows the water intake device. It is sectional drawing which shows the expansion joint part. It is a flowchart for demonstrating the maintenance method of the intake device which concerns on 1st Embodiment. It is a figure for demonstrating the maintenance method of the intake device which concerns on 1st Embodiment, and is an enlarged view which shows the communication part between a main pipe and an intake pit. It is a figure for demonstrating the maintenance method of the intake device which concerns on 1st Embodiment, and is an enlarged view which shows the sea side end part of the auxiliary pipe. It is a figure for demonstrating the maintenance method of the intake device which concerns on 1st Embodiment, and is an enlarged view which shows the communication part between a main pipe and an intake pit. It is a figure for demonstrating the maintenance method of the water intake device which concerns on 1st Embodiment, and is sectional drawing which shows the expansion joint part. It is a figure for demonstrating the maintenance method of the intake device which concerns on 1st Embodiment, and is an enlarged view which shows the sea side end part of the auxiliary pipe. It is a figure for demonstrating the maintenance method of the water intake device which concerns on 1st Embodiment, and is sectional drawing which shows the expansion joint part.

Hereinafter, with reference to the drawings, in one embodiment of the maintenance method of the intake / drainage device according to the present invention, an embodiment in which a portion (expansion joint portion) provided with an expansion joint of the water intake device shown in FIGS. 1 and 2 is reinforced. As an example, "maintenance method of intake / drainage device" will be described as "maintenance method of intake / drainage device". Note that FIG. 1 is a plan view showing a water intake device, and FIG. 2 is a cross-sectional view showing a telescopic joint portion.

[Water intake device]
First, a schematic configuration of a water intake device 1 attached to an LNG factory or the like as a seawater utilization facility will be described. As shown in FIG. 1, the water intake device 1 connects an intake unit 2 that takes in seawater from the sea, an intake pit 5 that stores seawater, an intake unit 2 and an intake pit 5, and has a pipe 16 and joints 17 and 18. It is provided with a main intake pipe (corresponding to a "main pipe") 15 and a sub intake pipe (corresponding to a "sub pipe") 20 connected to an intake pit 5 and having a pipe 21 and joints 22 and 23.

The water intake unit 2 is provided with a filter (not shown) for preventing the invasion of jellyfish and the like, and is installed in the sea so that the position of the intake port for taking in seawater is lower than the sea level. Further, one end side of the main intake pipe 15 is connected to the intake portion 2.

The intake pit 5 is configured to be partitioned outward by a D-shaped outer peripheral wall 6 in a plan view, and to have a bottom wall supported by a large number of Benot piles. Inside the intake pit 5, the main intake pipe 15 is connected to the intake unit 2, and the sub intake pipe 20 is directly connected to the sea side region S1 and the rectifying wall 7 is connected to the sea side region S1. An inner region S2 is provided which is partitioned with respect to the inner region S2. The rectifying wall 7 is provided with a large number of seawater passages, and is configured to extinguish the waves by allowing the seawater in the seaside region S1 to flow to the inward side region S2 through the seawater passages.

Further, a seawater pump 8 is provided in the intake pit 5. The seawater pump 8 is provided in the upper part of the intake pit 5 in a form in which the suction pipe 9 extends into the seawater in the inner region S2, and is used as a device that uses seawater as a heat medium such as an LNG vaporizer. The seawater header (not shown) that supplies seawater is configured to pump up the seawater taken into the intake pit 5.

Further, in the inner region S2, a plurality of berth screens 10 and a plurality of traveling screens 11 are provided in order to remove large foreign substances (shells and the like) existing in the seawater before being pumped by the seawater pump 8. At the same time, a plurality of corner drop 12s for adjusting the flow of seawater are provided.

In the main intake pipe 15, a plurality of pipes 16 are connected by expansion joints 17 and special joints 18, one end of which is connected to the sea side region S1 of the intake pit 5 and the other end of which is the intake of the intake portion 2. In the connected state, it is buried in the ground through the revetment.

