SAMPLING SYSTEM AND SAMPLING PROCEDURES

Abstract

Sampling system (6; 6') for sampling cooling water flowing through a discharge line (8) extending from a condenser (4) to a sea, wherein the sampling system (6; 6') is characterized by: a bypass line (11) which branches off from the discharge line (8) and connects to the discharge line (8); two shut-off valves (12, 13) in the bypass line (11); a sampling line (14) which branches off from the bypass line (11) between the two shut-off valves (12, 13); a vent line (15) which branches off from the bypass line (11) between the two shut-off valves (12, 13); a sampling valve (16) in the sampling line (14); and a vent valve (17) in the vent line (15); an additional water line (21) which is connected to the bypass line (11); an additional water valve (22) in the additional water line (21); an actuating device (23) which issues a command signal (S11) for a command to take a sample of the cooling water; and a control unit (24) which controls the two shut-off valves (12, 13), the vent valve (17), the sampling valve (16) and the auxiliary water valve (22) with the command signal (S11) from the actuating device (23) as trigger, wherein the two shut-off valves (12, 13) are motorized on / off valves of the normally open type, whereas the vent valve (17), the sampling valve (16) and the auxiliary water valve (22) are motorized on / off valves of the normally closed type, and The control unit (24) then, when the command signal (S11) is entered by the actuating device (23), sequentially instructs as follows: Closing the two shut-off valves (12, 13), Opening the sampling valve (16) and the venting valve (17), Closing the sampling valve (16), Opening the auxiliary water valve (22), Closing the auxiliary water valve (22), Closing the vent valve (17) and Opening the two shut-off valves (12, 13).

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present invention relates to a sampling system and a sampling method for cooling water used in a condenser and discharged into a sea. 2. Description of the related area

[0002] In a power plant that uses seawater as cooling water, marine organisms deposited on the inner wall of a cooling water piping can act as a resistance that may reduce cooling efficiency. Therefore, an inhibitor is generally added to the cooling water to limit the deposition and spread of marine organisms on the inner wall of the cooling water piping (see JP 2018 - 151 263 A).

[0003] CN 2 05 719 639 U describes a static online sampling device with an inlet and outlet connected via a main line on which a first valve is mounted. The ends of the first valve are additionally connected by a bypass line on which a second and third valve, a sampling valve, and a pressure relief unit are mounted. A delayed solenoid valve in the bypass line opens only when the first valve is closed and closes automatically after a specified time. A pressure sensor in the main line measures the line pressure and controls the solenoid valve.

[0004] EP 0 047 533 A1 relates to an arrangement for taking liquid samples from a pipeline with a pulsating liquid flow. It comprises a bypass line connecting a section with higher pressure to a section with lower pressure. This bypass line contains a chamber with an outlet through which the sample can be taken. State of the art document / Patent document

[0005] Patent document 1: JP 2018 - 151 263 A

[0006] Since the cooling water to which the inhibitor has been added is used in a heat exchanger, such as a condenser, and then discharged into the sea, it is necessary to accurately measure the residual concentration of the inhibitor in the cooling water by taking samples and to confirm, before discharge, that the cooling water does not affect the environment. The discharge line for conveying the cooling water used in the condenser to the sea is often buried underground and may run through pipes at a level higher than the tide mark (e.g., the sea level at high tide). In this case, the flowing cooling water is drawn in by gravity, resulting in a vacuum inside the discharge line. To extract a sample of the cooling water from the discharge line under vacuum, a large device, such as a vacuum pump, is generally required.

[0007] One object of the present invention is to provide a sampling system and a sampling method with which samples of cooling water can be taken from a delivery line under negative pressure with a simple configuration and without the use of a large device. SUMMARY OF THE INVENTION

