JPS6222998A - Control equipment for operation of cooling water system - Google Patents

Abstract

PURPOSE:To make possible a stable control of operation of cooling water system, by inputting detected values of ambient conditions, cooling water conditions, and operating state values of a plant into an automatic arithmetic unit, and by combining the number of operating fans of a cooling tower and blade angle of cooling water pumps (or the number of pumps) with each other. CONSTITUTION:Provided on cooling-water lines for inlet and outlet of a condenser, are temperature transmitters 17, 18 to detect temperatures of cooling- water and discharge-pressure transmitters 19a, 19b to detect flow rate of cooling- water. Further, transmitters 20a-20e, 21a and 21b are provided for motors for cooling tower fans and cooling water pumps to detect number of those in operation. On the other hand, a transmitter 22 is provided to detect atmospheric temperatures and wet-bulb temperatures. An automatic arithmatic unit 24, into which signals from each transmitter are inputted, is provided to select economical means of operation from present operating conditions and optimum operating conditions so that the optimum operation of a cooling water system is attained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention aims at optimal operation of a cooling water system in a power generation plant equipped with a cooling tower by controlling the temperature and quantity of cooling water. Regarding the operation control device.

[Background of the invention]

Generally, in thermal or nuclear power plants, steam that has expanded and performed work in a steam turbine is led to a condenser. This condenser cools and condenses the steam turbine exhaust into water.
It is a device that creates a high vacuum state, lowers the finger pressure, increases the heat drop in the steam turbine, and increases the turbine output and efficiency.

Seawater is generally used as the cooling water for this one-water tank, but this depends on the location of the power plant and other factors.

There are many cases where it is not possible to use seawater. At that time, water other than seawater, such as industrial water, is used as cooling water, but in the condenser, the temperature of the cooling water increases because it exchanges heat with the steam turbine exhaust gas described above.

Cooling towers are generally used as devices for cooling cooling water whose temperature has increased.

A typical cooling water system equipped with a cooling tower is shown in Figure 3. Steam generated from the boiler is input to a steam turbine 1, and the turbine exhaust gas 2, which has expanded and performed work, exchanges heat with cooling water in a condenser 3 and becomes condensate 4. Condensate 4 in the condenser 3 is pressurized by a condensate pump 5, heated by several stages of feed water heaters 6 and 7, and recovered to a deaerator. On the other hand, the pressure of the cooling water is increased from the water storage tank 8 by the cooling water pump 9 and sent to the condenser 3.

Due to heat exchange with the turbine exhaust gas 2 in the condenser 3, the temperature generally rises by 7° to 10C. The cooling water whose temperature has increased is sent to the cooling tower 10 and sprinkled thereon.

In the cooling tower 10, the looper 12 is
Air is introduced into the cooling tower 10, cooled by contact with the sprayed cooling water, stored in the water storage tank 8, and refluxed.

As mentioned above, since cooling towers exchange heat with the atmosphere, their cooling capacity is greatly influenced by outside air conditions. for example,
During the summer, when the atmospheric temperature rises, it will melt. Conversely, in the winter when the wet bulb temperature is low, the cooling water temperature is also low, resulting in operation in a relatively high vacuum. Therefore, there are many cases in which the steam turbine is forced to operate at a vacuum level higher than its limited vacuum level, resulting in extremely severe operating conditions for the steam turbine and having adverse effects (vibration, erosion, etc.). This high vacuum operation occurs not only in winter but also when the turbine exhaust gas is small during plant operation, and similar problems arise.

Furthermore, even during the same summer or winter season, it changes from moment to moment depending on the daily outside air conditions. As a result, the degree of vacuum in the condenser changes, causing fluctuations in turbine efficiency. Therefore, it is always difficult to operate at an efficient point.

Such drawbacks can naturally be considered even when seawater is used for cooling. However, as mentioned above, cooling water equipped with a cooling tower
Since the influence of outside air conditions is directly exerted on the cooling water, the frequency, change and influence of this drawback are very high. Furthermore, because the cooling water temperature is higher than seawater, the turbine design vacuum is usually set low (690 mHg for cooling towers,
In the case of seawater, the general design vacuum level is ld 722 mHg), so it is easy to meet the vacuum level limit.

On the other hand, various types of operation control in the cooling water system have been devised, and a typical one is to control the cooling water flow rate in order to obtain the condenser vacuum degree that gives the best turbine efficiency according to the load factor. To prevent environmental problems, there are drainage temperature control devices that keep the difference in temperature between cooling water intake and discharged water within a certain specified value.

However, these methods are based on adjusting only the amount of cooling water, and the means are a movable blade cooling water pump and a butterfly valve to adjust the water amount, and furthermore, a cooling water system that pursues economic efficiency. equipment costs have not been reduced.

Related devices of this type are disclosed in, for example, Japanese Patent Publication Nos. 59-53470 and 59-53471. [Object of the Invention] The object of the present invention is to The object of the present invention is to provide an operation control device for a cooling water system that evaluates economic efficiency and achieves optimal and stable cooling water operation.

