JP2009024935A - Flow rate control system of circulating pump and flow rate control method of circulating pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for controlling a circulating pump so that a temperature difference between an intake and a water discharge port does not exceed a pollution prevention agreement value in a cooling system utilizing seawater as cooling water. <P>SOLUTION: In this system 20 for controlling a discharge flow rate of the circulating pump 11, seawater is taken in from the intake 12 by the circulating pump 11, the taken seawater is utilized as cooling water, and the seawater already utilized as the cooling water is discharged to the sea from the water discharge port 14. The system 20 includes: a sea level measuring part 22 for measuring a sea level in the vicinity of the intake 12; and a flow rate control part 21 for increasing the discharge flow rate of the circulating pump 11 when the measured sea level is not higher than a preset lower limit sea level. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flow rate control system and a flow rate control method for a circulating pump of cooling water in a cooling system using seawater as cooling water in a power plant or the like.

  Conventionally, in a power plant, for example, as described in Patent Document 1, seawater is taken from a water intake by a condenser cooling system and used as cooling water in the condenser, and then the seawater is discharged from a water outlet. The condenser is cooled by discharging it to The difference in water temperature between the intake port and the discharge port in such facilities is determined to be less than a predetermined agreement value (7 ° C.) by a pollution prevention agreement in order to prevent an increase in seawater temperature.

For this reason, conventionally, a thermometer is installed near the intake and outlet, and the water temperature at the intake and outlet is monitored, and an alarm is issued if the difference in water temperature between the intake and outlet exceeds the set value. When the operator increases the discharge flow rate of the circulation pump, the temperature of seawater discharged from the water discharge port is lowered to reduce the temperature difference.
Japanese Patent Laid-Open No. 2002-340483

  However, when the flow rate of the pump is adjusted manually by the operator as described above, it becomes a response after an alarm is issued, and there is a possibility that the pollution prevention agreement value cannot be observed. In addition, the operator is burdened by manual work by the operator.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to prevent a temperature difference between the intake port and the discharge port from exceeding a predetermined allowable value in a cooling system using seawater as cooling water. It is to provide a system for controlling the circulation pump.

  The flow control system of the circulation pump of the present invention is a cooling system that takes in seawater from a water inlet by a circulation pump, uses the taken seawater as cooling water, and discharges the seawater after being used as cooling water from the outlet to the sea. A system for controlling the discharge flow rate of the circulation pump, wherein a tide level measuring means for measuring a tide level near the intake port, and when the measured tide level is less than or equal to a preset lower limit tide level, And a flow rate control means for increasing the discharge flow rate.

  In the above flow rate control system, the flow rate control means may increase the discharge flow rate of the circulation pump when the measured tide level is equal to or higher than a preset upper limit tide level.

  Moreover, the control method of the circulation pump of the present invention is a cooling system that takes in seawater from a water inlet by a circulation pump, uses the taken seawater as cooling water, and discharges the seawater after being used as cooling water from the outlet to the sea In which the tide level near the intake is measured, and when the measured tide level is below a preset lower tide level, the discharge flow rate of the circulation pump is It is characterized by increasing.

  According to the present invention, since the flow rate can be increased before the temperature of the seawater discharged from the water discharge port excessively increases, the temperature difference between the water intake port and the water discharge port is surely equal to or less than a predetermined allowable value. It can be. Further, since the discharge flow rate of the circulation pump can be adjusted by the control of the system, it is possible to reduce the labor of the operator.

Hereinafter, an embodiment of a flow control system for a circulation pump of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a condenser cooling system 10 to be controlled by a flow rate control system for a circulation pump according to the present embodiment. As shown in the figure, the condenser cooling system 10 takes in seawater from a water intake 12 provided in the sea by a circulation pump 11 and uses it as cooling water in the condenser 13, and then releases the water provided in the sea. It is a system that discharges water from the water inlet 14 to the sea.