[0008] To solve the aforementioned problem, according to the present invention, a sampling system for taking samples of cooling water flowing through a discharge line extending from a condenser to a sea is provided, wherein the sampling system comprises: a bypass line branching off from and connecting to the discharge line; two shut-off valves provided in the bypass line; a sampling line branching off from the bypass line between the two shut-off valves; a vent line branching off from the bypass line between the two shut-off valves; a sampling valve provided in the sampling line; and a vent valve provided in the vent line.The sampling system also includes an auxiliary water line connected to the bypass line, an auxiliary water valve provided in the auxiliary water line, an actuating device that issues a command signal for a command to sample the cooling water; and a control unit that controls the two shut-off valves, the vent valve, the sampling valve and the auxiliary water valve with the command signal from the actuating device as the trigger, wherein the two shut-off valves are motorized on / off valves of the normally open type, whereas the vent valve, the sampling valve and the auxiliary water valve are motorized on / off valves of the normally closed type.When the command signal is entered from the actuating device, the control unit sequentially instructs the following: closing the two shut-off valves, opening the sampling valve and the vent valve, closing the sampling valve, opening the auxiliary water valve, closing the auxiliary water valve, closing the vent valve and opening the two shut-off valves.

[0009] According to the present invention, samples of cooling water can be taken from a delivery line under negative pressure with a simple configuration and without using a large device. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic diagram of a power plant to which a sampling system according to a first embodiment of the present invention is applied; Fig. Figure 2 is a schematic diagram of the sampling system according to the first embodiment of the present invention; Fig. Figure 3 is a schematic diagram illustrating the positional relationship of the sampling system and a delivery line according to the first embodiment of the present invention; Fig. Figure 4 is a schematic diagram of a sampling system according to a second embodiment of the present invention; Fig. 5 is a timing diagram illustrating the procedure of a valve control according to the second embodiment of the present invention; and Fig. Figure 6 is a schematic diagram illustrating the configuration of an inlet of a bypass line of a sampling system according to a third embodiment of the present invention and its surroundings. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0010] Embodiments of the present invention are described below with reference to the drawings. First embodiment power plant

[0011] Fig. Figure 1 is a schematic diagram of a power plant to which a sampling system according to a first embodiment of the present invention is applied. The figure illustrates a steam power plant (a thermal power plant) in which a steam turbine is driven by steam generated in a boiler, and a generator is driven by the steam turbine. It should be noted that the sampling system according to the present invention is broadly applicable to plants that have a condenser and is also applicable to combined cycle power plants, nuclear power plants, and the like.

[0012] The plant shown in the figure comprises a boiler 1, a steam turbine 2, a generator 3, a condenser 4, a feedwater pump 5, and a sampling system 6. In this plant, high-temperature, high-pressure steam generated by the boiler 1 is supplied to the steam turbine 2, which is driven by the steam. The generator 3 is driven by the steam turbine 2, thus producing electrical power. Exhaust steam, having driven the steam turbine 2, is supplied to the condenser 4. This exhaust steam is cooled by cooling water (seawater) to condense in the condenser 4 and is then supplied by the feedwater pump 5 to the boiler 1 to become steam again, which is then supplied to the steam turbine 2.

[0013] Seawater, pumped from the sea by an inlet pump (not illustrated), is supplied to the condenser 4 as cooling water via an inlet line 7. An inhibitor (e.g., an oxidation inhibitor such as chlorine) to limit the adhesion and spread of marine organisms to the inner wall surfaces of any piping carrying cooling water is added to the cooling water flowing through the inlet line 7. The cooling water, having cooled the steam in the condenser 4, is discharged to the sea via a discharge line 8. The discharge line 8 runs from the condenser 4 to the sea, and its tip opening forms a discharge port 9 for releasing the cooling water. The length of the discharge line 8 varies according to the distance between the condenser 4 and the sea. The discharge port 9 of the discharge line 8 terminates at or in the sea.At least part of the discharge line 8 is located at a position higher than the flood level and the discharge opening 9, and the principle of a siphon is used to provide a transport force for conveying the cooling water from the condenser 4 to the discharge opening 9. Therefore, part of the inside of the discharge line 8 is located in a negative pressure environment.

[0014] The aforementioned sampling system 6 is provided in the discharge line 8. The residual concentration of the inhibitor in the cooling water, from which a sample is taken by sampling system 6, is measured by a test person, and it is checked whether the residual concentration of the inhibitor in the cooling water, which is to be discharged into the sea, has been sufficiently reduced or not. -Sample collection system-

[0015] Fig. Figure 2 is a schematic diagram of the sampling system according to the first embodiment of the present invention and Fig. Figure 3 is a schematic diagram illustrating the positional relationship between the sampling system and the discharge line. The sampling system 6, shown in the figures, is a system for taking samples of the cooling water flowing through the discharge line 8 and includes a bypass line 11, two shut-off valves 12 and 13, a sampling line 14, a vent line 15, a sampling valve 16, and a vent valve 17. • Bypass line 11

[0016] Bypass line 11 is a culvert that branches off from discharge line 8 and reconnects to it. Bypass line 11 is located at a higher position than the flood level (e.g., sea level at high tide). The internal diameter (cross-sectional area) of bypass line 11 is smaller than that of discharge line 8.