Further, in the sub intake pipe 20, similarly to the main intake pipe 15, a plurality of pipes 21 are connected by expansion joints 22 and special joints 23, and one end side is connected to the sea side region S1 of the intake pit 5. With the other end placed in the sea, it penetrates the revetment and is buried in the ground. The sub-intake pipe 20 is provided with a sea-side water stop lid 24 that closes the pipe mouth at the sea-side end, and a pit-side water stop lid 25 that closes the pipe mouth at the pit-side end. You can do it.

As shown in FIG. 2, the expansion joint 17 in the main intake pipe 15 includes a sleeve pipe 17a, two flanges 17b, two rubber rings 17c, and a plurality of pairs of bolts 17d and nuts 17e for fastening the two flanges 17b. The rubber rings 17c are sandwiched between the inner peripheral surfaces of both ends of the sleeve pipe 17a and the outer peripheral surfaces of the two pipes 16 in the main intake pipe 15, and the two flanges are pressed so as to press the rubber rings 17c. 17b is fastened. Therefore, the pipe 16 can move by a certain amount in the pipe axis direction in a state where the space between the internal space and the external space is sealed by the rubber ring 17c. Although the structure of the special joint 18 in the main intake pipe 15 is not described in detail, a known special joint structure can be adopted.

Since the expansion joint 22 in the sub intake pipe 20 has the same configuration as the expansion joint 17 in the main intake pipe 15, detailed description thereof will be omitted. Further, as for the special joint 23, a known special joint structure can be adopted as in the special joint 18 of the main intake pipe 15.

Next, the procedure of the maintenance method of the water intake device for reinforcing the expansion joint portion of the main water intake pipe 15 in the water intake device 1 will be described below with reference to FIGS. 3 to 9. Note that FIG. 3 is a flowchart illustrating a procedure of a maintenance method of the water intake device according to the first embodiment. 4 to 9 are views for explaining the state of the water intake device 1 in each step in the maintenance method of the water intake device according to the first embodiment, and FIGS. 4, 6 and 8 are FIGS. 1 is an enlarged view of part A, FIGS. 5 and 9 are enlarged views of part B in FIG. 1, and FIG. 7 is a cross-sectional view showing a telescopic joint portion.

First, as shown in FIG. 4, the step of installing the pit-side water stop lid 25 at the intake pit-side end of the sub-intake pipe 20 (pit-side water stop lid installation step) # 1 is performed, and the water intake of the sub-intake pipe 20 is performed. The pipe opening on the pit 5 side is closed to stop the flow of seawater between the intake pit 5 and the inside of the sub intake pipe 20. As a result, the water pressure acting on the sea-side water stop lid 24 becomes very small, and the sea-side water stop lid 24 can be easily removed.

Next, as shown in FIG. 5, a step of removing the sea-side water stop lid 24 installed at the sea-side end of the sub-intake pipe 20 (sea-side water stop lid removal step) # 2 is performed. The water blocking lids 24 and 25 are installed and removed by a crane vessel. Further, it is preferable to perform the net installation work for preventing the invasion of jellyfish into the sub-intake pipe 20 together with the sea-side water stop lid removing step # 2.

After that, as shown in FIG. 6, a step (pit side water stop lid removing step) # 3 of removing the pit side water stop lid 25 installed at the intake pit side end of the sub intake pipe 20 is performed. As a result, seawater flows into the seaside region S1 of the intake pit 5 through the main intake pipe 15 and the sub intake pipe 20. In this state, the flow velocity of the seawater flowing in the main intake pipe 15 is about half or less due to the relationship of the head loss as compared with the flow velocity when the seawater flows only in the main intake pipe 15.