  As the circulation pump 11, for example, a pump capable of adjusting the discharge flow rate such as a vertical axis movable blade circulation pump can be used. The vertical axis movable blade circulation pump is a pump having a rotating blade attached to a rotating shaft and sucking up and discharging seawater as the moving blade rotates. By increasing the opening of the moving blade, the discharge flow rate can be increased.

  As described in the column of the prior art, conventionally, a thermometer is installed in the vicinity of the water intake 12 and the water outlet 14, and an alarm is issued when the difference in water temperature between the water intake 12 and the water outlet 14 reaches a set value. It was. However, since the alarm is issued after the difference in water temperature reaches the set value, even if the discharge flow rate of the circulation pump 11 is increased after the alarm, the difference in water temperature between the water intake 12 and the water outlet 14 may be 7 ° C. or more. there were.

  Therefore, the inventors investigated the relationship between the tide level at the water intake 12 and the time at which the alarm is issued in order to identify the cause of the difference in water temperature between the water intake 12 and the water discharge port 14. FIG. 2 is a graph showing the relationship between the tide level of the water intake 12 and the time at which an alarm is issued. As shown in the figure, it can be seen that an alarm is issued when the tide level rises due to high tide and when the tide level drops due to low tide.

  For this reason, the inventors consider that the tide level of seawater is one of the causes of the increase in the temperature difference between the intake port 12 and the discharge port 14, and experimentally investigated the relationship between the discharge pressure of the circulation pump 11 and the tide level. It was. FIG. 3 is a graph showing the relationship between the tide level and the discharge pressure of the circulation pump 11. As shown in the figure, it can be seen that when the tide level is lowered due to low tide, the discharge pressure of the circulation pump 11 is lowered.

  Such a phenomenon is considered to occur for the following reason. That is, when the tide level is lowered due to low tide, the water pressure at the suction port of the circulation pump 11 is lowered, so that the suction flow rate of the circulation pump 11 is lowered and the discharge pressure of the circulation pump 11 is lowered. When the discharge pressure of the circulation pump 11 decreases, the flow rate of seawater passing through the condenser 13 decreases. For this reason, the time for performing heat exchange between seawater and steam in the condenser 13 becomes excessively long, and the temperature of the seawater discharged from the water outlet 14 increases. For this reason, it is considered that when the tide level decreases, the temperature of the seawater discharged from the water outlet 14 increases.

The inventors configured the flow control system 20 of the present embodiment to be described below based on the above examination results.
FIG. 4 is a diagram illustrating the flow rate control system 20 of the circulation pump 11 according to the present embodiment. As shown in the figure, the flow rate control system 20 is electrically connected to the circulation pump 11, and is electrically connected to the flow rate control unit 21 that controls the discharge flow rate of the circulation pump 11 and the flow rate control unit 21. And a tide level measurement unit 22 that measures the tide level of the surface.

The tide level measurement unit 22 transmits the tide level measurement result to the flow rate control unit 21.
The flow rate control unit 21 stores in advance in the storage unit the upper and lower tide levels obtained based on the relationship between the discharge pressure of the circulation pump 11 and the tide level obtained by the above experiment, and the tide level measurement unit When the tide level measured by 22 exceeds the upper tide level and when the measured tide level is lower than the lower tide level, the discharge flow rate of the circulation pump 11 is increased.

  As shown in FIG. 5, the upper tide level is lower than the tide level at the time when the alarm was issued near the high tide time in the relationship between the change in the tide level obtained from the above experiment and the time when the alarm was issued. Set as follows. Similarly, the lower tide level is set to be higher than the tide level when an alarm is issued near the low tide time. Thus, the upper tide level and the lower tide level may be set based on the measured tide level by measuring the tide level such that the temperature difference exceeds the allowable value near the time of high tide and low tide.

