JPH07200069A - Cooling water control device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a cooling water control device capable of energy saving operation by suppressing an increase in the amount of cooling water even when the cooling water temperature exceeds a specified value. is there. According to the present invention, there is provided a cooling water control device for cooling heat generated from a thermal power plant, a fan for general industry, a cooler, bearings or the like with cooling water, wherein a temperature control valve is provided at an inlet and an outlet of the cooler. A cooling water flow rate detector is provided, and when the amount of cooling water detected by the cooling water flow rate detector is above the specified level, the opening of the temperature control valve is locked at the specified value, and the automatic refueling temperature constant control automatically starts. When the lubrication temperature change operation is started and the oil supply temperature alarm set point is exceeded, the set temperature is changed to increase the amount of cooling water and the oil supply temperature constant control operation is performed again, and when the cooling water temperature rises further Since a control device for maintaining the cooler outlet temperature at the set temperature by operating in parallel with the spare cooler is provided,
Even if the cooling water temperature exceeds the specified value, the energy saving operation can be performed by reducing the increase of the cooling water amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling water controller for cooling components of thermal power plants and general industrial equipment.

[0002]

2. Description of the Related Art Conventionally, in many plants, a cooling water system has been employed in which heat is taken out from plant equipment by utilizing cooling water, the heat is dissipated in a cooling tower, and is circulated again as cooling water.

For example, focusing on a thermal power plant,
Equipment to be cooled includes fans, oil coolers for steam turbines, hydrogen coolers for generators, vacuum pumps, boiler feed pumps, control compressors, coal mills, and the like. Among these, the equipment that requires a large amount of cooling water is the oil cooler of the steam turbine and the hydrogen cooler of the generator. Although there are differences depending on the capacity of the plant, etc., each is about 30% or more of the total cooling water quantity. Are using.

Further, the design of the cooling equipment is such that the change in atmospheric temperature and humidity during the season or day and night, the cooling water temperature determined by the characteristics of the cooling tower, and the medium temperature determined by the operating characteristics of the medium to be cooled. Is taken into consideration. By the way, the temperature of the oil required to lubricate the bearings of a steam turbine is generally 4
The temperature control of the lubricating oil by the cooling water is 3 to 49 ° C.
This is done by manually controlling the amount of cooling water as appropriate.

On the other hand, in large plants, in order to save labor, a temperature control valve is provided at the inlet or the outlet of the equipment so that the temperature of the cooling medium is controlled to a certain temperature, and the amount of cooling water is changed in response to changes in the cooling water temperature. Is controlled to keep the temperature of the cooling medium constant.

FIG. 2 is a block diagram of a typical cooling water system, showing a system system configuration in which a temperature control valve is provided at the inlet of the oil cooler. That is, in the figure, the cooling water supplied through the water supply line 2 via the cooling water pump 1A is branched, one is supplied to the oil cooler 4A via the temperature control valve 3 and the cooling water inlet valve 8A, and the other is supplied to the temperature It is supplied to the cooler 14 in which the control valve 3 is not installed. In the oil cooler 4A, the cooling water whose temperature has risen due to the heat exchange between the oil and the cooling water is returned to the cooling tower 16 via the cooling water outlet valve 9A and the drain line 15, where the heat is dissipated there and the pump 1A is again used as the cooling water. Is supplied to. Lubricating oil is supplied from the lubricating oil inlet valve 10A to the oil cooler 4A and circulated through the lubricating oil outlet valve 11A and the circulating oil line 17. Reference numeral 7 is a control device. Further, as a spare oil cooler 4B, cooling water inlet valve 8B, cooling water outlet valve 9B, lubricating oil inlet valve 10B, lubricating oil outlet valve 11
B and a line therefor are provided as shown.

By the way, the control device 7 operates as follows. That is, if the cooling water temperature is below the specified value,
The amount of cooling water is reduced by controlling the opening of the temperature control valve 3 by the signal 18 of the oil supply temperature detector 5 so that the oil supply temperature becomes the set value, but when the temperature of the cooling water rises, the amount of cooling water is increased. Then, when the amount of cooling water exceeds a specified value, the opening of the temperature control valve 3 is controlled so as to be restricted to the specified flow rate. This cooling water system can greatly reduce the cooling water amount when the cooling water temperature is low, so that the effect of reducing the entire cooling water amount is achieved.
As a result, it can contribute to the reduction of pump power and is often installed in equipment that uses a large amount of cooling water.

