JPS63294406A - Method and device for controlling feedwater of steam generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a condensate water supply system for a power plant, and more particularly to a water supply control method and apparatus for supplying stable water supply to a steam generator.

[Prior Art] Although there is a known example (Japanese Patent Application No. 59-227257) regarding a conventional water supply system to a steam generator, the problems of the conventional system will be explained with reference to FIG.

The steam generated in the steam generator 1 is passed through the main steam flow meter 2. The steam enters the high-pressure turbine 5 through the steam generator outlet valve 29 to perform work, and is supplied to the low-pressure turbine 8 through the cross-around pipe 6 and moisture separator 7 to rotate the turbine. Steam exhausted from the turbine is condensed in a condenser 9 and becomes condensed water. The condensate is pumped by the condensate pump 10. Condensate purification device 11. High pressure condensate pump 12, low pressure feed water heaters 13, 14, feed water pump 1
5. Returned to the steam generator 1 through the high pressure feed water heater 16. On the other hand, the steam extracted from the middle of the turbine exchanges heat with the feed water in the feed water heater and becomes drain (condensed water). The high-pressure drain is collected in a high-pressure drain tank 21, raised in pressure by a high-pressure drain pump 21, and directly collected at the water supply pump inlet via a high-pressure drain tank water level adjustment valve 23. Further, the low pressure drain is collected in the low pressure drain tank 25, the pressure is increased by the low drain pump 26, and the low pressure drain is directly collected into the high pressure condensate pump 12 via the low pressure drain tank water level adjustment valve 27.

Here, the water supply flow rate to the steam generator 1 is determined by the steam generator water level detector 18 so that the water supply water level in the steam generator 1 is constant.
It is controlled by the feed water control device 28 based on the measured values of the main steam flow meter 2 and the feed water flow meter 17. As a method of changing the water supply flow rate itself.

This is done by adjusting the rotation speed of the water supply pump 15 in accordance with a request signal from the water supply control device 28.

[Problems to be Solved by the Invention] In the water supply system of the prior art described above, the turbine generator 20
When the load is cut off or when the steam generator outlet valve 4 is erroneously closed, the water level in the steam generator 1 temporarily drops as shown in FIG. 2, so that a feed water flow rate of 80% to 100% is then required. However, in a water supply system equipped with a drain pump, the water processing capacity of the condensate pump 10 and purifier 11 is generally only about 60%, and since almost no steam flows into the turbine, there is no drain amount to the drain tank. , the amount of water injected into the drain becomes 0 (zero).

As a result, the condensate pump 10 and the high-pressure condensate pump 12 run out, and as the population pressure of the feed water pump 15 decreases, the feed water pump 15 stops (trips) to protect the feed water pump 15, and the water supply capacity is lost and the reactor There is a risk of scram (automatic stop).

An object of the present invention is to provide a water supply control device that can ensure water supply capacity even when steam generated by a steam generator does not enter a turbine during load cutoff or the like.

[Means for Solving the Problems] The present invention was made by studying in detail the water supply control of conventional power generation plants. By restricting the flow rate of the water supply pump, an excessive flow rate flowing into the condensate pump and the condensate purification device is prevented, and stable continuous water supply is achieved.

[Function] In the event of a sudden drop in output or a trip of the drain pump, the required population pressure of the water supply pump can be ensured, making it possible to supply stable water supply to the steam generator.

[Example] FIG. 1 shows an example. The steam generated in the steam generator 1 is passed through the main steam flow meter 2. The steam enters the high-pressure turbine 5 through the steam generator outlet valve 29 to perform work, and is supplied to the low-pressure turbine 8 through the cross-around pipe 6 and moisture separator 7 to rotate the turbine.

Steam exhausted from the turbine is condensed in a condenser 9 and becomes condensed water. The condensate is pumped by the condensate pump 10. Condensate purification device 11
．． High pressure condensate pump 12. The water is returned to the steam generator 1 through the low-pressure feedwater heaters 13 and 14, the feedwater pump 15, and the high-pressure feedwater heater 16. On the other hand, the steam extracted from the middle of the turbine exchanges heat with the feed water in the feed water heater and is drained (condensed water).
becomes.

The high-pressure drain is collected in a high-pressure drain tank 21, raised in pressure by a high-pressure drain pump 21, and directly collected at the water supply pump inlet via a high-pressure drain tank water level adjustment valve 23. Further, the low pressure drain is collected in the low pressure drain tank 25, the pressure is increased by the low drain pump 26, and the low pressure drain is directly collected into the high pressure condensate pump 12 via the low pressure drain tank water level adjustment valve 27.

Here, the water supply flow rate to the steam generator 1 is determined by the steam generator water level detector 18 so that the water supply water level in the steam generator 1 is constant.
It is controlled by the feed water control device 28 based on the measured values of the main steam flow meter 2 and the feed water flow meter 17. As a method of changing the water supply flow rate itself.

This is done by adjusting the rotation speed of the water supply pump 15 according to a request signal from the water supply control bag W128.

