JPS63294408A - Feedwater controller for 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 enters the high-pressure turbine 5 via the main steam flow meter 2 and the steam generator outlet valve 29, and performs work through the cross-around pipe 6. A low pressure turbine 8 is supplied through a 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.

c. Means for Solving Problems] The present invention was achieved through detailed study of water supply control in conventional power plants.

The feature of the present invention is that when the turbine output suddenly decreases such as during load cutoff or when the drain pump trips,
The stopped standby condensate pump is started, and another piping and control valve provided between the condensate pump outlet and the water supply pump inlet are operated.

[Function] The purpose is to ensure stable suction pressure to the water supply pump, prevent excessive flow to the condensate pump and condensate purification device, and ensure stable continuous 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 the 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 released 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. The method of changing the water supply flow rate itself is carried out by adjusting the rotation speed of the water supply pump 15 in accordance with a request signal from the water supply control device 28.

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, in the water supply system, a bypass pipe 50 communicating with the downstream side from the condensate pump outlet and a control valve 51 are provided in the middle thereof, and a control valve quick-opening device 53, a condensate pump standby machine start bag @54, and a plant transient event Detector 5
Install 3. Therefore, when the drain amount decreases due to turbine generator load cutoff or drain pump trip, etc., a signal from the plant transient event detector 53, a signal from the control valve quick opening device 53 and a condensate pump standby device starting device 54, Open the control valve 51 and also turn on the condensate pump 10 (or 12).
Activate the backup machine. In this way, the inlet pressure of the water supply pump can be ensured even during transient times, and stable water supply to the steam generator 1 can be ensured.

[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 drawings]

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 water pump, 16.
...High pressure water heater, 17... Water supply flow meter, 18...
・Steam generator water level detector, 20... Generator, 21...
・High pressure drain tank, 22...High pressure drain pump, 2
3...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, 5o... Bypass pipe, 51... Bypass control valve, 52
... Plant transient event detector, 53 ... Control valve quick opening device, 54 ... Condensate pump standby machine starting device. li! 1 hour (S)

Claims (1)

[Scope of Claims] 1. 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 installed downstream of the condensate pumps, and feed water heating. In the condensate water supply system and heater drain system, which are composed of a feedwater heater that collects water from the feedwater heater, a drain pump that directly collects drain from the feedwater heater into the water supply system, and piping that connects them, the connection between the condensate pump outlet and the water supply pump inlet is 1. A water supply control device for a steam generator, characterized in that another pipe and a control valve are provided in between, and the control valve is opened during a plant transition. 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 pumps, and a feed water heater that heats the feed water; In the condensate water supply system and heater drain system, which are composed of a drain pump that directly collects drain from the feed water heater into the water supply system, and piping that connects them, the condensate pump that is stopped is activated during plant transitions. Water supply control device for steam generators.