JPH0436501A - Drain device for supply water heater - 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 and a feedwater heater drain system of a power generation plant, and in particular, to ensuring stable quality of water supply to a steam generator and heating the feedwater. This article relates to a feed water heater drain device that is most suitable for a system test device.

[Conventional technology]

A conventional feed water heater train device is a known example (Japanese Patent Application No. 1986-7).
3487). However, this has various problems, which will be explained with reference to FIG. Steam generated by the steam generator 1 is supplied to a high pressure turbine 2 and a low pressure turbine 3, and rotates a turbine generator 4. Steam exhausted from the turbine 3 is condensed in a condenser 5 to become condensate, and the condensate is passed through a low-pressure condensate pump 6, a condensate filtration device 7.
Condensate desalination bag! 8. High pressure condensate pump9. Low pressure water heater 1
0. Water pump 11. It passes through the high pressure feedwater heater 12 and returns to the steam generator 1 . On the other hand, the steam pumped from the middle of the high-pressure turbine 2 exchanges heat with the feed water in the high-pressure feed water heater 12 to become drain, is collected in the high-pressure drain tank 13, is pressurized by the high-pressure drain pump 14, and is sent to the inlet of the feed water pump 11. , directly collected.

Here, high pressure drain pump suction piping 15 before plant startup
．． To clean the high-pressure drain pump discharge pipe 16, condensate is sent from the condensate system to the high-pressure drain tank 13 via the condensate supply pipe 17, the high-pressure drain pump 14 is started, and the condensate is returned via the condensate pipe to the condensate feedwater recirculation pipe 18. By returning to the water container 5, the high pressure drain pump suction pipe 15. Remove dust from the high pressure drain pump discharge piping 16.

[Problem to be solved by the invention]

The condensate recovery system is generally installed after plant startup.

When the water quality of the feed water heater drain becomes good when the plant output is 50% or more, the drain pump is started and the drain from the drain tank begins to be collected into the condensate system. Therefore, the conventional feed water heater drain device has the following problems.

(a) Since it is not possible to remove metal corrosion products generated in the stagnant drain piping during the period from the start of the plant until the start of drain recovery, when starting drain recovery,
A large amount of corrosion products enters the steam generator. That is, after the plant is started, it is necessary to close the recirculation valve 19 of the condensate feedwater recirculation pipe 18 in order to supply condensate to the steam generator.

(b) When the feedwater heater starts operating after the plant is started up, a large amount of corrosion products in the body of the high-pressure feedwater heater 12 and the extraction steam piping from the turbine will drain into the high-pressure drain until the plant output reaches about 50%. It flows into the tank 31, and this flows into the high pressure drain pump suction pipe 15. These corrosion products flow into the high-pressure drain pump discharge piping 16 and become stagnant, so when the high-pressure drain pump 14 is started and drain recovery is started, a larger amount of corrosion products flows into the steam generator 1. If it flows into the steam generator 1, it will lead to serious problems such as corrosion damage to the internal structure of the steam generator, an increase in radiation dose due to activation of the corrosion products that have flowed in, and damage to the uranium fuel.

(C) In the conventional feedwater heater drain device, the low-pressure condensate pump 6 and the high-pressure drain pump 14 are operated during the cleaning operation before startup, which requires a large amount of operating power and makes the cleaning operation complicated. There was also one problem.

The purpose of the present invention is to eliminate the problem of a large amount of corrosion products flowing into the steam generator when the high-pressure drain pump is started and drain collection starts, to ensure a stable quality of water supplied to the steam generator, and to improve the quality of the water supplied to the steam generator. The purpose is to enable a system test of the feed water heater drain system before startup.

A feature of the present invention is that piping and valves are installed that can supply condensate from the condensate water supply system to the piping of the feedwater heater drain system during plant startup, shutdown, low load, etc. In other words, the drain in the piping from the drain tank to the drain injection point of the feedwater heater drain system is operated at a load of 50% or more, so in an operating mode of less than 50% load, it becomes stagnant water and metal in the drain piping. Corrosion occurs rapidly and when the drain pump is started, a large amount of corrosion products are supplied to the steam generator. In order to prevent metal corrosion occurring within the drain piping, condensate from the condensate water supply system is injected into the drain piping from the drain tank of the feedwater heater drain system to the drain injection point. This ensures a low flow rate in the drain pipe, prevents metal corrosion, and ensures stable water supply quality.

