JPS6044553B2 - Rust prevention methods and equipment for supply and condensate piping systems - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rust prevention method and apparatus for a feed/condensate piping system of a power generation facility.

Generally, a nuclear power generation facility using, for example, a boiling water reactor is constructed as shown in FIG.

That is, A is a boiling water type nuclear reactor, and the steam generated in this reactor A is sent to a turbine C via a main steam pipe B, drives a generator D, and is condensed in a condenser E. It becomes condensate. This condensate is then sent to the reactor A via a series of feed/condensate piping systems F. This feed/condensate piping system F is connected to the condensate pump G), which is arranged sequentially from the condenser E side, to the air extractor H, the grand steam condenser I, the condensate desalination equipment J, and the condensate boost pump). A group of feed water heaters L.
..., reactor feed water pump M, feed water heater N, and piping 0 connecting these. Also, the water level of condenser E is the same as that of condensate storage tank P and control valves Q and R.
It is configured to be controlled by. by the way,
When facilities such as periodic inspections are shut down for a long period of time, rust occurs on the grafted parts of the supply and condensate piping systems, and when operation starts, this rust flows into reactor A and becomes radioactive, forming what is called radioactive cladding. There was a problem in which radioactive substances circulated within the facility, causing radioactive contamination to the entire facility. For this reason, conventionally, when equipment is to be stopped for a long period of time, water mixed with a rust preventive agent is injected into the supply/condensate piping system F to fill it with water to prevent estrus, so-called full-water storage. . However, such full water storage requires draining the water in the supply/condensate piping system F (7) when modifying or repairing equipment, piping, etc. Water containing anti-corrosion agents had to be reprocessed to prevent environmental pollution, which caused problems that made the work extremely troublesome.Also, as shown in Figure 1, the water supply and
An air valve S is installed at the high part of the condensate piping system F, that is, at the top.
..., and a drain valve T at the lower part, that is, the bottom.
......, and when the equipment is to be stopped for a long period of time, these air valves S... and drain valves T...
When opened, the water in the supply/condensate piping system F is discharged by gravity from the drain valve T, and the water is drained into the drain tray U.
So-called dry storage is carried out in which the waste is collected and processed in the waste treatment equipment V via... This dry storage has a greater rust prevention effect than the above-mentioned full water storage, and also makes it easier to modify and repair the supply/condensate piping system F(7) equipment and piping, but the waste treatment equipment Because of the limited capacity of the system, it takes a long time to drain the water, and by the time the water drain is completed, the supply/condensate piping system F has cooled down to about the outside temperature. For this reason, it is difficult to naturally dry the moisture remaining in the supply/condensate piping system F, and conventionally, hot air is supplied to the supply/condensate piping system F after drainage is completed to remove the remaining moisture. Remove moisture and dry. As a result, it takes a long time to complete the work, and there are parts of the supply/condensate piping system F where warm air does not flow sufficiently, making it difficult to dry completely and making it impossible to obtain sufficient rust prevention effects. There was a problem. The present invention has been made based on the above circumstances, and its purpose is to drain the water in the supply/condensate piping system when the equipment is stopped, and to completely dry the inside of the supply/condensate piping system. The present invention is intended to provide a rust prevention method for supply/condensate piping systems that can obtain a sufficient rust prevention effect, and an apparatus for carrying out this method. The present invention will be explained below based on one embodiment.

First, the apparatus of the present invention will be explained according to an embodiment shown in FIG. 1 in the figure is a boiling water type nuclear reactor, and the steam generated in this reactor 1 is passed through a main steam pipe 2 to a turbine 3.
It is configured to drive the turbine 3 and the generator 4 connected to the turbine 3.
The steam that has driven this turpin 3 is sent to a condenser 5 and condensed into condensed water. The condensate stored in the condenser 5 is configured to be sent to the nuclear reactor 1 via a series of feed/condensate piping systems 6. This feed/condensate piping system 6 includes a condensate pump 7, an air extractor 8, a gland steam condenser 9, a condensate desalination device 10, a condensate boost pump 11, which are arranged sequentially from the water tank 5 side. A group of feedwater heaters 12..., reactor feedwater pump 1
3. Feed water heater 14 and piping 15 connecting these...
It is composed of... Further, the water level of the condenser 5 is controlled by a condensate storage tank 16 and control valves 17 and 18. At the top of this supply/condensate piping system 6, there is a steam injection valve 19, respectively.
... are connected, and each has a drain valve 20 at the bottom.
...is connected. In addition, the above-mentioned supply/condensate piping system 6
The top of the above means the highest part of the upwardly convex part of the series of flow channels made up of the above equipment and piping, and the bottom means the downwardly convex part of the above flow channels. This means the lowest point of the bent part. The steam injection valves 19 are each connected to a steam supply mechanism 22 via a steam source valve 21. This steam supply mechanism 22 is configured to inject high-temperature, high-pressure steam into the supply/condensate piping system 6 from the top via the steam source valve 21 and the steam injection valve 19 . Further, the drain valves 20 are each connected to a waste water storage tank 23 provided below. A drain pipe 24 is connected to the bottom of this waste water storage tank 23, and this drain pipe 24 is connected to the condenser 5. A drain valve 25 is provided in the middle of the drain pipe 24, and an orifice 26 is provided near the connection portion of the drain pipe 24 with the condenser 5. Further, the wastewater storage tank 23 is provided with a water level detection mechanism 27 that detects the water level inside the tank, and when the water level in the wastewater storage tank 23 falls below a predetermined water level, a signal to that effect is generated. It is configured as follows.
Next, a method of drying the inside of the supply/condensate piping system 6 using the above-mentioned apparatus will be explained.

