JPS6235033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a condensate system for a nuclear power plant, and in particular, it circulates condensate to reduce the occurrence of rust when the plant is stopped, and it also enables the plant to reuse high-purity waste in a short time. This invention relates to a condensate system suitable for recovering water.

First, the prior art will be explained with reference to FIGS. 1 and 2. The steam and condensate water supply system in a nuclear power plant is configured as shown in Figure 1. During plant operation, steam generated in the nuclear reactor 1 expands in the turbine 2 and does work, and then is transferred to the condenser 3. It is cooled and becomes condensate. This condensate is sucked out by a condensate pump 4, introduced into a condensate purification device 6 via a condensate pipe 5, where impurities are removed, and then pressurized by a condensate boost pump 7, and then fed to a feed water heater. 8, the water supply pump 9 increases the pressure, and then the water supply pipe 1
A closed circuit is formed which returns to the nuclear reactor 1 via 0.

In this closed circuit, when the flow rate is unbalanced and the water level in the condenser 3 reaches a high level, the valve 40 is opened and condensate is discharged to the condensate storage tank 12 via the spillover pipe 11.

In addition, the shaft seal of the water supply pump 9 is of a water seal type in the case of 800 MW class or higher, and seal water is supplied to the water supply pump 9 via a water seal supply pipe 13 branched from the discharge pipe of the condensate boost pump 7. The sealed water is collected into a condensate recovery tank 15 via a sealed water return pipe 14. The condensate recovery tank 15 collects some drain water in addition to this sealed water return water. The recovered condensate is pressurized by the recovery pump 16, and then sent to the condensate recovery tank water level adjustment valve 34 and the condensate recovery pump discharge pipe 1.
7 and is recovered to the condenser 3.

During normal operation, this route is used; however, during plant shutdowns, especially during long-term shutdowns such as periodic inspections, in order to reduce corrosion products, the condensate and water supply systems are circulated at low flow rates. Since it has been confirmed through operational experiments that storage operation is effective, low flow rate operation is performed on a limited route.Next, we will explain this circulation storage operation route when the plant is stopped.

When the plant is stopped, the condensate in the condenser 3 is pumped by operating only one condensate pump 4, which is two in normal operation, and one additional condensate boost pump 7, in order to save power within the plant. Alternatively, the condensate boost pump 7 is stopped and the bypass pipe 18 is passed through, and then the condensate is passed through the feed water pump bypass pipe 19 and the condensate feed water recirculation pipe 20 branched from the water supply pipe 10 to the condenser. Return to 3.

However, the shaft power of the condensate pump 4 during circulation storage operation during plant shutdown is large, approximately 1500 KW per unit in the case of a 1000 MW class plant, and in the closed circuit described above, this is transferred to the condensate system as mechanical loss. As the condensate circulates repeatedly, the temperature of the condensate rises, and the evaporated steam of the condensate flows back to the turbine 2 through the condenser 3, causing damage to the turbine 2 itself and periodic turbine inspection work. affect.

Therefore, in order to prevent the temperature of this condensate from rising, conventionally,
Usually, two or three circulating water pumps 21 are operated to send cooling seawater to the condenser 3. However, the internal power of this circulating water pump 21 is also large, about 3000 KW in the case of a 1000 MW class plant.

As described above, in the conventional technology, at least one condensate pump 4 and one circulating water pump 21 must be operated for about 3 months for periodic inspection for circulation storage operation, which reduces the operating cost. is 1
It amounts to more than 100 million yen.

Next, a conventional technique for draining equipment when the plant is stopped will be explained with reference to FIG. Among building drains, drains from pipes and equipment that contain reactor water, condensate, compressed water for water supply and exhaust gas systems, etc. are generally high-purity (low conductivity) waste liquids and are called radioactive equipment drains.

The body drain of the feed water heater 7, the drain from the condensate pipe 5, the water supply pipe 10, and other equipment drains are drained into the equipment drain sump via each equipment drain port 23 by sequentially opening the equipment drain valves 22. 24, the equipment drain pump 25, the waste liquid collection tank, the waste liquid collection pump 27, and then the waste liquid filter 28, where it is over-treated and then desalted in the waste liquid demineralizer 29, after which it is transferred to the waste liquid sample tank 30. , and is collected by the waste liquid sample pump 31 into the condensate storage tank 12 as plant make-up water.

