JP2001239262A - Method of operating condensate demineralizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of operating a condensate demineralizer, buy which the demineralizer can be operated at a flow velocity of water (condensate) passing through a demineralization tower in a range exceeding the upper limit of the flow velocity in an existing actual plant. SOLUTION: This operating method comprises passing water (condensate) through a demineralization tower at a linear flow velocity of 150-220 m/h. Alternatively, the operating method comprises using a demineralization tower provided with a flow distribution means placed at a point immediately downstream from an inflow port and a flow straightening means placed downstream from the flow distribution means in the water passage direction and passing water (condensate) through a demineralization tower at a linear flow velocity of 130-220 m/h.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for operating a condensate desalination apparatus provided in a condensate treatment system of a nuclear power plant or a thermal power plant.

[0002]

2. Description of the Related Art In a nuclear power plant or a thermal power plant, a condensate desalination device is provided for purifying condensate from a steam generator. This condensate desalination unit is installed in the condensate system for the purpose of removing iron clad and ionic impurities in the condensate. Desalination towers usually have 4 to
Eight reactors are installed, and the linear flow velocity of the condensate flowing in each desalination tower is usually set in the range of 80 to 124 m / h.

However, in a plant in which a pre-coat type condensate filtration device is installed in series with a condensate demineralization device to pass water, an iron clad load on the condensate demineralization device is reduced by filtration using an upstream filtration device. It has been proposed that the linear flow velocity of the condensate flowing in the condensate demineralization tower can be increased to 130 to 150 m / h because it is almost eliminated and the ion load is reduced (Japanese Patent Publication No. 4-37396). ).

[0004] The flow rate of water through the condensate desalination tower is determined by the fact that the amount of circulation of condensate from the steam generator in each nuclear power plant or thermal power plant is determined to be substantially constant by the initial design. However, it is substantially determined by the number of installed desalination towers in the condensate desalination apparatus, and cannot be arbitrarily changed during operation or according to operation conditions. Therefore, for example,
In the official gazette, the linear flow velocity in the desalination tower is 130 to 150 m / h.
However, passing water at a linear flow rate higher than 150 m / h using the disclosed operating method generally does not reduce the number of desalination towers in the condensate treatment system. It is a system that can not be done as far as possible.

[0005]

It is conventionally known that the treated water of a condensate desalination apparatus contains several kinds of organic impurities. Most of these are impurities eluted from the ion exchange resin filled in the desalting tower, and are generated by the ion exchange resin undergoing oxidative decomposition by dissolved oxygen or an oxidizing agent. Of these, the organic impurities eluted from the cation exchange resin are usually polystyrene sulfonic acids, which have recently become a problem because they are decomposed in a nuclear reactor or a steam generator to generate sulfate ions. Since sulfuric acid causes corrosion of the structural material and generation of scale, it is desirable to reduce sulfuric acid as much as possible, and several reducing methods have been proposed. As a result of the investigation by the present applicant, as shown in FIG. 5, it was found that the polystyrene sulfonic acid concentration (organic SO ₄ concentration) in the treated water can be reduced by increasing the water flow velocity in the desalination tower. Therefore, it was found that it is desirable to increase the flow rate of water as much as possible from the viewpoint of minimizing the amount of sulfuric acid generated.

[0006] However, when the flow rate of water in the desalination tower is increased from 80 to 124 m / h, there is a concern that the performance of removing the iron clad and ionic impurities in the condensate desalination apparatus is reduced. Regarding the iron clad removal rate, it can be ignored because the iron clad load on the desalination tower is almost eliminated by arranging it in series with the condensate filtration device and passing water, but the problem of reduced ionic impurity removal performance still remains. Remains. For this reason, the conventionally proposed flow velocity is, as described above, at most 130 to 150 m.
/ H is the upper limit.

[0007] It has also been found that the following problems occur in the desalination tower when the flow rate of water is increased. For example, as shown in FIG. 6, a distributor 103 is provided immediately after the inlet pipe 102 in the desalination tower 101, and the condensate is dispersed and then flows in the desalination tower 101. Or at a higher linear flow velocity, the flow state in the desalination tower 101 is disturbed to generate a swirling flow.
04 is wound up, the design resin surface 1
It was confirmed that a depression 106 was generated with respect to 05. When the surface of the resin layer is depressed, the effective resin layer height partially decreases, the differential pressure decreases, and condensate flows intensively in that part.
There is a problem that the quality of the treated water collected by the water collecting collector 107 and discharged from the outlet pipe 108 is deteriorated, and the flow-through exchange capacity of the desalination tower 101 is reduced.

