JP2005144213A - Method and system for controlling adhesion and growth of marine organism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the concentration of chlorine in seawater discharged into sea at low level while effectively controlling the adhesion and growth of marine organisms, such as shellfishes, in a cooling water system with a chlorine-based chemical when cooling target equipment with seawater. <P>SOLUTION: A cooling water system 28 comprises water intake passages 20A, 20B for supplying cooling water (seawater) to steam condensers 18A, 18B, a discharge passage 22 for discharging the seawater, having passed through the steam condensers 18A, 18B, to sea, and an LNG vaporizer passage 27 for circulating a part of the seawater discharged from the discharge passage 22 to an LNG vaporizer 17. Chemical injection parts 32A-32C are installed in the vicinities of the water intake ports of the water intake passages 20A, 20B and the inlet of the LNG vaporizer passage 27. The chemical injection ports 32A-32C are switched sequentially to inject a sodium hypochlorite solution into the passages sequentially. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and system for suppressing the attachment and growth of marine organisms in a cooling water system for cooling an apparatus such as a condenser using seawater.

In thermal power plants that use seawater as cooling water, shells, etc. are placed inside the intake channel that takes seawater from the ocean and supplies it to the condenser, and the discharge channel that releases the seawater that has passed through the condenser to the ocean. The marine life is easy to adhere. When the adhesion amount of such marine organisms increases, there is a risk of causing problems such as blocking the cooling water flow path and lowering the cooling performance. Therefore, conventionally, as disclosed in, for example, Patent Document 1 and Patent Document 2, a chlorine-based chemical such as a sodium hypochlorite solution or chlorine dioxide is injected into the flow path of the cooling water, thereby In order to prevent the attachment and growth of marine organisms.
JP-A-7-265867 Japanese Patent Laid-Open No. 11-37666

  As mentioned above, seawater after being used as cooling water in thermal power plants is released to the sea, but for environmental conservation, the chlorine concentration (residual chlorine concentration) contained in the discharged water to the sea is constant. It is required to be below the agreed value. Therefore, the injection amount of the chlorinated chemical for removing marine organisms must be limited so as to satisfy the above requirements, and it is not easy to obtain a sufficient removal effect within the limits.

  The present invention has been made in view of the above points, and when cooling a facility to be cooled with seawater, adhesion and growth of marine organisms are effectively suppressed with a chlorine-based chemical in a flow path constituting the cooling water system. On the other hand, an object is to make it possible to keep the chlorine concentration in the seawater released to the sea low.

In order to achieve the above object, the invention described in claim 1 is for taking seawater from the sea as cooling water and supplying it to the facility to be cooled, and discharging the seawater after passing through the facility to be cooled to the sea. A method for suppressing the attachment and growth of marine organisms in the cooling water system of
A drug injection unit for injecting a chlorine-based drug is provided in at least two of the plurality of channels constituting the cooling water system, and the drug injection selected by sequentially switching from among the drug injection units It is characterized by injecting a chlorinated chemical into the corresponding flow path by the part.

  According to the present invention, a drug injection part is provided in each of the plurality of cooling water flow paths, and a chlorinated drug is injected into the corresponding flow path by the drug injection part selected by switching sequentially from among the drug injection parts. For this reason, high residual chlorine concentration can be obtained in the flow path into which the chlorine-based chemical is injected, and marine organisms can be effectively prevented from attaching and growing. Moreover, since the flow paths into which the chlorinated chemicals are injected are sequentially switched, marine organisms attached to the respective flow paths are sequentially removed. On the other hand, the seawater released into the sea includes seawater in a channel into which no chlorine-based chemicals are injected, so that the chlorine component is diluted and the residual chlorine concentration is kept low. Thus, according to the present invention, it is possible to effectively suppress the adhesion and growth of marine organisms in the cooling water system while keeping the residual chlorine concentration of seawater released to the sea low.

  The invention described in claim 2 is characterized in that, in the method according to claim 1, sodium hypochlorite is injected as the chlorinated drug.

The invention described in claim 3 is the method according to claim 1 or 2, wherein the cooling water system includes a plurality of intake passages for sending seawater taken from the sea to the plurality of facilities to be cooled, respectively. And a water discharge channel for discharging seawater that has passed through the facility to be cooled to the sea,
The medicine injection part is provided in the vicinity of each water intake port of the plurality of water intake channels.