Here, the above-mentioned cooling water outlet temperature of the cooling tower is the summer average daily maximum temperature of the place where the plant is installed, and the cooling water amount of each device and the planned heat exchange amount (cooling water amount) based on the average temperature. And the cooling water temperature rise)), so when the summer average daily maximum temperature and the amount of heat exchanged for each device are larger than planned, or when the cooling tower itself has decreased in performance or has not reached its performance. Means that the cooling water supply condition to each device does not satisfy the specified value.

As an example, consider the case where the temperature of the cooling water coming out of the cooling tower does not satisfy the specified value, such as during the daytime in summer. FIG. 3 is a characteristic curve showing the relationship between the equipment cooling water inlet temperature and the oil outlet temperature (oil supply temperature to the steam turbine) when the amount of cooling water is used as a parameter in the oil cooler of the steam turbine. For example, the cooling water inlet temperature is 33 ° C and the oil outlet temperature is 4
If the cooling water amount is designed to be 100% at 6 ° C and the cooling water temperature in summer rises to 35 ° C for the above-mentioned reason, the temperature control valve at the oil cooler inlet causes the oil outlet temperature to reach the specified value of 46 ° C. The opening is increased to maintain the temperature at 0 ° C. and the cooling water is opened until it reaches 230%. This means that if the system in which the oil cooler is designed to be 30% of the total cooling water amount, if the cooling water amount increases to 35 ° C, the total cooling water amount will be 13
This means that the amount of cooling water is required to be 9%, and the required amount of cooling water cannot be supplied by the normal operation of one pump, so that it is necessary to operate the two pumps by charging the standby machine.

[0010]

In a device provided with a temperature control valve, such as the oil cooler described above, when the temperature of the cooling water is lower than the specified temperature, the amount of the cooling water is reduced, which saves labor and energy. However, once the specified cooling water temperature is exceeded, 100 ° C → 150% at 1 ° C and 100 → 230% at 2 ° C.
It has a characteristic that the amount of cooling water must be rapidly increased to 100%, and it was necessary to always pay attention to the necessity of operating two pumps with a standby machine, such as during the daytime in summer.

The present invention has been made in view of the above circumstances, and an object thereof is to enable an energy-saving operation by suppressing an increase in the amount of cooling water even when the temperature of the cooling water exceeds a specified value, and further to perform cooling. The cleanliness of the vessel is constantly monitored, and if the cleanliness deteriorates, appropriate switching timing is planned,
It is an object to provide a cooling water control device that can be switched to a spare cooler.

[0012]

In order to achieve the above object, the first aspect of the present invention is that heat generated from equipment such as a thermal power plant, a fan for general industry, bearings, etc. is supplied by a pump. In the cooling water control device configured to exchange heat between the cooling water and the cooling device, dissipate the heat of the heated water in the cooling tower, and circulate the cooling water again as cooling water in the cooling device. Also, a temperature control valve and a cooling water flow rate detector are installed at the outlet, and when the amount of cooling water detected by the cooling water flow rate detector is above the specified value, the opening of the temperature control valve is locked at the specified value to refuel. When the temperature change control automatically shifts to the refueling temperature change operation, and if the refueling temperature alarm set point is exceeded, the set temperature is changed to increase the cooling water amount and the refueling temperature constant control operation is performed again. Cooling water temperature When the temperature, characterized in that a control device for maintaining the cooler exit temperature by parallel operation with pre-cooler at the set temperature.

According to a second aspect of the present invention, in the cooling water control device according to the first aspect, a cooling water temperature detector is provided on the cooling device inlet side, and a detection signal of the cooling water temperature detector is used to clean the cooling device. A diagnostic device for diagnosing based on a characteristic diagram showing the degree is provided.

[0014]

