JPS6112195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling water flow rate control device for supplying cooling water to a condenser of a thermal or nuclear power plant.

Generally, in thermal and nuclear power plants, steam that has expanded in a steam turbine and completed its work is led to a condenser, where it is cooled and condensed to become water, and the inside of the condenser is kept in a high vacuum state to create back pressure. lower the
The heat drop in the steam turbine is increased, increasing the output and efficiency of the turbine. In such a condenser, a degree of vacuum is calculated so that the condenser can be operated at the best efficiency according to the load factor of the turbine, and a cooling water flow rate control device maintains this degree of vacuum.

Seawater is generally used as the cooling water for such condensers, and after exchanging heat with the turbine exhaust, it is discharged into the sea again. However, the temperature of the wastewater is higher than the temperature of the nearby seawater, which causes various adverse effects, so it has become a social responsibility to maintain this temperature increase within a predetermined range.

Figure 1 is a diagram showing the cooling water circulation system of the condenser. Cooling water at water intake 1 is pumped up by circulating water pumps 2A and 2B, and a part of it is pumped up by the condenser inlet valves 3A and 3B. The opening of the condenser inlet valves is adjusted by electric motors 4A and 4B, which adjusts the flow rate of cooling water to the condenser. The degree of vacuum in the vessel and the temperature of the waste water are controlled.

In this way, the cooling water that has entered the condenser water chambers 5A and 5B exchanges heat with the exhaust gas of the steam turbine 7 while passing through a group of cooling pipes (not shown) in the direction of the solid line arrow, and the cooling water warmed here passes through the drain port 8. is released.

On the other hand, the remaining cooling water pumped up by the circulating water pump and supplied to the condenser is
The water passes through condenser bypass valves 9A and 9B whose valve openings are adjusted by electric motors 10A and 10B, is mixed with the aforementioned condenser waste water, and is discharged to drain port 8. Here, the sum of the condenser drainage amount and the condenser bypass flow rate is used as the cooling water flow rate, and is detected by the flow rate detectors 11A and 11B.

In the above cooling water system, the condenser bypass valves 9A and 9B are normally fully closed, and the condenser inlet valve 3
The degree of vacuum in the condenser and the temperature of the drain water are controlled by adjusting the openings of A and 3B. For example, the condenser inlet valve and the condensate temperature are The capacity of the cooling pipe is designed. Additionally, it is common that a flow rate of cooling water greater than the flow rate required to obtain the optimum degree of vacuum in the condenser is required to control the drainage temperature, and in practice, a large amount of cooling water is supplied to the condenser. The cooling effect increases, and the heat drop increases accordingly, resulting in a significant improvement in turbine efficiency.

However, in order to control the difference between the water intake (seawater temperature) and the wastewater temperature to a constant level, thermal wastewater temperature control takes into consideration changes in seawater temperature, turbine load conditions, and wastewater temperature measurement points (where it joins the wastewater from other turbines). In some cases, the maximum flow rate that can flow into the condenser may be exceeded.

In such conventional equipment, operators monitor the vacuum level of the condenser and manually operate the condenser bypass valve to maintain the temperature of the heated wastewater within a specified range. The drawback is that it requires a lot of effort for the operator to keep up with various changes in mouth temperature, etc., and is also low in reliability.

The present invention has been made to eliminate the above-mentioned drawbacks, and is a condenser that automatically adjusts the opening of the condenser bypass valve when the cooling water flowing in the condenser exceeds the rated flow rate. The purpose is to provide a cooling water flow rate control device.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a block diagram showing the configuration of a cooling water flow rate control device according to the present invention. Among cooling water systems A and B, the control device for system A is shown as 100, and the same system is also used for system B. It will be done. 101
is a flow rate setting circuit that calculates the flow rate setting value _Q1 from the turbine load factor, water intake seawater temperature, etc., 10
2 is an adder that calculates the sum of the condenser flow rate and the condenser bypass valve flow rate (hereinafter referred to as total actual flow rate) between the value _Q2 detected by the flow rate detector 11A and the aforementioned flow rate set value _Q1 . 103 is a flow rate command circuit that calculates the difference Q _3. Based on the difference signal Q ₃ , the condenser flow rate and condenser bypass are calculated by taking into consideration cooling pipe delay, flow loss, flow rate change rate restriction, etc. 104 is the condenser inlet valve flow rate command device that outputs the total value (hereinafter referred to as the total flow rate command value) Q ₄ with the valve flow rate. 105 is a condenser bypass valve flow rate command device that outputs a flow rate command value Q ₅ that is proportional to the aforementioned total flow rate command value Q ₄ and is limited to a constant value thereafter. 106 outputs the increased amount of water when it exceeds the maximum flow rate, that is, the flow rate command value Q ₆ to be sent to the bypass pipe, and 106 is the condenser side flow rate command value Q ₅ as the condenser inlet valve opening value. A _condenser inlet valve opening converter 107 converts the opening degree η of the opening detector 12A of the condenser inlet valve 3A to an adder 107.
₂ and the condenser inlet valve opening value η ₂ , the difference signal η ₃
, and 108 is a condenser inlet valve opening degree regulator which adjusts the condenser inlet valve opening degree adjusting motor 4A based on the difference signal η ₃ to adjust the condenser inlet valve opening degree.