During operation of the equipment, the above steam injection valve 19...
, drain valve 20, steam source valve 21, and drain source valve 25 are kept closed. Then, when the equipment is stopped, the steam source valve 21, the steam injection valve 19, etc., before the supply/condensate piping system 6 has cooled down.
- is opened to inject high-temperature, high-pressure steam from the top of the steam supply mechanism 22 into the supply/condensate piping system 6 and open the drain valves 20 and 25. Then, due to the pressure and gravity of the injected steam, the water in the supply/condensate piping system 6 is directly sent to the condenser 5 via the waste water storage tank 23 and the drain pipe 24, 5
stored within. In this case, the water in the supply/condensate piping system 6 is discharged by the pressure of the steam, so drainage is completed in a short time, and the supply/condensate piping system 6 is heated by the injected steam. Therefore, even when drainage is completed, the supply/condensate piping system 6 remains at a high temperature. When the drainage is completed, the steam source valve 21 is closed, and the supply/condensate piping system 6 is evacuated using the negative pressure in the condenser 5. Therefore, the supply/condensate piping system 6 is in a high temperature state and its interior is evacuated, so that the water remaining in the supply/condensate piping system 6 is reliably evaporated and the supply/condensate water is The inside of the piping system 6 is completely dried.
Furthermore, when draining the water in the supply/condensate piping system 6, the drained water is temporarily stored in the wastewater storage tank 23, so when the drainage is finished, the water level in the wastewater storage tank 23 decreases. By detecting this drop in water level using the water level detection mechanism 27, it is possible to detect that drainage has ended. In addition, an orifice 2 is provided near the connection part of the drain pipe 24 with the condenser 5.
6 is provided, when the waste water is flowing through this orifice 26, a large pressure difference is generated before and after this orifice 26, and during the drainage, the negative pressure of the condenser 5 is caused to flow through the drain pipe 6 and This prevents water from acting on the supply/condensate piping system 6 and causing the water therein to boil. and,
The water stored in the condenser 5 may be treated with a waste treatment device (not shown), or treated with a condensate desalination device 10 and stored in a condensate storage tank 16 for reuse. It's okay. Note that the method and apparatus of the present invention are not necessarily limited to the above-mentioned embodiment, and for example, the method of the present invention does not necessarily need to be carried out using the apparatus as in the above-mentioned embodiment. Furthermore, the detailed configuration of the device is not necessarily limited to the above.

As mentioned above, the method of the present invention involves injecting high-temperature, high-pressure steam from the top of the supply/condensate piping system, and using the pressure of this steam to quickly discharge the water in the supply/condensate piping system, and at the same time discharging the water in the supply/condensate piping system. This heats the supply and condensate piping system.

Therefore, even when drainage is finished, the supply and condensate piping system remains in a high temperature state, and the remaining moisture is reliably evaporated and the supply and condensate piping system is completely dried, ensuring a reliable rust prevention effect. It is something that can be demonstrated. In addition, the device of the present invention is provided with a steam injection valve at the top of the supply/condensate piping system, and steam is injected from the steam supply mechanism through the steam injection valve, and at the bottom of the supply/condensate piping system, drainage is provided. A valve is provided, and the drain valve is communicated with the condenser through a waste water storage tank, and the waste water storage tank is provided with a water level detection mechanism for detecting a drop in the water level inside the tank. Therefore, when drainage is finished, the water level in the wastewater storage tank drops, and by detecting this drop in water level using the water level detection mechanism, it is possible to detect the end of drainage, which has great effects, such as making work easier. It is. Although the present invention has been described above using nuclear power generation equipment as an example, the present invention is not limited thereto, and is of course also effective in rust prevention of feed/condensate piping systems of thermal power generation equipment and the like.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional device, and FIG. 2 is a system diagram of an embodiment of the device of the present invention. 1...Nuclear reactor, 2...Main steam pipe, 3.
...Turbi. 5...Condenser, 6...
...Supply/condensate piping system, 16...Condensate storage tank, 19...Steam injection valve, 20...Drain valve, 22...Steam Supply mechanism, 23...
Drainage storage tank, 27...Water level detection mechanism.

Claims (1)

[Claims] 1. High-temperature, high-pressure steam is injected from the top of the supply/condensate piping system when the equipment is stopped, and water in the supply/condensate piping system is drained by the pressure of the injected steam. A rust prevention method for supply and condensate piping systems that discharges water from the bottom and sends it to the condenser. 2. A steam injection valve installed at the top of the supply/condensate piping system,
The steam supply mechanism connected to this steam injection valve and the
A drain valve provided at the bottom of the condensate piping system and communicating with the condenser, a wastewater storage tank provided between the drain valve and the condenser to store a predetermined amount of wastewater, and a wastewater storage tank inside the wastewater storage tank. A rust prevention device for a supply/condensate piping system, characterized in that it is equipped with a water level detection mechanism that detects the water level of the water supply/condensate piping system.