JPS5855322B2 - Power plant cooling water drainage temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a condenser cooling water drainage temperature control device in a power plant having a plurality of condensing steam turbine units.
In particular, the present invention relates to a cooling water drainage temperature control device suitable for obtaining a cooling water amount corresponding to the operating state of each steam turbine unit so as to suppress the temperature difference between cooling water intake and drainage in a power plant within a specified value.

In a power plant equipped with multiple displacement turbine units, cooling water is taken from a common water intake by the cooling water pump of each unit, reaches the condenser of each unit, and the temperature is increased by heat exchange with the turbine exhaust. After rising, it drains into a common drainage basin.

In this case, discharging wastewater whose temperature has risen excessively may cause thermal contamination of the sea, rivers, lakes, etc. near the drainage outlet.
The temperature rise of power plant cooling water must be kept below an appropriate value.

However, many conventional units are not equipped with an adjustment means to adjust the cooling water flow rate according to the load condition that changes from time to time. Even if the water drainage temperature rise is set to an appropriate value, the cooling water drainage of the entire power plant cannot be maintained at an appropriate value, and this is not satisfactory as a measure against thermal pollution of the entire power plant.

The present invention has been made in consideration of the above-mentioned current situation, and an object of the present invention is to improve the efficiency of the entire power plant even when only some of the plurality of turbine units are equipped with a cooling water flow rate adjustment device. An object of the present invention is to provide a cooling water drainage temperature control device capable of controlling the temperature rise of cooling water drainage to an appropriate value.

According to the present invention, control is performed so that the insufficient amount of cooling water in a turbine unit that is not equipped with a cooling water flow rate adjustment device is channeled into the cooling water system of a turbine unit that is equipped with a cooling water flow rate adjustment device.

An embodiment of the present invention will be described below.

FIG. 1 shows a cooling water system of a power plant to which a cooling water control device according to the present invention is applied.

In the figure, A, B, and N are condensing turbine units, respectively, and each unit's cooling water pump (
(hereinafter simply referred to as pumps) 2A, 2B, and 2N (hereinafter simply referred to as pumps) coolant water is supplied to each cold first ice tube and condenser valve 3A,
3B, 3N to each condenser 4A, 4B, 4N
The temperature of the cooling water increases by performing heat exchange commensurate with the load condition of each unit.

The waste water whose temperature has increased is discharged from the condenser outlet valves 5A, 5B, 5.
It reaches the drain port 8 through the N and cooling water pipe drain side.

At the drain outlet, the wastewater from each unit is mixed, and the temperature near the outlet becomes a weighted average temperature that takes into account the mass of the wastewater from each unit. It diffuses into the water.

Here, the cooling water system of units A and B is pump 2A.
, 2B is in operation, it takes in an almost constant amount of cooling water regardless of the load amount of each unit, but unit 1-N
By controlling the blade opening degree of the movable blade pump 2N, the amount of cooling water flowing through the cooling water pipe can be changed.

, in the cooling water systems of Units I-A and B, valves 3A or 5A in the same system, respectively.
The amount of cooling water flowing through the condenser can be changed by changing the opening degree of 3B or 5B, but it is extremely difficult to operate each valve in response to the constantly changing load conditions of each unit. Therefore, these valves 3A, 5
The opening degrees of A and 3B5B are always constant, that is, the amount of cooling water is constant.

Also, for the same reason, the valves 3N and 5N of Units I-N are operated at a constant opening, but the pump 2N of Units I-N is of a type that can adjust the blade opening. By adjusting the opening degree, the cooling water flow rate of the unit I-N can be adjusted in small steps, that is, in response to the load condition that changes from time to time.

Further, the cooling water system of Unit) N has a condenser bypass pipe 6 and a condenser bypass valve 7.

The bypass valve has the function of changing the ratio of the flow rate of cooling water flowing through the condenser side and the bypass pipe 6, and automatically or manually operates the volume valve to prevent excess cooling water that cannot flow into the condenser 4N. This allows the flow of the water to the bypass pipe 6.

FIG. 2 shows an embodiment of the power plant cooling water drainage temperature control device according to the present invention.

In the same figure, the signal set by the intake water temperature difference setting unit 21 is transmitted to the intake water temperature detection unit 22, the water outlet temperature detection unit 2
The actual temperature difference calculated by the intake/water temperature difference calculating section 24 which receives the signal from 3 is input to the deviation calculating section 25, and a temperature difference deviation signal is obtained.