  According to the above configuration of the circulation pump flow control system 20 of the present embodiment, when the seawater tide level is lowered by low tide, and the seawater tide level measured by the tide level measurement unit 22 falls below the lower limit tide level, the discharge of the circulation pump 11 Increase the flow rate. As a result, a decrease in the flow rate of the seawater in the condenser 13 due to a decrease in the tide level of the seawater is compensated, and a decrease in the flow velocity of the seawater passing through the condenser 13 can be prevented. For this reason, the time for performing heat exchange between seawater and steam in the condenser 13 does not become excessively long, and an increase in the temperature of the seawater discharged from the water outlet 14 can be suppressed.

  Moreover, when the tide level rises due to high tide and exceeds the upper limit tide level, the discharge flow rate of the circulation pump 11 increases. Thereby, since the quantity of the seawater which passes the inside of the condenser 13 increases, the raise of the temperature of the seawater discharged | emitted from the water discharge port 14 can be suppressed.

  As described above, according to the circulation pump flow control system 20 of the present embodiment, when the tide level becomes lower than the lower limit tide level, the discharge flow rate of the circulation pump 11 is increased, so the temperature of the seawater discharged from the water outlet 14 is increased. The temperature rise can be suppressed before the temperature rises excessively. Similarly, when the tide level exceeds the upper limit tide level, the discharge flow rate of the circulation pump 11 is increased, so that the temperature rises before the temperature of the seawater discharged from the water outlet 14 rises excessively. Can be suppressed. As a result, according to this embodiment, the temperature difference between the water intake port 12 and the water discharge port 14 can be reliably made less than the pollution prevention agreement value. Further, since the discharge flow rate of the circulation pump 11 can be adjusted by the flow rate control system 20, it is possible to reduce the time and effort of the operator's operation.

  In addition, although this embodiment demonstrated the case where it controlled so that the temperature difference of the water intake 12 and the water discharge port 14 became less than 7 degreeC which is a pollution prevention agreement value, it does not restrict to this but sets to the flow control part 21 The temperature difference between the water intake 12 and the water outlet 14 can be adjusted by appropriately setting the upper and lower tide levels.

In the present embodiment, the case where the vertical axis movable blade circulation pump is used as the circulation pump 11 has been described. However, the present invention is not limited thereto, and any pump that can adjust the discharge flow rate can be used as the circulation pump 11. .
Moreover, although this embodiment demonstrated the case where the condenser 13 of a power plant was cooled, it can apply widely, when not only this but using seawater as cooling water.

It is a figure which shows the structure of the cooling system by the condenser used as the control object by the flow control system of the circulation pump of this embodiment. It is a graph which shows the relationship between the tide level of a water intake, and the time which issues a warning. It is a graph which shows the relationship between a tide level and the discharge pressure of a circulation pump. It is a figure which shows the flow control system of the circulation pump of this embodiment. It is a figure for demonstrating the setting method of an upper limit tide level and a lower limit tide level.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cooling system 11 Circulation pump 12 Intake port 13 Condenser 14 Outlet 20 Flow rate control system 21 Flow rate control unit 22 Water level measurement unit

Claims (3)

It is a system that controls the discharge flow rate of the circulation pump in a cooling system that takes in seawater from the water outlet with a circulation pump, uses the taken seawater as cooling water, and discharges the seawater after being used as cooling water to the sea from the outlet. There,
Tide level measuring means for measuring the tide level in the vicinity of the intake;
A flow rate control system for a circulating pump of cooling water, comprising: a flow rate control means for increasing the discharge flow rate of the circulation pump when the measured tide level is equal to or lower than a preset lower limit tide level. A flow control system for a circulating pump according to claim 1,
The flow rate control means is
When the measured tide level is equal to or higher than a preset upper limit tide level, the discharge flow rate of the circulation pump is increased. A method for controlling the discharge flow rate of the circulation pump in a cooling system that takes in seawater from a water outlet with a circulation pump, uses the taken seawater as cooling water, and discharges the seawater after being used as cooling water to the sea from the outlet. There,
Measure the tide level near the intake,
When the measured tide level is equal to or lower than a preset lower limit tide level, the cooling water circulation pump flow rate control method is characterized in that the discharge flow rate of the circulation pump is increased.

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