As a means of reducing the load required for waste treatment in such equipment drain processing equipment as much as possible, the drains in the feed water heater 8, the condensate pipe 5, the water supply pipe 10, etc., which have relatively high purity among the equipment drains, are used as equipment drain samples. 24, it is collected in a condensate recovery tank 15, and is collected in a condensate storage tank 12 via a recovery pump 16, a recovery pump discharge pipe 17, a condenser 3, a condensate purification device 6, and a spillover pipe 11. There are also plants. However, in this case as well, since the condensate pump 4 is operated, in order to ensure stable operation of the condensate pump 4, before introducing the comparatively high-purity condensate into the condenser 3, The condensate drain must be collected in advance into the device drain sump 24 in the same way as other device drains, and the condensate pump 4 must be stopped at that time. However, the amount of condensate held by the condenser 3 itself accounts for about half of the amount of condensate other than the amount collected in the condensate recovery tank 15, which places a large load on the equipment drain processing equipment. .

On the other hand, the processing capacity of the equipment drain processing equipment is generally only a few tenths of the amount of drain required when the plant is stopped. For this reason, at present, the number of opening operations of the device drain valve 22 is limited, and draining is performed in several tens of times. For this reason, securing a large number of workers for this work and requiring several weeks to remove the drain become a major problem when the plant is shut down.

An object of the present invention is to solve the problems of the prior art described above, that is, to provide a condensate system configured to reduce the internal power during circulation storage operation and reduce the equipment drain processing load. .

To achieve this objective, the condensate system of the present invention includes a line having a valve connecting the condenser and the condensate recovery tank, and a line branching from the condensate recovery pump discharge pipe to the inlet of the condensate purification device. A line having a valve connected to the water pipe is provided.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. In FIG. 3, 32 and 33 are pipes added according to the present invention to the conventional condensate system shown in FIG. Water appliance drain pipe, piping 3
3 is a condensate communication pipe branched from the condensate recovery pump discharge pipe 17 and connected to the condensate pipe 5 between the condensate pump 4 and the condensate purification device 6; 41 and 36 are these pipes 3;
This is the valve installed at 2 and 33. Of these, valve 36
As shown in FIG. 4, the output of the level transmitter 38 that detects the liquid level of the condensate recovery tank 15 is input, and the opening degree is adjusted by the level regulator 39 to adjust the liquid level of the condensate recovery tank 15. It is operated as a water level control valve to adjust the level. 37 is a level switch for controlling the condensate recovery pump 16, 4
Reference numerals 2 and 43 designate a level transmitter and a level adjuster for a water level adjustment valve 34 that adjusts the water level of the condensate recovery tank 15 during normal operation.

In this configuration, the flow of condensate during circulation storage operation will first be explained. During circulation storage operation, the water level adjustment valve 34, the valve 40 provided on the spillover pipe 11, the valve 44 of the water seal supply pipe 13, and the drain valve 22 of the condenser 3 are closed, while the valve 36 provided according to the present invention is closed. , 41, valve 35 of condensate boost pump bypass pipe 18, water supply pump bypass valve 4
5 and the valve 46 of the condensate feedwater recirculation pipe 20 are opened, and the condensate recovery pump 16 is operated to circulate the condensate. Therefore, the drain in the condenser 3 at this time is recovered to the condensate recovery tank 15 via the condensate drain pipe 32 provided according to the present invention. The recovered condensate is sucked out by the condensate recovery pump 16 and introduced into the condensate purification device 6 via the condensate communication pipe 33 provided according to the present invention, and the condensate purified here is used to increase the condensate pressure. It returns to the condenser 3 via the pump bypass pipe 18, the feedwater heater 8, the feedwater pump bypass pipe 19, and the condensate feedwater recirculation pipe 20. In this case, the liquid level in the condensate recovery tank 15 is determined by the level transmitter 38.
is detected and maintained at a set level by adjusting the opening degree of the valve 36 with the level regulator 39.

During this circulation storage operation, there is no need to seal the water supply pump 9, so the capacity of the condensate recovery pump 16 remains the same as the capacity calculated from the required amount during normal operation (sealed water return, etc.), and the capacity during circulation remains the same. will also be adequately secured. The capacity of this condensate recovery pump 16 is
In the case of a 1000 MW class plant, it is approximately 100 KW. With this level of heat input into the condensate water due to mechanical loss from the pump, heat is dissipated by heat dissipation from equipment and piping in the closed circulation storage circuit, and the above-mentioned condensate A backflow of evaporated steam from the water container 3 to the turbine 2 side does not occur.