The temperature difference deviation signal is subjected to processing such as setting a dead band suitable for the control system, integrating to a first-order delay, dead time, etc., and converting it into a cooling water amount commensurate with the temperature difference deviation in the temperature difference deviation signal processing calculation unit 26. , a signal of the amount of cooling water to be increased or decreased in response to the temperature difference deviation is obtained.

This signal is added to a cooling water flow rate advance command signal, which will be described later, in an adder 35, and is added to a cooling water flow rate command signal processing section 3.
6, the control etc. according to various conditions of the plant and power plant equipment are performed to obtain the actual command value for the cooling water amount, and further, in the subtracter 37, the difference between the cooling water amount of the unit N and the actual flow signal from the detection unit 38 is calculated. is determined and a deviation signal is obtained.

This signal is converted into a pump blade opening command value commensurate with the cooling water flow rate command by the pump blade opening calculating section 39, and the subtractor 4
2, the deviation from the actual opening signal from the pump blade opening detection section 47 is obtained.

This deviation becomes a blade drive signal by the pump blade drive circuit unit 43, and the pump blade drive unit 46 is controlled so that the required blade opening is achieved.

Reference numeral 40 denotes a pump blade opening degree signal switch, and when it is in the position shown in the figure, manual setting can be performed using a pump blade opening degree setting device 41.

Reference numeral 44 denotes a pump blade opening degree control device 44, which can be manually operated by a pump blade control device 45 when in the illustrated position.

The above-mentioned intake and water temperature difference setting section 21. Intake water temperature detection unit 22,
Drainage temperature detection section 23, intake and drainage temperature difference calculation section 24, deviation calculation section 25, temperature difference deviation processing calculation section 26, cooling water flow rate command signal processing section 36, subtractor 37, cooling water amount detection section 38, pump blade opening degree The calculation unit 39, subtractor 42, pump blade drive circuit unit 43, pump blade drive unit 46, and pump blade opening detection unit 47 convert the actual temperature difference into a temperature based on the actual temperature difference between the cooling water intake and the drainage water. The cooling water flow rate is adjusted to match the target difference value.

However, simply adjusting the cooling water flow rate based on the actual temperature difference as described above causes the following problems.

In other words, the cooling water piping from the water intake to the water outlet generally has a long distance and a large system delay, so it is not possible to perform control in response to turbine load fluctuations, etc. using only signals based on the temperature difference between the intake and the water. .

For this purpose, it is necessary to include preceding elements corresponding to the operating conditions.

The temperature rise of cooling water is determined by the amount of heat exchanged by the condenser based on the turbine load and the flow rate of cooling water, so the flow rate of cooling water to maintain the temperature rise at the specified value is determined by the amount of heat exchanged by the condenser, which determines the amount of heat exchanged by the power generation. It is given as a function of machine power.

Here, since the amount of cooling water in unit A and unit B in Fig. 1 is a constant flow rate regardless of the load of each unit, the cooling water flow calculated as a function of the output of the generator of each unit and the amount of cooling water in each unit are If the difference between the flow rate of the cooling water and the flow rate of the cooling water actually flowing through the cooling water system is sent to the cooling water system of the unit N, the temperature rise of the power plant cooling water at the drain can be brought to a specified value.

In FIG. 2, the output of the generator of unit A is detected by the unit A generator output detection section 27, and this detected value is supplied to the cooling water shortage flow rate calculation section 30 for unit A.
Here, from the operating state of the generator in unit A (that is, according to the amount of heat exchanged by the condenser), the flow rate of cooling water required to bring the temperature rise of the waste water in unit A to the specified value and the actual flow rate of cooling water are calculated. (If the actual cooling water flow is in excess, the underflow value will be negative.)

). Similarly, the output of the generator in unit B is
Units l-B detected by the generator output detection unit 28
Based on the operating state of the generator of unit B, a cooling water shortage flow calculation section 31 generates a signal indicating the insufficient flow of unit B.

The output of the generator of unit N is detected by the generator output detection section 29 for unit t-N. This detected value is supplied to the required cooling water flow rate calculation section 32 for unit 1-N. A signal is generated that indicates the flow rate of cooling water necessary to bring the temperature rise of the waste water of the unit N to a specified value from the viewpoint of the operating state of the machine.

The cooling water shortage flow rate of units A and B and the required cooling water flow rate of unit t-N are added in an adder 33, and the cooling water system of unit N is added in order to bring the temperature difference between intake and drainage to a specified value for the entire power plant. A signal is obtained indicating the amount of cooling water that should flow.