In a water supply system like the one mentioned above, for example, when the load of a turbine generator is cut off, there is no steam flowing into the turbine.
The drain pump outlet flow rate also decreases.

However, the water supply demand from steam generator 1 is transiently 80%~
Since it becomes 100%, the maximum flow rate will flow to the condensate pump and purification device, making it impossible to secure the necessary suction pressure at the water supply pump. Therefore, a low value selection device (selector) 50 is provided for the rotation speed control signal of the water supply pump, and a plant transient event detection signal 53 and a set flow rate signal generator 52 are provided. Then, when the maximum flow rate flows to the condensate pump or purification device, or in an event where the necessary suction pressure at the water supply pump cannot be secured, a plant transient event detection signal is activated and the outlet flow rate from the water supply pump is set in advance. limit the flow rate to less than the specified flow rate (maximum processing flow rate of the condensate purification equipment). In this way, it is possible to prevent an excessive flow rate of the condensate pump and the condensate purification device, and it is also possible to ensure stable suction pressure of the water supply pump.

FIG. 4 shows another embodiment. The idea of limiting the flow rate of the water supply pump is the same as in the first embodiment, but the signal from the flow meter 55 at the outlet of the drain pump and the signal from the preset flow rate signal generator 52 are added to the adding device 54. and add
This signal limits the flow rate signal of the water supply pump.

[Effects of the Invention] The present invention can be applied to water supply systems employing feed water heater drain pumps for atomic couplants and thermal power plants, and has the following effects.

1. In the event of a sudden drop in output or a drain pump trip, the required population pressure of the water supply pump can be ensured, making it possible to supply stable water supply to the steam generator.

2. Damage to equipment due to excessive flow rate of the condensate pump or condensate purification device can be prevented in the event of a sudden drop in output or a trip of the drain pump, improving the reliability of the water supply system.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the present invention, Fig. 2 is an explanatory diagram of a conventional water supply system, and Fig. 3 is an explanatory diagram of the characteristics of the water supply system during plant transition. DESCRIPTION OF SYMBOLS 1... Steam generator (abbreviated as SG), 2... Main steam flow meter, 3... Main steam pipe, 5... High pressure turbine, 7...
... Moisture separator, 8 ... Low pressure turbine, 9 ... Condenser, 10 ... Low pressure condensate pump, 11 ... Condensate purification device, 12 ... High pressure condensate pump, 13 .14...Low pressure feed water heater. 15... Turbine-driven feed water pump, 16... High pressure feed water heater, 17... Feed water flow meter, 18... Steam generator water level detector, 20... Generator, 21... High pressure drain Tank, 22... High pressure drain pump, 23... High pressure drain tank water level control valve, 25... Low pressure drain tank, 26... Low pressure drain pump, 27... Low pressure drain tank water level control valve, 28.・・Water supply control device, 29・
...Steam generator outlet valve, 50...Low value selection device (selector), 53...Plant transient event detection device, 52...Set flow rate signal generator, 55...Flow rate detector, 54... ...Flow rate signal addition device. Bleached 1Bl (S) Ministry of Procedure City Official Book (voluntary) Showa 6 animals 6 days 2 days

Claims (1)

[Claims] 1. Two or more condensate pumps that send water from a condenser to a steam generator in a power plant, two or more feed water pumps that are installed downstream of the condensate pump, and heat the feed water. In the condensate water supply system and heater drain system, which consist of a feedwater heater, a drain pump that directly collects the drain from the feedwater heater into the water supply system, and piping that connects them, transient conditions such as when the plant output suddenly decreases or when the drain pump stops, etc. A water supply control method for a steam generator, characterized in that the flow rate of a water supply pump is sometimes limited so that the flow rate of water supplied from the condensate pump is less than the water supply capacity of the condensate pump. 2. Two or more condensate pumps that send water from the condenser of the power plant to the steam generator, two or more feed water pumps that are installed downstream of the condensate pump, a feed water heater that heats the feed water, and feed water heating. In the condensate water supply system and heater drain system, which are composed of a drain pump that directly collects drain from the container into the water supply system, and the piping that connects them, the water supply pump A water supply control device for a steam generator, characterized in that the flow rate of the water is reduced to a preset flow rate or less. 3. Two or more condensate pumps that send water from the condenser of the power plant to the steam generator, two or more feed water pumps that are installed downstream of the condensate pump, a feed water heater that heats the feed water, and feed water heating. In the condensate water supply system and heater drain system, which are composed of a drain pump that directly collects drain from the container into the water supply system and piping that connects them, a flow rate detector is installed on the outlet side of the drain pump, and a flow rate detector is installed on the outlet side of the drain pump to detect the drain pump outlet flow rate and the specified flow rate. 1. A water supply control device for a steam generator, characterized in that a device is installed to add up the flow rate of the water supply pump, and a water supply pump outlet flow rate limiter is provided to prevent the outlet flow rate of the water supply pump from becoming larger than the total flow rate thereof.