[0017] An outlet 11b (a connecting section to the discharge line 8) of the bypass line 11 is located on the downstream side with respect to the flow direction of the discharge line 8, compared to an inlet 11a (a branch from the discharge line 8) of the bypass line 11. The inlet 11a and the outlet 11b of the bypass line 11 are located at a water-filled section (the section where no dead air space is created) of the discharge line 8. A differential pressure, corresponding to a pressure drop in the discharge line 8, is generated between the inlet 11a and the outlet 11b, and the pressure at the outlet 11b is lower than at the inlet 11a by the differential pressure. Cooling water is drawn from the discharge line 8 into the bypass line 11 using this differential pressure and can flow through the bypass line 11.Therefore, an interval between inlet 11a and outlet 11b should be ensured to generate the differential pressure necessary to allow the cooling water to flow from the discharge line 8 into the bypass line 11. However, it should be noted that if the length of the bypass line 11 is greater than necessary, the pressure drop within the bypass line 11 itself will increase, and therefore the interval between inlet 11a and outlet 11b should be set short in the range where the required differential pressure can be maintained.

[0018] Additionally, as in Fig. As shown in Figure 3, the bypass line 11 descends from the inlet 11a (in the present embodiment at an angle) downwards, runs parallel to the discharge line 8 for a predetermined distance, and then rises (in the present embodiment at an angle) upwards to the outlet 11b. In other words, the bypass line 11 is formed in a U-shape by the downward section 11c from the inlet 11a, the upward section 11d to the outlet 11b, and a horizontal section 11e connecting the downward section 11c and the upward section 11d, and is arranged at a lower position relative to the discharge line 8. The downward section 11c and the upward section 11d are shaped such that they have a monotonically decreasing height as they approach the horizontal section 11e and, in the present embodiment, are in the form of a straight line. The descent section 11c and the ascent section 11d can be vertical.The horizontal section 11e is a piping in the form of straight lines that connects the lower ends of the drop section 11c with the rise section 11d. • Shut-off valves 12 and 13

[0019] The shut-off valves 12 and 13 are provided in the bypass line 11. Of the shut-off valves 12 and 13, the one located on the upstream side with respect to the flow direction of the cooling water in the bypass line 11 is shut-off valve 12, and the one located on the downstream side is shut-off valve 13. The shut-off valves 12 and 13 are, for example, manually operated valves that are opened and closed by manual handles. The shut-off valves 12 and 13 can also be manually operated valves that are opened and closed by actuators. In the present embodiment, shut-off valve 12 is arranged in the downstream section 11c of the bypass line 11, whereas shut-off valve 13 is arranged in the upstream section 11d.It should be noted, however, that the arrangement of the shut-off valves 12 and 13 with respect to the bypass line 11 can be modified in such a way that the channel volume of the bypass line 11 between the shut-off valves 12 and 13 is equal to or greater than the volume of cooling water from which samples are to be taken. For example, one or both shut-off valves 12 and 13 can be arranged in the horizontal section 11e of the bypass line 11. • Sampling line 14 • Sampling valve 16

[0020] The sampling line 14 branches off from the bypass line 11 between the shut-off valves 12 and 13. In the present embodiment, the sampling line 14 branches off from the horizontal section 11e of the bypass line 11 and runs vertically downwards. The aforementioned sampling valve 16 is provided in the sampling line 14. Similar to the shut-off valves 12 and 13, the sampling valve 16 is a manually operated valve, which is opened and closed by manually operating a handle; alternatively, a manually operated valve, which is opened and closed by an actuator, can be used. • Vent line 15 • Vent valve 17