Moreover, the invention described in claim 4 is the method according to any one of claims 1 to 3, wherein the cooling target facility is a facility provided in a liquefied natural gas (LNG) thermal power plant. , An LNG vaporizer flow path for circulating the seawater flowing through the discharge channel to the LNG vaporizer is provided,
At least one of the drug injection portions is provided in the LNG vaporizer flow path.

Moreover, in the cooling water system for taking in the seawater as the cooling water from the sea and supplying it to the equipment to be cooled, and discharging the seawater after passing through the equipment to be cooled to the sea. A system for suppressing the attachment and growth of marine organisms,
A drug injection part for injecting a chlorine-based drug, provided in at least two channels among the plurality of channels constituting the cooling water system;
Control means for injecting a chlorine-based drug into the corresponding flow path by a drug injection unit selected by switching sequentially from the plurality of drug injection units.

  ADVANTAGE OF THE INVENTION According to this invention, adhesion and growth of marine organisms, such as a shellfish, can be effectively suppressed within a cooling water system | strain, suppressing the residual chlorine density | concentration of the seawater discharge | released to the sea low.

  FIG. 1 is a schematic plan view of a thermal power plant 10 according to an embodiment of the present invention. As shown in the figure, the thermal power plant 10 is constructed on a site facing the sea 2. The thermal power plant 10 is provided with various facilities such as a fuel storage facility 12, an LNG tank 14, a power generation facility 16, an LNG vaporizer 17, and the like. In the present embodiment, the two condensers 18A and 18B provided in the power generation facility 16 are cooled with seawater, and intake water for taking seawater from the sea 2 and supplying it to the condensers 18A and 18B, respectively. Roads 20A and 20B and a water discharge path 22 for releasing seawater that has passed through the condensers 18A and 18B to the sea 2 are installed. Seawater is taken in from the inlets 24A and 24B at the ends of the intake channels 20A and 20B, flows through the intake channels 20A and 20B, passes through the condensers 18A and 18B, respectively, and then passes through the discharge channel 22 common to both systems. It passes through the water outlet 26 at its tip and is discharged into the sea 2.

  In the present embodiment, the LNG vaporizer flow path 27 for circulating a part of the seawater flowing through the water discharge path 22 to the LNG vaporizer 17 is branched from the water discharge path 22. The LNG vaporizer 17 vaporizes LNG by the heat of seawater supplied from the LNG vaporizer flow path 27. Thus, by vaporizing LNG with seawater after being used as cooling water, the seawater warmed by the condenser 18 can be cooled and then released into the sea 2.

  As described above, since seawater flows through the intake channel 20, the discharge channel 22, and the LNG vaporizer channel 27, marine organisms such as shellfish are easily attached and propagated in the channel. If a large amount of marine organisms adhere to the flow path, the flow performance may be reduced because the flow path is blocked and a sufficient flow rate cannot be obtained. In particular, with regard to the intake channels 20A and 20B, the intake ports 24A and 24B are provided offshore so as to be able to take in seawater having a low water temperature. Susceptible to. The LNG vaporizer flow path 27 through which the seawater warmed by the condenser 18 flows is in a state where marine organisms are easy to breed.

  Therefore, in the present embodiment, the sodium hypochlorite solution is injected as a chlorinated chemical into the vicinity of the intake port 24 of the intake channel 20 and the vicinity of the inlet of the LNG vaporizer channel 27, thereby allowing the intake channel 20 to be released. In the water channel 22 and the inner wall surface of the LNG vaporizer channel 27, adhesion and growth of marine organisms such as shellfish are suppressed. However, it is not limited to sodium hypochlorite, and other chlorinated chemicals such as chlorine dioxide may be used.

  FIG. 2 schematically shows a cooling water system 28 including intake channels 20 </ b> A and 20 </ b> B, a discharge channel 22, and an LNG vaporizer channel 27. As shown in the figure, seawater pumps 30A and 30B are provided at the connection portions between the condenser 18 and the intake channels 20A and 20B, respectively, and seawater is taken in by the seawater pumps 30A and 30B. To the intake channels 20A and 20B.

  In the vicinity of the water intakes 24A and 24B of the water intake channels 20A and 20B, drug injection portions 32A and 32B are provided, respectively. Further, a drug injection part 32C is provided in the vicinity of the inlet of the LNG vaporizer flow path 27. The drug injection units 32A to 32C have the same configuration, and are collectively referred to as the drug injection unit 32.