[Summary of the invention]

Based on the basic idea that the degree of vacuum in the condenser changes depending on the cooling water temperature, flow rate, and turbine load factor, the present invention
The cooling water temperature is controlled by increasing or decreasing the cooling capacity depending on the number of operating fans in the cooling tower. In addition, based on the principle of controlling the cooling water flow rate by adjusting the blade angle (or number) of the cooling water pump, outside air conditions, cooling water conditions, and plant operation status values are detected, and the detected values are transferred to an automatic calculation device. This calculation device mutually combines the number of operating cooling tower fans and the angle (or number of cooling water pumps) of the cooling tower to achieve the most economical operation. It is characterized by operation control of the cooling water system for operation of cooling water.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. 1st
The figure is a configuration diagram of a system 0 that includes an example of an operation control device for a cooling water system configured to implement the present invention. The cooling water system configuration in this figure will be described by taking as an example a configuration in which the number of fans installed in the cooling tower is five and the number of cooling water pumps is two.

The plant operating status, cooling water operating status, and outside air conditions are input to an automatic calculation device using each detector, and the number of operating cooling tower fans and cooling water flow rate for optimal economical operation are calculated. By combinatorial operations! Determine the Dl appropriate economy/point and output it to the cooling tower fan and cooling water pump. The plant is operated using a load signal transmitter 14 in a generator 13.
is provided to detect the load of the generator, that is, the load factor of the steam turbine. Further, a pressure transmitter 15 is provided in the condenser 3 to detect the pressure inside the condenser, that is, the degree of vacuum of the condenser. Further, a flow rate transmitter 16 is provided at the condensate pump outlet,
The condensate flow rate, that is, the steam turbine exhaust flow rate is detected.

As for the cooling water operating state, a temperature transmitter 17 is provided in the condenser inlet cooling water line to detect the condenser inlet cooling water temperature, that is, the cooling tower outlet water temperature.

Further, a temperature transmitter 18 is provided on the condenser outlet cooling water line to detect the condenser outlet cooling water temperature, that is, the cooling tower inlet water temperature. In addition, the discharge pressure transmitter (19) of the cooling water pump 9
a, 19b) are provided to detect the cooling water flow rate. In addition, a transmitter (20a) is installed on the motor of the cooling tower fan and cooling water pump.
~20e.

21a and 21b) to detect the number of operating cooling tower fans and cooling water pumps.

On the other hand, a transmitter 22 is provided to detect atmospheric temperature and wet bulb temperature. In addition, as the control selection mode 23, a transmitter is provided to select two modes: high vacuum degree limit prevention operation and optimum vacuum degree operation.

An automatic calculation device 24 is provided that inputs the signals of each transmitter, performs a calculation to compare the current operating state and the optimum operating condition, calculates the number of operating cooling tower fans and the flow rate of cooling water, and calculates the combination of these. The most economical operation is determined and the output is sent to the cooling tower fan and cooling water pump motor to optimize the operation of the cooling water system.

FIG. 2 is a control diagram of an example in which the method of the present invention is implemented using the apparatus shown in FIG.

The automatic calculation device 24 includes a data input device section 251 , an operation-based vacuum degree calculation section 26 , a cooling tower fan operating number and power calculation section 27 , a cooling water flow rate and cooling water pump power calculation section 28
, comprehensive calculation section 29. Cooling tower fan operation number control unit 30,
It is composed of a cooling water flow rate control section 31.

First, signals from various transmitters are sent to the data input device section 25.
is input. The data input device section 25 inputs signals from the generator load transmitter 14 and signals from the condenser pressure transmitter 15 to input the plant operation status, cooling water operation status, and outside air conditions. P3. A signal F from the condensate flow rate transmitter 16 is input. In addition, the cooling water operating state is determined by the signal T's from the cooling tower outlet water temperature transmitter 17, the signal T's from the cooling tower inlet water temperature transmitter 1B, and the signal Pt from the cooling water pump discharge pressure transmitters 19a, 19b. .

P is input. Furthermore, a signal from an atmospheric condition transmitter (air temperature, wet bulb temperature) 22 around the cooling tower is input to the outside air condition. The input data to these data input device sections 25 is output to each calculation section.

The operation-specific vacuum degree calculation unit 26 calculates the prescribed condenser vacuum degrees for the high vacuum degree limited operation and the optimum vacuum degree operation, respectively, in the current cooling water operation state.

To obtain the specified degree of vacuum on each operation side, adjust the cooling capacity of the cooling tower and change the cooling water temperature to obtain the specified degree of vacuum.Control the number of operating cooling tower fans and change the operating point of the cooling water pump. This is carried out by combined control with cooling water flow rate control or by independent control.

The specified degree of vacuum in the operation-specific vacuum degree calculating section 26 is simultaneously sent to the cooling tower fan operating number and power calculating section 27 and the cooling water flow rate and cooling water pump power calculating section 28 . In the cooling tower fan operating number and power calculating section 27, the cooling tower outlet water temperature calculating section 32 calculates the condenser inlet cooling water temperature, the shim, and the cooling tower outlet water temperature that will give a specified degree of vacuum from the turbine displacement amount.