[0021] Similar to the sampling line 14, the vent line 15 branches off from the bypass line 11 between the shut-off valves 12 and 13. In the present embodiment, the vent line 15 branches off from the horizontal section 11e of the bypass line 11 and runs vertically upwards. While in Fig. Figure 2 illustrates a configuration in which the vent line 15 branches off from the bypass line 11 at a position on the upstream side of the sampling line 14. The positional relationship between the sampling line 14 and the vent line 15 can be reversed. The aforementioned vent valve 17 is provided in the vent line 15. Similar to the shut-off valves 12 and 13, the vent valve 17 is a manually operated type, opened and closed by manually operating a handle. Alternatively, a manually operated type, opened and closed by an actuator, can be used. -Sample collection procedure-

[0022] A method for taking samples of the cooling water flowing through the discharge line 8 is described, using the sampling system 6, which is described with reference to Fig. 2 and Fig. 3 is described. Fig. 2. The valves represented by white-filled symbols are in an open state, while the valves represented by black-filled symbols are in a closed state. If no sample of the cooling water is taken, as in Fig. As shown in Figure 2, shut-off valves 12 and 13 are open (fully open), and sampling valve 16 and vent valve 17 are closed (fully closed), causing the cooling water to flow through bypass line 11. As described above, some of the cooling water is drawn into bypass line 11 by the differential pressure between inlet 11a and outlet 11b, creating a flow of cooling water in bypass line 11.

[0023] Then, when a cooling water sample is taken, the two shut-off valves 12 and 13 are closed (fully closed), and the sampling valve 16 and the vent valve 17 are opened. First, since the shut-off valves 12 and 13 are closed, the channel between the shut-off valves 12 and 13 of the bypass line 11 is isolated from the discharge line 8, and the cooling water between the shut-off valves 12 and 13 of the bypass line 11 is sealed. Then, a cooling water sampling bottle (not shown) is placed on the underside of an open end of the sampling line 14, and the sampling valve 16 is opened. As a result, the cooling water, which is sealed in the bypass line 11 between the shut-off valves 12 and 13, is discharged from the sampling line 14 and the cooling water is recovered in the sampling bottle (sampling).In this case, since the vent valve 17 is open, air flows via the vent line 15 into the bypass line 11 between the shut-off valves 12 and 13, and the discharge of cooling water from the sampling line 14 is smoothed.

[0024] Once the cooling water sampling is complete, the sampling valve 16 and the vent valve 17 are closed, and the shut-off valves 12 and 13 are opened, allowing the cooling water to return to the bypass line 11. For example, the sampling valve 16 and the vent valve 17 are initially closed. At this point, air accumulates in the bypass line 11 between the shut-off valves 12 and 13. However, because the bypass line 11 is located lower than the discharge line 8, opening the shut-off valves 12 and 13 results in the air accumulated in the bypass line 11 between the shut-off valves 12 and 13 being released into the discharge line 8 due to the difference in specific density between the air and the cooling water.As a result, the cooling water from the discharge line 8 flows into the bypass line 11 and a flow of cooling water is formed again in the bypass line 11.

[0025] Then, when the opportunity arises to take another sample of the cooling water, the procedure described above is repeated to take a sample of the cooling water. -Effects-

[0026] (1) As described above, according to the present embodiment, which merely connects the bypass line 11 to the discharge line 8 and provides the sampling line 14, the vent line 15 and some valves, samples of cooling water can be taken from the discharge line 8 under vacuum without using a large device such as a vacuum pump. In addition, the sampling system 6, due to its simple configuration, is easily applicable to an existing system.

[0027] It should be noted that a merit of the present embodiment is that the inlet 11a and the outlet 11b of the bypass line 11 are thus located at a higher position than the flood level, and that samples of cooling water can be taken even from a channel under negative pressure in the discharge line 8. Furthermore, as things stand, even if there is positive pressure inside the discharge line 8, the configuration of the sampling system 6 can still be used. In this case as well, samples of the cooling water flowing through the discharge line 8 can, of course, be taken by the sampling system 6.