  In the vicinity of the water outlet 26 of the water discharge channel 22, a residual chlorine concentration meter 34 for detecting the residual chlorine concentration in the seawater discharged to the sea 2 is provided. The detection signal from the residual chlorine concentration meter 34 is sent wirelessly or by wire to a monitoring device provided on land.

  FIG. 3 shows a detailed configuration of the drug injection unit 32. As shown in the figure, the drug injection section 32 includes an injection pipe 40 having an injection port 41 inside the intake channel 20, a drug supply tank 42 for supplying a sodium hypochlorite solution to the injection pipe 40, and a water injection path 40. The opening / closing of the valve 44 is controlled by a control device 46 common to the drug injection parts 32A to 32C. In the example shown in FIG. 3, the tip of the injection tube 40 is bent toward the downstream side of the seawater, and an injection port 41 is provided at the tip. In addition, as shown in FIG. 4, you may comprise so that the cross section of the front-end | tip part of the injection tube 40 may spread toward the injection port 41 gradually. Further, as shown in FIG. 5, a hole provided on the downstream side surface may be used as the injection port 41 without bending the injection tube 40. Thus, various structures can be considered as the injection port 41.

  The injection pipe 40 is preferably attached along the wall surface so that the residual chlorine concentration in the vicinity of the wall surface of the intake channel 20 and the LNG vaporizer channel 27 is increased. In that case, since sludge accumulates in the bottom part of the intake channel 20, it shall be attached along a side part or an upper part. A plurality of injection tubes 40 may be provided.

  FIGS. 6A to 6C show temporal changes in the open / closed state of the valve 44 of the drug injection sections 32A to 32C controlled by the control device 46 (that is, the on / off state of drug injection). As shown in the figure, in this embodiment, sodium hypochlorite is selected from any one of the drug injection parts 32 selected by sequentially switching the drug injection parts 32A, 32B, 32C provided at three locations of the cooling water system 28. The solution is being injected.

  FIG. 7 shows, for example, the distribution of residual chlorine concentration in each part of the cooling water system 28 in a state where a sodium hypochlorite solution is being injected from a drug injection part 32A provided in the intake channel 20A. As indicated by the solid line I in the figure, when the sodium hypochlorite solution is injected from the drug injection portion 32A, the residual chlorine concentration at the intake port 24A of the intake channel 20A is increased, and this concentration decreases downstream. It gradually decreases as you go. On the other hand, since the sodium hypochlorite solution is not injected into the intake channel 20B, the residual chlorine concentration is close to zero in the entire section as indicated by the solid line II in FIG. The seawater flowing through these intake channels 20A and 20B passes through the condensers 18A and 18B, and then merges into one discharge channel 22. For this reason, as shown by the solid line III in the figure, the chlorine in the seawater is diluted at the inlet portion of the discharge channel 22B, the residual chlorine concentration is reduced to about half of the intake channel 20A, and further toward the discharge port 26. It is gradually decreasing.

  7 indicates the residual chlorine concentration of the seawater released from the outlet 26 to the sea 2 while continuously injecting the sodium hypochlorite solution from both the drug injection parts 32A and 32B. The residual chlorine concentration distribution of intake channel 20A, 20B in the case of restraining to the same extent as embodiment is shown. As can be seen by comparing the broken line IV with the solid line I, in this embodiment, the residual chlorine concentration in the intake channels 20A, 20B is continuously measured from both the chemical injection parts 32A, 32B. The amount of residual seawater released into the sea 2 while securing a value close to twice that when injecting water (that is, using a value almost twice as the injection amount or concentration of sodium hypochlorite solution) The chlorine concentration can be suppressed to the same level.

  As described above, according to the present embodiment, by sequentially switching the drug injection parts 32A to 32C and injecting the sodium hypochlorite solution, the residual chlorine concentration in the intake channels 20A and 20B is increased, and shellfish and the like The residual chlorine concentration of the seawater released to the sea 2 can be kept low while effectively suppressing the adhesion and growth of marine organisms.

  Further, in this embodiment, since the warmed seawater flows, the sodium chlorite solution is also injected into the inlet portion of the LNG vaporizer flow path 27 where marine organisms such as algae and bacteria are easy to breed. Also in the vaporizer channel 27, the adhesion and growth of marine organisms can be effectively suppressed. Moreover, as described above, the sodium hypochlorite is fed from any of the drug injection parts 32 while sequentially switching the three drug injection parts 32A to 32C including the drug injection part 32C provided in the LNG vaporizer flow path 27. Since the solution is injected, it is possible to keep the residual chlorine concentration of the seawater released to the sea 2 low while increasing the residual chlorine concentration of the LNG vaporizer flow path 27.