Therefore, there is no need to operate the circulating water pump 21 either. Furthermore, all of the condensate pump 4 and condensate boost pump 6 can be stopped.

Next, equipment drain recovery from the condenser 3 will be explained. When recovering the drain inside the condenser, which was a problem in the prior art, the drain valve 22 of the condenser,
The water level adjustment valve 34 and the valve 35 of the condensate boost pump bypass pipe 18 that are operated during normal operation are closed, and the valve 41 of the condenser drain pipe 32 and the valve 3 of the condensate communication pipe 33 are closed.
6. Open the valve 40 of the spillover pipe 11 and collect the condensate while operating the condensate recovery pump 16. In this case, the drain in the condenser 3 enters the condensate recovery tank 15 via the condenser drain pipe 32, and then passes through the condensate recovery pump discharge pipe 17 and the condensate communication pipe 33 to the condensate purification device. After being purified, the water is collected in a condensate storage tank 12 via a spillover pipe 11.

In this case, a mechanism for switching the conventional condenser drain to the drain port 23 is also provided in consideration of the case where trouble should occur in this recovery line. Further, the method of collecting and purifying the drain around the feed water heater 8, the feed water, and the condensate into the condensate recovery tank 15 is followed and used in combination.

As mentioned above, the water level of the condensate recovery tank 15 is adjusted by the water level adjustment valve 34 during normal operation.
The water level adjustment valve 36 is used during the condenser drain collection and circulation operation, but in order to improve the reliability of control and the difference in capacity during each operation, level transmitters are installed separately as shown in the figure to adjust the operation timing. Therefore, the water level adjustment valve on one side is forced to close. Furthermore, when the condenser drain is completely drained during condenser drain recovery, the level switch 37 is activated to automatically trip the condensate recovery pump 16.

In this embodiment, condenser drain is collected in the conventionally installed condensate recovery tank 15, but a dedicated condensate recovery tank for condenser drain recovery is provided, and a separate Water may be supplied to the inlet condensate pipe 5 of the condensate purification device 6 by a dedicated pump.

As described above, in the present invention, a pipe having a valve that connects a condenser and a condensate recovery tank, and a valve that connects a condensate recovery pump discharge pipe and a condensate pipe on the inlet side of a condensate purification device are provided. By providing piping with this system, it is no longer necessary to operate condensate pumps and circulating water pumps that require large amounts of power in the plant during circulation storage operations during long-term plant shutdowns, thereby significantly reducing operating costs. Specifically, one periodic inspection can reduce operating costs by approximately 200 to 300 million yen, and over the life of the plant, the operating costs can be reduced by several billion yen or more.

In addition, since the load on the equipment drain processing equipment is reduced, drain can be removed in a short time when the plant is stopped, which greatly reduces the number of workers and the number of days required. It also plays a major role in shrinkage. In addition, the trouble of coordinating the processing timing with other equipment drains can be saved.

[Brief explanation of the drawing]

Fig. 1 is a schematic system diagram of a steam and condensate water supply system in a conventional nuclear power plant, Fig. 2 is a schematic system diagram of a conventional radioactive equipment drain facility, and Fig. 3 is a schematic diagram of a steam and condensate water supply system in a conventional nuclear power plant. A schematic system diagram of the condensate water supply system, and FIG. 4 is a detailed system diagram of its main parts. 3... Condenser, 4... Condensate pump, 6... Condensate purification device, 11... Spillover pipe, 12... Condensate storage tank, 15... Condensate recovery tank, 16... Condensate recovery pump, 17... Condensate recovery Pump discharge pipe, 32...Condenser drain pipe, 33...Condensate communication pipe.

Claims (1)

[Claims] 1. A condenser that condenses steam from a steam turbine, a condensate pump that sucks out condensate from the condenser, and a condensate purification device that filters and desalinates the condensate sucked out by the condensate pump. , a condensate recovery tank that collects return water from the shaft seal of the feedwater pump that supplies water to the reactor, a condensate recovery pump that sucks out condensate from the condensate recovery tank, and sends it to the condenser. In a condensate system of a nuclear power plant equipped with a water recovery pump discharge pipe, a condenser drain pipe connecting the condenser and a condensate recovery tank and having a valve is provided, and the condensate recovery pump discharge pipe 1. A condensate system comprising a condensate communication pipe branched from a pipe, connected to a condensate pipe connecting the condensate pump and the condensate purification device, and having a valve.