According to the cooling water control device of the present invention, when a flow rate detector is additionally installed in the conventional system having a temperature control valve and the control device calculates, when the cooling water amount exceeds the specified condition,
Depending on the detected amount of cooling water, the opening of the temperature control valve can be locked at the specified value to automatically change from the constant refueling temperature control operation to the refueling temperature change operation. For example, the set temperature (set temperature from 46 to 49 ° C.) can be changed to increase the amount of cooling water, and the oil supply temperature constant control operation can be performed again to reduce the chance of operating two pumps. Even if the cooling water temperature rises further, the oil outlet temperature can be maintained at the set temperature by operating the oil cooler in parallel with the standby machine, and the flow velocity inside the tube of the oil cooler can be kept within the limit. it can. Furthermore, by constantly monitoring the cleanliness, it is possible to switch to the standby machine at an appropriate timing.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a system configuration diagram of an embodiment of the present invention.
The same components as those in FIG. 2 already described will be denoted by the same reference numerals in the following description. In the figure, the cooling water supplied by the cooling water pump 1A via the water supply line 2 is branched, one is supplied to the oil cooler 4A via the temperature control valve 3 and the cooling water inlet valve 8A, and the other is temperature control valve. 3 is supplied to the cooler 14 not installed. In the oil cooler 4A, the cooling water whose temperature has risen due to heat exchange between the oil and the cooling water is cooled by the cooling water outlet valve 9A,
It is returned to the cooling tower 16 via the drain line 15, where heat is dissipated, and is returned to the pump 1A as cooling water again.

A flow rate detector 6 is mounted on the drain line 15 connected to the oil cooler 4A, and an electric signal 18 of the flow rate detector 6 and the oil supply temperature detection installed in the lubricating oil line 17 are detected. The electric signal 18 ′ of the container 5 is input to the control device 7 and calculated to generate an opening signal of the temperature control valve 3.

If the cooling water temperature is below the specified value, the signal 18 'of the oil supply temperature detector 5 is set so that the oil supply temperature becomes the set value.
The cooling water amount is throttled by controlling the opening degree of the temperature control valve 3 by the, but when the cooling water temperature rises, the cooling water amount increases, and when the cooling water amount exceeds the specified value, the signal of the flow rate detector 6 Is prioritized, and the control device 7 calculates so as to limit the opening degree of the temperature control valve 3 to the specified flow rate.

If the temperature of the cooling water further rises, regardless of the signal 18 'of the oil supply temperature detector 5, the operation for increasing the oil supply temperature within the specified upper limit is performed. When the oil supply temperature exceeds the upper limit, the set value of the oil supply temperature is reset to the upper limit of the oil supply temperature, the signal of the flow rate detector 6 is overcome, and the amount of cooling water is increased again.

As described above, the control by the control unit 7 can reduce the increase in the amount of cooling water with respect to the increase in the temperature of the cooling water as compared with the conventional case, and can reduce the chance of operating the two pumps 1A and 1B.

Furthermore, when the temperature of the cooling water rises and the temperature control valve 3 is fully opened and the oil supply temperature cannot be maintained at the set value, the cooling water inlet valve 8B, the cooling water outlet valve 9B and the cooling water outlet valve 9B of the spare oil cooler 4B and Lubricating oil inlet valve 10B, lubricating oil outlet valve 11
B is opened and two oil coolers 4A and 4B are operated in parallel, and the temperature control valve 3 and the bypass valve 25 are opened to secure the required amount of cooling water and maintain the oil supply temperature at the set value.

The functions of the control device 7 of this embodiment will be described below with reference to FIG.
This will be described with reference to the functional flow diagram of FIG. 6 and the characteristic diagram showing the mutual level relationship of each signal in FIG. 5 and 6, the signal PV of the oil supply temperature detector 5 and the setting device 19A or 1
The setting signal SV of 9B is selected by the changeover switch 20A, compared, PID adjusted by the controller 21, and MV-1.
Signal to the low-value priority circuit (hereinafter referred to as LVG) 23.

On the other hand, as for the signal of the flow rate detector 6, the opening transmitter 22 selects the signal shown in the input-output relationship diagram and the signal via the setter 19C, the changeover switch 20C and the rate limiter 24 with the changeover switch 20B. And LV with the signal of MV-2
Input to G23. Both signals MV-1 and MV-2 are compared here, and the low value signal is prioritized and becomes the input signal of the control valve 3 as the MV signal. When the MV signal upper limit or the amount of cooling water is equal to or higher than the oil cooler tube flow velocity limit value, the cooling water inlet / outlet valve 8B. 9B, lubricating oil inlet / outlet valve 10
An opening command is output to B, 11B and the temperature control valve bypass valve 25.

Here, the relationship between the cooling water temperature and the cooling water amount is expressed in several control ranges, for example, control range (1) as follows.
The description will be divided into (5). [Control range (1)] When the cooling water temperature rises under a certain settling condition, the oil outlet temperature rises due to the characteristics shown in FIG.
Normally, the oil temperature is set to 46 ° C. by the setter 19A, so the deviation signal is calculated by the controller 21 and increased by the MV-1 signal.