Furthermore, the actual cooling water flow rate calculating section 33 calculates the cooling water flow rate from the discharge pressure of the cooling water pump and the characteristic curve. or,
By the cooling tower inlet water temperature calculation unit 34.

The cooling tower inlet water temperature is determined by adding the temperature difference between the condenser cooling water inlet and outlet and the cooling tower outlet water temperature. Furthermore, the operating cooling tower fan number calculation unit 35 calculates the cooling tower performance using the number of fans that matches the cooling water flow rate and outside air conditions, and selects the number of operating fans that matches the cooling tower inlet/outlet water temperature.

The power calculation unit 36 calculates the fan power consumption based on the number of operating fans.

On the other hand, in the cooling water flow rate and cooling water pump power calculation unit 28, the planned cooling water flow rate calculation unit 37 calculates the planned cooling water flow rate for obtaining the condenser specified vacuum degree from the cooling tower outlet water temperature and the specified vacuum degree. . Based on the flow rate deviation between the planned cooling water flow rate and the actual cooling water flow rate calculation unit 33, the cooling water pump blade angle setting unit 38 sets the operation of the cooling water pump so that the planned cooling water flow rate and the actual cooling water flow rate are equal. do. After setting the operation, the power calculation unit 39 calculates the power consumption of the cooling water pump. In this example, the cooling water pump is a variable blade pump, but in the case of a fixed blade pump, it can be replaced with one unit. In this manner, the number of operating cooling tower fans, the flow rate of cooling water, and the power consumption thereof are input to the comprehensive calculation unit 29. This comprehensive calculation unit 29 compares the power consumption based on the power consumption of each control method, and determines whether to control one of them alone, or to control both by changing the number of operating fans and the flow rate of cooling water. We make various changes to find the most economical combination, make a comprehensive judgment on whether or not to use combined control, and decide on the optimal operation method.

The optimum operating method is outputted to the cooling tower fan operating number control unit 30 and the cooling water flow rate control unit 31, respectively, to the cooling tower fan and the cooling water pump.

By carrying out the above process, the optimal operation method for the cooling water system can be achieved.

According to this example.

(1) Taking advantage of the features of the cooling tower system. Combined control of the number of operating cooling tower fans to change the cooling water temperature and cooling water flow rate control makes it possible to maintain the condenser vacuum at an appropriate value, allowing for flexible cooling water operation. It has become possible.

(2) Although the cooling capacity of a cooling tower is greatly affected by outside air conditions, it has become possible to operate a cooling water system that is adapted to the outside air conditions.

(3) An economical control method using an automatic calculation device (combined control or independent control) enables the most efficient and economical optimum operation of the cooling water system. or,
This has made it possible to reduce operating costs for the cooling water system.

(4) From the perspective of improving turbine efficiency and protecting the turbine, the control mode is divided into high vacuum limited operation and optimal vacuum operation.
We were able to expand our operational range.

(5) Among the cooling water systems of general heat exchangers other than condensers,
The present invention can be applied to any system equipped with a cooling tower.Furthermore, as an application example of the control means based on the number of operating fans of a cooling tower, a system using a movable wing fan of a cooling tower, a fixed wing fan, etc. It is an operation control device that has a very wide range of applications, such as control means in combination with

〔Effect of the invention〕

According to the present invention, power consumption required for system operation can be reduced.

In addition, the operational status of the cooling water system can be constantly monitored.
In addition, operators are freed from complicated manual operations, and stable system operation is possible. By operating cooling towers that adapt to weather conditions, maximizing their cooling capacity, and collaborating with plant operations, the operational performance and reliability of the cooling water system and the power plant as a whole will be improved. .

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a system configuration diagram including an example of an operation control device according to the present invention, and FIG. 2 is a diagram of the control principle in the present invention.
Figure 3 is a typical cooling water system diagram equipped with a cooling tower. 16... Condensate flow rate transmitter, 17... Cooling tower outlet water temperature transmitter, 18... Cooling tower inlet water temperature transmitter, 19a. 19b...Cooling water pump discharge pressure transmitter, 20a-2
0e...Cooling tower fan motor, 21a, 21b.

Claims (1)

[Scope of Claims] 1. A condenser, a cooling tower equipped with a plurality of fans to cool the cooling water whose temperature has increased due to heat exchange with the condenser, and a cooling tower that cools the cooled water to the condenser. In a cooling water system equipped with a cooling water pump for sending water to a water heater and returning it to the cooling tower, plant operation is performed as a means for controlling the number of operating fans of the cooling tower and the blade angle or number of the cooling water pumps. A device is provided to detect the state value, cooling water operation state value, and outside air condition state value, and automatically perform calculations based on the detected values, and further includes a calculation circuit for the degree of vacuum of the condenser in the automatic calculation device. , and a calculation circuit for calculating the cooling water temperature, the cooling water flow rate, and the number of operating fans of the cooling tower to obtain the degree of vacuum, and further calculating the power of the operating fan of the cooling tower and the power of the cooling water pump. , a cooling water system characterized by being provided with an arithmetic circuit that selects a mutual operation method between the number of operating fans of the cooling tower and the operation of the cooling water pump that enables the most efficient and economical operation according to the power consumption thereof. System operation control device.