This signal is sent to the advance signal processing section 34, where limitations or biases based on equipment conditions on the plant side of units I-H, load fluctuation conditions of each unit, etc. are added to obtain a advance signal regarding the cooling water flow rate.

This advance signal is added in the adder 35 to the above-mentioned signal of the cooling water flow rate to be increased or decreased in accordance with the temperature difference deviation.The result of this addition is used as the cooling water flow rate command signal in the cooling water flow rate command signal processing unit 36. can be conveyed to.

In this way, by taking into account the operating conditions of the generators in Unit A and Unit B and adjusting the cooling water flow rate of Units I-N, it is possible to maintain the temperature difference between intake and drainage water throughout the power plant to the specified value. Control takes place.

In addition, when calculating the cooling water flow rate corresponding to the operating status of the generator, even more accurate calculations can be achieved if the cooling water temperature, condenser vacuum level, etc. are used as calculation conditions in addition to the generator load signal. can.

Furthermore, if there are multiple pumps or piping systems, it is necessary to use multiple circuits to control the corresponding control device.

Furthermore, it is also effective to calculate the cooling water flow rate based on an expected load command that matches the response of the control system.

Furthermore, in the above embodiment, a single unit N (normally, in one steam turbine facility, a so-called single unit consisting of a pair of three condensers is often used).

), the cooling water flow rate was adjusted only for
When two or more units are equipped with cooling water flow rate adjusting means, the cooling water flow rate of the two or more units may be adjusted to compensate for the insufficient flow rate of cooling water in other units.

As described above, according to the present invention, the cooling water flow rate of the cooling water system of some of the plurality of condensing turbine units of a power plant having a plurality of condensing turbine units is automatically adjusted. By doing so, it is possible to control the temperature difference between the intake and drainage water of the entire power plant 0-) to an appropriate value.

In particular, if you have an existing unit that makes it difficult to change the cooling water flow rate frequently, and it becomes necessary to keep the intake and drainage temperature below a certain value, you can install a new unit or replace the existing unit. By modifying one of these units, it will be possible to control the cooling water drainage temperature for the entire power plant.

Furthermore, by adopting this device, no more cooling water than is required is flown, which eliminates waste of pump power and is effective in saving energy within the power plant.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a power plant cooling water system having a plurality of condensing steam turbine units to be controlled by an embodiment of the present invention, and Fig. 2 is a block diagram showing a control device according to an embodiment of the present invention. It is. 1... Water intake, 2N... Movable blade cooling water pump for unit N, 4A, 4B, 4N... Condenser, 8... Drain port , 21... Intake water temperature difference setting section, 22... Intake water temperature detection section 23.
... Drainage temperature detection sound doctor 26 ... Temperature difference deviation signal processing calculation section, 27 , 28 . 29... Generator output detection section, 30.31...
...Cooling water shortage flow rate calculation unit, 32...Cooling water shortage flow rate calculation unit 34...Advance signal processing unit, 3
6...Cooling water flow rate command signal processing unit.

Claims (1)

[Claims] 1 Based on the actual temperature difference between intake and discharge of cooling water in a power plant having a plurality of turbine units, some turbine units among the plurality of turbine units are adjusted to match the actual temperature difference with the temperature difference film constant value. a temperature difference/deviation processing calculation unit that calculates the flow rate of cooling water that should flow into the cooling water system; and a temperature difference processing unit that calculates the flow rate of cooling water that should flow into the cooling water system; a cooling water required flow rate calculation unit that calculates the required flow rate of cooling water necessary for the operation of the turbine unit, and a cooling water required flow rate calculation unit that calculates the required flow rate of cooling water necessary for the operation of the turbine unit, and a turbine unit other than the some of the turbine units based on the amount of heat exchanged in the condenser of the turbine unit other than the some of the turbine units. a cooling water shortage flow rate calculation unit that calculates a cooling water shortage flow rate that is insufficient to bring the wastewater temperature rise to a predetermined value; and a cooling water shortage flow rate calculation unit that performs signal processing based on plant conditions, etc. on the sum of the cooling water required flow rate and the cooling water shortage flow rate. and a preceding signal processing unit that obtains a preceding signal based on the preceding signal and the cooling water flow rate calculated in the temperature difference deviation processing calculation unit, and adjusting the cooling water flow rate of the some of the turbine units. Power plant cooling water drainage temperature control device that controls the temperature of cooling water drainage.