On the other hand, when the flow rate of the flow rate detector 6 is less than the specified value, the signal of the opening transmitter 22 is at the 100% position, and the changeover switch 20B transmits this value to the LVG 23 as the MV-2 signal. . Both signals are compared by the LVG 23, and the low value MV-1 signal is prioritized, and the opening signal of the control valve 3 is generated as the MV signal.

[Control range (2)] When the cooling water temperature further rises, the cooling water amount increases, and when the cooling water amount exceeds the specified value, the signal of the flow rate detector 6 is sent by the opening transmitter. Create an output signal MV-2 that maintains the specified flow rate. Further, the VP signal of the oil supply temperature detector 5 rises due to the flow rate limitation, and the signal S
V is compared, the deviation signal is calculated by the controller 21, and MV is calculated.
-1 signal. Both signals are compared by the LVG 23, and the low-value MV-2 signal is prioritized and the opening of the control valve 3 is maintained at the specified flow rate as the MV signal, so the oil outlet temperature continues to rise.

[Control range (3)] When the temperature further rises from the above state, the amount of cooling water is kept constant and the oil outlet temperature continues to rise to 49 ° C.

[Control range (4)] When the temperature of the cooling water is such that the oil outlet temperature exceeds 49 ° C, the temperature setting device is set to 19B from 19A and set to 49 ° C by the changeover switch 20A. , PV signal is compared with the deviation signal, and the deviation signal is calculated by the controller 21 to become the MV-1 signal. On the other hand, the signal of MV-2 is switched from the opening transmitter 22 to the setter 19C by the changeover switches 20B and 20C, and increases at the rate of change of the rate limiter 24. Both signals are compared by the LVG 23, and the low value MV-1 is prioritized, the cooling water amount restriction is released, and the cooling water amount control with the set value of 49 ° C. is transferred again.

[Control range (5)] Further, if the temperature of the cooling water rises and the MV signal reaches the upper limit or the amount of cooling water exceeds the tube flow rate limit of the oil cooler 4, the cooling water inlet / outlet valves 9B, 8B. The opening command is output to the lubricating oil inlet / outlet valves 11B and 10B, and the two oil coolers 4 are operated in parallel. An open signal is also output to the temperature control valve bypass valve 25,
The required cooling water amount is secured, and the cooling water amount control with the set value set at 49 ° C. is continued.

Further, the signal of the cooling water temperature detector 12, the signal of the flow rate detector 6 and the signal of the oil supply temperature detector 5 are input to the diagnostic device 13, and the diagnostic device 13 calculates from the curve shown in FIG. Degree is required. When the cleanliness deteriorates and it becomes necessary to clean the oil cooler 4, guidance is given by an alarm to that effect.

In the control by the control device 7 described above, the description of the first half of the control range (1) to the control range (5) is a measure associated with the rise in the cooling water inlet temperature, and the second half of the control range (5) is the cooling. This is a measure against deterioration of the container itself. That is, in the former case, when the cooling water temperature exceeds the specified value, the flow rate to the oil cooler is constantly monitored, and if the cooling water amount exceeds the specified value, the opening of the temperature control valve Is fixed in that state, and if the cooling water temperature rises further, it tries to operate by changing the oil outlet temperature of the oil cooler at a specified flow rate. For example, the cooling water temperature rises to 35 ° C. In this case, the oil outlet temperature becomes 48 ° C., and the oil temperature is changed within the operation limit on the oil side for operation.

Further, an alarm point is set for the upper limit of the normal oil outlet temperature, and if the alarm point is exceeded, the set temperature is again set to the upper limit (49
℃), the amount of cooling water can be reduced by starting the control of the cooling water control valve, and the chance of operating two cooling water pumps can be reduced. In addition, if the cooling water temperature rises and the cooling water control valve is fully opened and the oil outlet temperature cannot be maintained at the set temperature, or if the cooling water amount increases and the tube flow rate of the oil cooler is restricted, the spare side The oil cooler can be used to operate two oil coolers in parallel, and by opening the bypass valve of the cooling water control valve to secure the amount of cooling water, the oil outlet temperature can be maintained at the set temperature, and the amount of cooling water can be reduced. Can be achieved.