[0028] (2) Since the bypass line 11 is located at a lower position than the discharge line 8, after a cooling water sample has been taken, any air that has accumulated in the bypass line 11 can be gently discharged into the discharge line 8 due to the difference in specific density between the air and the cooling water. As a result, after sampling, cooling water is introduced into the bypass line 11, and a flow of cooling water within the bypass line 11 can be easily restored without being obstructed by residual air. Therefore, a cooling water sample can be easily taken repeatedly as often as necessary using a similar procedure. Second embodiment

[0029] Fig. Figure 4 is a schematic diagram of a sampling system according to a second embodiment of the present invention. The present embodiment differs from the first embodiment in that, while in the first embodiment samples of cooling water are taken by manually actuating each valve, in the present embodiment the sampling process is semi-automated by controlling the actuation of each valve by a control unit. -Configuration-

[0030] A sampling system 6' in the present embodiment is configured by adding an auxiliary water line 21, an auxiliary water valve 22, an actuating device 23, and a control unit 24 to the sampling system 6 according to the first embodiment. The auxiliary water line 21 is a pipe connected to the bypass line 11, and the auxiliary water valve 22 is provided in the auxiliary water line 21. A foot end (an end section on the side opposite a connecting section for connection to the bypass line 11) of the auxiliary water line 21 is, for example, connected to a pump. The pump connected to the foot end of the auxiliary water line 21 can be a dedicated pump, and in addition, the feed water pump 5, which is located in Fig. Figure 1 shows an inlet pump used to pump seawater as cooling water. Instead of connecting the end of the auxiliary water line 21 to the pump, the end of the auxiliary water line 21 can be connected to a water storage tank (not shown) located at a higher position than the discharge line 8. Such a configuration results in the upstream side (the side opposite the bypass line 11) of the auxiliary water valve 22 having a higher pressure than the downstream side (the side of the bypass line 11).

[0031] The actuating device 23 is, for example, an operating switch that outputs a command signal S11 for a command to take a sample of the cooling water. The control unit 24 is a unit for controlling the sequence of shut-off valves 12 and 13, the sampling valve 16, the vent valve 17, and the auxiliary water valve 22, with the command signal S11 from the actuating device 23 as the trigger. While a computer can be used as the control unit 24, for example, an electrical circuit can also be used as the control unit 24. While a remote control unit can be used as the control unit 23, the control unit can, for example, be installed on a control panel together with the control unit 24.

[0032] It should be noted that in the present embodiment, the shut-off valves 12 and 13 are motorized on / off valves of the normally open type, whereas the sampling valve 16, the vent valve 17, and the auxiliary water valve 22 are motorized on / off valves of the normally closed type. For example, electromagnetically actuated on / off valves can be used as these valves, and the normally open type is a valve that is closed in a state where a solenoid is demagnetized, whereas the normally closed type is a valve that is open in a state where solenoids are demagnetized. The shut-off valves 12 and 13, the sampling valve 16, the vent valve 17, and the auxiliary water valve 22 are each actuated by instruction signals S1 to S5 from the control unit 24. Additionally, the vent line 15 is equipped with a water level indicator 25 (e.g.a level switch) and a detection signal S12 is entered from the water level indicator 25 into the control unit 24.

[0033] The further configurations of the sampling system 6' of the present embodiment are similar to those of the sampling system 6 of the first embodiment. -Valve control-

[0034] Fig. Figure 5 is a timing diagram illustrating the valve control procedure performed by the control unit. When the command signal S11 is input into the control unit 24 from the actuating device 23, the control unit 24 uses the command signal S11 as a trigger to output instruction signals S1 to S5 at appropriate times to the shut-off valves 12 and 13, the sampling valve 16, the venting valve 17, and the auxiliary water valve 22, thereby sequentially instructing the operations of the following steps S101 to S107. Step S101

[0035] Step S101 is a closing operation for the shut-off valves 12 and 13. In the case of cooling water sampling using the sampling system 6' of the present embodiment, a sampling bottle is first placed on the underside of an open end of the sampling line 14, a power source of the control unit 24 is switched on to actuate the actuator 23, and a sampling command is issued to the control unit 24. When the command signal S11 is received from the actuator 23, the control unit 24 issues instruction signals S1 and S2 to the shut-off valves 12 and 13, thereby instructing the shut-off valves 12 and 13 to close (time t1).This instruction causes a transition to a state in which the shut-off valves 12 and 13, the sampling valve 16, the venting valve 17 and the auxiliary water valve 22 are all closed and cooling water is sealed between the shut-off valves 12 and 13. Step S102

[0036] Step S102 is an opening operation of the sampling valve 16 and the vent valve 17. A set time is required from the issuance of an instruction to the shut-off valves 12 and 13 for the complete closing operation of the shut-off valves 12 and 13 to be completed. When the set time has elapsed from time t1 (time t2), the control unit 24 issues instruction signals S3 and S4 to the sampling valve 16 and the vent valve 17, thereby instructing the opening of the sampling valve 16 and the vent valve 17. This instruction causes a transition to a state in which the shut-off valves 12 and 13 and the auxiliary water valve 22 are closed, the sampling valve 16 and the vent valve 17 are open, and the cooling water, which is isolated between the shut-off valves 12 and 13, is discharged from the sampling line 14 to be recovered in the sampling bottle.

