JP3888894B2 - Condensate treatment system and condensate treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a condensate treatment system and a condensate treatment method in a nuclear power plant or a thermal power plant, and in particular, when the packed ion exchange resin of any condensate demineralization tower is replaced, Condensate treatment system and condensate so that normal operation can be efficiently started with the minimum amount of blowout outside the condensate system without any trouble when entering normal condensate treatment operation after purification treatment It relates to the processing method.
[0002]
[Prior art]
In nuclear power plants and thermal power plants, a plurality of condensate demineralization towers are usually arranged in parallel in the condensate circulation system so that the condensate from the condenser can be desalted. Each condensate demineralization tower is filled with an ion exchange resin. In general, an ion exchange resin that has been used for sampling and has reached a predetermined life is transferred to a regeneration tower for regeneration, and is regenerated here. . The regenerated ion exchange resin stands by in a storage tank and is transferred into a condensate demineralizer as necessary. For regenerated ion exchange resin that has been transported into the desalting tower, it is necessary to remove trace amounts of impurities, dissolved oxygen, etc. remaining after regeneration before sampling (ie before normal operation). A purification process is performed. In this purification process, there are usually an extra-blowing process in which condensate is passed through a condensate demineralizer to wash out trace impurities in the ion exchange resin, and the passed condensate is blown out of the system. A recovery blow process in which the condensate from the water demineralizer is returned to the condenser, the dissolved oxygen is removed by the deaerator in the condenser, and the condensate from the condenser is circulated in the normal condensate circulation system. A circulation process is performed in this order, in which the condensate is circulated through a condensate demineralizer equipped with a plurality of demineralization towers to increase the purity of the condensate.
[0003]
On the other hand, in recent years, regarding the operation of the condensate demineralizer with a plurality of condensate demineralizers as described above, the condensate demineralizer is used for emergencies such as when seawater leaks into the condenser. Although the number of towers should be secured, since the purity of condensate is maintained sufficiently high during normal processing, it is not necessary to use the entire condensate demineralization tower. Plant operation to bypass the condensate demineralizer has been started. In addition, when operating at a high pH, the operation is generally to bypass the condensate without passing through the condensate.
[0004]
[Problems to be solved by the invention]
However, when the conventional purification process as described above is performed in a plant that is premised on the operation of bypassing the condensate demineralizer for a part or all of the condensate as described above, the following problems arise.
[0005]
That is, in a plant that performs bypass operation etc., the condensate demineralizer with the exchanged packed ion exchange resin is first passed through the condensate to wash and remove impurities, and the condensate used for the system is used. When the outside blows but continues into the recovery blow process, the condensate that does not pass through the condensate demineralization tower is sent to the subsequent steam generation means (steam generator or boiler), etc. become. The condensate sent to the steam generating means, etc. is recovered from the condensate demineralization tower to the condenser, but contains a small amount of impurities and may not satisfy the predetermined purity. If such condensate is sent to the steam generating means or the like without passing through the condensate demineralization tower, there is a risk that the steam generating means or the like may suffer from problems such as corrosion or a decrease in heat transfer efficiency. In order to prevent the occurrence of such inconvenience, at the stage of entering the recovery blow process, the recovery blow water at the outlet of the desalting tower is required to have a water quality equivalent to that at the time of in-service (normal operation).
[0006]
In order to satisfy this requirement, for example, if the total amount of demineralizer outlet water in the recovery blow process is discharged out of the system as it is, a remarkably large amount of washing water will be discharged out of the system and replenishment to the condensate system. Problems such as insufficient capacity and water quality deterioration due to an increase in the ratio of makeup water in condensate occur.
[0007]
Furthermore, in the conventional purification process, a condensate from the desalting tower is finally circulated to increase the purity of the condensate. In this circulation step, as shown in FIG. 6, treated water from a specific desalting tower 101 is returned to the condensate inlet main pipe 103 via the circulation pump 102 and the circulation water channel 104.
[0008]
Thus, in a plant premised on the operation of bypassing the condensate demineralizer for a part or all of the condensate, the purification process for performing the conventional external blow process, the recovery blow process, and the circulation process in this order is If it is applied as it is, purification treatment prior to normal water sampling will be insufficient, or an extremely large amount of extra blow water will be required.