Additionally, during a system test of the feedwater heater drain system, condensate from the condensate water supply system can be sent to the drain pump suction pipe of the feedwater heater drain system, so condensate is continuously supplied to the feedwater heater drain system. can do.

This makes it possible to replenish the feedwater heater drain system at plant start-up, minimize radiation exposure, and enable system testing of the feedwater heater drain system under stable operating conditions.

The present invention is generally applicable to devices that immediately collect feedwater heater drain into a water supply system.

An example thereof is shown in FIGS. 1 and 2. steam generator 1
The steam generated enters the high-pressure turbine 2 to perform work, and is supplied to the low-pressure turbine 3 via the cross-around pipe 20, causing the turbine to rotate. Steam exhausted from the low pressure turbine 3 is condensed in a condenser 5 and becomes condensate. The condensate is supplied by a low-pressure condensate pump 6, a condensate filtration device [7, a condensate desalination device 8°, a high-pressure condensate pump 9. Low pressure feed water heater 10. Water pump 11. It passes through the high pressure feedwater heater 12 and returns to the steam generator l. 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 13, and the pressure is increased by a high-pressure drain pump 14, and the high-pressure drain pump discharge check valve 21. Via the high pressure drain tank water level adjustment valve 22,
The water is collected directly to the 11 population of the water supply pump. Further, the low pressure drain is collected in the low pressure drain tank 23, and the pressure is increased by the low pressure drain pump 24, and the low pressure drain is pumped up by the low pressure drain pump discharge check valve 27. The water is collected directly to the inlet of the condensate desalination system W8 via the low-pressure drain tank water level adjustment valve 28.

In the condensate feed water system and feed water heater drain system, high pressure condensate injection pipe 29. High pressure condensate injection valve 30. Low pressure condensate injection pipe 35. A low-pressure condensate injection valve 36 and the like are installed, and when the high-pressure drain pump 14 is stopped, condensate from the condensate water supply system is supplied to the high-pressure drain pump suction pipe 15 and the high-pressure drain pump discharge pipe 16. Condensate to the high-pressure drain pump suction pipe 15 is passed through the high-pressure drain pump suction pipe 15° and the high-pressure drain tank 13 through the high-pressure drain tank emergency piping 32. The water is then recovered to the condenser 5 by the high-pressure drain tank emergency regulating valve 33. Further, the condensate to the high pressure drain pump discharge pipe 16 is transferred to the high pressure drain pump discharge pipe 1.
6 to the inlet of the water supply pump 11 of the condensate water supply system,
The water level of the high-pressure drain tank 13 is maintained constant by the high-pressure drain tank emergency regulating valve 33 based on a signal from the high-pressure drain tank water level detector 34. Furthermore, while the low pressure drain pump 24 is stopped, condensate from the condensate water supply system is supplied to the low pressure drain pump suction pipe 25 and low pressure drain pump discharge pipe 26.6 Condensate to the low pressure drain pump suction pipe 25 is supplied to the low pressure drain pump suction pipe 25. It is recovered to the condenser 5 via the low pressure drain tank 23 by the low pressure drain tank emergency piping 32 and the low pressure drain tank emergency regulating valve 33. Further, the condensate is sent from the low-pressure drain pump discharge pipe 26 to the inlet of the condensate desalination device W8 of the condensate water supply system, and is supplied to the high-pressure condensate pump 9. Note that the water level of the low-pressure drain tank 23 is maintained constant by a low-pressure drain tank emergency regulating valve 41 based on a signal from a low-pressure drain tank water level detector 42 .

This allows the high pressure drain pump suction pipe 15. High pressure drain pump discharge pipe 16. Low pressure drain pump suction pipe 25. The low-pressure drain pump discharge pipe 26 ensures a minimum flow rate for preventing corrosion, and corrosion of the piping and equipment of the feed water heater drain system can be prevented. Thereby, the quality of the water supply can be stably ensured even when the high pressure drain pump 14 or the low pressure drain pump 24 is activated. Furthermore, since it is possible to control (fully open) the high pressure condensate injection valve 31 or the low pressure condensate injection valve 35 by the start signal of the high pressure drain pump 14 or the low pressure drain pump 24, stable condensate injection can be performed. can.