[0037] It should be noted that in a case where the opening of the sampling valve 16 and the vent valve 17 is instructed after the set time has been determined by the output of an instruction to the shut-off valves 12 and 13, another mode can be used to determine the time to instruct the opening of the sampling valve 16 and the vent valve 17. For example, a configuration can be used in which a limit switch is provided to detect a complete closure of the shut-off valves 12 and 13, and an opening instruction from the control unit 24 to the sampling valve 16 and the vent valve 17 is given when a signal of complete closure is received from the limit switch. Step S103

[0038] Step S103 is a closing operation of the sampling valve 16. A preset time is required from the opening of the sampling valve 16 and the vent valve 17 to complete the recovery of the cooling water. When this preset time has elapsed from time t2 (time t3), the control unit 24 stops sending the instruction signal S3 to the sampling valve 16, thereby instructing it to close. This instruction causes a transition to a state in which the shut-off valves 12 and 13, the sampling valve 16, and the auxiliary water valve 22 are closed, only the vent valve 17 is open, and in which a discharge from the bypass line 11 between the shut-off valves 12 and 13 can be initiated.

[0039] While one scenario has been described in which the closing of the sampling valve 16 after a set time is automatically instructed by the output of the instruction to the sampling valve 16 and the vent valve 17, another mode can be used to determine the timing for instructing the closing of the sampling valve 16. For example, an actuating device for issuing a command at the end of sampling is added, and when the actuating device is activated by a person performing sampling, an instruction to close can be given to the sampling valve 16 by the control unit 24 from the additional actuating device. The additional actuating device can be configured similarly to the actuating device 23. Step S104

[0040] Step S104 is an opening actuation of the auxiliary water valve 22. A set time is required from the cessation of the output of an instruction to the sampling valve 16 to complete the process of fully closing the sampling valve 16. When this set time has elapsed from time t3 (time t4), the control unit 24 outputs an instruction signal S5 to the auxiliary water valve 22, thereby instructing it to open. This instruction causes a transition to a state in which the shut-off valves 12 and 13 and the sampling valve 16 are closed, and the vent valve 17 and the auxiliary water valve 22 are open. As a result, water is fed into a pipeline between the shut-off valves 12 and 13 and the sampling valve 16, residual air in the pipeline is released from the vent line 15 and the water level in the vent line 15 is gradually raised.

[0041] It should be noted that, while one case has been described in which the opening of the auxiliary water valve 22 is instructed after a set time from the cessation of issuing a command to the sampling valve 16, another mode for determining the time to instruct the opening of the auxiliary water valve 22 can be used. For example, a configuration can be used in which a limit switch is provided to detect a complete closure of the sampling valve 16, and a command to open the auxiliary water valve 22 is issued by the control unit 24 when a signal indicating complete closure is received from the limit switch. Step S105

[0042] Step S105 is a closing operation of the auxiliary water valve 22. When the water level in the vent line 15 rises and the water level indicator 25 is switched on, the control unit 24 stops sending the instruction signal S5 to the auxiliary water valve 22 at a time delayed by time t from the time the water level indicator 25 is switched on, and instructs the auxiliary water valve 22 to close (time t5). This instruction causes a transition to a state in which the shut-off valves 12 and 13, the sampling valve 16, and the auxiliary water valve 22 are closed, and only the vent valve 17 is open. If the delay time t is ensured, the water level in the vent line 15 can rise to a higher position than the vent valve 17, even in the event of a fault. Step S106

[0043] Step S106 is the closing of the vent valve 17. A set time is required from the cessation of the output of an instruction to the auxiliary water valve 22 to complete the process of fully closing the auxiliary water valve 22. When the set time from time t5 has elapsed (time t6), the control unit 24 stops outputting the instruction signal S4 to the vent valve 17 and instructs the vent valve 17 to close. This instruction causes a transition to a state in which the shut-off valves 12 and 13, the sampling valve 16, the vent valve 17, and the auxiliary water valve 22 are all closed. Step S107