[0009]
Therefore, an object of the present invention is to improve a purification method for a specific condensate demineralization tower that is performed before normal operation, particularly for a plant that is premised on an operation that bypasses the condensate demineralizer for part or all of the condensate. And a condensate treatment system that can easily raise the purity of the condensate water circulated in the system to a target level that does not cause problems while minimizing the amount of condensate discharged outside the system. It is to provide a condensate treatment method.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, a condensate treatment system according to the present invention includes a condensate demineralizer having a plurality of condensate demineralization towers for demineralizing condensate from a condenser, and the condensate. In the condensate treatment system having a bypass passage capable of bypassing a part or all of the condensate from the condenser with respect to the demineralizer, each condensate demineralizer from the condensate demineralizer is The outlet water is not returned to the condensate inlet main pipe but is circulated only in the condensate demineralization tower, and a separate circulation path that is separable from other condensate demineralization towers is provided.
[0011]
The condensate treatment method according to the present invention includes, during normal operation, a condensate demineralization passage for passing the condensate from the condenser to a condensate demineralizer having a plurality of condensate demineralization towers arranged in parallel. A part or all of the condensate from the condenser is selectively passed to the bypass path that can bypass the water to the water desalination unit, and the ion exchange resin filled in one of the condensate demineralization towers is replaced. The condensate demineralization tower is blown out of the system, and the outlet water from the condensate demineralization tower is not returned to the condensate inlet main pipe. An individual circulation step for individually circulating the condensate only for the demineralization tower, a recovery blow step for returning the condensate from the condensate demineralization tower to the condenser and circulating it in the system using the bypass path in this order. After performing, it consists of a method characterized by starting normal operation.
[0012]
In the condensate treatment system and the condensate treatment method according to the present invention, the condensate demineralization tower whose packed ion exchange resin has been exchanged is first passed through the condensate demineralization tower by passing the condensate. The external blow process for blowing the condensate out of the system is the same as the conventional method, but following this out-of-system blow process, an individual circulation process is performed to circulate the condensate separately only for the condensate demineralizer. Is done. That is, the outlet water from the condensate demineralization tower is not returned to the condensate inlet main pipe, but is circulated only for the condensate demineralization tower. In such individual circulation, the condensate containing a trace amount of impurities is not likely to flow into the condensate circulation system via other demineralization towers, condensers, or even bypass paths. Undesirable impurities will be removed to a sufficient level only in the desalting tower system. A recovery blow process is performed after this individual circulation process. At the time of this recovery blow process, the specific desalting tower has already been purified to a level that does not cause a problem by the individual circulation process. Even if the water is sent to the steam generating means at the subsequent stage through the bypass (that is, not through the demineralizer) after the deaeration treatment in the condenser, no problem occurs. Therefore, in the recovery blow process, the condensed oxygen is circulated in the system, so that the dissolved oxygen is satisfactorily removed without causing other problems by the deaerator in the condenser. After the predetermined recovery blow process is completed, the water quality is suitable for normal operation (normal water sampling), so normal operation, particularly bypass operation can be started as it is.
[0013]
In the present invention, a circulation step similar to the conventional one may be performed as necessary after the recovery blow step. In addition, during high pH operation, the concentration of ammonia in the condensate is high and it is difficult to perform condensate treatment with a condensate demineralizer, so that the entire amount of normal condensate is bypassed. Therefore, the presence or absence of the individual circulation process according to the present invention has a great influence on the amount of water used, the water quality when it is sent to the steam generating means, and the like.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a condensate treatment system according to an embodiment of the present invention, and particularly shows a system in which the present invention is applied to a pressurized water nuclear power plant. In FIG. 1, a steam generator 1 performs heat exchange with a primary system of a pressurized water nuclear power plant to generate steam. The high-pressure turbine 2 is driven by the generated steam, and the used steam is sent to the condenser 4 through the moisture separation heater 3 and cooled.
[0015]
The condensate from the condenser 4 is sent to the steam generator 1 through the condensate pump 5 and the feed water pump 16, but in this embodiment, during normal operation, the bypass valve 6 is opened and the condensate demineralizer inlet. The valve (device inlet valve) 7 is closed, and the condensate demineralizer 10 having a plurality of condensate demineralizers 9 arranged in parallel is bypassed. The condensate passing through the bypass passage 11 passes through a condensate booster pump 13, a low pressure feed water heater 14, a deaerator 15, a feed water pump 16, and a high pressure feed water heater 17 provided in the condensate reflux passage 12. 1 is supplied. Alternatively, by opening the apparatus inlet valve 7 and the inlet valve 18 and outlet valve 19 of some condensate demineralization towers 9 and closing the inlet valve 18 and outlet valve 19 of some condensate demineralization towers 9. It is also possible to perform a condensate partial treatment in which a part of the condensate is desalted in the condensate demineralization tower 9.