After that, a step of installing a partition wall 30 for partitioning the main intake pipe 15 in a portion S1a (communication portion) that communicates the end of the main intake pipe 15 on the intake pit 5 side and the sea side region S1 of the intake pit 5 (installation of the partition wall). Step) # 4 is performed. As a result, as shown in FIG. 6, the inflow of seawater from the intake pit 5 into the main intake pipe 15 is suppressed, and the flow velocity of the seawater flowing through the main intake pipe 15 is reduced. In the present embodiment, it is preferable that the flow velocity of the seawater in the main intake pipe 15 is 20 cm / sec or less in order for the worker to safely carry out the reinforcement work in the main intake pipe 15. Reduces the flow velocity of seawater flowing in the main intake pipe 15 to 20 cm / sec or less. In the maintenance method of the water intake device according to the present embodiment, the pit side water stop lid installation process # 1, the sea side water stop lid removal process # 2, the pit side water stop lid removal process # 3, and the partition wall installation process # 4 is a flow velocity reducing step.

In this way, the step (measure step) # 5 of performing the reinforcement work as a predetermined measure is carried out in a state where the flow velocity of the seawater flowing in the main intake pipe 15 is reduced. In the present embodiment, as a reinforcing member used for reinforcing the telescopic joint portion, as shown in FIG. 7, the reinforcing work is performed using a square bar 31 having a protrusion 31a in the intermediate portion. Specifically, in the reinforcement work, a diver carries in necessary materials such as a square bar 31 having a neutral buoyancy using an underwater crane to the construction site (that is, the expansion joint portion). Then, underwater welding is performed so that the plurality of square bars 31 are positioned at equal intervals in the circumferential direction of the main intake pipe 15 with the protrusions 31a fitted between the two pipes 16. As a result, as shown in FIG. 7, the expansion joint portion is reinforced from the inside of the main intake pipe 15 by a plurality of square bars 31.

After the measure step # 5 is carried out as described above, the step of removing the partition wall 30 installed in the communication portion S1a (partition wall removal step) # 6 is performed, and as a result, as shown in FIG. Seawater flows into the intake pit 5 through the water pipe 15 and the auxiliary intake pipe 20. After that, the step of installing the sea-side water stop lid 24 at the sea-side end of the sub-intake pipe 20 (sea-side water stop lid installation step) # 7 is performed. As a result, as shown in FIG. 9, the inflow of seawater into the intake pit 5 through the sub intake pipe 20 is stopped, and the seawater flows into the intake pit 5 only through the main intake pipe 15, that is, the original normal state. Return to the state of.

As described above, according to the maintenance method of the water intake device according to the present embodiment, large-scale civil engineering work for exposing the main water intake pipe 15 when performing a measure process for taking measures such as reinforcement for the expansion joint portion. It is possible to take a predetermined measure from the inside of the main intake pipe 15 to the expansion joint portion without requiring the above. Therefore, compared to the case where large-scale civil engineering work is required, the cost required to take measures such as reinforcement work and repair work can be suppressed, and the time required to take the prescribed measures can be significantly shortened. can.

[Another Embodiment]
[1]
In the above embodiment, the maintenance method of the intake / drainage device according to the present invention has been described with reference to specific examples, but the embodiment can be changed as appropriate. For example, in the above embodiment, the embodiment of reinforcing the expansion joint portion of the water intake device 1 has been described as an example as a measure step, but the present invention is not limited to this, and the special joints 18 and 23 are reinforced or the expansion joint is damaged. Work such as repairing 17, 22 and special joints 18, 23 may be performed as a measure process. A telescopic joint, which is a type of joint, connects two pipes in a state where they can be expanded and contracted by a certain amount. It has the advantage of being able to follow. However, since the two pipes are connected in a stretchable state, the pipe may fall off from the telescopic joint or a gap may be created at the joint between the pipe and the telescopic joint depending on the amount of displacement of the ground and the amount of movement of the revetment. If this occurs, the inside and outside of the main intake pipe will be in a state of communication, and there is a risk that sediment will flow into the main intake pipe. Such a problem is more likely to occur in an expansion joint in which two pipes are connected in a stretchable state as compared with a special joint in which two pipes are fixed and connected. It is important to take the above measures to prevent the occurrence of the above problems. Further, in the above embodiment, the embodiment in which the square bar 31 having the protrusion 31a is used as the reinforcing member is shown, but the present invention is not limited to this, and the member used in the measure step is repairing an expansion joint or a special joint. One or more members necessary for reinforcement and members that can be conveyed in the pipe can be appropriately selected. By doing so, the worker can carry in the member necessary for the predetermined measure into the main pipe, and can take the predetermined measure for the joint portion by using the carried-in member.