[0044] Step S107 is an opening operation of the shut-off valves 12 and 13. A set time is required from the cessation of the output of an instruction to the vent valve 17 to complete the operation of fully closing the vent valve 17. When this set time has elapsed (time t7), the control unit 24 stops outputting the instruction signals to the shut-off valves 12 and 13 and instructs them to open. This instruction causes a transition to a state in which the shut-off valves 12 and 13 are open, the sampling valve 16, the vent valve 17, and the auxiliary water valve 22 are closed, the state has been returned to the state before the start of sampling, and the valve control is complete.

[0045] It should be noted that, while one case has been described in which the opening of shut-off valves 12 and 13 is instructed after a set time from the cessation of an instruction to the vent valve 17, another mode for determining the time to instruct the opening of shut-off valves 12 and 13 can be used. For example, a configuration can be used in which a limit switch is provided to detect a complete closure of the vent valve 17, and an instruction to open shut-off valves 12 and 13 is given by the control unit 24 when the signal for complete closure is received from the limit switch. -Effects-

[0046] In the present embodiment, samples of cooling water can also be taken from the discharge line 8 under vacuum without using a large device such as a vacuum pump. The sampling system 6' can be easily applied to an existing system.

[0047] In addition, in the present embodiment, the sampling process of cooling water can be semi-automated using the control unit 24 and the operating sequence of the valves is not confused, which allows the sampling process to be carried out efficiently.

[0048] Furthermore, since the bypass line 11 is located at a lower position than the discharge line 8, when the shut-off valves 12 and 13 are opened after the sampling valve 16 and the vent valve 17 have been closed, air in the bypass line 11 can be discharged into the discharge line 8 after the cooling water has been sampled, similar to the first embodiment. This occurs due to the difference in specific density between the air and the cooling water. However, in the present embodiment, instead of such discharge using the difference in specific density between the air and the cooling water, the make-up water is supplied from the make-up water line 21 to the bypass line 11 after the cooling water has been sampled. Thus, by positively inducing discharge in the bypass line 11, a flow of cooling water can be re-established in the bypass line 11 after the cooling water has been sampled.

[0049] It should be noted that in the present embodiment, since the additional water is positively fed into the bypass line 11 to effect a discharge, the bypass line 11 does not necessarily have to be arranged at a lower position than the discharge line 8 and the bypass line 11 can be arranged at a higher position than the discharge line 8.

[0050] Additionally, since the water level indicator 25 is provided, which, as a trigger for issuing a closing instruction to the vent valve 17 after the cooling water sample has been taken, inputs a detection signal S12 into the control unit 24, the vent valve 17 is closed after the water level has actually risen to the vent valve 17. This also helps to limit the accumulation of air in the bypass line 11. It should be noted that, since the flow rate of supplementary water from the supplementary water line 21 is essentially constant and the time required for the water level in the vent line 15 to reach the vent valve 17 is essentially known, controlling the closing of the vent valve 17 by counting the time while this time is taken into account is also being considered.

[0051] Furthermore, while an example has been described in the present embodiment in which valve control is carried out by the control unit 24 with the sampling system 6', which has the auxiliary water line 21 and the auxiliary water valve 22, as its target, a configuration can also be used in which the valves in the first embodiment are designed to be of the motor-driven type, and the opening and closing of the valves is controlled by the control unit 24.

[0052] Additionally, while an example has been described in which the sampling system 6', which is subject to valve control by the control unit 24, is provided with the auxiliary water line 21 and the auxiliary water valve 22, the auxiliary water line 21 and the auxiliary water valve 22 can also be applied to the sampling system 6 in the first embodiment. In this case, the auxiliary water valve 22 can be a manually operated on / off valve similar to the shut-off valves 12 and 13.

