JPS6054595B2 - Cooling water flow control device - Google Patents

Description

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

The thermal efficiency of a turbine is determined by both thermal cycle conditions such as the conditions of steam generated from the boiler, the degree of vacuum of the condenser, the feed water temperature, and the number of feed water heating stages, and the performance of the turbine body.

The present invention relates to the degree of vacuum in the condenser during the thermal cycle conditions. In a typical thermal or nuclear power plant, steam that expands in a turbine and performs work is led to a condenser. The action of the condenser is to cool and condense the exhaust gas from the turbine, create a high vacuum, lower exhaust pressure, and increase the heat drop of the steam turbine to increase turbine output and efficiency. In this case, the degree of vacuum in the condenser changes depending on the exhaust volume of the turbine led here, the exhaust temperature, the temperature and flow rate of the cooling water that cools the condenser, the cooling surface area of the condenser, etc. It is.

The optimum degree of vacuum for such a condenser is determined based on the requirement for maximum efficiency operation depending on the turbine load. Conventionally, seawater has been used as cooling water for condensers in thermal power and nuclear power plants, and the amount of cooling water that can be supplied is such that the optimum vacuum level can be achieved based on the average seawater temperature throughout the year and the average turbine load factor. In many cases, the amount of cooling water was designed and fixed at the time of construction of the power plant, and in rare cases, when the temperature of the cooling water changed significantly, the amount of cooling water was manually changed by the operator seasonally.

The cooling water system of the condenser in which this operation is performed is shown in FIG. In Fig. 1, cooling water taken in from water intake 1 is supplied to the condenser through two systems; first, it is pumped up by circulating water pumps 2A and 2B, and then pumped through condenser inlet valves 3A and 3B. pass.

The opening degree of this condenser inlet valve can be adjusted by electric motors 4A and 4B. Next, the cooling water that has passed through this condenser inlet valve enters the condenser water chambers 5A and 5B, and while passing through a group of cooling pipes (not shown) of the condenser 6 in the direction of the solid line arrow, it is connected to the exhaust gas of the steam turbine 7. The hot water heated by the heat exchange is sent to the discharge port 8. Here, 9 is a cooling water inlet temperature detector, and IOA and IOB are condenser inlet flow rate detectors. In this conventional cooling water flow rate control device, an operator constantly monitors the inlet temperature and condenser inlet flow rate and operates the aforementioned condenser inlet valves 3A and 3B to maintain the optimum degree of vacuum in the condenser. However, most of the openings were set at a constant average opening throughout the year.

However, as we are forced to save energy resources these days, more efficient turbine operation is required.
In order to meet this requirement, fluctuations in the turbine load must also be taken into account, and the above-mentioned manual operation of controlling the cooling water flow rate has its limitations and has the drawback of not being sufficiently effective.

The present invention has been made to eliminate the above-mentioned drawbacks.
The purpose of the present invention is to provide a cooling water flow rate control device that always optimally controls the degree of vacuum in a condenser so that turbine efficiency is maximized. As mentioned above, the degree of vacuum in the condenser depends on the exhaust volume of the turbine led here, the exhaust temperature, the temperature and flow rate of the cooling water,
It changes depending on the cooling surface area of the condenser, etc. Among these, the turbine displacement is proportional to the turbine load.
The exhaust gas temperature is generally a constant temperature, and the cooling surface area of the condenser is also a fixed value.

Therefore, it is clear that the amount of condenser cooling water to obtain the optimum degree of vacuum is determined as a function of the generator output and the cooling water temperature. FIG. 2 is a block diagram showing the configuration of an embodiment of a cooling water flow rate control device according to the present invention, in which 11 is a power detector, 100 is a cooling water flow rate control device, 101 is a flow rate command value generator, and 102 and 103 are Adder, 104 and 1
Reference numeral 05 indicates a regulator, and the same reference numerals as those in FIG. 1 indicate the same elements.

In FIG. 2, the flow rate control device 100 controls the inlet temperature. A signal G1 proportional to the cooling water inlet temperature T1 measured by the temperature detector 9 and the generator output detected by the power detector 11
is given.

These signals T1 and G1 are given to a flow rate command value generator, which generates a flow rate command value for obtaining the optimum degree of vacuum of the condenser. A water container cooling flow rate is calculated and a signal Q1 corresponding to this flow rate is provided to adders 102 and 103. These adders combine the flow rate signal Q1 with the inlet flow rate signal Q of the condenser cooling water detected by the flow rate detectors 10A and 10B.
Differences Qε1 and QE2 from al and Qa2 are obtained and provided to regulators 104 and 105. Here, regulator 1
04 and 105 drive the condenser inlet valve motors 4A and 4B so that the deviations Qε1 and QE2 become zero, and adjust the opening degrees of the condenser inlet valves 3A and 3B to control the flow rate of the condenser. It can be controlled. That is, the amount of cooling water in the condenser is determined as a function of the generator output and the cooling water temperature, and a flow rate of this value is supplied, so that the optimum degree of vacuum can be obtained for the condenser. In the above embodiment, the flow rate at the condenser inlet is controlled, but equivalent results can be obtained by controlling the flow rate at the condenser outlet or the flow rate of the circulating water pump. Although the circuit is calculated based on the flow rate signal, it can be similarly configured with control targeting the opening degree of the condenser inlet valve. As is clear from the above explanation, according to the cooling water flow rate control device of the present invention, factors that change the optimum degree of vacuum of the condenser are input, so that the optimum degree of vacuum can always be obtained according to external conditions. Since the amount of cooling water is controlled, the thermal efficiency of the turbine is improved, making effective use of energy resources and saving labor for operators.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional system for cooling a condenser, and FIG. 2 is a block diagram showing the configuration of a cooling water flow rate control device according to an embodiment of the present invention. 1...Water intake, 2A, 2B...Circulation pump, 3A, 3B...Condenser inlet valve, 4A, 4B
......Electric motor, 5A, 5B...Condenser water chamber, 6...Condenser, 7...Steam turbine, 8...・Drain port, 9... Inlet temperature detector, 10A, 10B... Flow rate detector, 11.
... Power detector, 100 ... Cooling water flow rate control device, 101 ... Flow rate command value creator, 10
2,103... Adder, 104,105...
...Adjuster.

Claims (1)

[Claims] 1 In a cooling water flow rate control device in which the cooling water flow rate of a condenser can be changed by an electric valve, there is provided a flow rate command value generator that calculates the optimum cooling water flow rate according to the water temperature at the water intake and the turbine load, and this flow rate command value. and a regulator that controls the electric valve so as to zero the deviation of the output of the generator and the flow rate of the cooling water, and adjusts the condenser to the optimum level in response to fluctuations in the water temperature of the water intake and the turbine load. A cooling water flow rate control device that operates a turbine while maintaining a degree of vacuum.