[0008] Such problems occur more or less in any type of condensate desalination tower. For example, FIG.
In the desalination tower 111 of a different type shown in FIG.
13 and is supplied to the packed bed of the ion exchange resin 115 after being rectified by the rectifying plate 114. However, since a high flow rate of water is not taken into consideration at the design stage, the rectifying plate 114 Is not optimized, and 1
When passing water at a linear velocity of 30 m / h or more,
Also, as shown in FIG.
Was confirmed to occur. Therefore, as with the desalination tower shown in FIG.
There is a problem that the quality of the treated water discharged from the reactor deteriorates and the flow-through exchange capacity of the desalination tower 111 decreases.

In view of the above problems, the flow rate of water through the desalination tower is 124 m / h in an actual plant,
It did not exceed 0 m / h, and it was difficult to reduce polystyrene sulfonic acid by increasing the flow rate of water.

Therefore, the object of the present invention is, as described above, to be about 124 m / h in an actual plant, and 150 m / h as a value proposed by the preceding application, which has not been actually performed.
It is an object of the present invention to provide a method for operating a condensate desalination apparatus that can operate in a region exceeding the upper limit value of the flow velocity of / h.

[0011]

In order to solve the above-mentioned problems, a method of operating a condensate desalination apparatus according to the present invention is applied to a desalination tower.
The method comprises passing water at a linear flow rate of more than 0 m / h and 220 m / h or less.

[0012] As a more specific embodiment, the method of operating a condensate desalination apparatus according to the present invention includes a desalination tower provided with a dispersing means immediately after an inlet and a rectifying means downstream of the flow direction. Water is passed through the desalination tower at a linear flow rate of 130 to 220 m / h. In this method, it is preferable that the desalination tower has a speed of more than 150 m / h
Water is passed at a linear flow rate of 20 m / h or less.

As the dispersing means, a baffle plate or a distributor can be used. The rectification means may be of any type as long as it has a rectification function. For example, a structure in which one or more perforated plates are provided can be adopted. This rectifying means is preferably provided in a straight body part, particularly in the case of a cylindrical desalination tower, with respect to the dispersing means provided immediately after the inlet. It is also possible to employ a structure which serves both as the dispersing means and the rectifying means, for example, a perforated baffle plate.

In the method for operating a condensate desalination apparatus according to the present invention, it is preferable to operate an ammonia type or an alternative amine type. With such an operation, the flow rate of water can be increased, and even if the flow-through exchange capacity is reduced, the frequency of regenerating the chemical of the charged ion exchange resin can be maintained at a very low frequency.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described together with preferred embodiments with reference to the drawings.
First, the mechanical configuration of the condensate desalination apparatus according to the present invention will be described. FIG. 1 shows one embodiment of a condensate desalination apparatus used in the present invention. In FIG. 1, reference numeral 1 denotes an entire condensate desalination apparatus. In this embodiment, a condensate filtration apparatus 4 having a built-in filter 3 upstream of a condensate system 2 and a condensate desalination tower 5 downstream. (A plurality of towers are juxtaposed, but only one of them is shown.) Are arranged in a series. Condensate flows into the desalination tower 5 from the inlet pipe 6. In the present embodiment, a baffle plate 8 as a dispersing means is disposed at a position immediately after the inlet 7 of the inlet pipe 6. .

The desalination tower 5 has a cylindrical tower configuration, and has upper and lower end plates 9a and 9b and a straight body 10 therebetween. A perforated plate 11 as a rectifying means is provided at or near the most upstream portion of the straight body portion 10. In the present embodiment, two perforated plates 11 are arranged at intervals. The screen 12 is filled with the ion exchange resin 13 in the desalination tower 5. The upper surface is matched with the design resin surface 14, and is filled with the ion exchange resin 13 at a predetermined layer height. An outlet pipe 15 for discharging condensed water after the treatment is connected to the lower end plate portion 9b, and a resin transfer pipe 16 from the screen 12 penetrating through the end plate portion 9b for resin exchange or regeneration. Is hanging.

FIG. 2 shows another embodiment of a condensate desalination apparatus usable in the present invention. In FIG. 2, 2
Reference numeral 1 denotes an entire condensate desalination apparatus. As in the above embodiment, a condensate filtration apparatus 24 having a built-in filter 23 on the upstream side of the condensate system 22 and a condensate desalination tower 25 (a plurality of parallel towers) on the downstream side. Although only one tower is shown in the figure)
Are arranged in a series. Condensate flows into the desalination tower 25 from an inlet pipe 26. In the present embodiment, a distributor 28 as a dispersing means is disposed at a position immediately after the inlet 27 of the inlet pipe 26.

The desalination tower 25 has a cylindrical tower configuration, and includes upper and lower end plate portions 29a and 29b and a straight body portion 30 therebetween.
have. A perforated plate 31 as a rectifying means is provided at or near the most upstream portion of the straight body portion 30. In this embodiment, as in the above-described embodiment, two perforated plates 31 are arranged at intervals. The ion exchange resin 32 is filled in the desalination tower 25, and the upper surface thereof is fitted to the design resin surface 33, and the ion exchange resin 32 is filled at a predetermined layer height. A water collector 34 is provided at a lower part in the desalination tower 25, and the treated water is discharged through an outlet pipe 35 connected to the water collector 34.