  In the above embodiment, the LNG vaporizer flow path 27 is also provided with the drug injection part 32C. However, when the LNG vaporizer flow path 27 is not provided with the drug injection part 32, the LNG vaporizer flow path 27 is provided. When 27 itself does not exist, what is necessary is just to inject | pour a sodium hypochlorite solution by switching the chemical injection part 32A, 32B of intake channel 20A, 20B alternately. In addition, the number of intake channels 20 is not limited to two, and three or more systems may be provided. In that case, drug injection units 32 are provided in each system, and these are sequentially switched to hypochlorous acid. A sodium solution may be injected. In addition, when only one system of the intake channel 20 is provided, the drug injection unit 32 is provided in the intake channel 20 and the LNG vaporizer channel 27, and they are alternately switched to inject the sodium hypochlorite solution. Good. In short, at least two flow paths constituting the cooling water system are each provided with a drug injection part for injecting a chlorine-based drug, and the drug injection parts are sequentially switched to make a chlorine-based drug such as a sodium hypochlorite solution. If it is the structure which inject | pours, it is contained in the range of this invention.

  In the above embodiment, the condenser of the thermal power plant is cooled as the equipment to be cooled. However, the present invention is not limited to the condenser and is widely applied when cooling various equipment using seawater. Is possible.

1 is a schematic plan view of a thermal power plant according to an embodiment of the present invention. The cooling water system which consists of a water intake channel, a water discharge channel, and a LNG vaporizer flow path is shown typically. It is a figure which shows the detailed structure of a chemical | medical agent injection | pouring part. It is a figure which shows the structural example of the injection port of an injection tube. It is a figure which shows another structural example of the injection inlet of an injection tube. FIGS. 6A to 6C are diagrams showing temporal changes in the open / closed states of the valves of the three drug injection units 32A to 32C (that is, the on / off states of drug injection), respectively. It is a figure which shows distribution of the residual chlorine concentration of each part of a cooling water system | strain in the state which inject | pours the sodium hypochlorite solution from the chemical | medical agent injection | pouring part 32A provided in the intake channel 20A.

Explanation of symbols

2 Sea 10 Thermal power plant 17 LNG vaporizer 18A, 18B Condenser 20A, 20B Intake channel 22 Discharge channel 24A, 24B Intake port 26 Discharge port 27 LNG vaporizer channel 28 Cooling water system 30A, 30B Seawater pump 32 (32A , 32B, 32C) Drug injection part 40 Injection pipe 41 Inlet 42 Drug supply tank 44 Valve 46 Control device

Claims (5)

This is a method for suppressing the adhesion and growth of marine organisms in the cooling water system for taking seawater from the sea as the cooling water and supplying it to the equipment to be cooled and discharging the seawater that has passed through this equipment to the sea. And
A drug injection unit for injecting a chlorine-based drug is provided in at least two of the plurality of channels constituting the cooling water system, and the drug injection selected by sequentially switching from among the drug injection units A method comprising injecting a chlorinated drug into a corresponding flow path by a section.   The method according to claim 1, wherein sodium hypochlorite is injected as the chlorinated drug. The cooling water system includes a plurality of intake channels for sending seawater taken from the sea to the plurality of facilities to be cooled, and a water discharge channel for releasing seawater that has passed through the facilities to be cooled to the sea. And
The method according to claim 1 or 2, wherein the medicine injection part is provided in the vicinity of each water intake port of the plurality of water intake channels. The facility to be cooled is a facility provided in a liquefied natural gas (LNG) thermal power plant, and is provided with an LNG vaporizer flow path for circulating seawater flowing through the water discharge channel to the LNG vaporizer,
The method according to any one of claims 1 to 3, wherein at least one drug injection part is provided in the LNG vaporizer flow path. It is a system that suppresses the adhesion and growth of marine organisms in the cooling water system for taking seawater from the sea as the cooling water and supplying it to the equipment to be cooled, and releasing the seawater that has passed through this equipment to the sea. And
A drug injection part for injecting a chlorine-based drug, provided in at least two channels among the plurality of channels constituting the cooling water system;
A control means for injecting a chlorinated drug into a corresponding flow path by a drug injection unit selected by switching sequentially from the plurality of drug injection units.

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