In the latter case, unlike the former case, the problem relating to the deterioration of the cooler itself is solved. According to the relation curve showing the relation between the equipment cooling water inlet temperature and the oil outlet temperature by the parameter of the cleanliness when the amount of cooling water is constant in the oil cooler shown in FIG. 4, the same design system as in the case of FIG. 3 is obtained. In case,
It is shown that even if the cooling water temperature is the same, if the cleanliness deteriorates, there is a characteristic relation that the oil outlet temperature rises in the same way as the cooling water temperature rises.

In general, the heat exchange amount of the equipment hardly changes with time and is constant irrespective of the load of the steam turbine. Therefore, the fact that the oil outlet temperature rises at the same cooling water temperature means that the oil cooler is opposite. It can be inferred that the cleanliness of No. 1 has deteriorated. For example, if the cooling water temperature is 34 ° C, the cleanliness is 1
Since the oil outlet temperature at 00% is 47 ° C, the oil outlet temperature is 4
It means that the oil cooler has a cleanliness of 95.
It has fallen to%. In this way, monitor changes in cleanliness from the amount of cooling water, cooling water temperature, and oil outlet temperature, and when cleanliness deteriorates, use an alarm or other guidance to switch the oil cooler to a standby machine and clean the regular machine. Can judge the timing of switching / cleaning. It should be noted that it is possible to automatically switch to the standby machine and also to display the cleanliness level.

[0034]

As described above, according to the present invention, even if the cooling water temperature exceeds the specified value, the increase in the cooling water amount can be controlled to be smaller than in the conventional case, and the opportunity of operating two cooling water pumps can be provided. The energy consumption can be reduced because it can be reduced, and the reliability of the system can be improved by securing a spare pump. further,
When the temperature of the cooling water rises, the cooler including the spare unit 2
It is also possible to lower the design temperature of the cooler and cooling tower by operating the unit. In addition, by constantly monitoring the cleanliness of the cooler and providing guidance when the cleanliness deteriorates, proper switching timing is achieved, the operation of the cooler is expanded, and the flexibility of the plant is increased. Produce an effect. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of a cooling water system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional cooling water system.

FIG. 3 is a characteristic diagram showing the relationship between the cooling water temperature and the oil supply temperature with respect to the cooling water amount.

FIG. 4 is a characteristic diagram showing a relationship between cooling water temperature and oil supply temperature with respect to cleanliness.

FIG. 5 is a functional flowchart of the control device according to the present invention.

FIG. 6 is a diagram showing a mutual level relationship of each signal according to the present invention.

[Explanation of symbols]

1 ... Cooling water pump, 2A, 2B ... Water supply line, 3 ... Temperature control valve, 4A, 4B ... Oil cooler, 5 ... Oil supply temperature detector,
6 ... Flow rate detector, 7 ... Control device, 8A, 8B ... Cooling water inlet valve, 9A, 9B ... Cooling water outlet valve, 10A, 10B ... Lubricating oil inlet valve, 11A, 11B ... Lubricating oil outlet valve, 12 ... Cooling Water temperature detector, 13 ... Diagnostic device, 14 ... Cooler, 15
… Drain line, 16… Cooling tower, 17… Lubricant line,
18, 18 '... Electric signal, 19A, 19B, 19C ... Setting device, 20A, 20B, 20C ... Changeover switch, 21 ...
Controller, 22 ... Opening degree transmitter, 23 ... Low value priority circuit, 24
… Late limiter, 25… Temperature control valve bypass

Claims (2)

[Claims] 1. The heat generated from equipment such as a thermal power plant, a fan for general industry, bearings and the like is exchanged with cooling water supplied by a pump and a cooler, and the heated water is supplied to a cooling tower. In a cooling water control device configured to dissipate heat and circulate again as cold water in the pump,
A temperature control valve and a cooling water flow rate detector are provided at the inlet and outlet of the cooler, and when the amount of cooling water detected by the cooling water flow rate detector is equal to or more than a specified value, the opening degree of the temperature control valve is set to a specified value. When locked, the lubrication temperature constant control automatically shifts to the lubrication temperature change operation, and when the alarm point of the lubrication temperature is exceeded, the set temperature is changed to increase the cooling water amount and the lubrication temperature constant control operation is performed again. A cooling water control device comprising a control device for maintaining the cooling water outlet temperature at a set temperature by operating in parallel with a spare cooling device when the cooling water temperature further rises. 2. A cooling water temperature detector is provided on the inlet side of the cooler, and a diagnostic device is provided for diagnosing a detection signal of the cooling water temperature detector based on a characteristic diagram showing cleanliness of the cooler. The cooling water controller according to claim 1.