In addition, during a system test of the feedwater heater drain system, for example, in the case of a high-pressure feedwater heater drain, condensate from the condensate water supply system is transferred to the high-pressure drain via the high-pressure condensate injection pipe 29 and the high-pressure condensate injection valve 30. It is supplied to the pump suction pipe 15, and the high-pressure train pump 14 is operated at minimum flow. That is, the condensate flowing into the high-pressure drain tank 13 from the minimum flow pipe 38 is collected into the condenser 5 via the high-pressure drain tank emergency piping 32 and the high-pressure drain tank emergency regulating valve 33. Furthermore, the high pressure drain tank emergency regulating valve 33 is controlled by the signal from the high pressure drain tank water level detector 34, making it possible to maintain the water level of the high pressure drain tank 13 constant. This enables stable system testing of feed water heater train systems. In particular, the high pressure drain pump suction pipe 15
Since condensate is supplied to the drain pump 14 and the high-pressure drain pump 14 is operated at a minimum flow, it is possible to minimize the influence of temperature rise due to heat input to the drain pump.

Although condensate was extracted from the high-pressure condensate pump discharge pipe in this embodiment, it is also possible to extract the condensate from the condensate pump and from the condensate pipe of the steam generator. The same effect can also be achieved by installing piping to supply condensate and pure water from a make-up water system that supplies condensate and pure water to the power generation plant to the feedwater heater drain system other than the condensate water supply system. can get.

〔Effect of the invention〕

According to the present invention, it is possible to apply the feedwater heater drain of an atomic coupler plant or a thermal power plant to a condensate system, or directly to a drain system for recovery, and the following effects can be obtained.

(a) It is possible to remove metal corrosion products generated in the drain piping that is in a stagnant state between the time the plant is started up and the time when drain recovery is started.

(b) When the feedwater heater starts operating after the plant is started up, a large amount of corrosion products in the oil and steam piping will flow from the feedwater heater body and turbine into the drain tank until the plant output reaches about 50%. , which flows into the drain piping and becomes stagnant, can be removed and the corrosion products entering the steam generator when drain collection is started can be minimized.

As a result, corrosion damage to the internal structure of the steam generator and BW
In an R-atom couplant, it is possible to prevent an increase in radiation dose and damage to uranium fuel due to activation of inflowing corrosion products, improving the availability and reliability of plant operation.

(C) To solve the problem that in the conventional feed water heater drain device, the condensate pump and the drain pump are operated during the cleaning operation before startup, which requires a large amount of operating power and makes the cleaning operation complicated. I can do it.

(d) Furthermore, in the system test of the feed water heater drain system,
This can be performed by supplying condensate from the condensate water supply system to the drain pump suction pipe and running the drain pump in minimum flow mode, making system tests easier to operate and allowing system tests to be performed in a short period of time. Therefore, it is effective in shortening periodic inspection periods and reducing radiation exposure.

[Brief explanation of drawings]

1 and 2 show a system diagram of an embodiment of the present invention, and FIG. 3 shows a system diagram of a prior art. 1...Steam generator, 2...High pressure turbine, 3...
Low pressure turbine, 4... Turbine generator, 5... Condenser, 6... Low pressure condensate pump, 7... Condensate filtration device,
8... Condensate desalination device, 9... High pressure condensate pump, 10
...Low pressure feed water heater, 11...Water pump, 12.
...High pressure water heater. 13... High pressure drain tank, 14... High pressure drain pump, 15... High pressure drain pump suction piping, 16...
・High pressure drain pump discharge pipe, 17... condensate supply pipe,
Figure 1

Claims (1)

[Scope of Claims] 1. A condensate water supply system that sends water from a condenser of a power plant to a steam generator via a condensate purification device and a feedwater heater, and a drain of the feedwater heater that is connected to the condensate water supply system. In a feedwater heater drain system consisting of a device for direct recovery into the system and piping and valves connecting them, the piping of the condensate water supply system or the piping of the make-up water system of the power generation plant and the piping of the feedwater heater drain system or A drain device for a feed water heater, characterized in that it includes piping and a valve that connects to a drain tank, and piping and a valve that connects the drain tank to the condenser. 2. The feed water heater drain device according to claim 1, wherein a valve installed in a pipe connecting the pipe of the condensate water supply system and the pipe of the feed water heater drain system is controlled by the operating state of the drain pump.