In addition, 109 is the condenser bypass side flow rate command value
A condenser bypass valve opening converter converts Q ₆ into a condenser bypass valve opening value η ₄ ; 110 is an adder that converts the opening η ₅ of the condenser bypass valve opening detector 13A and the condenser bypass valve opening value η 4; 111 is a condenser bypass valve opening regulator which adjusts the condenser bypass valve opening regulating motor _10A based _on the difference signal _η6 . to control the condenser bypass valve opening.

The operation of the cooling water flow rate control device of the present invention configured as described above will be explained.

First, the flow rate setting circuit 101 calculates the flow rate setting value Q ₁ from the turbine load factor, cooling water temperature, heated wastewater temperature setting values, etc., and the difference Q ₃ from the total actual flow rate Q ₂ is determined by the adder 102. and this difference signal Q ₃
Based on this, the flow rate command circuit 103 outputs a total flow rate command value Q ₄ that takes into account cooling pipe delay, flow loss, flow rate change rate restriction limited from the cooling pipe, and the like.

When this total flow rate command value Q ₄ is relatively small, the same signal Q ₅ as this command value Q ₄ is output from the condenser inlet valve flow rate controller, but the total flow rate command value
If Q ₄ becomes large and exceeds the amount limited by the condenser inlet valve and condenser cooling pipe, it will not be possible to supply enough cooling water to the condenser to match this total flow rate command value. In this state, although the degree of vacuum in the condenser can be maintained sufficiently, the temperature difference between the intake side and the discharge side of the cooling water cannot be maintained within a specified range. In order to cope with such a situation, a condenser bypass valve flow rate controller 105 is provided to lower the discharge temperature by passing a necessary amount through the condenser bypass valve beyond the amount that can be recycled through the condenser.
Therefore, at the point where the output of the condenser inlet valve 104 reaches the maximum point, the bypass pipe flow rate command value Q ₆ is outputted from the condenser bypass valve flow rate command device 105. Valve opening values η ₁ and η ₄ corresponding to these flow rate command values Q ₅ and Q ₆ are output from the condenser inlet valve opening regulator 108 and the condenser bypass valve opening regulator, respectively. The output of is compared with the detection value of each valve opening degree detector, and the condenser inlet valve 3A and the condenser bypass valve 9A are controlled by an amount corresponding to the difference. Thereby, an appropriate amount of cooling water can be supplied in response to fluctuations in the generator load and the temperature on the seawater intake side.

In addition, in the above example, the flow rate command circuit is calculated based on the total flow rate of the condenser side and the bypass side, but the condenser side and the bypass pipe side are provided separately, and this part is divided into two systems. The opening degree of each valve may be adjusted.

As is clear from the above description, according to the cooling water flow rate control device of the present invention, the opening degree control of the condenser bypass valve is automatically performed, reducing the burden on the operator and relying on the operator's judgment. It is possible to prevent erroneous operations caused by dripping and improve operational efficiency and reliability. Furthermore, until the condenser bypass valve is opened, more cooling water is required to control the drain temperature than is required to maintain the optimum vacuum level in the condenser, so this excess cooling water is By passing through the chamber, the degree of vacuum is further improved and efficiency is also increased.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of the circulation of cooling water in a condenser, and FIG. 2 is a block diagram showing the configuration of a cooling water flow rate control device for a condenser according to an embodiment of the present invention. 1...Water intake, 2A, 2B...Circulating water pump,
3A, 3B... Condenser inlet valve, 4A, 4B... Electric motor, 5A, 5B... Condenser water chamber, 6... Condenser, 7... Steam turbine, 8... Drain port, 9A,
9B... Condenser bypass valve, 10A, 10B...
Condenser bypass valve opening adjustment motor, 11A, 11
B...Flow rate detector, 101...Flow rate setting circuit, 1
02, 107, 110... Adder, 103... Flow rate command circuit, 104... Condenser inlet valve flow rate commander, 105... Condenser bypass valve flow rate commander, 1
06... Condenser inlet valve opening converter, 108... Condenser inlet valve opening regulator, 109... Condenser bypass valve opening converter, 111... Condenser bypass valve opening adjustment vessel.

Claims (1)

[Claims] 1. In a cooling water flow control device for a condenser where a part of the cooling water circulates through the condenser through the first valve, mixes with the remaining cooling water that passes through the second valve, and is discharged. , a flow rate command circuit that outputs a total cooling water flow rate signal based on the difference between a set value of the amount of cooling water calculated using the turbine load factor and the water intake temperature and the actual amount of cooling water; and a flow rate command circuit that circulates the condenser. A first circuit that allows the output of the flow rate command circuit to pass when the amount of cooling water is below the upper limit.
a second flow rate command device that outputs only an excess amount of cooling water that the output of the flow rate command circuit exceeds the upper limit of the amount of cooling water circulating through the condenser; Cooling of a condenser configured to adjust the opening degree of the first valve according to the output of the device, and adjust the opening degree of the second valve according to the output of the second flow rate command device. Water flow control device.