[0016]
Each condensate demineralization tower 9 can be circulated by a circulation pump 23 by opening an outlet valve 21 through the circulation line 20. A common pump is provided for the water desalting tower 9.
[0017]
The outlet water from each condensate demineralization tower 9 circulated by the circulation pump 23 is not returned to the condensate inlet main pipe 24, but an individual circulation path provided for each condensate demineralization tower 9. 25, through individual inlet valves 26, can be circulated individually. Further, an individual system outside blow pipe 22 is connected to the outlet side of the condensate demineralization tower 9, and the individual system outside blow pipe 22 is provided with an individual system outside blow valve 29. The individual external blow pipes 22 are each connected to an external blow pipe 28.
[0018]
A recovery blow line 30 for recovering outlet water is connected to the condenser 4 from each condensate demineralization tower 9, and a recovery blow valve 31 is provided for each condensate demineralization tower 9 individually. ing.
[0019]
The blow-down water supply line 32 of the steam generator 1 is connected to the condenser 4 via a valve 33 in this embodiment, and is connected to the inlet side main pipe of the condensate demineralizer 10 via a valve 34. 24. Further, in the system during the bypass, condensate discharged from the steam generator 1 is passed through a line 32 and a valve 34 to a part or all of the condensate demineralizer and through a condensate outlet main pipe 27. This is done by returning to the condensate reflux path 12.
[0020]
FIG. 2 shows a comparison of the configuration of the individual circulation path 25 with the conventional configuration shown in FIG. That is, in the conventional configuration, the circulation path from each condensate demineralization tower is connected to the condensate inlet mother pipe, but in the present invention, the circulation path is not connected to the condensate inlet mother pipe 24. The individual circulation path 25 of each condensate demineralizer 9 can be formed in a form separated from the condensate demineralizer.
[0021]
In the condensate treatment system shown in FIG. 1, the condensate treatment is performed as shown in FIGS.
First, as shown in FIG. 3, the bypass passage 11 that has been operated until then is shut off by closing the apparatus bypass valve 6, and the apparatus inlet valve 7 and the inlet valve of a specific condensate demineralization tower 9 that has been replaced with resin. 18, the individual outside blow valve 29 is opened, and the outside blow process is performed on the condensate demineralization tower 9. In this out-of-system blow process, most of the mixed impurities are washed and discharged out of the system together with blow water.
[0022]
Next, as shown in FIG. 4, the inlet valve 18 and the individual external blow valve 29 of the condensate demineralization tower 9 are closed, the outlet valve 21 and the individual inlet valve 26 are opened, The outlet water of the water desalting tower 9 is individually circulated through the individual circulation path 25 in a state of being completely separated from other condensate demineralization towers. By this individual circulation step, sufficient washing is performed in the specific condensate demineralization tower 9 and the ion exchange resin filled therein, and the content of impurities is reduced to a level where there is no problem.
[0023]
Then, as shown in FIG. 5, the individual circulation path 25 is closed, the inlet valve 18 and the recovery blow valve 31 of the condensate demineralization tower 9 are opened, and the apparatus bypass valve 6 of the bypass path 11 is opened, so that the recovery blow Water is returned to the condenser 4, and dissolved oxygen is removed by a deaeration device in the condenser 4. This recovery blow process is performed through a line that passes the condensate through the bypass passage 11 to the normal reflux passage 12, and the dissolved oxygen is reduced to a sufficiently low level by passing through the condenser 4.
[0024]
The normal operation may be started after the recovery blow process. That is, it is possible to perform an operation of bypassing the condensate demineralizer 10 with a part or all of the condensate using water flow to the bypass passage 11. However, after the recovery blow step, if necessary, circulation processing in the same manner as in the prior art, that is, the outlet water of the condensate demineralization tower 9 is returned to the condensate inlet main pipe 24 and another condensate demineralization tower You may perform the process which accept | permits the circulation to 9.
[0025]
Thus, in the condensate treatment method according to this embodiment, after the extra blow process and before the recovery blow process, the specific condensate demineralization tower 9 is completely different from the other condensate demineralization tower 9. Since the individual circulation is performed in a separated form, the content of impurities can be sufficiently reduced to a target level without any problems by this individual circulation step, and the recovery blow step can be entered in that state. Therefore, in the recovery blow process, the possibility of occurrence of problems in the steam generating means due to the inclusion of a small amount of impurities is completely removed. As a result, normal operation after the recovery blow process is smoothly started in a good state.