[2]
Further, in the above embodiment, the mode of reducing the flow velocity of the seawater flowing through the main intake pipe 15 to 20 cm / sec or less has been described as an example, but the speed at which the operator can perform a predetermined work in the main intake pipe 15. If so, it is not particularly limited.

[3]
Further, in the above embodiment, the pit side water stop lid installation step # 1 and the pit side water stop lid removal step # 3 are performed as the flow velocity lowering step, but these two steps are omitted if necessary. Then, the sea-side waterproof lid removal step # 2 and the partition wall installation step # 4 may be performed.

[4]
Further, in the above embodiment, the maintenance method of the water intake device 1 has been described, but it can also be applied as a maintenance method of the drainage device, for example. That is, in a drainage device having a drainage section as an entrance / exit section, a drainage pit in which seawater is stored, a main drainage pipe connecting the drainage section and the drainage pit, and a secondary drainage pipe connected to the drainage pit, seawater is added to the secondary drainage pipe. By reducing the flow velocity of the seawater flowing through the main drainage pipe, the joint portion of the main drainage pipe can be repaired and reinforced from inside the main drainage pipe.

It should be noted that the configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction. The embodiments disclosed in the present specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the object of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used as a maintenance method for an intake / drainage device, which can take measures such as repair work and reinforcement work of a joint portion necessary for maintenance of the intake / drainage device more easily than before.

1 Water intake device 2 Intake part 5 Intake pit 15 Main intake pipe 16 Piping 17 Expansion joint 20 Sub-intake pipe 30 Section wall 31 Square bar (reinforcing member)
S1a communication part

Claims (3)

An inlet / outlet section installed in the sea where seawater enters and exits, a pit equipped with a pump for pumping the seawater and storing the seawater, a main pipe having a joint portion connecting the entrance / exit section and the pit, and one end connected to the pit. It is a maintenance method of the intake / drainage device that has a secondary pipe arranged in the sea at the other end and takes measures to reinforce or repair the joint portion in the intake / drainage device attached to the seawater utilization facility.
After performing a flow velocity lowering step in which the seawater is circulated through the sub-pipe and the flow velocity of the seawater flowing through the main pipe is made lower than the flow velocity when the seawater is not circulated through the sub-pipe.
A maintenance method for an intake / drainage device, which performs a measure step of taking measures to reinforce or repair the joint portion from inside the main pipe. The intake / drainage device is a water intake device including a water intake unit as an inlet / outlet unit and a sea-side water stop lid for preventing the seawater from entering the sub-pipe at the sea-side end of the sub-pipe. hand,
The flow velocity lowering step is
The process of removing the sea-side water-stopping lid and the process of removing the sea-side water-stopping lid,
The maintenance method for an intake / drainage device according to claim 1, further comprising a partition wall installation step of installing a partition wall at a pit-side end of the main pipe and a communication portion between the pit. The flow velocity lowering step includes a pit-side water-stopping lid installation step of installing a pit-side water-stopping lid at the pit-side end of the auxiliary pipe.
Further including a step of removing the pit-side water-stopping lid for removing the pit-side water-stopping lid.
The pit-side water-stopping lid installation step is performed before the sea-side water-stopping lid removal step.
The maintenance method for an intake / drainage device according to claim 2, wherein the pit-side water-stopping lid removing step is performed between the sea-side water-stopping lid removing step and the partition wall installation step.

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