The operating method according to the present invention is carried out as follows using the condensate desalination apparatuses 1 and 21 as described above. In the above-mentioned Japanese Patent Publication No. 4-37396, it is described that when the flow rate of water through the desalting tower is set to 150 m / h or more, the ion exchange performance rapidly decreases. But actually,
As shown in FIG. 3, when a confirmation test was performed using a new resin or a used resin of a BWR type power plant (boiling water nuclear power plant), the flow-through exchange capacity was reduced when the flow rate was increased. We found that there was almost no change in water quality (evaluated by electrical conductivity). The conditions of the BWR actual machine use test shown in the figure are as follows. Height of resin layer in desalting tower: 1000 mm Ion exchange resin ratio used: cation exchange resin / anion exchange resin = 2/1 Inlet salt concentration: 2 mg / L-NaCl Water passing end point: Guaranteed water quality of treated water conductivity: 0 .1μS / cm

That is, in contrast to the known range including Japanese Patent Publication No. 4-37396 (the maximum flow rate of 150 m / h), even when the flow rate is more than 150 m / h and 220 m / h or less, it is sufficient. It was found that excellent treated water quality was obtained, and the decrease in the once-through exchange capacity could be suppressed to 80% at a flow rate of 220 m / h.
That is, it was found that the quality of the treated water does not deteriorate even if the flow rate of water is increased unless a resin whose ion exchange performance is significantly reduced is used.

Regarding the quality of the treated water, FIG.
As shown in the figure, it has been found that a high flow rate can be maintained in a test at a thermal power plant (4 years actual resin) and at a PWR power plant (pressurized water nuclear power plant) (4 years actual resin). .

Further, as shown in FIG. 4, it has been found in a test on the actual machine in the above-mentioned BWR that the through-flow exchange capacity is further reduced when the resin surface is dented when the flow rate is increased. As a result, it can be understood that a reduction in the once-through exchange capacity can be suppressed by taking measures to prevent such depressions in the desalination tower, and the characteristics of the solid line shown in FIG. 2 shows characteristics when the structure shown in FIG.

Further, as shown in FIG.
It has been found that the concentration of O ₄ can be reduced as the flow rate of water is increased.

Based on the above-mentioned findings, the current actual water flow velocity is about 124 m / h, but it is more than 130 m / h.
It is possible to obtain a prospect that operation at a water flow rate of 0 m / h or less is possible, and it is possible to obtain a prospect that operation at a water flow rate of more than 150 m / h and 220 m / h or less is obtained. It was completed.

In particular, as shown in FIG.
Even if a resin whose ion exchange performance has been reduced after use for a year is used, since the flow rate of 220 m / h is satisfied with the guaranteed value of the treated water quality of 0.1 μS / cm, the upper limit of the flow rate is set to 220 m / h. Can be set. The flow-through exchange capacity decreases as the flow rate increases, but the rate of decrease at a flow rate of 220 m / h is about 20%. Therefore, it can be easily dealt with by increasing the effective resin amount. Therefore, based on these findings, the water flow velocity is 130 to 220 m / h,
Operation in the range of more than 50 m / h and 220 m / h or less is enabled.

In order to prevent disturbance of the flow state caused when the flow velocity is increased, the desalination tower is made cylindrical, a baffle plate or distributor is provided at the inlet as a rectifying mechanism, and one or more sheets are provided at the straight body. By installing the rectifying plate of the above, it becomes possible to operate without generating a depression on the resin surface in the range of the flow velocity of 130 to 220 m / h, while suppressing a decrease in the flow-through exchange capacity, and
High flow rate operation is possible while maintaining the quality of the treated water.

In the PWR power station and the thermal power station, the condensate desalination apparatus is operated in an ammonia type or an alternative amine type (such as an ethanolamine type), so that the flow-through flow rate is increased to increase the flow-through exchange capacity. Even if it decreases, it is possible to keep the frequency of chemical regeneration low.

That is, as a method for desalination of condensate,
H-type operation of performing condensate treatment using an H-type cation exchange resin and ammonia-type operation or alternative amine-type operation of performing condensate treatment using an NH ₄ type cation exchange resin are known. In recent thermal power plants and the like, desalination treatment is mostly performed in an ammonia type operation or an alternative amine type operation. For example, in ammonia-type operation, H-type operation is usually performed only at the start of water flow, and during condensate, the generation of eluting ions and cladding components (particularly iron oxide) from the inner surfaces of pipes, equipment, and valves is suppressed. cation exchange resin by NH ₄ ⁺ ions in the condensate water with ammonia for pH adjustment, which is added for the purpose of is converted to NH ₄ form the H-type, NH ₄ from the time the cation exchange resin is saturated by all NH ₄ ⁺ ions ⁺ Ions are passed through, and only impurity ions such as Na ⁺ ions are removed. As a result, the number of water passages in the ammonia type operation is greatly extended compared to the number of water passages in the H type operation,
Accordingly, the regeneration frequency of the ion exchange resin is lower than that of the H-type operation. The same effect is obtained in the alternative amine type operation.