[0026]
In addition, in the series of processes described above, it is not necessary to discharge the condensate outside the system other than the first out-of-system blow process, and the amount of out-of-system discharge can be reduced. Also, the problem of water quality deterioration due to a large amount of water supply does not occur.
[0027]
Incidentally, as described above, in the conventional method, in order to ensure the water quality before the start of normal operation, assuming that all the water in the system blow process, the recovery blow process, and the conventional circulation process is discharged out of the system, In one plant,
・ Outside system blow: 240 t / h × 10 minutes ・ Recovery blow: 240 t / h × 50 minutes ・ Circulation: 510 t / h × 20 minutes of operation requires a total of 410 t of condensate to be discharged outside the system. Must be replenished with a corresponding amount of water. However, in the condensate treatment method according to the present invention as described above, it is understood that the discharge of the condensate outside the system is only 40 t in the out-of-system blow process, and the discharge amount can be greatly reduced.
[0028]
【The invention's effect】
As described above, according to the condensate treatment system and the condensate treatment method according to the present invention, partial condensate operation and operation of bypassing the condensate demineralizer for part or all of the condensate are performed. In the presupposed plant, an individual circulation process was performed for a specific condensate demineralization tower before the recovery blow process, so that the impurity content could be reduced to a sufficiently low target level before the recovery blow process. It is possible to greatly improve the water level before the start of normal operation by greatly improving the achievement level in the purification treatment. Further, since the condensate can be discharged out of the system only in the first out-of-system blow process, the amount of condensate discharged out of the system can be reduced.
[Brief description of the drawings]
FIG. 1 is an equipment system diagram of a condensate treatment system according to an embodiment of the present invention.
2 is a schematic system diagram of an individual circuit portion in the system of FIG.
3 is an equipment system diagram showing an extra-system blow process in the system of FIG. 1. FIG.
4 is an equipment system diagram showing an individual circulation process in the system of FIG. 1. FIG.
FIG. 5 is an equipment system diagram showing a recovery blow process in the system of FIG. 1;
FIG. 6 is a schematic equipment diagram showing a conventional circulation process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steam generator 2 High pressure turbine 3 Moisture separation heater 4 Condenser 5 Condensate pump 6 Bypass valve 7 Condensate demineralizer inlet valve 9 Condensate demineralizer 10 Condensate demineralizer 11 Bypass path 12 Condensate Reflux passage 13 Condensate booster pump 14 Low pressure feed water heater 15 Deaerator 16 Feed water pump 17 High pressure feed water heater 18 Condensate demineralization tower inlet valve 19 Condensate demineralization tower outlet valve 20 Circulation line 21 Outlet valve 22 Outside individual system Blow pipe 23 Circulation pump 24 Condensate inlet mother pipe 25 Individual circulation path 26 Individual inlet valve 27 Condensate outlet mother pipe 28 Out-of-system blow pipe 29 Out-of-system blow valve 30 Recovery blow line 31 Recovery blow valve 32 Blow-down water supply Line 33, 34 valve

Claims (2)

A condensate demineralizer having a plurality of condensate demineralization towers that demineralize the condensate from the condenser, and a part or all of the condensate from the condenser to the condensate demineralizer in condensate processing system having a bypass water flow by-pass passage, for each condensate demineralizer, for the condensate demineralizer without returning outlet water from該復water demineralizer the condensate inlet header tube A condensate treatment system characterized in that a separate circulation path that circulates only and is separable from other condensate demineralization towers is provided. During normal operation, a condensate demineralization passage for passing the condensate from the condenser to a condensate demineralizer having a plurality of condensate demineralizers arranged side by side, and the condenser demineralizer from the condenser When a part or all of the condensate is selectively passed to a bypass passage that allows bypass water flow, and the ion exchange resin in one of the condensate demineralization towers is replaced, the condensate demineralization is performed. An extra-blow process for blowing the condensate that has passed through the tower out of the system, and condensing the condensate separately only for the condensate demineralization tower without returning the outlet water from the condensate demineralization tower to the condensate inlet main pipe. The normal circulation operation should be started after the individual circulation process to be circulated and the recovery blow process in which the condensate from the condensate demineralizer is returned to the condenser and circulated in the system using the bypass path in this order. Condensate treatment method characterized by.

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