[0053] While in the present embodiment an example has been described in which normally open or normally closed type valves are used as the shut-off valves 12 and 13 and the sampling valve 16 and the like, valves of the type in which both an opening operation and a closing operation are performed by actuators can be used as the shut-off valves 12 and 13 and the sampling valve 16 and the like. Third embodiment

[0054] Fig.Figure 6 is a schematic diagram illustrating the configuration of an inlet of a bypass line in a sampling system according to a third embodiment of the present invention and its surroundings. The present embodiment differs from the first embodiment in that the inlet 11a of the bypass line 11 projects into the interior of the discharge line 8 and opens towards the upstream side of the discharge line 8. In the present embodiment, an upper end of the lowering section 11c of the bypass line 11 is bent in an L-shape, and the inlet 11a faces the flow of cooling water through the discharge line 8.

[0055] The other configurations are similar to those of the first embodiment or the second embodiment.

[0056] According to the present embodiment, in addition to effects similar to those of the first embodiment or the second embodiment, due to the structure in which the inlet 11a of the bypass line 11 faces the flow of cooling water flowing through the discharge line 8, the cooling water can be efficiently introduced into the bypass line 11 using a dynamic pressure of the cooling water. Description of reference symbols 4 Capacitor 6, 6' Sampling system 8 Delivery line 11 Bypass line 11a Entrance (branch section) 11b Outlet (connecting part) 12, 13 Shut-off valve 14 Sample collection line 15 Vent line 16 Sampling valve 17 Vent valve 21 Additional water line 22 Auxiliary water valve 23 Actuating device 24 control unit S11 command signal

Claims

[1] Sampling system (6; 6') for sampling cooling water flowing through a discharge line (8) extending from a condenser (4) to a sea, wherein the sampling system (6; 6') is characterized by: a bypass line (11) which branches off from the discharge line (8) and connects to the discharge line (8); two shut-off valves (12, 13) in the bypass line (11); a sampling line (14) which branches off from the bypass line (11) between the two shut-off valves (12, 13); a vent line (15) which branches off from the bypass line (11) between the two shut-off valves (12, 13); a sampling valve (16) in the sampling line (14); and a vent valve (17) in the vent line (15); an additional water line (21) which is connected to the bypass line (11); an additional water valve (22) in the additional water line (21); an actuating device (23) which issues a command signal (S11) for a command to take a sample of the cooling water; and a control unit (24) which controls the two shut-off valves (12, 13), the vent valve (17), the sampling valve (16) and the auxiliary water valve (22) with the command signal (S11) from the actuating device (23) as trigger, wherein the two shut-off valves (12, 13) are motorized on / off valves of the normally open type, whereas the vent valve (17), the sampling valve (16) and the auxiliary water valve (22) are motorized on / off valves of the normally closed type, and The control unit (24) then, when the command signal (S11) is entered by the actuating device (23), sequentially instructs as follows: Closing the two shut-off valves (12, 13), Opening the sampling valve (16) and the venting valve (17), Closing the sampling valve (16), Opening the auxiliary water valve (22), Closing the auxiliary water valve (22), Closing the vent valve (17) and Opening the two shut-off valves (12, 13). [2] Sampling system (6; 6') according to claim 1, wherein the bypass line (11) is arranged at a higher position than a flood level. [3] Sampling system (6; 6') according to claim 1, wherein the sampling system (6; 6') is arranged at a lower position in relation to the delivery line (8). [4] Sampling system (6; 6') according to claim 1, wherein an inlet (11a) of the bypass line (11) projects into an interior of the delivery line (8) and opens to an upstream side of the delivery line (8). [5] Sampling procedure for cooling water using a sampling system (6, 6') comprising: a bypass line (11) which branches off from the discharge line (8) and connects to the discharge line (8); two shut-off valves (12, 13) in the bypass line (11); a sampling line (14) which branches off from the bypass line (11) between the two shut-off valves (12, 13); a vent line (15) which branches off from the bypass line (11) between the two shut-off valves (12, 13); a sampling valve (16) in the sampling line (14); and a vent valve (17) in the vent line (15), the procedure includes the following: Opening the two shut-off valves (12, 13), closing the sampling valve (16) and the vent valve (17) and allowing the cooling water to flow into the bypass line (11), Closing the two shut-off valves (12, 13), opening the sampling valve (16) and the vent valve (17) and taking a sample of the cooling water that is enclosed between the two shut-off valves (12, 13) from the sampling line (14) and then closing the sampling valve (16) and the venting valve (17), opening the two shut-off valves (12, 13) and reintroducing the cooling water into the bypass line (11).

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