In this ammonia-type operation, ammonia is added to the condensed water as described above, and its pH is adjusted to 9.3.
Such a water supply method, which is raised to about 9.5, is usually referred to as a volatile substance treatment method (AVT).

However, recently, in the ammonia type operation as described above, the quality of the condensed water has been improved along with the technical progress of the regenerating method such as the adoption of the separation and regenerating method. One of the salt towers was H-type water with good treated water quality),
Further, in conjunction with the recent technological progress of the condensate desalination apparatus, the frequency of regeneration of the ion exchange resin has been further reduced. In particular, in the current state-of-the-art thermal power plants, the frequency of regeneration in the regeneration system of condensate and desalination equipment in ammonia type operation has been reduced to once or less per month for each desalination tower.

Therefore, by performing the ammonia type operation or the alternative amine type operation as described above, even if the flow rate of water increases and the once-through exchange capacity decreases, the frequency of chemical regeneration is substantially kept extremely low. , Driving can be continued.

In the present invention, the flow rate of water can be increased to within the target range specified in the present invention, as described above, mainly by optimizing the number of desalination towers.

[0033]

As described above, according to the method for operating the condensate desalination apparatus of the present invention, the flow rate of water is set to be more than 150 m / h and not more than 220 m / h, or 130 to 220 m / h. , Organic SO eluted from ion exchange resin
_{4 The} concentration can be greatly reduced, and the quality of treated water can be greatly improved. In addition, since the water is passed through the condensate desalination device at a high flow rate, the number of desalination towers can be reduced, and the equipment can be downsized.

Further, by using a baffle plate or distributor provided at the inlet of the desalination tower as a rectification mechanism and a desalination tower having one or more rectification plates provided at the straight body portion, the flow rate of water can be reduced to 130. Up to 220 m / h, the turbulence of the resin layer of the desalting tower can be prevented, and a high flow rate of water can be achieved while suppressing a decrease in the quality of treated water and a flow-through exchange capacity.

Further, in the PWR power plant and the thermal power plant, the condensate demineralizer is operated in an ammonia type or an alternative amine type, so that the flow rate of the water is increased and the flow-through exchange capacity is reduced. The frequency of reproduction can be extremely low, and advantageous operation can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram showing an embodiment of a condensate desalination apparatus used in the method of the present invention.

FIG. 2 is a schematic system diagram showing another embodiment of a condensate desalination apparatus used in the method of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a flow rate of water and ion exchange performance.

FIG. 4 is a characteristic diagram showing a relationship between a flow rate and a once-through exchange capacity.

FIG. 5 is a characteristic diagram showing a relationship between a flow rate of water and an organic SO ₄ leak amount.

FIG. 6 is a schematic vertical sectional view showing the occurrence of inconvenience when the flow rate of water in a conventional desalination tower is increased.

FIG. 7 is a schematic longitudinal sectional view showing the occurrence of inconvenience when increasing the flow rate of water in another conventional desalination tower.

[Explanation of symbols]

 1,21 condensate desalination device 2,22 condensate system 3,23 filter 4,24 condensate filtration device 5,25 desalination tower 6,26 inlet pipe 7,27 inlet 8 baffle plate 9a as dispersing means, 9b, 29a, 29b End plate part 10, 30 Straight body part 11, 31 Perforated plate as rectification means 12 Screen 13, 32 Ion exchange resin 14, 33 Designed resin surface 15, 35 Outlet pipe 16 Resin transfer pipe 28 As dispersion means Distributor 34 Collector

Claims (4)

[Claims] 1. The desalination tower has a flow rate exceeding 150 m / h and 220 m / h.
A method for operating a condensate desalination apparatus, characterized in that water is passed at a linear flow rate of h or less. 2. A desalination tower provided with a dispersing means immediately after the inlet and a rectifying means on the downstream side in the water flow direction, and water is passed through the desalting tower at a linear flow rate of 130 to 220 m / h. A method for operating a condensate desalination apparatus, comprising: 3. The desalination tower has a flow rate exceeding 150 m / h and 220 m / h.
The method for operating a condensate desalination apparatus according to claim 2, wherein water is passed at a linear flow rate of not more than h. 4. The method for operating a condensate desalination apparatus according to claim 1, wherein operation of an ammonia type or an alternative amine type is performed.